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Biomedical subjects

S Hirani

Publications and source records attributed to S Hirani.

24 records · Page 2Linked to original sources
PubMed1980

Biochemical studies on a case of feline mannosidosis.

Evidence is presented for the biochemical diagnosis of the first case of feline mannosidosis. A marked deficiency of acidic alpha-D-mannosidase in the brain, kidney and liver and excessive excretion of mannose-rich oligosaccharides in the urine were found in a kitten suffering from a nervous disorder. Residual acidic alpha-D-mannosidase, ranging from 2 to 5.5% of the normal activity, was observed in the tissues of the affected kitten. It has similar kinetic and physicochemical properties to the normal activity. The amount of mannose in the urine of the affected kitten was 19-fold greater than in a comparable control, and the molar ratio of mannose to N-acetylglucosamine was approx. 6 : 1. High concentrations of neutral oligosaccharides were detected in the urine. The predominant oligosaccharide appeared to be a hexasaccharide. The biochemical features of bovine, feline and human mannosidosis are compared, and it is concluded that feline mannosidosis may be a useful animal model for studying the human disease.

Animals↗
PubMed1980

Plasma alpha-D-mannosidase in mucolipidosis II and mucolipidosis III.

There is a marked increase in the acidic alpha-D-mannosidase in the plasma of a patient with mucolipidosis II and of a patient with mucolipidosis III. A small proportion (3--4%) of this acidic alpha-D-mannosidase does not bind to concanavalin A-Sepharose, suggesting an alteration in the glycosylation and some of the enzyme in these disorders. A slight elevation in intermediate alpha-D-mannosidase was also demonstrated in these samples by using a differential assay for the acidic and intermediate alpha-D-mannosidase activities. A combination of chromatography on concanavalin A-Sepharose and Sephadex G-200 showed that intermediate alpha-D-mannosidase components I2 and I4, which account for approximately 80% of the intermediate activity in normal plasma, were also present in ML II and ML III plasma. The minor intermediate alpha-D-mannosidase components in normal plasma, I1 and I3 were either present in small amounts or not detected. These results suggest that a defect in intermediate alpha-D-mannosidase is unlikely to be the primary defect in these disorders.

Adolescent↗
PubMed1979

The multiple forms of alpha-D-mannosidase in human plasma.

The acidic alpha-D-mannosidase in human plasma closely resembles liver acidic alpha-D-mannosidase in its affinity for concanavalin A-Sepharose, molecular weight and resolution into multiple components on DEAE-cellulose. A combination of chromatography on concanavalin A-Sepharose and gel filtration on Sephadex G-200 and Sepharose 6B suggests that four forms of intermediate alpha-D-mannosidase, which differ either in their molecular weight of affinity for concanavalin A, exist in human plasma. A practical classification and nomenclature for the multiple forms of intermediate alpha-D-mannosidase in plasma based on molecular weight and affinity for concanavalin A is proposed. Multiple forms of intermediate alpha-D-mannosidase were also observed by ion-exchange chromatography on DEAE-cellulose, but there was not a simple correlation between these forms and those obtained with the other separation procedures. The form of intermediate alpha-D-mannosidase least abundant in plasma, approx. 7% of the activity, has very similar properties to the neutral alpha-D-mannosidase in human liver. In contrast, the other three forms of intermediate alpha-D-mannosidase, which account for over 90% of the activity, do not appear to be present in liver, except perhaps in trace amounts.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1977

Measurement of the alpha-mannosidase activities in human plasma by a differential assay.

A differential assay based on their difference in thermal stability has been used to measure the acidic and true intermediate alpha-mannosidases in the plasma of cntrols and individuals homozygous or heterozygous for mannosidosis. The intermediate activity was found to be independent of age, sex or mannosidosis genotype. The acidic alpha-mannosidase did not vary significantly with age or between sexes for groups of the same age. The concentrations of acidic and intermediate alpha-mannosidase showed a positive correlation for adults but not for children. The ratio of acidic to true intermediate alpha-mannosidase might therefore be a useful secondary test for the detection of adult heterozygotes for mannosidosis.

Adolescent↗
PubMedDate not supplied

Integrated clinical experience with tolerogenic peptides.

More than 2,000 patients have been dosed in the clinical development programs for Allervax Cat and Ragweed products in North America, Europe and Japan. Two peptides derived from Fel d 1 and three peptides derived from Amb a 1 were selected for clinical development following T cell epitope mapping of these major allergens. Clinical activity has been demonstrated in several dose regimens containing 75 and 750 microg of each component peptide given in 4-6 doses over 2-4 weeks. Greater activity has been seen with higher doses. Immediate hypersensitivity to treatment peptides is rarely seen and can be avoided through patient screening. A putative pathway resulting in histamine-mediated but IgE-independent allergic symptoms, similar in nature and severity to natural allergen exposure, has been identified in association with treatment. These manifestations are more pronounced in cat than ragweed allergy and are consistent with the respective diseases. When desired, the symptoms may be ameliorated with administration of H1 blockers prior to symptom appearance. The seasonal rise in allergen-specific IgE is blunted in association with therapy. Antigen-specific antibody levels (IgE and IgG), T cell primary proliferation and immediate skin test sensitivity will be followed in longer-term studies.

Allergens↗