摘要:

The paper presents experimental data on extrathyroidal metabolism of thyroid hormones in rats of various ages (1.5–32 months): T4-131I distribution in an organism, indices of T4 and T3 kinetics, tissue deiodinative capacity, formation of T4 tissue metabolism products and their clearance from cells and organism, T4 binding with tissue proteins. Essential changes in T4 peripheral tissue metabolism have been found with aging: T4 binding by tissues is decreased; T4 distribution space and metabolic clearance are increased; 125I clearance with urine is decreased; T4 half-time in blood remains unchanged; tissue deiodinative capacity is enhanced. Indices of T3 peripheral metabolism in old rats remain unchanged. All these findings result in shifts of the T4/T3 ratio in favour of the latter and in invariability of its content in tissues, alongside with a decrease of functional activity of the thyroid gland with agin

ISSN:0304-324X    

DOI:10.1159/000212240

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The rates of restitution of skeletal muscle, heart, and brain creatine phosphate and brain ATP, following experimental depletion, were compared in young (3–5 month), adult (12 month) and old (24 month) rats. In skeletal muscle, restitution of creatine phosphate after 3 min of recovery was greatest in the young rats, minimal in the adult animals, and absent in the old animals. In heart muscle, on the other hand, restitution was rapid in all three age groups, and was essentially complete after 60 sec recovery. In brain, restitution of creatine phosphate was rapid and was complete after 10 min recovery in the young and adult rats; restitution was slower and less complete in the old rats. In the old rats there was no restitution of brain ATP during the first 2 min of recovery, after which the rate of restitution paralleled that of the young and adult rat

ISSN:0304-324X    

DOI:10.1159/000212241

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Diiodomethane at a concentration of 10 μg/ml increased the median life span of the fruit fly, Drosophila melanogaster, by 29.3%. Decreased flight activity was associated with increased longevity when the flies were reared and maintained on diiodomethane. Rearing only on diiodomethane increased life span by 13.6% and eliminated the decreased-flight-activity phenomenon. The effects of iodine, iodoform and hydriodic acid on longevity were also examined

ISSN:0304-324X    

DOI:10.1159/000212242

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Serum lysozyme activity was determined in 135 healthy people classified into five different age groups ranging from 20 to 90 years. A turbidometric method with egg-white lysozyme as standard enzyme using the Fragiligraph for automatic recording of the serum lysozyme was used. The results show a progressive increase in serum lysozyme activity with age. In the oldest age group of 60–90 years, the increase in serum lysozyme was more than that expected for the diminished glomerular filtration rate in old age. Since the serum level of lysozyme can reflect the rate of neutrophilic turnover, it can be assumed that this rate increases above the age of 6

ISSN:0304-324X    

DOI:10.1159/000212243

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Dietary intake, sunlight exposure and 25-hydroxy-vitamin D levels were estimated in 62 patients admitted to a geriatric assessment unit. There was a significant correlation between vitamin D intake and 25-hydroxy-vitamin D levels but none between sunlight exposure and these. This suggests that in old age dietary deficiency may be a more important cause of metabolic bone disease than limited sunlight exposure.

ISSN:0304-324X    

DOI:10.1159/000212244

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Whereas gerontologists usually regard ageing as an intrinsic process that increases the risk of death, investigators of coronary heart disease (CHD) tend to believe that its causes are largely environmental. If the latter view is correct and if the same is true of many other fatal diseases (as is commonly alleged), then gerontologists should not regard the age pattern of mortality in a population as an index of ageing. An attempt is made in this paper to assess the roles of intrinsic and extrinsic factors in the aetiology and pathogenesis of CHD. The analysis is carried out in terms of the author’s theory of age-dependent autoaggressive disease although the conclusions are largely independent of that theory. Two parameters of the mathematical formulation of the theory prove to be important in this context: S, the fraction of the study population that is genetically predisposed to fatal CHD, and λ, the average latent period between the end of the intrinsic stochastic process of initiation and death from CHD. From published studies it is shown that the ‘risk factors’ cigarette smoking, high relative weight and (probably) hypercholes-terolaemia associate only with λ and not with S. High levels of each of these factors associate with low values of λ. However, the ‘risk factors’ lack of exercise, hypertension and diabetes mellitus associate with both S and λ. The associations with S probably have a straightforward genetic interpretation: persons genetically predisposed to lack of exercise, hypertension and diabetes mellitus are more likely – at least in various Caucasian populations – to be genetically predisposed to CHD than persons in the general population. Our main problem, therefore, is to decide whether the negative associations between the level of a risk factor, and the average duration, λ, of the latent period, should be interpreted in ‘causal’ and/or genetic terms. Secular (temporal) trends in sex-specific and age-specific death rates from CHD in England and Wales, from 1921 to 1973, are illustrated and they give no indication of any appreciable shortening in λ – in spite of increases in some major risk factors. The average latent period remains at about 10 years for men and 20 years for women throughout the period. A wide range of other pertinent epidemiological evidence is reviewed, all of which is consistent with the genetic interpretation and much of which is inconsistent with the ‘causal’ interpretation of the associations between the classical risk factors and λ. (There is no doubt, however, that high death rates from CHD immediately following extremes of environmental temperature should be attributed to a causal mechanism.) Theory predicts that, at high levels, the classical risk factors will not be independent. Recent epidemiological studies confirm this prediction. It is improbable that the classical risk factors make any appreciable causal contribution to the pathogenesis of CHD, but even if they do, the intrinsic biological process of initiation dominates the age dependence of CHD. Similar considerations extend to other major fatal diseases. In regarding the age pattern of mortality in medically advanced countries as resulting predominantly from the phenomenon of biological ageing, gerontologists are unl

ISSN:0304-324X    

DOI:10.1159/000212245

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0304-324X    

DOI:10.1159/000212246

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0304-324X    

DOI:10.1159/000212247

出版商:S. Karger AG    

年代:1978

数据来源: Karger