Catalytic activity of the chromophore of desulfoviridin, sirohydrochlorin, in sulfite reduction in the presence of iron

Sirohydrochlorin chromophore prepared by acetone/HCl treatment of desulfoviridin, the sulfite reductase from Desulfovibrio, catalyzed the reduction of sulfite to sulfide and thiosulfate in equimolar amounts when coupled with a hydrogen-hydrogenase-methyl viologen system. This activity was manifested at acidic pH and increased exponentially with decrease in pH. The Km value for sulfite was nearly 10 times that of desulfoviridin. Inorganic iron was necessary for the reduction, since inactivation occurred on passage through a Sephadex LH-20 column or in the presence of 2,2'-bipyridine, and reactivation was observed on adding iron. The chromophore catalyzed the reduction of dithionite and hyroxylamine.

A possible intraneuronal site of action of thymoleptics

The uptake of catecholamines (CAs) into crude mitochondria preparations (P2 fractions) and vesicle preparations from rat hypothalamus and striatum were compared in terms of the inhibition by thymoleptics and other drugs. Thymoleptics preferentially inhibited the uptake of CAs into hypothalamic P2 fractions, while ATPase inhibitors preferentially inhibited the uptake of dopamine into striatal P2 fractions. When the preparation obtained from rats pretreated with reserpine was used, the preferential inhibition of hypothalamic uptake by thymoleptics was entirely abolished. When P2 fractions from both regions were incubated with 10(-6) M 14C-imipramine, the intrasynaptosomal distribution of labeled imipramine revealed its affinity not only to the synaptosomal membrane, but also to the synaptic vesicles. Accumulated 3H-norepinephrine (NE) could be released by a hypoosomotic shock from striatal P2 fractions, but not from hypothalamic P2 fractions. The ATP-Mg2+-dependent uptake of 3H-NE into the synaptic vesicles from rat brain stem was inhibited by desipramine. These results indicate that the inhibition of CA uptake by thymoleptics in the hypothalamus is predominantly due to the inhibition at the synpatic vesicle, while in the striatum the uptake at the synaptosomal membrane is predominantly inhibited.

Biochemical studies on sulfate-reducing bacteria. XV. Separation and comparison of two forms of desulfoviridin

Desulfoviridin from Desulfovibrio vulgaris was separated into two forms by DEAE-Sephadex column chromatography. The major form had a pI of 4.4 and the minor form one of 4.5-4.6. Both forms produced mainly trithionate, besides thiosulfate and sulfide, in methylviologen-linked sulfite reduction. The specific activities of sulfite reduction, as well as of hydroxylamine reduction, were virtually identical in both forms. There were no great differences in their absorption spectra, CD spectra, molecular weights, subunit compositions, labile sulfide, and iron contents, and amino acid compositions. The N-terminal amino acid was alanine in both forms.

Cytologic features of primary leiomyosarcoma of the lung. Report of a case diagnosed by bronchial brushing procedure

This is a case report of a 19-year old woman with primary leiomyosarcoma of the lung. The tumor was successfully diagnosed by the bronchial brushing method under fluoroscopic guidance. Cellular features of the leiomyosarcoma are described in detail.

Carcinoma of the cystic duct: case report

A case of carcinoma of the cystic duct is presented and comprehensive review of the literature was provided. Since no characteristic clinical signs are present, the diagnosis can only be made incidentally at the time of laparotomy for non-visualizing gallbladder. Even then histological study of the resected specimen is mandatory. In our present case after the confirmation of the diagnosis the second look exploration was done. However, careful examination of the bile duct system failed to find evidence of carcinomatous involvement suggesting that carcinoma found in the cystic duct was of a primary and not a secondary invasion. The present case constitutes the nineteenth case which meets completely the criteria proposed by Farrar. Since the only hope or cure lies with the early diagnosis of the disease, early exploratory laparotomy and prophylactic removal of nonfunctioning or calculous gallbladder are recommended.