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Biomedical subjects

R L Nachman

Publications and source records attributed to R L Nachman.

At least 109 records · Page 6Linked to original sources
PubMed1976

A clinical study of the lupus anticoagulant.

Eighty-three patients with circulating anticoagulants were studied at The New York Hospital. The lupus-type anticoagulant, an inhibitor of the prothrombin activator complex, was demonstrated in 58 patients. The inhibitor was identified using the blood and tissue thromboplastin inhibition tests. Inhibition by the lupus anticoagulant was augmented in 67% of these patients by a cofactor present in normal plasma. The lupus inhibitor was detected primarily because of an unsuspected abnormal coagulation test. One-half of the patients with the lupus-type anticoagulant did not have systemic lupus erythematosus.

Anticoagulants↗
PubMed1975

Ultrastructural lesions on the surface of platelets associated with either blood coagulation or with antibody-mediated immune injury.

During blood coagulation ultrastructural lesions were produced on the platelet membrane. They were dependent on the presence of both thrombin and complement (C) and were morphologically identical to the C-dependent ultrastructural lesions (type II) seen in red cells subsequent to activation of C by the alternate mechanismmthough similar in shape they differed in size from ultrastructural lesions (type I) PRODUCED BY ACTIVATION OF C via the classic mechanismmlesions of type I were seen on the platelet surface subsequent to antibody-dependent activation of the C system.

Aluminum Hydroxide↗
PubMed1975

Subcellular platelet factor VIII antigen and von Willebrand factor.

Subcellular membrane and granule fractions derived from human platelets contain factor VIIII antigen and von Willebrand factor activity but not factor VII procoagulant activity. Circulating platelets constitute a significant reservoir of plasma factor VIII antigen, containing approximately 15% of the amount of factor VIII antigen present in platelet-poor plasma. The antibiotic ristocetin, which aggregates human platelets in the presence of von Willebrand factor, nonspecifically precipitates platelet membrane factor VIII antigen. Thus normal platelets contain surface-bound as well as internally stored von Willebrand factor, a protein synthesized by endothelial cells which is necessary for normal platelet function in vivo.

Absorption↗
PubMed1975

Subunit structure of factor VIII antigen synthesized by cultured human endothelial cells.

Cultured human endothelial cells were labeled with (3H)leucine, and the radioactive Factor VIII antigen present in the postculture medium was isolated by double anitbody immunoprecipitation and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after reduction with dithiothreitol. The Factor VIII antigen synthesized by cultured endothelial cells was found to contain the same single polypeptide subunit (mol wt 225,000) present in plasma Factor VIII antigen. These results suggest that in vivo, the endothelial cell is a major site of synthesis of circulating Factor VIII antigen.

Antigens↗
PubMed1974

Synthesis of von Willebrand factor by cultured human endothelial cells.

Cultured human endothelial cells synthesize and secrete a protein(s) which has Factor VIII antigen but which lacks Factor VIII clot-promoting activity (J. Clin. Invest. 52, 2757-2764, 1973). Von Willebrand factor activity has been identified in medium from cultured human endothelial cells. This activity was demonstrated by the ability to correct the defect in platelet adhesiveness of blood obtained from patients with von Willebrand's disease. This activity also supported ristocetin-induced aggregation of washed normal human platelets. The von Willebrand factor activity from cultured endothelial cells has physicochemical and immunologic properties like those of the von Willebrand factor activity and the Factor VIII antigen present in human plasma and the Factor VIII antigen synthesized by human endothelial cells in vitro. Rabbit antibody to chromatographic fractions containing endothelial cell von Willebrand factor inhibits the platelet retention of normal blood in glass bead columns.

Animals↗
PubMed1973

Culture of human endothelial cells derived from umbilical veins. Identification by morphologic and immunologic criteria.

Endothelial cells were isolated from freshly obtained human umbilical cords by collagenase digestion of the interior of the umbilical vein. The cells were grown in tissue culture as a homogeneous population for periods up to 5 mo and some lines were subcultured for 10 serial passages. During the logarithmic phase of cell growth, cell-doubling time was 92 h. Light, phase contrast, and scanning electron microscopy demonstrated that cultured human endothelial cells grew as monolayers of closely opposed, polygonal large cells whereas both cultured human fibroblasts and human smooth muscle cells grew as overlapping layers of parallel arrays of slender, spindle-shaped cells. By transmission electron microscopy, cultured endothelial cells were seen to contain cytoplasmic inclusions (Weibel-Palade bodies) characteristic of in situ endothelial cells. These inclusions were also found in endothelial cells lining umbilical veins but were not seen in smooth muscle cells or fibroblasts in culture or in situ. Cultured endothelial cells contained abundant quantities of smooth muscle actomyosin. Cultured endothelial cells also contained ABH antigens appropriate to the tissue donor's blood type; these antigens were not detectable on cultured smooth muscle cells or fibroblasts. These studies demonstrate that it is possible to culture morphologically and immunologically identifiable human endothelial cells for periods up to 5 mo.

ABO Blood-Group System↗
PubMed1973

Synthesis of antihemophilic factor antigen by cultured human endothelial cells.

Antihemophilic factor (AHF, Factor VIII) antigen has been demonstrated in cultured human endothelial cells by immunofluorescence studies using monospecific rabbit antibody to human AHF. Control studies with cultured human smooth muscle cells and human fibroblasts were negative. By radioimmunoassay it was demonstrated that cultured human endothelial cells contain AHF antigen which is released into the culture medium. Cultured smooth muscle cells and fibroblasts did not have this property. Cultured endothelial cells incorporated radioactive amino acids into high molecular weight, AHF antigen-rich protein fractions prepared from the culture media, 7% of the radioactive amino acid counts incorporated into this material were precipitated by globulin prepared from rabbit anti-AHF whereas normal rabbit globulin precipitated only 1.5% of the counts. Although cultured endothelial cells actively synthesize AHF antigen, AHF procoagulant activity was not detected in the culture medium. Studies seeking a basis for the lack of procoagulant activity have not clarified this deficiency, but they have established that exogenous AHF procoagulant activity is not inactivated by the tissue culture system.

Animals↗
PubMed1973

Contractile proteins of endothelial cells, platelets and smooth muscle.

In experiments described herein it was observed, by direct and indirect immunofluorescence technics, that rabbit antisera to human platelet actomyosin (thrombosthenin) stained mature megakaryocytes, blood platelets, endothelial cells and smooth muscle cells of arteries and veins, endothelial cells of liver sinusoids and certain capillaries, uterine smooth muscle cells, myoepithelial cells, perineurial cells of peripheral nerves and "fibroblastic" cells of granulation tissue. The specificity of immunohistologic staining was confirmed by appropriate absorption and blocking studies and immunodiffusional analysis in agarose gel. It was also observed by immunodiffusional analysis in agarose gel, electrophoresis of actomyosin fragments in polyacrylamide gels, immune inhibition of actomyosin ATPase activity and immune aggregation of platelets that uterine and platelet actomyosin are partially, but not completely, identical.

Actomyosin↗
PubMed1972

Characterization of human platelet vascular permeability-enhancing activity.

Human platelet acid extract obtained from both whole platelets and from isolated subcellular granules was partially purified by DEAE-cellulose chromatography and Sephadex gel filtration. The heat-stable, nondialyzable cationic protein fraction with a mol wt of approximately 30,000 produced a biphasic increase in vascular permeability in rabbit skin and also had antiheparin activity. The acute (15 min) increase in vascular permeability was blocked by prior treatment of the animal with antihistamine and was characterized histologically by edema of perivascular tissues and dilation of capillaries and veinules. The delayed (3 hr) permeability effect was not blocked by antihistamine and was characterized histologically by leukocytic infiltration into the skin. The experiments described suggest that human platelet lysosomal release of cationic proteins may increase vascular permeability by several mechanisms including endogenous histamine release as well as delayed chemotaxis.

Animals↗