Culture filtrate antigens of Aspergillus fumigatus were fractionated by isoelectric focusing using a pH gradient of 4–6.5. Three fractions, namely, 18, 19 and 20 were pooled and subjected to immunochemical analysis. It contained a concanavalin A binding glycoprotein. Antibody raised against this component was used to prepare an affinity column of IgG-Sepharose and was used to purify crude culture filtrate antigens. This component produced three precipitin arcs in crossed immunoelectrophoresis using anti-A. fumigatus rabbit serum. This fraction has an isoelectric point of 6.5 and showed three components in two-dimensional electrophoresis with approximate molecular weights of 20, 40 and 80 kilo daltons. This antigen reacted with patient sera in the biotinavidin linked immunosorbent assay and showed high levels of anti-A. fumigatus IgG and IgE antibodies in allergic bronchopulmonary aspergillosis and IgG antibodies in aspergilloma. Both controls and Aspergillus skin test positive asthmatics showed only low levels of specific antibodies. Because of the purity of this antigen, its potential use as a standardized antigen in the detection of antibody is discussed.
1. Methyl retinoate has been converted into methyl 5,6-monoepoxyretinoate by reaction with monoperphthalic acid. The epoxy acid ester on alkaline hydrolysis gave 5,6-monoepoxyretinoic acid. 2. Treatment of the 5,6-monoepoxy compounds with ethanolic hydrochloric acid gave the corresponding 5,8-epoxy (furanoid) compounds. 3. With lithium aluminium hydride, the acid and the ester groups were selectively reduced to primary alcohols. 4. Administration of methyl 5,6-monoepoxyretinoate intraperitoneally and subcutaneously had good growth response in vitamin A-deficient rats. 5. 5,6-Monoepoxyretinoic acid, when given intraperitoneally as the sodium salt, was 157% as active as all-trans-retinyl acetate. 6. Methyl 5,6-monoepoxyretinoate was hydrolysed to the epoxy acid by rat-liver homogenate. It had 35% of the biological activity of all-trans-retinyl acetate in the rat when given orally.
1. retro-Retinyl acetate was shown to exert its biological activity by conversion into vitamin A. 2. When administered orally, retro-retinyl acetate was hydrolysed to retro-retinol in the intestine, isomerized to retinol and esterified before being transported to the liver for storage. 3. Administration of the compound at as high a dose as 4.0mg./day for 4 days led to the accumulation of both vitamin A and retro-vitamin A in the liver. The amount of retro-vitamin A in liver gradually decreased until it was almost completely converted into vitamin A in 18 days. 4. Intraperitoneal administration of the compound led to the accumulation of both vitamin A and retro-vitamin A in liver and other tissues. No vitamin A was detected in any tissue of rats receiving retro-retinyl acetate intraperitoneally after enterectomy. 5. The small intestine is the major site of conversion of retro-vitamin A into vitamin A. The conversion could also be demonstrated by everted intestinal sacs. 6. The biological potency of retro-retinyl acetate determined by the rat-growth assay was 20.5% that of all-trans-retinyl acetate, when given orally.
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