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Biomedical subjects

R Hildebrand

Publications and source records attributed to R Hildebrand.

59 records · Page 4Linked to original sources
PubMed1976

[Investigation on the morphokinetic reactions of the rat liver to ether anaesthesia of different length (author's transl)].

The nuclear volumes were measured in the central, intermediate and peripheral zone of the classic liver lobule of adult male albino rats exposed to ether anaesthesia lasting 15, 40 and 80 min. Related to control animals there was a significantly lower nuclear size after a 40 min duration of narcosis and a significant higher volume after 80 min in the central part of the lobule. With a slight but not significant decrease of nuclear volume in the intermediate zone after 15 min and a significant increase after 80 min respectively, the peripheral lobular region constantly showed significantly smaller nuclei. But here, too, a disappearance of decrease was recorded after 80 min. The interpretation of the data is based upon a typical distribution of cell organelles, enzymatic pathways, and metabolites in the different zones of the hepatic lobule. The intensity of reaction and appearance of diminution in nuclear volume, indicating a functional depression and probably accentuated by a circular dependent low O2-tension of tissue, is interpreted in connection with different local concentrations of ether. An improvement of the blood flow by augmental local metabolites and an increased arterial influx presumably support the recovery and favour a concentration-dependent induction of microsomal enzymes in the central part of the lobule especially.

Anesthesia, Inhalation↗
PubMed1975

Influence of intermittent long-term stimulation on contractile, histochemical and metabolic properties of fibre populations in fast and slow rabbit muscles.

Slow (m.soleus) and fast (m.tibialis anterior) muscles of the rabbit were subjected to indirect long-term intermittent stimulation (3 weeks, 8 hrs daily) with a frequency pattern of 10 imp/sec. Whereas no changes were observed in case of the slow muscle, stimulation induced profound changes in the fast tibialis anterior muscle. These consisted in a rearrangement of the enzyme activity pattern of energy-supplying metabolism, e.g. decrease in glycogenolytic and glycolytic enzyme activities and severalfold increase in key enzymes of aerobic endoxidation of substrates in beta-oxidation and the citric acid cycle. Concomitant with the increase in aerobic oxidative capacity, there was an increased resistance to fatigue. Histochemical studies revealed a strong increase in mitochondria of all fibres. The bimodal distribution of fibre cross-sectional area in the normal tibialis anterior muscle was changed by stimulation into a more homogeneous population of fibres with a smaller cross-sectional area. Despite a 50% increase in time to peak of isometric twitch contraction no changes were observed in the fibre population with regard to myofibrillar ATPase reaction in quantitative evaluation of whole cross-sections of the muscles. The percentage of fibres histochemically classified as slow amounted to 2.8% and 3.1% in control and stimulated tibialis anterior muscle. Nevertheless the data suggest a transformation of the fibre population under the influence of long-term intermittent stimulation.

Adenosine Triphosphatases↗
PubMed1975

[Karyometric studies of the pancreas and adrenal glands of the albino-rat fed an unbalanced glucose diet or a glucose diet supplemented with thiamine].

Karyometric measurements in rats which for 30 days had received a glucose diet or a glucose diet supplemented with thiamine showed the following decrease in nuclear size in contrast to no treated controls. (see article) In both experimental groups there was a 30% loss of weight during the course of the experiment. The different decreases in nuclear volume in the examined organs cannot be explained only by a relative state of hunger. The very large decrease in activity in the fasciculated zone of the adrenal cortex is explained as an adaptation mechanism favouring glucose oxidation by insulin, and the relative increase in activity in the adrenal medulla as an adaptation mechanism to accomplish an elevated lipolysis.

Adrenal Cortex↗
PubMed1975

[Significance of tissue specificity for the frequency of mitosis and it's changes (author's transl)].

A 15 fold increase in the rate of mitosis was found in the lower third of the crypts of Lieberkühn in the duodenum of albino rats which had received a dose of colchicine or colchicine after a long treatment with glibenclamid compared with untreated rats. The B-cells of the islets of Langerhans of all rats in the colchicine + glibenclamid group showed however an 18 fold increase in the rate of mitosis in relation to the other two groups. The high number of cells found in the mitotic state in the duodenum of the colchicine treated rats is due to the prevention of further differentiation and hinderance of locomotion of the already high number of cells undergoing mitosis. The B-cells appear to be insensitive to colchicine, probably because they divide only occasionally and tend to remain in the same place, but they are shown to be sensitive to glibenclamid. It is concluded that the influence of external factors on the frequency of mitosis depends primarily on the particular characteristics of the tissue.

Animals↗