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Biomedical subjects

K J Halbhuber

Publications and source records attributed to K J Halbhuber.

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

[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↗
PubMed1981

[Electron microscopic autoradiography of semithin sections].

Semithin sections are useful for electron microscopic autoradiography. Compared with highest power electron microscopic autoradiography the employment of thicker sections is connected with the following advantages: a) a decrease of exposition time, b) lower intensity of isotope labelling, c) restriction of chemographic processes. Quantifying big series of radioautograms is facilitated.

Autoradiography↗
PubMed1980

[Inverse pH-dependent shape changes of erythrocytes in the presence of albumin].

A comparative study on the shape of human erythrocytes suspended in 7 different media showed, contrary to the well-known albumin-free case, an enhancement of the number of discocytes and stomatocytes for pH rising in all HSA containing media applied. At the same time, the transmembrane potential as determined by extra- and intracellular pH was lowered in all of 6 media tested. Consequently, there is no simple relationship between the pH-dependent behaviour of cell shape and corresponding changes of transmembrane potential.

Culture Media↗
PubMed1980

Alteration by procaine of spectrin cross-links, deformability, and fluidity related properties of the erythrocyte membrane.

The study on procainized human erythrocytes revealed a) temperature dependent changes of cellshapes, b) a significant increase of deformability, c) low amounts of cross-linked membrane proteins, d) a mean cell volume identical with the volume of nonprocainized cells, e) severe reduction of induced anisotropy, f) no loss of negatively charged groups of the glycocalyx, g) decrease of electrophoretic velocity, h) a significant rise of adhesiveness to glass, and i) increase of agglutinability with antiserum and lectin. The findings are discussed in their relationships to alterations of the molecular structure of the red cell membrane.

Adhesiveness↗