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Biomedical subjects

R Fröber

Publications and source records attributed to R Fröber.

28 records · Page 2Linked to original sources
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

[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↗
PubMed1980

[Immunological and enzymatical activity after dimiimidoester fixation (author's transl)].

The paper is concerned with the capability of diimidoesteras as histochemical fixatives. findings of diimidoester-fixed human erythrocytes show the receptor activity these cells had retained. Due to these properties amidinated red cells proved well suited as storable immunosorbens for ensuing tests of haemagglutination. Following immunisation with horseradish peroxidase of rats, diimidoester-fixed plasma cells were highly reactive towards HRP in contrast to only moderately stained glutaraldehyde fixed cells.

Animals↗
PubMed1979

Rat endo- and mesothelium lack Fc receptors.

The present study is concerned with the interaction of rat endo- and mesothelium with homologous erythrocytes under various conditions of pretreatment and incubation. Its findings show rat endo- and mesothelial cells a) nonadhesive to native or pretreated erythrocytes irrespective of the presence of gamma-globulin in the medium, b) devoid of primary or cryptic receptors sensitive to the Fc segment of the IgG molecule, and c) provided with binding sites at the oxidized glycocalyx which together with receptor groups of modified erythrocytes share the same class of IgG.

Agglutination↗
PubMed1979

[Sialic acid content and IgG binding of the glycocalyx of preserved erythrocytes].

Fractions of light and heavy erythrocytes were separated by centrifugation from blood samples banked in ACD-AG medium at 4 degrees C for periods up to 6 weeks. Both light and heavy erythrocytes have lost about 4,9% of their content of sialic acids during banking for 6 weeks. This reduction is in accord with a 6%-decrease of their agglutination by means of alcian blue. It is, however, a variance with the inhibition of agglutination by anti-IgG sera. The present findings provide evidence for the role alterations of the red cell membrane may play in the process of recognition and phagocytosis of banked erythrocytes. With regard to these alterations we suggest two types of rapid elimination of transfused banked erythrocytes: a) Primary elimination refers to cells primarily loaded with immunoglobulins such as to get recognized and phagocytized by macrophages. b) Secondary elimination accounts for rigid erythrocytes suffering from additional degradation while retained in the spleen prior to their loading with immunoglobulins and ensuing phagocytosis. Secondary elimination is considered a process more relevant to reutilisation of banked blood.

Binding Sites, Antibody↗
PubMed1978

[Environmentally dependent erythrocyte membrane permeability as a source of error in the determination of hematocrit].

The volume of human red blood cells (RBC) was evaluated by means of the centrifugation method (hematocrit) and 131-J-labelled human serum albumin, respectively. Both of the methods yielded an identical volume of about 107 micron3 of the single RBC, provided the evaluation was performed in autologous plasma. Contrary to the 131-J-albumin method the results of which were found independent of various pretreatments of RBC, the centrifugation hematocrits of RBC previously washed with PBS and resuspended in PBS or saline protein media resulted in a mean cell volume of about 86 micron3. The decrease of the cell volume was associated with an efflux of K+ ions. If the RBC are centrifuged at 800 g instead of 15000 g, their volume will remain unchanged. The assessment of cytodeformability has shown, that RBC in PBS by loss of cell volume could enter a 2.3 micron micropipette completely. RBC in plasma, though traversing a 2.9 micron micropipette were incapable of entering a 2.3 micron channel completely. With pressures ranging from 300 to 350 mm H2O the processes of these cells undergo microspherulation.

Cell Membrane Permeability↗
PubMed1978

Glutaraldehyde mediated echinocyte/discocyte transformation is Ca2+ dependent.

Echinocytes, which were produced from freshly banked blood by repeated washes in phosphate buffered saline, undergo a transformation to the discoid shape within less than 30 seconds of incubation in isotonic 0.05% glutaraldehyde pH 7.4. This echinocyte/discocyte transformation is not associated with a change of cell volume or critical hemolysis volume although a slight decrease of cellular deformability and a 4-8 fold increase of K+ efflux within 1 hour after glutaraldehyde incubation provide evidence of the fixative's attack on the cell membrane. Trypsination prior to the incubation in isotonic glutaraldehyde could not inhibit the shape change. Hypertonic glutaraldehyde solutions partially prevent the E/D transformation with regard to both the osmolarity of the medium and the permeability of the cell membrane. The glutaraldehyde stimulated transformation is entirely inhibited in the presence of a chelating agent the efficiency of which is overcome by addition of a more-than-equivalent amount of Ca2+. The mutual action of either agent is discussed, however, the mechanism of the phenomenon remains unclear.

Aldehydes↗
PubMedDate not supplied

Pulmonary atresia with hypoplastic right ventricle. A clinical embryological study.

An unusual case of pulmonary atresia with an aberrant karyotype of 46,XX,t(6;8)(p21.2;q11.2) is reported. Fetal ultrasonic examination at the 20th week of gestation revealed a hypoplastic right ventricle and an intact interventricular septum. Authors summarize their postnatal findings in fetal heart and the large adjacent vessels with special reference to the pathogenesis of this rare congenital heart defect. The observation delineates right-ventricular outflow tract obstruction associated with an abnormal pulmonary blood supply. The anatomy of the systemic pulmonary collaterals was studied and correlated with multifocal disorders in the system of the pharyngeal arch arteries in the early embryonic development.

Amniocentesis↗