Synthesis and antiplatelet, antiinflammatory, and antiallergic activities of 2-substituted 3-chloro-1,4-naphthoquinone derivatives

A series of 2-substituted 3-chloro-1,4-naphthoquinones was synthesized, and the antiplatelet, antiinflammatory, and antiallergic activities of these compounds were evaluated. The structure-activity relationships in this series were also examined. Most of the 2-alkyl/arylcarboxamido derivatives of 3-chloro-1,4-naphthoquinone showed potent activities with similar trends in each of the activities evaluated.     

Marine finfish hatchery technology in the USA – status and future

In 1993, about 52% of the 433 698 tons of thetotal US aquaculture production came from theproduction of freshwater catfish. Excludingsalmonid culture, the percentage of marine finfishculture in total aquaculture production in the UShas been negligible. Commercial scale production ofmarine finfish in hatcheries is very limited in theUS.Studies on eggs and larvae of marine finfishspecies in the US have stemmed from theconsideration of fisheries management rather thanaquaculture. Most of the marine finfish larvaeproduced in the laboratory has been for the purposeof providing materials for other academic relatedstudies. Results of these studies can be applied inthe development of marine finfish hatcherytechnology. Hatchery technology for several marinefinfish species has been developed for stockenhancement, technology transfer and aquaculture. This paper reviews the current hatchery technologyof striped mullet (Mugil cephalus), dolphinfish (Coryphaena hippurus), red drum (Sciaenops ocellatus), and other potentialaquaculture species.     

Cloning and characterization of two catA genes in Acinetobacter lwoffii K24.

Two novel type I catechol 1,2-dioxygenases inducible on aniline media were isolated from Acinetobacter lwoffii K24. Although the two purified enzymes, CD I1 and CD I2, had similar intradiol cleavage activities, they showed different substrate specificities for catechol analogs, physicochemical properties, and amino acid sequences. Two catA genes, catA1 and catA2, encoding by CD I1 and CD I2, respectively, were isolated from the A. lwoffii K24 genomic library by using colony hybridization and PCR. Two DNA fragments containing the catA1 and catA2 genes were located on separate regions of the chromosome. They contained open reading frames encoding 33.4- and 30.4-kDa proteins. The amino acid sequences of the two proteins matched well with previously determined sequences. Interestingly, further analysis of the two DNA fragments revealed the locations of the catB and catC genes as well. Moreover, the DNA fragment containing catA1 had a cluster of genes in the order catB1-catC1-catA1 while the catB2-catA2-catC2 arrangement was found in the catA2 DNA fragment. These results may provide an explanation of the different substrate specificities and physicochemical properties of CD I1 and CD I2.     

Purification and characterization of 2,6-dichloro-p-hydroquinone chlorohydrolase from Flavobacterium sp. strain ATCC 39723.

The biochemistry of pentachlorophenol (PCP) degradation by Flavobacterium sp. strain ATCC 39723 has been studied, and two enzymes responsible for the conversion of PCP to 2,6-dichloro-p-hydroquinone (2,6-DiCH) have previously been purified and characterized. In this study, enzymatic activities consuming 2,6-DiCH were identified from the cell extracts of strain ATCC 39723. The enzyme was purified to apparent homogeneity by a purification scheme consisting of seven steps. Gel filtration chromatography showed a native molecular weight of about 40,000, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single protein of 42,500 Da. The purified enzyme converted 2,6-DiCH to 6-chlorohydroxyquinol (6-chloro-1,2,4-trihydroxybenzene), which was easily oxidized by molecular oxygen and hard to detect. The end product, 6-chlorohydroxyquinol, was detected only in the presence of a reductase and NADH in the reaction mixture. The enzyme dechlorinated 2,6-DiCH but not 2,5-DiCH. The enzyme required Fe2+ for activity and was severely inhibited by metal chelating agents. The optimal conditions for activity were pH 7.0 and 40 degrees C. The Kcat for 2,6-DiCH was 35 microM, and the kcat was 0.011 s-1.     

Novel β-Secretase Cleavage of β-Amyloid Precursor Protein in the Endoplasmic Reticulum/Intermediate Compartment of NT2N Cells

Previous studies have demonstrated that NT2N neurons derived from a human embryonal carcinoma cell line (NT2) constitutively process the endogenous wild-type β-amyloid precursor protein (APP) to amyloid β peptide in an intracellular compartment. These studies indicate that other proteolytic fragments generated by intracellular processing must also be present in these cells. Here we show that the NH₂-terminal fragment of APP generated by β-secretase cleavage (APPβ) is indeed produced from the endogenous full length APP (APP_FL). Pulse–chase studies demonstrated a precursor–product relationship between APP_FL and APPβ as well as intracellular and secreted APPβ fragments. In addition, trypsin digestion of intact NT2N cells at 4°C did not abolish APPβ recovered from the cell lysates. Furthermore, the production of intracellular APPβ from wild-type APP appears to be a unique characteristic of postmitotic neurons, since intracellular APPβ was not detected in several non-neuronal cell lines. Significantly, production of APPβ occurred even when APP was retained in the ER/ intermediate compartment by inhibition with brefeldin A, incubation at 15°C, or by expression of exogenous APP bearing the dilysine ER retrieval motif.     

Evidence for Multiple, Local Functions of Ciliary Neurotrophic Factor (CNTF) in Retinal Development: Expression of CNTF and Its Receptor and In Vitro Effects on Target Cells

Abstract: There is increasing, although largely indirect, evidence that neurotrophic factors not only function as target-derived survival factors for projection neurons, but also act locally to regulate developmental processes. We studied the expression of ciliary neurotrophic factor (CNTF) and the CNTF-specific ligand-binding α-subunit of the CNTF receptor complex (CNTFRα) in the rat retina, a well-defined CNS model system, and CNTF effects on cultured retinal neurons. Both CNTF and CNTFRα (mRNA and protein) are expressed during phases of retinal neurogenesis and differentiation. Retina-specific Müller glia are immunocytochemically identified as the site of CNTF production and CNTFRα-expressing, distinct neuronal cell types as potential CNTF targets. Biological effects on corresponding neurons in culture further support the conclusion that locally supplied CNTF plays a regulatory role in the development of various retinal cell types including ganglion cells and interneurons.     

Utilization of chemokine receptors, orphan receptors, and herpesvirus-encoded receptors by diverse human and simian immunodeficiency viruses.

Human immunodeficiency virus type 1 (HIV-1) requires both CD4 and a coreceptor to infect cells. Macrophage-tropic (M-tropic) HIV-1 strains utilize the chemokine receptor CCR5 in conjunction with CD4 to infect cells, while T-cell-tropic (T-tropic) strains generally utilize CXCR4 as a coreceptor. Some viruses can use both CCR5 and CXCR4 for virus entry (i.e., are dual-tropic), while other chemokine receptors can be used by a subset of virus strains. Due to the genetic diversity of HIV-1, HIV-2, and simian immunodeficiency virus (SIV) and the potential for chemokine receptors other than CCR5 or CXCR4 to influence viral pathogenesis, we tested a panel of 28 HIV-1, HIV-2, and SIV envelope (Env) proteins for the ability to utilize chemokine receptors, orphan receptors, and herpesvirus-encoded chemokine receptor homologs by membrane fusion and virus infection assays. While all Env proteins used either CCR5 or CXCR4 or both, several also used CCR3. Use of CCR3 was strongly dependent on its surface expression levels, with a larger number of viral Env proteins being able to utilize this coreceptor at the higher levels of surface expression. ChemR1, an orphan receptor recently shown to bind the CC chemokine I309 (and therefore renamed CCR8), was expressed in monocyte and lymphocyte cell populations and functioned as a coreceptor for diverse HIV-1, HIV-2, and SIV Env proteins. Use of ChemR1/CCR8 by SIV strains was dependent in part on V3 loop sequences. The orphan receptor V28 supported Env-mediated cell-cell fusion by four T- or dual-tropic HIV-1 and HIV-2 strains. Three additional orphan receptors failed to function for any of the 28 Env proteins tested. Likewise, five of six seven-transmembrane-domain receptors encoded by herpesviruses did not support Env-mediated membrane fusion. However, the chemokine receptor US28, encoded by cytomegalovirus, did support inefficient infection by two HIV-1 strains. These findings indicate that additional chemokine receptors can function as HIV and SIV coreceptors and that surface expression levels can strongly influence coreceptor use.     

Differential recruitment of B and T cells in coxsackievirus B4-induced pancreatitis is influenced by a capsid protein.

Two genetically similar variants of coxsackievirus B4, CB4-P and CB4-V, cause distinct disease syndromes in mice. A multidisciplinary approach was used to examine the events occurring in situ. The CB4-P variant induced acute pancreatitis, followed by repair of the exocrine tissues, while the CB4-V variant induced chronic pancreatitis, characterized by extensive destruction of the exocrine tissues. Since CB4-V replicated more efficiently than CB4-P in vivo, the more extensive tissue injury associated with CB4-V infection could be explained as the result of a higher level of viral replication. However, the fact that CB4-V replicated more efficiently in a mouse strain that survives infection than in a strain that succumbs to infection suggests that immune-mediated mechanisms as well as viral cytolysis may contribute to pancreatic tissue injury. To address the role of the immune system in virus-induced pancreatitis, the cell types within the inflammatory infiltrate were analyzed by flow cytometry. B cells (34 to 75%) were the most abundant, followed by T cells (10 to 30%), natural killer cells (4 to 8%), and macrophages (0 to 6%). Recruitment (and perhaps proliferation) of B and T cells to the pancreatic tissues was influenced by viral strain. Differential recruitment of T and B cells may reflect altered antigenic sites between CB4-P and CB4-V. The viral sequence that affected T- and B-cell recruitment was identified as a threonine residue at position 129 of the VP1 capsid protein.     

KINETICS OF CELL DEATH IN THE CYANOBACTERIUM ANABAENA FLOS-AQUAE AND THE PRODUCTION OF DISSOLVED ORGANIC CARBON1

Kinetics of cell death and the production of dissolved organic carbon (DOC) were investigated in Anabaena flos-aquae (Lyngb.) Bréb grown on three different N sources (N₂nitrate, and ammonium) in a phosphorus (P)-limited chemostat. The fraction of live cells in the total population increased as growth rate increased with decreasing P limitation. Cell death was less in nitrate and ammonium media than in N₂. The specific death rate (γ), when calculated as the slope ofv^?1_x vs. D^?1, where v_xand D are live cell fraction (or cell viability) and dilution rate, respectively, was 0. 0082 day^?1 in N₂and 0.0042 day^?1 in nitrate. The slope of the plot in ammonium culture was not significant; however, the value of the live cell fraction was within the range for the NO^?₃culture. The fraction of live vegetative cells in N₂ culture was constant at all growth rates and the increase in the overall live cell fraction with growth rate was due entirely to an increase in live heterocysts. Live heterocysts comprised 3.5% of the total cells at a growth rate of 0.25 day^?1 and increased to 6.3% at 0.75 day^?1 with the ratio of live heterocysts to live vegetative cells linearly increasing with growth rate. The fraction of live vegetative cells was invariant in nitrate cultures us in N₂cultures. The live heterocysts fraction also increased with growth rate in nitrate cultures, along with the live heterocysts : live vegetative cells ratio, but the level was lower than in N₂cultures. DOC released from dead cells increased inversely with growth rate in N₂from 36.4% of the total DOC at a growth rate of 0.75 day^?1 to 54.15% at 0.25 day^?1. The contribution of cell death to the total DOC production in nitrate and ammonium media was significantly less than that under N₂DOC from dead cells consisted mainly of high-molecular-weight compounds, whereas DOC excreted from live cells was largely of low molecular weight.