Localization of hydrogenase in the purple sulphur bacterium Thiocapsa roseopersicina

The localization of hydrogenase in the phototrophic bacterium Thiocapsa roseopersicina was investigated by subcellular fractionations, and transmission electron microscopic immunocytochemistry. By using sonicated cells and measuring in vitro hydrogenase activities in soluble and membrane fractions, respectively, a weak hydrophobic interaction between the hydrogenase enzyme and the T. roseopersicina membranes was observed. Polyclonal antisera directed against the purified hydrogenase were raised in rabbits and exhibited one band in native-PAGE/Western immunoblot analysis. Native-PAGE/activity stain confirmed the identity of this band as being hydrogenase. Immunocytolocalization experiments using ultrathin sections showed an internal localization of the hydrogenase enzyme. A higher specific labeling was associated with chromatophores, indicating a possible coupling of hydrogenase with the photosynthetic membranes in the T. roseopersicina cells.     

Induction of H2-Uptake and Nitrogenase Activities in the Cyanobacterium Anabaena variabilis ATCC 29413: Effects of Hydrogen and Organic Substrate

A comparative study of the development of uptake hydrogenase and nitrogenase activities in cells of the cyanobacterium Anabaena variabilis was performed. The induction of heterocysts is followed by the induction of both in vivo hydrogen uptake and nitrogenase activities. Interestingly, a low but significant H₂-uptake [2–7 μmoles of H₂ · mg⁻¹ (Chl a) · h⁻¹] occurs in cultures with no heterocysts and with no nitrogenase activity. A slight stimulatory effect (30–40%) of H₂ on in vivo H₂-uptake was observed during the early stages of nitrogenase induction. However, exogenous H₂ does not further stimulate the induction of in vivo hydrogen uptake observed during heterocyst differentiation. Similarly, organic carbon (fructose) did not influence the induction of either in vivo hydrogen uptake or nitrogenase activities. Exogenous fructose supports higher in vivo hydrogen uptake and nitrogenase activities when the cells enter late exponential phase of growth. Received: 22 November 1995 / Accepted: 22 December 1995     

GM1 ELISA method for demonstration of Escherichia coli heat-stable enterotoxin

Abstract A GM1-ELISA for detection of the methanol soluble, heat-stable enterotoxin (ST_a) produced by many enterotoxinogenic E. coli strains has been developed. This ST-GM1-ELISA, which is based on inhibition of binding of anti-ST antibody to GM1-bound ST-cholera B subunit conjugates, is relatively simple and possible to perform with stable reagents and without any complicated equipment. By this method ST_a could be detected in culture filtrates of human E. coli isolates with 100% sensitivity and specificity. The sensitivity of the method for purified ST is considerably higher than that of the conventional infant mouse test and comparable to that of recently described radioimmunoassays for ST.     

Control of blood pressure and risk of first acute myocardial infarction: Skaraborg hypertension project.

OBJECTIVE--To analyse the relation between treated blood pressure and concomitant risk factor and morbidity from acute myocardial infarction. DESIGN--Prospective longitudinal study. Treated blood pressures and other variables were used to predict acute myocardial infarction. SETTING--Primary health care in Skaraborg, Sweden. SUBJECTS--1121 men and 1453 women aged 40-69 years at registration at outpatient clinics, 1977-81, with no evidence of previous myocardial infarction were followed up for an average of 7.4 years. Subjects were undergoing treatment with drugs to lower blood pressure or had blood pressure that exceeded the systolic or diastolic limits, or both, for diagnosis (> 170/> 105 mm Hg (patients aged 40-60 years) and > 180/> 110 mm Hg (older than 60 years)) on three different occasions, or both. MAIN OUTCOME MEASURES--First validated event of fatal or non-fatal acute myocardial infarction. RESULTS--In men but not in women there was a negative relation between treated diastolic blood pressure and risk of acute myocardial infarction. Left ventricular hypertrophy and smoking were contributory risk factors in both sexes, as was serum cholesterol concentration in men. In men with normal electrocardiograms (n = 345) risk increased with increasing diastolic blood pressure (P = 0.047), whereas the opposite was found in men with electrocardiograms suggesting ischaemia or hypertrophy, or both (n = 499, P = 0.009). In those with a reading of 95-99 mm Hg the relative risk was 0.30 (P = 0.034); at > or = 100 mm Hg it was 0.37 (P = 0.027). No similar relations were seen in women or for systolic blood pressure. CONCLUSION--It may be hazardous to lower diastolic blood pressure below 95 mm Hg in hypertensive men with possible ischaemia or hypertrophy, or both. Electrocardiographic findings should be considered when treatment goals are decided for men with hypertension.