Biomedical subjects
R Hildebrand
Publications and source records attributed to R Hildebrand.
Sinusoidal profiles of lactate dehydrogenase activity in rat liver.
Lactate dehydrogenase activities were measured along two sinusoidal paths (1) between small portal tracts and central veins and (2) between regions of adjoining septal branches and central veins in the livers of male Wistar rats, using a Lowry technique. The established profiles of enzyme activity provide further support of functional heterogeneity of liver sinusoids and their abutting hepatocytes related to morphological differences of the sinusoidal bed. Within the hepatocytes a pronounced heterogeneity in enzyme activity was recorded surrounding small portal tracts and central veins. The lowest values of activity were determined in those cells located in close proximity to the vessels, which emphasizes their exceptional morphological and functional position.
[Bijoux anatomiques--the microscopic injection specimens of the Vienna anatomist Joseph Hyrtl (1810-1894)].
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Image analysis of the histochemical demonstration of glucose-6-phosphatase activity in rat liver.
Activities of histochemically demonstrated glucose-6-phosphatase were quantified by computerized densitometry using image analysis in livers of female adult Wistar rats fed ad libitum and fasted 22 h before sacrifice. Mean optical densities along the path between small portal tracts and efferent hepatic venous branches and enzyme activities obtained from biochemical assays exhibited a strong positive correlation. The gradients of high periportal to lower perivenous glucose-6-phosphatase activities were analysed by profiles of optical density along these distances. Mapping optical densities in an image of equidensity range provided information on the distribution pattern of hepatic glucose-6-phosphatase over an extended two-dimensional area. This visualisation of histochemical enzyme reaction based on quantitative data supports the approach of sampling across the entire protal----hepatic venous distance disregarding parenchymal zonation. Utilities provided by computer assisted image analysis will have some bearing for further adequate quantitative description of liver function and structural make up.
[Johannes Müller and Friedrich Schlemm, Ernst Heinrich and Eduard Friedrich Weber, Bernard von Langenbeck and Johann Christian Jüngken in the drawings of the portrait artist J. Kayser].
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Eine unveröffentlichte Notiz Cajals zu den Cajalschen Zellen von Retzius.
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[Bourgery and Jacob, Hirschfeld and Léveillé--masterpieces of anatomical iconography in the heyday of lithography].
The Traité de l'Anatomie by Bourgery and Jacob and the Néurologie by Hirschfeld and Léveillé are among the best works in medical iconography. They are considered to rank in importance with other magnificent atlases due to their excellent plates and precise descriptive text. They set an new standard in anatomical illustration and made the artist devoted to anatomy a scientific collaborator of his scientist in anatomy.
Explorative studies on karyometric frequency distributions. I. Quantitative description and comparison of curves with 2 maxima.
A mathematical procedure is introduced describing frequency distributions of nuclear size with 2 maxima sufficiently by the evaluation of three parameters which are directly representative for the curves: the positions of the first and second maximum and the percentage ratio of the first maximum related to the second maximum. This approximation is a prerequisite to statistical comparison and interpretation of the curves.
Binucleate cells and liver karyometry.
Liver karyometry of uni- and binucleate cells was compared with karyometric measurements excluding binucleate cells in pervinous regions of rat liver parenchyma. Depending on their percentage of the cell population and due to their smaller nuclear size binucleate cells decrease nuclear volume means and the main maximum of frequency distributions of nuclear size (karyometric curves) but increase the lower second maximum in the range of smaller nuclear volumes. The main characteristics of the course of the curves, however, remain unchanged.
Explorative studies on karyometric frequency distributions. II. Approximation using normally distributed curves versus median interpolation.
An approximation using normally distributed curves and a median interpolation were applied to frequency distributions of nuclear size with one maximum. Both methods gave the same results as far as the positions of the curves on the axis of nuclear volume classes were concerned. Further detailed information on the course of the curves by the median interpolation, however, may be falsified by artificial differences due to the interpolation.
Karyometry of nuclei in liver cells. Heterogeneity of nuclear volume and percentage of binucleate cells associated with veins.
In untreated adult male albino rats nuclear volume and the percentage of binucleate cells were determined in the first layer of hepatocytes adjacent to hepatic venous branches of varying diameters (less than 40 microns, 40 microns-80 microns, 80 microns-120 microns, 120 microns-160 microns, greater than 160 microns), and in the third and fourth layer of hepatocytes in the remainder of the perivenous parenchyma. In the first layer of hepatocytes adjacent to the vascular structures means of nuclear volume are significantly lower and percentage of binucleate cells significantly higher than in the cells of the remainder of the perivenous parenchyma. Within each area measured distribution curves of nuclear volume classes were homogeneous but showed heterogeneity in comparison with each other. The morphometric data presented in this study strongly support the opinion of the heterogeneity of liver cells in the perivenous zone, as previously postulated on the basis of histochemical investigations.
Microbiochemical investigation on diurnal rhythmic changes of the activities of the lactate dehydrogenase in the periportal and perivenous zones of the acinus of the rat liver.
Activities of the lactate dehydrogenase within the periportal zone and within the perivenous zone in the first layer of hepatocytes adjacent to terminal hepatic venules and the remainder of the perivenous parenchyma of the liver acinus were measured using a Lowry technique during a full 24-h cycle (08.00-08.00) in untreated adult male Wistar rats kept under 12 h of light and 12 h of darkness, scotophase 18.25-06.25. In all three regions studied a broad first maximum was recorded between 10.00 and 22.00 with the peak value at 16.00 and a high and narrow peak at 24.00. Zonal and intrazonal heterogeneity of the lactate dehydrogenase were retained during the full day and night cycle. The regions displayed individual dynamic changes in enzyme activity.
Quantitative and qualitative histochemical investigation on NADP+-dependent dehydrogenases in the limiting plate and the residual parenchyma surrounding terminal hepatic venules.
Activities of three NADP+-dependent enzymes (glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, isocitrate dehydrogenase) were demonstrated in the first layer of hepatocytes adjacent to terminal hepatic venules (perivenous limiting plate), and in the residual parenchyma of the perivenous zone of the acinus, in normally fed adult male Wistar rats, using a Lowry technique and a qualitative histochemical staining reaction. Enzyme activities of the glucose-6-phosphate dehydrogenase were significantly higher in the hepatocytes adjacent to terminal hepatic venules (ratio hepatocytes adjacent to terminal hepatic venules/residual parenchyma of the perivenous zone: 1.31). 6-Phosphogluconate dehydrogenase and isocitrate dehydrogenase were homogeneously distributed in the two areas measured (ratio: 1.04 and ratio: 1.0 respectively). With the qualitative histochemical staining reactions no differences were found.
Problems in fitting a cosine curve.
In fitting of cosine curves latent experimental inequalities due to a serial effect have to be excluded. Though cosinor analysis may be sufficient then, inclusion of biological time, i.e. not fitting values to time but to a function of time, will lead to further improvement.