Human longevity: an evolutionary approach

Ressignificação existencial do pretérito e longevidade humana

Existem, atualmente, mais de 300 hipóteses relativas à caracterização, função e mecanismos do envelhecimento, possivelmente devido ao aumento de idosos no mundo. Embora se avente uma função social à velhice humana, as transformações da sociedade impuseram uma cultura de descarte, incluindo pessoas como os idosos. Tal exclusão, que se associa à tristeza, depressão e morte desse grupo, é contraditória ao aumento do tempo de vida dos idosos constatado atualmente. O presente trabalho tentou determinar os aspectos ambientais envolvidos na longevidade usando uma técnica de metodologia qualitativa denominada grounded theory (ou teoria fundamentada nos dados) em dados fornecidos por ex-ferroviários longevos. Constatou-se que as representações dos ex-ferroviários confluem para a categoria central: desolação pelo aniquilamento da vida e do ambiente, no presente, devido à continuada negligência do Estado e da Sociedade na promoção e preservação das coisas boas para a vida que havia no passado. Observou-se ainda que, paralelamente à hipervalorização genérica das coisas do passado, há constatação recente de que suas existências fizeram parte da epopeia que promoveu o desenvolvimento econômico e social do interior paulista e possibilitou uma ressignificação existencial do passado, sugerindo ser um potente mecanismo de defesa que culmina em longevidade. Tal achado se insere na hipótese de que a função da longevidade seria a de preservar um contingente social com conhecimentos de um modo de vida que deu certo por ser socialmente vantajoso.

Enrichment of longevity phenotype in mtDNA haplogroups D4b2b, D4a, and D5 in the Japanese population

We report new results from the re-analysis of 672 complete mitochondrial (mtDNA) genomes of unrelated Japanese individuals stratified into seven equal sized groups by the phenotypes: diabetic patients, diabetic patients with severe angiopathy, healthy non-obese young males, obese young males, patients with Alzheimer's disease, patients with Parkinson's disease and centenarians. Each phenotype had 96 samples over 27 known haplogroups: A, B4a, B4b, B4c, B*, B5, D*, F1, F2, M*, M7a, M7b, M8, M9, D4a, D4b1, D4b2, D4d, D4e, D4g, D4h, D5, G, Z, M*, N9a, and N9b. A t-test comparing the fraction of samples in a haplogroup to healthy young males showed a significant enrichment of haplogroups D4a, D5, and D4b2 in centenarians. The D4b2 enrichment was limited to a subgroup of 40 of 61 samples which had the synonymous mutation 9296C > T. We identified this cluster as a distinct haplogroup and labeled it as D4b2b. Using an exhaustive procedure, we constructed the complete list of "mutation patterns" for centenarians and showed that the most significant patterns were in D4a, D5, and D4b2b. We argue that if a selection for longevity appeared only once, it was probably an autosomal event which could be dated to after the appearance of the D mega-group but before the coalescent time of D4a, D5, and D4b2b. Using a simple procedure, we estimated that this event occurred 24.4 +/- 0.9 kYBP.

Time, space and contextual models of the immunity tolerance decision: bridging the geographical divide of Zinkernagel and Hengartner's 'Credo 2004'

In Credo 2004, Zinkernagel and Hengartner (Z&H) have continued their challenge to the immunological community to reconsider assumptions regarding the most fundamental aspects of adaptive immunity. They have appropriately championed the role of persistent, widely distributed antigen in tolerance induction, parameters that do not figure prominently in most other models. The global theory of immunity they have developed is predominantly based on observations from studies with viruses and tumours. I suggest here that a more successful approach to generating a theory of the default rules of immunity can be obtained through the study of immunity versus tolerance in the setting of transplantation. Transplantation studies lack the confounding variable of competing evolution present in responses to specific infectious agents and tumours and, therefore, more clearly elucidate default rules of immunity. The geographical model in Credo 2004, primarily a one-signal model regulated by antigen, is contrasted with (1) Cohn's time-based two-signal model and (2) a development-context model that postulates distinct central and peripheral tolerance mechanisms.

Elevated levels of inducible heat shock 70 proteins in human brain

Differential expression of heat shock genes can modulate protein folding and stress-related cell death. There have been no comparisons of their levels of expression in animals and humans. Levels of expression of heat shock 70 genes in human brain were compared to levels in non-stressed and heat-stressed brain of rat. Levels of hsp70 proteins in human brain were 43-fold higher than in non-stressed rat brain and 14-fold higher than highest induced levels in brains of heat-shocked rats. Levels of constitutively synthesized hsc70 proteins were approximately 1.5-fold higher in human than in rat. Higher levels of hsp70 proteins in human brain may serve to protect brain cells against stress-related death or dysfunction throughout the lifespan.

Latest advances in antiaging medicine

Rapid progress is being made in our ability to modify the aging process. Rather than serving as a period of debility and decreasing health, for many people, the later years of life are becoming a period of continued productivity, independence and good health. Progress is also being made in increasing average lifespan. The leading causes of death (cardiovascular disease, cancer, lung disease, diabetes) are the end result of decades-long processes. With current knowledge, it is possible to delay the onset of these diseases. This can be assisted by lifestyle choices incorporating healthful diet, exercise, stress management, and nutritional supplementation. Emerging genomics technology will allow individuals to establish personalized programs, while early detection of heart disease and cancer will contribute to longevity. Biotechnological therapies involving stem cells, recombinant DNA, proteomics, therapeutic cloning and gene-based therapies are expected to play major roles in promoting successful aging. We are at the threshold of artificial intelligence (AI) and nanotechnology (NT). AI will allow for a merging of our biological thinking with advanced forms of non-biological intelligence to vastly expand our ability to think, create and experience. NT will ultimately allow us to build devices able to build molecules much like our current cellular machinery does, one atom at a time. It is the goal of today's antiaging medicine to forestall disease and aging long enough for people to utilize the powerful biotechnology and nanotechnology therapies that will be developed over the decades ahead. These future therapies have the potential to greatly extend longevity.

The Sun determines human longevity: teratogenic effects of chaotic solar radiation

An association between fertility and longevity has been known for many years, and considerable research has been focused on the mechanisms of ageing that ultimately determine longevity, which has remained essentially unchanged despite a near doubling of human life expectancy in the past 200 years. In this paper, the authors present evidence that the Sun determines the limits of longevity for the longest-living complex organisms. The Sun is a dynamical system and although solar cycles occur every 8-14 years (averaging approximately 11.1 years), the authors show that 28% of these cycles exhibit chaotic features and irregularly release up to 300% more ultraviolet radiation than usual. These chaotic solar cycles create an environment mutagenic to DNA that must be largely avoided in order to pass uncorrupted genes to the next generation. This requirement determines the limits of fertility, e.g., menarche and menopause in humans, and sets longevity to approximately 100 years.

Programmed death phenomena: from organelle to organism

Programmed death phenomena appear to be inherent not only in living cells (apoptosis), but also in subcellular organelles (e.g., self-elimination of mitochondria, called mitoptosis), organs (organoptosis), and even whole organisms (phenoptosis). In all these cases, the "Samurai law of biology"--it is better to die than to be wrong--seems to be operative. The operation of this law helps complicated living systems avoid the risk of ruin when a system of lower hierarchic position makes a significant mistake. Thus, mitoptosis purifies a cell from damaged and hence unwanted mitochondria; apoptosis purifies a tissue from unwanted cells; and phenoptosis purifies a community from unwanted individuals. Defense against reactive oxygen species (ROS) is probably one of the primary evolutionary functions of programmed death mechanisms. So far, it seems that ROS play a key role in the mito-, apo-, organo-, and phenoptoses, which is consistent with Harman's theory of aging. Here a concept is described that tries to unite Weismann's hypothesis of aging as an adaptive programmed death mechanism and the generally accepted alternative point of view that considers aging as an inevitable result of accumulation in an organism of occasional injuries. It is suggested that injury accumulation is monitored by a system(s) actuating a phenoptotic death program when the number of injuries reaches some critical level. The system(s) in question are organized in such a way that the lethal case appears to be a result of phenoptosis long before the occasional injuries make impossible the functioning of the organism. It is stressed that for humans these cruel regulations look like an atavism that, if overcome, might dramatically prolong the human life span.

Mitochondrial physiology and pathology; concepts of programmed death of organelles, cells and organisms

The review summarizes the present state of our knowledge concerning alternative functions of mitochondria, namely energy conservation in forms of protonic potential and ATP, thermoregulatory energy dissipation as heat, production of useful substances, decomposition of harmful substances, control of cellular processes. The recent progress in understanding of some mitochondrion-linked pathologies is described. The role of reactive oxygen species in these processes is stressed. Possible mechanisms of programmed death of mitochondrion (mitoptosis), cell (apoptosis) and organism (phenoptosis) are considered. A concept is put forward assuming that mitoptosis is involved in some types of apoptosis whereas apoptosis can be a part of a phenoptotic cascade. It is hypothesized that septic shock, as well as the stress-induced brain and heart ischemic diseases and cancer, exemplify mechanisms of phenoptosis purifying population, community of organisms or kin from dangerous or useless individuals.