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Biomedical subjects

D F Mosher

Publications and source records attributed to D F Mosher.

At least 181 records · Page 10Linked to original sources
PubMed1981

Modification of shear modulus and creep compliance of fibrin clots by fibronectin.

Shear moduli and creep compliances have been measured for four types of clots of human fibrin (about 7 mg/ml) clotted with and without human plasma fibronectin (usually 1.2 mg/ml). Fine clots (with little lateral aggregation of the fibrin protofibrils) were found at pH 8.5, ionic strength 0.45; coarse clots (with substantial lateral aggregation) were formed at pH 7.5, ionic strength 0.15; in both cases with and without ligation by fibrinoligase. In fine clots, the addition of fibronectin without ligation scarcely affected the shear modulus; with ligation, the modulus was decreased by a factor of 0.48. In coarse clots, the shear modulus was increased by addition of fibronectin. The increase was by a factor of 2.0 without ligation and by a factor of 2.4 with ligation. Creep and creep recovery in clots formed with and without fibronectin were similar except for the scale factor represented by the change in modulus.

Animals↗
PubMed1981

Studies on the localization of the glycoprotein GP-2 within the renal glomerulus in vivo and in cultured kidney cell strains in vitro.

Positive staining for the glycoprotein GP-2 was demonstrated in the kidney glomerulus by use of the indirect peroxidase-labeled antibody technique. At the ultrastructural level, heaviest staining for GP-2 was demonstrated along the lamina rara externa and lamina rara interna of the glomerular and tubular basement membranes, demonstrating definite molecular organization for structures which appear amorphous even at the electron microscopic level. However, GP-2 was also present in the lamina densa of the glomerular basement membrane, but not of the tubular basement membrane. The staining for GP-2 is in contrast to the predominantly mesangial staining for fibronectin. Using the indirect immunoperoxidase techniques for kidney cells cultured in vitro, it was demonstrated that cell surfaces of specific subpopulations of glomerular cells stained heavily for both fibronectin and GP-2, while renal medullary cells did not stain at all using specific antiserum to these molecules. GP-2 was present extracellularly and showed moderate staining in glomerular cell culture, while fibronectin showed heavy staining in this location.

Animals↗
PubMed1981

Effect of blood transfusion on in vivo levels of plasma fibronectin.

Fibronectin, an opsonic glycoprotein, is known to bind fibrinogen and fibrin. Microaggregate debris contained in stored bank blood is composed of degenerating platelets, leukocytes, and fibrin strands. The debris ranges in size from 10 to 160 micrometers. This study examined the effect of transfusion of 2 units of stored red blood cells, containing varying amounts of macroaggregate debris, on in vivo levels of fibronectin. Anemic outpatients were selected at random to receive blood transfusion through either a 170 micrometer standard blood filter or one of four microaggregate filters. A sixth group received saline-washed red blood cells. Results showed that the greatest drop in posttransfusion levels of fibronectin (39 microgram/ml) were found in the group that received blood through a 170 micrometer standard filter and thus received the greatest amount of microaggregate debris (p less than 0.05; N = 50). The patients who received the least microaggregate debris, those receiving washed red cells, showed the smallest decrease in posttransfusion levels of fibronectin (9 microgram/ml); this decrease was not significant (p greater than 0.05; N = 50). Patients receiving blood through 20 to 25 micrometer microaggregate blood filters showed a fall in posttransfusion levels of fibronectin (10 to 15 microgram/ml) intermediate between that found for the two groups described above; this decrease was not significant (p greater than 0.05; N = 35). The decrease in posttransfusion levels of fibronectin found after administration of blood through a 40 micrometer microaggregate screen filter (31 microgram/ml) was significantly different from pretransfusion levels (p less than 0.05; N = 20). Data obtained from this study suggest that transfusion of the microaggregate debris contained in 2 units of stored bank blood can lower in vivo levels of fibronectin. We conclude that if maintaining high levels of fibronectin is shown to be of value in the treatment of critically ill patients, removal of microaggregate debris from any blood transfusions required by these patients would be warranted.

Adult↗
PubMed1980

Binding and factor XIIIa-mediated cross-linking of a 27-kilodalton fragment of fibronectin to Staphylococcus aureus.

A 27-kilodalton tryptic fragment, derived from the amino terminus of the 200-kilodalton fibronectin subunit, inhibited binding of intact fibronectin to Staphylococcus aureus and could be cross-linked to Staphylococcus aureus by blood coagulation Factor XIIIa. Interactions of fibronectin with Staphylococcus aureus via this fragment may be important for bacterial opsonization and attachment.

Amino Acid Sequence↗
PubMed1980

Binding and degradation of alpha 2-macroglobulin by cultured fibroblasts.

We studied the interactions of alpha 2-macroglobulin, a major protease inhibitor of plasma and of serum-containing culture medium, with cultured fibroblasts. Iodinated human alpha 2-macroglobulin bound specifically to washed cell layers of cultured human fibroblasts. At 0--4 degrees C, binding was saturated at a concentration of 10--20 micrograms/ml. At 37 degrees C, radiolabel appeared in the medium in a form soluble in 10% trichloroacetic acid. Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that ingested iodinated alpha 2-macroglobulin transiently forms a complex with a trypsin-like protease. Indirect immunofluorescence demonstrated alpha 2-macroglobulin in vacuoles of fibroblasts grown in 10% human serum or incubated with purified alpha 2-macroglobulin. Fibroblasts transformed by SV-40 (VA-13 cells) bound and degraded less 125I-labeled alpha 2-macroglobulin than non-transformed fibroblasts and had fewer vacuoles containing alpha 2-macroglobulin. These observations indicate that cultured fibroblasts bind, take up by endocytosis, and degrade alpha 2-macroglobulin. Binding and endocytosis of alpha 2-macroglobulin by a cell may be a means of modulating proteases in the microenvironment of the cell and during endocytosis.

Cell Transformation, Viral↗
PubMed1980

An axial periodic fibrillar arrangement of antigenic determinants for fibronectin and procollagen on ascorbate treated human fibroblasts.

Fibronectin and collagens are major constituents of the cell matrix of fibroblasts. Fibronectin is a 220,000 dalton glycoprotein that mediates a variety of adhesive functions of cells examined in vitro. Fibronectin is secreted in a soluble form and interacts with collagen to form extracellular filaments. Fibronectin and procollagen type I were localized using the peroxidase anti-peroxidase method. Under standard culture conditions, fibronectin and procollagen were localized to non-periodic 10 nm extracellular fibrils, the cell membrane and plasma membrane vesicles. Ascorbate treatment of cells leads to a new larger fibril with a diameter of approximately 40 nm. Antibodies to fibronectin and procollagen I react to these native collagen fibrils with an axial periodicity of approximately 70 nm. Fibronectin is clearly associated with native collagen fibrils produced by ascorbate treated cells and there is an asymetric distribution or segregation of fibronectin on these collagen fibrils with a 70 nm axial repeat.

Ascorbic Acid↗
PubMed1980

Response of plasma fibronectin to major body burn.

The ability of macrophages of phagocytize particulate matter is largely dependent on fibronectin, a nonspecific opsonin found in plasma. Fibronectin depletion, resulting in reticuloendothelial system (RES) depression, occurs following a variety of physical insults. RES depression may contribute to postinjury sequelae such as respiratory distress syndrome and septicemia. Fibronectin concentration was measured in the plasma of sheep with chronic lung lymph fistulas subjected to controlled thermal injury. Fibronectin levels were significantly (p < 0.05) decreased at 4, 24, 48, and 72 hours following burning. Fibronectin concentration decreased in parallel with serum albumin concentration; serum globulin concentrations did not decrease. Fibronectin concentration had an inverse relationship to lung lymph flow, a reflection of pulmonary transvascular fluid filtration rate. The role of fibronectin in the pathogenesis of postinjury respiratory distress syndrome deserves further exploration.

Adult↗
PubMed1980

Fibronectin presence in native collagen fibrils of human fibroblasts: immunoperoxidase and immunoferritin localization.

Fibronectin is a major constituent of the fibroblast extracellular matrix. Fibronectin binds to collagen, mediates fibroblast adhesion to collagen, and is synthesized and secreted into the medium of cultured fibroblasts. Affinity-purified antibodies to fibronectin and collagen were localized using the peroxidase-antiperoxidase method or with ferritin-coupled secondary antibodies. Using human fibroblasts cultured under routine conditions, fibronectin and procollagen I react in a nonperiodic manner with: 1) approximately 10 nm extracellular fibrils, 2) cell membrane, and 3) membrane-associated vesicles. All fibrils react with both antibodies, suggesting some form of codistribution of fibronectin and collagen in these fibrils. Treatment with ascorbate leads to the development of a larger diameter extracellular fibril, approximately 40 nm in diameter. These large diameter fibrils are clearly collagen fibrils as documented by the procollagen antibody reaction. Importantly, fibronectin is bound to or a constituent of these "native" or cellular made collagen fibrils. Fibronectin and procollagen antibodies localized with the peroxidase-antiperoxidase method have a 70 nm axial repeat of reaction product on ascorbate-treated fibroblasts. Localization of antibodies with ferritin-labeled secondary antibodies is less satisfactory, but supports the basic observations made with the unlabeled antibody enzyme method. This observation rules out any potential criticisms. Although it is more difficult to observe with immunoferritin, there is an indication that antibodies to fibronectin react with an axial periodicity on cellular produced collagen fibrils.

Collagen↗
PubMed1980

Fibronectin.

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Actins↗
PubMed1980

Ascorbate-induced fibroblast cell matrix: reaction of antibodies to procollagen I and III and fibronectin in an axial periodic fashion.

Fibronectin and procollagen types I and III are constituents of the extracellular matrix of human fibroblasts. Ultrastructural immunocytochemistry using the peroxidase anti-peroxidase method showed fibronectin and procollagen antibodies reacting in continuous fashion on 10 nm diameter extracellular fibrils on human fibroblasts. Intracellular localization showed an intense accumulation of procollagen within cells cultured under routine conditions. This accumulation appeared almost as if there were a blockade in secretion of procollagen under routine culture conditions. Cells treated with ascorbic acid do not have the dense intracellular accumulation of procollagens seen with the apparent blockade of secretion in cells cultured under routine conditions. Ascorbate treated cells also have a more pronounced extracellular accumulation of matrix fibronectin and procollagen constituents. At the electromicroscopic level a new 40 nm diameter fibril is formed after ascorbic acid treatment of human fibroblasts. Antibody to fibronectin and procollagen I and III are seen binding to the 40 nm diameter fibrils in a periodic or stuttered appearance. The fibronectin and procollagen antibodies react with a 70 nm axial repeat along these 40 nm fibrils formed after ascorbate treatment. These studies suggest that under routine culture conditions "precursor" fibrils of fibronectin and procollagen are formed. Ascorbic acid treatment leads to enhanced matrix formation. Ultrastructural studies clearly show antibodies to fibronectin bind to fibronectin on native collagen fibrils formed by human fibroblasts cultured with ascrobic acid. Lastly there is an asymmetric or 70 nm axial periodic distribution of fibronectin along these definitive or mature collagen fibrils formed after ascorbic acid treatment.

Antibodies↗
PubMed1979

Inhibition of blood coagulation factor XIIIa-mediated cross-linking between fibronectin and collagen by polyamines.

Soluble fibronectin is found in body fluids and media of cultured adherent cells. Insoluble fibronectin is found in tissue stroma and in extracellular matrices of cultured cells. Fibronectin is a substrate for factor XIIIa (plasma transglutaminase) and can be cross-linked to collagen and to the alpha chain of fibrin. We have used sodium dodecyl sulfate-polyacrylamide gel electrophoresis to investigate the possibility that factor XIIIa-mediated cross-linking is influenced by polyamines. Spermidine inhibited cross-linking between fibronectin and type I collagen, isolated alpha 1 (I) collagen chains, or iodinated cyanogen bromide fragment 7 of alpha 1 (I) chains (125I-alpha 1 (I)-CB7). Half-maximal inhibition of cross-linking between 125I-alpha (I)-CB7 and fibronectin was observed when 0.1 mM spermine or spermidine was present. Spermidine, 0.7 mM, partially inhibited cross-linking between fibronectin and the alpha chain of fibrin but failed to inhibit cross-linking between the fibrin monomers of a fibrin clot. Spermidine also failed to inhibit cross-linking between fibronectin molecules when aggregation of fibronectin was induced with dithiothreitol. In contrast, 0.7 mM monodanyslcadaverine inhibited fibronectin-collagen, fibronectin-fibrin, fibronectin-fibronectin, and fibrin-fibrin cross-linking. Spermidine or spermine, 0.7 mM, enhanced the cross-linking between molecules of partially amidinated fibronectin, suggesting that N1,8-(di-gamma-glutamyl)-polyamine cross-linkages were formed. Spermidine and spermine failed to enhance cross-linking between monomers of amidinated fibrin. These results indicate that physiologic concentrations of polyamines specifically disturb transglutaminase-catalyzed cross-linking between fibronectin and collagen.

Animals↗