Which Is the Most Significant Cause of Aging?

Linker Histones Maintain Genome Stability and Drive the Process of Cellular Ageing

Ageing comprises a cascade of processes that are inherent in all living creatures. There are fourteen general hallmarks of cellular ageing, the majority of which occur at a molecular level. A significant disturbance in the regulation of genome activity is commonly observed during cellular ageing. Overall confusion and disruption in the proper functioning of the genome are also well-known prerogatives of cancerous cells, and it is believed that this genomic instability provides a direct link between aging and cancer. The spatial organization of nuclear DNA in chromatin is the foundation of the fine-tuning and refined regulation of gene activity, and it changes during ageing. Therefore, chromatin is the platform on which genes and the environment meet and interplay. Different protein factors, small molecules and metabolites affect this chromatin organization and, through it, drive cellular deterioration and, finally, ageing. Hence, studying chromatin structural organization and dynamics is crucial for understanding life, presumably the ageing process. The complex interplay among DNA and histone proteins folds, organizes, and adapts chromatin structure. Among histone proteins, the role of the family of linker histones comes to light. Recent data point out that linker histones play a unique role in higher-order chromatin organization, which, in turn, impacts ageing to a prominent degree. Here, we discuss emerging evidence that suggests linker histones have functions that extend beyond their traditional roles in chromatin architecture, highlighting their critical involvement in genome stability, cellular ageing, and cancer development, thereby establishing them as promising targets for therapeutic interventions.

Carvacrol improved learning and memory and attenuated the brain tissue oxidative damage in aged male rats

Introduction: Aging is an unavoidable process in the body that is accompanied by impaired tissue homeostasis and various changes. Carvacrol has attracted considerable attention for its wide range of pharmacological activities. Therefore, this study attempted to explore the protective effect of carvacrol in aged rats.Materiel and methods: The aged rats were given carvacrol (15 or 30 mg/kg/day) for 4 weeks. Morris water maze and passive avoidance tests were used to determine the learning and memory abilities of the rats. The hippocampus and cortex samples were taken for biochemical analysis.Results: In comparison to young control rats, aged control rats showed learning and memory deficits. There was improvement in the Morris water navigation test and passive avoidance test performance in the treatment groups versus the aged control group. An increment in malondialdehyde (MDA) and a decrease in total thiol groups in the hippocampus and cortex samples of aged control rats in comparison to the young control group were observed. Carvacrol decreased MDA levels and increased total thiol groups in the hippocampus and cortex samples of aged rats.Conclusion: Carvacrol improved learning and memory in aged rats, probably through its anti-oxidation effects.

Extreme-aged patients (≥ 85 years) experience similar outcomes as younger geriatric patients following chronic subdural hematoma evacuation: a matched cohort study

Subdural hematoma (SDH) evacuation represents one of the most frequently performed neurosurgical procedures. Several reports cite a rise in both the age and number of patient's requiring treatment, due in part to an aging population and expanded anticoagulation use. However, limited data and conflicting conclusions exist on extreme-aged geriatric patients (≥ 85 years of age) after undergoing surgery. Patients undergoing SDH evacuation at a tertiary academic medical center between November 2013-December 2021 were retrospectively identified. The study group consisted of patients ≥ 85 years (Group 1) diagnosed with a chronic SDH surgically evacuated. A control group was created matching patients by 70-84 years of age, gender, and anticoagulation use (Group 2). Multiple metrics were evaluated between the two including length-of hospital-stay, tracheostomy/PEG placement, reoperation rate, complications, discharge location, neurological outcome at the time of discharge, and survival. A total of 130 patients were included; 65 in Group 1 and 65 in Group 2. Patient demographics, medical comorbidities, SDH characteristics, international normalized ratio, partial thromboplastin time, and use of blood thinning agents were similar between the two groups. Kaplan Meier survival analysis at one-year was 80% for Group 1 and 76% for Group 2. No significant difference was identified using the log-rank test for equality of survivor functions (p = 0.26). All measured outcomes including GCS at time of discharge, length of stay, rate of reoperations, and neurological outcome were statistically similar between the two groups. Backwards stepwise conditional logistic regression revealed no significant association between poor outcomes at the time of discharge and age. Alternatively, anticoagulation use was found to be associated with poor outcomes (OR 3.55, 95% CI 1.08-11.60; p = 0.036). Several outcome metrics and statistical analyses were used to compare patients ≥ 85 years of age to younger geriatric patients (70-84 years) in a matched cohort study. Adjusting for age group, gender, and anticoagulation use, no significant difference was found between the two groups including neurological outcome at discharge, reoperation rate, and survival.

Humanin and Its Pathophysiological Roles in Aging: A Systematic Review

BACKGROUND

Senescence is a cellular aging process in all multicellular organisms. It is characterized by a decline in cellular functions and proliferation, resulting in increased cellular damage and death. These conditions play an essential role in aging and significantly contribute to the development of age-related complications. Humanin is a mitochondrial-derived peptide (MDP), encoded by mitochondrial DNA, playing a cytoprotective role to preserve mitochondrial function and cell viability under stressful and senescence conditions. For these reasons, humanin can be exploited in strategies aiming to counteract several processes involved in aging, including cardiovascular disease, neurodegeneration, and cancer. Relevance of these conditions to aging and disease: Senescence appears to be involved in the decay in organ and tissue function, it has also been related to the development of age-related diseases, such as cardiovascular conditions, cancer, and diabetes. In particular, senescent cells produce inflammatory cytokines and other pro-inflammatory molecules that can participate to the development of such diseases. Humanin, on the other hand, seems to contrast the development of such conditions, and it is also known to play a role in these diseases by promoting the death of damaged or malfunctioning cells and contributing to the inflammation often associated with them. Both senescence and humanin-related mechanisms are complex processes that have not been fully clarified yet. Further research is needed to thoroughly understand the role of such processes in aging and disease and identify potential interventions to target them in order to prevent or treat age-related conditions.

OBJECTIVES

This systematic review aims to assess the potential mechanisms underlying the link connecting senescence, humanin, aging, and disease.

CNS Ageing in Health and Neurodegenerative Disorders

The process of ageing is characteristic of multicellular organisms associated with late stages of the lifecycle and is manifested through a plethora of phenotypes. Its underlying mechanisms are correlated with age-dependent diseases, especially neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) and multiple sclerosis (MS) that are accompanied by social and financial difficulties for patients. Over time, people not only become more prone to neurodegeneration but they also lose the ability to trigger pivotal restorative mechanisms. In this review, we attempt to present the already known molecular and cellular hallmarks that characterize ageing in association with their impact on the central nervous system (CNS)'s structure and function intensifying possible preexisting pathogenetic conditions. A thorough and elucidative study of the underlying mechanisms of ageing will be able to contribute further to the development of new therapeutic interventions to effectively treat age-dependent manifestations of neurodegenerative diseases.

Natural Deep Eutectic Extracts of Propolis, Sideritis scardica, and Plantago major Reveal Potential Antiageing Activity during Yeast Chronological Lifespan

Nowadays, the environmentally friendly approach to everyday life routines including body supplementation with pharma-, nutraceuticals and dietary supplements gains popularity. This trend is implemented in pharmaceutical as well as cosmetic and antiageing industries by adopting a newly developed green chemistry approach. Following this trend, a new type of solvents has been created, called Natural Deep Eutectic Solvents (NADES), which are produced by plant primary metabolites. These solvents are becoming a much better alternative to the already established organic solvents like ethanol and ionic liquids by being nontoxic, biodegradable, and easy to make. An interesting fact about NADES is that they enhance the biological activities of the extracted biological compounds. Here, we present our results that investigate the potential antiageing effect of CiAPD14 as a NADES solvent and three plant extracts with it. The tested NADES extracts are from propolis and two well-known medicinal plants—Sideritis scardica and Plantago major. Together with the solvent, their antiageing properties have been tested during the chronological lifespan of four Saccharomyces cerevisiae yeast strains—a wild type and three chromatin mutants. The chromatin mutants have been previously proven to exhibit characteristics of premature ageing. Our results demonstrate the potential antiageing activity of these NADES extracts, which was exhibited through their ability to confer the premature ageing phenotypes in the mutant cells by ameliorating their cellular growth and cell cycle, as well as by influencing the activity of some stress-responsive genes. Moreover, we have classified their antiageing activity concerning the strength of the observed bioactivities.

A Mechanistic Theory of Development-Aging Continuity in Humans and Other Mammals

There is consensus among biogerontologists that aging occurs either as the result of a purposeful genome-based, evolved program or due to spontaneous, randomly occurring, maladaptive events. Neither concept has yet identified a specific mechanism to explain aging’s emergence and acceleration during mid-life and beyond. Presented herein is a novel, unifying mechanism with empirical evidence that describes how aging becomes continuous with development. It assumes that aging emerges from deterioration of a regulatory process that directs morphogenesis and morphostasis. The regulatory system consists of a genome-wide “backbone” within which its specific genes are differentially expressed by the local epigenetic landscapes of cells and tissues within which they reside, thereby explaining its holistic nature. Morphostasis evolved in humans to ensure the nurturing of dependent offspring during the first decade of young adulthood when peak parental vitality prevails in the absence of aging. The strict redundancy of each morphostasis regulatory cycle requires sensitive dependence upon initial conditions to avoid initiating deterministic chaos behavior. However, when natural selection declines as midlife approaches, persistent, progressive, and specific DNA damage and misrepair changes the initial conditions of the regulatory process, thereby compromising morphostasis regulatory redundancy, instigating chaos, initiating senescence, and accelerating aging thereafter.

The intervention on aging system: A classification model, the requirement for five novel categories

Aging is widely considered an immovable fact of life. Cultural conditioning has ensured that therapeutics for extreme human lifespans are considered out of reach technologies. However, longevity therapies such as stem cell replacement, fasting, gene therapies, fasting mimetics such as metformin and rapamycin, regulation and tissue reprogramming with OSK transcription factors, blood dilution, metabolic pathway engineering, reversal of epigenetic drift, heterochronic parabiosis, coenzyme replacement technologies (nicotinamide adenine dinucleotide) and a plethora of other established sciences are showing great potential at slowing down the rate at which tissues enter dysfunction. Recent discoveries have shed light on major mysteries of the aging process. Longevity-based discoveries are not only landing quickly, but therapies to prevent or reverse those drivers of aging are also being devised regularly and this is opening up an entirely new industry, the longevity industry. This presents the requirement for a new classification system where subjects can be divided into specific groups based on their potential for mortality. This system also enables the public to target which class of this classification system they wish to be on. Moving the population on the classification system to become more disease resistant holds great benefit for society and governments as a whole.

Changes in tumor suppressors and inflammatory responses during hydrogen peroxide-induced senescence in rat fibroblasts

Cell proliferation and senescence are processes induced by oxidative stress. In this study, we aimed to establish a cellular model of rapid proliferation and senescence of rat tail-tip fibroblasts by hydrogen peroxide(H₂O₂), a well-known oxidant. On this basis, changes in oxidative stress, inflammatory response and cell cycle of fibroblasts were studied. After H₂O₂ treatment, cell counting and flow cytometry results showed that 50μM of H₂O₂ for 12h and 100μM for 8h effectively promoted fibroblast proliferation, while 500μM rapidly led to cell cycle arrest. In addition, stimulation with H₂O₂ at a concentration of 50μM also promoted the inflammatory effects of the cells. At a concentration of 100μM H₂O₂, the cellular antioxidant system began to collapse at 8h and began to affect cellular activity. 500μM of H₂O₂ at 4h the levels of senescence-associated β-galactosidase, a marker of senescence and oxidative stress, were almost positive in fibroblasts. In addition, we found that the risk of fibroblasts carcinogenesis increased with increased H₂O₂ stimulation. The results of this study indicate that H₂O₂ can cause rapid proliferation and senescence of fibroblasts and that its mechanism of action may be mainly through influencing cellular antioxidant systems, cellular inflammatory responses and cell cycle.

Genomic instability in the naturally and prematurely aged myocardium

Genomic instability, the unresolved accumulation of DNA variants, is hypothesized as one of the contributors to the natural aging process. We assessed the frequency of unresolved DNA damage reaching the transcriptome of the murine myocardium during the course of natural aging and in hearts from four distinct mouse models of premature aging with established aging-related cardiac dysfunctions. RNA sequencing and variant calling based on total RNA sequencing was compared between hearts from naturally aging mice, mice with cardiomyocyte-specific deficiency of Ercc1, a component of the DNA repair machinery, mice with reduced mitochondrial antioxidant capacity, Tert-deficient mice with reduced telomere length, and a mouse model of human Hutchinson-Gilford progeria syndrome (HGPS). Our results demonstrate that no enrichment in variants is evident in the naturally aging murine hearts until 2 y of age from the HGPS mouse model or mice with reduced telomere lengths. In contrast, a dramatic accumulation of variants was evident in Ercc1 cardiomyocyte-specific knockout mice with deficient DNA repair machinery, in mice with reduced mitochondrial antioxidant capacity, and in the intestine, liver, and lung of naturally aging mice. Our data demonstrate that genomic instability does not evidently contribute to naturally aging of the mouse heart in contrast to other organs and support the contention that the endogenous DNA repair machinery is remarkably active to maintain genomic integrity in cardiac cells throughout life.

Attenuation of protein glycation by functional polyphenolics of dragon fruit (Hylocereus polyrhizus); an in vitro and in silico evaluation

Chronic hyperglycemia and oxidative stress promote non-enzymatic glycation that leads to the production of advanced glycation end products (AGEs). AGEs casue significant damage to physiological proteins which result in several complications. The scenario also corresponds to the chronic consumption of a diet rich in AGEs. Despite understanding these mechanisms at the molecular level, the discovery of new drugs for these complications is under progress. Natural compounds might have great therapeutic potential for treating glycative consequences. In view of this, the study aimed to evaluate fruit extracts of Hylocereus polyrhizus towards determining its phenolics and flavonoid contents, as well as assessing it's in vitro antiglycative potential through the use of multistage glycation markers (early, intermediate and end stage products of β-aggregation) in sugar-protein model. In vitro hypoglycemic activity of H. polyrhizus extracts was evaluated through α-amylase and α glucosidase inhibitory activities. In vitro antioxidant potential of the fruit extracts was also examined against different free radical types including DPPH and ABTS. Among the different in vitro assays performed, methanolic and acetone extracts of the fruit, with higher phenolics and flavonoid content, have exerted significant antiglycation and antioxidant activities than other extracts namely aqueous, ethanol, hydro-ethanol, hydro-methanol, and petroleum ether. Ultra-Performance Liquid Chromatography coupled with Electrospray Ionization Mass Spectrometry (UPLC-ESI-MS/MS) analysis was employed to identify active polyphenolics that may be responsible for the antiglycative potential of H. polyrhizus. The analysis revealed some high-profile compounds that have well documented for their therapeutic benefits. Additionally, In silico analysis also showed the possible connection between identified compounds and mechanisms of action. 4- Prenylresveratrol, Vicenin, and Luteolin had observed as effectively interact with target protein in molecular docking analysis. This suggests H. polyrhizus as a good source of anti-glycation and antioxidants that may have potential applications for the treatment and prevention of glycation associated diabetic and aging complications.

Dichotomy between the transcriptomic landscape of naturally versus accelerated aged murine hearts

We investigated the transcriptomic landscape of the murine myocardium along the course of natural aging and in three distinct mouse models of premature aging with established aging-related cardiac dysfunction. Genome-wide total RNA-seq was performed and the expression patterns of protein-coding genes and non-coding RNAs were compared between hearts from naturally aging mice, mice with cardiac-specific deficiency of a component of the DNA repair machinery, mice with reduced mitochondrial antioxidant capacity and mice with reduced telomere length. Our results demonstrate that no dramatic changes are evident in the transcriptomes of naturally senescent murine hearts until two years of age, in contrast to the transcriptome of accelerated aged mice. Additionally, these mice displayed model-specific alterations of the expression levels of protein-coding and non-coding genes with hardly any overlap with age-related signatures. Our data demonstrate very limited similarities between the transcriptomes of all our murine aging models and question their reliability to study human cardiovascular senescence.

Deficits in the vesicular acetylcholine transporter alter lifespan and behavior in adult Drosophila melanogaster

The neurotransmitter acetylcholine (ACh) is involved in critical organismal functions that include locomotion and cognition. Importantly, alterations in the cholinergic system are a key underlying factor in cognitive defects associated with aging. One essential component of cholinergic synaptic transmission is the vesicular ACh transporter (VAChT), which regulates the packaging of ACh into synaptic vesicles for extracellular release. Mutations that cause a reduction in either protein level or activity lead to diminished locomotion ability whereas complete loss of function of VAChT is lethal. While much is known about the function of VAChT, the direct role of altered ACh release and its association with either an impairment or an enhancement of cognitive function are still not fully understood. We hypothesize that point mutations in Vacht cause age-related deficits in cholinergic-mediated behaviors such as locomotion, and learning and memory. Using Drosophila melanogaster as a model system, we have studied several mutations within Vacht and observed their effect on survivability and locomotive behavior. Here we report for the first time a weak hypomorphic Vacht allele that shows a differential effect on ACh-linked behaviors. We also demonstrate that partially rescued Vacht point mutations cause an allele-dependent deficit in lifespan and defects in locomotion ability. Moreover, using a thorough data analytics strategy to identify exploratory behavioral patterns, we introduce new paradigms for measuring locomotion-related activities that could not be revealed or detected by a simple measure of the average speed alone. Together, our data indicate a role for VAChT in the maintenance of longevity and locomotion abilities in Drosophila and we provide additional measurements of locomotion that can be useful in determining subtle changes in Vacht function on locomotion-related behaviors.

Metformin as Anti-Aging Therapy: Is It for Everyone?

Metformin is the most widely prescribed oral hypoglycemic medication for type 2 diabetes worldwide. Metformin also retards aging in model organisms and reduces the incidence of aging-related diseases such as neurodegenerative disease and cancer in humans. In spite of its widespread use, the mechanisms by which metformin exerts favorable effects on aging remain largely unknown. Further, not all individuals prescribed metformin derive the same benefit and some develop side effects. Before metformin finds its way to mainstay therapy for anti-aging, a more granular understanding of the effects of the drug in humans is needed. This review provides an overview of recent findings from metformin studies in aging and longevity and discusses the use of metformin to combat aging and aging-related diseases.

α-Lipoic acid prevents senescence, cell cycle arrest, and inflammatory cues in fibroblasts by inhibiting oxidative stress

Senescence is a process characterized by an irreversible growth arrest in cells and induced by oxidative stress. In the current study, anti-aging potential of a well-known antioxidant, α-lipoic acid (α-LA), in rat embryonic fibroblast (REF) cells was assessed. In this regard, oxidative stress, inflammation, and apoptosis pathways were investigated on REF cells exposed to H2O2 as a senescence inducer and α-LA as a protective compound. In cells treated with α-LA and H2O2, level of β-galactosidase, as an aging marker, and oxidative stress biomarkers, were significantly lower than those exposed to H2O2 only. Furthermore, flow cytometry assay showed that α-LA caused a significant reduction in the number of apoptotic cells via the caspase-dependent pathway. In addition, it could neutralize the inflammatory effects of H2O2 and attenuated the concentration of inflammatory cytokines. In comparison to H2O2 group, a significant increase in G0/G1 arrest was observed during cell cycle analysis in cells exposed to H2O2 and α-LA. The results of this study show that α-LA has beneficial effects on H2O2-induced cellular senescence. α-LA works by attenuating the reactive oxygen species, subsiding inflammation, and affecting cell division.

Evolution favours aging in populations with assortative mating and in sexually dimorphic populations

Since aging seems omnipresent, many authors regard it as an inevitable consequence of the laws of physics. However, recent research has conclusively shown that some organisms do not age, or at least do not age on a scale comparable with other aging organisms. This begets the question why aging evolved in some organisms yet not in others. Here we present a simulation model of competition between aging and non-aging individuals in a sexually reproducing population. We find that the aging individuals may outcompete the non-aging ones if they have a sufficiently but not excessively higher initial fecundity or if individuals mate assortatively with respect to their own phenotype. Furthermore, the aging phenotype outcompetes the non-aging one or resists dominance of the latter for a longer period in populations composed of genuine males and females compared to populations of simultaneous hermaphrodites. Finally, whereas sterilizing parasites promote non-aging, the effect of mortality-enhancing parasites is to enable longer persistence of the aging phenotype relative to when parasites are absent. Since the aging individuals replace the non-aging ones in diverse scenarios commonly found in nature, our study provides important insights into why aging has evolved in most, but not all organisms.

Molecular and biochemical evidence on the protective role of ellagic acid and silybin against oxidative stress-induced cellular aging

Aging is a natural process in living organisms that is defined by some molecular and cellular changes with time. Various causes such as mitochondrial DNA aberrations, aggregation of proteins, telomere shortening, and oxidative stress have an influential role in aging of the cells. Natural antioxidants are compounds that are potent to protect the body from detrimental effects of molecules such as free radicals. The aim of this study was to evaluate the anti-aging properties of ellagic acid (EA) and silybin (SIL), as natural antioxidant compounds on rat embryonic fibroblast (REF) cells. These cells were pre-incubated with EA and SIL, thereafter were exposed to hydrogen peroxide (H2O2). Then, the cell viability, SA-β-GAL activity, distribution of cell cycle, NF-κB, and mitochondrial complex I, II/IV enzyme activity were measured. The results of this study revealed the protective effects of EA and SIL in H2O2-treated REF cells, which confirm the previous achieved data on antioxidant and anti-inflammatory characteristics of EA and SIL against H2O2 in the treated REF cells. However, more new in vivo experiments are required to discover the anti-aging effects and mechanism of action of such compounds.

Erythropoietin suppresses D-galactose-induced aging of rats via the PI3K/Akt/Nrf2-ARE pathway

EPO (erythropoietin) is a hormone-like substance with a putative role in hematopoietic regulation. Current research suggests that it exerts a neuroprotective effect by enhancing the activity of antioxidant enzymes. Our previous studies in vitro have confirmed that EPO can delay senescence of cultured neurons by activation of nuclear factor-erythroid 2-related factor 2 (Nrf2) and the phosphoinositide-3-kinase (PI3K)/AKT pathway. Thus we set out to further substantiate the mechanism in vivo. A rat model of aging was induced by continuous subcutaneous injection of 5% D-galactose for 6 weeks. Starting at the 7th week, physiological saline or EPO was administered twice daily. LY294002, an inhibitor of the PI3K/AKT pathway, was also given to one of the groups. Improvement of learning and memory abilities were observed in the EPO intervention group. Raised levels of Cu-Zn SOD protein were detected by immunohistochemical staining and Western blot after using EPO, together with increased expression of PI3K/AKT pathway proteins. Concomitantly, there was an increase in expression of Nrf2 mRNA and a decrease in expression of Keap1 mRNA by qRT-PCR. All these effects were not found in the group injected with LY294002. We conclude that EPO can suppress aging by reducing oxidative stress. The proposed mechanism is an upregulation of the PI3K/Akt/Nrf2-ARE pathway and thus maintenance of expression and activation of antioxidant enzymes in aging rats.

Mitochondria: Central Organelles for Melatonin's Antioxidant and Anti-Aging Actions

Melatonin, along with its metabolites, have long been known to significantly reduce the oxidative stress burden of aging cells or cells exposed to toxins. Oxidative damage is a result of free radicals produced in cells, especially in mitochondria. When measured, melatonin, a potent antioxidant, was found to be in higher concentrations in mitochondria than in other organelles or subcellular locations. Recent evidence indicates that mitochondrial membranes possess transporters that aid in the rapid uptake of melatonin by these organelles against a gradient. Moreover, we predicted several years ago that, because of their origin from melatonin-producing bacteria, mitochondria likely also synthesize melatonin. Data accumulated within the last year supports this prediction. A high content of melatonin in mitochondria would be fortuitous, since these organelles produce an abundance of free radicals. Thus, melatonin is optimally positioned to scavenge the radicals and reduce the degree of oxidative damage. In light of the "free radical theory of aging", including all of its iterations, high melatonin levels in mitochondria would be expected to protect against age-related organismal decline. Also, there are many age-associated diseases that have, as a contributing factor, free radical damage. These multiple diseases may likely be deferred in their onset or progression if mitochondrial levels of melatonin can be maintained into advanced age.

Risky repair: DNA-protein crosslinks formed by mitochondrial base excision DNA repair enzymes acting on free radical lesions

Oxygen is both necessary and dangerous for aerobic cell function. ATP is most efficiently made by the electron transport chain, which requires oxygen as an electron acceptor. However, the presence of oxygen, and to some extent the respiratory chain itself, poses a danger to cellular components. Mitochondria, the sites of oxidative phosphorylation, have defense and repair pathways to cope with oxidative damage. For mitochondrial DNA, an essential pathway is base excision repair, which acts on a variety of small lesions. There are instances, however, in which attempted DNA repair results in more damage, such as the formation of a DNA-protein crosslink trapping the repair enzyme on the DNA. That is the case for mitochondrial DNA polymerase γ acting on abasic sites oxidized at the 1-carbon of 2-deoxyribose. Such DNA-protein crosslinks presumably must be removed in order to restore function. In nuclear DNA, ubiquitylation of the crosslinked protein and digestion by the proteasome are essential first processing steps. How and whether such mechanisms operate on DNA-protein crosslinks in mitochondria remains to be seen.

The Anti-Aging Effect of Erythropoietin via the ERK/Nrf2-ARE Pathway in Aging Rats

Erythropoietin (EPO) has a neuroprotective effect and can resist aging, which most likely occur through EPO increasing the activity of antioxidant enzymes and scavenging free radicals. In this study, we verified the anti-aging function of EPO and discussed the mechanism occurring through the extracellular signal-regulated kinase (ERK)/NF-E2-related factor 2 (Nrf2)-ARE pathway. A rat model of aging was induced by the continuous subcutaneous injection of 5 % D-galactose for 6 weeks. At the beginning of the sixth week, physiological saline or EPO was administered twice per day through a lateral ventricle system for a total of 7 days. In one group, 2 μl PD98059 was administered 30 min before EPO. Learning and memory ability were analyzed with the Morris water maze system. HE staining was used to observe the morphological changes in the neurons in the hippocampus, and immunohistochemical staining as well as Western blots were carried out to detect the expression of ERK for each group of rats and the expression of phosphorylated-ERK (P-ERK), Nrf2, and superoxide dismutase (SOD). Real-Time PCR was carried out to detect the amount of Nrf2 mRNA and the KEAP1 mRNA expression. EPO can significantly improve learning and memory ability in aging rats and can provide protection against aging by improving the hippocampus morphology. Immunohistochemical staining and Western blots showed P-ERK, Nrf2, and Cu-Zn SOD decreases in aging rats compared to the normal group, while the expression for those proteins increased after EPO intervention. PD98059 inhibited the enhanced expression of P-ERK, Nrf2, and Cu-Zn SOD induced by EPO. Real-Time PCR results suggested that the trend of Nrf2mRNA expression was the same as that for the proteins, which confirmed that the enhancement occurred at the gene level. As such, EPO can significantly resist or delay aging and protect the brain by reducing oxidative stress. The most likely mechanism is that EPO can promote the ERK/Nrf2-ARE pathway in aging rats and that PD98059 can inhibit that process. These findings may facilitate further studies on the mechanism of aging and applications for the neuroprotective properties of EPO for clinical treatments.

Oxidative stress and frailty: A systematic review and synthesis of the best evidence

OBJECTIVE

Oxidative stress (OS) is associated with accelerated aging. Previous studies have suggested a possible relationship between OS and frailty but this association remains unclear. We conducted a systematic review to investigate potential interactions between OS and frailty.

METHODS

A systematic literature search of original reports providing data on 'OS and antioxidant' parameters and frailty was carried out across major electronic databases from inception until May 2016. Cross-sectional/case control and longitudinal studies reporting data on the association between frailty and anti-oxidants-OS biomarkers were considered for inclusion. Results were summarized with a synthesis based on the best evidence.

RESULTS

From 1856 hits, 8 studies (cross-sectional/case control) were included (N=6349; mean age of 75±12years; 56.4% females). Overall, there were 588 (=9.3%) frail, 3036 pre-frail (=47.8%), 40 (=0.6%) pre-frail/robust, and 2685 (=42.3%) robust subjects. Six cross-sectional/case control studies demonstrated that frailty was associated with an increase in peripheral OS biomarkers, including lipoprotein phospholipase A2 (1 study), isoprostanes (2 studies), malonaldehyde (2 studies), 8-hydroxy-20-deoxyguanosine (2 studies), derivate of reactive oxygen metabolites (2 studies), oxidized glutathione/glutathione (1 study), 4-hydroxy-2,3-nonenal (1 study), and protein carbonylation levels (1 study). In addition, preliminary evidence points to lower anti-oxidant parameters (vitamin C, E, α-tocopherol, biological anti-oxidant potential, total thiol levels) in frailty.

CONCLUSION

Frailty and pre-frailty appear to be associated with higher OS and possibly lower anti-oxidant parameters. However, due to the cross-sectional design, it is not possible to disentangle the directionality of the relationships observed. Thus, future high-quality and in particular longitudinal research is required to confirm or refute these relationships and to further elucidate pathophysiological mechanisms.

Astaxanthin in cardiovascular health and disease: mechanisms of action, therapeutic merits, and knowledge gaps

Cardiovascular disease is the main contributor to morbidity and mortality worldwide.

In vitro cytotoxicity, genotoxicity and antigenotoxicity assessment of Solanum lycocarpum hydroalcoholic extract

CONTEXT

Solanum lycocarpum A. St.-Hil. (Solanaceae), popularly known as 'fruta-do-lobo' (wolf fruit), 'lobeira' and 'jurubebão', is commonly used by native people of Central Brazil in powder form or as a hydroalcoholic extract for the management of diabetes and obesity and to decrease cholesterol levels.

OBJECTIVE

The present study determines the possible cytotoxic, genotoxic and antigenotoxic activities of hydroalcoholic extract of the S. lycocarpum fruits (SL).

MATERIALS AND METHODS

The clonogenic efficiency assay was used to determine the cytotoxicity. Three concentrations of SL (16, 32 and 64 μg/mL) were used for the evaluation of its genotoxic and antigenotoxic potential on V79 cells using the micronucleus and comet assays. In the antigenotoxicity assays, the cells were treated simultaneously with SL and the alkylating agent methyl methanesulphonate (MMS, 44 μg/mL for the micronucleus assay and 22 μg/mL for the comet assay) as an inducer of micronuclei and DNA damage.

RESULTS

The results showed that SL was cytotoxic at concentrations up to 64 μg/mL. No significant differences in the rate of chromosome or DNA damage were observed between cultures treated with SL and the control group. In addition, the frequencies of micronuclei and DNA damage induced by MMS were significantly reduced after treatment with SL. The damage reduction percentage ranged from 68.1% to 79.2% and 12.1% to 16.5% for micronucleus and comet assays, respectively.

DISCUSSION AND CONCLUSION

SL exerted no genotoxic effect and exhibited chemopreventive activity against both genomic and chromosome damage induced by MMS.