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Biomedical subjects

G Cohnen

Publications and source records attributed to G Cohnen.

At least 19 recordsLinked to original sources
PubMed1977

Scanning electron microscopic study of leukemic human B lymphocytes.

Peripheral blood lymphocytes from patients with chronic lymphocytic leukemia (CLL), lymphoplasmacytoid lymphoma, centrocytic lymphoma and hairy cell leukemia were studied by scanning electron microscopy (SEM). In general, SEM revealed rather homogenous cell populations. Most lymphocytes displayed a moderately villous surface architecture, although smooth surfaces predominated in 3 cases with CLL and in 1 case with lymphoplasmacytoid lymphoma. Hairy cells showed surface features of both lymphocytes and monocytes. The results indicate that leukemic B and T lymphocytes cannot be distinguished by SEM alone.

B-Lymphocytes↗
PubMed1976

[T-cells in thyroid disease (author's transl)].

Thymus-derived peripheral blood lymphocytes were studied in untreated (n = 18), methimazole-treated (n = 28) thyrotoxicosis, after radioiodine (n = 14), in Hashimoto thyroiditis (n = 7) and in euthyroid goiter (n = 7). The results were compared with normal persons (n = 40) without thyroid disease. There was no significant difference in the total and relative counts of T-cells either between the different groups nor compared with the controls. These findings confirm that T-cells in peripheral blood cannot give any information about activity or prognosis of the various thyroid diseases. Thus T-cells give no further suggestion concerning the possible pathogenetic role of cell-mediated-immunity.

Goiter↗
PubMed1976

[Transitory monoclonal gammaopathy after smallpox vaccination].

The case is described of a 51-year-old female who developed monoclonal gammopathy of IgMk-type following smallpox vaccination. The Mcomponent was detectable, albeit in decreasing concentrations, over a period of 10 months and then disappeared spontaneously. The findings are discussed in relation to "essential" paraproteinemia and the literature on transient monoclonal gammopathy is reviewed. This immunoglobulin abnormality may occur in a variety of disorders and has mainly been observed during infectious or inflammatory processes.

Female↗
PubMed1976

Distribution of erythrocyte receptors at the surface membrane of human T-lymphocytes.

During incubation at 4 degrees C, the binding sites for neuraminidase-treated human erythrocytes (nHRBC) and sheep red blood cells (SRBC) were diffusely distributed on the surface membrane of most rosette-forming normal human blood lymphocytes. Increasing the temperature to 37 degrees C resulted in a rapid rosette dissociation which was accompanied by a relative increase in cap formation and a corresponding decrease of ring-like rosettes. The conversion into caps was inhibited by reincubation of the cells at 4 degrees C. The results indicate a movement of the nHRBC and SRBC receptors in the plane of the human T lymphocyte plasma membrane.

Binding Sites↗
PubMed1976

Cell numbers in human lymphocyte cultures stimulated with pokeweed mitogen.

As determined by electronic cell counting, the cell numbers in pokeweed mitogen (PWM) stimulated cultures of normal lymphocytes decreased by about 13% during the first day and then remained almost constant up to day 8. In contrast, a progressive decrease of the cell count was observed in cultures of chronic lymphocytic leukaemia (CLL) lymphocytes reaching about 40% of the initial number on day 8. In PWM cultures of normal lymphocytes the transformed cells increased to about 20% of the cells present on day 4, whereas in cultures of CLL lymphocytes these cells reached only 11% on day 7.

B-Lymphocytes↗
PubMed1975

Studies on human T lymphocyte rosette formation with human and sheep erythrocytes.

A large proportion of normal human blood lymphocytes forms rosettes with neuraminidase-treated autologous and allogeneic human erythrocytes (nHRBC) or sheep red blood cells (SRBC). In contrast, the percentage of rosette-forming cells is extremely reduced in the peripheral blood of patients with chronic lymphocytic leukemia. The formation of mixed rosettes after addition of nHRBC and SRBC suggests that most normal rosette-forming lymphocytes have receptor sites for both types of erythrocytes. Rosette formation with neuraminidase-untreated HRBC occurs only with a small fraction of normal lymphocytes, but can be increased by preincubating the lymphocytes with neuraminidase. Similar to rosette formation with SRBC. the binding of nHRBC is temperature-dependent, is prevented by pretreatment of the lymphocytes with proteolytic enzymes, but is not inhibited by EDTA. Rosette dissociation during incubation at 37 degree C is accompanied by conversion of ring- or morula-like rosettes into horseshoes or caps.

Animals↗
PubMed1975

[Lymphocyte in chronic lymphatic leukemia].

In patients with chronic lymphatic leukemia (CLL) the majority of peripheral blood lymphocytes was characterized as B cells by surface membrane markers. Ultrastructural studies revealed a reduction of the cytoplasmic area. Furthermore, the number of lysosomes was diminished corresponding to a decreased activity of lysosomal hydrolases. Increasing blood lymphocytosis was paralleled by an increase of the percentage of lysosome-poor lymphocytes. Response of CLL lymphocytes to in vitro stimulation with PHA and PWM was either lacking or diminished and/or delayed, and the number of transformed cells was reduced. Thus, the majority of CLL lymphocytes appears to represent both morphologically and functionally abnormal neoplastic b cells. During the early and later phase of stimulation the mitogen-reactive CLL lymphocytes exhibited alterations of the lysosomal apparatus similar to those observed in normal cells. The reactive lymphocytes may be derived from residual populations of normally functioning T and/or B cells. However, the neoplastic cells may also be able to respond to the mitogens. In vivo studies showed impaired kinetics of circulation and recirculation of CLL B lymphocytes, whereas the T cells were normal in this respect.

B-Lymphocytes↗
PubMed1975

Human T-lymphocyte rosette formation: inhibition by cytochalasin B.

The effects of cytochalasin B, colchicine and vinblastine on the rosette formation of human T lymphocytes with neuraminidase-treated human erythrocytes (nHRBC) and with sheep red blood cells (SRBC) have been studied. Pretreatment of the lymphocytes with cytochalasin B which affects microfilament action reversibly inhibits both nHRBC and SRBC rosette formation. Colchicine and vinblastine known to interact with microtubules causes no major reduction in rosette-forming cells. The results suggest that normally functioning microfilaments are necessary for nHRBC and SRBC rosetting, whereas microtubules are not essential for the blinding of the erythrocytes to the lymphocytes.

Colchicine↗