Lack of robustness of life extension associated with several single-gene P element mutations in Drosophila melanogaster

The hypothesis tested in this study was that single-gene mutations found previously to extend the life span of Drosophila melanogaster could do so consistently in both long-lived y w and standard w (1118) genetic backgrounds. GAL4 drivers were used to express upstream activation sequence (UAS)-responder transgenes globally or in the nervous system. Transgenes associated with oxidative damage prevention (UAS-hSOD1 and UAS-GCLc) or removal (EP-UAS-Atg8a and UAS-dTOR (FRB) ) failed to increase mean life spans in any expression pattern in either genetic background. Flies containing a UAS-EGFP-bMSRA (C) transgene associated with protein repair were found not to exhibit life extension or detectable enhanced green fluorescent protein (EGFP) activity. The presence of UAS-responder transgenes was confirmed by PCR amplification and sequencing at the 5' and 3' end of each insertion. These results cast doubt on the robustness of life extension in flies carrying single-gene mutations and suggest that the effects of all such mutations should be tested independently in multiple genetic backgrounds and laboratory environments.

Decreased levels of proapoptotic factors and increased key regulators of mitochondrial biogenesis constitute new potential beneficial features of long-lived growth hormone receptor gene-disrupted mice

Decreased somatotrophic signaling is among the most important mechanisms associated with extended longevity. Mice homozygous for the targeted disruption of the growth hormone (GH) receptor gene (GH receptor knockout; GHRKO) are obese and dwarf, are characterized by a reduced weight and body size, undetectable levels of GH receptor, high concentration of serum GH, and greatly reduced plasma levels of insulin and insulin-like growth factor-I, and are remarkably long lived. Recent results suggest new features of GHRKO mice that may positively affect longevity-decreased levels of proapoptotic factors and increased levels of key regulators of mitochondrial biogenesis. The alterations in levels of the proapoptotic factors and key regulators of mitochondrial biogenesis were not further improved by two other potential life-extending interventions-calorie restriction and visceral fat removal. This may attribute the primary role to GH resistance in the regulation of apoptosis and mitochondrial biogenesis in GHRKO mice in terms of increased life span.

Age validation in the long life family study through a linkage to early-life census records

OBJECTIVES

Studies of health and longevity require accurate age reporting. Age misreporting among older adults in the United States is common.

METHODS

Participants in the Long Life Family Study (LLFS) were matched to early-life census records. Age recorded in the census was used to evaluate age reporting in the LLFS. The study population was 99% non-Hispanic white.

RESULTS

About 88% of the participants were matched to 1910, 1920, or 1930 U.S. censuses. Match success depended on the participant's education, place of birth, and the number of censuses available to be searched. Age at the time of the interview based on the reported date of birth and early-life census age were consistent for about 89% of the participants, and age consistency within 1 year was found for about 99% of the participants.

DISCUSSION

It is possible to match a high fraction of older study participants to their early-life census records when detailed information is available on participants' family of origin. Such record linkage can provide an important source of information for evaluating age reporting among the oldest old participants. Our results are consistent with recent studies suggesting that age reporting among older whites in the United States appears to be quite good.

Systems biology in aging: linking the old and the young

Aging can be defined as a process of progressive decline in the physiological capacity of an organism, manifested by accumulated alteration and destabilization at the whole system level. Systems biology approaches offer a promising new perspective to examine the old problem of aging. We begin this review by introducing the concepts of systems biology, and then illustrate the application of systems biology approaches to aging research, from gene expression profiling to network analysis. We then introduce the network that can be constructed using known lifespan and aging regulators, and conclude with a look forward to the future of systems biology in aging research. In summary, systems biology is not only a young field that may help us understand aging at a higher level, but also an important platform that can link different levels of knowledge on aging, moving us closer to a more comprehensive control of systematic decline during aging.

Evidence of a triosephosphate isomerase non-catalytic function crucial to behavior and longevity

Triosephosphate isomerase (TPI) is a glycolytic enzyme that converts dihydroxyacetone phosphate (DHAP) into glyceraldehyde 3-phosphate (GAP). Glycolytic enzyme dysfunction leads to metabolic diseases collectively known as glycolytic enzymopathies. Of these enzymopathies, TPI deficiency is unique in the severity of neurological symptoms. The Drosophila sugarkill mutant closely models TPI deficiency and encodes a protein prematurely degraded by the proteasome. This led us to question whether enzyme catalytic activity was crucial to the pathogenesis of TPI sugarkill neurological phenotypes. To study TPI deficiency in vivo we developed a genomic engineering system for the TPI locus that enables the efficient generation of novel TPI genetic variants. Using this system we demonstrate that TPI sugarkill can be genetically complemented by TPI encoding a catalytically inactive enzyme. Furthermore, our results demonstrate a non-metabolic function for TPI, the loss of which contributes significantly to the neurological dysfunction in this animal model.

Chromatin remodeling, DNA damage repair and aging

Cells are constantly exposed to a variety of environmental and endogenous conditions causing DNA damage, which is detected and repaired by conserved DNA repair pathways to maintain genomic integrity. Chromatin remodeling is critical in this process, as the organization of eukaryotic DNA into compact chromatin presents a natural barrier to all DNA-related events. Studies on human premature aging syndromes together with normal aging have suggested that accumulated damages might lead to exhaustion of resources that are required for physiological functions and thus accelerate aging. In this manuscript, combining the present understandings and latest findings, we focus mainly on discussing the role of chromatin remodeling in the repair of DNA double-strand breaks (DSBs) and regulation of aging.

Genome-Wide RNAi Longevity Screens in Caenorhabditis elegans

Progress in aging research has identified genetic and environmental factors that regulate longevity across species. The nematode worm Caenorhabditiselegans is a genetically tractable model system that has been widely used to investigate the molecular mechanisms of aging, and the development of RNA interference (RNAi) technology has provided a powerful tool for performing large-scale genetic screens in this organism. Genome-wide screens have identified hundreds of genes that influence lifespan, many of which fall into distinct functional classes and pathways. The purpose of this review is to summarize the results of large-scale RNAi longevity screens in C. elegans, and to provide an in-depth comparison and analysis of their methodology and most significant findings.

MicroRNA in Aging: From Discovery to Biology

MicroRNAs (miRNAs) are small non-coding RNA molecules that negatively regulate gene expression of their targets at the post-transcriptional levels. A single miRNA can target up to several hundred mRNAs, thus capable of significantly altering gene expression regulatory networks. In-depth study and characterization of miRNAs has elucidated their critical functions in development, homeostasis, and disease. A link between miRNAs and longevity has been demonstrated in C. elegans, implicating their role in regulation of lifespan and in the aging process. Recent years have witnessed unprecedented technological advances in studies of miRNAs, including ultra-high throughput sequencing technologies that allow comprehensive discovery of miRNAs and their targets. Here we review the latest experimental approaches from the perspective of understanding miRNA gene expression regulatory networks in aging. We provide a methodological work flow that can be employed to discover aging-related miRNAs and their targets, and to functionally validate their roles in aging. Finally, we review the links between miRNAs known to act in the conserved pathways of aging and major aging-related diseases. Taken together, we hope to provide a focused review to facilitate future endeavor of uncovering the functional role of miRNA in aging.

The rise and fall of women's advantage: a comparison of national trends in life expectancy at age 65 years

The female advantage in life expectancy (LE) is found worldwide, despite differences in living conditions, the status of women and other factors. However, this advantage has decreased in recent years in low-mortality countries. Few researchers have looked at the gender gap in LE in old age (age 65) in a longer historical perspective. Have women always had an advantage in LE at old age and do different countries share the same trends? Life expectancy data for 17 countries were assessed from Human Mortality Database from 1751 to 2007. Since most of the changes in LE taking place today are driven by reductions of old age mortality the gender difference in LE was calculated at age 65. Most low-mortality countries show the same historical trend, a rise and fall of women’s advantage in LE at age 65. Three phases that all but two countries passed through were discerned. After a long phase with a female advantage in LE at 65 of <1 year, the gender gap increased significantly during the twentieth century. The increase occurred in all countries but at different time points. Some countries such as England and France had an early rise in female advantage (1900–1919), while it occurred 50 years later in Sweden, Norway and in the Netherlands. The rise was followed by a more simultaneous fall in female advantage in the studied countries towards the end of the century, with exceptions of Japan and Spain. The different timing regarding the increase of women’s advantage indicates that country-specific factors may have driven the rise in female advantage, while factors shared by all countries may underlie the simultaneous fall. More comprehensive, multi-disciplinary study of the evolution of the gender gap in old age could provide new hypotheses concerning the determinants of gendered differences in mortality.

The effect of clinical performance on the survival estimates of direct restorations

Objectives

In most retrospective studies, the clinical performance of restorations had not been considered in survival analysis. This study investigated the effect of including the clinically unacceptable cases according to modified United States Public Health Service (USPHS) criteria into the failed data on the survival analysis of direct restorations as to the longevity and prognostic variables.

Materials and Methods

Nine hundred and sixty-seven direct restorations were evaluated. The data of 204 retreated restorations were collected from the records, and clinical performance of 763 restorations in function was evaluated according to modified USPHS criteria by two observers. The longevity and prognostic variables of the restorations were compared with a factor of involving clinically unacceptable cases into the failures using Kaplan-Meier survival analysis and Cox proportional hazard model.

Results

The median survival times of amalgam, composite resin and glass ionomer were 11.8, 11.0 and 6.8 years, respectively. Glass ionomer showed significantly lower longevity than composite resin and amalgam. When clinically unacceptable restorations were included into the failure, the median survival times of them decreased to 8.9, 9.7 and 6.4 years, respectively.

Conclusions

After considering the clinical performance, composite resin was the only material that showed a difference in the longevity (p < 0.05) and the significantly higher relative risk of student group than professor group disappeared in operator groups. Even in the design of retrospective study, clinical evaluation needs to be included.

Personality profile of the children of long-lived parents

OBJECTIVES

Past research has shown that parental longevity is related to offspring physical health and longevity. Preliminary studies suggest that parental longevity may be linked to the offspring's personality traits. A comprehensive 5-factor personality model has been related to physical health, but the association with parental longevity has not yet been investigated. We used a 5-factor personality model to investigate the relationship between parental longevity and offspring personality.

METHOD

Data from the longitudinal Health and Retirement Study (HRS) was used in the analyses. Using the Midlife Development Inventory and the Life Orientation test, the relationship between parental attained age and offspring personality was assessed using regression models for both men and women.

RESULTS

Male offspring of long-lived fathers and mothers were more likely to be open to new experiences (p < .01) and be more extroverted (p = .03) compared with male offspring of short-lived fathers or mothers. Maternal or paternal attained age had no effect on the female offspring personality traits.

DISCUSSION

Personality is an important phenotype to consider when investigating genetic and environmental determinants of longevity. Further research is needed to investigate the potential of gender-specific mechanisms.

Caenorhabditis elegans ATR checkpoint kinase ATL-1 influences life span through mitochondrial maintenance

ATR is highly conserved in all eukaryotes and functions as a cell-cycle nuclear checkpoint kinase. In mammals, ATR is essential whose complete absence results in early embryonic lethality and its hypomorphic mutation causes a complex disease known as Seckel syndrome. However, molecular mechanisms that cause a wide variety of symptoms including accelerated aging have remained unclear. Similarly, in the nematode Caenorhabditis elegans, a deletion mutant of ATR ortholog atl-1 appears to develop into normal adults, but their eggs do not hatch and die at early embryogenesis. Here we show that the parental worms of atl-1 defective mutant achieved longevity. Transcription levels of certain superoxide dismutase genes, sod-3 and -5 and enzymatic activity of superoxide dismutases significantly increased in the mutant. Furthermore, lipid peroxidation such as a formation of malondialdehyde was attenuated. Expressions of other genes regulated by DAF-16/FOXO transcription factor were also altered. In contrast, the mutant became hypersensitive to rotenone and ethidium bromide. Compared with the wild type the mitochondrial DNA copy number in the mutant was lesser and its proliferation is more severely inhibited in the presence of rotenone. These results suggest that C. elegans ATL-1 is involved not only in the nuclear checkpoint control but also in the mitochondrial maintenance, and its dysfunction activates mild oxidative stress response, resulting in an alteration of life span.

Life-span extension from hypoxia in Caenorhabditis elegans requires both HIF-1 and DAF-16 and is antagonized by SKN-1

Stabilization of the hypoxia-inducible factor (HIF-1) protein extends longevity in Caenorhabditis elegans. However, stabilization of mammalian HIF-1α has been implicated in tumor growth and cancer development. Consequently, for the hypoxic response to benefit mammalian health, we must determine the components of the response that contribute to longevity, and separate them from those that cause harm in mammals. Here, we subject adult worms to low oxygen environments. We find that growth in hypoxia increases longevity in wild-type worms but not in animals lacking HIF-1 or DAF-16. Conversely, hypoxia shortens life span in combination with overexpression of the antioxidant stress response protein SKN-1. When combined with mutations in other longevity pathways or dietary restriction, hypoxia extends life span but to varying extents. Collectively, our results show that hypoxia modulates longevity in a complex manner, likely involving components in addition to HIF-1.

High carbohydrate-low protein consumption maximizes Drosophila lifespan

Dietary restriction extends lifespan in a variety of organisms, but the key nutritional components driving this process and how they interact remain uncertain. In Drosophila, while a substantial body of research suggests that protein is the major dietary component affecting longevity, recent studies claim that carbohydrates also play a central role. To clarify how nutritional factors influence longevity, nutrient consumption and lifespan were measured on a series of diets with varying yeast and sugar content. We show that optimal lifespan requires both high carbohydrate and low protein consumption, but neither nutrient by itself entirely predicts lifespan. Increased dietary carbohydrate or protein concentration does not always result in reduced feeding-the regulation of food consumption is best described by a constant daily caloric intake target. Moreover, due to differences in food intake, increased concentration of a nutrient within the diet does not necessarily result in increased consumption of that particular nutrient. Our results shed light on the issue of dietary effects on lifespan and highlight the need for accurate measures of nutrient intake in dietary manipulation studies.

Personality factors in the Long Life Family Study

OBJECTIVES

To evaluate personality profiles of Long Life Family Study participants relative to population norms and offspring of centenarians from the New England Centenarian Study. METHOD Personality domains of agreeableness, conscientiousness, extraversion, neuroticism, and openness were assessed with the NEO Five-Factor Inventory in 4,937 participants from the Long Life Family Study (mean age 70 years). A linear mixed model of age and gender was implemented adjusting for other covariates.

RESULTS

A significant age trend was found in all five personality domains. On average, the offspring generation of long-lived families scored low in neuroticism, high in extraversion, and within average values for the other three domains. Older participants tended to score higher in neuroticism and lower in the other domains compared with younger participants, but the estimated scores generally remained within average population values. No significant differences were found between long-lived family members and their spouses.

DISCUSSION

Personality factors and more specifically low neuroticism and high extraversion may be important for achieving extreme old age. In addition, personality scores of family members were not significantly different from those of their spouses, suggesting that environmental factors may play a significant role in addition to genetic factors.

Smoking mediates the effect of conscientiousness on mortality: The Veterans Affairs Normative Aging Study

This study examined the relationship between conscientiousness and mortality over 18 years and whether smoking behavior mediated this relationship. We utilized data from the Veterans Affairs Normative Aging Study on 1349 men who completed the Goldberg (1992) adjectival markers of the Big Five. Over the 18-year follow-up, 547 (41%) participants died. Through proportional hazards modeling in a structural equation modeling framework, we found that higher levels of conscientiousness significantly predicted longer life, and that this effect was mediated by current smoking status at baseline. Methodologically, we also demonstrate the effectiveness of using a structural equation modeling framework to evaluate mediation when using a censored outcome such as mortality.

Caffeine extends life span, improves healthspan, and delays age-associated pathology in Caenorhabditis elegans

BACKGROUND

The longevity of an organism is influenced by both genetic and environmental factors. With respect to genetic factors, a significant effort is being made to identify pharmacological agents that extend life span by targeting pathways with a defined role in the aging process. On the environmental side, the molecular mechanisms responsible for the positive influence of interventions such as dietary restriction are being explored. The environment experienced by humans in modern societies already contains countless compounds that may influence longevity. Understanding the role played by common compounds that substantially affect the aging process will be critical for predicting and interpreting the outcome of introducing new interventions. Caffeine is the most widely used psychoactive drug worldwide. Prior studies in flies, worms, and mice indicate that caffeine may positively impact age-associated neurodegenerative pathology, such as that observed in Alzheimer's disease.

RESULTS

Here we report that caffeine is capable of extending life span and improving healthspan in Caenorhabditis elegans, a finding that is in agreement with a recently published screen looking for FDA-approved compounds capable of extending worm life span. Life span extension using caffeine displays epistatic interaction with two known longevity interventions: dietary restriction and reduced insulin signaling. Caffeine treatment also delays pathology in a nematode model of polyglutamine disease.

CONCLUSIONS

The identification of caffeine as a relevant factor in aging and healthspan in worms, combined with prior work in both humans and rodents linking caffeine consumption to reduced risk of age-associated disease, suggests that caffeine may target conserved longevity pathways. Further, it may be important to consider caffeine consumption when developing clinical interventions, particularly those designed to mimic dietary restriction or modulate insulin/IGF-1-like signaling. The positive impact of caffeine on a worm model of polyglutamine disease suggests that chronic caffeine consumption may generally enhance resistance to proteotoxic stress and may be relevant to assessing risk and developing treatments for human diseases like Alzheimer's and Huntington's disease. Future work addressing the relevant targets of caffeine in models of aging and healthspan will help to clarify the underlying mechanisms and potentially identify new molecular targets for disease intervention.

Interspecies Chemical Signals Released into the Environment May Create Xenohormetic, Hormetic and Cytostatic Selective Forces that Drive the Ecosystemic Evolution of Longevity Regulation Mechanisms

Various organisms (i.e., bacteria, fungi, plants and animals) within an ecosystem can synthesize and release into the environment certain longevity-extending small molecules. Here we hypothesize that these interspecies chemical signals can create xenohormetic, hormetic and cytostatic selective forces driving the ecosystemic evolution of longevity regulation mechanisms. In our hypothesis, following their release into the environment by one species of the organisms composing an ecosystem, such small molecules can activate anti-aging processes and/or inhibit pro-aging processes in other species within the ecosystem. The organisms that possess the most effective (as compared to their counterparts of the same species) mechanisms for sensing the chemical signals produced and released by other species and for responding to such signals by undergoing certain hormetic and/or cytostatic life-extending changes to their metabolism and physiology are expected to live longer then their counterparts within the ecosystem. Thus, the ability of a species of the organisms composing an ecosystem to undergo life-extending metabolic or physiological changes in response to hormetic or cytostatic chemical compounds released to the ecosystem by other species: 1) increases its chances of survival; 2) creates selective forces aimed at maintaining such ability; and 3) enables the evolution of longevity regulation mechanisms.

Aging genetics and aging

The process of aging refers to the decay of an organism's structure and function, in which molecular and cellular modifications can have various effects at the individual level over the course of a lifetime. The accumulation of molecular errors that compromise adult stem cell functions occurs because of genetic and epigenetic interactions and depends on hereditary, environmental, and stochastic factors. Here we review the known genetic factors involved in aging.

Modern Medicine: Towards Prevention, Cure, Well-being and Longevity

Modern medicine has done much in the fields of infectious diseases and emergencies to aid cure. In most other fields, it is mostly control that it aims for, which is another name for palliation. Pharmacology, psychopharmacology included, is mostly directed towards such control and palliation too. The thrust, both of clinicians and research, must now turn decisively towards prevention and cure. Also, longevity with well-being is modern medicine's other big challenge. Advances in vaccines for hypertension, diabetes, cancers etc, deserve attention; as also, the role of meditation, yoga, spirituality etc in preventing disease at various levels. Studies on longevity, life style changes and healthy centenarians deserve special scrutiny to find what aids longevity with wellbeing. A close look at complementary and alternative medicine is needed to find any suitable models they may have, cutting aside their big talk and/or hostility towards mainstream medical care. Medicine is a manifestation of the human eros, and should not become a means of its thanatos. It must realise its true potential, so that eros prevails, and thanatos prevails only ultimately, not prematurely.

Longevity nutrients resveratrol, wines and grapes

A mild-to-moderate wine drinking has been linked with reduced cardiovascular, cerebrovascular, and peripheral vascular risk as well as reduced risk due to cancer. The reduced risk of cardiovascular disease associated with wine drinking is popularly known as French Paradox. A large number of reports exist in the literature indicating that resveratrol present in wine is primarily responsible for the cardioprotection associated with wine. Recently, resveratrol was shown to extend life span in yeast through the activation of longevity gene SirT1, which is also responsible for the longevity mediated by calorie restriction. This review summarizes the reports available on the functional and molecular biological aspects of resveratrol, wine and grapes in potentiating the longevity genes.

Diseases of poverty and lifestyle, well-being and human development

The problems of the haves differ substantially from those of the have-nots. Individuals in developing societies have to fight mainly against infectious and communicable diseases, while in the developed world the battles are mainly against lifestyle diseases. Yet, at a very fundamental level, the problems are the same-the fight is against distress, disability, and premature death; against human exploitation and for human development and self-actualisation; against the callousness to critical concerns in regimes and scientific power centres.While there has been great progress in the treatment of individual diseases, human pathology continues to increase. Sicknesses are not decreasing in number, they are only changing in type.The primary diseases of poverty like TB, malaria, and HIV/AIDS-and the often co-morbid and ubiquitous malnutrition-take their toll on helpless populations in developing countries. Poverty is not just income deprivation but capability deprivation and optimism deprivation as well.While life expectancy may have increased in the haves, and infant and maternal mortality reduced, these gains have not necessarily ensured that well-being results. There are ever-multiplying numbers of individuals whose well-being is compromised due to lifestyle diseases. These diseases are the result of faulty lifestyles and the consequent crippling stress. But it serves no one's purpose to understand them as such. So, the prescription pad continues to prevail over lifestyle-change counselling or research.The struggle to achieve well-being and positive health, to ensure longevity, to combat lifestyle stress and professional burnout, and to reduce psychosomatic ailments continues unabated, with hardly an end in sight.WE THUS REALISE THAT MORBIDITY, DISABILITY, AND DEATH ASSAIL ALL THREE SOCIETIES: the ones with infectious diseases, the ones with diseases of poverty, and the ones with lifestyle diseases. If it is bacteria in their various forms that are the culprit in infectious diseases, it is poverty/deprivation in its various manifestations that is the culprit in poverty-related diseases, and it is lifestyle stress in its various avatars that is the culprit in lifestyle diseases. It is as though poverty and lifestyle stress have become the modern "bacteria" of developing and developed societies, respectively.For those societies afflicted with diseases of poverty, of course, the prime concern is to escape from the deadly grip of poverty-disease-deprivation-helplessness; but, while so doing, they must be careful not to land in the lap of lifestyle diseases. For the haves, the need is to seek well-being, positive health, and inner rootedness; to ask science not only to give them new pills for new ills, but to define and study how negative emotions hamper health and how positive ones promote it; to find out what is inner peace, what is the connection between spirituality and health, what is well-being, what is self-actualisation, what prevents disease, what leads to longevity, how simplicity impacts health, what attitudes help cope with chronic sicknesses, how sicknesses can be reversed (not just treated), etc. Studies on well-being, longevity, and simplicity need the concerted attention of researchers.THE TASK AHEAD IS CUT OUT FOR EACH ONE OF US: physician, patient, caregiver, biomedical researcher, writer/journalist, science administrator, policy maker, ethicist, man of religion, practitioner of alternate/complementary medicine, citizen of a world community, etc. Each one must do his or her bit to ensure freedom from disease and achieve well-being.Those in the developed world have the means to make life meaningful but, often, have lost the meaning of life itself; those in the developing world are fighting for survival but, often, have recipes to make life meaningful. This is especially true of a society like India, which is rapidly emerging from its underdeveloped status. It is an ancient civilization, with a philosophical outlook based on a robust mix of the temporal and the spiritual, with vibrant indigenous biomedical and related disciplines, for example, Ayurveda, Yoga, etc. It also has a burgeoning corpus of modern biomedical knowledge in active conversation with the rest of the world. It should be especially careful that, while it does not negate the fruits of economic development and scientific/biomedical advance that seem to beckon it in this century, it does not also forget the values that have added meaning and purpose to life; values that the ancients bequeathed it, drawn from their experiential knowledge down the centuries.The means that the developed have could combine with the recipes to make them meaningful that the developing have. That is the challenge ahead for mankind as it gropes its way out of poverty, disease, despair, alienation, anomie, and the ubiquitous all-devouring lifestyle stresses, and takes halting steps towards well-being and the glory of human development.

The hormetic effects of hypergravity on longevity and aging

This paper reviews the literature on the effects of hypergravity (HG, gravity levels higher than 1g, the terrestrial gravity) on longevity and aging. The different studies showed that life-long exposures to high gravity levels decreased longevity and accelerated the age-related decline observed on some physiological and behavioral variables. In contrast, chronic exposure to HG increased resistance to heat in young and middle-aged Drosophila melanogaster. A short exposure to HG at the beginning of adult life increased male longevity and delayed behavioral aging in D. melanogaster. All these results show that HG acts as a hormetic factor. Long exposures to HG have deleterious effects on longevity and aging, whereas short exposures have beneficial effects. Some potential mechanisms of action of the beneficial effects of HG are also reviewed here. However, the ones tested so far (heat shock proteins and antioxidant defense) have proven unable to explain the hormetic effects of HG and their mechanisms of action are still unknown.

Three layer functional model and energy exchange concept of aging process

Relying on a certain degree of abstraction, we can propose that no particular distinction exists between animate or living matter and inanimate matter. While focusing attention on some specifics, the dividing line between the two can be drawn. The most apparent distinction is in the level of structural and functional organization with the dissimilar streams of 'energy flow' between the observed entity and the surrounding environment. In essence, living matter is created from inanimate matter which is organized to contain internal intense energy processes and maintain lower intensity energy exchange processes with the environment. Taking internal and external energy processes into account, we contend in this paper that living matter can be referred to as matter of dissipative structure, with this structure assumed to be a common quality of all living creatures and living matter in general. Interruption of internal energy conversion processes and terminating the controlled energy exchange with the environment leads to degeneration of dissipative structure and reduction of the same to inanimate matter, (gas, liquid and/or solid inanimate substances), and ultimately what can be called 'death.' This concept of what we call dissipative nature can be extended from living organisms to social groups of animals, to mankind. An analogy based on the organization of matter provides a basis for a functional model of living entities. The models relies on the parallels among the three central structures of any cell (nucleus, cytoplasm and outer membrane) and the human body (central organs, body fluids along with the connective tissues, and external skin integument). This three-part structural organization may be observed almost universally in nature. It can be observed from the atomic structure to the planetary and intergalactic organizations. This similarity is corroborated by the membrane theory applied to living organisms. According to the energy nature of living matter and the proposed functional model, the decreased integrity of a human body's external envelope membrane is a first cause of the structural degradation and aging of the entire organism. The aging process than progresses externally to internally, as in single cell organisms, suggesting that much of the efforts towards the restoration and maintenance of the mechanisms responsible for structural development should be focused accordingly, on the membrane, i.e., the skin. Numerous reports indicate that all parts of the human body, like: bones, blood with blood vessels, muscles, skin, and so on, have some ability for restoration. Therefore, actual revival of not only aging tissue of the human body's membrane, but the entire human body enclosed within, with all internal organs, might be expected. We assess several aging theories within the context of our model and provide suggestions on how to activate the body's own anti-aging mechanisms and increase longevity. This paper presents some analogies and some distinctions that exist between the living dissipative structure matter and inanimate matter, discusses the aging process and proposes certain aging reversal solutions.

Role of insulin/insulin-like growth factor 1 signaling pathway in longevity

The insulin/insulin-like growth factor 1 (IGF-1) signaling pathway is evolutionary conserved in diverse species including C.elegans, saccharomyces cerevisiae, Drosophila melanogaster, rodents and humans, which is involved in many interrelated functions that are necessary for metabolism, growth and reproduction. Interestingly, more and more research has revealed that insulin/IGF-1 signaling pathway plays a pivotal role in the regulation of longevity. Generally, disruption of the power of this pathway will extend longevity in species ranging from C.elegans to humans. The role of insulin/IGF-1 in longevity is probably related to stress resistance. Although the underlying mechanisms of longevity are not fully understood, the Insulin/IGF-1 signaling pathway has attracted substantial attention and it will be a novel target to prevent or postpone age-related diseases and extend life span. In this review, we mainly focus on the similar constitution and role of insulin/IGF-1 signaling pathway in C.elegans, saccharomyces cerevisiae, rodents and humans.