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Biomedical subjects

H Bessler

Publications and source records attributed to H Bessler.

At least 109 records · Page 6Linked to original sources
PubMed1980

Beneficial effect of chloramphenicol on pyrexia in patients with acute leukemia.

6 patients with acute leukemia are described. All of them suffered from high temperature and malaise, and showed negative urine and blood cultures. High doses of gentamicin, cephalothin and cerebenicillin failed to lower the fever. The temperature became normal after administration of chloramphenicol (CAP) 2.0 g/day. In 3 out of 6 patients the peripheral blood blast cell count decreased following CAP administration. Incubation of acute lymphoblastic leukemia cells with CAP in vitro showed a marked decrease in the DNA synthesizing activity of the leukemic cells. The role of CAP as an additional tool in the treatment of acute leukemia is discussed.

Adolescent↗
PubMed1980

Quantitative determination of human plasma erythropoietin using embryonic mouse liver erythroblasts.

An in vitro bioassay for the quantitative detection of erythropoietin (Ep) in human plasma is described. The method is based on the increased 3H-uridine incorporation into 12-day embryonic mouse liver erythroblasts due to Ep. It was found that 11 out of 12 anaemic patients showed high plasma Ep level, while 7 out of 8 patients suffering from polycythaemia revealed low Ep values. In 4 out of 8 patients with chronic renal failure the Ep level was within the normal range, whereas in the remaining 4 it was higher than normal. The relative simplicity of the method and the reproducibility of the results make it useful even in the routine laboratory.

Anemia↗
PubMed1980

Lectin-like effect of Echis coloratus Venom on human and mouse lymphocytes.

Echis coloratus venom (ECV) treated human and mouse lymphocytes were examined for synthesizing activities and morphologic alterations. RNA, DNA and protein synthesis were markedly inhibited. Human cells were less affected than mouse lymphocytes. No mitogenic activity was observed. Transmission (TEM) and scanning electron microscopy (SEM) revealed membranal damage in all types of lymphocytes and a considerable degree of agglutination. Human lymphocytes showed concentration of the microvilli at one pole of the cell. This phenomenon was considered as a capping effect. The action of ECV may be compared with the effect of the nonmitogenic lectin RCAII, known to penetrate the cells by endocytosis and to inhibit their protein synthesis.

Animals↗
PubMed1980

The effect of parathyroid hormone (PTH) and 1,25 dihydroxy vitamin D3 (1,25(OH)2D3) on RNA and heme synthesis by erythroid precursors.

PTH was shown to stimulate RNA and heme synthesis in 12-13 days embryonic mouse liver erythroid cells, thus expressing an erythropoietin-like effect. Incubation of erythroid precursors with 1,25(OH)2D3 had no effect on heme synthesis, and increased the RNA synthesis only slightly, thus showing no enhancement effect of 1,25(OH)2D3 on the PTH stimulating effect on erythropoiesis.

Animals↗
PubMed1980

Two T lymphocyte subpopulations isolated from human peripheral blood following "in vitro" treatment with adenosine.

Incubation of human peripheral blood lymphocytes (PBL) with adenosine resulted in a decrease in the level of E-rosette forming cells (ERFC). Isolated ERFC rerosetted with sheep erythrocytes in the presence of adenosine yielded two T lymphocyte subpopulations: a major one, rosetting or "E(R)" and a minor one, non-rosetting or "E(S)" T cells. Characterization of the two isolated subpopulations revealed that both E(R) and E(S) cells were positive for human T lymphocyte antigen. However, in contrast to E(R) cells, E(S) cells had low rosetting capacity, high spontaneous thymidine incorporation and low PHA proliferative response.

Adenine↗
PubMed1979

SEM observations on the mechanism of platelet release from megakaryocytes.

Normal human bone marrow megakaryocytes were examined with the scanning electron microscope (SEM) to clarify the mechanism of platelet release. Several types of megakaryocytes were dtected according to their surface appearance, i.e. with wrinkles, ridges, villous formations, round blebs and cells with platelets still attached to the cell membrane. These observations are consistent with the concept that bleb formation is at least one of the mechanisms for platelet liberation.

Blood Platelets↗
PubMed1979

pH-induced platelet ultrastructural alterations. A possible mechanism for impaired platelet aggregation.

After the observation that lavages with alkaline solutions exert a beneficial effect on the bleeding tendency and increase platelet aggregation in patients with intragastric hemorrhage, studies were undertaken to find a relationship between changes of pH and platelet morphology. Transmission and scanning electron microscopy showed that at a pH lower than 7.4, normal human platelets change their internal structure as well as their shape, becoming spheres deprived of pseudopodia. On the other hand, a pH higher than 7.4 induces transformation of platelet internal organelles similar to that caused by thrombin. At an alkaline pH, the platelets develop multiple pseudopodia that facilitate their attachment to each other. These findings may explain the increased platelet aggregation in alkaline medium demonstrated in one of our previous works.

Blood Platelets↗
PubMed1979

The surface ultrastructure of Gaucher cells.

The Gaucher cells of seven patients with Gaucher's disease were examined by both transmission and scanning electron microscopy. The ultrastructure of the cells, as seen by transmission electron microscopy, did not differ from that reported in the literature. The surface structure varied not only in the different patients but also in the same individual. The cells were oval or round, most of them with a rough surface due to presence of microvilli, ruffles, ridges, and blebs of various numbers and shapes. In two patients the Gaucher cells showed phagocytosis. The appearance of the surface ultrastructure of the Gaucher cells supports the accepted view that they are related to the cells of the reticuloendothelial system.

Adolescent↗
PubMed1979

Increased RNA and heme synthesis in mouse erythroid precursors by parathyroid hormone.

The in vitro effect of parathyroid hormone (PTH) on RNA and heme synthesis by embryonic mouse liver erythroid precursors was examined. PTH produced a dose-dependent effect on RNA synthesis. A maximal increase of 60 +/- 16% (p less than 0.02) was observed with 1.0 U PTH/ml, whereas with higher concentrations a significant decline was found. Furthermore, PTH stimulated heme synthesis after 24 h of incubation. The maximal enhancement of 32 +/- 7% (p less than 0.01) was observed with 0.5 U PTH/ml, a lower effect was obtained with 1.0 U PTH/ml, while 2.0 U PTH/ml caused a pronounced decrease of heme synthesis. These data indicate that PTH affects directly the erythroid precursors by a mechanism similar to that of erythropoietin. The inhibitory effect on the RNA synthesis observed with large doses of PTH may explain at least one of the causes of the anemia reported in patients with primary hyperparathyroidism.

Animals↗
PubMed1979

The role of hemin in the regulation of heme synthesis by fetal mouse liver erythroblasts in culture.

The regulatory role of exogenous hemin on the heme synthetic pathway was studied in fetal mouse liver erythroblasts in culture. Hemin added to culture medium of 13th day embryo liver cells inhibited, dose dependently, the incorporation of the porphyrin precursors, 59Fe, 14C-2-glycine and 14C-5-aminolevulinic acid (ALA) by 85%, 70% and 45%, respectively. This suggests a multiple effect of hemin on the porphyrin biosynthetic enzymes. Exogenous ALA competed with 14 C-2-glycine as a porphyrin precursor, but the rate of heme synthesis, measured by 59Fe incorporation, remained unaltered. Protoporphyrin mimicked the hemin effect on the inhibition of glycine incorporation into heme, but reduced iron incorporation by only 20%. Erythroblasts, with an inhibited porphyrin biosynthesis, utilized exogenous 59Fe-hemin for hemoglobin assembly and maintained an undecreased level of hemoglobin synthesis. The results indicate that hemin inhibits the porphyrin biosynthesis in fetal mouse liver erythroblasts mainly at the iron incorporation stage.

Aminolevulinic Acid↗
PubMed1978

Effect of prostaglandin A2 on RNA synthesis in embrionic mouse erythroid cells.

Prostaglandin A2 (PGA2) is shown to stimulate RNA synthesis in 12-day embryonic mouse liver cells, thus expressing an erythropoietin-like effect. This effect was found to be dose-dependent. There was no significant difference between the results observed with patients' plasma before and after dialysis and with or without addition of PGA2. Although the baseline activity of RNA synthesis in the presence of uremic plasma is less than that with normal plasma, the almost equal potentiation of RNA synthesis in erythroid cells incubated with both normal and uremic plasma obtained with PGA2 favors a direct, and not an erythropoietin-mediated, effect of this substance.

Animals↗
PubMed1978

SEM observations on Sendai virus-induced fusion of embryonic mouse erythroblasts.

The events of fusion of 11- and 16-day embryonic mouse liver erythroblasts induced by Sendai virus (SV) were followed with the scanning electron microscope (SEM). Erythroid precursors incubated with the virus showed numerous 'pores' on the cell membrane. The cell fusion began with the appearance of a fine 'meshwork' structure between the adjacent cells, followed by a gradual formation of a common cell membrane and terminated with the appearance of polykaryons, in which the nuclei were easily recognized when located in the vicinity of the polykaryon membrane. There was no difference in the process of fusion between erythroblasts at identical and those at different stages of maturation.

Animals↗
PubMed1978

Role of the spleen and lymphocytes in regulation of the circulating platelet number in mice.

The role of the spleen in the regulation of the circulating platelet number was studied in mice. The increased 75Se-Met incorporation found after removal of the spleen indicates that postsplenectomy thrombocytosis is due to enhanced platelet production. The increased thrombopoietic activity observed in the plasma of splenectomized mice proves the presence of a humoral factor which mediates this process. Administration of spleen lymphocytes to control mice caused mild thrombocytopenia and prevented postsplenectomy thrombocytosis in splenectomized animals. Moreover, culture medium obtained from peripheral blood and spleen lymphocytes contained a substance which induces thrombocytopenia when injected into control mice. The mechanism by which the spleen and lymphocytes affect the amount of circulating platelets is discussed.

Animals↗
PubMed1977

Erythroid precursor fusion induced by Sendai virus.

The ultrastructural events of the interaction of Sendai virus (SV) with fetal mouse erythroid precursors, and SV-induced fusion of erythroid precursors at different maturation stages are described. SV was shown to affect the erythroid nuclei causing interruption of the nuclear membrane, enlargement of the nucleolus and nuclear fusion. SV induced fusion also between dividing and non-dividing cells.

Animals↗