| 1. |
- Musil, Kristina, et al.
(författare)
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Alteration of Proteoglycan Metabolism during the differentiation of 3T3-L1 fibroblasts into Adipocytes
- 1991
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Ingår i: Journal of Cell Biology. - 0021-9525. ; 114:4, s. 821-826
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Tidskriftsartikel (refereegranskat)abstract
- 3T3-L1 fibroblasts were induced to differentiate to 3T3-L1 adipocytes by dexamethasone, isobutyl-methylxanthine, and insulin. To study how differentiation affects extracellular matrix production, the accumulation of proteoglycans was studied by labeling the 3T3-L1 cells with [35S]sulphate for 24 h. The labeled proteoglycans were isolated from the medium and cell layer extracts by anion-exchange chromatography. They were then taken to gel filtration chromatography on Superose 6 before or after chondroitin ABC lyase digestion. Hyaluronan was determined by radioimmunoassay. The rate of accumulation of proteoglycans and hyaluronan in the control 3T3-L1 fibroblasts increased with time whereas it decreased slightly in the age matched adipocytes where the differentiation had proceeded, as judged by the change of morphology and increase of the activity of the adipose conversion markers glycerol-3-phosphate dehydrogenase and hormone sensitive lipase. The main change noted was that the adipocytes accumulated 50-70% less amount of small proteoglycans (decorin) in the medium than the fibroblasts did. The amount of large chondroitin/dermatan sulphate proteoglycans was also decreased but to a considerably smaller extent (30%). In the cell layer, heparan sulphate proteoglycan decreased by 60% as compared with the control cells. Thus, the differentiation of 3T3-L1 fibroblasts into adipocytes, which changes the morphology and the function of the cells, is also accompanied by a decreased net production especially of proteoglycans typical of fibrous connective tissue.
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| 2. |
- Oxelius, Vivi-Anne, et al.
(författare)
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Serum Gm Allotype development During Childhood
- 1999
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 1365-3083 .- 0300-9475. ; 50, s. 440-446
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Tidskriftsartikel (refereegranskat)abstract
- Gm allotypes are genetic variants of the immunoglobulin heavy G chains (IGHG) of IgG molecules, coded from chromosome 14q32, characterized by differences in amino acid epitopes of the constant heavy G chains and inherited in the Mendelian manner. Gm allotypes have influence on IgG subclass levels, and serum Gm allotype levels have been given for different Gm genotypes in adults. Four hundred and thirty healthy children, aged 1-15 years, were examined for serum Gm allotypes and IgG subclasses from the six most common Gm genotypes and different age groups were measured using competitive enzyme-linked immunosorbant assay and radial immunodiffusion methods. Quantities (in g/l) of G1m(a) and G1m(f) of IgG1, G2m(n) and G2m(-n) of IgG2 and G3m(g), and G3m(b) of IgG3 are given. Different maturation rates of the alternative Gm allotypes within IgG1, IgG2 and IgG3 were shown. G2m(n) development was strikingly retarded compared with G2m(-n) from the gamma2 locus. This was found comparing IgG2 levels from homozygous G2m(-n-n) and G2m(nn) individuals, but was also seen in heterozygous G2m(n-n) genotypes. From the gamma1 locus G1m(f) levels dominated significantly, but inconstantly, over G1m(a) levels in heterozygous G1m(af) individuals. In homozygous G1m genotypes, G1m(aa) compared with G1m(ff) of the same age, one or the other dominated, sometimes significantly. Serum levels of G3m(b) from the gamma3 locus of homozygous G3m(bb) individuals were increased significantly compared with G3m(g) levels of homozygous G3m(gg) individuals, in ages over 3 years. However, in heterozygous G3m(gb) individuals G3m(b) dominance was not evident. There is a relatively rapid development of G1m(f) molecules and a retarded development of G2m(n) in the Gm(f;n;b) haplotype. In comparison, G1m(a) is retarded and G2m(-n) is enhanced in the Gm(a;-n;g) haplotype. The retarded serum G2m(n) development is comparable with serum IgA development during childhood. Different maturation rates of Gm allotypes within the same IgG subclass provide further explanation for the variation of the antibody response during childhood. Quantitative Gm allotype determinations give information of the activity from IGHG genes. The genetic variation constitutes an additional basis for evaluation of IgG antibodies in different diseases in childhood
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