Production of enterotoxin A by supposedly nonenterotoxigenic Staphylococcus aureus strains

The production of staphylococcal enterotoxins A (SEA) and B (SEB) was studied by inoculating six well-defined staphylococcal collection strains into cow's, goat's, or sheep's milk (individually or as a 50% mixture of cow's + goat's or cow's + sheep's), into brain heart infusion, and into a medium generally used to enhance the synthesis of enterotoxins (3+3 medium). Four of the strains used are considered to be SEB producers, another is considered an SEA producer, and the remaining strain is nonenterotoxigenic but produces large quantities of staphylococcal protein A. Staphylococcal protein A masked the results in most cases. Only one strain secreted exclusively SEB, while the other three SEB producers synthesized SEA in different amounts. We conclude that enterotoxin production depends on the natural substrate and may differ from the results obtained when the strain is grown on cellophane over agar to determine its toxigenicity.     

O dealkylation and aliphatic and aromatic hydroxylation of 3-methoxy-17 beta-estradiol by Aspergillus alliaceus

Aspergillus alliaceus UI 315 was examined for its ability to metabolize 3-methoxy-17 beta-estradiol. Preparative-scale incubations with this substrate afforded good yields of 6 beta-hydroxy-17 beta-estradiol, 4-hydroxy-17 beta-estradiol, and 4,6 beta-dihydroxy-17 beta-estradiol, which were identified by high-pressure liquid chromatography, 1H and 13C nuclear magnetic resonance, and high-resolution mass spectrometry.     

Cloning and sequencing of the peroxisomal amine oxidase gene from Hansenula polymorpha

We have cloned the AMO gene, encoding the microbody matrix enzyme amine oxidase (EC 1.4.3.6) from the yeast Hansenula polymorpha. The gene was isolated by differential screening of a cDNA library, immunoselection, and subsequent screening of a H. polymorpha genomic library. The nucleotide sequence of a 3.6 kilobase stretch of DNA containing the amine oxidase (AMO) gene was determined. The AMO gene contains an open reading frame of 692 amino acids, with a relative molecular mass of 77,435. The 5' and 3' ends of the gene were mapped and show that the transcribed region measures 2134 nucleotides. The derived amino-acid sequence was confirmed by sequencing an internal proteolytic fragment of the purified protein. Amine oxidase contains the tripeptide sequence Ser-Arg-Leu, located 9 residues from the carboxy terminus, which may represent the topogenic signal for protein import into microbodies.     

O dealkylation and aliphatic and aromatic hydroxylation of 3-methoxy-17 beta-estradiol by Aspergillus alliaceus.

Aspergillus alliaceus UI 315 was examined for its ability to metabolize 3-methoxy-17 beta-estradiol. Preparative-scale incubations with this substrate afforded good yields of 6 beta-hydroxy-17 beta-estradiol, 4-hydroxy-17 beta-estradiol, and 4,6 beta-dihydroxy-17 beta-estradiol, which were identified by high-pressure liquid chromatography, 1H and 13C nuclear magnetic resonance, and high-resolution mass spectrometry.     

Production of enterotoxin A by supposedly nonenterotoxigenic Staphylococcus aureus strains.

The production of staphylococcal enterotoxins A (SEA) and B (SEB) was studied by inoculating six well-defined staphylococcal collection strains into cow's, goat's, or sheep's milk (individually or as a 50% mixture of cow's + goat's or cow's + sheep's), into brain heart infusion, and into a medium generally used to enhance the synthesis of enterotoxins (3+3 medium). Four of the strains used are considered to be SEB producers, another is considered an SEA producer, and the remaining strain is nonenterotoxigenic but produces large quantities of staphylococcal protein A. Staphylococcal protein A masked the results in most cases. Only one strain secreted exclusively SEB, while the other three SEB producers synthesized SEA in different amounts. We conclude that enterotoxin production depends on the natural substrate and may differ from the results obtained when the strain is grown on cellophane over agar to determine its toxigenicity.     

Chronic measurement, using a Doppler probe, of uterine artery flow in the gravid guinea-pig

A chronic animal model is described which permits for the first time the continuous measurement of uterine artery blood flow velocity in the pregnant guinea-pig by using a miniaturized Doppler flow probe. Preliminary validation revealed that alterations in actual blood flow are directly and proportionally related to the change in the Doppler shift (r = 0.984) from 0 to 100 ml/h. The velocity signal baseline was as stable as that of systemic blood pressure. Depending upon the individual animal's flow velocity, a deviation of 2-5% from baseline was statistically significant. With experience, greater than 90% of preparations were successful and a 30-day interval was often available for study. Uterine artery flow velocity increased steadily between 45 and 55 days of gestation. Instrumentation did not result in fetal growth retardation. A reduction in flow velocity occurred during general anaesthesia using ketamine and the antianxietal xylazine. In agreement with the reports of other investigators using a different model, both hydralazine and angiotensin II increased uterine blood velocity and adrenaline reduced it.     

Electron microscopic and histochemical characterization of intra-arterial cushions of the rat and porcine uterine vascular bed

Scanning and transmission electron microscopic studies, together with histochemical investigations, were conducted on rat and porcine intra-arterial cushions from the uterine vascular bed. In the rat, the fine structure of these cushions closely resembled that previously described in the rat kidney. The cushions were composed of modified smooth muscle, circularly disposed in an incomplete, raised band surrounding the entrance to arterial branches. These muscle cells projected as attenuated processes throughout the loosely organized, PAS-positive stroma, and established close contact with thin endothelial extensions projecting from the base of the surface endothelial cells. Scanning electron microscopic observations of furrows on the endothelial surface gave rise to the suggestion that such contacts might mediate muscular control of endothelial surface topology. In similar cushions from the pig uterine artery, the smooth muscle of the cushions was much more compactly organized, and was disposed radially, rather than circumferentially, within the cushion structure. The enzyme histochemical profile of porcine cushions did not differ appreciably from that of normal vascular smooth muscle and endothelium, suggesting the maintenance of a metabolic similarity with adjacent tissues. These studies clarify the fine-structural basis for recently reported contraction and relaxation of uterine artery cushions during ischemia and perfusion of the rat uterine vascular bed, and thus, for their functional role in the regulation of uterine vascular flow.     

Enterotoxin production by staphylococci isolated from healthy goats

The ability of 342 staphylococcal isolates from different anatomical sites in healthy goats to produce staphylococcal enterotoxins (SE) was investigated. SE were produced by 74.3% of the 70 coagulase-positive strains and by 22% of the coagulase-negative strains studied. Most enterotoxigenic strains were isolated from the skin of udders and teats and from milk. SEC was the SE type most frequently produced, either alone (67.9%) or in combination with others. Five coagulase-negative species not previously reported as SE producers were identified (Staphylococcus chromogenes, S. warneri, S. sciuri, S. saprophyticus, and S. lentus). SEA, SEB, and SEC were detected in the milk of 17 of the 133 healthy goats studied. These results suggest that the goat is an important reservoir of enterotoxigenic staphylococci, most of which produce SEC.     

Enterotoxin production by staphylococci isolated from healthy goats.

The ability of 342 staphylococcal isolates from different anatomical sites in healthy goats to produce staphylococcal enterotoxins (SE) was investigated. SE were produced by 74.3% of the 70 coagulase-positive strains and by 22% of the coagulase-negative strains studied. Most enterotoxigenic strains were isolated from the skin of udders and teats and from milk. SEC was the SE type most frequently produced, either alone (67.9%) or in combination with others. Five coagulase-negative species not previously reported as SE producers were identified (Staphylococcus chromogenes, S. warneri, S. sciuri, S. saprophyticus, and S. lentus). SEA, SEB, and SEC were detected in the milk of 17 of the 133 healthy goats studied. These results suggest that the goat is an important reservoir of enterotoxigenic staphylococci, most of which produce SEC.