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W Linss

Publications and source records attributed to W Linss.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1983

Acceleration of coagulation by spectrin-free erythrocytic vesicles. Evidence for lipid flip-flop during vesicle formation.

Spectrin-free erythrocytic vesicles isolated from outdated liquid-preserved blood samples show a distinct increase of the clot-promoting activity compared with membrane phospholipid equivalents of intact erythrocytes. We suppose that, among other remodelling processes, local spectrin detachment from the inner membrane surface may trigger a flip-flop-mediated disturbance of the membrane lipid asymmetry. The interactions of spectrin with the cytoplasmic membrane surface seem to be essential for the structural membrane integrity including the lipid asymmetry.

Blood Coagulation↗
PubMed1983

[Ultrastructural findings on cell extrusion of intestinal villi in mice].

Ultrastructural findings at the extrusion zone on the tips of the Villi intestinales in the jejunum of mice showed that the estrusion of cells can take place in various ways. One possibility is that, at first, a part of the cell is protruding into the lumen under reduction or loss of the microvilli. The rest of the cell is following, but the continuity of the epithelium is preserved. The cell remains adhered to its neighbours which adjoin in such a way that not gap can develop in the epithelium. Often the plasmalemma of the extruding cell is completely preserved. Sometimes a breaking up can be observed. Then the cytoplasm enters the intestinal lumen. On the other hand, the enterocyte can leave the epithelium after widening of the intercellular space and destruction of the cell connection. Then a gap is established and direct contact between the intestinal lumen and the basement membrane.

Animals↗
PubMed1983

Membrane alteration during banking of red blood cells.

Irreversible RBC membrane alterations take place during liquid storage (whole blood, RBC concentrates). Major membrane lesions are conformational changes of glycophorines, number reduction of A determinants and NaNa containing negatively charged groups, loss of phospholipids, expression of IgG receptors, redistribution of spectrin and vesiculation. Effects of these changes on the rheological and immunological cell properties as well as their importance for RBC elimination after reinfusion are discussed. Preliminary studies show that low temperature preservation of RBC (-25 degrees C) stabilizes the RBC membrane more extensively than liquid storage techniques.

Blood Banks↗
PubMed1982

Metabolic depletion of erythrocytes is accompanied by a decrease of sialic acid during blood bank storage: a reply.

Erythrocytes lose about 10% of their sialic acid during banking in ACD-AG medium. In contrast to these findings, Pessina et al. could not detect a significant banking-related sialic acid decrease. The present paper explains this discrepancy. The vesiculation of erythrocytes is mainly responsible for the observed sialic acid loss during blood preservation.

Blood Preservation↗
PubMed1982

[Erythrocyte vesiculation. 3. Building block analysis of vesicles from preserved blood].

The contents of total protein, haemoglobin, hexose, phospholipid and sialic acid of erythrocytic vesicles prepared from ACD-AG blood samples banked for 6 weeks were analyzed quantitatively. The results were discussed and compared with those of other authors. The bulk of vesicular haemoglobin is not released under hypotonic conditions. It can be determined with the haemiglobincyanide method in the presence of SDS.

Blood Preservation↗
PubMed1982

[Vesiculation of erythrocytes. 4. Quantification of vesiculation rates in standard fluid preservation].

The quantity of erythrocytic vesicles was estimated, which were produced after 6 weeks banking of ACD/AG and CPD/AG blood samples. The analytical and morphological dates of these vesicles allow calculation leading to the following conclusions: 1. After 6 weeks storage under blood banking conditions about 210 vesicles per erythrocyte were formed. 2. The vesiculation may serve as a possible explanation for storage dependent losses of sialic acid as well as phospholipids. 3. The vesiculation is accompanied by a reduction of the surface/volume ratio of the erythrocytes. This may be an important fact regarding the elimination of a part of stored cells via decreasing deformability of the red blood cells.

Blood Preservation↗
PubMed1982

[The altered membrane of the erythrocyte. I. Ultrahistochemical and biocellular investigations for the detection of activated acetylcholinesterase (ACHE) and demasking of IgG receptor sites (author's transl)].

Different states of the erythrocyte membrane with regard to its disintegration are characterized. The binding power of autologous and allogenic IgG, the degree of the activation of the membrane associated acetylcholinesterase (inhibited in the intact plasmalemma of red blood cells), and the membrane vesiculation served as criteria. The findings demonstrate that, obviously, the IgG binding increases in dependence on the extent of the disturbance of the membrane structure. The acetylcholinesterase is increasingly activated. The enzyme can be demonstrated by spectrophotometrical and ultrahistochemical methods. Microvesiculation is understood as expression of fundamental disturbances of the membrane structure. These disturbances express local remodelling processes in the membrane of banked red blood cells. Highly extended damage of red blood cells after mechanical stress, heat or urea incubation lead to comparatively high rates of vesiculation, partially even to cell fragmentation. Extremely spectrindeficient ghosts tend to microvesiculation, which leads to complete microvesicular decay of the ghost membrane. The membrane associated autologous IgG is demonstrated by means of immuneological and ultrahistochemical methods. Its importance as homeostatically effective immun-signal for the elimination of red blood cells aged in vivo or in vitro, ghosts and microvesicles by the reticulohistiocytic-system is evidenced by means of model experiments. Molecular mechanisms for unmasking of IgG-receptor sites and activation of acetylcholineesterase in the altered erythrocyte membrane are discussed.

Acetylcholinesterase↗