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Summary:The most consistent effects of 0.2 mM L-ascorbate on monolayer cultures of rabbit articular chondrocytes were a diversion of incorporated radiosulfate into a pericellular matrix and enhancement of cell proliferation. Only with certain batches of fetal bovine serum (FBS) was there a cell-for-cell increase of proteoglycan synthesis. These actions increased as the cell inoculum rose from 0.5 to 2 x lo5 cells/T25 flask. Maximal effects of ascorbate and D-isoascorbate were found over a range of 0.05-0.2 mM. L-Dehydroascorbic acid was less effective than either, and no stimulatory action was exerted by L-cysteine, glutathione, dithiothreitol, rnethylene blue, or phenazine rnethosulfate. Ascorbate increased the hypro:pro ratio of newly synthesized proteins. p-Aminopropionitrile (1 mM) reduced the proportion of [3Hlhydroxy-proline and [35S]0,-proteoglycans in the ascorbate-supplemented matrix 3 1 and 7%, respectively. In corresponding electronmicrographs, the number of pericellular filaments was reduced. We conclude: (a) Ascorbate has a general anabolic effect on chondrocytes in culture and enhances matrix assembly through mechanisms other than its redox function; (b) deposition of proteoglycans in the matrix is not simply the result of mechanical entrapment by allysine-or hydroxyallysine-derived cross-linking of collagen; and (c) contradictory reports on the subject result from variations in the serum employed, inoculum density, and concentration of ascorbate. Key Words: Ascorbate-paminopropionitrile-Cell culture-Chondrocyte-Differentiation.Several quite contradictory reports describe the effect of ascorbate on proteoglycan synthesis by chondrocytes in culture. The older literature was reviewed by Jouis and co-workers (20). Most articles indicated that ascorbate does not promote proteoglycan synthesis or increases it only transiently (17) and sometimes depresses it (51). In contrast, we (23,29,40,52) and others (9,46) found that ascorbate increases radiosulfate incorporation in vitro. This is one of several anabolic actions of ascorbate. The mechanism involved in the deposition of the matrix has not been established. This article examines sources of the disparities in the literature, documents the specificity of the ascorbate action, and presents data relevant to the prevailing hypothesis that entrapment Of proteoglycan by tightly cross-linked collagen is the basis

A series of 6,7-dimethoxy-4-(substituted amino)quinolines, several 6,7-dimethoxy-4-aminoquinolinium iodides, and some miscellaneous 4-substituted quinolines were synthesized and evaluated for hypotensive activity in dogs. Several of the simple 4-(alkylamino)-6,7-dimethoxyquinolines exhibited good hypotensive activity, equal to that of the parent 4-amino-6,7-dimethoxyquinoline (1).

The effect of sodium selenite on DNA and sulfated proteoglycan synthesis by cultured rabbit articular and growth plate chondrocytes was studied as an in vitro model for Kashin-Beck disease. The selenium content of a defined medium (DMEM, fibroblast growth factor, insulin, and dexamethasone) was below the limit of dekction by isotope dilution mass spectrometry. The chondrocytes were viable in the Se-free basal medium. Selenite over a range of 5 x 10-9M to 5 X lO-'M had no stimulatory effect on DNA or sulfated proteoglycan synthesis by either type of chondrocyte or skin fibroblasts. Proliferation of bovine endothelial cells was enhanced by 5 X lO-'M Se. At Se concentrations of ~10-~1M, there was progressive inhibition of cell growth and radiosulfate incorporation of the connective tissue celks; bovine endothelial cells were more resistant. Twice equimolar concentrations of vitamins C and E exerted no protective effect against the cytotoxicity of higher concentrations of Se. Se supplementation also failed to stimulate growth of human infant chondrocytes. The model enabled simulation of conditions of hyposelenosis below those encountered in nature. The data provide no evidence that chondrocytes have idiosyncratic require-