Biomedical subjects
Publications and source records attributed to D Minter.
A new iridoid, pikuroside (1), was isolated from the roots of Picrorhiza kurroa, together with three known iridoids, picroside I (2), picroside II (3), and 6-feruloyl catalpol (4). The structure of 1 was established by interpretation and full assignments of NMR spectral data. Pikuroside (1) had no antiinflammatory activity, although the crude extract and picroside II (3) demonstrated moderate activity.
We carried out experiments to determine conditions for fibroblast adhesion to fibrinogen and fibrin substrata. Baby hamster kidney (BHK) cells did not attach to substrata composed of purified fibrinogen or fibrin. When cold-insoluble globulin (CIG) (plasma fibronectin) was bound to fibrinogen or fibrin substrata, adhesion of BHK sells was observed and the extent of adhesion was dependent upon the CIG conecntration. Binding of CIG to fibrinogen or fibrin substrata in the presence of Factor XIII (factor) under covalent crosslinking conditions resulted in a marked increased in the ability of the substrata to support cell adhesion. Control experiments indicated that CIG formed the sites on the fibrinogen and fibrin substrata to which the cells were attaching. In addition, the effect of factor XIII was shown to require covalent crossliking of CIG to the fibrinogen or fibrin, which involved a glutamine residue on the CIG molecule and could be prevented by prior crosslinking of CIG with putrescine or with itself. The enhanced ability of Factor XIII-crosslinked CIG substrata to support cell adhesion could not be accounted for by the absolute amount of CIG bound to the substrata. We present in this paper the possibility that the orientation of CIG on the substrata is the critical factor.
The purified fetal calf serum factor that promotes cell adhesion and spreading of baby hamster kidney cells on tissue culture substrata has been subjected to a variety of chemical modifications and then tested for activity. These studies have shown that modification of the carbohydrate portions of the factor by glycosidic enzymes or by periodate oxidation did not alter its ability to promote cell spreading. On the other hand, modification of some protein portions of the factor by proteolytic enzymes or by specific modification of -COOH groups, tyrosine residues, or tryptophan residues resulted in a marked inhibition of factor activity. Modification of protein -SH groups, -NH2 groups, or methionine residues did not affect factor activity. Control experiments indicate that the various modifications were directed at the activity of the factor and not its adsorption onto the substrata.
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Studies have been carried out to determine the effects of cold-insoluble globulin (CIG) on the attachment and spreading of baby hamster kidney cells on various collagen substrata. Cell attachment to native collagen substrata occurred in the absence of CIG just as fast as attachment to dried collagen or gelatin substrata occurred in the presence of CIG. On the other hand, cell attachment to dried collagen or gelatin was markedly reduced in the absence of CIG. Cell spreading also occurred on native collagen in the absence of CIG; however, CIG was absolutely required for cell spreading to occur on dried collagen or gelatin. Finally, anti-CIG antiserum or lactoperoxidase treatment inhibited cell spreading on CIG-coated substrata but not on native collagen substrata. The data are discussed in terms of the interaction of fibroblasts with collagen in situ.
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