Cellular Senescence Mechanisms Independent of Telomere Shortening and Telomerase: Other Barriers to Cell Immortalization and Carcinogenesis

Interestingness: 4

By Izumi Horikawa, Toshio Yawata, and J Carl Barrett in the Journal of Anti-Aging Medicine, Volume 3, Issue 4, 2000 (pp 373-382, doi:10.1089/rej.1.2000.3.373.)

 Not all cells given telomerase escape senescence and cells with active telomerase can be made to senesce in lots of ways. The p16^INK4A/RB pathway can trigger senescence as well as the p14^ARF/MDM2/p53 pathway. p53 is probably related to telomeres but other parts probably aren't. By introducing single chromosomes into immortal cancer cell-lines and making them senesce, they infer the existence of other independent pathways of senescence. The mechanisms that trigger senescence are cell-type dependent.

Interesting factoid: mouse cells senesce after much fewer replications (10-20 vs 50-80) even though much longer telomeres.

Telomeres, Telomerase, and Premature Aging

Interestingness: 4

By Corrin V Wallis and Richard GA Faragher in the Journal of Anti-Aging Medicine, Volume 3, Issue 4, 2000.

Nice summary of telomeres, telomerase and also about the relations of telomeres, Werner's syndrome, Hutchinson-Gilford progeria syndrome and aging. Quite a few details of the proteins involved that I wasn't aware of and that I'll forget about in the next hour.

Review of the Gerontology Literature in Volume 3, Issue 3

To be clear, this is the summary of the reviews, not the reviews themselves. Reviews by Barry Flanary

Subsenescent telomere lengths in fibroblasts immortalized by limiting amounts of telomerase, by Ouellette MM, Liao M, Herbert BS, Johnson M, Holt SE, Liss HS, Shay JW, Wright WE, in Biol Chem 2000;275:10072-10076

I don't think I understand this result. They transfected cells in-vitro with telomerase reverse transcriptase. Those cells had decreasing telomerase activity as they got older, and then lived longer (their number of doublings went from 60-70 to 250-400). Their telomeres shortened from the 1.5kb-10kb range to the 1.5kb-6kb range. Some theorising that the telomerase was preferentially taken up by the shorter telomeres, thus keeping it from hitting the criticial length at which the cells would go senescent.


Cytotoxic T cell immunity against telomerase reverse transcriptase in humans, by Minev B, Hipp J, Firat H, Schmidt JD, Langlade-Demoyen P, Zanetti M, in Proc Nati Acad Sci USA 2000;97:4796-4801.

Experimenting with using the immune system that naturally attacks hTERT to hammer tumor cells, since they produce hTERT. T cells from prostate cancer patient hammered some tumour lines.


Extension of cell life-span and telomere length in animals cloned from senescent somatic cells, by Lanza RP, Cibelli JB, Blackwell C, Cristofalo VJ, Francis MK, Baerlocher GM, Mak J, Schertzer M, Chavez EA, Sawyer N, Lansdorp PM, West MD, in Science 2000;288:665-669.


Cloning of cows from a 45 day old fetus. Resulting cells extracted from fibroblasts had higher replicative capacity and telomere lengths than controls. I'm sure we know much more about cloning now, so this has probably been overturned and back a hundred times.

Glucagon-Like Peptide 1 (GLP-1) in Diabetes and Aging

By David D'Alessio in the Journal of Anti-Aging Medicine, Volume 3, Issue 3, 2000.

Interestingness: 2

I'd never heard of GLP-1, but it seems to accentuate the glucose-lowering effect of insulin, by including but maybe not limiting to, increasing insulin secretion. Maybe also acts as a satiety marker. GLP-1 is synthesised in the intestines. Glucose eaten has much higher effect on increasing insulin than glucose injected.  Lots of problems in studies caused by mixing detection of active and inactive form of the peptide.

Giving up and Adrenal Andropause and Aging

Writing even the half-arsed summaries takes too long, so I'm giving up on those.  From now on, it will be most likely down to an interestingness score, tags and a one line summary, mainly for me to keep track of them.  Also, no more abstract cut-n-pasting, since it probably is not as legit as I thought it was before.


So, Adrenal Andropause and Aging, by Samuel SC Yen,  in the Journal of Anti-Aging Medicine, Volume 3, Issue 3, 2000.

Interestingness: 2

Nice review on cortisol changes with aging and DHEA/DHEA-S changes with aging, and how they diverge, cortisol going up and DHEA-S going down, post adrenopause (30s), even though they are both produced by the adrenal glands. Mentions possible link to immune system (DHEA-S inversely correlated to IL-6)

Predictors of Growth Hormone Secretion in Aging

Summary: Growth hormone again

Interestingness: 2

Paper by Mark L Hartman, Jody L Clasey, Arthur Weltman and Michael O Thorner in the Journal of Anti-Aging Medicine, Volume 3, Issue 3, Spring 2000.


(((
Growth hormone (GH) secretion goes down with age at an inversely logarithmic rate. It is almost down all the way by time we are in our 30s. This may not be due to age alone though, since there are high correlations between integrated GH concentration and each of BMI, percentage body fat and fitness, as measured by oxygen consumption, especially in men (in women the effect does not reach the magic 0.05).

Most of the reasons listed for the decrease we've seen before already (growth hormone papers). Some that I haven't:

• GH secretions four times higher during stage 3 and 4 sleep. Deep sleep goes to the shit with age.
• Possible path by which high fat reduces GH: high free insulin-like growth factor 1 (IGF-1). But then they quote study showing inverse correlation between free IGF-1 and visceral fat.

In their own studies, they find correlations between integrated GH concentration and each of abdominal visceral fat, fasting insulin and IGF-1, independent of age, sex, total body fat mass, percentage fat, 24 hour mean estradiol and testosterone, and peak oxygen uptake, in a group of 40 people in their 20s and 62 in the 57-80 year old range. Also, a high correlation between the combination of age and sex with IGF-1.

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Abstract follows:

Growth hormone (GH) secretion decreases progressively after mid-puberty in both men and women. This decrease occurs predominantly before age 40-50 and affects both daytime and nocturnal GH secretion. A reduction in the amplitude of GH secretory pulses accounts for the majority of the reduction in GH secretion. With aging, changes in hypothalamic function may occur that result in decreased GH secretion. These changes may include decreased secretion of GH-releasing hormone and/or the putative natural ligand for the GH secretagogue receptor or an increase in somatostatin release. Multiple physiological factors have been reported to regulate GH secretion including sleep, body composition (% body fat and amount of abdominal visceral fat), aerobic physical fitness and serum concentrations of insulin-like growth factor-I (IGF-I), gonadal steroids and insulin. Changes in these factors with aging may contribute to the reduction in GH secretion observed in older adults. However, these physiological predictors of GH secretion are not independent of one another and the relative importance of these factors in the regulation of GH secretion is not known. Preliminary evidence suggests that the amount of abdominal visceral fat and fasting serum concentrations of insulin and IGF-I are the most important predictors of 24-hour GH release in healthy adults, independent of age and gender. Bi-directional feedback between these three factors and GH secretion may account for the strong relationships observed.

Network-Like Facets of Neuroendocrine Aging in the Human: Specific Disruption of Feedback and Feedforward Linkages Within the Aging Somatotropic ...

Full title, since it didn't fit: Network-Like Facets of Neuroendocrine Aging in the Human: Specific Disruption of Feedback and Feedforward Linkages Within the Aging Somatotropic, Gonadotropic, and Corticotropic Axes in Men and Women

Summary: Lots of facts about growth hormone, leutinising hormone, follicle-stimulating hormone and gonadotropin-releasing hormone, with very little cohesion.

Interestingness: 3

Paper by Johannes D Veldhuis in the Journal of Anti-Aging Medicine, Volume 3, Issue 3, Spring 2000.


(((
This is another long review paper by Veldhuis mainly about growth hormone (GH) and its friends, even though its supposedly about the interaction between different hormonal axes. It has 266 references. It's too much information to summarise. I'll jot some notes. A lot of the same information as in Veldhuis's previous paper is covered as well as in all the other GH papers. I'll skip bits that I think are repeated. A lot of the graphs presented don't look very convincing. They tend to have around 10 people per group, so the curves look like they could change easily.

Newer data says more GH secreted by women than men, and decline with aging is half as slow.
Secretion pulses more irregular and lower in older people for GH, leutinising hormone (LH), insulin and prolactin. Follicle-stimulating hormone (FSH) secretion pulse and base go up.
Intra-venous gonadotropin releasing hormone (GnRH) pulses normalised LH secretion in older men.

Inferenced mechanisms mentioned:

• Lower endogenous growth hormone-releasing hormone (GHRH) secretion and/or lower growth hormone releasing peptide (GHRP) effect could explain loss of GH secretory pulse.
• Evidence for too much somatostatin and GHRH deficiency. Neither alone enough.
• Partial GnRH deficiency and Leydig-cell steroidogenic defect both exist, and the latter is not fixed by external GnRH.

They do some computer models of the GnRH-LH-T axis and from those they like the following hypotheses for the loss of synchrony between LH and T release in older men:

• Lower feed-forward drive of T synthesis by Leydig cells.
• Same, plus lowered negative-feedback by T of GnRH and LH release.

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Abstract follows:

The present update highlights the impact of age on dynamic regulatory changes arising singly and multiply within several prototypical neuroendocrine axes in the human. A neuroendocrine axis is viewed here as a homeostatic unit maintained by multivalent interactions or network-like integration among CNS-hypothalamic, pituitary, and target-tissue sites; for example, the GHRH/somatostatin-GH-IGF-I, GnRH-LH-sex-steroid and CRH/AVP-ACTH-cortisol feedback-controlled axes. Homeostatic control is driven by (time-lagged) interglandular signaling and dose-sensitive interfaces. According to this broader perspective, a neuroendocrine system operates as an interdependent ensemble of reciprocally communicating control nodes. This dynamic precept provides a foundation for identifying among the earliest vivid features of signaling disruption within the somatotropic, gonadotropic, and corticotropic (as well as insulinotropic) axes in healthy aging men and women. Internodal linkages likely deteriorate further in the face of acute or chronic illness, medication use, systemic stress and/or hospitalization, resulting at times in overt failure of neuroglandular output. This extended concept offers a notion of neuroendocrine axis frailty as a precursor to frank endocrinesystem disability in aging. Such a framework also confers the expectation that pluri- or multiaxis disruption (e.g., combined somatotropic and gonadal) would further adversely impact homeostatic vigor in aging individuals.

About-Daily (Circadian) and About-Weekly (Circaseptan) Patterns of Human Salivary Melatonin

Summary: Chronobiology weekly.

Interestingness: 1

Paper by Manfred Herold, Germaine Cornélissen, Mary Jo Rawson, George S. Katinas, Cheryl Alinder, Chris Bratteli, Denis Gubin, Franz Halberg in the Journal of Anti-Aging Medicine, Volume 3, Issue 3, Spring 2000.


(((
They analysed the melatonin and cortisol content of the saliva of five people 29-73 years of age for a week. They think there's a weekly cycle in melatonin, peaking on Tuesday. I'm close-minded.
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Abstract follows:

Circadian rhythms in circulating, urinary, salivary, pineal, pituitary and hypothalamic melatonin have been mapped. About weekly (circaseptan) rhythms, mapped previously in several other species, are demonstrated herein for human saliva, in individuals of widely differing ages. Whether or not the now demonstrated decrease with age in the circadian amplitude of human adults is accompanied by an increase in the circaseptan amplitude, as it is the case for blood pressure, remains to be determined.

Serum Schiff Bases Are Elevated in Patients with Dementia

Summary: Schiff bases are more prevalent in demented people's blood, whatever that means. Lipid peroxide levels are lower, whatever that means as well.

Interestingness: 2

Paper by Aleksandra Musial, Tadeusz Pietras And Dariusz Nowak in the Journal of Anti-Aging Medicine, Volume 3, Issue 3, Spring 2000.


(((
Straight forwards report of testing of four oxidation markers in the blood of 30 old people with clear dementia compared against 18 old people without clear dementia. Conjugated dienes (CnH(2n-2) for values of n, wikipedia tells me) were at about the same concentration in both groups; TBARS (ThioBarbituric Acid Reactive Substances, formed by lipid peroxidation, again, thanks wikipedia) were about 20% higher in demented, but not significant to the 0.05 standard; lipid peroxides were three and a half times higher in the non-demented, and Schiff bases were about 80% higher in the demented.

They are obviously trying to claim higher oxidation levels in the demented. Schiff bases fits their model (I didn't look into how they form). The lower lipid peroxides doesn't, so they come up with reasons. They also find lower lipid peroxides with age in the non-demented group. One possible excuse: lower amounts of poly-unsaturated fatty acids in the brains of older people, supposedly found by someone else.

Anyway, not very interesting, but bonus points for the cool abstract.
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Abstract follows:

Hypothesis

Increased oxidative stress may accompany diseases of the central nervous system either as a perpetrator or merely as the result of tissue damage in the course of neurodegeneration. The brain is especially susceptible to damage mediated by reactive oxygen species because it has a high rate of oxygen consumption and contains large amounts of readily oxidizable substrates, such as polyunsaturated fatty acids. Indices of systemic oxidative stress, including serum lipid-peroxidation products, may be greater in dementia than in normal aging.


Methods

Study groups consisted of 30 patients with dementia and 18 healthy age-matched controls. All patients underwent neuropsychological testing and qualified for the study on the basis of history, physical examination, complementary laboratory tests, and brain computed tomography scan. Serum levels were assessed for the following lipid-peroxidation products: conjugated dienes, lipid peroxides, thiobarbituric acid reactive substances, and Schiff bases.


Results

There were two statistically significant differences in serum levels of lipid-peroxidation products between the study groups. Lipid peroxides were significantly lower (0.34 Å 0.09 U532/mL versus 1.12 Å 0.96 U532/mL, p = 0.000055), while Schiff bases were statistically higher (589.4 Å 267.3 AU/mL versus 329.0 Å 107.5 AU/mL, p = 0.000282) in the subjects with dementia. There were statistically significant correlations between all measured products of lipid peroxidation in the controls and between all products of lipid peroxidation except for Schiff bases in the subjects with dementia. Cognitive impairment did not correlate with levels of lipid-peroxidation products. Age correlated negatively with Mini-Mental State Examination score and lipid peroxides in healthy controls.


Conclusion

More final fluorescent products of lipid peroxidation (Schiff bases) were found in subjects with dementia than in healthy controls, implying that oxidative stress is increased in dementia. Our data suggests a decrease in lipid peroxides during normal aging.

Serum Thiols as a Surrogate Estimate of DNA Repair Correlates to Mammalian Life Span

Summary: Mammalian species with higher thiol fractions in their protein live longer

Interestingness: 2

Paper by Ronald W Pero, Catharina Hoppe and Yezhou Sheng in the Journal of Anti-Aging Medicine, Volume 3, Issue 3, Spring 2000.


(((
These people grabbed blood samples from mostly one or two specimens of 17 different mammalian species (mouse, rat, wolf, dog, goat, sheep, rabbit, bear, cat, lynx, musk ox, fallow deer, cow, gorilla, chimpanzee, horse and human) and precipitated the proteins in those samples. They found a correlation (r=0.819) between the proportion of thiol in the precipitate and the lifespan of the species (not the specimen, they didn't measure how long the actual specimen they took blood from lived), and a stronger correlation (r=0.841) between the proportion of thiols in the thiol-rich fraction of the proteins and the lifespan of the species.

The plots don't look as good as the r-numbers would indicate because they are heavily influenced by the human specimens since they were many more of them (25 vs 1 or 2 of each of the others), and they are out there way on the right in the lifespan axis (they were assigned a lifespan of 95 years). The graphs don't look horrible either.

Their theoretical explanation confuses me. They are saying that this shows that creatures with higher lifespan have lower oxidation levels. I don't know if they are saying that this is being shown directly, that is oxidation would get rid of the thiol (this assumes that their measuring of the thiols wouldn't count oxidised thiols in them), or that this is being shown indirectly, that is if high lifespan animals didn't have lower oxidisation levels their higher thiol-fractioned proteins would be more affected by oxidation, their enzymes would not work, and so these animals wouldn't have high lifespans. I think they mean the second explanation, but I'm not sure. Backing this second interpretation, is them pointing at the unoxidised thiol-dependence of poly adenosine diphosphate-ribose polymerase (PARP), a DNA-repair enzyme, and from there making other claims about the link between mutation, DNA repair and oxidative stress.
)))


Abstract follows:

Biologically occurring thiols are a sensitive estimate of the reduction/oxidation balance of cells, being easily and reversibly converted from sulfhydryl to disulfide structures in proteins and amino acids. Thiols are also known to regulate DNA repair, especially via the influence on poly (adenosine diphosphate-ribose) polymerase activity. Here the thiol content of saturated ammonium sulphate-precipitated proteins from sera was correlated to a mammalian life span of 17 species. A close correlation was established between the thiol-rich proteins and the life span of the mammals (r = 0.841, p < 0.001). These data provide a strong scientific connection between mechanisms of DNA repair and oxidative stress leading to DNA damage accumulation and mutation, which may be important to the aging process.

Rest of volume 3, Issue 2

The rest of issue 2 of 2000 consists of:

A summary of the Templeton conference "Extended Life - Eternal Life" by Michael Fossel. About ethics.

A review of the book "Time of Our Lives: The Science of Human Aging". Book by Tom Kirkwood, review by Robert Arking. Positive review, popular access book.

A review of a paper by Junji Yodoi and Lester Packer, "Redox Regulation in Eukaryotic Cells Based on Thio-Redoxin Enzymes". Interesting bit about mice with upregulated thioredoxyn ("against UV in the bone marrow" it says, no idea what that means in this context) gene having an increased lifespan.

Endocrinology of Benign and Malignant Prostate Disease in Aging

Summary: Prostate cancers are out to get us, and too many hypothesis on why they grow.

Interestingness: 3

Paper by Marco Marcelli, TC Shao and Glenn R Cunningham in the Journal of Anti-Aging Medicine, Volume 3, Issue 2, June 2000.

(((
This paper is about the relationship between androgens, testosterone (T) and dihydrotestosterone(DHT), and estrogens, and prostate cancer (CaP in the text for some reason, but I'll go with the more obvious PC) and benign prostate hyperplasia (BPH), but the bits that interested me were the general stats and information about PC and BPH. It is also one of those that is a summary itself so there's too much information and I end up paying attention to none of it.

Check these numbers out, mostly related to USA population, male only:

• 28.7% of new, nonskin cancers
• 12.7% of cancer-related deaths
• BPH in 10% of 35 year olds, >80% of 80 year olds.

Latent PCs found in

• 15-20% of 40-50 year olds (found in autopsies, deaths from other reasons)
• >50% of 60-70 year olds.

The latent PC numbers seem especially scary for me. They seem to indicate that if we do extend lifespan, these will become active problems, not just latent.

The study focuses quite a bit on cross-ethnic variation of PC and BPH rates, and correlations or lack thereof with androgen levels. It then runs through the non-exclusive hypothesis for the cause/s of BPH and PC. For BPH: increased androgen concentration, something about estrogen, dysregulation of growth factors, and an increased in the number of stem cells. For PC: mutation in SRD4A2, androgen receptor (AR) gene codon repeats, and insulin-like growth factor 1 (IGF-1). I didn't pay much attention to the details of the hyopthesis.

Treatment/preventions: 5alpha-reductase inhibitors (5alpha-reductase converts T to DHT), like finasteride, which supposedly work well in the prevention of BPH, but don't do much once BPH is severe (well, 20-30% reduction in volume). For PC, castration, I assume chemical, induces remission on 80% of PC patients, but it mostly lasts 12-18 months, after which the PC recovers and 70% of the patients die.

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Leptin Resistance with Age-Related Obesity

Summary: Explains the link between leptin, neuropeptide Y (NPY) and obesity in a rat model of age-related obesity they like

Interestingness: 1

Paper by Philip J Scarpace and Nihal Tümer in the Journal of Anti-Aging Medicine, Volume 3, Issue 2, June 2000.

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They found a type of rat, F-344xBn, that gains weight in a similar manner to humans, slowly building up until 60 years of age/24 months for human/rat, and then slowly going down.

In young rats, higher leptin led to lower NPY. "NPY stimulates feeding and decreases energy expenditure". Fasting lowers leptin levels. Leptin is produced by white adipose tissue (not sure if only there). In young rats, there's a nice inverse relation between NPY and leptin. The relation isn't clear in old rats, and the inhibition of NPY by leptin also becomes clear. They track the relation to some other proteins and brown adipose tissue, but I don't care enough so I'd probably misrepresent the content.

They think the same thing could be true in humans. I remember something about leptin acting differently in rats (or was it mice) and humans. Maybe not in these rats.
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Abstract follows:

Leptin, synthesized by white adipose tissue, interacts with the appetite and satiety centers to regulate body weight, and this hormone contributes to the regulation of both food intake and energy expenditure. Serum leptin is elevated in most obese humans, and that obesity persists in spite of the elevated leptin, suggesting leptin resistance. The F-344xBn rat strain, similar to humans, demonstrates a steady increase in body fat and serum leptin into early senescence. Thus, these aged rats become obese in spite of the elevated leptin, suggesting the relationship between leptin, adiposity, and food intake is altered with age. Leptin modulates a number of neuropeptides in the hypothalamus, including neuropeptide Y (NPY). NPY both stimulates feeding and suppresses thermogenesis in brown adipose tissue. Following leptin infusion, the decrease in food intake and the increase in energy expenditure were blunted in the aged rats. Moreover, leptin decreased NPY mRNA in young but not senescent rats, suggesting that leptin signal transduction may be impaired. Leptin receptor signal transduction involves phosphorylation of cytosolic signal transducer and activator of transcription (STAT) proteins, specifically phosphorylation of STAT3 (P-STAT3). Leptin-induced P-STAT3 levels were unchanged with age, but the dose of leptin required for half maximal stimulation was 5-fold greater in the older rats, suggesting that sensitivity for leptin signal transduction is diminished with age. In summary, aged rats demonstrate a reduced responsiveness to leptin, and the mechanism may involve impaired suppression of hypothalamic NPY mRNA that may be a consequence of impaired leptin signal transduction. This leptin resistance may be due to either the elevated obesity and serum leptin with age or due to age itself or both.

Contemporary Clinical Research on Menopause

Summary: More studies needed on menopause

Interestingness: 1

Paper by Robert W Rebar in the Journal of Anti-Aging Medicine, Volume 3, Issue 2, June 2000.

(((
I think this is meant to be a review paper but it doesn't have much content. The author wants some interventional studies done. There doesn't seem to be any reliable predictive markers of when menopause will happen. Hot flashes happen to 85% of women during the perimenopausal and early menopausal periods. Estrogen sometimes cures hot flashes. Author doesn't like studies that combine women without ovaries with ones that do, and the same about women with premature ovarian failure. That's it.
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Abstract follows:

To the present time, knowledge about menopause has accumulated largely because of observational and epidemiological studies in postmenopausal women. The challenge for the years ahead is to utilize the information learned from several large epidemiological studies, including the Postmenopausal Estrogen-Progestin Intervention (PEPI) trial, the Women's Health Initiative (WHI), and the Study of Women's Health across the Nation (SWAN), to develop testable hypotheses. Studies of pharmacological agents have also provided information that may be of use in this regard. Some women with so-called premature ovarian failure may form another appropriate experimental group. Appropriate questions for future study are abundant. Why do some women develop vasomotor instability, whereas others never complain of any associated symptoms? Can we predict which women will develop osteoporosis and which will not? Which changes occurring after menopause are related to the cessation of ovarian function and which changes are related to aging? Investigation of these and other such questions will require a return to clinical research that is not population based. This presentation will review some of the advances that have been made by clinical investigation and suggest approaches and questions for the years ahead.

Progress in Erectile Dysfunction and Hormone Function

Summary: If your dick don't work try Viagra

Interestingness: 1

Paper by Pejman Cohan and Stanley G Korenman in the Journal of Anti-Aging Medicine, Volume 3, Issue 2, June 2000.

(((
Lots of overlap between this paper and the previous two. It describes the mechanism of how an erection comes to be and all the stages at which it can stop working, the non-effectiveness of testosterone in solving the issue, even though it helps with libido (something that the previous paper had some doubts over), and then lists possible solutions with Viagra at the top of the list, supposedly working 50-70% of the time.

Some interesting random numbers from the rest:

• Testosterone drops 110 ng/dL every decade.
• 15% of people over 80 had normal levels of testosterone in a study of 300.
• In the Massachusetts Male Aging Study, which google tells me was on 1290 men, a quarter of the 40-70 year olds had a moderate degree of erectile dysfunction (ED). Not sure what a moderate amount is though

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Abstract follows:

The concept of "andropause" has recently gained popularity as increasing evidence suggests that aging in men is accompanied by a progressive decline in serum testosterone levels. The pathophysiologic mechanism responsible for this decline is not fully understood. However, perturbations at every level of the hypothalamic-pituitary-gonadal system have been demonstrated. Age is also a strong risk factor for erectile dysfunction (ED). Although it is tempting to conclude that a causal relationship exists between declining androgen levels and ED, our current understanding of the erectile process and the failure of testosterone supplementation to restore erectile function in older men suggest that these processes are independent. Furthermore, the recent availability of effective oral therapies for ED argues against the indiscriminate administration of androgens to elderly men with ED. However, the beneficial effects of testosterone on libido, mood, bone density, and body fat composition may justify its use on an individual patient basis.

Endocrine Determinants of Successful Aging in the Male

Summary: A whole bunch of hormone levels go down when men get old

Interestingness: 3

Paper by Annewieke W van den Beld and Steven WJ Lamberts in the Journal of Anti-Aging Medicine, Volume 3, Issue 2, June 2000.

(((
This is another paper that reads like a review paper, even though they keep referring to their study of 400 73-94 year old men in the Netherlands. Most of what's quoted is about other studies. When they talk about their own study, I'll note it, and I'll mainly focus on their results, not the survey. Their study mostly lacks graphs and numbers, so I'll stick to what they describe it as (increase, decrease, etc).

They "confirm" other studies that say that muscle strength is the major feature that determines whether an old man remains functionally independent.

Mean serum total testosterone (T) in males goes down by about 30% between being 25 and 75. Mean serum free T goes down by 50%. The difference is explained by an increase in sex-hormone-binding globulin (SHBG). In their study they found a correlation between free T and muscle strength, but none between T and life satisfaction.

In their study they see luteinising hormone (LH), which triggers release of T by the testicles, going up with age, and it being inversely correlated with T concentrations. Other studies show mixed results for this relation.

Drop in estradiol (E2) and estrone (E1) with age. In their study, strong correlation between E2 and bone density, and E2 and life satisfaction.

Drop in dehydroepiandrosterone (DHEA) and DHEA sulphate (DHEAS) with age. DHEAS level at 85 is one fifth of level at 30. DHEAS levels in adults > 10 times higher than cortisol (!). In their study, no relation between DHEAS and muscle strength, and relation between DHEAS and bone density disappears when adjusting for T and E1,E2 levels.

And again growth hormone (GH) secretion drops with age, insulin-like growth factor 1 (IGF-1) drops with age, IGF-binding protein 3 (IGFBP-3) drops with age, but IGFBP-2 and IGFBP-1 increase with age. Their study concurs. Also in their study, they didn't see relation between IGF-1 and physical functional status, but did see a strong inverse relation between IGFBP-2 and muscle strength, and they like IGFBP-2 as an indicator of overall level of physical functional status.
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Abstract follows:

Frailty is characterized by generalized weakness, impaired mobility and balance, and poor endurance. Loss of muscle strength is an important factor in the process of frailty, and is the limiting factor for an individual's chances of living an independent life until death. In men, several hormonal systems show a decline in activity during aging. Serum bioavailable testosterone (T) and estradiol (E2), dehydroepiandrosterone (DHEA) and its sulphate (DHEAS), and growth hormone (GH) and insulin-like growth factor (IGF)-I concentrations all decrease during aging in men. Physical changes during aging have been considered physiological, but there is evidence that some of these changes are related to this decline in hormonal activity. Studies on hormone administration in the elderly appear to be promising. However, until now, hormone replacement is not yet proven to beneficial and safe.

GH Secretagogues in Aging

Summary: Growth hormone secretagogues bind all over the place. Not much to recommend them.

Interestingness: 2

Paper by Emanuela Arvat, Roberta Giordano, Fabio Broglio, Laura Gianotti, Lidia Di Vito, Gianni Bisi, Andrea Graziani, Mauro Papotti, Giampiero Muccioli, Romano Deghenghi and Ezio Ghigo in the Journal of Anti-Aging Medicine, Volume 3, Issue 2, June 2000.

(((
This covers similar ground to the other papers on growth hormone that I've summarised before (http://readingrejuvenationresearch.blogspot.com/search/label/growth hormone) but talks only about the synthetic compounds. I think all the studies it mentions are very small (around 20-30 people). This is an eighth-assed attempt at a summary.

The GHS are treated as a group but it seems like there's a lot of differences between them which I won't summarise. The method of inducing growth hormone (GH) release seems to be as a somatostatin (SS) antagonist. The GH stimulation effect is high in puberty and adults, but not on old people. Hypothalamic receptors were lower in middle aged and old people, than in young adults.

Some studies show increase in GH, insulin-like growth factors (IGF) I and II, and IGF binding protein 3 (IGFBP3) in old people when given specific GHSes, others increase in fat-free mass and energy expenditure in obese people, others no change in fat or lean mass in elderly. All of these are shortish (2-month), small studies.

Also reported on non-GH effects of GHS, like release of prolactin (PRL) and adrenocorticotropic hormone (ACTH), and bindings all over the cardiovascular system, with maybe some anti-apoptotic effect.

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Abstract follows:

Growth hormone (GH) secretagogues (GHS) are synthetic peptidyl and nonpeptidyl molecules which possess strong, dose-dependent and reproducible GH-releasing activity, even after oral administration. GHS release GH via actions on specific receptors at the pituitary and, mainly, at the hypothalamic level. GHS likely act as functional SS antagonists and meantime enhance the activity of growth hormone-releasing hormone (GHRH)-secreting neurons. In fact, GHS need the integrity of hypothalamus-pituitary unit to fully show their GH-releasing effect. The GH-releasing effect of GHS is reduced in aging likely reflecting concomitant GHRH hypoactivity and somatostatinergic hyperactivity, though impaired activity of the putative GHS-like ligand and/or receptors has also to be taken into account. Orally active GHS have been proposed as rejuvenating anabolic treatment of somatopause (age-related changes in metabolism, structure functions, and body composition partially reflecting the aging of GH/IGF-I axis). No definitive evidence of their clinical usefulness as anabolic agents has been provided yet. On the other hand, GHS have specific receptors in other central and peripheral endocrine and nonendocrine tissues. These receptor subtypes mediate GH-independent biological activities linked to the neuro-endocrinology of aging. For instance, GHS: (a) possess adrenocorticotropic hormone (ACTH)-releasing activity, which is increased in elderly subjects; (b) influence sleep pattern rejuvenating it in elderly subjects; (c) stimulate food intake; (d) have cardiovascular activities including protection against cardiac ischemia and cardiomyocyte apoptosis as well as increase in cardiac contractility. These "other than GH" central and peripheral activities are now carefully under evaluation.

Rest of volume 3, Issue 1

The rest of issue 1 of 2000 consists of:

• A summary of the 52nd Annual Meeting of the Gerontological Society of America, by ADNJ de Grey. Highlighted results: Extension of fruit fly maximum lifespan by overexpression of mitochondrial superoxide dismutase. Extension of maximum lifespan in nematode by supplementation of something that has superoxide dismutase and catalase activity.
• A summary of the Oxygen Society/Free Radical Research Society Annual Meeting, by GR Buettner and FQ Schafer, which seemed to be a mixture of lectures and conference. Talks about the importance of nitric oxide in mitochondrial respiration, protein carbonyls as aging markers, various supplements, and iron(II)-dioxygen as main oxidisers.
• A four-part discussion about the paper by Kowald and Kirkwood (http://readingrejuvenationresearch.blogspot.com/2011/01/modeling-role-of-mitochondrial.html) from volume 2, issue 3, that extends de Grey's model on mutant mitochondrial amplification.
• • A letter by SR Primmer adding a selection effect to the demise of mutant mitochondria in replicating cells, by mutant mitochondria-containing cells committing apoptosis. On the other hand, it points out that aged rats have higher percentage of mitochondria with lower membrane potential. It mainly presents an alternative hypothesis to the survival of mutant mitochondria by suggesting that the mitochondrion takes an active role in destroying itself and that the mutant version probably survives by failing to perform the self-destruction. It also claims that telomere shortening will be important in-vivo quoting examples similar to the ones in the article in this issue (http://readingrejuvenationresearch.blogspot.com/2011/04/role-of-cell-senescence-in-human-aging.html)
  • A Kowald gives a short reply saying he can't see how mitochondria can be part of their own destruction given the genes they have, and that various different mutations are amplified (if most genes are needed for self-destruction, then most mutations would stop it from performing that action though)
  • de Grey gives a longer reply pointing out a difference in methodology of the study showing lower membrane potential in older cells making it irrelevant. He also tries to split the theorising of the mechanism of mitochondria destruction from the trigger/selection of which mitochondrion to destruct, (wouldn't keeping them joined lead to simpler theories?) and assigns Primmer's mitochondrial involvement in the self-destruction as part of the mechanism, not the trigger, thus being compatible with the other theory.
  • Fossel finaly editorialises about the topic. All four have different interpretations of the result that mice lacking telomerase are mostly fine until the sixth generation, and they mostly want results on the opposite case, ie when telomerase is turned on all the time on all cells.

Role of Cell Senescence in Human Aging

Summary: Cell senescence is the problem, but we won't talk about cancer.

Interestingness: 7

Paper by Michael Fossel in the Journal of Anti-Aging Medicine, Volume 3, Issue 1, Spring 2000.

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This paper is mostly a defense of the senescence model of aging which consists of saying that cell senescence is the main reason for aging. The paper consists of clarifications on possible misinterpretations of the theory. The model, it says, only pertains to human aging. It says that in critical tissue, enough cells senesce for it to have organism-wide effects, either by their inability to replicate, or by their changed gene expression patterns.

The clarifications are presented by examples. One main example is that heart attacks and strokes are compatible with the theory. Damage to the endothelial cells, the surface layer, cause neighbouring endothelial cells to replicate. At some point they senesce, at which point the holes on the surface aren't fixed any more and the plasma has direct access to the subendothelial layer, triggering the rest of the effects. A bit of supporting evidence is that the places on the blood vessels at which atherosclerosis is usually formed are the same places at which telomere length of endothelial cells is shortest.

The paper has doubts about the ability of the model to explain Alzheimer's but it suggests that since astrocytes divide, measuring telomere length in astrocytes and comparing to Alzheimer's propensity would be a good test.

There is an interventionist undertone to the paper, which is why I think it is interesting. It wants to shove human telomerase (hTERT) in tissue (leukocyte stem cells, the skin of Hutchinson Gilford Syndrome patients, arterial endothelial cells) and see if that fixes them or affects longevity. It mentions unpublished experiments, at least unpublished at that time, about using young cells vs old cells vs old cells with telomerase, in forming skin layers on a naked mouse. The old cells formed skin that looked like old human skin, while the young and telomerased cells formed normal, "grossly, microscopically and genetically", looking skin.

I am a bit surprised that the paper doesn't mention cancer at all. Senescence seems like a method of cancer control so I'd expect something to be said about it. The theory is vague and broad enough to be compatible with lots of other theories of aging, but I think it is not compatible with the mitochondrial free radical theory of aging. The one presented here seems easier to test.

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The notion that cell senescence might, ultimately, be central to human aging has been attractive but unsubstantiated for the past four decades. Recent genetics and cell biology work has strongly supported this position. The model has been criticized, largely because few understand what the model actually says about aging. The cell senescence model (often mislabeled the "telomere theory of aging") suggests that changes in gene expression within senescent cells underlie most common age-related pathology, for example those occurring in the coronary arteries in atherosclerosis. It does not suggest that most somatic cells senesce, but rather that those cells which do senesce (e.g., endothelial cells, chondrocytes, fibroblasts, keratinocytes, microglia, hepatocytes, etc) are common denominator of human aging and age-related disease as well as the most efficient point for therapeutic intervention. The cell senescence model of human aging remains elegant and consistent with all known data on human aging and disease; an appropriate criticism is that it remains yet unproven.

Chronobiology: Time Structures, Chronomes, Gauge Aging, Disease Risk Syndromes and the Cosmos

Summary: Waka waka waka wakke waka waka weh weh

Interestingness: 1

Paper by Franz Halberg, Germaine Cornéissen, Chen-Huan Chen, George S. Katinas, Kuniaki Otsuka, Yoshihiko Watanabe, Manfred Herold, Alexander Loeckinger, Alexander Kreze, Eva Kreze, Federico Perfetto, Roberto Tarquini, Cristina Maggioni, Robert B Sothern and Othild Schwartzkopff in the Journal of Anti-Aging Medicine, Volume 3, Issue 1, Spring 2000.

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This is a long sell-piece of the field of chronobiology. They want people to analyse data assuming a cyclic underlying pattern. I liked their last paper (http://readingrejuvenationresearch.blogspot.com/2010/06/circadian-hyper-amplitude-tension-chat.html), it was a bit out there, used quite unusual-to-me analysis and graphs, and had a bit of data. This one is waaaayyyyy too out there. They basically want to pump the study of all time cycles, and though I can see good reasons for circadian and yearly and all sorts of in-between rhythms being important, they suggested links between the sunspots on the sun and the levels of some type of steroids in urine based on the collections of one person for 1.5 cycles. I'm not buying this second type of cycle. I was surprised this paper was not rejected based on its literary style alone.
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For dealing with everyday physiology, that is, with respect to physiological variation in the normal range, the prevailing position corresponds to that in preatomic physics. The "a-tom" was then the smallest known particle that could not be further split. Breaking the atom opened the door to a new universe of particles governed by new forces and physical laws. Nuclear physics evolved and brought new knowledge, a new energy source and a wealth of practical applications. The analogy applies to the splitting of the normal range into the time structures of everyday physiology. From picking different times of day and seasons for study, a trans-disciplinary science, chronobiology, emerged. Chronobiology objectively maps chronomes (portmanteau'd from chronos = time and nomos = rule), time structures quantifying the relations among cycles and other events. The chronomes of variables in and around us intermodulate with each other; thus, we start exploring organisms as dynamic systems open to their environments near and far, and dependent upon them, beyond air and food. Entering the realm of everyday physiology allowed us to quantify, with refined indices, associations of life with remote drummers. The intermodulating feedsideward mechanisms involved in cosmophysical associations of life on earth may be in part endocrine responses to factors far beyond visible light and temperature. Pertinent knowledge may serve to optimize the quality and duration of life.

Imidazole-Containing Peptidomimetic NACA as a Potent Drug for the Medicinal Treatment of Age-Related Cataract in Humans

Summary: N-alpha-acetylcarnosine probably does good things for cataract patients

Interestingness: 2

Paper by Mark A Babizhayev, Valentina N Yermakova, Anatoly I Deyev and Marie-Christine Seguin. in the Journal of Anti-Aging Medicine, Volume 3, Issue 1, Spring 2000.

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Smallish trial on 49 humans, seeing if N-alpha-acetylcarnosine (NACA) does something for the eyes of cataract patients that are not in bad enough conditiones to go to surgery for it. It seems to do things, good things.

The theory is that the NACA gets converted to L-carnosine in vivo, and this acts as an anti-oxidant preventing or reversing cataracts. Not much more is given, but inhibition of phosphatidylcholine liposomal peroxidation is mentioned. Phosphatidylcholine is a major component of the cell membrane.

They give the NACA in drops to the eyes for two years. All the improvement is seen in the first six months, and after that the levels are maintained. Control subjects deteriorate quite a lot in the period.

This paper has a very long methodology section that probably means something to ophtamologists and optometrists. It also has a lot of decent graphs in the results section.
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The objective of this manuscript is to test the efficacy of Nalpha-acetylcarnosine for the treatment of senile cataract in humans. It was designed as a randomized controlled trial. Forty-nine subjects-volunteers (76 eyes) with an average age of 65.3 ± 7.0 years were enrolled and randomized into two groups at diagnosis of senile cataract. Changes in lens clarity were measured and quantitated over 6 to 24 months thereafter. Patients administered 1% Nalpha-acetylcarnosine (NACA) (26 patients, 41 eyes = Group II), placebo composition (13 patients, 21 eyes) topically (two drops, twice daily) to the conjunctival sac, or were untreated (10 patients, 14 eyes); two latter groups of patients were combined into the control (reference) group I. Patients were evaluated upon entry, at every 2-month (Trial 1) and 6-month (Trial 2) intervals for best corrected visual acuity (b/c VA), by ophthalmoscopy, original techniques of glare test (Trial 1), stereocinematographic slit-image and retro-illumination photography with subsequent interactive digital image analysis and 3D computer graphics of the lens light scattering/absorbing centers. The intra-reader reproducibility of measuring techniques for cataractous changes was good with the overall average of correlation coefficients for image analytical data 0.830 and glare test readings 0.998. Group I of patients demonstrated the variability in densitometric readings of lens cloudings, negative advance in glare sensitivity over 6 months, and gradual deterioration of VA and gross transmissivity of lenses over 24 months comparatively to baseline and the 6-month follow-up examinations. As compared with baseline examination, over 6 months 41.5% of the eyes treated with NACA presented a significant improvement of the gross transmissivity degree of lenses, 90.0% of the eyes showed a gradual improvement in VA to 7-100% and 88.9% of the eyes ranged a 27-100% improvement in glare sensitivity. Topographic study demonstrated less density and corresponding areas of opacification in posterior subcapsular and cortical morphological regions of the lens consistent with VA up to 0.3. The total study period over 24 months revealed that the beneficial effect of NACA is sustainable. No cases resulted in a worsening of VA and image analytical readings of lenses in the NACA-treated group of patients. In most of the patients drug tolerance was good. Statistical analysis revealed the significant differences over 6 and 24 months in cumulative positive changes of overall characteristics of cataracts in the NACA-treated group II from the control group I. The N-acetylated imidazole-containing peptidomimetic NACA is proposed as an effective and physiologically acceptable drug for nonsurgical treatment of age-related and senile cataracts.

Neutrophil Phagocytic Function and Humoral Immune Response with Reference to Ascorbate Supplementation in Aging Humans

Summary: Vitamin C supplementations makes some immune system numbers in old people resemble the ones in young people

Interestingness: 3

Paper by Muthuvel Jayachandran, Packiasamy Juliet Arockia Rani, Palaniyappan Arivazhagan and Chinnakkannu Panneerselvam in the Journal of Anti-Aging Medicine, Volume 3, Issue 1, Spring 2000.

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The methodology description is a little bit confusing, but I think they grabbed 125 20-to-30 year olds and 132 >60 year olds, measured some immune system function numbers: neutrophil phagocytic index (guessing, how easily they eat things), neutrophil avidity index (guessing again, some kind of bonding strength measurement), nitroblue tetrazolium (NBT) reduction (some kind of neutrophil phagocytic potency measurement it says), leucocyte ascorbic acid (how much ascorbic acid in the white blood cells, supposedly a good thing), immunoglobin G, M and A, complement C3 (some protein complex that punches holes in bacteria) and soluble immune complex (SIC) index (nfi).

Old people's numbers were 0.001-significantly lower for the avidity index, the NBT reduction, the leucocyte ascorbic acid, the IgG, IgM, the C3 and SIC index. Taking vitamin C for 30, 60, or 90 days didn't change the youngun's numbers, but the oldies got all those numbers within the non-0.001-significant level off the young, mostly within one standard deviation, and crossed the 0.001 level from their previous measurement.

Sounds good. Reasons not to get excited: we know vitamin C does nothing good for lifespan in humans.

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Abstract follows:

Age-associated deficiency of vitamin C contributes to the impaired humoral immune response, which in turn plays a role in the increased risk of illness in old age. Healthy volunteers were given vitamin C supplementation. Neutrophil phagocytic function, complement C3 concentration, and immunoglobulin status were measured at 30, 60, and 90 days. Neutrophil phagocytic function and levels of serum IgG and IgM and leukocytic ascorbate were considerably lower in the aged humans, but these decreases were attenuated by vitamin C supplementation. The level of IgA was not affected by aging. Improved neutrophil phagocytic function and humoral immune response were associated with increased vitamin C status in the aged population and might well contribute to the decreased risk of disease in the aged.

Noncorrelation Between Maximum Life Span and Antioxidant Enzyme Levels Among Homeotherms: Implications for Retarding Human Aging

Summary: de Grey thinks that we need superoxide dismutase in our mitochondrial intermembrane spaces

Interestingness: 6

Paper by Aubrey DNJ de Grey in the Journal of Anti-Aging Medicine, Volume 3, Issue 1, Spring 2000.

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This is another theory/speculation paper by de Grey. He's trying to explain why there is no correlation between life span and antioxydant enzyme levels in warm blooded animals. His explanation sticks to the oxidative damage is bad, m'kay, trend and tries to fit the model to the data.

He partitions the rate of damage created by oxidation into four:

• Specific metabolic rate (SMR): rate of consumption of oxygen per gram of body.
• Leakiness: Proportion of oxygen that becomes superoxide.
• Superoxide potency (SP): Proportion of superoxide converted into other oxide radicals (eg hydrogen peroxide) instead of being pacified by antioxidant enzymes.
• Oxidisability of the tissue (OT): How easily the relevant tissue gets oxidised.

He notes that under this scheme, levels of antioxidant vitamins affect the OT and not the SP, since they act mainly to stop the chain of oxidation. SP is the rate factor that is not correlated with lifespan that is being explained in this paper.

SMR in warm blooded animals (homeotherms) is mostly determined by body size, and lifespan does correlate with body size. Lifespan depends not only on size though but seems to be well correlated with lifespan restrictions imposed by external causes. There isn't much evolutionary pressure to raise the aging-based lifespan of the animal if it is likely to die from other causes (eg getting eaten). Animals of similar weight but different chances of dying due to external causes have different lifespans (eg birds vs mammals).

In a study in primates, superoxide dismutase (SOD) did correlate with lifespan if the SOD levels were divided by the SMR when doing the calculation. Catalase, glutathione peroxidase (GP) and glutathione (G) didn't though. A less dodgy comparison, in that it didn't need the division by SMR factor, was one between rats and pigeons. Pigeons live about 8 times longer than rats even though they weight about the same. SOD levels in the pigeon were slightly higher, catalase much lower, and G and GP levels varied depending on the tissue. Another study showed similar results when looking at the canary (very low mass, very high lifespan), with not even SOD showing higher levels.

In the same studies, they showed a correlation between leakiness and rate of aging, and maybe one between OT and rate of aging. Lending support to this second correlation, de Grey mentions that fatty acids saturation in the membranes of the mitochondria and levels of non-enzymatic anti-oxidants (eg vitamins C and E) are higher in longer lived animals and these lower OT. This supposedly leaves SP as the only one out of the four factors that doesn't correlate in the predicted way with longevity.

de Grey's hypothesis to explain this is that there is no easy way for evolution to lower the SP because there are no SOD enzymes in the mitochondrial intermembrane space (MIMS) to mop up the superoxides. The selection for longer lifespan instead pushes the concentrations of non-enzymatic antioxidants (vitamins C and E) up all over the cell to get levels up in the MIMS, and the leakiness of the MIMS down which is the same mechanism that controls leakiness elsewhere in the chain. This then means that the concentrations of antioxidant enzymes in the non-MIMS regions become too high for the resulting lower radicals due to the improved leakiness and non-enzymatic antioxidant profiles, and these enzymatic antioxidant levels drift down to save resources until they match the levels that would lead to the same rate of damage as the other parts of the oxidation chain.

Since that paragraph contained the whole hypothesis I will write it again, but in expanded form. Homeotherms supposedly don't have any SODs in their MIMS but we do produce superoxides there (the evidence for that second part is probably not great). The damage caused by this, somehow (more on this later), limits our lifespan. For intelligent or otherwise flighty animals, where the external causes of dying are lower, there is a selective pressure, apparently, to raise our lifespan due to aging to match the lower external causes. Since it seems to be troublesome to introduce a SOD into our MIMS (and this supposed trouble to evolve a MIMS-SOD is the bit that to me seems weakest out of the chain of reasoning), homeotherms instead reduce the leakiness of the ATP-making mechanism, the leakiness factor, and raise the levels of non-enzymatic anti-oxidants, lowering the OT factor, to lower the total rate of aging. Now, lowering the leakiness of the process lowered the production of oxidants everywhere, not just in the MIMS, and raising the level of non-enzymatic anti-oxidants did the same everywhere, not just in the MIMS, so now, if we kept the same level of enzymatic anti-oxidants as before these last two improvements, the level of oxidants everywhere non-MIMS becomes too low for the available enzymatic anti-oxidants. By too low, he means that the bottleneck will be the MIMS oxidants, and everywhere else the oxidant damage will always be too low to matter. Since now the organism can get away with lowering the enzymatic oxidant levels in the non-MIMS sections, it does so, since it saves energy doing so.

That this non-correlation between enzymatic antioxidant levels and lifespan does not occur in flies and worms, (ie, in those species, the correlation does exist and is positive), means that the lifespan-limiting mechanism in flies and worms is different from homeotherms. de Grey suggests that this mechanism is the mutation of mitochondrial DNA (mtDNA) which tends to be attached to the inner surface of the inner membrane of the mitochondria. The mtDNA would somehow be damaged by the higher unquenched superoxide concentration across the inner membrane, in the MIMS. Old mammals have been shown to have high levels of mtDNA mutations, while this doesn't happen in flies and worms, maybe because they do not live long enough for the process of mtDNA amplification to take place. He's trying to tie it all back to his other paper (http://readingrejuvenationresearch.blogspot.com/2010/01/proposed-refinement-of-mitochondrial.html)

The suggested methods for testing the hypothesis: retarget MnSOD and CuZnSOD to the MIMS and check that they are useless there. If they are not useless, then it should have been easy to evolve those. Afterwards, retarget E Coli's iron-dependent SOD to the MIMS of mice, as has supposedly been done before in yeast, and see if that affects lifespan. That last check doesn't make sense to me. If the enzymatic anti-oxidants in the non-MIMS sections have drifted down until they are causing as much trouble as the MIMS oxidation, then lowering MIMS oxidation damage shouldn't affect the lifespan of the beasts. Doing this while raising enzymatic anti-oxidants throughout the cell might though.

In conclusion, another very interesting chain of causation hypothesis, but probably too long to have much of a chance of being correct.

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Abstract follows:

A series of studies over many years has conclusively disproved the hypothesis that longevity in warm-blooded animals (homeotherms) correlates with high levels of antioxidant enzymes: in fact, these variables generally exhibit a strong negative cross-species correlation. In flies and nematodes, however, substantial extension of maximum life span has resulted from genetic manipulations that increase antioxidant enzyme levels; these manipulations have always been associated with increased resistance to oxidative challenge, indicating that the life span extension is directly caused by the raised antioxidant capacity. This stark contrast merits careful analysis because it casts doubt on the value of short-lived invertebrates as models for the investigation of mammalian aging. Here is it shown that these results imply the existence, in homeotherms but not in flies or worms, of life span-limiting pathways of oxidative damage that are impervious to enzymatic antioxidants. This is shown to lend weight to the currently controversial theory that somatic mitochondrial DNA mutations contribute significantly to determining the rate of aging of homeotherms, and thereby suggests a feasible intervention to retard human aging.

Prevalence of Telomerase in Coronary Artery Atherosclerosis

Summary: Telomerase detected in atherosclerotic plaque tissue, likely to be related to restenosis.

Interestingness: 3

Paper by Madhu Gupta, Marie R Shogreen, Gregory A Braden, Wain L White and David C Sane in the Journal of Anti-Aging Medicine, Volume 3, Issue 1, Spring 2000.


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They measured the presence of telomerase in the bits cut out of 23 people that had directional coronary atherectomy (DCA). The bits cut out are blockages of the coronary artery and the DCA cuts it out. They correlated the tissues in which they detected telomerase with those that had restenosis, which is when the blockage/narrowing of the artery reappears.

They detected telomerase in 8 out of the 23 total, in 5 out of the 7 people who later developed restenosis, and on 2 out of the 10 who didn't (p < 0.05). Results were inconclusive for restenosis in the other 6. There was no correlation between what the people had come in for and the presence of telomerase.

They mention that atherosclerotic plaques have a monoclonal population of smooth muscle cells, but I don't know what other type you could have inside one person. They offer three explanations for the 35% detection rate of telomerase, that is, how come it's not 100%:

• that the tissue is maintaining its telomeres by means other than telomeres
• that the tissue is senescent or closer to senescence, with some evidence coming from studies on replicative capacity of muscle cells from plaque-derived tissue compared to healthy arteries. The presence of telomerase would probably be induced by cells having replicated beyond the normal senescent stage by a viral infection or broken tumor-suppressors, and that this would activate telomerase. These cells would then be better able to cause restenosis. I have no idea how much reality there is to that idea of telomerase reactivation.
• that there was no telomerase in the smooth-muscle cells at all, and instead the telomerase was detected from other cells in the tissue cut out. This could be from vascular stem cells, or from non-related cells like endothelial cells, lymphocytes or macrophages.

They also mention that the telomerase could be driving the hyperplasia not by replication but by stopping apoptosis.

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Abstract follows:

Telomerase is an essential enzyme for maintaining the telomeres of chromosomes and thereby enhancing the sustained replication of cells. Because atherosclerosis and restenosis are characterized by cellular proliferation, we determined whether telomerase enzyme activity was present in coronary artery tissue from 23 patients undergoing directional coronary atherectomy. Telomerase activity was determined from detergent lysates of the atherectomy tissue using an enzyme-linked immunoadsorbent assay (ELISA)-based modification of the Telomere Repeat Amplification Protocol. The presence of telomerase activity was correlated with the occurrence of coronary artery restenosis. Eight of the 23 samples (35%) were positive for telomerase. Seventeen of the 23 patients had adequate clinical follow-up to judge restenosis status. Of these, 7 had restenosis and 5 of these 7 had detectable telomerase. Of the 10 patients without restenosis, 8 were telomerase negative (p <= 0.05). We have shown, for the first time, that telomerase is found in 35% of atherosclerotic tissues. There was a strong trend toward an association between telomerase presence and restenosis in patients for whom follow-up data were available. The presence of telomerase in atherosclerotic tissue may enable a robust, sustained cellular proliferation in response to vascular injury that culminates in restenosis.

Rest of volume 2, Issue 4

The rest of issue 4 of 1999 consists of:

A review of a book called Essentials of Clinical Geriatrics, 4th edition, edited by Robert L Kane, Joseph G Ouslander and
Itamar B Abrass. "Concise" 621 pages of differences between geriatric and standard medicine.


Seven article reviews by L Stephen Coles:

• Gene expression profile of aging and its retardation by caloric restriction, by Cheoi-Koo Lee, Roger G Klopp, Richard Weindruch and Tomas A Prolla, in Science. Analysis of what genes change in muscle cells in old mice compared to young mice compared to old calorie restricted mice using a gene chip of 6000 genes. Lots of changes, with caloric restriction reducing the changes by 84%. L Stephen Coles thought this was a very important paper.
  
• Can human aging be postponed?, by Michael R Rose, in Scientific American. Some pop-sci sounding piece.
• Designer genomes, by Karen Hopkin, in Scientific American. Another pop-sci sounding piece about creating cells from scratch. Mentions Venter's knock out method of finding the minimal set. I didn't know he had been going at it that long.
• Telomeres and telomerase in cancer, by Christopher M Counter, in Science and Medicine. Supposedly nice graphics.
• Aging: The price of evolutionary success, by Robert F Rosenberger, in Science Spectra: The international magazine of contemporary scientific thought. About germ vs soma.
• The hunt for the youth pill: From cell-immortalizing drugs to cloned organs, biotech finds new ways to fight against time's toll, by David Stipp, in Fortune Magazine.
• Never say die, by Lisa Leff, in the Los Angeles Magazine.

Season of Birth and Human Longevity

Summary: Adult women over thirty live three years longer if they were born in May or December, rather than in August.

Interestingness: 2

Paper by Leonid A Gavrilov and Natalia S Gavrilova in the Journal of Anti-Aging Medicine, Volume 2, Issue 4, Winter 1999.

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Short two-page paper analysing a subset of the same data they used for their longevity vs fertility paper, ie European aristocratic families. In this case, they analysed a lot of variables until they found one that correlated with longevity.

On the relevant subsample of 4911 women, adult women over 30 born between 1800 and 1880 lived shortest if they were born in August and longest if they were born in May with the difference at about three and a half years. This is after correcting for a whole heap of variables that have nothing to do with month of birth but are related to longevity: year of birth, maternal and paternal life spans, age of parents at birth, birth order, nationality, whether the death was violent, loss of either or both parents before age twenty.

They have a graph and it doesn't look good to me. The only reasons I can think of, and that they propose, for the effect would be availability of vitamins (or calories but they are unlikely to be a problem for this group since they were all from aristocratic families) at specific points in the pregnancy or early life, but the graph is very noisy and it mostly jumps up and down. For example, the difference between July and August births is two and a bit years, and between August and September the difference is about a year and a half, with August at the minimum. The other bad months are February and March, on the other side of the year, with women born then living about a year longer than those in August. If the effect is real, then the critical periods during pregnancy must be very short.

I'm not buying any of it until it gets replicated.
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Adaptive Response to Swimming Exercise: Antioxidant Systems and Lipid Peroxidation

Summary: Anti-oxidant enzyme concentrations go up in the blood of rats that go swimming

Interestingness: 1

Paper by M Cesquini, MA Torsoni and SH Ogo in the Journal of Anti-Aging Medicine, Volume 2, Issue 4, Winter 1999.

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The abstract has everything covered. Note that these tests were on three groups of four rats each. Also, catalase was down on the endurance-trained group.
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Abstract follows:

Enzymatic and nonenzymatic antioxidants play an essential role in protecting tissues from oxidative damage during exercise. The present study investigated the levels of glutathione and antioxidant enzyme systems in the blood of unexercised and exercised (one bout of exhaustive swimming and adapted to swimming endurance training) rats. The hemoglobin concentration, hematocrit, and extent of oxidative injury to red blood cell (RBC) membranes were examined in the above groups of rats. The concentration of reduced glutathione (GSH) in the blood of exercised rats was about 30% higher than in the resting controls (0.40 Å [±] 0.12 GSH/Hb tetramer). Glutathione peroxidase (1.83 Å 0.24 X 102 IU/g Hb), glutathione reductase (1.73 Å 0.44 IU/g Hb), and Superoxide dismutase activities were significantly higher in both groups of exercised rats, whereas catalase activity (8.32 Å 1.04 X 104 IU/g Hb) was similar in the exercised and control animals. The hemoglobin concentration (11.8 g Hb/dL) and hematocrit (39.4%) increased with swimming exercise. Although lipid peroxidation is known to occur following physical exercise, the increased activity of the antioxidant enzymes and cell GSH levels in the present study were able to prevent lipid peroxidation of the RBC membrane. As a result, there was no significant variation in the plasma malondialdehyde levels among the three groups of rats. The redox capacity of the blood may have an important role in the organism in general since the redox status can be transferred across the RBC plasma membrane to other tissues. Exercise training is therefore beneficial to general health and protects cells against deleterious effects of reactive oxygen species produced during physical effort.

Pycnogenol Improves Learning Impairment and Memory Deficit in Senescence-Accelerated Mice

Summary: Senescence accelerated mice of the memory-impairment variety do better learning with pycnogenol.

Interestingness: 2

Paper by Fujun Liu, Yongxiang Zhang and Benjamin HS Lau in the Journal of Anti-Aging Medicine, Volume 2, Issue 4, Winter 1999.

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This is another one of those give substance to senescence accelerated mice (SAM) (see http://readingrejuvenationresearch.blogspot.com/2010/01/interventions-of-senescence-in-sam-mice.html), watch them act normal type papers. In this case, the substance, pycnogenol, was a commercial extract of the bark of the French maritime pine, which is made up mostly of procyanidins, which is the class of oligomers of flavonoids. The SAM chosen was SAMP8, which has mental issues. The task was learning. The SAMP8 did better when given the substance compared to controls, and about as well as the SAM resistant variety in these groups of 10 mice each. The suspected mechanism is anti-oxidant activity. Whoopee.

The interesting bit of the paper is the description of the memory experiments, which I'd heard mentioned before, as passive and active avoidance, but not described.

The passive avoidance tests are the if-you-move-I-shoot type, and they did two tests, called step-through and step-down. In the step-through test, mice are put in a bright area. There is a little tunnel to go to the dark area. Mice usually try to avoid being in a bright area, but when they go through the tunnel they get electrically shocked. If they don't go through on subsequent tests, it is assumed that they learnt. In the step-down test, they are put on a small rubber pad, surrounded by a sea of electric shock metallic mesh. If they stay on the pad for ten minutes, they "win".

The active avoidance test is, as expected, approximately the opposite. They are put in an area with two infrared beams that can be triggered. For ten seconds before the mesh below their feet becomes electrified, an alarm sounds and a light goes on, then the electricity is turned on for ten seconds. If they trigger both beams while the alarm is going on, either before or during the electric shock, the electricity is turned off. To trigger the beams they would have to run around.
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Abstract follows:

Pycnogenol (procyanidins extracted from the bark of French maritime pine, Pinus maritima Aiton) has been shown to be a potent free radical scavenger and an antioxidant phytochemical. The effects of pycnogenol on learning impairment and memory deficit in senescence-accelerated mouse (SAM) as a murine model of accelerated aging were determined. SAMP8, a strain of senescence-prone mice, exhibits immunodeficiency, hemopoietic dysfunction, learning impairment, and memory deficit. The effects of pycnogenol on learning performance and memory deficit were measured using step-through and step-down passive avoidance tests and shuttle box conditioned avoidance test. Oral feeding with pycnogenol for 2 months increased the retention rate in the step-through and the step-down tests and the rate of conditioned avoidance response in the shuttle box test. The latency of mice in the step-through test and the number of successful mice in the step-down test also increased with pycnogenol feeding. These results suggest that pycnogenol can improve learning impairment and memory deficit associated with aging.

Thyrotropin-Releasing Hormone Accelerates and Enhances the Age-Postponing Effects of Melatonin

Summary: Thyrotropin-releasing hormone (TRH) plus melatonin increase lifespan of old mice by three months

Interestingness: 4

Paper by Walter Pierpaoli, Daniele Bulian, Gordana Bulian and Gonzague Kistler in the Journal of Anti-Aging Medicine, Volume 2, Issue 4, Winter 1999.

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The sample size is small, 15 mice per group, but the effect size is interesting. The main table of results shows the following: for four groups of 15+-1 BALB/cJ female mice, 20 months old at the start of the experiment, a control group, one given melatonin, one TRH, one both, mean survival was 765+-54 days, 810+-50 days, 804+-80 days, and 861+-70 days respectively. There's also other results, with the TRH plus melatonin combination raising numbers of leukocytes and blood lymphocytes, and lowering cholesterol and triglycerides in old mice.

TRH induces release of thyrotropin, aka thyroid-stimulating hormone (TSH) which then induces the thyroid to release T3 and T4. Wikipedia has TRH being produced in the hypothalamus but the paper says it's produced by the hypothalamus and the pineal gland.

The mechanism behind this isn't precisely hypothesised but they do mention immune system upregulation. The authors hype TRH as the real reason for the supposed effects of melatonin on aging, saying that melatonin dosing stops the pineal gland making its own, so it can stay young and keep on making TRH later. TRH is also given as the explanation of why pineal gland transplantation from young to old mice, mentioned in http://readingrejuvenationresearch.blogspot.com/2010/03/perspective-on-proposed-association-of.html, increases the longevity of those mice.

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Abstract follows:

Studies over a period of several years have suggested an age-postponing effect of circadian nocturnal administration of melatonin and of young-to-old pineal grafting in rodents. Of the two procedures, the effect of pineal grafting was significantly more pronounced. Also, old-to-young and young-to-old pineal transplantation in normal or pinealectomized recipients suggested that the pineal itself contains the capacity to prevent or to accelerate the course of aging depending on the age of the donor and/or of a recipient when the pineal is transplanted. This observation prompted the idea that the "program of aging" might be governed by the capacity of the pineal to maintain the control of central neuroendocrine functions and to constantly synchronize the synthesis and release of hormones according to a strict circadian periodicity and seasonal rhythmicity. This report deals with the experimental evidence that, while melatonin alone exerts a low-level age-postponing activity, its age-delaying effects are greatly enhanced and accelerated when given in combination with a pineal peptide, thyrotropin-releasing hormone (TRH). This peptide may be a key element in the mechanism by which both melatonin and pineal grafting might postpone aging. In fact, as suggested by our data here, TRH could be one of the basic mediators in the brain (pineal-hypothalamic-hypophyseal axis) and in peripheral endocrine glands (e.g., the beta, insulin-producing cells in the pancreas). TRH may directly translate the light and temperature-mediated environmental stimuli into rapid energy-adapting biochemical processes which constantly monitor cell functions relating to energy production, in particular those required for thermoregulation. We show here that this energy-monitoring action of TRH is not thyroid mediated. We also show that TRH is not itself a toxic agent even when administered daily for long periods at a very high pharmacological dosage.

Effect of Carnosine on Age-Induced Changes in Senescence-Accelerated Mice

Summary: Carnosine extends median survival on an accelerated-aging model of mice by about 20%

Interestingness: 2

Paper by MO Yuneva, ER Bulygina, SC Gallant, GG Kramarenko, SL Stvolinsky, ML Semyonova and AA Boldyrev in the Journal of Anti-Aging Medicine, Volume 2, Issue 4, Winter 1999.

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In a study of two groups of 70 senescence-accelerated mice prone 1 (SAMP1) each, carnosine extended the time taken until half the mice in its group died. That is, on a plot of age versus percentage of animals alive, plotting both SAMP1 control and SAMP1 given carnosine groups, both curves start at 100% and drop to zero%. They reach zero at around the same age (17 months), but the control curve drops earlier, with the 50% mark being around 10 months for control and 12 months for the carnosine'd mice. Other benefits included glossier fur, less skin ulcers, and much more reactivity and passive avoidance. I don't know what reactivity is, but was in the group with passive avoidance. From wikipedia, I get that carnosine raises corticosterone. Doesn't sound good to me.

SAMP1 mice are whacked though, so again, I don't put much weight on this. SAMP1 mice are prone to amyloidoisis (http://readingrejuvenationresearch.blogspot.com/2010/01/interventions-of-senescence-in-sam-mice.html).

They don't know about the mechanism of action. They suggest a few: carnosine is a oxide radical scavenger, it prevents radical production in the first place, and it is an antiglycation agent, but maybe something else.

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Abstract follows:

The effect of carnosine on the life span and several brain biochemical characteristics in senescence-accelerated mice-prone 1 (SAMP1) was investigated. A 50% survival rate of animals treated with carnosine increased by 20% as compared to controls. Moreover, the number of animals that lived to an old age significantly increased. The effect of carnosine on life span was accompanied by a decrease in the level of 2'-tiobarbituric acid reactive substances (TBARS), monoamine oxidase b (MAO b), and Na/K-ATPase activity. There was also an increase in glutamate binding to N-methyl-D-aspartate receptors. These observations are consistent with the conclusion that carnosine increases life span and quality of life by diminishing production of lipid peroxides and reducing the influence of reactive oxygen species (ROS) on membrane proteins.

Impact of Dietary Restriction on Brain Aging and Neurodegenerative Disorders: Emerging Findings from Experimental and Epidemiological Studies

Summary: Calorie restriction helps mice and rat models of Alzheimer's, Parkinson's and stroke. 2-doxyglucose does too.

Interestingness: 2

Paper by Mark P Mattson in the Journal of Anti-Aging Medicine, Volume 2, Issue 4, Winter 1999.

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Rats and mice models of Alzheimer's disease (AD) did better when they were on a calorie restriction diet (CR). The same for Parkinson's disease (PD). Also for Huntington disease (HD). Also for rats given a stroke. I don't like the models, except the one for stroke, so I don't care much about these results.

They think this effect comes from over-expression of heat shock proteins (HSP-70) when glucose goes low. When given 2-deoxygluose (2-DG), a modified glucose that competes with glucose for the energy chain enzymes but is not able to be broken down properly (http://readingrejuvenationresearch.blogspot.com/2010/07/2-deoxy-d-glucose-feeding-in-rats.html), rats and mice also did better in the AD, PD and stroke models, even though they lived under all-you-can eat buffet conditions.

Finally, some lame-sounding correlation studies between caloric intake surveys with PD, AD and stroke are listed.
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Abstract follows:

Although dietary restriction (DR) extends life span and reduces levels of cellular oxidative stress in several different organ systems of laboratory rodents and monkeys, its impact on the brain is unknown. As is the case with age-related disorders in other organ systems (e.g., cardiovascular disease, diabetes, and many cancers), neurodegenerative disorders such as Alzheimer disease (AD), Parkinson disease (PD), and stroke involve increased levels of cellular oxidative stress and metabolic compromise. Recent studies of experimental rat and mouse models of AD, PD, and stroke have shown that DR increases resistance of neurons to dysfunction and degeneration. DR can attenuate age-related and disease-specific deficits in cognitive and motor functions in rodents. The available data suggest at least two possible mechanisms whereby DR protects neurons. One involves decreased levels of mitochondrial oxyradical production, and the second involves induction of the expression of "stress proteins" and neurotrophic factors. The latter mechanism is supported by data showing that the neuroprotective effect of DR can be mimicked by administration of 2-deoxyglucose to animals fed ad libitum. Recent findings in epidemiological studies of human populations suggest that individuals with a low daily calorie intake have reduced risk for AD and PD. Collectively, the available data suggest that DR may prove beneficial in reducing both the incidence and severity of neurodegenerative disorders in humans.

Rest of volume 2, Issue 3

The rest of issue 3 of 1999 consists of:

A review of the 28th Annual Meeting of the American Aging Association by RM Anson and MA Lane.

Two book reviews:

• "Understanding the process of aging: The roles of mitochondria, free radicals, and antioxidants", edited by Enrique Cadenas and Lester Packer. Very positive.
• "Towards prolongation of the healthy life span: Practical approaches to intervention", edited by Denham Harman, Robin Holliday and Mohsen Meydani. This is the collection of papers and posters for the 1997 meeting of the International Association of Biomedical Gerontology. Also very positive

The gerontology literature review:

• "Human embryonic stem-cell research: science and ethics", by Shirley J Wright, in American Scientist. Ethics of stem cell research.
• "Embryonic stem cells for medicine", by Roger A Pedersen, in Scientific American. Ethics of embryonic stem cells and cloning.

The usual other sections: literature watch and calendar. Web watch disappeared.

Formamidopyrimidine—DNA Glycosylase Targeted to Specific Organelles in C2C12 Cells

Summary: Targeting mitochondria or nucleus with an oxidised DNA base remover

Interestingness: 3

Paper by Karah A Street, Kerrie L. Hall, Patrick Murphy and Christi A Walter in the Journal of Anti-Aging Medicine, Volume 2, Issue 3, Fall 1999.

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The follow up paper to this one could be very interesting. This one seems to show that they could target either the mitochondria, or the nucleus with a protein, formamidopyrimidine-DNA glycosylase (Fpg), that gets rid of 2-deoxy-8-hydroxyguanine (8-OHdG), a screwed up version of the guanine base and the most common oxidised base. 8-OHdG causes the guanines (G) to be replaced by thymine (T) (by the normal repair mechanism I think). Fpg gets rid of 8-OHdG by taking out the base and leaving the ribose chain. This is supposedly a part of one of the normal DNA fixing mechanisms, called the base excision repair (BER), where one protein gets rid of a mutated base, and another goes and inserts the right base in.

So, yes, they created two DNA vectors, inserted them into some mouse muscle cells, and mostly saw what they were looking for, with the nuclear DNA being expressed mostly in the nucleus, and the mitochondrial in the cytoplasm. The levels of the molecule seemed pretty low though, and didn't correlate with the number of copies they inserted.

No assessment of the amount of 8-OHdG damage in the DNAs after transfection was done. I assume that's part of the plan for future work.
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Abstract follows:

Mitochondrial respiration provides a major source of energy for eukaryotic cells. However, the energy-producing processes also generate reactive oxygen species, which in turn damage mitochondrial DNA found in the mitochondrial matrix. Due to its locale, mitochondrial DNA is more susceptible to oxidative damage than nuclear DNA. While mitochondria do have some DNA repair capabilities, particularly base excision repair, oxidative damage persists in mitochondrial DNA. Correlations have been demonstrated between increasing age and increased levels of oxidative damage and mitochondrial DNA mutations. The current experiments were designed to begin to more directly delineate the role oxidative damage in mitochondrial DNA plays in aging. The mouse myoblast cell line, C2C12, was transfected with vectors, which express formamidopyrimidine-DNA glycosylase-myc fusion protein (Fpg-myc) and which contain either a mitochondrial or nuclear localization signal. Positive transfectants display expression of fpg at the mRNA level and exhibit an increase in Fpg activity in a whole-cell protein extract using a Fpg activity assay. Immunofluorescence analyses confirm that the transfected vectors have Fpg-myc appropriately targeted to mitochondria or nuclei. These cell lines with specifically targeted Fpg-myc expression provide the tools to test the effects of increasing the levels of a DNA glycosylase in mitochondria and nuclei on oxidative damage in DNA.

Centrophenoxine Slows Down, but Does Not Reverse, Lipofuscin Accumulation in Cultured Cells

Summary: Centrophenoxine is not very interesting with regards to lipofuscin

Interestingness: 1

Paper by Alexei Terman and Martin Welander in the Journal of Anti-Aging Medicine, Volume 2, Issue 3, Fall 1999.

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Lipofuscin is made up of the residues from lysosome degradation. Wikipedia claims it is the product of oxidised unsaturated fatty acids. It doesn't degrade with time in the body by itself, it just accumulates. The age-spots in old people are made of this.

Centrophenoxine is a treatement for senile dementia, which wikipedia claims improves memory and general cognition.

They tried using centrophenoxine to stop formation of, and to get rid of lipofuscin in rat heart cells exposed to high levels of oxigen (to accelerate lipofuscin production is my guess, since they only left it for a few weeks). It reduced formation by about half at what seems to me to be very high concentrations (almost a millimole), but did didly for removing already established lipofuscin particles or modifying number of autophagic vacuoles induced by leupeptin. They attribute the reduction effect on its anti-oxidant properties
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Abstract follows:

Centrophenoxine, a drug used in the treatment of senile dementia, has been suggested to retard, or even reverse, lipofuscin accumulation within postmitotic cells. However, a true capacity of centrophenoxine to eliminate already formed lipofuscin inclusions has not been convincingly demonstrated. Moreover, no evidence has been obtained regarding the possible mechanisms through which intracellular content of lipofuscin would be diminished by centrophenoxine. Here we show that (a) centrophenoxine at concentrations of 0.25 or 0.5 mM diminishes lipofuscin accumulation within cultured neonatal rat cardiac myocytes (by 44% or 51%, respectively, during a period of 2 weeks) when it was constantly present in the culture medium; (b) the same treatment of rat cardiac myocytes and AG-1518 human f ibroblasts, however, does not eliminate already formed lipofuscin inclusions; (c) the formation of autophagic vacuoles, and ensuing degradation of their contents, are not influenced by centrophenoxine. Thus, our results do not support the idea that centrophenoxine can reverse age-related accumulation of lipofuscin. The observed decrease of lipofuscin formation is probably due to the previously shown antioxidant properties of centrophenoxine.

Possible Influence of Metabolic Activity on Aging

Summary: Details of ATP production control mechanism in mitochondria

Interestingness: 4

Paper by Bernhard Kadenbach, Elisabeth Bender, Annette Reith, Andreas Becker, Shahla Hammerschmidt, Icksoo Lee, Susanne Arnold and Maik Hüttemann in the Journal of Anti-Aging Medicine, Volume 2, Issue 3, Fall 1999.

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This is more of a mitochondria biochem details piece, not directly related to aging. Most of it is too detailed for me to summarise or keep in memory or even follow.

Some interesting bits at the front that are not usually spelt out: out of the 13 proteins that mtDNA codes for, seven code for parts (out of 45) of NADH (nicotinamide adenine dinucleotide, protonated form) dehydrogenase (aka complex I), one for ubiquinol-cytochrome c oxidoreductase (aka complex III) (out of 11), three for cytochrome c oxidase (aka complex IV) (out of 13), and two for ATP synthase (out of some number I couldn't find). There's 5-10 mtDNA copies per mitochondrion, and 100-1000 mitochondria per cell.

It then describes two separate mechanisms of respiratory control. The first being due to the stimulation of ATP synthase by ADP triggering a lower proton motive force (deltaP) which trigger the proton pumps of the respiratory chain (NADH dehydrogenase, cytochrome c oxidoreductase and cytochrome c oxidase), kind of like an inverted system I think, with the final step pressuring the steps that come before it, but I imagine talking about the order here is completely wrong, they all happen at the same time. The second being due to the ATP/ADP ratio, with high ATP/ADP intramitochondrial ratio triggering a shut down of cytochrome c oxidase. This second method of control is bypassed by the presence of certain molecules, including 3,5-diiodo-L-thyronine, suggested as the mechanism of the short-term effects of thyoroid hormones, and palmitate (but not stearate, oleate or arachidonate).

The paper then does some studies showing that cAMP-dependent phosphorilation of complex IV enhances this ATP/ADP ratio control mechanism, and mitochondrial protein phosphatases reverse this enhancement. This second effect is shown mainly by adding a potassium fluoride which acts as a phosphatase inhibitor, and seeing the cAMP effect be stronger.

They also confirmed that it is mostly one mutant species of mtDNA that dominates a muscle fiber. They mapped a common deletion of mtDNA, probably that mtDNA4977 that was seen a couple of posts ago, and its occurrence varied between 0 and 0.06%, but corresponded with the bits of tissue that had malfunctioning complex IV.

They then speculate on how this phosphorilation/dephosphorilation mechanism is usually in balance, and is controlled by stressors and how when the ATP/ADP control mechanism is working, the proton gradient voltage is lower, and so less leakage of protons across the membrane occur, and less reactive oxide species are produced, and how this would be normally bypassed in a high caloric diet by the presence of palmitic acid, but the chain of reasoning is long and requires more concentration than I was willing to give it.

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Abstract follows:

The mitochondrial hypothesis on aging suggests stochastic stomatic mutations of mitochondrial DNA (mtDNA) as an important cause of respiratory-defective cells and the decline of energetic capabilities with increasing age. Reactive oxygen species (ROS), which are produced in the respiratory chain under stress conditions, are assumed to cause deletions and/or mutations of mtDNA. Using quantitative PCR, the stochastic distribution of the "common deletion" of mtDNA in human skeletal muscle tissue is shown. Recent data suggest that in vivo, under normal conditions, respiration is controlled by the intramitochondrial ATP/ADP ratio, via interaction of the nucleotides with subunit IV of cytochrome c oxidase, representing the rate-limiting step of the respiratory chain. Kinetic data are presented indicating that this "second mechanism of respiratory control" is turned on by cAMP-dependent phosphorylation of the enzyme and turned off by mitochondrial protein phosphatases. It is proposed that dephosphorylation of cytochrome c oxidase via "deleterious stress signals" results in increased mitochondrial membrane potentials and stimulated production of ROS in the mitochondrial respiratory chain. As a consequence, mutations of mtDNA would increase and aging would be accelerated. The inhibition of cytochrome c oxidase at high ATP/ADP ratios can also be abolished by low concentrations of free palmitate and high substrate pressure in the respiratory chain, supporting the notion that low caloric diet supports longevity.

Modeling the Role of Mitochondrial Mutations in Cellular Aging

Summary: Model of what happens if mitochondria with damaged DNA both reproduces and degrades slower than intact mitochondria, and how it fits observed data

Interestingness: 7

Paper by Axel Kowald and Thomas BL Kirkwood in the Journal of Anti-Aging Medicine, Volume 2, Issue 3, Fall 1999.

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They start by claiming there is a problem with the then-present theory of how damaged mitochondria are preferentially disseminated/take over cells by noting that it, the theory, is inconsistent with experimental results that show that damaged mitochondria is more prevalent in senescent cells than in dividing cells, and that the cells, or at least the muscle fibres, are taken over by one mutant type of mitochondria (by one I mean one type per case, not one common type for all cases) like we just saw in the last post http://readingrejuvenationresearch.blogspot.com/2010/12/segmental-nature-of-age-associated.html. Those are the main problems they want to see if they can patch with their model.

Their model starts at de Grey's model http://readingrejuvenationresearch.blogspot.com/2010/01/proposed-refinement-of-mitochondrial.html that basically hypothesises that mutant mitochondria produce less holes in their membranes and so are degraded less often. They justify the apparent contradiction in mutant mitochondria producing less holes with the "well known" fact that they produce more radicals by saying that most radicals are O2.- radicals but only the perhydroxy radical (HO2.-) can rip protons from lipids. Mutant mitochondria have a lower proton gradient so they produce lower amounts of HO2.- even if they produce more O2.-. Would seem good to get actual measurements, but they say that these aren't available and that they would be hard to get.

They, instead, produce a model with two assumptions: the first is that damaged mitochondria are destroyed slower than ones with intact mtDNA, and secondly, one introduced by them, that damaged mitochondria grow slower, which they justify by the energy shortage produced by the lower proton gradient. They split mitochondria into six groups, for little membrane damage, medium membrane damage and high membrane damage, each with intact mtDNA or mutant mtDNA. Radicals can increase the level of membrane damage or switch the mitochondria from an intact to a damaged mtDNA state. They give different turnover rates for mitochondria in each of the membrane damage classes, independent of their mtDNA state. The corresponding half lives for each damage class are 10, 2 and 1 week for low, medium and high damage. They used a factor of 2 as the increase in rate of free radicals that a mutant mitochondria produces compared to intact mitochondria, that mutants produced membrane damage at a rate 10 times lower than intact, and that intact grew 5 times quicker. I guess these numbers were half-guesses, and probably important in the results they got.

The model replicates the features from experiments they were looking to replicate, with one mutant taking over cells, and senescent cells having larger proportion of mutants than dividing cells, due to cell replication being a purifier of mitochondria. This purification happens because of the growth advantage of the intact mitochondria. This effect dominates when large amounts of mitochondria are to be produced, as in dividing cells, but the rate of destruction dominates when few mitochondria are being synthesised. They have some graphs showing what happens when the parameters are very different: if the mitochondria destruction rate are a bit lower, the population eventually collapses, if they are much higher, they collapse very quickly, along with other graphs showing the effects of different rates of cell reproduction and how that affects mitochondria population and stability (quick enough cell reproduction can fix higher rates of mutation).

From the model they also predict differences in importance between telomere shortening and mitochondrial damage in vivo vs in vitro. They claim that because in vitro conditions cells are replicated quickly, their collection of mitochondria will be pure through the process talked about above, so they will reach their Hayflick limit with nary an issue in their mitochondria, while in vivo, where cells replicate more slowly, mitochondrial damage will accumulate earlier and keeping telomeres long will not have an effect on cell lifespan.

(Interesting little factoid in the paper that I didn't fit in anywhere else: oxygen radicals are estimated to amount to 1-4% of consumed oxygen which sounded like a lot)

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Abstract follows:

The mitochondrial theory of aging suggests that an accumulation of defective mitochondria leads to loss of cell viability. The challenge is to explain how mitochondrial defects accumulate within cells, and why this process is more evident in postmitotic than in dividing cells. We describe a new mathematical model incorporating two critical features: (a) defective mitochondria are turned over more slowly than intact ones, and (b) defective mitochondria suffer a growth disadvantage. We also model the effect of cell division on the accumulation of defective mitochondria. The results support the mitochondrial theory and explain many of the observed data. The relationship of the mitochondrial theory to the suggested role of telomere loss in cell replicative senescence is discussed. We suggest that because of differences in the kinetics of their impact on cells, these two mechanisms have different relative importance for in vivo and in vitro cell aging.