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Biomedical subjects

W Linss

Publications and source records attributed to W Linss.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1981

Lipid segregation from human erythrocyte tethers.

Fluid shear force may deform point-attached erythrocytes to become droplike shaped and anchored by a single long or 2-4 short tethers. By addition of glutaraldehyde to the medium the cells were fixed such as to stabilize this deformation for ensuing SEM, freeze-fracture, fine structural, and ultrahistochemical studies. Freeze-fracture specimens revealed identical numbers and distribution patterns of membrane particles in both the membrane of tethers and of the droplike portions of red cells. Segregated vesicles most often were located adjacent to the attachment site of the tether. All of the vesicles were devoid of membrane particles. Irrespective of their length, the tethers were about 0.1 micrometer in diameter. Cross-sections of the tether membrane and the plasmalemma of the major part of the cell appeared identical. Ultrahistochemical studies revealed the same intensity of iron binding capacity and affinity to ferritin labelled anti AHP at either area of the deformed erythrocyte membrane. Segregating vesicles were also stained by colloidal iron and by fer-anti AHP. By means of the DAB-reaction no haemoglobin was demonstrated within the vesicles. All of these findings corroborate the notion, that lipid molecules were segregated from the membrane whose curvature increased considerably during the formation of the tether.

ABO Blood-Group System↗
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↗