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Biomedical subjects

W Linss

Publications and source records attributed to W Linss.

At least 91 records · Page 5Linked to original sources
PubMed1981

Erythrocyte vesiculation. 2. Membrane molecular transformation.

A population of vesicles 150 +/- 30 nm in diameter was isolated from banked human blood and the perturbation of their membrane studied. SDS polyacrylamide gel electrophoresis revealed the complete loss of spectrins from the vesicle membrane which was also depleted of various intrinsic proteins. In particular, severe reduction of protein 3 and glycophorin is consistent with the over 80% decline of intramembrane particles in either fracture face of the vesicle membrane. The stimulation of vesicle acetylcholinesterase is considered indicative of an initial disintegration associated with the segregation and rearrangement of membrane constituents. The findings are discussed with regard to the subcellular mechanisms of erythrocyte vesiculation.

Blood Preservation↗
PubMed1981

[Importance of the cell membrane for the sequestration of aged erythrocytes].

The erythrocyte membrane is an important cell organelle which determines the intravital life time of the cell in a decisive way. Their mechanic properties are closely connected with the metabolism of the cells. Increasing disturbance of the cellular metabolism especially in the course of biological aging leads to enhanced cell rigidity. It is supposed that the decreased elasticity of the aged erythrocytes in critical regions of the blood circulation (capillaries with a diameter of 2.5 to 3.0 micrometers) leads to pressure induced vesiculation and spherocytosis. It is possible that also IgG-receptors are demarked by this process. After passing a threshold concentration as immunobiological signals increased irreversible binding of IgG induces the sequestration of the erythrocytes by the erythrocyte destructing system.

Animals↗
PubMed1981

Defined rearrangement of the membrane of banked erythrocytes.

Segregation of integrated proteins, detachment of actin and spectrin from cytoplasmic aspect as well as decomposition of phospholipids may cause the release of vesicles from spicula of banked erythrocytes. The findings provide evidence for a mechanism of plasmalemmal rearrangement, because a clear distinction between the protein composition of the vesicle membrane and of the erythrocyte plasmalemma could be shown. The vesiculation mechanism is discussed.

Actins↗
PubMed1981

[Maturation processes in the plasmalemma of erythroid cells].

Quantitative studies of the enucleating normoblast show that the plasmalemma envelope of the nucleus under extrusion and this of the nucleus that appear to be extruded bind more autologous IgG than the plasmalemma of the future reticulocyte. This finding explains the quick phagocytosis of the extruded nuclei by macrophages. In addition heaps of small vesicles free from haemoglobin are found at the enucleating normoblasts and at the reticulocytes. They bind cationized ferritin and autologous IgG. They are interpreted as segregation of constituents of the plasmalemma during red blood cell maturation.

Binding Sites, Antibody↗
PubMed1981

[Production and extracellular arrangement of proteoglycans in the growing hyaline cartilage].

Fixation of hyaline cartilage with potassium ferricyanide in addition to glutaraldehyde and osmium tetroxide leads to a better stabilization of the glycosaminoglycans. The resulting chelate formation enhances the electronmicroscopic density. In active chondrocytes electron dense material is found intracellularly in the rough endoplasmic reticulum, in transport vesicles, in the Golgi apparatus and in big vacuoles. Intercellularly large amounts of the glycosaminoglycans are preserved. The correlations between the macromolecules and the collagenous fibrills are demonstrated.

Animals↗
PubMed1981

[Genesis of microcytes in hemodialysis patients with chronic uremia].

The study is concerned with factors that may reduce the life time of erythrocytes of patients under intermittent haemodialysis. The red cell population of these patients consisted of micro-, normo-, macro- and megalocytes. The classification of the cell size was shiftet to greater diameters in comparison with healthy donors. The evaluation of the biological half time of erythrocytes labelled with 51Cr resulted in a decrease of about 16 days. The autoradiographic evaluation of the erythrocyte size-distribution patterns 1 and 24 hours after the injection of labelled red cells into the donors circulation clearly demonstrated a decrease of macro- and megalocytes. Simultaneously, the number of microcytes rose considerably. The measurement of erythrocyte deformability could demonstrate a clearcut relationship of flexibility for a) disturbed erythropoiesis resulting in the production of macro- and megalocytes, and b) fragmentation and premature elimination from the circulation due to unfavourable rheologic properties of erythrocytes of abnormal big and small sizes.

Autoradiography↗
PubMed1980

Lipid segregation from the maturing erythroid cell membrane.

Vesicles attached to the cell membrane of enucleating normoblasts and reticulocytes are considered indicative of the segregation of plasmalemmal components. The vesicles are obviously free from haemoglobin. They bind cationized ferritin and autologous immunoglobulin G. This segregation of plasmalemmal constituents is suggested to be one line of erythroid cell maturation.

Animals↗
PubMed1980

DNase--a likely probe of juxtatranscriptional DNP.

The acridine orange-DNase sequences applied to rat lymphoid cells resulted in granular products within the cell nucleus. Staining with uranyl acetate rendered the granules very opaque. Most of the coarse deposits lay adjacent to condensed chromatin. Minute granules were found in dispersed chromatin as well as in the nucleolus and in heterochromatin regions. Phosphotungstic acid staining revealed the protein constituents of these deposits. The procedure is suggested an electron microscopic demonstration of DNase protein bound to acridine orange modified beaded chromatin juxtaposed to transcription units.

Acridine Orange↗
PubMed1980

Erythrocyte hypotonic lesion stimulates plasmalemmal acetylcholine esterase.

Contrary to the rather high amount of acetylcholine esterase, histochemical methods revealed only an insignificant activity of that enzyme in the erythrocyte plasmalemma. Following hypotonic incubation many damaged red cells whether or not hemolyzed were heavily loaded with reaction products on the outer aspect of their membrane. The findings are consistent with a suggested allosteric activation of acetylcholine esterase in the moderately disintegrated cell membrane. Thus, the cytochemical demonstration of acetylcholine esterase is considered a means to assess the plasmalemmal integrity of individual red cells.

Acetylcholinesterase↗
PubMed1980

IgG binding sites of the enucleating normoblast membrane.

The binding of autologous immunoglobulin G to the membrane of the enucleating rabbit normoblast was studied by means of light and electron microscopic immunohistochemical methods. In comparison with the future reticulocyte membrane, the plasmalemmal envelope of the normoblast nucleus under extrusion displays a high affinity to IgG.

Animals↗
PubMed1980

[Inverse binding of lectin to either area of the plasmalemma of the enucleating normoblast (author's transl)].

The study was concerned with properties of either area of the cell membrane of the enucleating erythroblast, i.e. the plasmalemma envelope of the nucleus under extrusion and the future membrane of the reticulocyte. The findings did not corroborate the notion of a decline of the negative surplus charge of the plasmalemmal envelope. At this area of the erythroblast membrane it was demonstrated an increased lectin binding associated with the loss of toluidine blue induced anisotropy.

Cell Nucleus↗
PubMed1979

Hypotonic unmasking of erythrocyte receptor sites.

The study reports on plasmalemmal perturbation of erythrocytes under osmotic stress. In comparison with isotonic human erythrocytes a 10 minutes incubation in 150 mosm sodium cacodylate pH 7.4 at 20 degrees C results in an increase of the anti AH P binding rate by a factor of two. 0.1 M N-acetyl galactosamine inhibits the binding of anti-AH P of both isotonic and hypotonic red cells. Contrary to isotonic mouse erythrocytes the agglutination with peritoneal murine leukocytes of hypotonic red cells is greatly enhanced provided the erythrocytes have been incubated in autologous serum. The findings are considered evidence of the unmasking of binding sites due to nonspecific rearrangement of membrane constituents.

Acetylgalactosamine↗
PubMed1979

Alteration of the enucleating erythroblast glycocalyx.

Plasmalemmal differentiation of the enucleating normoblast of rabbit and rat was studied by means of cytochemical methods and freeze-etching. Staining with colloidal iron revealed about identical amounts of iron particles bound to various areas of the normoblast membrane. Cationized ferritin and ruthenium red, likewise, failed in the demonstration of significant changes of the enucleating normoblast glycocalyx. Despite these findings the topo-optical staining with toluidine blue showed the plasmalemmal envelope of the protruding normoblast nucleus moderately birefringent, clearly discriminated from the intense anisotropic staining of the future reticulocyte membrane. The ferritin-labeled snail lectin anti AHP localized a great number of binding sites at the plasmalemmal envelope of the nucleus under extrusion. That is in sharp contrast with rather low lectin binding to the future reticulocyte membrane which amounts to about 30 to 50% of the nuclear envelope label. The findings provide evidence of unmasking of bindings sites of the normoblast membrane. Apparently, the effect is due to conformational changes of the cell membrane, rather than it could be attributed to degradation of glycoproteins. Moreover, enucleation kinetics may also be related to supramolecular changes of membrane structure albeit missing evidence for the rearrangement of membrane particles.

Animals↗
PubMed1979

CPC-PTA section staining of acid glycans.

A cetylpyridinium chloride-phosphotungstic acid procedure suggested by Kelényi and Kiss (1976) for the staining of mast cell granules in ultrathin sections was slightly modified with regard to pretreatment, pH of incubation, and rinsing of sections. The method also proved suitable for the demonstration of various mucosubstances and of cartilage proteoglycan aggrebates.

Animals↗
PubMed1979

Negative surplus charge of coated erythrocytes.

The effect on the net negative surface charge of single or multiple coating of erythrocytes was studied on human group A red cells previously washed and fixed. Single coating with either group A antiserum or protectin decreased the electrophoretic mobility of erythrocytes by 16% and 13%, respectively. Following an incubation in group A glycophorin or bovine submaxillary mucin of agglutinin coated cells, the electrophoretic mobility was restored or slightly increased compared with uncoated erythrocytes. Upon repeating this scheme, the second agglutinin binding again reduced these cells' cytophoretic mobility, and they were accelerated once more by a second coating with acid glycoprotein. Intensity and homogeneity of colloidal iron staining of uncoated and variously coated erythrocytes reflected their electrophoretic retardation and acceleration, respectively.

ABO Blood-Group System↗