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Biomedical subjects

C A Stevens

Publications and source records attributed to C A Stevens.

46 records · Page 3Linked to original sources
PubMed1982

The role of autologous helper and suppressor T cells in the regulation of human granulopoiesis.

Helper and suppressor T cells play a physiological role in immunoregulation and possibly in other biological systems. Previous studies have suggested that unfractionated T cells influence human blood cell formation in vitro. Subpopulations of such cells (TM and TG cells) were prepared by immune ox erythrocyte rosetting techniques. Co-cultures were established in semi-solid agar with autologous null lymphocytes as a source of granulocyte-macrophage progenitor cells (CFU-GM). TM(helper) cells produced an increase and TG (suppressor) cells a decrease in the expression of CFU-GM as reflected in the number of GM colonies generated by comparison with cultures of null lymphocytes alone. These data point to a contribution from T lymphocyte subpopulations to the physiological regulation of human granulopoiesis.

Cell Separation↗
PubMed1980

Elastase and lysozyme activities in human alveolar macrophages. Effects of cigarette smoking.

We compared the elastase and lysozyme activities of cells obtained by bronchoalveolar lavage from normal smokers and nonsmokers. After total and differential cell counts were obtained for the initial lavage cell population, we determined the enzyme activities of the total lavage cell population, the culture vessel's adherent alveolar macrophage cell fraction, and the cell culture supernatant medium. Our data indicated that macrophages, particularly from smokers, synthesized a calcium-dependent activity against a synthetic elastase substrate, succinyl-trialanine-p-nitroanilide. This activity was enhanced in smokers and was distinct from the polymorphonuclear leukocyte elastase as measured with this synthetic substrate. Measurements using insoluble elastin labeled with 3H demonstrated that smokers' macrophages also contained a serine-proteinase activity whose inhibitor profile resembled that of polymorphonuclear leukocyte elastase. Finally, macrophages from smokers secreted 5 times more lysozyme and contained more lactate dehydrogenase activity than did nonsmokers' macrophages. We suggest that pulmonary macrophages take up the polymorphonuclear leukocyte elastase and contain a synthetic substrate, "elastase". The biologic significance of this elastase activity is unclear. The enhanced lysozyme secretion by smokers' alveolar macrophages indicated increased biosynthetic activity by these cells.

Adult↗
PubMedDate not supplied

Collection of erythroid progenitor cells by cytapheresis of peripheral blood of normal donors.

Human peripheral blood may be an alternative to bone marrow as a source of cells for hemopoietic engraftment. The ability to collect large numbers of circulating granulocyte-macrophage progenitors provides support for this contention. In the present study of cells from normal granulocyte donors, the cell concentrates obtained by cytapheresis were shown to contain even greater numbers of primitive erythroid precursors (153-956 [median 647] per 10(6) mononuclear cells) than would be predicted from the peripheral blood mononuclear cell counts. Moreover, the number of primitive erythroid precursors harvested correlated significantly with the number of granulocyte-macrophage progenitors obtained and with the total lymphocyte collection. These observations further substantiate the validity of transplanting peripheral blood as hemopoietic tissue.

Cell Separation↗
PubMedDate not supplied

Analysis of locus heterogeneity in Waardenburg syndrome types 1 and 2 using highly informative microsatellite markers.

We performed linkage and locus heterogeneity analyses of Waardenburg syndrome (WS) types 1 and 2 using 9 DNA markers from 2q35-q37, including two highly polymorphic microsatellites very closely linked to the PAX3 candidate gene. None of 5 WS type 2 (WS2) families showed linkage to the PAX3 candidate region. We localized the marker D2S102 to less than 1 cM from PAX3 (lod = 33.7, theta = 0), but a complete absence of crossovers prevented determining whether it maps distal or proximal to PAX3. Study of 14 WS type 1 (WS1) families yielded a maximum lod score of 27.81 at PAX3, theta f = 0.010, theta = 0.007 assuming homogeneity. However, we found significant evidence of locus heterogeneity, with one family initially classified as WS1 unlinked to the PAX3 region. Reevaluation of the clinical features of this family revealed atypical morphology of inner canthi. This produced the appearance of dystopia canthorum and high W-index scores. While our one unlinked WS1 family exhibits atypical canthal morphology, our type 1 families with classic dystopia appear to be homogeneously linked to PAX3. These and other findings identify precautions that need to be addressed before using PAX3-linked markers for diagnostic purposes.

Chromosome Mapping↗