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Biomedical subjects

W Linss

Publications and source records attributed to W Linss.

At least 55 records · Page 3Linked to original sources
PubMed1987

Red blood cell aging--membrane skeleton alteration and IgG receptor expression.

Investigations were performed on aging of erythrocytes. It has been assumed that structural changes of the membrane result after exposer of the cells to certain environmental influences in vivo or in vitro. Cell aging can be connected with varying combinations of membrane structure disturbances. It is postulated that the messenger which signals membrane structure lesion is involved in a mechanism given by the expression of immunoglobulin G (IgG) receptor sites which bind autologous IgG1 and IgG3. This antibodies are cytophilic for macrophages. The performed studies demonstrated that an intact molecular arrangement of the membrane skeleton is not only a supposition for stabilization of the membrane asymmetry but also for IgG receptor masking to prevent an early elimination of the red blood cells from the organism.

Erythrocyte Aging↗
PubMed1986

The rate of lateral diffusion of phospholipids in erythrocyte microvesicles.

31P-NMR spectra of phospholipids in membranes of erythrocyte microvesicles isolated from outdated blood units were recorded in the temperature range 5 to 55 degrees C. Within that range the lineshape is strongly influenced by an increasing rate of lateral diffusion of phospholipids. At 36 degrees C a diffusion constant, D, of (2 +/- 1) X 10(-12) m2/s was obtained. The diffusion rate is by a factor of 3 to 10 greater than in erythrocyte membranes measured by the photobleaching technique and is comparable with values obtained for several lipid model membranes. The differences in lateral diffusion rates are probably connected with the depletion of microvesicle membranes in membrane proteins.

Blood Viscosity↗
PubMed1986

Cytochemical and cellbiological investigations of the signal function of the erythrocyte plasmalemma--the membrane structure as code for cell life span.

The erythrocyte membrane was characterized with regard to its alteration of different degrees. A very important process of the membrane alteration is the expression of IgG receptor sites, which is connected with the binding of autologous IgG at the membrane. Several detection methods for membrane bound IgG were described: immunocytochemical techniques (Anti IgG--Anti Ferritin-sandwich technique, Anti IgG-Protein A-Gold- and the Silver enhancement technique), Antiglobulin agglutination test (Coombs test) and erythrocyte-macrophage test. Moreover, the topo-optical toluidine blue reaction and the ultra-histochemical NAD(H) oxidase reaction were checked to characterize the erythrocyte-macrophage interaction. Finally, the microvesiculation is understood as special form of the erythrocyte membrane disintegration, which is connected with a remodelling of an intact plasmalemma. The findings presented here summarize the fact that the membrane associated IgG regulates an immune-signal for the elimination of the erythrocytes in the Reticulo-Histiocytic-System in vivo and in vitro. Therefore, the structural integrity of the erythrocyte plasmalemma is the code for the cell life span.

Animals↗
PubMed1986

Immunocytochemical investigations of the membrane of experimentally altered and physiologically aged erythrocytes.

The expression of IgG receptor sites during aging of red blood cells plays an important role in the elimination process of these cells by the Reticulo Histiocytic System. By means of an indirect protein A gold-method, membrane bound IgG was detected immunocytochemically on pronase and neuraminidase treated red blood cells as well as on physiologically aged red cells. The silver enhancement of the gold particles led to an improved labeling of the bound IgG favouring its quantification at both electron and light microscopic level. The result of this gold-silver-technique was analyzed semiquantitatively at the light microscopic level by use of a Vickers scanning microdensitometer. It was shown that the aging of erythrocytes as well as the enzymatic alteration of the erythrocyte glycocalyx by pronase and neuraminidase are accompanied with an unmasking of IgG receptor sites followed by an IgG loading of the cells in presence of autologous serum or plasma. The experimental results, which are presented here indicate that a silver enhancement of gold particles is sufficient to signalize changes in membrane bound ligands at low concentrations.

Animals↗
PubMed1986

[Intermediate filaments in cells of hyaline cartilage].

After different fixation procedures great numbers of bundles of intermediate cytofilaments, 10 nm in thickness, could be detected in electron micrographs of chondrocytes from Processus xiphoideus of the rat, from the articular cartilage of the rabbit and from chondrocyte cultures from the articular cartilage of the rabbit. By means of the indirect immunofluorescence technique with monoclonal antibodies they could be clearly defined as vimentin.

Animals↗
PubMed1985

[Topographic studies on the pathogenesis of postoperative pareses in the area supplied by the brachial plexus].

Post-operative palsies of the Plexus brachialis innervation area induced post mortem studies on the behaviour of the nerves in 11 positions of the stretched arm. The tension of the Plexus brachialis and of the Nervus ulnaris was measured. It was highest at an abduction of 90 and 120 degrees with additional retroversion. When the abduction is 90 and 120 degrees an anteversion of 15 degrees leads to an ambiguous diminution of the tension.

Aged↗
PubMed1985

Evidence for erythrocyte-microvesiculation in vivo.

During physiologic aging, erythrocytes (RBC) mainly loose membrane as shown by biochemical investigations. The most likely reason for a such loss would be the pinch off of RBC-microvesicles. The detection of RBC-microvesicles generated in vivo is rendered more difficult because of the relatively small amount of vesiculation processes under physiologic conditions accompanied by the fast phagocytosis of RBC-microvesicles in the reticulo-histiocytic system. The latter has been shown after the intravenous injection of heat-induced RBC-microvesicles. Investigations of spleens resulted in the case of PHZ-treatment, up till now in a clear demonstration of RBC-microvesicles. The result of microvesiculation in the PHZ-model led to the conclusion, that also rigid, naturally aged RBC could pinch off microvesicles in physiologic narrows of the blood flow like in the spleen.

Animals↗
PubMed1984

Activation of acetylcholine esterase (ACHE) as a sign for erythrocyte membrane alteration.

In vitro activity determination of membrane bound acetylcholine esterase (ACHE) of intact erythrocytes and differently altered RBC forms by means of the ELLMAN method yielded increase in activity in erythrocyte/vesicle mixtures and ghosts. Alteration of the cells by treatment with periodate, neuraminidase and trypsin leads to no, weak or clear decrease in the activity of this enzyme. Old cells also show a clear decrease in activity. When cells were treated with diamide ACHE is at first functionally inhibited, finally, however, it reaches supernormal values of activity. Possible causes for the different behaviour of ACHE in dependence on the degree of alteration of the erythrocytes are discussed. The results of the measurements were compared with the ultrahistochemical ACHE reactions according to KARNOVSKY (thiocholine--copper ferricyanide method) and IWAYAMA (lead thiocholine method). The influence of several components of the KARNOVSKY'S histochemical reaction mixture on ACHE activity was tested. The investigations suggest that disintegration of the erythrocyte membrane is accompanied with activation of the ACHE molecules which are nearly inactive in the intact membrane. This activation contributes to the positive histochemical ACHE test, which is an indicator reaction of membrane disintegration. Nearly intact membranes show a negative reaction. On the basis of these results we could show that physiological enucleation of normoblasts is connected with the formation of disintegrated membrane areas and their discharge from the future reticulocyte membrane.

Acetylcholinesterase↗
PubMed1984

[Possibilities for the use of cerium for the ultrahistochemical demonstration of enzymes].

The activity pattern of NAD(H)- or NADP(H)-oxidase was studied ultrahistochemically by means of the Cer-III-perhydroxide technique according in Briggs et al. (1979) in erythrophagocytosis. In contrast to many other findings in activated polymorph nucleated neutrophils the activity of this enzyme is restricted to rER and the intracellular vacuoles in peritoneal macrophages. Plasmalemma and the membranes of phagosomes are negative. The results allow the conclusion that oxidases do not directly participate in erythrocyte catabolism. Their role is still unclear. Additionally an ultrahistochemical procedure which used Cer-III-=ions as capture agent for detection of acid phosphatase is presented. The results are compared with the classical lead methods. Cer-IV-ions selectively enhance the electronmicroscopic contrast of biomembranes.

Acid Phosphatase↗
PubMed1984

[Biochemical and morphologic studies on the effect of bile acids on the epithelium of the rat jejunum].

The influence of bile salts on the mucosal surface of rat jejunum was tested with an in vivo technique of segmental perfusion. Sodium taurocholate and chenodesoxycholate were applied in a concentration of 3 mmol/l. The release of 5 brush border membrane enzymes, 5 cytosolic, 1 mitochondrial, and 2 lysosomal enzymes during a perfusion time of 150 min as well as morphological alterations after bile salt treatment were investigated. Among the membrane enzymes, due to their superficial localization, the solubilization of enteropeptidase and alpha-1,4-glucosidase was highest both in the control perfusion and in the presence of bile salts. At the same time, cytoplasmic enzyme activities were liberated extensively whereas lysosomal and mitochondrial enzymes were scarcely detectable. This disproves any serious injury of the enterocytes. Electronmicroscopic results supported this suggestion. After administration of taurocholate (in physiological concentration), only an occasional diminution of the glycocalyx was observed and even chenodeoxycholate (in an unphysiological concentration) caused only negligible destructions of intestinal brush borders. Investigations with ruthenium red to contrast the glycocalyx showed a partially unchanged structure. Microvesiculation from the microvilli was observed in many electron microscopic photographs. That is a possibility for the release of membrane-bound and cytosolic enzymes without destruction of enterocytes.

Animals↗
PubMed1984

Remarks on the role of microtubules in enucleating normoblasts.

In enucleating normoblasts single microtubules are often arranged in a perinuclear position. Sometimes it seems that microtubules attach at the nucleus membrane. Also bundles of microtubules can be found, but a subplasmalemmal microtubular "hoop" does not exist. Colchicine does not influence the process of enucleation. It is concluded that microtubules do not participate in the expulsion of the nucleus during enucleation.

Animals↗
PubMed1984

The histochemical detection of acetylcholine esterase--an indicator of the disintegration of membranes.

The presence of ACHE in erythrocytes membrane in vitro but not detectable ultrahistochemically has been explored as a sign of membranes disintegration. The final results of the investigations have shown, that the increase in ACHE activity of the erythrocyte membrane is a qualitative sign and a semiquantitative measure of serious disturbances in the membrane structure.

Acetylcholinesterase↗
PubMed1984

[Electron microscopic observations on the extrusion of enteroendocrine cells from the epithelium of the mouse small intestine].

By means of electronmicrographs it could be showed that enteroendocrine cells at the tips of the villi intestinalis are extruded in a way similar to other intestinal cells. They lose their contact to the basal lamina. An at first small process protrudes into the intestinal lumen. The cell as an entity can follow afterwards. Frequently this extrusion takes place together with neighbouring cells and as a consequence, there is a cell complex in the intestinal lumen which can be connected with the epithelium by means of a small cytoplasm bridge. A second way leads over rupturing of the protruding part of the cell and the extrusion of the cell residue.

Animals↗