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Biomedical subjects

S Hyde

Publications and source records attributed to S Hyde.

28 records · Page 2Linked to original sources
PubMed1989

Translational coupling in the threonine operon of Escherichia coli K-12.

In an attempt to express the two distal genes of the Escherichia coli threonine operon, the majority of the first gene in the operon, thrA, was removed and a series of transcriptional fusions were constructed placing the thrB and thrC genes downstream of either the trp or hybrid tac promoter. Analysis of the proteins produced by cells containing these fusions revealed that although the distal gene, thrC, was efficiently expressed, the proximal gene, thrB, was not expressed at a detectable level. A translational fusion was constructed which fused the cat gene in phase to the last 800 base pairs of thrA followed by thrB and thrC. Cells containing this fusion produced high levels of both the thrB and thrC gene products, showing that translation of thrB requires translation through thrA; thus, thrA and thrB are translationally coupled. In addition, it was found that a sequence between 220 and 57 base pairs before the start of thrB was necessary to allow translational coupling to occur.

Carbon-Oxygen Lyases↗
PubMed1989

Meconium-induced vasocontraction: a potential cause of cerebral and other fetal hypoperfusion and of poor pregnancy outcome.

Chronically meconium-stained fetuses may ultimately suffer cerebral palsy and other devastation. The mechanism is unknown. Innocuous pregnancy complications may cause some fetuses to discharge meconium, which may become hazardous, independently of aspiration. We herein report previously undescribed, meconium-induced umbilical and placental vascular necrosis. To investigate whether meconium causes vasocontraction, we tested umbilical vein tissue with an isometric transducer connected to a polygraph. The specimens were suspended in a 30-mL organ bath with Krebs solution (pH, 7.4; temperature, 37 degrees C; under aeration with 95% O2 and 5% CO2). We exposed the tissue to meconium and compared meconium-induced vasocontraction with that induced by Krebs solution and 10(-5) molar serotonin. Meconium maximally produced 62.9% of serotonin-induced vasocontraction. Krebs solution and boiled meconium did not produce vasocontraction. We hypothesize that meconium may cause placental and umbilical cord vasocontraction, cerebral and other fetal hypoperfusion, and major poor outcome.

Asphyxia Neonatorum↗
PubMed1988

Clinicopathologic considerations of fusobacteria chorioamnionitis.

When sought by light microscopy in formalin-fixed tissue, fusobacteria are apparent in 7-18% of chorioamnionitis cases. Brown and Hopps bacterial staining characteristically visualizes their long, slender and filamentous forms. Fusobacteria-like organisms in placentae have previously been associated with prematurity. Our findings indicate that perinatal infection with fusobacteria may cause neonatal death from prematurity, rather than from sepsis. In a study of 586 placentae, 14 specimens with chorioamnionitis and fusobacteria-like organisms were found. On the five occasions when microbiologic tests were made, fusobacteria were isolated. Prematurity of the newborns was associated with twelve of those placentae. Immunofluorescent labelling of the organisms is a helpful but incomplete means of diagnosis. Because fusobacteria antibodies are highly specific, they do not cross-react with other members of the genus Fusobacterium. A typical case is reported, in detail.

Adult↗
PubMed1985

Fusobacteria. An important cause of chorioamnionitis.

Prematurity is the main cause of human perinatal disease and chorioamnionitis is the main cause of prematurity. The diverse etiologic role of infection is incompletely known. Fusobacteria (FB) are herein reported to be delineated by the Warthin-Starry (WS) stain; an animal model was developed to reinforce evidence that FB cause chorioamnionitis. Isolates of these bacteria from three human placentas were inoculated into rabbits to develop antisera. Within an annual study of 297 human placentas, 138 were processed with WS stains. By WS stain, microbiologic culture, and immunofluorescent labelling of three placentas, FB were proved to cause chorioamnionitis. Sixty-two (35%) of 176 premature newborns had chorioamnionitis. Of these 62, 11 (18%) had morphologically evident FB; FB-like organisms were associated with chorioamnionitis and prematurity. Our findings support and expand clinical investigation of the amniotic infection syndrome.

Animals↗
PubMed1984

Analysis of the acid phosphatases of rat sensory ganglia by isoelectric focussing on polyacrylamide gels.

The acid phosphatases of rat spinal and trigeminal ganglia have been separated by isoelectric focussing on polyacrylamide gels into two main classes with pI's of 7.1 and 5.4. A low-pI acid phosphatase is also present in the mouse but not in the guinea pig. Evidence is presented that in the rat the pI 5.4 enzyme represents the nonlysosomal acid phosphatase that has been identified histochemically in one population of sensory neurones. This pI 5.4 acid phosphatase is partly membrane-bound and is selectively depleted by capsaicin administration. In lumbar dorsal root ganglia the enzyme is selectively depleted by sectioning the sciatic nerve and undergoes rapid axonal transport, a greater amount being transported peripherally than centrally. The results are discussed with reference to the possible function of this nonlysosomal acid phosphatase.

Acid Phosphatase↗
PubMed1975

Effect of diuretics on oxidative phosphorylation of dog kidney mitochondria.

An effect of diuretics on cellular metabolism has been shown. In order to examine further the direct effect of diuretics on renal mitochondria, their effect on isolated cortical (C) and outer medullary (OM) mitochondrial respiration was examined. Oxygen consumption rate (QO2) was measured in a Gilson oxygraph utilizing either glutamate-malate or succinate as substrate. QO2, expressed in nanoatoms of O2 per milligram of protein per minute, was always higher in C than OM: 140.7 +/- 2.8 VS. 121.2 +/- 2.4 (P less than 0.001) with glutamate-malate and 181.1 +/- 6.3 vs. 129.7 +/- 5.2 (P less than 0.001) with succinate. A dose-response curve was constructed for each of the following: sodium ethacrynate, furosemide, chlorothiazide, acetazolamide and chlormerodrin. All diuretics inhibited C and OM equally. The 50% inhibitory molar concentration for EA was 6.2 times 10(-4); for furosemide 1.5 times 10(-3); for chlorothiazide 8.1 times 10(-3); for acetazolamide 10.8 times 10(-3); and for chlomerodrin 3.1 times 10(-5). Neither cysteine nor dithiothreitol inhibited the effect of EA. The effect of chlormerodrin was abolished by cysteine. These results demonstrate that while a difference exists between C and OM mitochondria during control studies, each of the diuretics examined exerted an equal inhibitory effect on mitochondrial respiration from both C and OM. Mercurials are the most potent inhibitors and presumably exert their effect by reacting with sulfhydryl groups. They are followed in potency by ethacrynic acid, furosemide, chlorothiazide and acetazolamide.

Animals↗