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- Lohmander, Stefan, et al.
(författare)
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Chemical and metabolic heterogeneity of chondroitin sulfate and keratan sulfate in guinea pig cartilage and nucleus pulposus
- 1973
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Ingår i: Biochimica et Biophysica Acta. General Subjects. - : Elsevier BV. - 0304-4165. ; 304:2, s. 430-448
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Tidskriftsartikel (refereegranskat)abstract
- Chondroitin sulfate and keratan sulfate in guinea pig costal cartilage, nasal septum cartilage and nucleus pulposus were separated and fractionated by chromatography on CPC-cellulose, ECTEOLA-cellulose and Sephadex G-200 columns. Characterization of the chondroitin sulfates included determination of molecular weight and of the number, and position, of sulfate groups of the disaccharide units. Distinct chemical differences were found between the total fractions of chondroitin sulfate from the three tissues. Within the total fractions a marked heterogeneity was also apparent. The turnover of the two glycosaminoglycans was studied by using radioactive sulfate as precursor. The guinea pigs were killed at eight intervals, ranging from 30 min to 40 days after injection of the isotope. Total fractions of chondroitin sulfate from rib, nasal septum and nucleus pulposus showed half-lives of about 80, 40 and 30 days, respectively. In addition, the existence of a second metabolic component with a faster turnover (half-life about 3 days) was indicated in chondroitin sulfate from all three tissues. Similarly, keratan sulfate from the rib contained a 'slow' component with a half-life of about 90 days and a 'fast' component with a half-life of 4 days. For keratan sulfate from nucleus pulposus only a single component was demonstrable; it had a half-life of about 30 days. Within the total fractions of both chondroitin sulfate and keratan sulfate from the three tissues studied, a considerable degree of metabolic heterogeneity was apparent between, and within, subfractions of differing molecular weight.
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- Lohmander, Stefan, et al.
(författare)
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In vitro studies on the effect of in vivo zinc deficiency on the formation of glycos-aminoglycans in rat costal cartilage
- 1972
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Ingår i: Acta Odontologica Scandinavica. - : Informa UK Limited. - 0001-6357 .- 1502-3850. ; 30:1, s. 89-96
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Tidskriftsartikel (refereegranskat)abstract
- The effects of in vivo zinc deficiency and restricted food intake, on the in vitro synthesis of glycosaminoglycans of rib cartilage were studied in the rat. 35S-sulfate and 14C-glucosamine were used as precursors. The glycosaminoglycans were separated on microcolumns and specific radioactivities determined for the different fractions. Chemical analyses showed that zinc deficiency or reduced food intake did not cause any qualitative or quantitative changes in the glycosaminoglycans. The radioassays indicated that zinc deficiency and reduced food intake, alone or combined, caused a somewhat lowered synthetic rate of chondroitin sulfate. In the discussion it is underlined that it seems difficult to determine conclusively the importance of zinc for the formation of the mucopolysaccharides through further in vivo deficiency studies, because of the difficulties to control and evaluate the inanition factor.
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- Lohmander, Stefan
(författare)
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Ion exchange chromatography of glucosamine and galactosamine in microgram amounts with quantitative determination and specific radioactivity assay
- 1972
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Ingår i: Biochimica et Biophysica Acta. General Subjects. - : Elsevier BV. - 0304-4165. ; 264:3, s. 411-417
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Tidskriftsartikel (refereegranskat)abstract
- A rapid method for the separation and quantitative determination, including radioassay, of glucosamine and galactosamine in microgram amounts is described. It is based upon the use of a column of Aminex A-5 ion exchange resin eluted with a phosphate buffer at pH 7.00 and 60 °C. From each fraction half the volume is used for a scaled down Elson-Morgan procedure and other half for liquid scintillation counting. Amounts of about 0.01-1 μmole of hexosamine may be separated and determined.
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- Lohmander, Stefan, et al.
(författare)
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Proteoglycans of mineralizing rib and epiphyseal cartilage
- 1975
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Ingår i: Biochimica et Biophysica Acta. General Subjects. - : Elsevier BV. - 0304-4165. ; 404:1, s. 93-109
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Tidskriftsartikel (refereegranskat)abstract
- Rib cartilage from growing guinea pigs and epiphyseal cartilage from Beagle puppie were separated into three fractions, representing non-mineralized, low mineralized, and high mineralized, tissue, by centrifuging finely ground material in acetone/bromoform density gradients. Following extraction under dissociative conditions, the proteoglycans were fractionated by density gradient ultracentrifugation under associative and dissociative conditions. With the onset of mineralization, the cartilage lost approximately half its content of proteoglycans. The proteoglycans remaining in the calcified cartilage differed in composition and in size from those of nonmineralized tissue. With the increased mineral content of the tissues the ratios of protein to polysaccharide, of chondroitin sulfate to keratan sulfate, and of 4-sulfated to 6-sulfated chondroitin sulfate increased in the proteoglycan fraction. Furthermore, gel chromatograms indicated decreased proportions of very high molecular weight proteoglycans, in mineralized tissue.
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- Lohmander, S., et al.
(författare)
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Secretion of proteoglycans by chondrocytes. Influence of colchicine, cytochalasin B, and β-d-xyloside
- 1979
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861. ; 192:1, s. 148-157
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Tidskriftsartikel (refereegranskat)abstract
- Chondrocytes obtained from epiphyseal cartilage of fetal guinea pigs or ear cartilage of young rabbits were cultured in monolayer. The influence of colchicine, cytochalasin B, and p-nitrophenyl-β-d-xylopyranoside on secretion of proteoglycans was investigated. Radioactive sulfate was used as a precursor. As observed previously in other systems, β-d-xylosides initiated the synthesis of free chondroitin sulfate chains, competing with the endogenous proteoglycan core protein acceptor. The molecular weights of the chondroitin sulfate chains synthesized both on the xyloside and on the core-protein acceptor in maximally stimulated cells were similar and significantly lower than in proteoglycans synthesized in the absence of xyloside. The size of the chondroitin sulfate chains synthesized on the xyloside was inversely related to the concentration of this compound. This finding suggests that the chain length is dependent on the ratio between available acceptor and chain-lengthening enzymes or precursors. Cytochalasin B, a microfilament-modifying agent, inhibited proteoglycan synthesis, without any effect on secretion. Cells treated with cytochalasin B could be stimulated with β-d-xyloside to synthesize free chondroitin sulfate chains to the same relative degree as cells with intact microfilaments. Colchicine, an antimicrotubular agent, partially inhibited synthesis and secretion of proteoglycan. However, cells treated with colchicine could be stimulated with β-d-xyloside to synthesize and secrete free chondroitin sulfate chains to about the same relative degree as cells with intact microtubules. The data suggest that microtubules may have a facilitatory rather than an obligatory role in the secretion of proteoglycans and that at least part of the effect of colchicine is located at or after the site of glycosaminoglycan synthesis.
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