Dietary α-linolenate suppresses endotoxin-induced platelet-activating factor production in rat kidney

In comparison with dietary high-linoleate safflower oil, high α-linolenate perilla oil decreased alkylacyl-and alkenylacyl-glycerophosphocholine (GPC) content in rat kidney by roughly 30 and 25%, respectively. The fatty acid composition was also modified by high α-linolenate oil; arachidonic acid (AA) level in alkylacyl-GPC, a platelet-activating factor (PAF) precursor, decreased by 30% along with concomitant increases in the n-3 fatty acid levels. PAF contents under resting conditions were similarly low in the two dietary groups. Fifteen minutes after endotoxin administration, PAF and lyso-PAF contents increased significantly, and the PAF content in the high α-linolenate group was 60% lower than in the high linoleate group; the lyso-PAF contents also tended to be lower. Lyso-PAF acetyltransferase and CoA-independent transacylase activities in kidney microsomes increased significantly after endotoxin administration, while PAF acetylhydrolase activity in the cytosol was relatively unchanged. The lyso-PAF acetyltransferase and PAF acetylhydrolase activities did not differ between the two dietary groups, but the CoA-independent, transacylase activity was roughly 30% lower in the high α-linolenate group. In agreement with in vitro study, our present study demonstrates that dietary high α-linolenate suppresses PAF production in rat kidney during systemic endotoxemia, and which is mainly due to the decrease in alkylacyl-GPC content, altered fatty acid compositions of the precursor lipids and lower CoA-independent transacylase activity.     

Modified DNA bearing 5(methoxycarbonylmethyl)-2'-deoxyuridine: preparation by PCR with thermophilic DNA polymerase and postsynthetic derivatization

A thymidine analogue bearing a methyl ester at the C5 position was accepted as a substrate by the thermophilic family B DNA polymerases, KOD Dash, Pwo, and Vent(exo-), to form the corresponding PCR product, but not by the thermophilic family A DNA polymerases, Taq, Tth, and T7 thermosequenase. Modified DNA containing this analogue was prepared by PCR on a large scale with KOD Dash DNA polymerase and 5(methoxycarbonylmethyl)-2'-deoxyuridine 5'-triphosphate as a substrate. The methyl ester of the modified DNA was further allowed to react with tris(2-aminoethyl)amine or histamine by an ester-amide exchange reaction to form the corresponding derivatized DNA bearing a tris(2-aminoethyl)amine or histamine moiety. Hydrolysis of the methyl ester of the modified DNA gave a functionalized DNA bearing an anionic carboxyl group. The derivatized DNA could act as a template for the PCR with KOD Dash DNA polymerase and the natural 2'-deoxythymidine 5'-triphosphate or the modified thymidine analogue as a substrate. The postsynthetic derivatization of the modified DNA may expand the variety of structurally modified DNA produced by PCR.     

Influences of miscible and immiscible oils on flow characteristics through capillary tube—part I: experimental study

A capillary tube is widely used as an expansion device for small refrigeration cycles. In a practical refrigeration cycle, some amount of refrigeration oil is discharged from a compressor and refrigerant/oil mixture flows through the capillary tube. This study investigated experimentally the influence of mixing of the refrigeration oil with the refrigerant on the flow through the capillary tube. The experiments are carried out with not only a miscible combination of refrigerant and oil but also an immiscible combination. In both cases, the mass flow rate through the capillary tube and temperature and pressure distributions along the tube are measured under several conditions of subcooled degree and oil concentration. In the case of miscible combination, the mass flow rate of refrigerant decreases with increasing the oil concentration because the viscosity of liquid phase increases by the mixing of viscous oil. Even in the case of the immiscible combination, the oil droplet is so small that it mixes homogeneously in the liquid phase in the capillary tube and the refrigerant mass flow rate decreases by the mixing of immiscible oil. There is no significant influence of the oil concentration on the underpressure, which means pressure difference between saturation pressure and flash inception pressure, in both miscible and immiscible combinations.     

Identification of a Candida glabrata homologue of the S. cerevisiae VRG4 gene,encoding the Golgi GDP-mannose transporter

Mannoproteins on the cell wall of yeast and fungi help regulate cell shape, porosity, and cell-cell interactions, including those required for attachment to host cells by fungal pathogens. The mannose-containing oligosaccharides on proteins and lipids are extended in the Golgi by glycosyltransferases that use GDP-mannose as the sugar substrate. A membrane-bound transporter that, in Saccharomyces cerevisiae, is encoded by the VRG4 gene catalyses delivery of GDP-mannose into the lumen of the Golgi. We report here the cloning of the homologous VRG4 gene from the pathogenic yeast, Candida glabrata, by functional complementation of an S. cerevisiae vrg4 mutant. The sequence of the CgVrg4 protein displays significant homology to GDP-mannose transporters from other yeast, fungi, protozoa, and plants. CgVRG4 fully complements the glycosylation defect and other cell wall associated vrg4 mutant phenotypes. Like ScVRG4, CgVRG4 is essential for the viability of C. glabrata. These results suggest that, as in S. cerevisiae, CgVrg4p accounts for all of the GDP-mannose transport activity in the Golgi lumen.     

用于PEMFC的Pt/C阳极催化剂制备与性能研究

为了提高PEMFC的阳极催化剂活性,降低Pt载量,分别采用甲醛、甲酸钠、连二亚硫酸钠、水合肼4种还原剂通过化学还原沉积法制备Pt/C催化剂;向溶液中加入某种羧酸盐(RCOOM)作为吸附剂,制备Pt/C催化剂;利用粉末微电极的循环伏安研究和恒电位极化研究考核了上述催化剂对H_2阳极氧化的催化活性的影响;通过XRD和TEM技术对催化剂的结构及微观形貌进行了分析。结果表明,甲醛作为还原剂得到的铂催化剂在碳载体上分布均匀,粒径较小,催化性能最好;加入适量吸附剂则使Pt颗粒的平均粒径减小到3.4nm,催化剂性能有明显改善。     

Reduced common-mode modulation strategies for cascaded multilevel inverters

This paper presents modulation strategies for cascaded multilevel inverters that substantially eliminate common-mode voltage on the output phases. The paper begins by developing generic multilevel inverter reference waveforms that use only "allowed" space vectors to achieve reduced common-mode voltage. A graphical technique is then proposed that allows various carrier disposition modulation strategies for a diode-clamped inverter to be converted to equivalent modulation of a cascaded inverter for any fundamental reference waveform. This graphical technique is confirmed for both alternative phase opposition disposition and phase disposition equivalent modulation of a cascaded inverter, and is then used to create reduced common-mode modulation strategies for cascaded inverters from their equivalent counterparts for diode-clamped inverters under both continuous and discontinuous switching conditions. The strategies have been confirmed by both simulation and experimental results obtained using a cascaded five-level inverter.     

Formation of a thiamine disulfide complex with fatty acid: Mechanism of formation of the complex

The formation of complexes between thiamine disulfide (TDS) orO-acetyl thiamine disulfide (O-acetyl TDS) and fatty acid or fatty acid methyl ester in methanol has been studied by fluorescence quenching and¹³C NMR relaxation (T₁) measurements. The association constants (K-values) of TDS andO-acetyl TDS with fatty acids (from 11∶0 to 18∶0, and 18∶1, 18∶2, 18∶3 and 20∶4) and fatty acid methyl esters have been determined. These values do not depend on either the number of carbon atoms or the degree of unsaturation of the fatty acid. The K-values of TDS andO-acetyl TDS with fatty acid were 7.8 M⁻¹ and 5.1 M⁻¹, respectively. The K-values of TDS andO-acetyl TDS with fatty acid methyl ester were very small. These results show that the-OH moiety in TDS and the-COOH moiety in the fatty acid are necessary for formation of the complex     

Structural analysis of unknown dyes detected in hajikami (ginger pickled in vinegar)

Hajikami (ginger pickled in vinegar) is often used as a relish for grilled fish, and it often contains coloring agents. We detected Rose Bengal (R105) and two unknown dyes in some Hajikami by thin layer chromatography. In this study, we tried to characterize these unknown dyes by HPLC with photodiode array detection (PDA-HPLC), liquid chromatography/mass spectrometry (LC/MS) and nuclear magnetic resonance (NMR). PDA-HPLC analysis showed that the spectra of the unknown dyes resembled that of R105, suggesting the molecular structures of these two dyes are similar to that of R105. Furthermore, LC/MS analysis suggested that the these dyes are R105 in which one or two iodines are replaced by hydrogen. Finally, the two dyes were determined by 1H-NMR and 13C-NMR to be 4,5,6,7-tetrachloro-3',6'-dihydroxy-2',7'-diiodo spiro[isobenzofuran- 1 (3H),9'-[9H]xanthen]-3-one disodium salt and 4,5,6,7-tetrachloro-3',6'-dihydroxy-2',7'-diiodo spiro[isobenzofuran-1(3H),9'[9H]xanthen]-3-one disodium salt.