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Biochemical and serological characteristics of soluble yeast phase antigens of Histoplasma capsulatum.

Soluble antigens of whole yeast-phase cells were extracted with a 0.1 M phosphate buffer containing 0.1 M sodium chloride and 0.02% iodacetate. After being separated by differential filtration into fractions less than or greater than 50,000 daltons these antigens were purified by molecular sieve and chromatographic separations on ionic exchange resins. Two high molecular weight fractions obtained from diethylaminoethyl-cellulose (DEAE) at pH 8.0 and 7.0 with tris (hydroxymethyl) aminomethane (Tris) buffer were M antigens; those obtained at pH 4.0 and 4.0 with salt were H antigens. The four fractions had protein to carbohydrate ratios of 7.3, 14.0, 8.4, and 6.5 respectively, and all had essentially the same amino acid composition with no methionine and tyrosine and little histodine, arginine, phenylalanine and lysine. They had high concentrations of glucose, less mannose and traces of galactose. The low molecular weight fractions had the new complex "Y antigen", M antigen with protein to carbohydrate ratios of 1.4, 1.4 and 0.3 respectively. The amino acid and sugar composition of Y antigen strongly resembled the composition of the low molecular weight H and M antigens. Unlike the high molecular weight antigens, these low molecular weight antigens had methionine in relatively high concentrations; they had the same sugars as their respective high molecular weight counterparts. The yeast phase antigens differed from their respective mycelial counterparts in the following ways: glucose was the major sugar in the yeast phase with less amounts of mannose and traces of galactose, whereas in the mycelial antigens, mannose was the major sugar, with lesser amounts of galactose, and hexosamine. The H and M antigens of the yeast phase had high concentrations of glycine and alanine, whereas in the mycelial phase, these antigens had high concentrations of threonine and proline; the H and M antigens of the yeast phase had 5 to 16 times the protein to carbohydrate ratio observed for the same antigens of histoplasmin.

Amino Acids↗

Isolation of Histoplasma capsulatum from the air in the Aguas Buenas Caves, Aguas Buenas, Puerto Rico.

White mice were used to isolate H. capsulatum from the air in the Aguas Buenas Caves, Puerto Rico. Based on the infection of mice, the ten test sites yielded positive results for the presence of the fungus. Air currents through this cave are believed to be the most important factor responsible for the even distribution of H. capsulatum. Cultural differences concerning spore concentrations were observed. Age and sex of the exposed mice do not seem to play a role in acquiring histoplasmosis.

Air Microbiology↗

Ultrastructural changes produced by ketoconazole in the yeast-like phase of Paracoccidioides brasiliensis and Histoplasma capsulatum.

The ultrastructural changes produced by ketoconazole in the yeast-phase of H. capsulatum and P. brasiliensis were studied by means of scanning and transmission electron microscopy. The observed alterations on both fungi were very similar to those induced by the same drug on the ultrastructure of C. albicans. These alterations include surface changes, abnormal membrane proliferation, fatty degeneration of the cytoplasm and lysis of the subcellular organelles. P. brasiliensis seems to be more sensitive to ketoconazole than H. capsulatum, since the necrosis of most of the cells was obtained in the former at a concentration of 0.1 microgram/ml and in the latter at 1 microgram/ml.

Cell Membrane↗