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At least 1,171 records · Page 65Linked to original sources
PubMed1978

Production of branched-chain volatile fatty acids by certain anaerobic bacteria.

Net production of isobutyric acid, isovaleric acid, and 2-methylbutyric acid by cultures of Bacteroides ruminicola and Megasphaera elsdenii on media that contained Trypticase or casein hydrolysate continued (up to 5 days) after growth had ceased. Only trace quantities of these acids were produced in a medium that contained a mixture of amino acids that did not include the branched-chain amino acids. M. elsdenii produced increased quantities of the branched-chain fatty acids in a medium that contained Trypticase when glucose was reduced or eliminated from the culture medium. However, B. ruminicola produced increased quantities of branched-chain fatty acids and of phenylacetic acid from Trypticase when glucose was supplied at 3 mg/ml rather than at 1 mg/ml. Single strains of Streptococcus bovis, Selenomonas ruminantium, Bacteroides amylophilus, and Butyrivibrio fibrisolvens did not produce branched-chain fatty acids.

Anaerobiosis↗
PubMed1973

Nutritional alteration of the fatty acid composition of a thermophilic Bacillus species.

The fatty acid composition of a thermophilic Bacillus sp. was altered by the addition of isobutyrate, isovalerate, alpha-methylbutyrate, leucine, and isoleucine to the growth medium. With isobutyrate, 81% of the fatty acids had 16 carbon atoms and 79% were iso-fatty acids with an even number of carbon atoms. With leucine, 58% of the fatty acids had 15 carbon atoms and 86% were iso-fatty acids with an odd number of carbon atoms. With isoleucine, 72% of the fatty acids had 17 carbon atoms and 88% were anteiso-fatty acids with an odd number of carbon atoms. Thus, by altering the composition of the growth medium, cells were produced in which the majority of the fatty acids had either 15, 16, or 17 carbons and belonged to each of the three groups of branched-chain fatty acids. The wide variation observed in the fatty acid composition makes it unlikely that any specific branched-chain fatty acid is required for vital functions.

Acetates↗
PubMed1975

Leucine biosynthesis in the blue-green bacterium Anacystis nidulans.

Leucine-requiring auxotrophs of the unicellular blue-green bacterium Anacystis nidulans have been isolated. Extracts of these mutants were deficient in alpha-isopropylmalate synthetase (EC 4.1.3.12). In wild-type cells, this enzyme was subject to feedback inhibition by leucine. However, formation of the enzymes of leucine biosynthesis was little affected by exogenous leucine in either wild-type or mutant strains. Cultures of the latter subjected to extreme leucine deprivation showed no change in specific activity of beta-isopropylmalate isomerase (EC 4.2.1.33) and at most a 50% increase in the specific activity of beta-isopropylmalate dehydrogenase (EC 1.1.1.85). These results are compared with others bearing on the evolution of the control of amino acid biosynthesis in blue-green bacteria.

2-Isopropylmalate Synthase↗
PubMed1967

Biosynthesis of alpha-isopropylmalic and citric acids in Acetobacter suboxydans.

Cell-free extracts of Acetobacter suboxydans were prepared which were capable of condensing alpha-ketoisovalerate with (14)C-labeled acetyl-coenzyme A to yield (14)C-labeled alpha-isopropylmalate. The product of the reaction was isolated by paper and column chromatography and was characterized by recrystallization with synthetic alpha-isopropylmalic acid to constant specific radioactivity. The formation of alpha-isopropylmalate by extracts of A. suboxydans plus the ability of the organism to grow in a simple glucose-glycerol medium containing glutamic acid as the only amino acid indicate that the pathway for leucine biosynthesis shown to exist in yeast and Salmonella typhimurium also occurs in A. suboxydans. As a comparison, the condensation of oxalacetate and ((14)C) acetyl-coenzyme A to yield ((14)C) citric acid was shown, by similar means, to occur in A. suboxydans. This is of interest since the existence of this classical condensing enzyme has hitherto not been demonstrated in this organism. This reaction was further demonstrated in cell-free extracts of A. suboxydans by means of a spectrophotometric assay at 232 mmu which measured the cleavage of the carbon-sulfur bond of acetyl-coenzyme A in the presence of oxalacetate. Comparison of the specific activities of crude cell-free extracts indicated a much more extensive occurrence of this reaction in yeast than in A. suboxydans.

Acetobacter↗
PubMed1984

Siderophore production by Proteus mirabilis.

Studies on the isolation and characterization of Proteus mirabilis siderophores provided no evidence that these bacteria synthesize catechol- or hydroxamate-type siderophores. However, gas chromatograph analysis in conjunction with mass spectroscopy revealed the presence of alpha-hydroxyisovaleric acid, a previously unknown metabolite. Additional substantiating evidence for the presence of alpha-hydroxyisovaleric acid in these bacteria was obtained from experiments involving the use of thin-layer chromatography and an ultraviolet absorption spectrum. This compound was found to be capable of removing iron from the synthetic chelator, ethylene-diamine-di-orthohydroxyphenyl acetic acid, and supplying that iron to the bacteria both in a solid agar medium and in a liquid medium. Proteus mirabilis was found to possess an enzyme capable of catalyzing the reaction by which alpha-hydroxyisovaleric acid is converted to alpha-ketoisovaleric acid, an intermediate in the valine biosynthetic pathway.

Animals↗
PubMed1975

Production of the features of Reye's syndrome in rats with 4-pentenoic acid.

4-Pentenoic acid, an analog of hypoglycin which is believed to cause Jamaican vomiting sickness, was administered intraperitoneally to rats in an attempt to produce the features of Reye's syndrome in rats. Mean ammonia levels in plasma were found to be elevated approximately four-fold after injection of 200 mg/kg pentenoic acid in fed rats. Pentenoic acid caused hypoglycemia in fasted rats and hyperglycemia in fed rats. In chronic experiments rats were injected intraperitoneally every 4 hr with 50 mg/kg body weight of pentenoic acid for 10 doses, followed by a single dose of 200 mg/kg. The livers of the treated group were enlarged and yellow and showed extensive fatty degeneration. The blood-urea-nitrogen (BUN) was significantly higher and the free fatty acids (FFA's) significantly lower in these rats. This study shows that pentenoic acid administered to rats produces findings similar to those of Reye's syndrome and Jamaican vomiting sickness.

Ammonia↗
PubMedDate not supplied

Tazarotene cream (0.1%) in combination with betamethasone valerate foam (0.12%) for plaque-type psoriasis.

A combination of multiple agents is often required to achieve treatment success for plaque-type psoriasis. We report a case series of 10 patients that were treated with betamethasone valerate foam (0.12%) in the morning and topical tazarotene cream (0.1%) in the evening for a total of 12 weeks or until plaques cleared. Erythema, scale, and thickness along with an aggregate severity score were determined at weeks 4, 8, and 12. One patient was lost to follow-up. Eight of the other 9 patients experienced improvement in their disease by week 12. Two patients were clear of their psoriasis at week 4 and 4 were clear at week 8. No adverse events, including irritation were reported; the use of the corticosteroid foam may protect against potential local irritation reported with tazarotene. The combination of tazarotene cream and betamethasone valerate foam is an effective combination approach to treating localized plaque-type psoriasis.

Betamethasone Valerate↗
PubMed1990

[Antianaphylactic components of Asarum forbsii Maxin].

From the ethyl acetate extract of Asarum forbesii Maxin, four new constituents, asarumin A(I), B(II), C(III) and D(IV), were isolated along with elemicin (V), trans-asarone(VI) and linoleic acid(VII). The structures of the new compounds were elucidated as methyl 3 S-benzoyloxy-2 S-hydroxy-2-isopropylbutyrate for I, methyl 2 R-benzoyloxyisopentanoate for II, methyl 2 R-trans-cinnamoyloxyisopentanoate for III and methyl 2 R-piperonyloyloxyisopentanoate for IV. Compounds I, II, III and VII showed weak inhibition of PCA in rats, but the other compounds were inactive.

Animals↗