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Biomedical subjects

K Siegler

Publications and source records attributed to K Siegler.

6 recordsLinked to original sources
PubMed2001

Cytokine manipulation of explanted Dupuytren's affected human palmar fascia.

INTRODUCTION: Dupuytren's disease plagues human hands and digits producing fibrotic nodules and fascial cords with resultant debilitating flexion contracture deformities. Interest in this condition is great but because the disease is specific to humans and study has been hampered by the lack of an in vivo model. By utilizing an in vivo "nude" rat model it is possible to maintain and study explanted Dupuytren's contracted palmar fascia for prolonged periods of time. MATERIALS AND METHODS: Human specimens were divided into four, one for in vitro analysis, and three for model explantation. The explanted tissue was perfused with either transforming growth factor beta-2 (TGFbeta2), its antibody, or a control vehicle. Explant biopsies were obtained at 30 and 60 days and compared to tissue prior to explantation. Immunohistochemistry of collagen I and III, DNA synthesis, protein production, and fibroblast kinetics were serially determined. RESULTS: Perfusion of explanted Dupuytren's tissue by TGFbeta2 upregulated collagen I and III from biopsies obtained from the explants at 30 days when compared to vehicle control (P < 0.001). Perfusion with antibody prevented this upregulation when compared to vehicle control (P < 0.001). Cell cultures derived from fibroblasts obtained from biopsies of the explants perfused with TGFbeta2 increased DNA synthesis, protein production and fibroblast kinetics. CONCLUSION: These findings paralleled those from other fibroproliferative disorders suggesting a role for TGFbeta2 in the pathogenesis of Dupuytren's contracture as well as possible novel treatment approaches.

Analysis of Variance↗
PubMed1988

Thrombospondin promotes platelet aggregation.

Thrombospondin (TSP), isolated from human platelets, promotes aggregation of both nonstimulated platelets and platelets stimulated with thrombin or ADP. The TSP-promoted aggregation is specific since a monoclonal antibody against TSP inhibits the effect of exogenously added TSP and inhibits thrombin-induced platelet aggregation in the absence of added TSP. Several lines of evidence suggest that TSP mediates its effect on aggregation of nonstimulated and stimulated platelets through different platelet-surface receptor systems. The TSP-promoted aggregation of nonstimulated platelets was inhibited by a monoclonal antibody to platelet glycoprotein IV (GPIV), but not by a monoclonal antibody to the fibrinogen receptor, GPIIb-IIIa. In contrast, the antibody to GPIIb-IIIa totally inhibited the TSP-potentiated aggregation of thrombin-stimulated platelets, whereas the antibody to GPIV has no effect. Thus, these studies suggest that TSP promotes platelet aggregation by at least two mechanisms--one dependent on and one independent of the platelet fibrinogen receptor system.

Adenosine Diphosphate↗
PubMed1987

Thrombospondin promotes cell-substratum adhesion.

The physiological role of the platelet-secreted protein thrombospondin (TSP) is poorly understood, although it has been postulated to be involved in platelet aggregation and cellular adhesion. In this report, TSP isolated from human platelets was found to promote, in vitro, the cell-substratum adhesion of a variety of cells, including platelets, melanoma cells, muscle cells, endothelial cells, fibroblasts, and epithelial cells. The adhesion-promoting activity of TSP was species independent, specific, and not due to contamination by fibronectin, vitronectin, laminin, or platelet factor 4. The cell surface receptor for TSP is protein in nature and appears distinct from that for fibronectin.

Animals↗
PubMed1981

[Determination of glucoamylase activity using an enzyme electrode].

Both, the differing definitions of glucoamylase activity and the different determination of the fragment, glucose, preclude a comparison of literature data. Specific enzymatic determination of the fragment, glucose, with an enzyme electrode is proposed. The contribution describes the manufacture of an enzyme electrode from a commercial pO2-electrode and immobilized GOD. The measurement may be carried out by kinetic determination of utilized oxygen or oxygen peroxide formed. The continuous measurement proposed for serial experiments is made via a calibration curve, whose regression coefficient was determined to be 0.999. Depending on the enzyme activity, the reaction time is between 15 s and 3 min.

Electrodes↗