Helminthic therapy: improving mucosal barrier function

The epidemiology of autoimmune diseases and helminth infections led to suggestions that helminths could improve inflammatory conditions, which was then tested using animal models. This has translated to clinical investigations aimed at the safe and controlled reintroduction of helminthic exposure to patients suffering from autoimmune diseases (so-called 'helminthic therapy') in an effort to mitigate the inflammatory response. In this review, we summarize the results of recent clinical trials of helminthic therapy, with particular attention to mechanisms of action. Whereas previous reviews have emphasized immune regulatory mechanisms activated by helminths, we propose that enhancement of mucosal barrier function may have an equally important role in improving conditions of inflammatory bowel diseases.     

Determinants of Compliance Behaviours among Patients Undergoing Hemodialysis in Malaysia

Background

Patients with end stage renal disease often fail to follow prescribed dietary and fluid regimen, leading to undesirable outcomes. This study aimed to examine and identify factors influencing dietary, fluid, medication and dialysis compliance behaviours in patients undergoing hemodialysis.

Methods

This was a cross-sectional study which employed purposive sampling design. A total of 188 respondents were recruited from 14 dialysis centres in Malaysia between 2008–2011. Self-reported compliance behaviours and biochemical measurements were used as evaluation tools.

Results

Compliance rates of dietary, fluid, medication and dialysis were 27.7%, 24.5%, 66.5% and 91.0%, respectively. Younger, male, working patients and those with longer duration on hemodialysis were found more likely to be non-compliant. Lacks of adequate knowledge, inadequate self-efficacy skills, forgetfulness and financial constraints were the major perceived barriers towards better compliance to fluid, dietary, medication and dialysis, respectively.

Conclusions

Healthcare professionals should recognise the factors hindering compliance from the patients'' perspective while assisting them with appropriate skills in making necessary changes possible.     

Id-1 induces proteasome-dependent degradation of the HBX protein

Id-1 is a member of the HLH protein family that regulates a wide range of cellular processes such as cell proliferation, apoptosis, senescence and overexpression of Id-1 was recently suggested to play roles in the development and progression of different cancers. Previously, Id-1 was shown to physically interact with the viral protein E1A. Meanwhile, Id-1 expression was found to be regulated by several of the virus-encoded proteins, suggesting that Id-1 may be a common cellular target of the viral proteins. Here, we report that Id-1 interacts with the Hepatitis-B virus (HBV)-encoded protein HBX and regulates its stability in hepatocellular carcinoma (HCC) cells. We found that in HCC cells, ectopic Id-1 expression significantly decreased the half-life of the HBX protein, indicating that HBX is destabilized by Id-1. Meanwhile, the Id-1-induced HBX degradation was found to be inhibited by treatment with proteasome inhibitor, suggesting that this process is mediated through the proteasome pathway. Interestingly, while Id-1 did not induce HBX-ubiquitination, we found that removal of all the lysine residues of the HBX protein protects it from the effect of Id-1, indicating that ubiquitination is still required for the Id-1-mediated HBX degradation. Meanwhile, we found that Id-1 binds to the proteasome subunit C8 and facilitates its interaction with the HBX protein and disruption of this interaction completely abolishes the negative effect of Id-1 on HBX protein stability. Taken together, our results demonstrated a novel function of Id-1 in regulating HBX protein stability through interaction with the proteasome.     

Slow Mitochondrial COI Sequence Evolution at the Base of the Metazoan Tree and Its Implications for DNA Barcoding

The evolution rates of mtDNA in early metazoans hold important implications for DNA barcoding. Here, we present a comprehensive analysis of intra- and interspecific COI variabilities in Porifera and Cnidaria (separately as Anthozoa, Hydrozoa, and Scyphozoa) using a data set of 619 sequences from 224 species. We found variation within and between species to be much lower in Porifera and Anthozoa compared to Medusozoa (Hydrozoa and Scyphozoa), which has divergences similar to typical metazoans. Given that recent evidence has shown that fungi also exhibit limited COI divergence, slow-evolving mtDNA is likely to be plesiomorphic for the Metazoa. Higher rates of evolution could have originated independently in Medusozoa and Bilateria or been acquired in the Cnidaria + Bilateria clade and lost in the Anthozoa. Low identification success and substantial overlap between intra- and interspecific COI distances render the Anthozoa unsuitable for DNA barcoding. Caution is also advised for Porifera and Hydrozoa because of relatively low identification success rates as even threshold divergence that maximizes the “barcoding gap” does not improve identification success. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Interaction of caveolin-1, nitric oxide, and nitric oxide synthases in hypoxic human SK-N-MC neuroblastoma cells

Neuroblastoma cells are capable of hypoxic adaptation, but the mechanisms involved are not fully understood. We hypothesized that caveolin-1 (cav-1), a plasma membrane signal molecule, might play a role in protecting neuroblastoma cells from oxidative injury by modulating nitric oxide (NO) production. We investigated the alterations of cav-1, cav-2, nitric oxide synthases (NOS), and NO levels in human SK-N-MC neuroblastoma cells exposed to hypoxia with 2% [O2]. The major discoveries include: (i) cav-1 but not cav-2 was up-regulated in the cells exposed to 15 h of hypoxia; (ii) NO donor 1-[N, N-di-(2-aminoethyl) amino] diazen-1-ium-1, 2-diolate up-regulated the expression of cav-1, whereas the non-selective NOS inhibitor N(G)-nitro-L-arginine methyl ester and inducible NOS (iNOS) inhibitor 1400W each abolished the increase in cav-1 expression in the hypoxic SK-N-MC cells. These results suggest that iNOS-induced NO production contributes to the up-regulation of cav-1 in the hypoxic SK-N-MC cells. Furthermore, we studied the roles played by cav-1 in regulating NO, NOS, and apoptotic cell death in the SK-N-MC cells subjected to 15 h of hypoxic treatment. Both cav-1 transfection and cav-1 scaffolding domain peptide abolished the induction of iNOS, reduced the production of NO, and reduced the rates of apoptotic cell death in the hypoxic SK-N-MC cells. These results suggest that increased expression of cav-1 in response to hypoxic stimulation could prevent oxidative injury induced by reactive oxygen species. The interactions of cav-1, NO, and NOS could be an important signal pathway in protecting the neuroblastoma cells from oxidative injury, contributing to the hypoxic tolerance of neuroblastoma cells.     

Human cytidine deaminase APOBEC3H restricts HIV-1 replication

The human genome encodes seven APOBEC3 (A3) cytidine deaminases with potential antiretroviral activity: A3A, A3B, A3C, A3DE, A3F, A3G, and A3H. A3G was the first identified to block replication of human immunodeficiency virus type 1 (HIV-1) and many other retroviruses. A3F, A3B, and A3DE were shown later to have similar activities. HIV-1 produces a protein called Vif that is able to neutralize the antiretroviral activities of A3DE, A3F, and A3G, but not A3B. Only the antiretroviral activity of A3H remains to be defined due to its poor expression in cell culture. Here, we studied the mechanism impairing A3H expression. When primate A3H sequences were compared, a premature termination codon was identified on the fifth exon of the human and chimpanzee A3H genes, which significantly decreased their protein expression. It causes a 29-residue deletion from the C terminus, and this truncation did not reduce human A3H protein stability. However, the mRNA levels of the truncated gene were significantly decreased. Human A3H protein expression could be restored to a normal level either by repairing this truncation or through expression from a vector containing an intron from human cytomegalovirus. Once expression was optimized, human A3H could reduce HIV-1 infectivity up to 150-fold. Importantly, HIV-1 Vif failed to neutralize A3H activity. Nevertheless, extensive sequence analysis could not detect any significant levels of G-to-A mutation in the HIV-1 genome by human A3H. Thus, A3H inhibits HIV-1 replication potently by a cytidine deamination-independent mechanism, and optimizing A3H expression in vivo should represent a novel therapeutic strategy for HIV-1 treatment.     

Laminar shear stress inhibits lipid peroxidation induced by high glucose plus arachidonic acid in endothelial cells

Elevated blood glucose and free fatty acids induce oxidative stress associated with the incidence of cardiovascular disease. In contrast, laminar shear stress (LSS) plays a critical role in maintaining vascular health. The present study examined the mechanism for the antioxidant effect of LSS attenuating the oxidative stress induced by high glucose (HG) and arachidonic acid (AA) in human umbilical vein endothelial cells. HG and AA synergistically decreased cell viability and increased glutathione (GSH) oxidation and lipid peroxidation. The lipid peroxidation was markedly prevented by LSS as well as tetrahydrobiopterin (BH4) and GSH. LSS increased BH4 and GSH contents, and expression of GTP cyclohydrolase-1 and glutamylcysteine ligase (GCL) involved in their biosynthesis. Inhibition of GCL activity by DL-buthionine-(S,R)-sulfoximine and small-interfering RNA-mediated knockdown of GCL lessened the antioxidant effect of LSS. Therefore, it is suggested that LSS enhances antioxidant capacity of endothelial cells and thereby attenuates the oxidative stress caused by cardiovascular risk factors.