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Biomedical subjects

H Martin

Publications and source records attributed to H Martin.

644 records · Page 36Linked to original sources
PubMedDate not supplied

[Biologic aging. 22. Oxygen and aging].

By means of the experimental-gerontological literature the question of causality between oxygen and ageing and the age-associated alterations, influencing oxygen utilisation, were discussed. Under normal conditions there are no significant decreases of high-energy compounds in the most organs, although under a strain of organism it is possible to show a reduction of adaptation and regulation on different levels. Oxygen deficiency as a primary cause of ageing could not be showed experimentally. On the other hand the classification of free radicals (= the products of oxygen activation) as primary factors of ageing are more conceivable. The estimation of causal relations is difficult because of the interlocking of physiological and pathological processes of ageing.

Adenosine Triphosphate↗
PubMedDate not supplied

[Age dependent changes in signal transduction of glucocorticoid hormones after physiological stress in liver cells of male Wistar rats].

After physiological stress older male Wistar rats showed a faster normalization of the corticosterone level in serum and of the concentration of unoccupied glucocorticoid receptors in liver cytosol than young ones, which is contrary to female rats. The nuclei binding of glucocorticoid receptor complexes (GRC) was significantly reduced in older control animals compared with young ones. The nuclei binding of GRC was reduced in young rats until 60 min after stress compared to controls, whereas it had been increasing in older animals at this time. Contrary to female rats, the addition of the endogenous ATP-stimulated translocation promoter (ASTP) alone or together with ATP did not elevate the nuclei binding, but it groups. Crossing experiments using nuclei of controls and GRC of control and stressed animals, resp., seem to disclose a longer association of GRC with the nuclei in old animals than in young ones.

Aging↗
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[Biology of aging].

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Aging↗
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[Effect of cytoplasmic factors on cell nucleus binding of glucocorticoid receptor complexes in the rat liver of two age groups].

The nuclei binding of activated glucocorticoid receptor complexes (GRC) was significantly diminished in old, unstressed rats compared with young ones. In animals killed at different times after physiological stress there were no significant age-dependent differences in nuclei binding of GRC, which recurred in the cytoplasm after 60, 120 and 180 min, resp. Addition of Ca2+ and ATP, resp., to the incubation system increased the nuclei bound part of GRC, especially in young animals. ATP-stimulated translocation promoter (ASTP), isolated from rat liver cytosol, raised the nuclei binding of GRC in both age groups, whereby the increase was only significant in young animals. In cytosol of old rats ASTP were found in a lower concentration; moreover, the reaction between ASTP, GRC, and the template seems to be impaired.

Adenosine Triphosphate↗
PubMedDate not supplied

[Enzyme adaptation and "vitauct" process].

The existence of a so-called "vitauct process" is discussed by means of the glucocorticoid-induced stimulation of tyrosine aminotransferase activity. Own experiments show that the highest possible stimulation of the enzyme by cortisol and stress in the liver of old Wistar rats is not lower than in young-adult animals. After stress and 4 h after cortisol injection of 0.75 mg/100 g b.w. even a higher sensitivity seems to exist. A main problem for the interpretation of the results is the treatment of the control animals. Stress-free animals and animals to which the hormone-free solvent only under light ether narcosis was injected i.p. (stressed controls) were used. With the lowest injected hormone dose (0.25 mg cortisol/100 g b.w.) the results lie below those of the stressed controls. As a result of the findings of this paper, of the role of the enzyme, and of different influencing factors (e.g., glucocorticoid receptors) we suggest that the used model does not allow a conclusive decision about the existence of a vitauct process.

Adaptation, Physiological↗
PubMedDate not supplied

[Obesity, malic enzyme and aging--an animal experiment study].

In male Wistar rats the influences of age and experimental obesity on the activity of malic enzyme (EC 1.1.1.40) in different organs were studied. Obesity was induced in newborn rats by injection of Na(+)-L-glutamate (2 mg/g b.w. daily) subcutaneously in the first 5 days. The enzyme activity was measured at the ages of 2, 6 and 18 months. In control animals the highest enzyme activities were found in the heart muscle, liver, epididymal fat pad and skeletal muscle after 6 months. After 18 months the activities in these organs are considerably reduced. In the kidneys the activity between the 2nd and the 18th months tends to decrease continuously and only the brain shows an opposite trend. In comparison with the control animals, in glutamate treated rats the enzyme activity doubles nearly in the lipogenic organs liver and fat tissue in all age groups. In liver and fat tissue of 6-month-old rats, previously treated with clonidine to stimulate growth hormone secretion, the activities are lower than in glutamate obese rats without clonidine, but still higher than in normal control animals. The qualification of glutamate obese rats as a model for the study of age-associated diseases like obesity or diabetes mellitus type II needs further investigation.

Adipose Tissue↗
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Somebody to lean on.

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Eye Neoplasms↗