2021-yousefzadeh.pdf: “An aged immune system drives senescence and ageing of solid organs”, (2021-05-12):
Ageing of the immune system, or immunosenescence, contributes to the morbidity and mortality of the elderly. To define the contribution of immune system ageing to organism ageing, here we selectively deleted Ercc1, which encodes a crucial DNA repair protein, in mouse hematopoietic cells to increase the burden of endogenous DNA damage and thereby senescence,, in the immune system only. We show that Vav-iCre+/
−;Ercc1−/ flmice were healthy into adulthood, then displayed premature onset of immunosenescence characterized by attrition and senescence of specific immune cell populations and impaired immune function, similar to changes that occur during ageing in wild-type mice,,. Notably, non-lymphoid organs also showed increased senescence and damage, which suggests that senescent, aged immune cells can promote systemic ageing. The transplantation of splenocytes from Vav-iCre+/ −;Ercc1−/ flor aged wild-type mice into young mice induced senescence in trans, whereas the transplantation of young immune cells attenuated senescence. The treatment of Vav-iCre+/ −;Ercc1−/ flmice with rapamycin reduced markers of senescence in immune cells and improved immune function. These data demonstrate that an aged, senescent immune system has a causal role in driving systemic ageing and therefore represents a key therapeutic target to extend healthy ageing.
2021-wiley.pdf: “Oxylipin biosynthesis reinforces cellular senescence and allows detection of senolysis”, (2021-04-02; ):
Senolytics—transgenic, and pharmacological interventions that selectively kill senescent cells—are currently in clinical trials aiming to treat age-related degenerative pathologies. Here, Wiley et al. discover that senescent cells produce multiple signaling lipids known as oxylipins. One oxylipin, dihomo-15d-PGJ2, promotes features of senescence by activating RAS and is released from cells during senolysis, serving as the first biomarker of the process in culture and in vivo.
- Senescent cells make several oxylipins, dihomo-prostaglandins, and leukotrienes
- Dihomo-15d-PGJ2 is intracellular during senescence and released during senolysis
- Dihomo-15d-PGJ2 activates RAS, promoting senescence and the SASP
- Positive feedback between prostaglandins, RAS, and p53 maintains senescence
Cellular senescence is a stress or damage response that causes a permanent proliferative arrest and secretion of numerous factors with potent biological activities. This senescence-associated secretory phenotype (SASP) has been characterized largely for secreted proteins that participate in embryogenesis, wound healing, inflammation, and many age-related pathologies. By contrast, lipid components of the SASP are understudied.
We show that senescent cells activate the biosynthesis of several oxylipins that promote segments of the SASP and reinforce the proliferative arrest. Notably, senescent cells synthesize and accumulate an unstudied intracellular prostaglandin, 1a,1b-dihomo-15-deoxy-delta-12,14-prostaglandin J2. Released 15-deoxy-delta-12,14-prostaglandin J2 is a biomarker of senolysis in culture and in vivo. This and other prostaglandin D2-related lipids promote the senescence arrest and SASP by activating RAS signaling.
These data identify an important aspect of cellular senescence and a method to detect senolysis.
[Keywords: cellular senescence, senescence, aging, lipids, metabolomics, eicosanoid, SASP, prostaglandin, dihomo-prostaglandin, biomarker, mass spectrometry, 15d-PGJ2, oxylipin, RAS]
[A universal biomarker measurable in blood for senolytics: “This biomarker is a unique signaling lipid metabolite, normally exclusively intracellular, but is released when senescent cells are forced to die.”]
2021-wadden.pdf: “Effect of Subcutaneous Semaglutide vs Placebo as an Adjunct to Intensive Behavioral Therapy on Body Weight in Adults With Overweight or Obesity: The STEP 3 Randomized Clinical Trial”, (2021-02-24; ):
- Question: In adults with overweight or obesity without diabetes, what effect does once-weekly subcutaneous semaglutide, 2.4 mg, have on body weight when added to intensive behavioral therapy with an initial low-calorie diet?
- Findings: In this randomized clinical trial that included 611 adults with overweight or obesity, 68 weeks’ treatment with once-weekly subcutaneous semaglutide vs placebo, combined with intensive behavioral therapy (and a low-calorie diet for the initial 8 weeks), resulted in reductions in body weight of 16.0% vs 5.7%, respectively; the difference was statistically-significant.
- Meaning: When used as an adjunct to intensive behavioral therapy and initial low-calorie diet, once-weekly subcutaneous semaglutide produced statistically-significantly greater weight loss than placebo during 68 weeks in adults with overweight or obesity.
Importance: Weight loss improves cardiometabolic risk factors in people with overweight or obesity. Intensive lifestyle intervention and pharmacotherapy are the most effective noninvasive weight loss approaches.
Objective: To compare the effects of once-weekly subcutaneous semaglutide, 2.4 mg vs placebo for weight management as an adjunct to intensive behavioral therapy with initial low-calorie diet in adults with overweight or obesity.
Design, Setting, and Participants: Randomized, double-blind, parallel-group, 68-week, phase 3a study (STEP 3) conducted at 41 sites in the US from August 2018 to April 2020 in adults without diabetes (n = 611) and with either overweight (body mass index ≥27) plus at least 1 comorbidity or obesity (body mass index ≥30).
Interventions: Participants were randomized (2:1) to semaglutide, 2.4 mg (n = 407) or placebo (n = 204), both combined with a low-calorie diet for the first 8 weeks and intensive behavioral therapy (ie, 30 counseling visits) during 68 weeks.
Main Outcomes and Measures: The co-primary end points were percentage change in body weight and the loss of 5% or more of baseline weight by week 68. Confirmatory secondary end points included losses of at least 10% or 15% of baseline weight.
Results: Of 611 randomized participants (495 women [81.0%], mean age 46 years [SD, 13], body weight 105.8 kg [SD, 22.9], and38.0 [SD, 6.7]), 567 (92.8%) completed the trial, and 505 (82.7%) were receiving treatment at trial end. At week 68, the estimated mean body weight change from baseline was −16.0% for semaglutide vs −5.7% for placebo (difference, −10.3 percentage points [95% CI, −12.0 to −8.6]; p < 0.001). More participants treated with semaglutide vs placebo lost at least 5% of baseline body weight (86.6% vs 47.6%, respectively; p < 0.001). A higher proportion of participants in the semaglutide vs placebo group achieved weight losses of at least 10% or 15% (75.3% vs 27.0% and 55.8% vs 13.2%, respectively; p < 0.001). Gastrointestinal adverse events were more frequent with semaglutide (82.8%) vs placebo (63.2%). Treatment was discontinued owing to these events in 3.4% of semaglutide participants vs 0% of placebo participants.
Conclusions and Relevance: Among adults with overweight or obesity, once-weekly subcutaneous semaglutide compared with placebo, used as an adjunct to intensive behavioral therapy and initial low-calorie diet, resulted in statistically-significantly greater weight loss during 68 weeks. Further research is needed to assess the durability of these findings.
Trial Registration: ClinicalTrials.gov Identifier: NCT03611582
2021-wilding.pdf: “Once-Weekly Semaglutide in Adults with Overweight or Obesity”, (2021-02-10; ):
Background: Obesity is a global health challenge with few pharmacologic options. Whether adults with obesity can achieve weight loss with once-weekly semaglutide at a dose of 2.4 mg as an adjunct to lifestyle intervention has not been confirmed.
Methods: In this double-blind trial, we enrolled 1961 adults with a body-mass index (the weight in kilograms divided by the square of the height in meters) of 30 or greater (≥27 in persons with ≥1 weight-related coexisting condition), who did not have diabetes, and randomly assigned them, in a 2:1 ratio, to 68 weeks [1.3 years] of treatment with once-weekly subcutaneous semaglutide (at a dose of 2.4 mg) or placebo, plus lifestyle intervention. The coprimary end points were the percentage change in body weight and weight reduction of at least 5%. The primary estimand (a precise description of the treatment effect reflecting the objective of the clinical trial) assessed effects regardless of treatment discontinuation or rescue interventions.
Results: The mean change in body weight from baseline to week 68 was −14.9% in the semaglutide group as compared with −2.4% with placebo, for an estimated treatment difference of −12.4 percentage points (95% confidence interval [CI], −13.4 to −11.5; p < 0.001). More participants in the semaglutide group than in the placebo group achieved weight reductions of 5% or more (1047 participants [86.4%] vs. 182 [31.5%]), 10% or more (838 [69.1%] vs. 69 [12.0%]), and 15% or more (612 [50.5%] vs. 28 [4.9%]) at week 68 (p < 0.001 for all three comparisons of odds). The change in body weight from baseline to week 68 was −15.3 kg in the semaglutide group as compared with −2.6 kg in the placebo group (estimated treatment difference, −12.7 kg; 95% CI, −13.7 to −11.7). Participants who received semaglutide had a greater improvement with respect to cardiometabolic risk factors and a greater increase in participant-reported physical functioning from baseline than those who received placebo. Nausea and diarrhea were the most common adverse events with semaglutide; they were typically transient and mild-to-moderate in severity and subsided with time. More participants in the semaglutide group than in the placebo group discontinued treatment owing to gastrointestinal events (59 [4.5%] vs. 5 [0.8%]).
Conclusions: In participants with overweight or obesity, 2.4 mg of semaglutide once weekly plus lifestyle intervention was associated with sustained, clinically relevant reduction in body weight. (Funded by Novo Nordisk; STEP 1 ClinicalTrials.gov number, NCT03548935).
2021-lennerz.pdf: “Carbohydrate restriction for diabetes: rediscovering centuries-old wisdom”, (2021-01-04):
Carbohydrate restriction, used since the 1700s to prolong survival in people with diabetes, fell out of favor after the discovery of insulin. Despite costly pharmacological and technological developments in the last few decades, current therapies do not achieve optimal outcomes, and most people with diabetes remain at high risk for microvascular and macrovascular complications. Recently, low-carbohydrate diets have regained popularity, with preliminary evidence of benefit for body weight, postprandial hyperglycemia, hyperinsulinemia, and other cardiometabolic risk factors in type 2 diabetes and, with more limited data, in type 1 diabetes. High-quality, long-term trials are needed to assess safety concerns and determine whether this old dietary approach might help people with diabetes attain clinical targets more effectively, and at a lower cost, than conventional treatment.
2020-pallauf.pdf: “The Potential of Resveratrol to Act as a Caloric Restriction Mimetic Appears to Be Limited: Insights from Studies in Mice”, (2020-12-03):
Caloric restriction (CR) has been shown repeatedly to prolong the lifespan in laboratory animals, with its benefits dependent on molecular targets forming part of the nutrient signaling network, including the NAD-dependent deacetylase silent mating type information regulation 2 homologue 1 (SIRT1). It has been hypothesized that the stilbene resveratrol (RSV) may counteract age-related and obesity-related diseases similarly to CR. In yeast and worms, RSV-promoted longevity also depended on SIRT1. While it remains unclear whether RSV can prolong lifespans in mammals, some studies in rodents supplemented with RSV have reported lowered body weight (BW) and fat mass, improved insulin sensitivity, lowered cholesterol levels, increased fitness, and mitochondrial biogenesis. Molecular mechanisms possibly leading to such changes include altered gene transcription and activation of SIRT1, AMP-activated kinase (AMPK), and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A). However, some mouse models did not benefit from RSV treatment to the same extent as others. We conducted a literature search on PubMed (15 April, 2020) for trials directly comparing RSV application to CR feeding in mice. In most studies retrieved by this systematic PubMed search, mice supplemented with RSV did not show statistically-significant reductions of BW, glucose, or insulin. Moreover, in some of these studies, RSV and CR treatments affected molecular targets differently and/
or findings on RSV and CR impacts varied between trials. We discuss those RSV-induced changes in gene transcription hypothesized to partly counteract age-related alterations. Although there may be a moderate effect of RSV supplementation on parameters such as insulin sensitivity toward a more CR-like profile in mice, data are inconsistent. Likewise, RSV supplementation trials in humans report controversial findings. While we consider that RSV may, under certain circumstances, moderately mimic some aspects of CR, current evidence does not fully support its use to prevent or treat age-related or obesity-related diseases.
2020-bischoffferrari.pdf: “Effect of Vitamin D Supplementation, Omega–3 Fatty Acid Supplementation, or a Strength-Training Exercise Program on Clinical Outcomes in Older Adults: The DO-HEALTH Randomized Clinical Trial”, (2020-11-10):
Question: Do vitamin D, omega-3, and a strength-training exercise program alone or in combination prevent 6 health outcomes among relatively healthy adults aged 70 years or older?
Findings: In this randomized trial that included 2157 adults aged 70 years or older, 3-year treatment with vitamin D3 (2000 IU/
d), with omega-3 fatty acids (1 g/ d), or with a strength-training exercise program did not result in statistically-significant differences in improvement in systolic or diastolic blood pressure, nonvertebral fractures, physical performance, infection rate, or cognition.
Meaning: These findings do not support the use of vitamin D, omega-3, or a strength-training exercise program for these clinical outcomes among relatively healthy older adults. Abstract
Importance: The benefits of vitamin D, omega-3 fatty acids, and exercise in disease prevention remain unclear.
Objective: To test whether vitamin D, omega-3s, and a strength-training exercise program, alone or in combination, improved 6 health outcomes among older adults.
Design, Setting, and Participants: Double-blind, placebo-controlled, 2 × 2 × 2 factorial randomized clinical trial among 2157 adults aged 70 years or older who had no major health events in the 5 years prior to enrollment and had sufficient mobility and good cognitive status. Patients were recruited between December 2012 and November 2014, and final follow-up was in November 2017.
Interventions: Participants were randomized to 3 years of intervention in 1 of the following 8 groups: 2000 IU/
d of vitamin D3, 1 g/ d of omega-3s, and a strength-training exercise program (n = 264); vitamin D3 and omega-3s (n = 265); vitamin D3 and exercise (n = 275); vitamin D3 alone (n = 272); omega-3s and exercise (n = 275); omega-3s alone (n = 269); exercise alone (n = 267); or placebo (n = 270).
Main Outcomes and Measures: The 6 primary outcomes were change in systolic and diastolic blood pressure (BP), Short Physical Performance Battery (SPPB), Montreal Cognitive Assessment (MoCA), and incidence rates (IRs) of nonvertebral fractures and infections over 3 years. Based on multiple comparisons of 6 primary end points, 99% confidence intervals are presented and p < 0.01 was required for statistical-significance.
Results: Among 2157 randomized participants (mean age, 74.9 years; 61.7% women), 1900 (88%) completed the study. Median follow-up was 2.99 years. Overall, there were no statistically-significant benefits of any intervention individually or in combination for the 6 end points at 3 years. For instance, the differences in mean change in systolic BP with vitamin D vs no vitamin D and with omega-3s vs no omega-3s were both −0.8 (99% CI, –2.1 to 0.5) mm Hg, with p < 0.13 and p < 0.11, respectively; the difference in mean change in diastolic BP with omega-3s vs no omega-3s was –0.5 (99% CI, –1.2 to 0.2) mm Hg; p = 0.06); and the difference in mean change in IR of infections with omega-3s vs no omega-3s was –0.13 (99% CI, –0.23 to –0.03), with an IR ratio of 0.89 (99% CI, 0.78–1.01; p = 0.02). No effects were found on the outcomes of SPPB, MoCA, and incidence of nonvertebral fractures). A total of 25 deaths were reported, with similar numbers in all treatment groups.
Conclusions and Relevance: Among adults without major comorbidities aged 70 years or older, treatment with vitamin D3, omega-3s, or a strength-training exercise program did not result in statistically-significant differences in improvement in systolic or diastolic blood pressure, nonvertebral fractures, physical performance, infection rates, or cognitive function. These findings do not support the effectiveness of these 3 interventions for these clinical outcomes.
Trial Registration: ClinicalTrials.gov Identifier: NCT01745263
2020-braude.pdf: “Surprisingly long survival of premature conclusions about naked mole-rat biology”, (2020-10-30):
Naked mole-rats express many unusual traits for such a small rodent. Their morphology, social behaviour, physiology, and ageing have been well studied over the past half-century. Many early findings and speculations about this subterranean species persist in the literature, although some have been repeatedly questioned or refuted. While the popularity of this species as a natural-history curiosity, and oversimplified story-telling in science journalism, might have fuelled the perpetuation of such misconceptions, an accurate understanding of their biology is especially important for this new biomedical model organism. We review 28 of these persistent myths about naked mole-rat sensory abilities, ecophysiology, social behaviour, development and ageing, and where possible we explain how these misunderstandings came about.
Ecophysiology and environment:
- naked mole-rats are hairless
- naked mole-rats are strictly subterranean and never go above ground
- naked mole-rats have unusually long burrows
- naked mole-rats are the only poikilothermic mammals
- naked mole-rats have uniquely low thyroid hormone levels
- naked mole-rat burrows are hypoxic and hypercapnic
- Naked mole-rats are blind
- naked mole-rats have degenerated hearing
- naked mole-rats are the most vocal rodents because they live in large groups
- naked mole-rats feel no pain
Social behaviour and reproduction:
- naked mole-rats are the only eusocial mammals
- colonies have castes of breeders and non-breeders, involving frequent workers, infrequent workers, non-workers, and dispersers
- colonies have up to three male breeders (pashas)
- colonies have a single queen
- not all females can become queens
- queens suppress workers with pheromones
- queens shove workers to get them to work
- naked mole-rats never leave their natal colonies
- naked mole-rats are inbred
Development, longevity, ageing and senescence:
- the GH/
IGF axis is impaired in naked mole-rats
- naked mole-rats are long-lived because they have low oxidative stress and damage
- naked mole-rat cells do not display cellular senescence
- naked mole-rats are immune to disease
- naked mole-rats do not get tumours or cancer
- naked mole-rats have extremely large hyaluronan
- naked mole-rat cells have early contact inhibition that prevents cancer
- naked mole-rats are non-ageing
- the GH/
- naked mole-rats are the single member of a taxonomic family
2020-grohn.pdf: “C60 in olive oil causes light-dependent toxicity and does not extend lifespan in mice”, (2020-10-29; ):
C60 is a potent antioxidant that has been reported to substantially extend the lifespan of rodents when formulated in olive oil (C60-OO) or extra virgin olive oil (C60-EVOO). Despite there being no regulated form of C60-OO, people have begun obtaining it from online sources and dosing it to themselves or their pets, presumably with the assumption of safety and efficacy. In this study, we obtain C60-OO from a sample of online vendors, and find marked discrepancies in appearance, impurity profile, concentration, and activity relative to pristine C60-OO formulated in-house. We additionally find that pristine C60-OO causes no acute toxicity in a rodent model but does form toxic species that can cause statistically-significant morbidity and mortality in mice in under 2 weeks when exposed to light levels consistent with ambient light. Intraperitoneal injections of C60-OO did not affect the lifespan of CB6F1 female mice. Finally, we conduct a lifespan and health span study in males and females C57BL/
6 J mice comparing oral treatment with pristine C60-EVOO and EVOO alone versus untreated controls. We failed to observe statistically-significant lifespan and health span benefits of C60-EVOO or EVOO supplementation compared to untreated controls, both starting the treatment in adult or old age. Our results call into question the biological benefit of C60-OO in aging.
2020-dorling.pdf: “Effects of caloric restriction on human physiological, psychological, and behavioral outcomes: highlights from CALERIE phase 2”, (2020-09-17; ):
Caloric restriction (CR) is a strategy that attenuates aging in multiple nonhuman species. The Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) trials are part of a research program aiming to test the effects of CR on aging and longevity biomarkers in humans. Building on CALERIE phase 1, CALERIE phase 2 (CALERIE 2) was the largest study to date to assess sustained CR in healthy humans without obesity. In a 24-month randomized controlled trial comprising 218 participants at baseline, CALERIE 2 showed that moderate CR, 11.9% on average, induced improvements in aging-related biomarkers without adversely affecting psychological or behavioral outcomes. The objectives of this report are to summarize and review the highlights of CALERIE 2 and report previously unpublished results on eating disorder symptoms and cognitive function. This article specifically summarizes the physiological, psychological, aging, behavioral, and safety results of the trial. Also provided are research directions beyond CALERIE 2 that highlight important opportunities to investigate the role of CR in aging, longevity, and health span in humans.
2020-partridge.pdf: “The quest to slow ageing through drug discovery”, (2020-05-28; ):
Although death is inevitable, individuals have long sought to alter the course of the ageing process. Indeed, ageing has proved to be modifiable; by intervening in biological systems, such as nutrient sensing, cellular senescence, the systemic environment and the gut microbiome, phenotypes of ageing can be slowed sufficiently to mitigate age-related functional decline. These interventions can also delay the onset of many disabling, chronic diseases, including cancer, cardiovascular disease and neurodegeneration, in animal models. Here, we examine the most promising interventions to slow ageing and group them into two tiers based on the robustness of the preclinical, and some clinical, results, in which the top tier includes rapamycin, senolytics, metformin, acarbose, spermidine, NAD+ enhancers and lithium. We then focus on the potential of the interventions and the feasibility of conducting clinical trials with these agents, with the overall aim of maintaining health for longer before the end of life.
2020-kushner.pdf: “Semaglutide 2.4 mg for the Treatment of Obesity: Key Elements of the STEP Trials 1 to 5”, (2020-05-22; ):
Objective: The obesity epidemic is a public health concern, warranting further research into pharmacological treatments for weight management (WM) as an adjunct to lifestyle interventions. The Semaglutide Treatment Effect in People with obesity (STEP) program aims to investigate the effect of semaglutide versus placebo on weight loss, safety, and tolerability in adults with obesity or overweight.
Methods: Across 5 phase 3 trials (NCT03548935, WM; NCT03552757, WM in type 2 diabetes; NCT03611582, WM with intensive behavioral therapy; NCT03548987, sustained WM; and NCT03693430, long-term WM), ~5,000 participants are being randomly assigned to receive semaglutide 2.4 mg once weekly subcutaneously versus placebo. Results will be available in 2020–2021. For all trials, the primary end point is change from baseline to end of treatment in body weight.
Results: Participants have a mean age of 46.2 to 55.3 years, are mostly female (mean: 74.1%–81.0%), and have a meanof 35.7 to 38.5 kg/
m2 and a mean waist circumference of 113.0 to 115.7 cm.
Conclusions: The STEP program evaluates the efficacy and safety of semaglutide 2.4 mg subcutaneously once weekly in a broad population. The trials will provide insights on WM in people with obesity with and without type 2 diabetes and on long-term follow-up.
2020-raj.pdf: “Current perspectives on the cellular and molecular features of epigenetic ageing”, (2020-04-10; ):
It has been noted for quite some time that DNA methylation levels decline with age. The importance of this change remained unknown until it became possible to measure methylation status of specific sites on the DNA.
It was observed that while the methylation of some sites does indeed decrease with age, that of others increase or remain unchanged. The application of machine learning methods to these quantitative changes in multiple sites, allowed the generation of a highly accurate estimator of age, called the epigenetic clock. The application of this clock on large human epidemiological data sets revealed that discordance between the predicted (epigenetic age) and chronological age is associated with many age-related pathologies, particularly when the former is greater than the latter. The epigenetic clock clearly captures to some degree, biological features that accompany the ageing process.
Despite the ever-increasing scope of pathologies that are found to be associated with accelerated epigenetic ageing, the basic principles that underlie the ticking of the clock remain elusive. Here, we describe the known molecular and cellular attributes of the clock and consider their properties, and proffer opinions as to how they may be connected and what might be the underlying mechanism. Emerging from these considerations is the inescapable view that epigenetic ageing begins from very early moments after the embryonic stem cell stage and continues un-interrupted through the entire life-course.
This appears to be a consequence of processes that are necessary for the development of the organism from conception and to maintain it thereafter through homeostasis. Hence, while the speed of ageing can, and is affected by external factors, the essence of the ageing process itself is an integral part of, and the consequence of the development of life.
Impact statement: The field of epigenetic ageing is relatively new, and the speed of its expansion presents a challenge in keeping abreast with new discoveries and their implications. Several reviews have already addressed the great number of pathologies, health conditions, life-style, and external stressors that are associated with changes to the rate of epigenetic ageing. While these associations highlight and affirm the ability of epigenetic clock to capture biologically meaningful changes associated with age, they do not inform us about the underlying mechanisms.
In this very early period since the development of the clock, there have been rather limited experimental research that are aimed at uncovering the mechanism. Hence, the perspective that we proffer is derived from available but nevertheless limited lines of evidence that together provide a seemingly coherent narrative that can be tested. This, we believe would be helpful towards uncovering the workings of the epigenetic clock.
2020-thau.pdf: “Cryonics for all?”, Tena Thau ( )
2014-bjelakovic-2.pdf: “Vitamin D supplementation for prevention of mortality in adults”, Bjelakovic G, Gluud LL, Nikolova D, Whitfield K, Wetterslev J, Simonetti RG, Bjelakovic M, Gluud C. ( )
2019-nauck.pdf: “Management Of Endocrine Disease: Are all GLP-1 agonists equal in the treatment of type 2 diabetes?”, (2019-12-01; ):
GLP-1, a peptide hormone secreted from the gut, stimulating insulin and suppressing glucagon secretion was identified as a parent compound for novel treatments of diabetes, but was degraded (dipeptidyl peptidase-4) and eliminated (mainly by kidneys) too fast (half-life 1–2 min) to be useful as a therapeutic agent. GLP-1 receptor agonist has been used to treat patients with type 2 diabetes since 2007, when exenatide (twice daily) was approved in 2007. Compounds with longer duration of action (once daily, once weekly) and with increasingly better efficacy with respect to glycemic control and body weight reduction have been developed, and in a recent ADA/
EASD consensus statement, were recommended as the first injectable diabetes therapy after failure of oral glucose-lowering medications.
Most GLP-1 receptor agonists (lixisenatide q.d., liraglutide q.d., exenatide q.w., dulaglutide q.w., albiglutide q.w., semaglutide q.w., all for s.c. injection, and the first oral preparation, oral semaglutide) have been examined in cardiovascular outcomes studies. Beyond proving their safety in vulnerable patients, most of whom had pre-existing heart disease, liraglutide, semaglutide, albiglutide, and dulaglutide reduced the time to first major adverse cardiovascular events (non-fatal myocardial infarction and stroke, cardiovascular death). Liraglutide, in addition, reduced cardiovascular and all-cause mortality.
It is the purpose of the present review to describe clinically important differences, regarding pharmacokinetic behaviour, glucose-lowering potency, effectiveness of reducing body weight and controlling other cardiovascular risk factors, and of the influence of GLP-1 receptor agonist treatment on cardiovascular outcomes in patients either presenting with or without pre-existing cardiovascular disease (atherosclerotic, ischemic or congestive heart failure).
…Recently, an oral preparation of semaglutide has been developed, which contains semaglutide (identical to the compound used for s.c. injection) and an absorption enhancer, Sodium N-(8-(2-hydroxybenzoyl) Amino) Caprylat (SNAC), which locally raises pH, prevents degradation of semaglutide, and facilitates absorption, most likely through gastric mucosa (28). Note that the bioavailability is still low, and much more peptide needs to be ingested to achieve similar plasma concentrations and efficacy (up to 14 mg per day as compared to 1 mg per week in the case of semaglutide for s.c. injection, ie. a 98-fold difference). To compensate for low and variable absorption, this oral preparation of semaglutide is recommended to be taken once daily. Predictable absorption and exposure to the drug requires it to be taken after an overnight fast with a small volume of water. A 30-min interval between the ingestion of the drug and the subsequent meal is required, before more fluid, food or other medications can be taken (28). Nevertheless, the development of an oral drug is a remarkable achievement and innovation.
2019-melzer.pdf: “The genetics of human ageing”, David Melzer, Luke C. Pilling, Luigi Ferrucci
2019-zeraatkar.pdf: “Effect of Lower Versus Higher Red Meat Intake on Cardiometabolic and Cancer Outcomes: A Systematic Review of Randomized Trials”, (2019-10-01; ):
Background: Few randomized trials have evaluated the effect of reducing red meat intake on clinically important outcomes.
Purpose: To summarize the effect of lower versus higher red meat intake on the incidence of cardiometabolic and cancer outcomes in adults.
Data Sources: EMBASE, CENTRAL, CINAHL, Web of Science, and ProQuest from inception to July 2018 and MEDLINE from inception to April 2019, without language restrictions.
Study Selection: Randomized trials (published in any language) comparing diets lower in red meat with diets higher in red meat that differed by a gradient of at least 1 serving per week for 6 months or more.
Data Extraction: Teams of 2 reviewers independently extracted data and assessed the risk of bias and the certainty of the evidence.
Data Synthesis: Of 12 eligible trials, a single trial enrolling 48 835 women provided the most credible, though still low-certainty, evidence that diets lower in red meat may have little or no effect on all-cause mortality (hazard ratio [HR], 0.99 [95% CI, 0.95 to 1.03]), cardiovascular mortality (HR, 0.98 [CI, 0.91 to 1.06]), and cardiovascular disease (HR, 0.99 [CI, 0.94 to 1.05]). That trial also provided low-certainty to very-low-certainty evidence that diets lower in red meat may have little or no effect on total cancer mortality (HR, 0.95 [CI, 0.89 to 1.01]) and the incidence of cancer, including colorectal cancer (HR, 1.04 [CI, 0.90 to 1.20]) and breast cancer (HR, 0.97 [0.90 to 1.04]).
Limitations: There were few trials, most addressing only surrogate outcomes, with heterogeneous comparators and small gradients in red meat consumption between lower versus higher intake groups.
Conclusion: Low-certainty to very-low-certainty evidence suggests that diets restricted in red meat may have little or no effect on major cardiometabolic outcomes and cancer mortality and incidence.
2019-aroda.pdf: “Comparative efficacy, safety, and cardiovascular outcomes with once-weekly subcutaneous semaglutide in the treatment of type 2 diabetes: Insights from the SUSTAIN 1–7 trials”, (2019-10-01; ):
In individuals with type 2 diabetes, glycemic control and cardiovascular risk factor management reduces the likelihood of late-stage diabetic complications. Guidelines recommend treatment goals targeting HbA1c, body weight, blood pressure, and low-density lipoprotein cholesterol. Development of new treatments for type 2 diabetes requires an understanding of their mechanism and efficacy, as well as their relative effects compared to other treatment choices, plus demonstration of cardiovascular safety.
Subcutaneous semaglutide is a glucagon-like peptide-1 receptor agonist currently approved in several countries for once-weekly treatment of type 2 diabetes. Semaglutide works via the incretin pathway, stimulating insulin and inhibiting glucagon secretion from the pancreatic islets, leading to lower blood glucose levels. Semaglutide also decreases energy intake by reducing appetite and food cravings, and lowering relative preference for fatty, energy-dense foods. Semaglutide was evaluated in the SUSTAIN clinical trial programme in over 8000 patients across the spectrum of type 2 diabetes. This review details the efficacy and safety profile of semaglutide in the SUSTAIN 1–5 and 7 trials, and its cardiovascular safety profile in the SUSTAIN 6 trial. Semaglutide consistently demonstrated superior and sustained glycemic control and weight loss vs. all comparators evaluated. In SUSTAIN 6, involving patients at high risk of cardiovascular disease, semaglutide statistically-significantly decreased the occurrence of cardiovascular events compared with placebo/
standard of care (hazard ratio 0.74, p < 0.001 for non-inferiority).
Through a comprehensive phase 3 clinical trial program, we have a detailed understanding of semaglutide’s efficacy, safety, cardiovascular effects and comparative role in the treatment of type 2 diabetes.
[Keywords: cardiovascular, efficacy, glucagon-like peptide-1 receptor agonist, semaglutide, SUSTAIN, type 2 diabetes]
2019-fahy.pdf: “TRIIM: Reversal of epigenetic aging and immunosenescent trends in humans”, (2019-09-08; ):
Epigenetic “clocks” can now surpass chronological age in accuracy for estimating biological age. Here, we use four such age estimators to show that epigenetic aging can be reversed in humans. Using a protocol intended to regenerate the thymus, we observed protective immunological changes, improved risk indices for many age-related diseases, and a mean epigenetic age approximately 1.5 years less than baseline after 1 year of treatment (−2.5-year change compared to no treatment at the end of the study). The rate of epigenetic aging reversal relative to chronological age accelerated from −1.6 year/
year from 0–9 month to −6.5 year/ year from 9–12 month. The GrimAge predictor of human morbidity and mortality showed a 2-year decrease in epigenetic vs. chronological age that persisted six months after discontinuing treatment. This is to our knowledge the first report of an increase, based on an epigenetic age estimator, in predicted human lifespan by means of a currently accessible aging intervention.
2019-vrselja.pdf: “Restoration of brain circulation and cellular functions hours post-mortem”, (2019-05-17; ):
The brains of humans and other mammals are highly vulnerable to interruptions in blood flow and decreases in oxygen levels. Here we describe the restoration and maintenance of microcirculation and molecular and cellular functions of the intact pig brain under ex vivo normothermic conditions up to four hours post-mortem. We have developed an extracorporeal pulsatile-perfusion system and a haemoglobin-based, acellular, non-coagulative, echogenic, and cytoprotective perfusate that promotes recovery from anoxia, reduces reperfusion injury, prevents oedema, and metabolically supports the energy requirements of the brain. With this system, we observed preservation of cytoarchitecture; attenuation of cell death; and restoration of vascular dilatory and glial inflammatory responses, spontaneous synaptic activity, and active cerebral metabolism in the absence of global electrocorticographic activity. These findings demonstrate that under appropriate conditions the isolated, intact large mammalian brain possesses an underappreciated capacity for restoration of microcirculation and molecular and cellular activity after a prolonged post-mortem interval.
2019-stambler.pdf: “What Do We Need to Know to Treat Degenerative Aging as a Medical Condition to Extend Healthy Lifespan?”, Ilia Stambler
2019-rose.pdf: “A longitudinal big data approach for precision health”, Sophia Miryam Schüssler-Fiorenza Rose, Kévin Contrepois, Kegan J. Moneghetti, Wenyu Zhou, Tejaswini Mishra, Samson Mataraso, Orit Dagan-Rosenfeld, Ariel B. Ganz, Jessilyn Dunn, Daniel Hornburg, Shannon Rego, Dalia Perelman, Sara Ahadi, M. Reza Sailani, Yanjiao Zhou, Shana R. Leopold, Jieming Chen, Melanie Ashland, Jeffrey W. Christle, Monika Avina, Patricia Limcaoco, Camilo Ruiz, Marilyn Tan, Atul J. Butte, George M. Weinstock, George M. Slavich, Erica Sodergren, Tracey L. McLaughlin, Francois Haddad, Michael P. Snyder
2019-mattson.pdf: “An Evolutionary Perspective on Why Food Overconsumption Impairs Cognition”, Mark P. Mattson
2019-mahmoudi.pdf: “Turning back time with emerging rejuvenation strategies”, Salah Mahmoudi, Lucy Xu, Anne Brunet
2019-cui.pdf: “Relaxed Selection Limits Lifespan by Increasing Mutation Load”, Rongfeng Cui, Tania Medeiros, David Willemsen, Leonardo N. M. Iasi, Glen E. Collier, Martin Graef, Martin Reichard, Dario Riccardo Valenzano
2018-oneil.pdf: “Efficacy and safety of semaglutide compared with liraglutide and placebo for weight loss in patients with obesity: a randomised, double-blind, placebo and active controlled, dose-ranging, phase 2 trial”, (2018-08-16; ):
Background: Obesity is a major public health issue, and new pharmaceuticals for weight management are needed. Therefore, we evaluated the efficacy and safety of the glucagon-like peptide-1 (GLP-1) analogue semaglutide in comparison with liraglutide and a placebo in promoting weight loss.
Methods: We did a randomised, double-blind, placebo and active controlled, multicentre, dose-ranging, phase 2 trial. The study was done in eight countries involving 71 clinical sites. Eligible participants were adults (≥18 years) without diabetes and with a body-mass index () of 30 kg/
m2 or more. We randomly assigned participants (6:1) to each active treatment group (ie, semaglutide [0·05 mg, 0·1 mg, 0·2 mg, 0·3 mg, or 0·4 mg; initiated at 0·05 mg per day and incrementally escalated every 4 weeks] or liraglutide [3·0 mg; initiated at 0·6 mg per day and escalated by 0·6 mg per week]) or matching placebo group (equal injection volume and escalation schedule to active treatment group) using a block size of 56. All treatment doses were delivered once-daily via subcutaneous injections. Participants and investigators were masked to the assigned study treatment but not the target dose. The primary endpoint was percentage weight loss at week 52. The primary analysis was done using intention-to-treat ANCOVA estimation with missing data derived from the placebo pool. This study is registered with ClinicalTrials.gov, number NCT02453711.
Findings: Between Oct 1, 2015, and Feb 11, 2016, 957 individuals were randomly assigned (102–103 participants per active treatment group and 136 in the pooled placebo group). Mean baseline characteristics included age 47 years, bodyweight 111·5 kg, and39·3 kg/
m2. Bodyweight data were available for 891 (93%) of 957 participants at week 52. Estimated mean weight loss was −2·3% for the placebo group versus −6·0% (0·05 mg), −8·6% (0·1 mg), −11·6% (0·2 mg), −11·2% (0·3 mg), and −13·8% (0·4 mg) for the semaglutide groups. All semaglutide groups versus placebo were statistically-significant (unadjusted p≤0·0010), and remained statistically-significant after adjustment for multiple testing (p≤0·0055). Mean bodyweight reductions for 0·2 mg or more of semaglutide versus liraglutide were all statistically-significant (−13·8% to −11·2% vs −7·8%). Estimated weight loss of 10% or more occurred in 10% of participants receiving placebo compared with 37–65% receiving 0·1 mg or more of semaglutide (p <0·0001 vs placebo). All semaglutide doses were generally well tolerated, with no new safety concerns. The most common adverse events were dose-related gastrointestinal symptoms, primarily nausea, as seen previously with GLP-1 receptor agonists.
Interpretation: In combination with dietary and physical activity counselling, semaglutide was well tolerated over 52 weeks and showed clinically relevant weight loss compared with placebo at all doses.
Funding: Novo Nordisk A/
2018-xu.pdf: “Senolytics improve physical function and increase lifespan in old age”, Ming Xu, Tamar Pirtskhalava, Joshua N. Farr, Bettina M. Weigand, Allyson K. Palmer, Megan M. Weivoda, Christina L. Inman, Mikolaj B. Ogrodnik, Christine M. Hachfeld, Daniel G. Fraser, Jennifer L. Onken, Kurt O. Johnson, Grace C. Verzosa, Larissa G. P. Langhi, Moritz Weigl, Nino Giorgadze, Nathan K. LeBrasseur, Jordan D. Miller, Diana Jurk, Ravinder J. Singh, David B. Allison, Keisuke Ejima, Gene B. Hubbard, Yuji Ikeno, Hajrunisa Cubro, Vesna D. Garovic, Xiaonan Hou, S. John Weroha, Paul D. Robbins, Laura J. Niedernhofer, Sundeep Khosla, Tamara Tchkonia, James L. Kirkland ( )
2018-sutton.pdf: “Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes”, Elizabeth F. Sutton, Robbie Beyl, Kate S. Early, William T. Cefalu, Eric Ravussin, Courtney M. Peterson
2018-leidal.pdf: “Autophagy and the cell biology of age-related disease”, Andrew M. Leidal, Beth Levine, Jayanta Debnath
2018-gardner.pdf: “Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin SecretionThe DIETFITS Randomized Clinical Trial”, American Medical Association
2017-blundell.pdf: “Effects of once-weekly semaglutide on appetite, energy intake, control of eating, food preference and body weight in subjects with obesity”, (2017-03-07; ):
Aim: The aim of this trial was to investigate the mechanism of action for body weight loss with semaglutide.
Materials and methods: This randomised, double-blind, placebo-controlled, two-period crossover trial investigated the effects of 12 weeks of treatment with once-weekly subcutaneous semaglutide, dose-escalated to 1.0 mg, in 30 subjects with obesity. Ad libitum energy intake, ratings of appetite, thirst, nausea and well-being, control of eating, food preference, resting metabolic rate, body weight and body composition were assessed.
Results: After a standardised breakfast, semaglutide, compared with placebo, led to a lower ad libitum energy intake during lunch (−1255 kJ; p < 0.0001) and during the subsequent evening meal (p = 0.0401) and snacks (p = 0.0034), resulting in a 24% reduction in total energy intake across all ad libitum meals throughout the day (−3036 kJ; p < 0.0001). Fasting overall appetite suppression scores were improved with semaglutide vs placebo, while nausea ratings were similar. Semaglutide was associated with less hunger and food cravings, better control of eating and a lower preference for high-fat foods. Resting metabolic rate, adjusted for lean body mass, did not differ between treatments. Semaglutide led to a reduction from baseline in mean body weight of 5.0 kg, predominantly from body fat mass.
Conclusion: After 12 weeks of treatment, ad libitum energy intake was substantially lower with semaglutide vs placebo with a corresponding loss of body weight observed with semaglutide. In addition to reduced energy intake, likely mechanisms for semaglutide-induced weight loss included less appetite and food cravings, better control of eating and lower relative preference for fatty, energy-dense foods.
Video Abstract: A free Video Abstract to accompany this article is available.
2017-weir.pdf: “Dietary Restriction and AMPK Increase Lifespan via Mitochondrial Network and Peroxisome Remodeling”, Heather J. Weir, Pallas Yao, Frank K. Huynh, Caroline C. Escoubas, Renata L. Goncalves, Kristopher Burkewitz, Raymond Laboy, Matthew D. Hirschey, William B. Mair
2017-trepanowski.pdf: “Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese AdultsA Randomized Clinical Trial”, American Medical Association ( )
2017-li.pdf: “Intermittent Fasting Promotes White Adipose Browning and Decreases Obesity by Shaping the Gut Microbiota”, Guolin Li, Cen Xie, Siyu Lu, Robert G. Nichols, Yuan Tian, Licen Li, Daxeshkumar Patel, Yinyan Ma, Chad N. Brocker, Tingting Yan, Kristopher W. Krausz, Rong Xiang, Oksana Gavrilova, Andrew D. Patterson, Frank J. Gonzalez
2017-campbell.pdf: “Metformin reduces all-cause mortality and diseases of ageing independent of its effect on diabetes control: a systematic review and meta-analysis”, Jared M. Campbell, Susan M. Bellman, Matthew D. Stephenson, Karolina Lisy. ( )
2017-mcveigh.pdf: “2,4–Dinitrophenol, the inferno drug: a netnographic study of user experiences in the quest for leanness”, (2017):
Background: Despite not being licensed for human consumption, the Internet has triggered renewed, widespread interest and availability of 2,4-Dinitrophenol (DNP). DNP, a cellular metabolic poison, causes thermogenesis resulting in fat burning and weight loss. Whilst extensively available for purchase online, research on user experiences of DNP is limited.
Methods: A netnographic approach was used to describe user experiences of DNP via online public websites. Public websites discussing DNP were identified and a purposeful sample selected. Discussion threads were downloaded and a textual qualitative analysis conducted. Four themes containing 71 categories were generated.
Results: There exists a plethora of communal folk pharmacological advice and recommendations for DNP manufacture and use, together with associated harms and outcomes. The efficacy and untoward effects of DNP were described and discussed alongside the notion that DNP should only be used by experienced bodybuilders. Dosage and regimes for optimal use were also described.
Conclusion: This unique study provides a rich examination of the knowledge, attitudes, and motivations of DNP users, illustrating the important role of online public websites in sharing information. Further understanding of DNP users and the online communities in which they reside is warranted to facilitate engagement and formulate appropriate and effective policy responses.
[Keywords: 2,4-Dinitrophenol, DNP, fat burn, Internet]
2016-nauck.pdf: “A Phase 2, Randomized, Dose-Finding Study of the Novel Once-Weekly Human GLP-1 Analog, Semaglutide, Compared With Placebo and Open-Label Liraglutide in Patients With Type 2 Diabetes”, (2016-02-01; ):
Objective: To investigate the dose-response relationship of semaglutide versus placebo and open-label liraglutide in terms of glycemic control in patients with type 2 diabetes.
Research Design And Methods: This was a 12-week, randomized, double-blind phase 2 trial. Patients (n = 415) were randomized to receive a subcutaneous injection of semaglutide once weekly without dose escalation (0.1–0.8 mg) or with dose escalation (E) (0.4 mg steps to 0.8 or 1.6 mg E over 1–2 weeks), open-label liraglutide once daily (1.2 or 1.8 mg), or placebo. The primary end point was change in HbA1c level from baseline. Secondary end points included change in body weight, safety, and tolerability.
Results: Semaglutide dose-dependently reduced the level of HbA1c from baseline (8.1 ± 0.8%) to week 12 by up to −1.7%, and body weight by up to −4.8 kg (1.6 mg E, p < 0.001 vs. placebo). Up to 81% of patients achieved an HbA1c level of <7%. HbA1c level and weight reductions with semaglutide 1.6 mg E were greater than those with liraglutide 1.2 and 1.8 mg (based on unadjusted CIs), but adverse events (AEs) and withdrawals occurred more frequently. The incidence of nausea, vomiting, and withdrawal due to gastrointestinal AEs increased with the semaglutide dose; most events were mild to moderate, transient, and ameliorated by dose escalation. There were no major episodes of hypoglycemia and few cases of injection site reactions.
Conclusions: After 12 weeks, semaglutide dose-dependently reduced HbA1c level and weight in patients with type 2 diabetes. No unexpected safety or tolerability concerns were identified; gastrointestinal AEs typical of glucagon-like peptide 1 receptor agonists were mitigated by dose escalation. On this basis, weekly semaglutide doses of 0.5 and 1.0 mg with a 4-week dose escalation were selected for phase 3.
2016-tinsley.pdf: “Time-restricted feeding in young men performing resistance training: A randomized controlled trial†”, GRANT M. TINSLEY
2016-moon.pdf: “Safe landing strategies during a fall: Systemic review and meta-analysis”, Yaejin Moon, Jacob J. Sosnoff, ( )
2016-barzilai.pdf: “Metformin as a Tool to Target Aging”, Nir Barzilai, Jill P. Crandall, Stephen B. Kritchevsky, Mark A. Espeland ( )
2015-lau.pdf: “Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide”, (2015-08-26; ):
Liraglutide is an acylated glucagon-like peptide-1 (GLP-1) analogue that binds to serum albumin in vivo and is approved for once-daily treatment of diabetes as well as obesity.
The aim of the present studies was to design a once weekly GLP-1 analogue by increasing albumin affinity and secure full stability against metabolic degradation. The fatty acid moiety and the linking chemistry to GLP-1 were the key features to secure high albumin affinity and GLP-1 receptor (GLP-1R) potency and in obtaining a prolonged exposure and action of the GLP-1 analogue.
Semaglutide was selected as the optimal once weekly candidate. Semaglutide has two amino acid substitutions compared to human GLP-1 (Aib8, Arg34) and is derivatized at lysine 26. The GLP-1R affinity of semaglutide (0.38 ± 0.06 nM) was three-fold decreased compared to liraglutide, whereas the albumin affinity was increased. The plasma half-life was 46.1 h in mini-pigs following i.v. administration, and semaglutide has an MRT of 63.6 h after s.c. dosing to mini-pigs.
Semaglutide is currently in phase 3 clinical testing.
2015-brandhorst.pdf: “A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan”, Sebastian Brandhorst, In Young Choi, Min Wei, Chia Wei Cheng, Sargis Sedrakyan, Gerardo Navarrete, Louis Dubeau, Li Peng Yap, Ryan Park, Manlio Vinciguerra, Stefano Di Biase, Hamed Mirzaei, Mario G. Mirisola, Patra Childress, Lingyun Ji, Susan Groshen, Fabio Penna, Patrizio Odetti, Laura Perin, Peter S. Conti, Yuji Ikeno, Brian K. Kennedy, Pinchas Cohen, Todd E. Morgan, Tanya B. Dorff, Valter D. Longo ( )
2014-avenell.pdf: “Vitamin D and vitamin D analogues for preventing fractures in post‐menopausal women and older men”, (2014-04-14; ):
Background: Vitamin D and related compounds have been used to prevent osteoporotic fractures in older people. This is the third update of a Cochrane review first published in 1996.
Objectives: To determine the effects of vitamin D or related compounds, with or without calcium, for preventing fractures in post-menopausal women and older men.
Search methods: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (to December 2012), the Cochrane Central Register of Controlled Trials (2012, Issue 12), MEDLINE (1966 to November Week 3 2012), EMBASE (1980 to 2012 Week 50), CINAHL (1982 to December 2012), BIOSIS (1985 to 2013-01-03), Current Controlled Trials (December 2012) and reference lists of articles.
Selection criteria: Randomised or quasi-randomised trials that compared vitamin D or related compounds, alone or with calcium, against placebo, no intervention or calcium alone, and that reported fracture outcomes in older people. The primary outcome was hip fracture. Data collection and analysis
Two authors independently assessed trial risk of selection bias and aspects of methodological quality, and extracted data. Data were pooled, where possible, using the fixed-effect model, or the random-effects model when heterogeneity between studies appeared substantial. Main results
We included 53 trials with a total of 91,791 participants. Thirty-one trials, with sample sizes ranging from 70 to 36,282 participants, examined vitamin D (including 25-hydroxy vitamin D) with or without calcium in the prevention of fractures in community, nursing home or hospital inpatient populations. Twelve of these 31 trials had participants with a mean or median age of 80 years or over.
Another group of 22 smaller trials examined calcitriol or alfacalcidol (1-alphahydroxyvitamin D3), mostly with participants who had established osteoporosis. These trials were carried out in the setting of institutional referral clinics or hospitals.
In the assessment of risk of bias for random sequence generation, 21 trials (40%) were deemed to be at low risk, 28 trials (53%) at unclear risk and four trials at high risk (8%). For allocation concealment, 22 trials were at low risk (42%), 29 trials were at unclear risk (55%) and two trials were at high risk (4%).
There is high quality evidence that vitamin D alone, in the formats and doses tested, is unlikely to be effective in preventing hip fracture (11 trials, 27,693 participants; risk ratio (RR) 1.12, 95% confidence intervals (CI) 0.98 to 1.29) or any new fracture (15 trials, 28,271 participants; RR 1.03, 95% CI 0.96 to 1.11).
There is high quality evidence that vitamin D plus calcium results in a small reduction in hip fracture risk (nine trials, 49,853 participants; RR 0.84, 95% confidence interval (CI) 0.74 to 0.96; P value 0.01). In low-risk populations (residents in the community: with an estimated eight hip fractures per 1000 per year), this equates to one fewer hip fracture per 1000 older adults per year (95% CI 0 to 2). In high risk populations (residents in institutions: with an estimated 54 hip fractures per 1000 per year), this equates to nine fewer hip fractures per 1000 older adults per year (95% CI 2 to 14).
There is high quality evidence that vitamin D plus calcium is associated with a statistically-significant reduction in incidence of new non-vertebral fractures. However, there is only moderate quality evidence of an absence of a statistically-significant preventive effect on clinical vertebral fractures. There is high quality evidence that vitamin D plus calcium reduces the risk of any type of fracture (10 trials, 49,976 participants; RR 0.95, 95% CI 0.90 to 0.99).
In terms of the results for adverse effects: mortality was not adversely affected by either vitamin D or vitamin D plus calcium supplementation (29 trials, 71,032 participants, RR 0.97, 95% CI 0.93 to 1.01). Hypercalcaemia, which was usually mild (2.6 to 2.8 mmol/
L), was more common in people receiving vitamin D or an analogue, with or without calcium (21 trials, 17,124 participants, RR 2.28, 95% CI 1.57 to 3.31), especially for calcitriol (four trials, 988 participants, RR 4.41, 95% CI 2.14 to 9.09), than in people receiving placebo or control. There was also a small increased risk of gastrointestinal symptoms (15 trials, 47,761 participants, RR 1.04, 95% CI 1.00 to 1.08), especially for calcium plus vitamin D (four trials, 40,524 participants, RR 1.05, 95% CI 1.01 to 1.09), and a statistically-significant increase in renal disease (11 trials, 46,548 participants, RR 1.16, 95% CI 1.02 to 1.33). Other systematic reviews have found an increased association of myocardial infarction with supplemental calcium; and evidence of increased myocardial infarction and stroke, but decreased cancer, with supplemental calcium plus vitamin D, without an overall effect on mortality.
Authors’ conclusions: Vitamin D alone is unlikely to prevent fractures in the doses and formulations tested so far in older people. Supplements of vitamin D and calcium may prevent hip or any type of fracture. There was a small but statistically-significant increase in gastrointestinal symptoms and renal disease associated with vitamin D and calcium. This review found that there was no increased risk of death from taking calcium and vitamin D.
2014-dean.pdf: “Dr Ward Dean Q&A [on Johan Bjorksten]”, Ward Dean ( )
2014-bjelakovic.pdf: “Vitamin D supplementation for prevention of cancer in adults (Review)”, Bjelakovic G, Gluud LL, Nikolova D, Whitfield K, Krstic G, Wetterslev J, Gluud C ( )
2011-teng.pdf: “Efficacy of fasting calorie restriction on quality of life among aging men”, Nur Islami Mohd Fahmi Teng, Suzana Shahar, Zahara Abdul Manaf, Sai Krupa Das, Che Suhaili Che Taha, Wan Zurinah Wan Ngah ( )
2011-elamin.pdf: “Vitamin D and Cardiovascular Outcomes: A Systematic Review and Meta–Analysis”, (2011-07-01; ):
Context: Several studies found association between vitamin D levels and hypertension, coronary artery calcification, and heart disease.
Objective: The aim of this study was to summarize the evidence on the effect of vitamin D on cardiovascular outcomes.
Design and Methods: We searched electronic databases from inception through August 2010 for randomized trials. Reviewers working in duplicate and independently extracted study characteristics, quality, and the outcomes of interest. Random-effects meta-analysis was used to pool the relative risks (RR) and the weighted mean differences across trials.
Results: We found 51 eligible trials with moderate quality. Vitamin D was associated with nonsignificant effects on the patient-important outcomes of death [RR, 0.96; 95% confidence interval (CI), 0.93, 1.00; p = 0.08], myocardial infarction (RR, 1.02; 95% CI, 0.93, 1.13; p = 0.64), and stroke (RR, 1.05; 95% CI, 0.88, 1.25; p = 0.59). These analyses were associated with minimal heterogeneity. There were no statistically-significant changes in the surrogate outcomes of lipid fractions, glucose, or diastolic or systolic blood pressure. The latter analyses were associated with statistically-significant heterogeneity, and the pooled estimates were trivial in absolute terms.
Conclusions: Trial data available to date are unable to demonstrate a statistically-significant reduction in mortality and cardiovascular risk associated with vitamin D. The quality of the available evidence is low to moderate at best.
Incretin-based therapies, such as the injectable glucagon-like peptide-1 (GLP-1) receptor agonists and orally administered dipeptidyl peptidase-4 (DPP-4) inhibitors, have recently been introduced into clinical practice.
At present, the GLP-1 receptor agonists need to be administered once or twice daily. Several once-weekly GLP-1 receptor agonists are in phase 3 development. This review examines the efficacy, safety and perspective for the future of the once-weekly GLP-1 receptor agonists: exenatide once weekly, taspoglutide, albiglutide, LY2189265 and CJC-1134-PC, and compared them to the currently available agonists, exenatide BID and liraglutide QD.
A greater reduction in haemoglobin A1c (HbA1c) and fasting plasma glucose was found with the once-weekly GLP-1 receptor agonists compared with exenatide BID, while the effect on postprandial hyperglycemia was modest with the once-weekly GLP-1 receptor agonist. The reduction in HbA1c was in most studies greater compared to oral antidiabetic drugs and insulin glargine. The reduction in weight did not differ between the short-acting and long-acting agonists.
The gastrointestinal side effects were less with the once-weekly agonists compared with exenatide BID, except for taspoglutide. Antibodies seem to be most frequent with exenatide once weekly, while hypersensitivity has been described in few patients treated with taspoglutide. Injection site reactions differ among the long-acting GLP-1 receptor agonists and are observed more frequently than with exenatide BID and liraglutide. In humans, no signal has been found indicating an association between the once-weekly agonists and C-cell cancer. The cardiovascular safety, durability of glucose control and effect on weight will emerge from several ongoing major long-term trials.
The once-weekly GLP-1 receptor analogues are promising candidates for the treatment of type 2 diabetes, although their efficacy may not be superior to once-daily analogue liraglutide.
2011-bulterijs.pdf: “Metformin As a Geroprotector”, Sven Bulterijs ( )
2012-agueda.pdf: “Association of circulating visfatin concentrations with insulin resistance and low–grade inflammation after dietary energy restriction in Spanish obese non–diabetic women: Role of body composition changes”, (2010-10-15):
Background and Aims: To assess the influence of body composition changes on circulating serum visfatin after following 12 weeks of energy restricted diet intervention. We also examined the possible role of visfatin in glucose metabolism and in obesity-associated low-grade inflammation.
Methods and Results: A total of 78 obese (34.0 ± 2.8 kg/
m2) women aged 36.7±7 y volunteered to participate in the study. We measured by DXA body fat mass (FM) and lean mass (LM). Fasting serum visfatin, glucose, insulin, adiponectin, leptin, IL-1β, IL-6, IL-8, TNF-α and CRP concentrations were analyzed before and after the intervention and HOMA and QUIKI indexes were calculated. Mean weight loss 7.7 ± 3.0 kg and HOMA decreased in 24 ± 35%. Serum visfatin concentration change was negatively associated with LM difference (p < 0.05), whereas no statistically-significant relationship was observed with FM changes after energy restricted diet intervention. Changes in circulating serum visfatin levels were statistically-significantly and inversely associated with HOMA-IR (p < 0.01) and positively with QUICKI index (p < 0.02) after energy restricted diet intervention, regardless of achieved body weight loss. We did not find any statistically-significant association between changes in visfatin levels and IL-1β, IL-6, IL-8, TNF-α and CRP levels after dietary intervention (all p > 0.2).
Conclusion: Circulating visfatin concentration is associated with sensitivity improvement achieved after energy restricted diet intervention induced weight loss. Furthermore, LM changes could be an influencing factor on visfatin concentrations and consequently, on the improvement of insulin sensitivity after weight loss in obese non-diabetic women. Our findings did not provide any evidence for a role of visfatin increase on low-grade inflammation after weight loss.
[Keywords: visfatin, weight loss, obesity, insulin resistance, inflammation]
2010-stannard.pdf: “Adaptations to skeletal muscle with endurance exercise training in the acutely fed versus overnight-fasted state”, Stephen R. Stannard, Alex J. Buckley, Johann A. Edge, Martin W. Thompson ( )
2008-zhu.pdf: “Effects of Calcium and Vitamin D Supplementation on Hip Bone Mineral Density and Calcium–Related Analytes in Elderly Ambulatory Australian Women: A Five–Year Randomized Controlled Trial”, (2008-03-01; ):
Context: Effects of long-term calcium, with or without vitamin D, on hip bone mineral density (BMD) and bone turnover in sunny climates have not been reported.
Objective: The aim was to evaluate the effect of vitamin D added to calcium supplementation on hip dual-energy x-ray absorptiometry BMD and calcium-related analytes.
Design, Setting, and Participants: The study was a 5-yr randomized, controlled, double-blind trial of 120 community-dwelling women aged 70–80 yr.
Intervention: The interventions were 1200 mg/
d calcium with placebo vitamin D (Ca group) or with 1000 IU/ d vitamin D2 (CaD group), or double placebo (control).
Main Outcome Measures: Hip BMD, plasma 25-hydroxyvitamin D, biomarkers of bone turnover, PTH, and intestinal calcium absorption were measured.
Results: Hip BMD was preserved in CaD (−0.17%) and Ca (0.19%) groups but not controls (−1.27%) at yr 1 and maintained in the CaD group only at yr 3 and 5. The beneficial effects were mainly in those with baseline 25-hydroxyvitamin D levels below the median (68 nmol/
liter). At yr 1, compared with controls, the Ca and CaD groups had 6.8 and 11.3% lower plasma alkaline phosphatase, respectively (p ≤ 0.02), and 28.7 and 34.5% lower urinary deoxypyridinoline to creatinine ratio, respectively (p ≤ 0.05). At 5 yr, this suppression was maintained only in the CaD group. CaD reduced PTH at 3 and 5 yr cf. controls (27.8 and 31.3%, p ≤ 0.005) in those with baseline PTH levels above the median (3.6 pmol/ liter). Therapy did not affect intestinal calcium absorption at high carrier loads.
Conclusions: Addition of vitamin D to calcium has long-term beneficial effects on bone density in elderly women living in a sunny climate, probably mediated by a long-term reduction in bone turnover rate.
2003-latham.pdf: “A Randomized, Controlled Trial of Quadriceps Resistance Exercise and Vitamin D in Frail Older People: The Frailty Interventions Trial in Elderly Subjects (FITNESS)”, (2003-02-20; ):
Objectives: To determine the effectiveness of vitamin D and home-based quadriceps resistance exercise on reducing falls and improving the physical health of frail older people after hospital discharge.
Design: Multicenter, randomized, controlled trial with a factorial design.
Setting: Five hospitals in Auckland, New Zealand, and Sydney, Australia.
Participants: Two hundred forty-three frail older people.
Interventions: Patients were randomized to receive a single dose of vitamin D (calciferol, 300,000 IU) or placebo tablets and 10 weeks of high-intensity home-based quadriceps resistance exercise or frequency-matched visits.
Measurements: The primary endpoints were physical health according to the short-form health survey at 3 months and falls over 6 months. Physical performance and self-rated function were secondary endpoints. Assessments took place in the participants’ homes at 3 and 6 months after randomization and were performed by blinded assessors.
Results: There was no effect of either intervention on physical health or falls, but patients in the exercise group were at increased risk of musculoskeletal injury (risk ratio = 3.6, 95% confidence interval = 1.5–8.0). Vitamin D supplementation did not improve physical performance, even in those who were vitamin D deficient (<12 ng/
mL) at baseline.
Conclusion: Neither vitamin D supplementation nor a home-based program of high-intensity quadriceps resistance exercise improved rehabilitation outcomes in frail older people after hospitalization. There was no effect of vitamin D on physical performance, and the exercises increased the risk of musculoskeletal injury. These findings do not support the routine use of these interventions at these dosages in the rehabilitation of frail older people.
Antagonistic pleiotropy, the evolutionary theory of senescence, posits that age related somatic decline is the inevitable late-life by-product of adaptations that increase fitness in early life. That concept, coupled with recent findings in oncology and gerontology, provides the foundation for an integrative theory of vertebrate senescence that reconciles aspects of the ‘accumulated damage’ ‘metabolic rate’, and ‘oxidative stress’ models. We hypothesize that (1) in vertebrates, a telomeric fail-safe inhibits tumor formation by limiting cellular proliferation. (2) The same system results in the progressive degradation of tissue function with age. (3) These patterns are manifestations of an evolved antagonistic pleiotropy in which extrinsic causes of mortality favor a species-optimal balance between tumor suppression and tissue repair. (4) With that trade-off as a fundamental constraint, selection adjusts telomere lengths—longer telomeres increasing the capacity for repair, shorter telomeres increasing tumor resistance. (5) In environments where extrinsically induced mortality is frequent, selection against senescence is comparatively weak as few individuals live long enough to suffer a substantial phenotypic decline. The weaker the selection against senescence, the further the optimal balance point moves toward shorter telomeres and increased tumor suppression. The stronger the selection against senescence, the farther the optimal balance point moves toward longer telomeres, increasing the capacity for tissue repair, slowing senescence and elevating tumor risks. (6) In iteroparous organisms selection tends to co-ordinate rates of senescence between tissues, such that no one organ generally limits life-span. A subsidiary hypothesis argues that senescent decline is the combined effect of (1) uncompensated cellular attrition and (2) increasing histological entropy. Entropy increases due to a loss of the intra-tissue positional information that normally regulates cell fate and function. Informational loss is subject to positive feedback, producing the ever-accelerating pattern of senescence characteristic of iteroparous vertebrates. Though telomere erosion begins early in development, the onset of senescence should, on average, be deferred to the species-typical age of first reproduction, the balance point at which selection on this trade-off should allow exhaustion of replicative capacity to overtake some cell lines. We observe that captive-rodent breeding protocols, designed to increase reproductive output, simultaneously exert strong selection against reproductive senescence and virtually eliminate selection that would otherwise favor tumor suppression. This appears to have greatly elongated the telomeres of laboratory mice. With their telomeric failsafe effectively disabled, these animals are unreliable models of normal senescence and tumor formation. Safety tests employing these animals likely overestimate cancer risks and underestimate tissue damage and consequent accelerated senescence.
2000-gavrilov.pdf: “Book review: _Validation of Exceptional Longevity_ by Bernard Jeune and James W. Vaupel”, Leonid A. Gavrilov, Natalia S. Gavrilova
1999-komulainen.pdf: “Prevention of Femoral and Lumbar Bone Loss with Hormone Replacement Therapy and Vitamin D3 in Early Postmenopausal Women: A Population–Based 5–Year Randomized Trial”, (1999-02-01; ):
The long term effects of hormone replacement therapy (HRT) and vitamin D3 (Vit D) on bone mineral density (BMD) were studied. A total of 464 nonosteoporotic early postmenopausal women from the Kuopio Osteoporosis Study (n = 13100) were randomized to 4 groups: (1) HRT (sequential combination of 2 mg estradiol valerate and 1 mg cyproterone acetate), (2) Vit D3 (300 and 100 IU/
day during the fifth year), (3) HRT and Vit D combined, and (4) placebo. Lumbar (L2–L4) and femoral neck BMD were determined by dual x-ray absorptiometry (DXA) at baseline and after 2.5 and 5 yr of treatment.
Intention to treat analysis (n = 464) showed that after 5 yr, lumbar BMD remained unchanged in the HRT and HRT plus Vit D groups[+ 0.2% (p = 0.658) and +0.9% (p = 0.117), respectively], whereas lumbar BMD decreased by 4.6% in the Vit D group and by 4.5% in the placebo group (p < 0.001 in both). The loss of femoral neck BMD was less in the HRT (−1.4%; p = 0.005) and HRT plus Vit D (−1.3%; p = 0.003) groups than in the Vit D and placebo groups (−4.3%; p < 0.001 in both). Among those 370 women who complied with the 5-yr treatment, the effect was more pronounced: lumbar BMD had increased by 1.5% in the HRT (p = 0.009) and by 1.8% in the HRT plus Vit D group (p = 0.005), with a plateau after 2.5 yr, whereas lumbar BMD had decreased in both the Vit D and placebo groups (4.6% and 4.7%; p < 0.001, respectively). Femoral neck BMD decreased again less in the HRT (−0.4%) and HRT plus Vit D (−0.6%) groups than in the Vit D and placebo groups (−4.4% in both).
This study confirms the positive long term effect of HRT on BMD also seen in intention to treat analysis. The data suggest that low dose vitamin D3 supplementation does not prevent bone loss in healthy, nonosteoporotic, early postmenopausal women, and it confers no benefit additional to that of HRT alone.
1990-bjorksten.pdf: “The crosslinking theory of aging—Added evidence”, (1990; ):
The cross-linking theory of aging has been gaining acceptance at a steady pace, as evidenced by many independent rediscoveries. While several earlier studies were indicative, none seemed conclusive until it was shown, using Differential Scanning Calorimetry (DSC), that protein from young human brains could be made to closely resemble protein from old brains by exposing it to either of two entirely different cross-linking agents (glutaraldehyde and dipotassium diperoxy sulfate). This work has now been repeated with additional brain material, and a statistically-more-significant number of determinations. It is now shown that a treatment of brain protein with either one or two chemically totally different compounds which have no property in common except that both are cross-linkers, changes young brain protein so that it greatly resembles old, crosslinked protein. This shows that cross-linking reactions are involved in the age related changes in the studied proteins.
[Keywords: cross-linking, aging, differential scanning calorimetry]
1986-dohm.pdf: “Metabolic responses to exercise after fasting”, (1986-10-01; ):
Fasting before exercise increases fat utilization and lowers the rate of muscle glycogen depletion. Since a 24-h fast also depletes liver glycogen, we were interested in blood glucose homeostasis during exercise after fasting. An experiment was conducted with human subjects to determine the effect of fasting on blood metabolite concentrations during exercise. Nine male subjects ran (70% maximum O2 consumption) two counterbalanced trials, once fed and once after a 23-h fast. Plasma glucose was elevated by exercise in the fasted trial but there was no difference between fed and fasted during exercise. Lactate was statistically-significantly higher (P less than 0.05) in fasted than fed throughout the exercise bout. Fat mobilization and utilization appeared to be greater in the fasted trial as evidenced by higher plasma concentrations of free fatty acids, glycerol, and beta-hydroxybutyrate as well as lower respiratory exchange ratio in the fasted trial during the first 30 min of exercise. These results demonstrate that in humans blood glucose concentration is maintained at normal levels during exercise after fasting despite the depletion of liver glycogen. Homeostasis is probably maintained as a result of increased gluconeogenesis and decreased utilization of glucose in the muscle as a result of lowered pyruvate dehydrogenase activity.
1982-bjorksten-2.pdf: “Aluminum as a Cause of Senile Dementia”, (1982-05; ):
The evidence reviewed shows that senile dementia may be similar in origin to Alzheimer’s disease and to dialysis encephalopathy. There is general agreement that aluminum, once attached to the chromatin in a neuron, cannot be dislodged by any means available to the organism. Yet the presence of aluminum in serum shows that at least some trace will always be able to pass biologic barriers and ultimately reach critical neuronal chromatin. Alfrey shows that the aluminum content of heart and brain remains relatively low until the bone content nears a saturation point, after which aluminum deposition in heart and brain accelerates (Figure 1).16 The data on aluminum content of the human aorta by Zinsser, Bjorksten, et al indicate that aluminum content peaks from age 40 to 50 years, and declines moderately thereafter.17 Thus, it is possible that persons who have the highest body level of aluminum may not survive for five years, but more data are needed to prove this theory.
1982-bjorksten.pdf: “Dietary aluminum and Alzheimer's disease”, Johan Bjorksten ( )
1981-bjorksten.pdf: “Selenium In Nutrition”, (1981-07-01; ):
Every useful substance—water, salt, air, nutrients, and vitamins as well as therapeutic agents—has a range below which it loses effectiveness and above which it becomes harmful. With selenium the optimum range is fairly narrow, and the penalties for transgression can he dramatic.
…Selenium has had dramatic acceptance in animal husbandry. However, in those countries where selenium content is minimal, the farmer who feeds his cattle selenium supplement is often himself the victim of infarctions that would have been prevented by a selenium supplement. Knowledge has gradually accumulated, and the hazards defined. Use of selenium in human nutrition and preventive medicine has become feasible.
While most of the United States has adequate selenium, some natural deficiency occurs in areas where heavy rains are common. Inclusion of selenium in dietary supplements was discussed at the U. S. Quartermaster Conference on Antioxidants in Natick, MA in 1979. A detailed specific geriatric formula in which selenium was one ingredient was published in the proceedings.15 This formula is not patented and has not been on the market, but has been used regularly by some persons for several years with apparent satisfaction.
1978-bjorksten.pdf: “A Unifying Concept for Degenerative Diseases”, John Bjorksten ( )
1977-bjorksten-2.pdf: “Pathways to the Decisive Extension of the Human Specific Lifespan”, (1977-09; ):
3 approaches to reversal or removal of gerogenic aggregations of macromolecules have shown promise. Of these the enzyme approach is the most gentle, and can be made specific. Aside from this, the lower the molecular weight of an enzyme, the better chance it will have to be immunologically tolerated as well as replicated synthetically in whole or in part. The chelating approach provides a powerful means for removing a single class of unwanted, random crosslinkages, ie., those due to extraneous polyvalent metals such as lead, cadmium and aluminum. The free hydroxyl radical approach is the most penetrant and most versatile means for removing otherwise insoluble aggregates, but its very lack of specificity will demand great foresight in control and use. Together, these three methods, when properly applied, might bring some principal objectives of gerontology within closer range.
1977-bjorksten.pdf: “Some Therapeutic Implications Of The Crosslinkage Theory Of Aging”, Johan Bjorksten ( )
1976-bjorksten.pdf: “The Crosslinkage Theory of Aging: Clinical Implications”, Johan Bjorksten ( )
1972-bjorksten.pdf: “Enzymatic Lysis in Vitro of Hyalin Deposits in Human Kidney”, (1972-05; ):
Vascular hyalin was readily dissolved in vitro from sections of the formalin-preserved, paraffin-embedded kidney of a hypertensive patient, by means of an enzyme (BJ-B-66) isolated from Bac. cereus. The enzyme attacked other hyalins and tissue components as well. The enzyme is active at body temperature and pH, and appears substantially nontoxic to rats and hamsters.
1971-bjorksten.pdf: “Gerogenic Fractions In The Tritiated Rat”, (1971-07; ):
A rat that had received tritiated acetate perinatally was killed at the age of 609 days, and was found to have retained substantial quantities of tritium in all organs examined. This study was focussed on the liver, which—after a succession of extractions with a series of various solvents followed by catalytic hydrolysis at body temperature—yielded a residue that was-insoluble in a wide range of common solubilizing media. Treatment with hot mineral acid partially dissolved this residue and electrophoretic fractionation further led to 4 fractions of which a single fraction contained most of the tritium in the insoluble residue.
Our analyses showed that the insoluble residue contained a variety of common amino acids and a considerable amount of phosphorus. The solubilized fractions derived from the insoluble residue all contained substantial concentrations of pentose, deoxypentose, and phosphorus. They showed ultraviolet absorption spectra qualitatively similar to those of nucleic acids. From their chromatographic behavior on crosslinked dextran columns, all 4 solubilized fractions showed molecular weights greater than 5000. In addition, these fractions showed substantially greater resistance to hydrolytic degradation than do authentic RNA and DNA. Taken together, this is interpreted as evidence that the gerogenic insoluble residue is composed of a highly crosslinked network of at least RNA, DNA and protein, which is stabilized by covalent cross-linkages of unusual stability. Formation of these crosslinked structures could easily interfere with the function of certain critical molecules of RNA, DNA or other polymers, leading to impaired cell function and death.
1971-bjorksten-2.pdf: “Approaches And Prospects For The Control Of Age‐Dependent Deterioration”, John Bjorksten ( )
1970-bjorksten.pdf: “Nitrogenous Compounds Immobilized In An Aged Rat”, (1970-02; ):
A pregnant rat received 8 mc of tritiated tyrosine at the time of giving birth (from seven days before, to six days after). No radioisotopes were ever given directly to the litter born. A male from this litter died from pneumonia at age 809 days. After removal of water and acetone solubles and of phospholipids, hydrolysis of the residue released the following radioactive amino acids, parts of molecules fixed until death and containing tritium present at birth: lysine, arginine, aspartic acid, glutamic acid, serine, listed in order of decreasing radioactivity, with lysine carrying 29% of the total tritium present.
1968-bjorksten.pdf: “The Crosslinkage Theory Of Aging”, (1968-04; ):
For many decades the theory and practice of cross-linking (bonding that ties two or more large molecules together side to side) have been developed in industry, but only since the 1940’s has the theory been considered in the field of medicine as a primary reaction underlying age-dependent changes.
Cross-linking is damaging to the tissues and involves loss of elasticity, reduced swelling capacity, increased resistance to hydrolases and probably enzymes generally, and thus an increase in molecular weight and a tendency toward embrittlement. There is a growing amount of direct evidence and much indirect evidence for postulating the relationship between cross-linking and aging.
Cross-linking agents present in the living organism include aldehydes, lipid oxidation products, sulfur, alkylating agents, quinones, free radicals induced by ionizing radiation, antibodies, polybasic acids, polyhalo derivatives and polyvalent metals. The latter four types of compound are slow-acting but can also accumulate in the body to form a frozen metabolic pool. Sufficient amounts of all these potential cross-linking materials are present in the body to make the changes of aging unavoidable.
1965-andrews.pdf: “The reaction of an autoxidized lipid with proteins”, (1965-09; ):
Evidence is presented which indicates that an interaction occurs between proteins and an autoxidizing unsaturated lipid. Using a model system approach, it has been established that two purified proteins (gelatin and insulin) are chemically modified in the presence of an autoxidizing lipid, methyl linoleate.
The insulin-methyl linoleate interaction has been studied chromatographically after acid and alkaline hydrolysis, and also by using the Sanger end group analysis method. The data indicate that lipid intermediates react with theε-amino group of lysine, and also with phenylalanine and glycine, the N-terminal amino groups of insulin.
Hydrogen fluoride solubility and enzyme hydrolysis determinations indicate that the autoxidation products of methyl linoleate interact with protein to produce new chemical entities through cross-linking.
1965-andrews-2.pdf: “Chemical Composition Of Enzyme-Fractionated Aged Heart Tissue”, (1965-02; ):
Fractionation of the enzyme-nonhydrolyzable constituents of human heart muscle from persons 64–74 years old resulted in separation of a fluorescing fraction, insoluble in anhydrous hydrogen fluoride, and containing 4.6% nitrogen (corresponding to 30% protein). This fraction was free from hydroxyproline and is therefore not derived from collagen.
An aromatic aldehyde was consistently separated when the enzymatically nonhydrolyzable fraction was broken down by destructive acid hydrolysis. Infrared data indicate a structure having characteristics in common with coenzyme Q.
1960-bjorksten.pdf: “Fundamentals Of Aging: A Comparison Of The Mortality Curve For Humans With A Viscosity Curve Of Gelatin During The Cross-Linking Reaction”, Johan Bjorksten, Fred Andrews ( )
1958-bjorksten.pdf: “A Common Molecular Basis For The Aging Syndrome”, (1958-10; ):
Degenerative changes must have a basic cause on the molecular level. For example, the possible role of protein immobilization by means of progressive cross-linking reactions is critically examined in the light of known data on potential cross-linking agents present in the bloodstream, and of related physio-logic facts.
1951-bjorksten.pdf: “Cross Linkages in Protein Chemistry”, (1951-01; ):
This chapter provides an overview of scattered and diverse data on the ability of proteins to form cross linkages that connect molecules or micelles, thus leading to the formation of larger aggregates. Even a single cross linkage between two large molecules has the immediate result of combining them into a unit having a molecular weight equal to the sum of the molecular weights of the molecules involved; repeated cross linkages multiply the size of molecules that are already extremely large. The immediately observable results are reduced solubility or peptizability, increased resistance to hydrothermal influences, and reduced resilience or elasticity accompanied by darkening in color, and in extreme cases, brittleness. The presence of many reactive groups in protein molecules make them particularly susceptible to cross-linking reactions. Aldehydes can form a methylene bridge, or can react with amino groups linking protein molecules together with the formation of Schiff bases. Dicarboxylic and particularly disulfonic acids can form cross-linking bridges by reaction with amino groups. The chapter briefly describes some of the principal purposes that have stimulated industrial experimentation with reactions involving cross linkage of proteins. It also outlines the types of industrial problems handled by cross-linking reactions. Further, the chapter describes cross-linking processes indicated in the literature.
1942-bjorksten.pdf: “The Chemistry of Duplication”, Johan Bjorksten ( )