Regulation of hydrogen metabolism in Butyribacterium methylotrophicum by substrate and pH

 Exogenous H₂/CO₂ and glucose were consumed simultaneously by Butyribacterium methylotrophicum when grown under glucose-limited conditions. CO₂ reduction to acetate was coupled to H₂ consumption. The addition of either H₂ or CO₂ to glucose batch fermentation resulted in an increase in cell density, hydrogenase (H₂-consuming and -producing) activities and fatty acid production by B. methylotrophicum as compared to when N₂ was the feed gas. Hydrogenase activities appeared to be tightly regulated and were produced at higher rates during the exponential phase when CO₂ was the feed gas as compared to H₂ or N₂. The increase in H₂-consuming activity and decrease in H₂-producing activity was correlated with an increase in butyrate synthesis. H₂-consuming and ferredoxin (Fd)–NAD reductase activities increased while H₂-producing and NADH–Fd reductase activities decreased in cells grown at pH 5.5 compared to those at pH 7.0. The molar ratio of butyrate/acetate was shifted from 0.35 at pH 7.0 to 1.22 at pH 5.5. The addition of exogenous H₂ did not decrease the butyrate/acetate ratio at pH 7.0 nor at pH 5.5. The results indicated that growth pH values regulated both hydrogenase and Fd–NAD oxidoreductase activities such that, at acid pH, more intermediary electron flow was directed towards butyrate synthesis than H₂ production. Received: 22 August 1995/Received revision: 18 December 1995/Accepted: 22 January 1996     

Serum lipids and lipoprotein abnormalities in patients with thrombotic stroke--with exploring the protective role of HDL subfractions

The main purpose of this report is to demonstrate the presence of subfractions in serum HDL and to explore their role in the pathogenesis of thrombotic stroke Preparative untracentrifugation was used to isolate the differing density fractions of serum lipoproteins, and 2-27% polyacrylamide gradient gel electrophoresis was used to identify the character of the HDL subfractions. The study was performed on 59 Chinese males, in whom 31 were patients with thrombotic stroke affecting the cerebral cortex diagnosed by neurological examination and computed tomography; and the others grouped as healthy control. The age and Broca index of both groups were similar. The serum levels of total cholesterol and LDL-cholesterol were normal. However, in the thrombotic stroke group HDL-cholesterol was significantly lower and correlated inversely with both significantly higher levels of VLDL-cholesterol (r=-0.5392, p less than 0.01) and VLDL-triglyceride (r=-0.5866, p less than 0.01). The serum levels of total triglycerides and LDL-triglyceride were also significantly higher in patient with thrombotic stroke. The mean area percentage of HDL2b subfraction measured in the diameter range as determined by gradient gel electrophoresis was significantly lower and HDL2 also showed the same tendency in patients with thrombotic stroke. Our finding was consistent with the postulation that HDL2 or HDL2b in in particular, probably played a more protective role than any other HDL subfractions against thrombotic stroke, one of the major atherosclerotic complications.     

Vibrio nitrifigilis sp. nov., a marine nitrogen-fixing bacterium isolated from the lagoon sediment of an islet inside an atoll

A nitrogen-fixing isolate of facultatively anaerobic, marine bacterium, designated strain NFV-1^T, was recovered from the lagoon sediment of Dongsha Island, Taiwan. It was a Gram-negative rod which exhibited motility with monotrichous flagellation in broth cultures. The strain required NaCl for growth and grew optimally at about 25–35 °C, 3% NaCl and pH 7–8. It grew aerobically and could achieve anaerobic growth by fermenting d-glucose or other carbohydrates as substrates. NH₄Cl could serve as a sole nitrogen source for growth aerobically and anaerobically, whereas growth with N₂ as the sole nitrogen source was observed only under anaerobic conditions. Cellular fatty acids were predominated by C_16:1 ω7c, C_16:0, and C_18:1 ω7c. The major polar lipids consisted of phosphatidylethanolamine and phosphatidylserine. Strain NFV-1^T had a DNA G?+?C content of 42.5 mol%, as evaluated according to the chromosomal DNA sequencing data. Analyses of sequence similarities and phylogeny based on the 16S rRNA genes, together with the housekeeping genes, gyrB, ftsZ, mreB, topA and gapA, indicated that the strain formed a distinct species-level lineage in the genus Vibrio of the family Vibrionaceae. These phylogenetic data and those from genomic and phenotypic characterisations support the establishment of a novel Vibrio species, for which the name Vibrio nitrifigilis sp. nov. (type strain NFV-1^T?=?BCRC 81211^T?=?JCM 33628^T) is proposed.

     

Natural history of coronary artery disease in relation to angiographic, hemodynamic and clinical factors

Studying the natural history of coronary artery disease could provide a frame of reference for prognosis and appraisal of treatment for patients having this disease. We studied a total of 465 consecutive patients with angiographically significant coronary artery disease, defined as greater than 50% stenosis in at least one principal artery, who were followed with medical treatment only from 1 to 7 years. Excluding patients with left main coronary disease, there were 73 deaths, of whom 63 were cardiac. The 5-year cumulative survival rates were 72% for the entire group, 87% for single vessel disease, 73% for double vessel disease and 51% for triple vessel disease. In single vessel disease, patients with left anterior descending artery involvement tended to have higher mortality. In double vessel disease, survival was worse with the combination of left anterior descending and right coronary artery involvements than the other 2 combinations. A history of myocardial infarction was not significantly different from angina in 5-year survival rate. Nevertheless, an abnormal Q-wave in ECG was associated with lower survival. History of hypertension and electrocardiographic left ventricular hypertrophy did not affect survival. While congestive heart failure, abnormal resting LVEDP and left ventricular asynergy were all associated with reduced survival. The left ventricular ejection fraction had highly prognostic value, only 42% of patients survived with ejection fraction less than 0.3 at the end of 5 years after angiography.     

Expanisns

Biochemical dissection of the “acid-growth” process of plant cell walls led to the isolation of a new class of wall loosening proteins, called expansins. These proteins affect the rheology of growing walls by permitting the microfibril-matrix network to slide, thereby enabling the wall to expand. Molecular sequence analysis suggests that expansins might have a cryptic glycosyl transferase activity, but biochemical results suggest that expansins disrupt noncovalent bonding between microfibrils and the matrix. Recent discoveries of a new expansin family and gene expression in fruit, meristerms and cotton fibers have enlarged our view of the developmental functions of this group of wall loosening proteins.