Effects of dietary vitamin B-2 and vitamin E on the delta9-desaturase and catalase activities in the rat liver microsomes.

The effects of dietary vitamin B-2 and vitamin E on delta9-desaturation of stearoyl-CoA, catalase, glutathione peroxidase, superoxide dismutase and electron transport components in rat liver microsomes have been investigated. delta9-desaturase activities were decreased on diets deficient of vitamin B-2, E and supplemented with E. Among the peroxide-scavenging enzymes, only the catalase activity in microsomes correlates significantly with delta9-desaturase activity. In vitro addition of bovine catalase had no effect on microsomal delta9-desaturase activity on control diet. However, it enhanced the delta9-desaturation in microsomes on vitamin B-2-deficient diet which contained low catalase and high superoxide dismutase activities, compared to those in microsomes of control diet. It is suggested that the hydrogen peroxide-generating and -decomposing systems may play an important role on the delta9-desaturase activity in microsomes.     

Transport of Tricarboxylic Acids in Salmonella typhimurium

Salmonella typhimurium possesses at least three inducible transport systems for the tricarboxylic acids (citric, isocitric, cis-aconitic, and tricarballylic). The first system was induced by citrate, isocitrate, or cis-aconitate, and transported citric acid and isocitric acid. The second system was also induced by the same acids as in the first system and transported cis-aconitic acid. This system required Mg(2+) ions and was stable at pH 8.4 but unstable at pH 7.0. The metal ion was replaced with Sr(2+) or Ca(2+) ions but not with Ba(2+) ions. The third system was induced by tricarballylate and transported citric acid, cis-aconitic acid, and tricarballylic acid.     

Slowness of blood flow and resultant thrombus formation in cerebral aneurysms

It is not yet fully understood what causes cerebral aneurysms to rupture. Although no definitive conclusion has been reached, it is considered that there are haemodynamic, biochemical and physiological factors contributing to rupture. Numerical techniques seem promising for investigation of this multi-physical phenomenon. In fact, recent intensive numerical studies with computational fluid dynamics have revealed detailed haemodynamic features of the flow in cerebral aneurysms such as velocity, pressure and wall shear stress distributions. It is, therefore, expected that biochemical and physiological aspects of aneurysmal rupture will also be actively investigated using numerical approaches. Considering this background, the authors have been working on modelling of thrombus formation in cerebral aneurysms caused by stagnant blood flow, because many studies have suggested that slow blood flow and resulting low wall shear stress are connected with rupture. Firstly, in this review paper, slowness of the intra-aneurysmal flow is reviewed with an energy balance theory, and secondly, thrombus formation in cerebral bifurcation aneurysms is discussed from the viewpoint of numerical modelling. A computational result obtained by application of the authors’ platelet aggregation–adhesion model is also provided.     

Direct human T helper cell-induced B cell activation is not mediated by inositol lipid hydrolysis

The Ag-specific interaction between cloned allospecific human Th cells and class II MHC determinants on the surface of allogeneic B cells induces a significant fraction of resting B cells to express a B cell specific activation Ag BLAST-2 (CD23). On the other hand, cross-linking of B cell surface Ig R by Ag analogues does not lead to BLAST-2 expression. By utilizing the BLAST-2 induction assay as a positive control for efficient Th-B cell interaction, we have investigated the biochemical basis of human B cell activation mediated by Ag and Th cells. Our data demonstrate that ligands for sIg R, including F(ab')2 goat anti-human IgM and Staphylococcus aureus protein A, stimulate the metabolism of B cell membrane inositol lipids as assessed by: 1) increased [3H]inositol phosphates formation in myo-[3H]inositol-labeled B cells; 2) selective incorporation of [32P]orthophosphate into phosphatidic acid and phosphatidylinositol, but not into phosphatidylethanolamine or phosphatidylcholine; and 3) rapid increase in B cell cytoplasmic ionized Ca2+ concentration ([Ca2+]i). In contrast, direct Th-B cell interaction leads to high intensity BLAST-2 expression on the B cell surface but this response is not mediated by changes in inositol lipid metabolism or [Ca2+]i. Further, Th-B cell interaction does not affect the changes in B cell inositol lipid metabolism or [Ca2+]i triggered by sIg cross-linking. Taken together, our results suggest that Ag and Th cells induce different functional B cell responses by activating distinct second messenger systems within the B cell.     

Determination of captopril in human blood by high-performance liquid chromatography with electrochemical detection

A new method for quantitation of captopril in human blood is described. Captopril was derivatized with N-(4-dimethylaminophenyl)maleimide into the electrochemically active adduct. The derivative was separated and determined by high-performance liquid chromatography with an electrochemical detector on a reversed-phase column. The proposed method was satisfactory for determination of captopril in whole blood with respect to accuracy and precision. The detection limit of captopril thereby obtained was 10 ng/ml. The blood levels of captopril in patients orally given an officinal dose were measured by the present method.