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Biomedical subjects

G Geuens

Publications and source records attributed to G Geuens.

27 records · Page 2Linked to original sources
PubMed1978

DL-2-Oxo-3-(2-mercaptoethyl)-5-phenylimidazolidine. A sulfhydryl metabolite of levamisole that interacts with microtubules.

DL-2-Oxo-3-(2-mercaptoethyl)-5-phenylimidazolidine (OMPI) a sulfhydryl metabolite of levamisole, unlike the parent compound, is shown to interfere with the morphological and functional integrity of microtubules in cultured cells at high concentrations (1.6-10(-4) M). Lower concentrations do not affect the cell morphology, viability or growth rate in any appreciable way. Both levamisole and OMPI, at low concentrations (10(-5)-10(-6) m), markedly enhance the antimicrotubular effect of mercaptoethanol. High concentrations of OMPI (+/- 10(-4) M) inhibit the self-assembly of microtubules in a cell free system. Low concentrations (+/- 10(-6) M) markedly enhance the polymerization rate of tubulin. Levamisole has no effect on tubulin polymerization. The effects of OMPI on microtubules in cells and in the polymerization system can be reversed by reduced glutathione, cysteine and dithiothreitol. The data indicate that OMPI interacts in a biphasic manner with microtubule formation probably through interaction with critical SH-groups on the tubulin molecule. It seems of interest to further investigate the hypothesis that the immunomodulating properties of levamisole are at least partially due to the formation of its metabolite (OMPI) which could enhance microtubule integrity and function in leukocytes.

Cells, Cultured↗
PubMed1978

Evidence for unaltered structure and in vivo assembly of microtubules in transformed cells.

By using immunoperoxidase cytochemistry at the light and electron microscopic level, microtubles were visualized in a number of "normal" nontumorigenic and transformed tumorigenic cell lines. A well-defined cytoplasmic microtubule complex exists in both normal and transformed interphase cells. The distribution of this complex closely correlates with the cell shape and the degree of cell spreading. Our data support the idea that these properties determine the pattern of the cytoplasmic microtubule complex, rather than the reverse. Ultrastructural observations of immunoperoxidase-stained tumor cells showed characteristic microtubules in cells in which the microtubules were poorly resolved at the light microscopic level. The results suggest that microtubule assembly and structure are unaltered in transformed cells. However, this conclusion does not exclude the possibility that some of the microtubules' functions might be impaired in a yet-unknown way.

Cell Line↗
PubMed1978

Purine nucleoside phosphorylase in chronic lymphocytic leukemia (CLL).

Purine nucleoside phosphorylase (PNP), the enzyme schematically next to adenosine deaminase in the purine salvage pathway, has been demonstrated cytochemically in peripheral blood lymphocytes of healthy subjects and chronic lymphocytic leukemia (CLL) patients. The enzyme activity is confined to the cytosol. In healthy subjects the majority of lymphocytes are strongly reactive for PNP, whereas the rest are devoid of cytochemically demonstrable activity. The percentage of PNP-positive cells largely corresponds to the number of E rosette-forming cells and is inversely proportional to the number of Ig-bearing cells. In six of seven CLL patients studied only a minor percentage of the lymphocytes showed strong PNP activity, whereas the large majority (88%--98%) possessed trace activity. Such patients have a high number of Ig-bearing cells and a low number of E rosette-forming cells. A different pattern of markers was found in the lymphocytes of the seventh CLL patient: 66% were strongly reactive for PNP, an important number formed E rosettes, and a minor percentage were Ig bearing. These data indicate that PNP can be useful as a "nonmembrane" marker in the differentiation of the B and T cell origin in CLL and deserves to be studied in other lymphoproliferative disorders.

Histocytochemistry↗
PubMed1977

Purine nucleoside phosphorylase, a possible histochemical marker for T-cells in man.

A procedure is described for the histochemical detection of purine nucleoside phosphorylase (PNP) activity in circulating lymphocytes of man. The number of PNP-positive cells, as evaluated on smears of Ficoll--Hypaque purified cells, correlated well with the number of E-rosette-forming cells of the same blood samples of healthy and diseased people with normal or abnormal numbers of E-rosettes. In healthy people, the number of PNP-positive cells was within the range of 70-80% of the total lymphocyte population, whilst the corresponding E-rosette-forming cells were scored between 60-75%. Patients with unusually low or high E-rosettes had equally low or high numbers of PNP-reactive cells. More substantial evidence for the presence of PNP activity in T-cells and not in B cells was gathered from experiments in which PNP activity and surface membrane immunoglobulins (SMIg) were simultaneously demonstrated on the same preparation. These results showed, on the one hand, that the bulk of lymphocytes that are reactive for PNP do not reveal SMIg and, on the other hand, that most Ig-bearing cells were unreactive for PNP.

Histocytochemistry↗
PubMed1977

Ultrastructural immunocytochemical distribution of tubulin in cultured cells treated with microtubule inhibitors.

Microtubules in tissue cultured cells are stained immunocytochemically with the PAP-method using a purified antitubulin antibody. Treatment of the cells with microtubule inhibitors (colchicine, nocodazole, vinblastine) results in the disappearance of microtubules. The diffuse cytoplasmic staining is strongly increased in the cells by colchicine and nocodazole. Vinblastine produces paracrystalline aggregates that are strongly stained and macrotubules that are unstained. The diffuse staining is much less in vinblastine-treated cells. The bundles of intermediate filaments that are induced by all microtubule inhibitors do not bind the antitubulin antibody.

Benzimidazoles↗