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Biomedical subjects

B Frisch

Publications and source records attributed to B Frisch.

7 recordsLinked to original sources
PubMed1978

Cell junctions in dyserythropoiesis.

Erythroid cell junctions have previously been reported in some cases of dyserythropoietic anaemia. This study has demonstrated that they are a relatively common occurrence in dyserythropoiesis. They range from apposition of cellular membranes with preservation of the intercellular space, to membrane confluence, to interdigitation and septate-like junctions. By special staining with colloidal lanthanum, ruthenium red and tannic acid, together with studies of the effect of proteolytic enzymes, their structural composition has been identified and it was confirmed that they are not artefact. The role of cell junctions in dyserythropoiesis is discussed.

Anemia↗
PubMed1978

Localization and role of calcium in the erythrocyte coat: effects of enzymes and storage.

The effects of various treatments on erythrocyte shape, surface, cell coat and calcium binding sites have been investigated by means of high voltage electron microscopy (HVM), scanning electron microscopy (SEM) and conventional electron microscopy (TEM). Papain caused the formation of small blisters within the cellular surface as well as crenation and 'budding' of the erythrocytes. After neuraminidase treatment, long filaments were observed to radiate from the surface of the erythrocyte. The other enzymes investigated, RNA'se DNA'se, phospholipase, protease and trypsin, produced no demonstrable effect on the cellular structure, nor (with the possible exception of trypsin) on the cell coat as seen by subsequent staining with ruthenium red. Putative calcium binding sites on and in the erythrocyte membrane were demonstrated. Following incubation with radioactive calcium, activity was found in the erythrocyte membranes. Calcium binding could be reduced by prior treatment of the erythrocyte with EDTA, neuraminidase, and to a lesser extent, by papain and trypsin. Other enzymes had no demonstrable effect. Stored erythrocytes showed a progressive diminution in calcium binding over a period of up to 4 weeks.

Binding Sites↗
PubMed1978

Ultrastructural study of normal and leukaemic leucocyte processes.

Cellular processes of leucocytes from both normal and leukaemic subjects were studied at the ultrastructural level. By high voltage transmission electron microscopy without a metal coating, more surface features could be seen in the cells than were observed by either scanning electron microscopy or conventional transmission electron microscopy. The technique was shown to be especially useful as it allows direct visualisation of the cell surface structure at high resolution without artefact-inducing preparative processes. Demonstrating receptor sites with this technique opens up the possibility of studying lymphocyte microvilli in greater detail.

Binding Sites↗
PubMed1976

Intercellular contacts between erythroid precursors in the bone marrow in dyserythropoiesis.

The ultrastructure of the cellular interfaces between erythroid precursors has been studied in both congenital and acquired dyserythropoiesis. The types of cell-to-cell contacts found included highly convoluated interdigitating septate-like junctions as well as apparent confluence of the cellular membranes of adjacent erythroid cells. Such findings are not characteristic of the intercellular relationships found in the normal erythroblastic islands. The erythroid plasma membrane modifications are possibly related to the changes in the plasma membranes of erythroid cells known to occur in dyserythropoiesis and their presence may well contribute to the ineffective erythropoiesis with intramedullary cell destruction which characterizes many dyserythropoietic states.

Bone Marrow↗
PubMed1975

The ultrastructure of dyserythropoiesis in aplastic anaemia.

Electron microscopy of erythropoiesis in aplastic anaemia has demonstrated some unique features of dyserythropoiesis at the ultrastructural level, which contribute to understanding of the morphological features which are seen in the light microscope. The findings provide further evidence for the presence of qualitative defects in erythropoiesis in aplastic conditions. The alterations seen included bi- and multinucleated cells, intercellular bridges containing microtubules, internuclear chromatin bridges, irregular nuclear shapes, juxta-nuclear and peripheral cisternal structures, ringed sideroblasts, a diversity of intranuclear inclusions, nuclear clefts in both eu- and heterochromatin, and a variety of anomalies of the nuclear membrane. The significance of the occurrence of these anomalies in aplastic anaemia is considered and the role of the nuclear membrane and of endoplasmic reticulum in the pathogenesis of aplastic anaemia is discussed.

Adult↗
PubMed1975

A transmission electron microscope study of the effects of ion etching on cells.

The effects of ion etching on blood cells have previously been studied by scanning electron microscopy. This present study by transmission electron microscopy was undertaken to evaluate the effects of the etching process on the cells. Critical point dried preparations were made, etched and subsequently processed and embedded in Araldite. Examination of thin sections of erythrocytes revealed disintegration of the plasma membrane; the residual membrane destruction products formed the tips of cones produced by long etching times. The effect of etching varied in erythrocytes in the same preparation. Nucleated cells showed a similar disintegration of the plasma membrane, but membranes of mitochondria, granules, vesicles and vacuoles did not exhibit effects of etching comparable to those of the plasma membranes. After treatment with a number of different fixatives, erythrocytes on carbon-coated copper grids were also etched and examined directly in a high voltage electron microscope at 1 MV. The effects were comparable to those seen in thin sections. To study the etch rates of biological materials, the resonant frequencies of quartz crystals were measured after application of thin films of albumen and cholesterol and again after these had been etched. the ratio of the frequency changes indicated that the etch rate of albumen was approximately 2-5 times that of cholesterol. The results are discussed in the light of theories of the mechanisms involved in ion etching.

Cell Membrane↗