To age or not to age

According to the antagonistic pleiotropy theory of ageing, natural selection has favoured genes conferring short-term benefits to the organism at the cost of deterioration in later life. The 'disposable soma' theory expresses this as a life-history strategy in which somatic maintenance is below the level required to prevent ageing, thus enabling higher immediate fertility. It has been argued that a non-ageing strategy will always be bettered by a low but non-zero rate of ageing, because the costs of such ageing will be felt only in the distant future when they are of negligible importance. Here, we examine this argument critically. We find that a non-ageing strategy will be locally optimal if, in the presence of ageing, the onset of deterioration is sufficiently rapid or early. Conversely, ageing will be optimal if deterioration is sufficiently slow or late. As the temporal profile of ageing changes from one of steady deterioration to one involving a sudden loss of vitality after a period of little or no decline, the conditions for a non-ageing strategy to be locally optimal become progressively more stringent. But for all forms of profile considered, conditions can be found for which a strategy involving no ageing is locally optimal.     

Biological age versus physical fitness age

A population of healthy middle-aged (n = 69) and elderly men (n = 12), who participated in a health promotion program, was studied to determine whether really physically fit individuals are in good biological condition, and also whether improvement of physical fitness in the middle-aged and the elderly reduces their "rate of aging". Biological and physical fitness ages of the individuals studied were estimated from the data for 18 physiological function tests and 5 physical fitness tests, respectively, by a principal component model. The correlation coefficient between the estimated biological and physical fitness ages was 0.72 (p less than 0.01). Detailed analyses of the relationship between the estimated biological and physical fitness ages revealed that those who manifested a higher ("older") physical fitness age did not necessarily have a higher biological age, but those who manifested a lower ("younger") physical fitness age were also found to have a lower biological age. These results suggested that there were considerable individual variations in the relationship between biological condition and physical fitness among individuals with an old physical fitness age, but those who were in a state of high physical fitness maintained a relatively good biological condition. The data regarding the elderly men who had maintained a regular exercise program indicated that their estimated biological ages were considerably younger than the expected values. This might suggest that in older individuals regular physical activity may provide physiological improvements which in turn might reduce "the rate of aging".     

Fecundability and husband's age

The effect of husband's age on the probability of conception is evaluated from World Fertility Survey data in five developing countries: the Ivory Coast, Ghana Kenya, the Sudan, and Syria. Proportional hazards models, which include wife's age, husband's age, marriage duration, union type, and post-partum exposure as covariates, are used to describe the monthly conception rate for second and higher-order birth intervals in which no contraception was used. With the exception of Syria, the resulting models indicate that the effects of male age are generally small in relation to the influences of marital duration and the age of the woman.     

Influence of mouse age and erythrocyte age on glutathione metabolism.

In order to determine whether the biological age of a mouse influences erythrocyte metabolism and erythrocyte aging in vivo, blood samples were collected from male C57/BL6J mice of different biological ages ranging from mature (10 months) to "very old" (37 months). In the very old mouse, compared with the mature mouse, the erythrocyte survival time was decreased, erythrocyte densities were increased, the concentrations of total free thiol and reduced glutathione, and glutathione reductase activity were decreased. Erythrocytes were separated into different density (age) groups by phthalate ester two-phase centrifugation or by albumin density-gradient centrifugation. The density-age relationship of erythrocytes was established by pulse-labelling with 59Fe in vivo and by subsequent determinations of specific radioactivity of erythrocyte fractions of different densities prepared during a chase period of 60 days. The age of erythrocytes in mice of all ages was directly related to density. Also, in older erythrocytes compared with younger erythrocytes, decreased concentrations of total free thiol and reduced glutathione, and decreased glutathione reductase activity were observed. These were the lowest in the old erythrocytes of very old mice. These results in aging erythrocytes from aging mice suggest that the glutathione status the erythrocyte may be an index of aging, not only of the cell but also of the organism.     

Determination of age and age classes of Akodon olivaceus in Southern Chile

Age and age classes in Akodon olivaceus brachiotis were determined by means of a modification of the method used by Sluiter (1961) to quantify tooth wear. Ten age categories were obtained. From April to July the population was mainly composed of young animals. From November to March the population was heterogeneous due to the coexistence of new‐born animals and animals born in the previous reproductive season.     

Sex and age specificity of susceptibility genes modulating survival at old age

OBJECTIVE: We aimed to investigate the influence of the genetic variability of candidate genes on survival at old age in good health. METHODS: First, on the basis of a synthetic survival curve constructed using historic mortality data taken from the Italian population from 1890 onward, we defined three age classes ranging from 18 to 106 years. Second, we assembled a multinomial logistic regression model to evaluate the effect of dichotomous variables (genotypes) on the probability to be assigned to a specific category (age class). Third, we applied the regression model to a cross-sectional dataset (10 genes; 972 subjects selected for healthy status) categorized according to age and sex. RESULTS: We found that genetic factors influence survival at advanced age in good health in a sex- and age-specific way. Furthermore, we found that genetic variability plays a stronger role in males than in females and that, in both genders, its impact is especially important at very old ages. CONCLUSIONS: The analyses presented here underline the age-specific effect of the gene network in modulating survival at advanced age in good health.     

Skeletal age, dental age, and the maturation of KNM-WT 15000

The skeleton of the Homo erectus boy from West Lake Turkana, Kenya (KNM-WT 15000), is remarkably complete, and this individual has thus provided a case study for several researchers examining Homo erectus growth. Using data from a longitudinal study of Montreal French-Canadian children, it is shown that while dental and skeletal ages match reasonably well at the level of a sample of children, individuals can display differences between skeletal and dental ages of 2 years or more. Furthermore, the relationship between these two markers may change over time in individual children. It is also possible to find children with patterns of dental maturation similar to KNM-WT 15000's pattern in the Montreal sample. Therefore, neither the discrepancy between skeletal age and dental age alone nor the pattern of dental maturation as assessed by dental stages precludes a human-like pattern of growth, including an adolescent growth spurt, for this individual. Some indicators (e.g., estimated body size for predicted age, and enamel formation) do suggest possible growth-patterning differences from modern humans, and therefore earlier maturation is a reasonable hypothesis, but caution is warranted, given the large degree of modern human variation in developmental markers and the inherent uncertainty in precise estimation of KNM-WT 15000's maturational parameters.     

Correlation between chronological age and skeletal age using cvmi and modified MP3 methods

Chronological age conveys only a rough approximation of the maturational status of a person whereas skeletal maturity indicators give a more accurate estimation. Therefore, it is of interest to document the correlation between chronological and skeletal age using CVMI and modified MP3 methods. A total of 39 subjects between the age ranges of 9-16 years were selected for this study. Pre-treatment lateral cephalograms and hand-wrist radiographs of the subjects were used. The skeletal age was analyzed by the Cervical Vertebrae Maturity Index (CVMI) and modified MP3 methods. The data was analyzed with SPSS software version 23.00. Kendall''s Tau correlation test was performed to estimate the correlation between chronological age and skeletal age among the subjects and a linear regression test was also performed. Positive correlation was found between chronological age and skeletal age assessed by CVMI method (r= 0.398) and modified MP3 method (r=0.382) with p value >0.003. Thus it can be concluded that there was a positive correlation between chronological age and skeletal age among all the subjects.     

QALYs, age and fairness

... We can therefore conclude that either we should go for equality; and in that case QALYs are unfair because they haven't got enough of an ageist bias. Or we should accept consequentialism; and in that case QALYs have just the right sort of ageist bias. No plausible case can, however, be made for the claim that QALYs have an unfair bias against old people. Other things being equal we ought when distributing resources essential for survival favour the young. This ethical claim can be supported both by reference to equality (the life-time-view) and by reference to consequentialism (and the premises that resources generally will be more useful when given to young people).     

Allergy and the atomic age

Traumatic peripheral nerve lesions characteristically result in denervation muscular atrophy. Atrophy of disuse may take place concomitantly, either proximal, adjacent to or distal to the denervation muscular atrophy. The degree of atrophy of disuse depends upon the severity of the nerve lesion. Clinically, it is difficult to determine where true denervation muscular atrophy ends and accompanying atrophy of disuse begins. In such circumstances a clinician may be misled into belief that the cause of so apparently extensive a lesion is elsewhere. The patient then is often submitted to other complex diagnostic procedures and treatments. This difficulty can usually be dissipated by the use of electromyography, for each specific type of muscular atrophy produces its own characteristic electromyographic changes. Disuse atrophy produces no changes in electrical activity, whereas denervation atrophy manifests itself by typical denervation activity. Moreover it is possible to determine what part of muscular atrophy in a given area is owing to damage to a nerve and what part is owing only to disuse without denervation.     

Population age structure and recent

Mid to late 20th century expansion of Dracophyllum scrub into tussock grassland on subantarctic Campbell Island has been attributed to the collective effects of global warming, cessation of farming in 1931, and continued grazing by feral sheep. To determine the importance of these, we dated the timing of scrub expansion by aging 241 Dracophyllum plants in 17 plots chosen to sample the range of environments this shrub/ small tree occupies on Campbell Island. Three plots, in lowland, well-drained, locations were dominated by large, old Dracophyllum that had established between 1846 and 1940. Virtually all shrubs in the remaining plots had established after 1940, with peaks in 1970 and 1985. The pattern of establishment does not coincide with any marked change in the temperature regime, although a prolonged period of relatively dry winters (c. 1970–1990) coincides with a late surge of regeneration on very wet sites. The removal of feral sheep from different parts of the island at different times is also unrelated to the pattern of establishment. In contrast, Dracophyllum spread follows farm abandonment in 1931 when regular burning ceased, suggesting that Dracophyllum is invading sites from which it was excluded by fire. However, the earliest reports from the mid 19th century indicate that tussock grassland was previously the dominant vegetation cover on the island, with limited Dracophyllum scrub. It is possible that the reduction of the dense tussock grasslands by fire and grazing in late 19th–early 20th century opened a regeneration window for Dracophyllum scrub to spread once burning ceased.     

Human mutations and paternal age

Summary Attention is drawn to recent findings reported in the literature on paternal age effects in sporadic cases with Marfan's syndrome. It is further shown that in 4 of 6 series with bilateral retinoblastoma a moderate influence of father's age can be detected. The difficulties of interpreting this observation are discussed. Based on the well-known decline in paternal age since the turn of the last century, it is finally estimated that the relative incidence of mutations to achondroplasia has decreased by about one fifth in Norway and France.