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M Hook

Publications and source records attributed to M Hook.

24 records · Page 2Linked to original sources
PubMed1990

Endothelial cells secrete a factor that promotes fibroblast contraction of hydrated collagen gels.

Bovine aortic endothelial cells (BAEC), grown in vitro, are shown to synthesize and secrete factor(s) that stimulate fibroblasts to contract collagen matrices. The amount of contraction-promoting activity in the conditioned media is dependent on conditioning time and the number of cells in the culture. Production of the contraction-promoting activity continues at a high stable level for at least 5 d in serum-free medium but is abolished when the cells are exposed to an inhibitor of protein synthesis. The mechanism of action of the contraction factor(s) derived from endothelial cells was compared with that of unidentified serum factors. The endothelial cell-secreted factor(s) depends on active protein synthesis by the target cell but does not need to be present during the contraction process. The serum factors on the other hand promote collagen contraction in the absence of de novo protein synthesis but need to be continuously present. Preliminary biochemical characterization of the contraction-promoting factors produced by endothelial cells revealed properties similar to those of previously identified growth factors. However, the BAEC-secreted factor was found to be distinct from a previously identified contraction-promoting transforming growth factor beta.

Animals↗
PubMed1990

Peptide analogs to a fibronectin receptor inhibit attachment of Staphylococcus aureus to fibronectin-containing substrates.

Binding of cells of Staphylococcus aureus to fibronectin has been proposed as a mechanism of bacterial adhesion to host tissues. In this study, we have attempted to define the role of a recently identified fibronectin receptor in the adhesion of staphylococcal cells to fibronectin-containing substrates by using different receptor analogs as potential inhibitors of bacterial adherence. The results showed that synthetic peptides D1, D2, and D3, corresponding to variations of a repeated unit in the fibronectin-binding domain of the receptor, and ZZ-FR, a chimeric protein containing the fibronectin-binding domain of the receptor with the D1, D2, and D3 sequences, inhibited the attachment of staphylococcal cells to microtiter wells coated with intact fibronectin or with the 29-kilodalton amino-terminal fragment of fibronectin. The chimeric protein ZZ-FR also partially inhibited the adherence of staphylococci to human plasma clots formed in vitro but had no effect on bacterial adhesion to clots formed from fibronectin-depleted plasma. These data confirm previous reports suggesting that fibronectin may serve as a substrate for adhesion of staphylococcal cells and indicate that bacterial adhesion is mediated by the identified fibronectin receptor. Furthermore, analogs to the fibronectin receptor can be used to inhibit the adhesion of bacterial cells to these model substrates, and these analogs may be of clinical use.

Animals↗
PubMed1990

Bacteroides gingivalis and Bacteroides intermedius recognize different sites on human fibrinogen.

Bacteroides (Porphyromonas) gingivalis and Bacteroides (Porphyromonas) intermedius have been implicated in the etiology of human periodontal diseases. These organisms are able to bind and degrade human fibrinogen, and these interactions may play a role in the pathogenesis of periodontal disease. In attempts to map the bacterial binding sites along the fibrinogen molecule, we have found that strains of B. gingivalis and B. intermedius, respectively, recognize spatially distant and distinct sites on the fibrinogen molecule. Isolated reduced and alkylated alpha-, beta-, and gamma-fibrinogen chains inhibited binding of 125I-fibrinogen to both Bacteroides species in a concentration-dependent manner. Plasmin fragments D and to some extent fragment E, however, produced a concentration-dependent inhibition of 125I-fibrinogen binding to B. intermedius strains but did not affect binding of 125I-fibrinogen to B. gingivalis strains. Radiolabeled fibrinogen chains and fragments were compared with 125I-fibrinogen with respect to specificity and reversibility of binding to bacteria. According to these criteria, gamma chain most closely resembled the native fibrinogen molecule in behavior toward B. gingivalis strains and fragments D most closely resembled fibrinogen in behavior toward B. intermedius strains. The ability of anti-human fibrinogen immunoglobulin G (IgG) to inhibit binding of 125I-fibrinogen to B. intermedius strains was greatly reduced by absorbing the IgG with fragments D. Absorbing the IgG with fragments D had no effect on the ability of the antibody to inhibit binding of 125I-fibrinogen to B. gingivalis strains. A purified staphylococcal fibrinogen-binding protein blocked binding of 125I-fibrinogen to B. intermedius strains but not to B. gingivalis strains.

Bacteroides↗
PubMed1988

Staphylococcal adhesion to collagen in intra-articular sepsis.

Ultrastructural studies of the cartilaginous articular surfaces of human and rabbit joints have shown that cartilage is the target substratum for adhesion by Staphylococcus aureus, leading to intra-articular sepsis. Transmission and scanning electron microscope studies demonstrated bacteria in intimate contact with acellular cartilage matrix surfaces, particularly with collagen fibres. Certain strains of Staphylococcus aureus used in these experiments reveal a high binding capacity to collagen that is derived from a cartilage matrix. These studies indicate that the pathogenesis of intra-articular sepsis is based on the ability of certain strains of staphylococci to bind preferentially to a cartilage matrix.

Animals↗
PubMed1983

Reduced sulfation of liver heparan sulfate in experimentally diabetic rats.

Analyses by anion exchange chromatography indicate that heparan sulfate proteoglycans isolated from the livers of experimentally diabetic rats have a reduced net negative charge as compared with heparan sulfate proteoglycans from control rats. In contrast, the size of the normal and diabetic proteoglycans are indistinguishable as are the size of individual polysaccharide chains when compared by gel chromatography. The reduced net negative charge of heparin sulfate from diabetic rats is shown to be caused by a reduced number of sulfate groups present in the diabetic heparan sulfate. Results are presented suggesting that one of the biosynthetic enzymes; the N-deacelylase, which tentatively has been identified as a regulatory enzyme affecting the sulfate content of the polysaccharide chains, may be inhibited in the diabetic rat.

Animals↗