PubMed Health⌕ Search

Biomedical subjects

S G Quan

Publications and source records attributed to S G Quan.

27 records · Page 2Linked to original sources
PubMed1978

Trimethoprim and sulphamethoxazole inhibition of haematopoiesis in vitro.

The effect of trimethoprim and sulphamethoxazole on haematopoiesis was studied in vitro using cloning techniques for human and murine erythroid and granulocytic precursor cells. Trimethoprim was found to inhibit granulopoiesis and erythropoiesis in vitro in a dose-dependent fashion with approximately 50% inhibition of human erythroid and granulocytic colonies at a therapeutically achievable concentration of 7 micrograms/ml. Sulphamethoxazole was also shown to impair haematopoiesis in vitro. The inhibition caused by both these constituents of co-trimoxazole was completely reversed by folinic acid. The data suggest that co-trimoxazole can impair human haematopoiesis by inhibition of tetrahydrofolate synthesis. These observations suggest that the clinical haematopoietic toxicity of trimethoprim-sulphamethoxazole can be abrogated by simultaneous administration of folinic acid.

Adult↗
PubMed1978

Human T lymphocyte cell line producing colony-stimulating activity.

We derived a permanent human T lymphocyte cell line that elaborates a potent colony-stimulating activity (CSA). The line was established with spleen cells from a patient with a T lymphocyte variant of hairy-cell leukemia. These cells form rosettes with sheep erythrocytes, show a proliferative response to phytohemagglutinin, and are lysed by antithymocyte globulin. They do not synthesize immunoglobulin, nor do they contain Epstein-Barr virus. CSA is regularly detected in the supernatant medium after 3 days culture. In the presence of PHA there is augmented elaboration of CSA; maximal activity is reached by 2 days and is 20% greater than that produced by a feeder layer of 1 X 10(6) peripheral blood leukocytes. One microliter of the supernatant material stimulated colony formation from the light-density nonadherent fraction of human bone marrow; there was maximal activity between 10 and 50 microliter/ml. Conditioned medium from these cells has little effect in stimulating CFU-C from murine bone marrow. The availability of a human T lymphocyte line producing CSA will provide a source for large quantities of the lymphocyte-derived hormone and permit a definition of factors modulating the interaction of T lymphocytes with granulocyte and monocyte stem cells.

Cell Line↗
PubMed1978

Immunologic characterization of hairy cell leukemias in continuous culture.

The immunobiologic characteristics of three continuous cell lines established from hairy cell leukemia cells were investigated. All three cell lines continued to produce tartrate-resistant acid phosphatase, the enzymatic marker of hairy cells. Two of these cell lines were B lymphoid in nature. They carried Fc and C receptors, had surface and internal immunoglobulin, and did not form spontaneous sheep red blood cell rosettes. Experiments employing biosynthetic radiolabeling of immunoglobulin demonstrated distinctive immunoglobulin kinetics for each of these two hairy cell lines. One cell line remained quite similar to the original hairy cells from which it was derived whereas the other B lymphoid hairy cell line had undergone a switch in the immunoglobulin isotype produced. The third hairy cell leukemia line was shown to be of thymic derivation. These cells formed spontaneous sheep red blood cell rosettes and did not carry Fc or C receptors. The spontaneous sheep red blood cell rosette-forming cells contained tartrate-resistant acid phosphatase. They did not possess surface on internal immunoglobulin and did not synthesize immunoglobulin in vitro. Hairy cell leukemia cells maintained in permanent cell culture retain their immunobiologic properties and offer the opportunity for indepth study of these unusual cells.

Acid Phosphatase↗
PubMed1977

Immunoglobulin synthesis in hairy cell leukaemia.

In vitro studies were performed with leukaemic cells from two patients with hairy cell leukaemia in order to define the nature and kinetics of immunoglobulin synthesis by the neoplastic cells. Both patients had clinically and morphologically well-defined disease and their cells contained abundant tartrate-resistant acid phosphatase. One patient had associated macroglobulinaemia. The hairy cells had B-lymphocyte characteristics as determined by fluorescent immunoglobulin staining and surface receptor properties. They synthesized monoclonal IgM and IgG respectively in vitro. The kinetics of immunoglobulin synthesis were different in cells from the two patients as measured by equilibration time, intracellular degradation, and secretion. Permanent cell lines were established with cells from these patients. The lines grow as typical B-lymphoblastoid cultures and continue to produce tartrate-resistant acid phosphatase and immunoglobulin. These studies unequivocally demonstrate the B-lymphocyte nature of the hairy cells in these patients and provide evidence for their clonal origin both in terms of immunoglobulin and enzyme synthesis.

Acid Phosphatase↗
PubMed1976

Inhibition of murine granulopoiesis in vitro by dexamethasone.

The effect of dexamethasone on mouse bone marrow granulocyte-monocyte precursor cells (CFU-C) was studied in vitro. Dexamethasone inhibited colony formation in the presence of maximally stimulating concentrations of colony-stimulating activity. A mean colony reduction of 55% occurred at 10(-9) M dexamethasone and inhibition was observed at concentrations as low as 10(-12)M. The dexamethasone suppression could be abrogated by progesterone. These studies provide evidence that the committed granulocyte-monocyte stem cell has a glucocorticoid receptor mechanism that when activated results in inhibition of cellular proliferation in vitro.

Agar↗