[Age-related characteristics of the effect of potassium glutamate on cell membranes]

The effect of potassium glutaminate on the activity of some enzymes and lipid peroxidation of liver and kidney endoplasmic reticulum membranes was studied in young and old rats. It was shown that in old animals, the drug increased the activity of enzymes of liver endoplasmic reticulum membranes which metabolize the substances of endogenous and exogenous origin, and reduced the renal content of malonic dialdehyde, the final product of lipid peroxidation. The latter favoured the improvement of drug biotransformation and elimination of the aging body.

An adventitious role of cortisol in degenerative processes due to decreased opposition by insulin: implications for aging

Cortisol can be implicated as contributing to a number of degenerative processes including arteriosclerosis, atherosclerosis, diabetes, and deterioration of muscle and the immune system. These effects of cortisol are amplified in diabetes due to a diminished opposition by insulin. In addition, this phenomena may not be restricted to diabetes. There is evidence that tissue sensitivity to insulin generally decreases with age, although insulin levels and metabolism may remain constant; this is not generally true for cortisol. This results in an increased cortisol activity with some pathological consequences which are most evident in vascular connective tissue and the immune system. The decrease in tissue responsiveness to insulin with respect to cortisol may reflect relative aging differences in the corresponding receptor-effector systems.

Temporal advancement of diethylnitrosamine carcinogenesis in aging mice

Female BALB/c mice were given diethylnitrosamine (DEN) in their drinking water beginning at 2.5, 9.5, and 17 months of age (cumulative dose approximately 300 to 400 mg/kg body weight) or were untreated. Median times of death for the treatment groups were 193, 168, and 125 days, respectively, after cessation of DEN treatment and were significantly different (p less than .01). Induced tumors in the three respective age groups were of squamous forestomach (88, 87, and 84%), vascular tumors of the liver (11, 13, and 16%), and adenomas of the lung (65, 56, and 54%). Controls had no forestomach or liver tumors and relatively low incidences of lung tumors. The fact that aging mice have similar incidences and types of tumors of the same size and in the same tissues, but at an earlier time, shows that (1) DEN is carcinogenic in aging BALB/c mice; (2) age at treatment does not alter the tumor-susceptible tissue nor types of tumors after DEN treatment; (3) tumor incidences are not affected by age at time of treatment; (4) mice die earlier with induced tumors with increasing age at time of treatment; (5) age-matched non-DEN-treated mice die from different diseases (leukemias) than do DEN-treated mice (stomach and liver tumors). These observations may be related, in part, to an identified age-dependent decrease in immunocompetency or to other age-related changes, such as vascular or hormonal, which could explain temporal advancement in the tumorigenic process.

[Age-related characteristics of thyroxine action on the cytochrome content in rat liver mitochondria and on body weight]

Content of cytochromes a (a3) was decreased and the ratio c/a/a3/ was increased in rat liver mitochondria depending on animal age. Administration of thyroxine incresased the level of cytochromes. These phenomena were especially distinct in 12- and 24-month old rats. The latent period, manifested as a decrease in body mass, was the characteristic property of the tyroxine effect in the young animals. Age differences in the effect of thyroxine depend also on the dose of the hormone.

On the role of cross-linking of cellular proteins in aging

Water-insoluble protein fractions increase in the brain cortical tissue and liver of rats during aging in both sexes. This suggests a possible increase in the cross-linking of proteins which may be due to the formation of, for example, hydroxyl free radicals during several metabolic processes. In vivo application of centrophenoxine causes a reversal of this phenomenon in old rats. In vitro experiments show that the generation of hydroxyl free radicals by chemical systems like homolysis of H2O2 by redox coupling with Fe2+ leads to Fe3+ conversion, results in the cross-linking of bovine serum albumin and the mixed proteins of liver or brain homogenates of young rats. The cross-linked proteins have a very much increased molecular weight, they become mostly insoluble even in 6 M urea. Dimethylaminoethanol, the effective part of the centrophenoxine molecules, is able to diminish the extent of cross-linking, acting most probably as a free-radical scavenger. The results are discussed in terms of the "membrane hypothesis of aging". A molecular basis is proposed for the anti-aging effect of centrophenoxine.

[Effect of estradiol dipropionate on cell membrane electrical properties and their electrolyte makeup in animals of different ages]

Intraperitoneal administration of estradiol dipropionate (EDDP) leads to membrane hyperpolarization, the growth of its resistance, reduction of cell excitation and potassium and sodium ions redistribution on both sides of the membrane. In old animals the shift of the membrane potential occurred in response to half estrogen doses (50 microgram) in comparison with that in adults, this pointing to greater sensitivity of the muscle cells of old rats to EDDP. The protein biosynthesis inhibitors prevented development of hyperpolarization, changes of electrical properties of the membrane and ionic shifts usually following estrogen administration. Elimination of the EDDP effect in old animals was reached with lesser doses of the protein biosynthesis inhibitors.

Effect of treatment with phenformin, diphenylhydantoin or L-dopa on life span and tumour incidence in C3H/Sn mice

The chronic treatment of female C3H/Sn mice with phenformin (2 mg/day) and diphenylhydantoin (2 mg/day) prolonged mean life span by 23 and 25%, respectively, and decreased spontaneous tumour incidence by 4.0 and 2.3 times, respectively. The chronic treatment of mice with L-dopa (2 mg/day) did not change these parameters and decreased the multiplicity of mammary tumours. The mechanisms of the drug action on mouse life span and tumour incidence are discussed.

Androgen and estrogen conversion rations in aging women

Androgens and estrogens labeled with 3H- and 14C- have been infused at constant rates into postmenopausal women whose ages ranged from 45--90 yr, and who were 1--40 yr postmenopausal. The conversion ratios (ratio of concentrations of radioactivity as infused precursor to product steroid) for interconversions of androstenedione to testosterone, for the conversions of androstenedione and testosterone to dihydrotestosterone and for the interconversions of the estrogens were calculated. There was no trends in the conversion ratios with age and the mean values for these ratios in these postmenopausal women did not differ significantly from their respective values in a group of normal, healthy, reproductive-aged women. Our data are compatible with the conclusion that the overall activities of certain 17 beta-dehydrogenases and 5 alpha-reductases do not decrease appreciably with age.

The relationship of age and drinking habits to the effects of alcohol on memory in women

When given a moderate dose of alcohol, both middle-aged women and women who were moderate drinkers retained less on 2 different types of memory tasks than did young women and women who were light drinkers.

Alcohol and the aging process in social drinkers

Social drinkers' performance on tests of abstracting and concept formation declined significantly as a function of age and of the quantity of alcohol consumed per drinking occasion.

Singlet oxygen and aging in Drosophila

There was little or no improvement in the median survival times of Drosophila melanogaster fruit flies when fed high concentrations of the singlet oxygen quenchers, beta-carotene and 1,4-diazabicyclo(2.2.2)octane. Singlet oxygen was presumably generated endogenously by inactivating catalse with 3-amino-1,2,4-triazole and feeding NaOCl. This treatment caused reduction in median life span of from 14.3 to 25% depending upon the NaOCl concentration used. beta-Carotene and 1,4-diazabicyclo(2.2.2)octane gave partial protection against the singlet oxygen generated by NaOCl. These data are interpreted to mean that normally occurring singlet oxygen does not contribute to senescence in Drosophila but that artificially produced singlet oxygen accelerates the rate of aging.