Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001

Spatial and seasonal egg production rates (E_r) and egg hatchingsuccess in the copepods Calanus finmarchicus and Calanus helgolandicuswere measured in the North Sea from March to September. Foodavailability was monitored by chlorophyll and protist concentrationsand three size fractions of seston fatty acids. Seasonal andspatial distribution and production differed between the species.Calanus finmarchicus was found only offshore of the 50-m isobath,with decreasing E_r (37–28 eggs female^–1 day^–1)from March to July. Calanus helgolandicus had two abundancepeaks, in spring and autumn, with a low in May during whichtime the highest E_r were observed (38 eggs female^–1 day^–1).At other times, E_r in C. helgolandicus remained lower than inC. finmarchicus (     

Luminol assay for microdetermination of superoxide dismutase activity: its application to human fetal blood

A microtechnique for determining the superoxide dismutase activity in erythrocytes is described. This technique involves the inhibition of luminol-enhanced chemiluminescence of superoxide anion generated by xanthine-xanthine oxidase. Measurements required a steady-state chemiluminescence whether superoxide dismutase was present or absent; the level of luminescence was correlated to enzyme activity. Superoxide dismutase activity measured by this technique was 836 +/- 112 micrograms/g of hemoglobin for whole blood and 834 +/- 109 micrograms/g of hemoglobin for erythrocytes. When the reference technique was applied to larger amounts of blood, the results were 862 +/- 58 and 858 +/- 116 micrograms/g of hemoglobin for whole blood and washed erythrocytes, respectively. The enzymatic activity of superoxide dismutase from fetal blood (obtained by venipuncture in utero and of 19-26 weeks gestational age) was similar to that of adult blood, when measured by the new technique.     

Role of cytochrome b-559 in arachidonic acid activation of resting human neutrophils

Whether or not cytochrome b-559 is a necessary component of NADPH oxidase activity in neutrophils is still controversial. In highly purified plasma membranes isolated from resting neutrophils and lacking cytochrome b, addition of arachidonic acid induced an NADPH oxidase activity. This activity was similar to that of plasma membranes isolated from phorbol myristate acetate (PMA)-stimulated cells which possessed cytochrome b. Addition of arachidonic acid to the latter plasma membranes did not alter the oxidase activity. It can be concluded that plasma membranes isolated from resting neutrophils have, in the presence of arachidonic acid, an NADPH oxidase activity similar to that of PMA-stimulated cells, except that it is independent of cytochrome b-559.     

The induction of valine dehydrogenase activity from Streptomyces by L-valine is not repressed by ammonium

Summary Activity of valine dehydrogenases (VDH) from Streptomyces aureofaciens and S. fradiae is strongly induced by L-valine even in the presence of 25mM NH₄ ⁺. When added into 16 h-old cultures growing with 100mM NH₄ ⁺, L-valine induced the synthesis of VDH. The results indicate that Streptomyces can utilize L-valine in the presence of NH₄ ⁺, and the induction of VDH activity by L-valine is not repressed by NH₄ ⁺.     

Pharmacophore requirements in new series of pyridazinyl alkanoic acids, N-[(pyridazin-2-yl) alkyl] succinyl and glutaryl amides, inhibitors of thromboxane A2 biosynthesis

New series of 5-benzyl-6-methyl-4-oxo pyridazin-2-yl alkanoic acids, N-[(pyridazin-2-yl)alkyl] succinyl and glutaryl amides have been synthesized and evaluated in vitro as TXA₂ biosynthesis inhibitors. The experiments were carried out using arachidonic acid (32.8 μM) as a substrate and horse platelet microsomes as sources of TXA₂ synthase. The presence of TXB₂, a stable metabolite of TXA₂, was determined by RIA. The potency of active compounds (1.10⁻⁴ < IC 50 < 1.10⁻⁶ M) greatly depends on the length of the chain at the N-2 position on the pyridazine ring. Furthermore, enzyme inhibition in vitro is increased with the presence of a halogen atom on the aromatic moiety of the benzyl group at C-5. Compound 4f having a pentanoic side chain and a 4-fluoro benzyl moiety was the most active derivative with an IC₅₀ value of 6.69 × 10⁻⁶ M. Molecular modelling studies were done on all the synthesized pyridazinones and on prostaglandin H₂ (PGH₂) suggesting spatial features and volumes of TXA₂ synthase pharmacophore mode in these series of derivatives.     

Regulation of the formation of proteinases inBacillus megaterium

Absrract The exocellular proteinases from the asporogenic and sporogenic strain ofBacillus megaterium KM were purified and characterized. They are both neutral metalloenzymes, having an optimum pH of 7.2. The bivalent metal cations, particularly calcium or magnesium, are essential for their activity. The curve of the relationship between the reaction velocity and the concentrations of Ca²⁺ resembles the Michaelis curve for substrate concentration. The enzymes also require metal cations for their stability. Both proteinases are inactivated byo-phenanthroline (lmm) and are resistant against diisopropyl fluorophosphate (lmm) and sodium-p-chloromercuribenzoate (lmm) treatment. In spite of the difference in biochemical regulation of their synthesis, these exocellular proteinases seem to be similar. The terms, megaterioproteinase A and megaterioproteinase S have been proposed for these enzymes.     

Pelliolatifolias A-D,Four Undescribed Compounds from Pellionia latifolia Boerl. and Their Nitric Oxide Production Inhibitory Activity

Four undescribed compounds ( 1 – 4 ) named pelliolatifolias A−D together with seven known compounds trans-clovamide ( 5 ), N-trans-caffeoyl-4-hydroxyphenylalanine methyl ester ( 6 ), N-trans-caffeoyl-3,4-dihydroxyphenylalanine methyl ester ( 7 ), luteolin 4’-O-β-D-glucopyrannoside ( 8 ), cis-syringin ( 9 ), trans-syringin ( 10 ), and citroside A ( 11 ) have been isolated from the methanol extract of the Pellionia latifolia leaves. Their chemical structures were elucidated based on extensive analyses of HR-ESI-MS, 1D and 2D NMR, and CD spectra. Compounds 1 – 7 , 9 and 10 showed moderate inhibition of NO production in LPS-activated RAW264.7 cells with their IC₅₀ values ranging from 39.27 to 75.42 μM, compared to that of the positive control compound, dexamethasone, IC₅₀ value of 14.20 μM.     

Amenyunnaosides A–C,Three New Neolignans Isolated from Amentotaxus yunnanensis and Their Anti-inflammatory Activities

Phytochemical study on the leaves of Amentotaxus yunnanensis led to the isolation of seventeen phenolic compounds including sixteen neolignans and lignans, and one flavone glycoside. Three among the isolates were previously unreported neolignans and named as amenyunnaosides A–C, respectively. Their structures were elucidated by extensive analyses of HR-ESI-MS, 1D and 2D NMR, and ECD spectra. The isolated neolignans potentially inhibited NO production in LPS-activated RAW264.7 cells with their IC₅₀ values ranging from 11.05 to 44.07 μM, compared to that of the positive control compound, dexamethasone, IC₅₀ value of 16.93 μM. Additionally, amenyunnaoside A dose-dependently reduced production of IL-6 and COX-2 but did not effect to that of TNF-α at concentrations of 0.8, 4, and 20 μM.     

Discovery of Four New Compounds from Macropanax membranifolius and Their Cytotoxic Activity

A phytochemical investigation of the methanolic extract of the Macropanax membranifolius C.B. Shang leaves led to the isolation of three new flavans, (2R,3R)-4′-O-methylcatechin 5-O-β-D-glucopyranoside ( 1 ), (2S,3S)-4′-O-methylcatechin 5-O-β-D-glucopyranoside ( 2 ), (2S,3R)-4′-O-methylcatechin 5-O-β-D-glucopyranoside ( 3 ), one new triterpene glycoside 3-O-β-D-xylopyranosyl-(1→6)-[β-D-xylopyranosyl-(1→2)]-β-D-glucopyranosyl-oleanolic acid 28-O-β-D-glucopyranoside ( 4 ), together with nine known compounds ( 5 - 13 ). Their chemical structures were elucidated based on HR-ESI-MS, NMR spectroscopic data. The absolute configurations of compounds 1 – 3 were established by electronic circular dichroism (ECD) spectra. At concentration of 20 μM, compounds 1 – 13 showed the percentages of dead cell in the range of 2.14 % to 33.61 % against KB, HepG2, HL60, P388, HT29, and MCF7 cancerous cell lines by SRB assay.     

The influence of host and bacterial genotype on the development of disseminated disease with Mycobacterium tuberculosis

The factors that govern the development of tuberculosis disease are incompletely understood. We hypothesized that some strains of Mycobacterium tuberculosis (M. tuberculosis) are more capable of causing disseminated disease than others and may be associated with polymorphisms in host genes responsible for the innate immune response to infection. We compared the host and bacterial genotype in 187 Vietnamese adults with tuberculous meningitis (TBM) and 237 Vietnamese adults with uncomplicated pulmonary tuberculosis. The host genotype of tuberculosis cases was also compared with the genotype of 392 cord blood controls from the same population. Isolates of M. tuberculosis were genotyped by large sequence polymorphisms. The hosts were defined by polymorphisms in genes encoding Toll-interleukin 1 receptor domain containing adaptor protein (TIRAP) and Toll-like receptor-2 (TLR-2). We found a significant protective association between the Euro-American lineage of M. tuberculosis and pulmonary rather than meningeal tuberculosis (Odds ratio (OR) for causing TBM 0.395, 95% confidence intervals (C.I.) 0.193-0.806, P = 0.009), suggesting these strains are less capable of extra-pulmonary dissemination than others in the study population. We also found that individuals with the C allele of TLR-2 T597C allele were more likely to have tuberculosis caused by the East-Asian/Beijing genotype (OR = 1.57 [95% C.I. 1.15-2.15]) than other individuals. The study provides evidence that M. tuberculosis genotype influences clinical disease phenotype and demonstrates, for the first time, a significant interaction between host and bacterial genotypes and the development of tuberculosis.