Search PubMed⌕ Search

Biomedical subjects

K Rubin

Publications and source records attributed to K Rubin.

At least 109 records · Page 6Linked to original sources
PubMed1985

Incidence of arthritis and autoreactivity of anti-collagen antibodies after immunization of DBA/1 mice with heterologous and autologous collagen II.

Native type II collagens of rat, chick, bovine, human and murine origin have been used for immunization of male and female DBA/1 mice of different ages. The four heterologous collagens were able to induce arthritis in both male and female mice although the incidence of arthritis was higher in males. The onset of arthritis was sudden with severe lesions starting to appear 5- to 6-weeks after immunization. Mouse collagen II, on the other hand, caused arthritis exclusively in males. The onset of arthritis was in the latter case less dramatic and usually delayed until 12- to 14-weeks post immunization. Antibody production against both the immunogen and other type II collagens, including mouse collagen was seen in both arthritic and non-arthritic animals, and antibody titres against both the collagen used for immunization and mouse collagen were higher in the sera from arthritic than in identically immunized non-arthritic animals. Total amounts of auto-anticollagen II antibodies were, however, more dependent on which collagen preparation was used for immunization than on whether the immunized mice developed arthritis or not. These results indicate that arthritis induction in mice is not dependent solely on the levels of autoreactive anti-collagen II antibodies.

Animals↗
PubMed1984

Interactions of mammalian cells with collagen.

Isolated stationary cells recognize and adhere to immobilized extracellular matrix (ECM) components. These processes are mediated by specific receptor-ligand types of interaction. The formation of cell-ECM contacts influences subsequent cellular behaviour, such as the promotion of cell survival, epithelial cell polarization, and cell differentiation. The binding reaction between cells and collagen is discussed in this paper in terms of findings from studies with two cell systems, adult rat hepatocytes and rat cardiac myocytes. Isolated adult rat hepatocytes adhere to or bind laminin, fibronectin, heparan sulphate and collagen. We have characterized the interaction of hepatocytes with collagen and have isolated a glycoprotein fraction from rat liver membranes that contains collagen-binding components. The ability of rat cardiac myocytes to recognize ECM components depends on the state of cell maturation. Myocytes isolated from neonatal rats adhere to the interstitial collagens (types I-III), to collagen types IV and V, to fibronectin and to laminin. In contrast, myocytes isolated from adult rats bind effectively only to collagen type IV and laminin and bind much less effectively to fibronectin. Furthermore, antibodies raised against neonatal myocyte membranes inhibit the adhesion of both neonatal myocytes and hepatocytes to interstitial collagens, but antibodies raised against adult myocyte membranes lack these effects. These observations indicate that similar collagen-binding molecules are present on such diverse cells as hepatocytes and neonatal myocytes and that these components might be lost during cell maturation.

Animals↗
PubMed1984

Recognition of extracellular matrix components by neonatal and adult cardiac myocytes.

Recognition of extracellular matrix (ECM) components by isolated cardiac myocytes from neonatal (4-5 days postpartum) and adult rats was determined by measuring cell attachment to substrates made of ECM components. The substrates were petri dishes coated with either fibronectin, laminin, native monomers of collagen types I, II, III, IV, and V, denatured collagen, or gels containing reconstituted collagen fibers. Adult myocytes attached efficiently to laminin and type IV collagen, weakly to fibronectin, but not at all to the other types of collagen. Neonatal myocytes attached well to all types of collagen and to fibronectin and laminin. Antibodies raised against surface membranes of neonatal myocytes, adult myocytes, or adult hepatocytes were assayed for their ability to inhibit cell attachment to the various ECM substrates. Antibodies against the surface of neonatal myocytes as well as antibodies against the hepatocyte cell surface inhibited the attachment of neonatal myocytes and hepatocytes to collagen but not to fibronectin. Antibodies against the adult myocyte cell surface did not inhibit the attachment of neonatal myocytes or hepatocytes to ECM components. These results indicate the presence of binding molecules on the surface of neonatal myocytes that are involved in the recognition of collagen at a time when collagen is being secreted and formed into a three-dimensional network that attaches to the cell surface of the myocytes. This recognition and adhesion to collagen occurs by a mechanism independent of fibronectin. The binding molecules for collagen could not be detected on normal adult myocytes isolated at a time when the formation of the collagen network has already been completed.

Aging↗
PubMed1984

Hypoglycemic hemiplegic syndrome.

Hypoglycemia must be considered in any patient with an acute change of mental status or in a patient who shows a focal neurological deficit. Treatment with high IV glucose concentrations can save the patient from grave irreversible neurological sequelae and death.

Female↗
PubMed1983

Binding of fibronectin to Staphylococcus strains.

Fibronectin, a major protein component of plasma and loose connective tissue has previously been shown to bind to several strains of Staphylococcus aureus. We examined a large number of strains of different species of Staphylococcus with respect to their ability to bind fibronectin. The relative numbers of strains defined as fibronectin-binders among the different species were as follows: S. aureus (22 of 23), S. haemolyticus (5 of 5), S. warneri (8 of 11), S. hyicus (5 of 6), S. hominis (13 of 17), S. saprophyticus (11 of 20), S. epidermidis (4 of 7), and S. simulans (8 of 10). Only three species showed a predominance of nonbinders over binders: S. capitis (4 of 14), S. xylosus (0 of 4), and S. cohnii (3 of 11). These data indicate that staphylococcal species isolated from soft tissue infections frequently have the ability to bind fibronectin and suggest that the ability to bind to this protein may contribute to the virulence of coagulase-positive and coagulase-negative staphylococci.

Fibronectins↗
PubMed1982

Binding of fibronectin to the surface of group A, C, and G streptococci isolated from human infections.

Sixty-nine haemolytic and non-haemolytic streptococcal strains were isolated from various human infections and serogrouped with the coagglutination test. The amount of 125I-fibronectin bound to bacterial cells in a standard assay was determined. Most of the group A, C, and G strains were able to bind fibronectin. None of the group B or D strains bound significant amounts of fibronectin. Group A, C, and G streptococci appear to preferentially bind the N-terminal region of the fibronectin molecule because the 25K N-terminal fragment of the protein could effectively inhibit the binding of 125I-fibronectin to cells. Furthermore, the ability of representative strains of group A, C, and G to bind fibronectin was markedly reduced after trypsin treatment of the cells. Fibronectin binding components released from one strain by trypsin treatment inhibited the binding of 125I-fibronectin to all group A, C, and G streptococci strains. These findings indicate similarities among fibronectin binding proteins of the three groups of streptococci tested. However, the relative susceptibility to trypsin of fibronectin receptors of the three strains differed as did the relative potency of the inhibitory activity of receptors solubilized from different strains. Binding of fibronectin to the cell surface of group A, C, and G streptococci may contribute to virulence, for instance by promoting specific attachment to exposed fibronectin in open wounds and tissue lesions.

Fibronectins↗
PubMed1981

Substrate adhesion of rat hepatocytes: mechanism of attachment to collagen substrates.

Attachment of rat hepatocytes to collagen, which occurs without the aid of fibronectin, was found to be a time-dependent reaction characterized by an initial lag phase of 10-20 min before stable attachment bonds began to form. Increasing the density of molecules in the collagen substrates enhanced the rate of cell attachment. The hepatocytes attached essentially equally well to all the collagen types tested (types I, II, III, IV and V). The initial rate of cell attachment was more rapid to native collagen than to denatured collagen or alpha 1(I) chains, apparently indicating different affinities of the cells for these substrates. However, if cells were incubated for 60 min or more, efficient attachment occurred to the alpha 1(I) chain and to all cyanogen-bromide-treated peptides tested (alpha 1-CB2, alpha 1-CB3, alpha 1-CB4, alpha 1-CB5, alpha 1-CB6A, alpha 1-CB7, alpha 1-CB8, alpha 2-CB2, alpha 2-CB3 and alpha 2-CB4) but not to the aminopropeptide of type I procollagen. A low but significant degree of attachment also took place to substrates made of synthetic peptides with the collagen-like structures (Gly-Ala-Pro)n, (Gly-Pro-Pro)n and (Gly-Pro-Hyp)n, whereas no attachment was observed to polyproline. We suggest that the cell-binding sites in collagen have a simple structure and occur in multiple copies along the collagen molecule. Addition of collagen in solution inhibited initial cell attachment, an effect that persisted longer on substrates made of alpha 1(I) chain than on denatured collagen. The collected data are interpreted in terms of a model for cell-to-collagen adhesion where the formation of stable attachment bonds requires the binding of several low-affinity receptors, clustered at the site of adhesion, to collagen molecules in the substrate.

Animals↗