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R Parekh

Publications and source records attributed to R Parekh.

23 records · Page 2Linked to original sources
PubMed1991

Abnormalities in the glycosylation of IgG in spouses of patients with rheumatoid arthritis. A family study.

Forty-seven members of eight families with a rheumatoid proband were analysed for abnormal glycosylation of IgG. The results (%G(o) which is the percentage of oligosaccharide chains lacking galactose) were corrected for age and expressed as SD units about the mean for the normal population. Seven of 8 probands, 3/8 spouses, 3/5 RA relatives and 4/26 non-RA relatives had %G(o) values greater than 1SD above the age corrected mean for the normal control population (P less than 0.001, less than 0.01, less than 0.005 and greater than 0.5 respectively). A further 13 spouse pairs were studied. Ten of 13 probands and 8/13 spouses had %G(o) values greater than 1SD above the mean (P less than 0.001 and less than 0.001 respectively). Thus in total, a strikingly high number of unaffected spouses had high %G(o) values (11/21). IgM, IgA and IgG rheumatoid factors were studied. While RA patients' sera showed a correlation between IgM and IgA rheumatoid factors and %G(o), (IgM, r = 0.41 0.05 greater than P greater than 0.02, IgA, r = 0.36, P = 0.05), no correlation between IgG RF and %G(o) was noted in the RA patients. No correlation was found between any of the RF classes and %G(o) in spouses and non-RA relatives.

Arthritis, Rheumatoid↗
PubMed1990

Enhancement of cyclosporin production in a Tolypocladium inflatum strain after epichlorohydrin treatment.

Following treatment of conidia of the cyclosporin producer fungus, Tolypocladium inflatum, with 0.15 M epichlorohydrin, strain M6 was isolated. The new strain exhibited a similar growth rate to the parent organism but more extensive conidiation and several-fold higher overall cyclosporin production. Strain M6 reached titres of 318 mg l-1 cyclosporin A in agar cultures, whereas in liquid medium it produced 140 mg l-1 cyclosporin A and 68 mg l-1 cyclosporin C. It also maintained a steady volumetric productivity of 0.48 mg l-1 h-1 cyclosporin A over 2 weeks of submerged cultivation in maltose-based semisynthetic medium. The new strain holds potential for improved cyclosporin production due to the superior titres and demonstrated capacity to sustain elevated production of cyclosporin for periods greater than the wild type.

Chlorohydrins↗
PubMed1988

Age-related galactosylation of the N-linked oligosaccharides of human serum IgG.

In a study of 151 normal, healthy individuals of both sexes varying in age from 1-70 yr, it was found that the relative incidence of agalactosyl (with both outer arms terminating in N-acetylglucosamine) N-linked oligosaccharides on total serum IgG decreased from birth to a minimum (at 25 yr of age) and then increased with age. The relative incidence of digalactosyl structures varied inversely to this, and the relative incidence of monogalactosyl structures was constant. Galactosylation of the N-linked oligosaccharides of the human serum IgG of normal individuals is therefore an age-related molecular parameter. Several reports have suggested that rheumatoid arthritis is associated with a decreased galactosylation of serum IgG (3-5). The normal variation in galactosylation with age as described here allows a true assessment of disease-associated changes in this parameter, and raises the possibility that one of the lesions in rheumatoid arthritis is an accelerated aging of the immune system. In addition, heterogeneity within age groups may be due to intrinsic differences in genetic endowment, or may reflect the impact of extrinsic factors (8).

Adolescent↗