Lipoprotein lipase inhibits hepatitis C virus (HCV) infection by blocking virus cell entry

A distinctive feature of HCV is that its life cycle depends on lipoprotein metabolism. Viral morphogenesis and secretion follow the very low-density lipoprotein (VLDL) biogenesis pathway and, consequently, infectious HCV in the serum is associated with triglyceride-rich lipoproteins (TRL). Lipoprotein lipase (LPL) hydrolyzes TRL within chylomicrons and VLDL but, independently of its catalytic activity, it has a bridging activity, mediating the hepatic uptake of chylomicrons and VLDL remnants. We previously showed that exogenously added LPL increases HCV binding to hepatoma cells by acting as a bridge between virus-associated lipoproteins and cell surface heparan sulfate, while simultaneously decreasing infection levels. We show here that LPL efficiently inhibits cell infection with two HCV strains produced in hepatoma cells or in primary human hepatocytes transplanted into uPA-SCID mice with fully functional human ApoB-lipoprotein profiles. Viruses produced in vitro or in vivo were separated on iodixanol gradients into low and higher density populations, and the infection of Huh 7.5 cells by both virus populations was inhibited by LPL. The effect of LPL depended on its enzymatic activity. However, the lipase inhibitor tetrahydrolipstatin restored only a minor part of HCV infectivity, suggesting an important role of the LPL bridging function in the inhibition of infection. We followed HCV cell entry by immunoelectron microscopy with anti-envelope and anti-core antibodies. These analyses demonstrated the internalization of virus particles into hepatoma cells and their presence in intracellular vesicles and associated with lipid droplets. In the presence of LPL, HCV was retained at the cell surface. We conclude that LPL efficiently inhibits HCV infection by acting on TRL associated with HCV particles through mechanisms involving its lipolytic function, but mostly its bridging function. These mechanisms lead to immobilization of the virus at the cell surface. HCV-associated lipoproteins may therefore be a promising target for the development of new therapeutic approaches.     

Patronage and 'community': the role of a Tamil 'village' festival in the integration of a town

Focusing on the festival of 'village' goddesses in two small towns in Tamilnadu, South India, the article investigates how the urban organization of temples and festivals reflects characteristics of the organization of similar festivals in villages, whilst at the same time the 'acts of patronage' of wealthy local industrialists increasingly shape the nature of the 'community' generated at festival and other times. Building on idioms of village community and pre-colonial kingship models, industrialists are central to the formation of a sense of community which transcends the borders of caste and class. It is argued that the formation of community boundaries cannot be understood outside the context of the wider social and economic relationships and, in this case, the labour relations which lie at the heart of South Indian textile industries.     

Behavioral testing of antidepressant compounds: an analysis of crossover design for correlated binary data

The differential reinforcement of low-rate 72 seconds schedule (DRL-72) is a standard behavioral test procedure for screening potential antidepressant compounds. The protocol for the DRL-72 experiment, proposed by Evenden et al. (1993), consists of using a crossover design for the experiment and one-way ANOVA for the statistical analysis. In this paper we discuss the choice of several crossover designs for the DRL-72 experiment and propose to estimate the treatment effects using either generalized linear mixed models (GLMM) or generalized estimating equation (GEE) models for clustered binary data.     

Obstructive sleep apnea: Plasma endothelin-1 precursor but not endothelin-1 levels are elevated and decline with nasal continuous positive airway pressure

Assessment of plasma endothelin-1 (ET-1) reveals conflicting results in cerebral and noncerebral conditions. Obstructive sleep apnea (OSA) syndrome has been used as a definite challenge for the investigation of endothelin measurements. Despite marked sleep-related breathing disturbances in untreated patients peripherally measurable ET-1 concentrations remained within the normal range and did not change after an appropriate therapy with continuous positive airway pressure (CPAP). In contrast, its precursor, big ET-1, was considerably elevated in untreated patients and dropped to normal values after long-term CPAP depending on compliance. Relatively stable big ET-1 elevations in untreated patients, during sleep and wakefulness, suggest that a general endothelial alteration beyond that explained by a direct impact of nocturnal breathing disturbances on the vascular system occurs. CPAP-therapy effectively lowered plasma big ET-1 in compliant patients and thus possibly their related risk for vascular diseases. Big ET-1 has been demonstrated to be a more appropriate marker of endothelial alteration than ET-1 because of its longer half-life. Simultaneous measurements are to be recommended.     

Insulin modulates hippocampal activity-dependent synaptic plasticity in a N-methyl-d-aspartate receptor and phosphatidyl-inositol-3-kinase-dependent manner

Insulin and its receptor are both present in the central nervous system and are implicated in neuronal survival and hippocampal synaptic plasticity. Here we show that insulin activates phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB), and results in an induction of long-term depression (LTD) in hippocampal CA1 neurones. Evaluation of the frequency-response curve of synaptic plasticity revealed that insulin induced LTD at 0.033 Hz and LTP at 10 Hz, whereas in the absence of insulin, 1 Hz induced LTD and 100 Hz induced LTP. LTD induction in the presence of insulin required low frequency synaptic stimulation (0.033 Hz) and blockade of GABAergic transmission. The LTD or LTP induced in the presence of insulin was N-methyl-d-aspartate (NMDA) receptor specific as it could be inhibited by alpha-amino-5-phosphonopentanoic acid (APV), a specific NMDA receptor antagonist. LTD induction was also facilitated by lowering the extracellular Mg(2+) concentration, indicating an involvement of NMDA receptors. Inhibition of PI3K signalling or discontinuing synaptic stimulation also prevented this LTD. These results show that insulin modulates activity-dependent synaptic plasticity, which requires activation of NMDA receptors and the PI3K pathway. The results obtained provide a mechanistic link between insulin and synaptic plasticity, and explain how insulin functions as a neuromodulator.     

Gene expression programs during Brassica oleracea seed maturation, osmopriming, and germination are indicators of progression of the germination process and the stress tolerance level

During seed maturation and germination, major changes in physiological status, gene expression, and metabolic events take place. Using chlorophyll sorting, osmopriming, and different drying regimes, Brassica oleracea seed lots of different maturity, stress tolerance, and germination behavior were created. Through careful physiological analysis of these seed lots combined with gene expression analysis using a dedicated cDNA microarray, gene expression could be correlated to physiological processes that occurred within the seeds. In addition, gene expression was studied during early stages of seed germination, prior to radicle emergence, since very little detailed information of gene expression during this process is available. During seed maturation expression of many known seed maturation genes, such as late-embryogenesis abundant or storage-compound genes, was high. Notably, a small but distinct subgroup of the maturation genes was found to correlate to seed stress tolerance in osmoprimed and dried seeds. Expression of these genes rapidly declined during priming and/or germination in water. The majority of the genes on the microarray were up-regulated during osmopriming and during germination on water, confirming the hypothesis that during osmopriming, germination-related processes are initiated. Finally, a large group of genes was up-regulated during germination on water, but not during osmopriming. These represent genes that are specific to germination in water. Germination-related gene expression was found to be partially reversible by physiological treatments such as slow drying of osmoprimed seeds. This correlated to the ability of seeds to withstand stress.     

Metabolite Profiling Reveals a Role for Atypical Cinnamyl Alcohol Dehydrogenase CAD1 in the Synthesis of Coniferyl Alcohol in Tobacco Xylem

In angiosperms, lignin is built from two main monomers, coniferyl and sinapyl alcohol, which are incorporated respectively as G and S units in the polymer. The last step of their synthesis has so far been considered to be performed by a family of dimeric cinnamyl alcohol dehydrogenases (CAD2). However, previous studies on Eucalyptus gunnii xylem showed the presence of an additional, structurally unrelated, monomeric CAD form named CAD1. This form reduces coniferaldehyde to coniferyl alcohol, but is inactive on sinapaldehyde. In this paper, we report the functional characterization of CAD1 in tobacco (Nicotiana tabacum L.). Transgenic tobacco plants with reduced CAD1 expression were obtained through an RNAi strategy. These plants displayed normal growth and development, and detailed biochemical studies were needed to reveal a role for CAD1. Lignin analyses showed that CAD1 down-regulation does not affect Klason lignin content, and has a moderate impact on G unit content of the non-condensed lignin fraction. However, comparative metabolic profiling of the methanol-soluble phenolic fraction from basal xylem revealed significant differences between CAD1 down-regulated and wild-type plants. Eight compounds were less abundant in CAD1 down-regulated lines, five of which were identified as dimers or trimers of monolignols, each containing at least one moiety derived from coniferyl alcohol. In addition, 3-trans-caffeoyl quinic acid accumulated in the transgenic plants. Together, our results support a significant contribution of CAD1 to the synthesis of coniferyl alcohol in planta, along with the previously characterized CAD2 enzymes. Sequences of NtCAD1-1 and NtCAD1-7 were deposited in GenBank under accession numbers AY911854 and AY911855, respectively.