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Biomedical subjects

B Moser

Publications and source records attributed to B Moser.

120 records · Page 7Linked to original sources
PubMed1986

Cardiovascular haemodynamics and the response of vasopressin, aldosterone, plasma renin activity and plasma catecholamines to head-up tilt in young and old healthy subjects.

Increasing age impairs the regulation of blood pressure during posture change. The neuro-humoral and cardiovascular responses to head-up tilt were analysed in carefully-screened young and healthy elderly individuals. Mean blood pressure was significantly higher in the elderly but there were no differences in total peripheral resistance, heart rate, stroke volume and cardiac index. Age-related interactions were observed in the control of mean blood pressure, heart rate and stroke volume. Total peripheral resistance increased and cardiac index decreased but there was no difference in their control in the young and old. Noradrenaline, vasopressin, plasma renin activity and aldosterone all increased in response to the tilt. These observations indicate differences in the neuroendocrine responses and cardiovascular haemodynamics of young and old healthy individuals to head-up tilt and are particularly important because of all observations were made simultaneously in the same subject. It is suggested that a similar approach should be adopted in the investigation of patients with postural hypotension.

Adult↗
PubMed1985

The effect of age on the control of water conservation in the laboratory mouse--metabolic studies.

Age-related changes in the intake of food and water, and the output of faeces and urine were investigated in C57BL/Icrfat mice of 6 and 24 months of age. Animals were singly housed in a metabolic cage for a period of 30 days. 14 days were allowed for acclimatization before the animals were dehydrated for 24 hours. 10 days of rehydration were allowed prior to a hyperosmotic challenge with 3% sodium chloride in the drinking water. The animals were then observed for 5 more days of rehydration. Urine was collected and analysed with regard to sodium, potassium, urea and vasopressin output/24 hours (/100g body weight), and the osmotic pressure of the urine was determined. Data were analysed by a 2 factor analysis of variance with repeated measures on one factor. Significant changes were detected in the control of body weight, potassium, sodium and urea outputs. No age-differences were detected in the intake of food or water, the output of faeces or urine, the urine osmotic pressure or the excretion of vasopressin. However, significant changes in these variables were detected in both age groups on the days of physiological challenge. The conclusion drawn is that in the mouse strain studied, and for the period of the lifespan investigated, there is no age related defect in the secretion of vasopressin. However, there are trends in the data suggesting a decreased responsiveness of the kidney with age.

Age Factors↗
PubMed1983

Purification and properties of a mitochondrial NAD+ glycohydrolase.

A 60- to 70-fold purification of an NAD+ glycohydrolase from the inner membrane of rat liver mitochondria to apparent homogeneity on sodium dodecyl sulfate (SDS)-polyacrylamide slab gel is described. The minimum molecular weight of the enzyme on polyacrylamide gels in the presence of SDS is around 62,000. The enzyme splits NAD+ to ADP-ribose and, presumably, nicotinamide. No phosphatase or phosphodiesterase activity is detected in the purified enzyme preparation. The enzyme shows high activity with NAD+ and moderate activity with NADP+ as substrates NAD(P)Hs are poor substrates. ATP and nicotinamide inhibit the enzyme. A possible participation of the enzyme in the mechanism of calcium release from rat liver mitochondria is discussed.

Animals↗
PubMed1983

ADP-ribosylation in inner membrane of rat liver mitochondria.

NAD+ glycohydrolase activity is found at high levels in submitochondrial particles. It leads to the reaction products ADP-ribose, nicotinamide, and small amounts of 5'-AMP. Furthermore, submitochondrial particles catalyze the exchange reaction: [adenosine-14C]ADP-ribose + NAD+ in equilibrium [adenosine-14C]-NAD+ + ADP-ribose. When submitochondrial particles are incubated with NAD+, mono(ADP-ribosyl)ation of protein molecules migrating with an apparent molecular weight of 30,000 in sodium dodecyl sulfate/polyacrylamide gel electrophoresis is demonstrable. Inhibitor studies suggest attachment of ADP-ribose to arginine residues. ADP-ribose bound to submitochondrial particles is rapidly turning over. The release of ADP-ribose from the protein is probably enzyme catalyzed. The rapid turnover, the specificity of the modification, and the inhibition of ADP-ribosylation by ATP and nicotinamide suggest a regulatory role of mono(ADP-ribosyl)ation of a protein in the inner mitochondrial membrane.

Adenosine Diphosphate Ribose↗
PubMed1976

[Reversible hyperplasia and hypertrophy of the mouse liver induced by a functional charge with phenobarbital].

INTRODUCTION: Administration of phenobarbital to rats and mice is well known to cause enlargement of the liver, where the drug is metabolized by hydroxylation and oxydation. The increase of the liver weight is thought to be due to and enlargement of the individual hepatocytes (hypertrophy) caused by an augmentation of the smooth endoplasmic reticulum, as well as to cell multiplication (hyperplasia). The present investigation deals with the nuclear DNA content of mouse hepatocytes during and after administration of different doses of phenobarbital. The data are related to liver weight with due consideration of mitotic activity and cell loss by necrobiosis. MATERIAL AND METHODS: 172 five to six weeks old male albino NMRI mice with a body weight of 23 to 33 gms were randomly divided into four groups, one of which served as the controls. The three test groups received 75 mg and 150 mg phenobarbital per 1 kg body weight intraperitoneally once every day for a total of 10 days. Thereafter the administration of the drug was discontinued. Beginning with the third day of the experiment 3 animals of each group were sacrificed by exsanguination every secound day after their body weight had been carefully determined. Then the liver weights were measured. The nuclear DNA content of the hepatocytes was determined from liver smears by means of acriflavine-Feulgen fluorescence cytophotometry. The number of mitotic figures and of necrobiotic liver cells was counted in histologic sections. RESULTS: With animals receiving 150 mg and 100 mg phenobarbital per 1 kg body weight a rapid increase of the relative liver weight (up to 74% above the controls) was observed, which was reduced back to normal levels within 10 days after discontinuation of the drug. Parallel with the increase of the liver weight a striking DNA-polyploidisation of the liver nuclei occurred which proved to be reversible during the reduction phase. Mitotic figures were found only in the initial phase of the experiment (third to fifth day), while the number of necrobiotic hepatocytes was increased after the drug was discontinued. Similar but markedly less pronounced effects were encountered with animals of the 75 group. DISCUSSION: It is concluded that the increase of the liver weight of mice after phenobarbital administration is partly due to cell multiplication (hyperplasia) - as is shown by a high number of mitotic figures in the initial phase of the experiment-, partly due to the enlargement of hepatocytes with concommitant polyploidisation of the muclei (hypertrophy). When the drug administration is discontinued the liver weights return to normal levels within 10 days. Since at the same time the number of high-ploidy nuclei is reduced with no evidence of an increased mitotic activity, the reduction of the liver weight should be partly caused by an elimination of high-ploidy hepatocytes, which are no longer required after the hyperfunctional stimulus has ceased...

Animals↗