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Biomedical subjects

W Richter

Publications and source records attributed to W Richter.

At least 217 records · Page 12Linked to original sources
PubMed1981

Variations in the appearance of membrane particles after various pretreatments.

In freeze-fracturing human erythrocytes beside the intramembraneous particles fibrillar structures can be observed. They are in close relation to the intramembraneous particles and occur frequently under special conditions. 1. In erythrocytes incubated with MgCl2-solutions (25-100 mM) striking fibrillar structures are mostly located on the E-fracture face or extend from the E-face to the cytoplasmic surface aspect of the membrane. Fibrillar structures located on the P-face or extending from the P-face to the extracellular surface aspect do not often occur. This asymmetrical distribution indicates that elements pulled out from the cytoplasmic membrane half play a special role in the fibril formation. Intermediate forms between particles and fibrillar structures can occur. 2. By use of the microtome technique for freeze-fracturing in a frozen 60 vol.-% glycerol solution at temperatures upward from -100 degrees C melting can occur at the knife edge during cutting. In connection with the formation of a melting zone in isolated erythrocyte membranes incubated in 60 vol.-% aqueous glycerol a somewhat modified (unfinished) membrane splitting is possible. Lying side by side both the membrane fracture halves remain connected by the unsplit part of the membrane. In the region where they are connected fibrils between the two fracture faces occur indicating a deformation process during the particle formation. The results give further evidence that plastic deformation during freeze-fracturing takes place in the formation of the intramembraneous particles in native erythrocyte membranes.

Erythrocyte Membrane↗
PubMed1981

Renal tumors in rats given trisodium nitrilotriacetic acid in drinking water for 2 years.

One hundred and ninety-six albino male rats [Crl/COBS CD (SD) BR] were given 1,000 ppm trisodium nitrilotriacetic acid (NTA) in drinking water for 2 years. One hundred and ninety-two control rats were given water without NTA. Animals that had a palpable mass or that appeared clinically ill were killed. All survivors were killed at 704 days. A significantly (P less than 0.05) higher proportion of the NTA-treated rats vs. 11.2% of the controls). The largest difference between the NTA-treated rats and the controls in tumor incidence was associated with renal adenoma. The NTA-treated group contained 25 rats with renal adenomas and 4 with renal adenocarcinomas. Only 5 control rats had renal adenomas; none had renal adenocarcinomas. No statistically significant differences were observed for any of the other tumor types among the NTA-treated rats and the controls. The overall incidence of renal tubular cell hyperplasia and nephritis was similar in the treated and control groups. However, a significantly greater number of NTA-treated rats had more severe grades of hyperplasia. Thus NTA when administered continuously in drinking water at a concentration of 1,000 ppm is tumorigenic to the rat kidney.

Acetates↗
PubMed1981

[Autoradiographic investigations on postnatal proliferative activity of the matrix-zones of the brain in the trout (Salmo irideus) (author's transl)].

The localization and proliferative activity of the matrix-zones has been investigated in the brains of 60 teleosts (Salmo irideus) by means of autoradiographs, after injection of tritiated thymidine at different stages of the postnatal life. There are no previous detailed autoradiographical reports on postnatal brain development in the trout. Matrix-zones (i.e. ventricular and subventricular zone) exist postnatally in all parts of the teleost brain: we have found these in the forebrain, in many diencephalic recessus, in the optic tectum, in cerebellar valvula and corpus, and in the medulla. The quantitative part of this study indicates high values of the labeling-index at the first days after birth. Then, the labeling-index decreases rapidly up to the 25th day. But also in 2 years old specimen labeled cells were observed in the matrix-zones of the central nervous systems; therefore a few of proliferative capacity remains in adult fishes.

Animals↗
PubMed1981

[Autoradiographic investigations on postnatal proliferative activity of the telencephalic and diencephalic matrix-zones in the axolotl (Ambystoma mexicanum), with special references to the olfactory organ (author's transl)].

The localization and proliferative activity of the matrix-zones has been investigated in the telencephalon and in the diencephalon of 21 axolotls (Ambystoma mexicanum) by means of autoradiographs, after injection of tritiated thymidine at different stages of the postnatal life. There are no previous detailed autoradiographical reports on postnatal brain development in the axolotl. Matrix-zones (i.e. ventricular and subventricular zone) exist in the dorsal part and in the ventral part of the telencephalon, we have found these also in the diencephalon in the wall of the preoptic recessus and ventrally of the habenula. The quantitative part of this study indicates high values of the labeling-index in the early postnatal stages. Then, the labeling-index decreases, but also in 3 years old specimens labeled cells were observed in the matrix-zones of the telencephalon; therefore a few of proliferative capacity remains in the central nervous system of adult axolotls. Labeled cells were also found in the olfactory organ of early postnatal and adult axolotls; these are neuroblasts which have relevance for the regeneration of the forebrain.

Ambystoma↗
PubMed1980

[The effects of various reducing diets in adiposity (author's transl)].

The effects of three different hypocaloric diets on serum electrolytes, metabolites and enzyme activities were investigated for 3 weeks in 40 overweight patients. A 600 kcal mixed diet was as effective with regard to daily weight reduction as complete fasting or a low-energy protein diet. Only the patients of the last two groups complained of orthostatic dysregulation, nausea, headache and dryness of the skin. Neither a decrease in serum potassium, an increase in creatinine nor any other side-effects were observed in the mixed diet group. - Since the 600 kcal mixed diet can be carried out under ambulant conditions it is preferable to the other reducing diets.

Adult↗
PubMed1980

[Chronic insulin overdosage in adult diabetics (author's transl)].

In 12 out of 51 maladjusted diabetics treated with insulin chronic insulin overdosage could be established as the reason. Increasing insulin requirements, avid hunger, profuse sweating, vertigo and emotional lability as well as grossly variable glucosuria are evidence of insulin overdosage. Treatment consists of low reduction of daily insulin dosage.

Adult↗
PubMed1980

Evidence that lipolytic peptide B occurs in the ACTH/MSH-cells of the pituitary and in the brain. An immunocytochemical study of its distribution in correlation to the distribution of neurophysin.

Several lipid-mobilizing peptides occur in the pituitary, among them beta-lipotropin and "lipolytic peptide A and peptide B". The latter two peptides are distinct from beta-lipotropin and appear to be chemically related to the neurophysins. Immunohistochemistry has now revealed that the lipolytic peptide B of the pituitary is localized in the ACTH- and MSH-cells. In addition, immunoreactive peptide B was found in axons of the posterior lobe of the pituitary. Immunoreactive peptide B was found also in nerve fibers and nerve cell bodies in the hypothalamus, particularly in the hypothalamo-hypophyseal tract and in the magnocellular neuronal system. Immunoreactive nerve fibers were numerous also in the periventricular nucleus of the thalamus. The antiserum against peptide B cross-reacts with neurophysin I, and hence, it cannot be excluded that at least part of the immunostaining in the brain reflects the presence of the latter component. However, the regional distribution of immunoreactive peptide B and neurophysin was not identical. Therefore, it is possible that authentic peptide B occurs not only in the pituitary but also in the brain.

Adrenocorticotropic Hormone↗
PubMed1980

Intravascular persistence of hydroxyethyl starch (HES) after serial granulocyte collections using HES in man.

In 30 granulocyte donors undergoing one or more infusions of 6% hydroxyethyl starch (HES) solution plasma HES concentrations were measured by single radial immunodiffusion. Serial HES applications led to a cumulative increase in plasma HES levels. Up to 3 months after the last HES infusion, plasma concentrations in the range of 3 mg/ml were demonstrable. A possible influence of HES deposits upon reticuloendothelial system function is discussed.

Adult↗
PubMed1980

Incidence, pathomechanism and prevention of dextran-induced anaphylactoid / anaphylactic reactions in man.

The symptoms of dextran-induced anaphylactoid/anaphylactic reactions (DIAR) range from skin reactions to severe circulatory shock (severity grades I-IV). The reported incidence of DIAR varies between 0.03% and 4.7%, severe reactions comprising 0.008% and 0.6% resp. Studies to elucidate the pathomechanism of DIAR and to possibly prevent them were made during the last decade: No evidence for a pathogenic role of contaminating macromolecules was found, but the dextran molecule itself could be incriminated as elicitor agent. High titres of dextran reactive antibodies (DRA) of predominantly IgG class are regularly found in sera of patients with grade III+IV reactions. Such DRA reflect immunization with dextran cross-reactive bacterial polysaccharides or native dextran. No DRA of IgE class were found. Presence of high IgG-DRA levels, reduction of complement factor Clq and histopathological findings in lungs, all indicate that DIAR should be classified as aggregate (immune complex) anaphylaxis. Hapten inhibition was therefore proposed to prevent DIAR. Based on positive results in animal models, clinical trials were started 1978. Hitherto, 60 485 patients have been studied. It is concluded that the combined use of preinjection of 20 ml Dextran 1 (Pharmacia AB, Uppsala, Sweden) and infusion of Macrodex or Rheomacrodex improves the safety of dextran administration.

Anaphylaxis↗
PubMed1980

[Testing the effectiveness of cerebrally active drugs. Preliminary communication on a test model for cerebrally active drugs in humans].

In a pilot study the feasibility of a new model in clinical pharmacology was investigated for testing cerebro-active drugs on healthy volunteers. For this study 6 volunteers were examined under room-air conditions (pO2 = 155 mmHg) and under a reduced oxygen mixture (12% O2, 88% N2, pO2 = 89 mmHg). Using the "Wiener Determinationsgeraet" (WDG) the subjects were tested as to their receptivity for complex information, their capacity for assimilating information, their reaction capacity, their reaction speed and reaction reliability. The results showed a stochastic connection between measured values on the WDG and the arterial oxygen partial pressure of the volunteers. These results justify additional studies with the described "hypoxia model" in order to test whether this reduction in capability in the healthy volunteers can be counteracted by application of cerebro-active drugs. This model could be used as a screening test for posology and pharmacodynamic effects in view of the further drug development in phase II studies on a larger number of patients.

Adult↗
PubMed1980

[Autoradiography of neurogenesis and morphogenesis of the regio cingularis of the rat. V. Quantitative examinations of the course of cell migration].

The course of migration has been investigated; the migration begins at the 3rd day after injection of tritiated thymidine, at the 7th day the distribution of labeled cells is stable. The fate of cortical plate indicates 2 subdivisions: an inner zone and an outer zone with cells determinated for the cortical layers respectively following the day of origin. It was also explored the lamination, the speed of migration and the transitory localization of labeled cells.

Age Factors↗
PubMed1980

[Neurohistologic and morphometric examinations of the ontogenesis of the regio cingularis mesoneocorticalis in the rat].

The neuronal structure of the Regio cingularis mesoneocorticalis has been studied by means of GOLGI-impregnated brains of embryonic and neonatal rats. The morphometrical analysis has been carried out at 36 pyramidal neurons from layer V and 18 interneurons of the different ages of animals. We have found two staps of development: continuous growth and rapid development. The most frequent staps of rapid development between the stages P 0 and P 5 and between P 10 and P 15 indicate the influence of extrinsic factors. The connection of the neuron-growth in the late ontogenesis and the embryonic processes of proliferation, migration and lamination is discussed.

Age Factors↗