Search PubMed⌕ Search

Biomedical subjects

D F Mosher

Publications and source records attributed to D F Mosher.

At least 163 records · Page 9Linked to original sources
PubMed1983

Cultured human fibroblasts synthesize and secrete thrombospondin and incorporate it into extracellular matrix.

Thrombospondin, a major glycoprotein released from alpha granules of thrombin-stimulated platelets, is a disulfide-bonded trimer of 160-kilodalton subunits. Cultured human foreskin and fetal lung fibroblasts secreted thrombospondin (determined by enzyme-linked immunosorbent assay) into the culture medium in a time-dependent manner (15.7 and 5.8 micrograms per 10(6) cells per 24 hr, respectively); secretion was blocked by cycloheximide. [3H]Thrombospondin was isolated from [3H]leucine-labeled fibroblast postculture medium and from cell layers with rabbit polyclonal or mouse monoclonal anti-thrombospondin coupled to staphylococcal protein A-Sepharose. The immunologically isolated [3H]thrombospondin migrated in NaDodSO4/polyacrylamide gels with purified marker platelet thrombospondin both with and without reduction. Immunofluorescence microscopy using rabbit polyclonal and mouse monoclonal anti-thrombospondin antibodies localized thrombospondin to the fibrillar extracellular matrix surrounding the cells. Thus, cultured human fibroblasts secrete thrombospondin and incorporate it into the extracellular matrix.

Cells, Cultured↗
PubMed1983

Binding of plasma fibronectin to cell layers of human skin fibroblasts.

Human plasma fibronectin bound to confluent cell layers of cultured human-skin fibroblasts in two distinct pools. Initial binding of fibronectin occurred in a deoxycholate-soluble pool (Pool I). Binding in Pool I was reversible and reached a steady state after 3 h. After longer periods of incubation, fibronectin became bound in a deoxycholate-insoluble pool (Pool II). Binding in Pool II was irreversible and proceeded at a linear rate for 30 h. After 30 h of incubation, a significant proportion of fibronectin bound in Pool II was present as disulfide-bonded multimers. HT1080 cells, a human sarcoma cell line, did not bind fibronectin in either pool. Also, isolated cell matrices prepared by deoxycholate extraction did not bind fibronection. Binding of fibronectin in Pool I of normal fibroblasts occurred via specific, saturable receptors. There were 128,000 binding sites per cell, and KDiss was 3.6 X 10(-8) M. Fluorescence microscopic localization of fibronectin bound in Pool I and Pool II was performed using fluorescein-conjugated fibronectin. Fluorescent staining in Pool I was present in a punctate pattern and in short, fine fibrils. Pool II fluorescence was exclusively in coarse, dense fibrils. These data indicate that plasma fibronectin may become incorporated into the tissue extracellular matrix via specific cell-surface receptors.

Binding Sites↗
PubMed1983

Effects of subinhibitory concentrations of antibiotics on Staphylococcus aureus interactions with fibronectin.

Bacterial adherence to host tissues relies on interactions between tissue macromolecules and bacterial surface molecules. One of the major predisposing factors to infection with Staphylococcus aureus is trauma to tissues. A common element in traumatized tissues is fibronectin. In previous studies, we have shown that fibronectin binds to Staph. aureus. In this paper, we have investigated the effects of subinhibitory concentrations of antibiotics on fibronectin interactions with Staph. aureus. Exposure of Staph. aureus to 1/4 MIC of penicillin increases the number of binding sites and enhances adherence of Staph. aureus to a collagen-fibronectin matrix. Chloramphenicol, erythromycin, clindamycin, and U57,930E all decreased the number of binding sites. Also, U57,930E reduced Staph. aureus adherence to a collagen-fibronectin matrix. Taken together, these data suggest that penicillin may enhance Staph. aureus adherence to tissue fibronectin whereas U57,930E might reduce such binding.

Anti-Bacterial Agents↗
PubMed1983

Subinhibitory concentrations of antibiotics alter fibronectin binding to Staphylococcus aureus.

Fibronectin, a high-molecular-weight glycoprotein, is found in plasma and on mammalian cell surfaces. Recent reports have suggested that bacterial-fibronectin interactions play a role in bacterial attachment to host cells. Subinhibitory concentrations of lincosamines, erythromycin, and chloramphenicol decreased fibronectin binding to Staphylococcus aureus, whereas beta-lactam antibiotics enhanced this interaction.

Anti-Bacterial Agents↗
PubMed1983

Plasma fibronectin level and clinical status in cardiac surgery patients.

To determine whether changes in plasma fibronectin concentration were related to the development of postoperative complications, we studied both plasma fibronectin concentration and the postoperative clinical course for 41 patients undergoing elective cardiopulmonary bypass surgery. Patients were divided retrospectively into three groups based on their hospital course. Group I (n = 21) had mild complications, group II (n = 15) had moderate complications, and group III (n = 5) had severe complications. Fibronectin was monitored preoperatively, intraoperatively, and postoperatively until discharge. Although fibronectin levels were unaffected by induction of anesthesia, a decrease in fibronectin concentration was seen after bypass in all patients. This decline was transient, however, and fibronectin concentration rose within 4 to 5 hr after the end of surgery. A subsequent fall to a level below the lower limit of normal (less than 180 micrograms/ml) was consistently seen only in critically ill (group III) patients and coincided with adverse changes in their clinical status.

Aged↗
PubMed1982

Acquired factor XI deficiency in systemic lupus erythematosus.

A variety of coagulation abnormalities has been described in systemic lupus erythematosus (SLE). We report a unique SLE patient with an acquired factor XI deficiency. The low factor XI levels were not due to a classical coagulation inhibitor, but to a plasma factor (probably an immunoglobulin) that selectively bound factor XI. The factor XI deficiency improved after treatment with corticosteroids. Thus it is possible that in SLE immune complexes may bind clotting factors making them unavailable for use in the coagulation cascade.

Blood Coagulation Tests↗
PubMed1982

Fibronectin binding to Staphylococcus aureus.

Bacteria are able to interact with a number of macromolecules which act as opsonins or tissue-adherence factors. Because soluble fibronectin may be important factors. Because soluble fibronectin may be important in the phagocytic removal of bacteria and insoluble fibronectin may serve as a bridge between bacteria and host tissues, we have characterized the binding of soluble plasma fibronectin to Staphylococcus aureus as a first step to understanding these interactions. The binding of 125I-fibronectin to clinical and laboratory strains of S. aureus was studied. Bound fibronectin was separated from free fibronectin by centrifugation. Specific binding was determined by subtracting the amount bound in the presence of excess fibronectin from the total amount bound. We found that (i) fibronectin bound saturably, irreversibly, and noncovalently to S. aureus when the binding reaction was carried out at pH 7.4 or greater; (ii) S. aureus harvested in logarithmic phase of growth from media buffered to pH 8.4, and from brain-heart infusion media which demonstrated the greatest number of fibronectin-binding sites; (iii) high molecular weight dextrans, fibrinogen, cyanogen bromide fragment 7 of collagen, cationic proteins, dibromide fragment 7 of collagen, cationic proteins, dithiothreitol, and protein A did not alt er fibronectin binding to S. aureus; (iv) nonsaturable binding occurred below pH 7.0 with peak binding occurring at pH 5.8; and (v) there were marked differences in the amounts of fibronectin that bind to different strains of S. aureus. S. aureus ATCC 25923, when harvested in logarithmic phase of growth from tryptic soy broth and tested for fibronectin binding in (2-hydroxyethyl)-1-piperazineethanesulfonic acid-buffered saline, pH 7.4, had 7500 binding sites/organism with an apparent association constant of 5.6 X 10(9) M-1.

Fibronectins↗
PubMed1982

Conformational states of fibronectin. Effects of pH, ionic strength, and collagen binding.

Human plasma fibronectin was enzymatically labeled with dansylcadaverine using plasma Factor XIIa. Fluorescence polarization studies of dansylcadaverine-labeled fibronectin indicate that fibronectin has a significant degree of chain flexibility in physiologic solution and that there is an increase in chain flexibility at high pH or ionic strength. Binding of a collagen peptide to dansylcadaverine-fibronectin results in a decrease in fluorescence polarization, suggesting that such binding causes a conformational change which also results in increased chain flexibility.l Quasielastic light scattering and intrinsic viscosity measurements of fibronectin were performed under physiologic conditions and at high pH and ionic strength. Shape calculations based on these data indicate that fibronectin is in an elongated configuration under physiologic conditions and further unfolds at high pH or ionic strength into a very flexible, strand-like configuration. Light scattering studies of fibronectin after binding of a collagen fragment indicate that such binding results in a decrease in the diffusion coefficient, suggesting that collagen binding also results in a partial unfolding of fibronectin. These results suggest that published electron micrographs of fibronectin showing a long, strand-like molecule do not reflect the conformation of plasma fibronectin under physiologic conditions; fibronectin, however, may assume an unfolded conformation upon binding to collagen in the tissue matrix.

Cadaverine↗
PubMed1982

Glomerular and vascular injury in mice following immunization with heterologous and autologous fibronectin.

Random bred Swiss-Webster mice were immunized with either autologous (MFN) or heterologous guinea pig (GPFN) denatured serum fibronectin. Immunofluorescent, light and electron microscopic examination of renal tissues demonstrated glomerular changes, consisting primarily of endothelial and mesangial cell hypertrophy with expansion of the mesangial matrix. Evagination of mesangial cytoplasm into capillary lumens and balloon-like structures were characteristic of affected glomeruli. The histopathologic alterations were present in varying degrees of severity of all fibronectin treated animals, with slightly more extensive glomerular proliferation seen in animals immunized with heterologous (GPFN) fibronectin as compared to mice immunized with autologous (MFN) protein. Perivascular mononuclear cell infiltration with edematous changes in medial smooth muscle cells occurred in renal vessels. The vasculature of the liver and lung also showed mononuclear cell infiltrates in the adventitia. These studies lead us to conclude that an immune response to either heterologous or autologous denatured serum fibronectin can induce glomerular sclerotic changes, cellular hyperplasia, and vascular injury.

Animals↗
PubMed1982

Synthesis and secretion of thrombospondin by cultured human endothelial cells.

Thrombospondin, the major glycoprotein released from alpha-granules of thrombin-stimulated platelets, is a disulfide-bonded trimer of 160 kilodalton subunits and apparently functions as a platelet lectin. Because cultured human umbilical vein endothelial cells synthesize and secrete a glycoprotein (GP-160) which is a disulfide-bonded multimer of 160 kdalton subunits, the possibility that GP-160 is thrombospondin was investigated. Tritiated GP-160 could be immunoisolated from [3H]leucine-labeled endothelial cell postculture medium using a rabbit antiserum to human platelet thrombospondin. Thrombospondin and GP-160 comigrated in two different two-dimensional electrophoretic systems. Both proteins are disulfide-bonded trimers of acidic 160-kdalton subunits. A competitive radioimmunoassay for binding of 125I-thrombospondin to the rabbit antibodies indicated that 49 micrograms of thrombospondin antigen per 10(6) confluent endothelial cells accumulated in postculture medium over 24 h. Thus, endothelial cells secrete large amounts of a glycoprotein that is identical or very similar to platelet thrombospondin.

Cells, Cultured↗
PubMed1982

Protein C, an antithrombotic protein, is reduced in hospitalized patients with intravascular coagulation.

Activated protein C is a potent anticoagulant and profibrinolytic enzyme that can be derived from the vitamin-K-dependent serine protease zymogen, protein C, by the action of thrombin. Protein C antigen concentration was determined in plasmas from normals (n = 40) and from 38 patients with intravascular coagulation as evidenced by positive FDP (greater than micrograms/ml). Plasma protein C was 4 micrograms/ml in normals and was significantly depressed (less than 2 SD below the mean of normals) in 19 of the 38 patients. Of 15 patients with suspected intravascular coagulation but normal FDP, protein C was decreased in 5 individuals; 3 of these 5 patients had liver disease. Based on these results, we suggest that extensive activation of the coagulation system in vivo causes a significant consumption of protein C, presumably due to its activation by thrombin and subsequent clearance.

Antigens↗
PubMed1981

Cross-linking and binding of fibronectin with asymmetric acetylcholinesterase.

The similarities between the tail of asymmetric acetylcholinesterase (AcChE) and collagen prompted us to investigate if asymmetric AcChE, like collagen, can interact with fibronectin. Gradient centrifugation studies revealed that asymmetric, but not globular, AcChE bound to fibronectin and could be cross-linked covalently to fibronectin by plasma transglutaminase. The interaction of asymmetric AcChE with fibronectin paralleled the interaction of fibronectin with collagen. These results raise the possibility that fibronectin may be involved in attaching asymmetric AcChE to cell surfaces.

Acetylcholinesterase↗