Protective Effects of Selenium and Vitamin E Combination on Experimental Colitis in Blood Plasma and Colon of Rats

Ulcerative colitis increases oxidative damage accompanied by production of free oxygen radicals. Selenium (Se) and vitamin E are two natural antioxidants. The present study was undertaken to investigate the possible protective role of Se and vitamin E combination in experimental colitis induced by acetic acid (AA) in rats. This study was carried out on three groups, namely the first (control), the second (experimental colitis group, 2 ml 5% acetic acid), and the third groups (2 ml 5% acetic acid, vitamin E (100 mg/kg body weight (bw)) plus Se (0.2 mg/kg bw)). The activities of catalase (CAT), prolidase (PRS), myeloperoxidase (MPO), total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index (OSI), total thiol (T-SH) were determined in plasma and colon samples. Macroscopic and microscopic damages in colon were increased by AA treatment (p < 0.01 and p < 0.01, respectively), whereas they were decreased by selenium and vitamin E treatment (p < 0.05 and p < 0.01, respectively). The activities of CAT and PRS in the plasma and colon were significantly affected (p < 0.05 and p < 0.01) by treatment of AA, Se, and vitamin E. MPO activity in colon was increased (p < 0.01) by AA treatment and decreased (p < 0.05) by Se and vitamin E administration. The values of TOS and OSI in plasma were increased (p < 0.5) by AA. The TAC and T-SH in colon were decreased (p < 0.05) by AA and increased (p < 0.05) by Se and vitamin E. Based upon these results, Se and vitamin E may play an important role in preventive indication of the oxidative damage associated by acetic acid caused inflammation.     

Estradiol enhances cell-associated paraoxonase 1 (PON1) activity in vitro without altering PON1 expression

PON1 is a high density lipoprotein-associated enzyme that plays an important role in organophosphate detoxification and prevention of atherosclerosis. In vivo animal and human studies have indicated that estradiol (E2) supplementation enhances serum PON1 activity. In this study, we sought to determine if E2 directly up-regulates cell-associated PON1 activity in vitro and to characterize the mechanism of regulation. In vitro E2 treatment of both the human hepatoma cell line Huh7 and normal rat hepatocytes resulted in a 2- to 3-fold increase in cell-associated PON1 catalytic activity. E2 potently induced PON1 activity with average EC₅₀ values of 15 nM for normal hepatocytes and 68 nM for Huh7. The enhancement of PON1 activity by E2 was blocked by the estrogen receptor (ER) antagonist ICI 182,780 indicating that E2 was acting through the ER. The up-regulation of PON1 activity by E2 did not involve enhancement of PON1 mRNA or protein levels and did not promote secretion of PON1. Thus, E2 can enhance cell-associated PON1 activity in vitro without altering PON1 gene expression or protein level. Our data suggest that E2 may regulate the specific activity and/or stability of cell surface PON1.     

The new HNO donor, 1-nitrosocyclohexyl acetate, increases contractile force in normal and β-adrenergically desensitized ventricular myocytes

Haplotype, which is the sequence of SNPs in a specific chromosome, plays an important role in disease association studies. However, current sequencing techniques can detect the presence of SNP sites, but they cannot tell which copy of a pair of chromosomes the alleles belong to. Moreover, sequencing errors that occurred in sequencing SNP fragments make it difficult to determine a pair of haplotypes from SNP fragments. To help overcome this difficulty, the haplotype assembly problem is defined from the viewpoint of computation, and several models are suggested to tackle this problem. However, there are no freely available web-based tools to overcome this problem as far as we are aware. In this paper, we present a web-based application based on the genetic algorithm, named HapAssembler, for assembling a pair of haplotypes from SNP fragments. Numerical results on real biological data show that the correct rate of the proposed application in this paper is greater than 95% in most cases. HapAssembler is freely available at http://alex.chonnam.ac.kr/~drminor/hapHome.htm. Users can choose any model among four models for their purpose and determine haplotypes from their input data.     

Push and pull of tropomyosin's opposite effects on myosin attachment to actin. A chimeric tropomyosin host-guest study

Tropomyosin is a ubiquitous actin-binding protein with an extended coiled-coil structure. Tropomyosin-actin interactions are weak and loosely specific, but they potently influence myosin. One such influence is inhibitory and is due to tropomyosin's statistically preferred positions on actin that sterically interfere with actin's strong attachment site for myosin. Contrastingly, tropomyosin's other influence is activating. It increases myosin's overall actin affinity ～4-fold. Stoichiometric considerations cause this activating effect to equate to an ～4(7)-fold effect of myosin on the actin affinity of tropomyosin. These positive, mutual, myosin-tropomyosin effects are absent if Saccharomyces cerevisiae tropomyosin replaces mammalian tropomyosin. To investigate these phenomena, chimeric tropomyosins were generated in which 38-residue muscle tropomyosin segments replaced a natural duplication within S. cerevisiae tropomyosin TPM1. Two such chimeric tropomyosins were sufficiently folded coiled coils to allow functional study. The two chimeras differed from TPM1 but in opposite ways. Consistent with steric interference, myosin greatly decreased the actin affinity of chimera 7, which contained muscle tropomyosin residues 228-265. On the other hand, myosin S1 increased by an order of magnitude the actin affinity of chimera 3, which contained muscle tropomyosin residues 74-111. Similarly, myosin S1-ADP binding to actin was strengthened 2-fold by substitution of chimera 3 tropomyosin for wild-type TPM1. Thus, a yeast tropomyosin was induced to mimic the activating behavior of mammalian tropomyosin by inserting a mammalian tropomyosin sequence. The data were not consistent with direct tropomyosin-myosin binding. Rather, they suggest an allosteric mechanism, in which myosin and tropomyosin share an effect on the actin filament.     

A novel statin-mediated “prenylation block-and-release” assay provides insight into the membrane targeting mechanisms of small GTPases

Ras super-family small GTPases regulate diverse cellular processes such as vesicular transport and signal transduction. Critical to these activities is the ability of these proteins to target to specific intracellular membranes. To allow association with membranes Ras-related GTPases are post-translationally modified by covalent attachment of prenyl groups to conserved cysteine residues at or near their C-terminus. Here we used the HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase (HMGCR) inhibitor mevastatin to develop a ‘prenylation block-and-release’ assay that allows membrane targeting of prenylated proteins to be visualized in living cells. Using this assay we investigated the cytosol to membrane targeting of several small GTPases to compartments of the secretory and endocytic pathways. We found that all Rabs tested were targeted directly to the membrane on which they reside at steady-state and not via an intermediate location as reported for Ras and Rho proteins. However, we observed that the kinetics of cytosol to membrane targeting differed for each Rab tested. Comparison of the mevastatin sensitivity and kinetics of membrane targeting of Rab23, Rab23 prenylation motif mutants and H-Ras revealed that these parameters are strongly dependent upon the prenyl transferase with Rab geranylgeranyl transferase substrates exhibiting higher sensitivity and requiring greater time to recover from mevastatin inhibition than farnesyl transferase substrates. We propose that this assay is a useful tool to investigate the kinetics, biological functions and the mechanisms of membrane targeting of prenylated proteins.     

A homozygous mutation in the tight-junction protein JAM3 causes hemorrhagic destruction of the brain, subependymal calcification, and congenital cataracts

The tight junction, or zonula occludens, is a specialized cell-cell junction that regulates epithelial and endothelial permeability, and it is an essential component of the blood-brain barrier in the cerebrovascular endothelium. In addition to functioning as a diffusion barrier, tight junctions are also involved in signal transduction. In this study, we identified a homozygous mutation in the tight-junction protein gene JAM3 in a large consanguineous family from the United Arab Emirates. Some members of this family had a rare autosomal-recessive syndrome characterized by severe hemorrhagic destruction of the brain, subependymal calcification, and congenital cataracts. Their clinical presentation overlaps with some reported cases of pseudo-TORCH syndrome as well as with cases involving mutations in occludin, another component of the tight-junction complex. However, massive intracranial hemorrhage distinguishes these patients from others. Homozygosity mapping identified the disease locus in this family on chromosome 11q25 with a maximum multipoint LOD score of 6.15. Sequence analysis of genes in the candidate interval uncovered a mutation in the canonical splice-donor site of intron 5 of JAM3. RT-PCR analysis of a patient lymphoblast cell line confirmed abnormal splicing, leading to a frameshift mutation with early termination. JAM3 is known to be present in vascular endothelium, although its roles in cerebral vasculature have not been implicated. Our results suggest that JAM3 is essential for maintaining the integrity of the cerebrovascular endothelium as well as for normal lens development in humans.     

Improving the <Emphasis Type="Italic">i</Emphasis>MM904 <Emphasis Type="Italic">S. cerevisiae</Emphasis> metabolic model using essentiality and synthetic lethality data

Background  

Saccharomyces cerevisiae is the first eukaryotic organism for which a multi-compartment genome-scale metabolic model was constructed. Since then a sequence of improved metabolic reconstructions for yeast has been introduced. These metabolic models have been extensively used to elucidate the organizational principles of yeast metabolism and drive yeast strain engineering strategies for targeted overproductions. They have also served as a starting point and a benchmark for the reconstruction of genome-scale metabolic models for other eukaryotic organisms. In spite of the successive improvements in the details of the described metabolic processes, even the recent yeast model (i.e., i MM904) remains significantly less predictive than the latest E. coli model (i.e., i AF1260). This is manifested by its significantly lower specificity in predicting the outcome of grow/no grow experiments in comparison to the E. coli model.     

Evidences showing wide presence of small genomic aberrations in chronic lymphocytic leukemia

Background

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the western population. Although genetic factors are considered to contribute to CLL etiology, at present genomic aberrations identified in CLL are limited compared with those identified in other types of leukemia, which raises the question of the degree of genetic influence on CLL. We performed a high-resolution genome scanning study to address this issue.

Findings

Using the restriction paired-end-based Ditag Genome Scanning technique, we analyzed three primary CLL samples at a kilobase resolution, and further validated the results in eight primary CLL samples including the two used for ditag collection. From 51,632 paired-end tags commonly detected in the three CLL samples representing 5% of the HindIII restriction fragments in the genomes, we identified 230 paired-end tags that were present in all three CLL genomes but not in multiple normal human genome reference sequences. Mapping the full-length sequences of the fragments detected by these unmapped tags in seven additional CLL samples confirmed that these are the genomic aberrations caused by small insertions and deletions, and base changes spreading across coding and non-coding regions.

Conclusions

Our study identified hundreds of loci with insertion, deletion, base change, and restriction site polymorphism present in both coding and non-coding regions in CLL genomes, indicating the wide presence of small genomic aberrations in chronic lymphocytic leukemia. Our study supports the use of a whole genome sequencing approach for comprehensively decoding the CLL genome for better understanding of the genetic defects in CLL.

     

Mental health literacy towards depression among non-medical students at a Malaysian university

Background The aim of the present study was to evaluate the knowledge and perception of depression among students of University Sains Malaysia (USM), in Penang, Peninsular Malaysia.Method Face-to-face interviews were conducted using a pre-validated 21-item questionnaire among students at USM.Results A total of 500 respondents participated in the survey comprising 24.6% (n=123) males and 75.4% (n=377) females. Half (50.0%, n=250) were Malays, followed by Chinese (44.0%, n=220) and Indians (6.0%, n=30). Whilst exploring the respondents' knowledge of the symptoms of depression, it was found that Chinese females had a comparatively better knowledge (P=0.058) of the symptoms of depression in comparison with Malays and Indians. Overall, social issues were attributed as the possible cause of depression. A cursory knowledge level was observed regarding medication for depression. Female students were more inclined towards the use of alternative and traditional medicines. However, with regard to seeking professional help, consultation with a psychiatrist was preferred by the majority.Conclusion Overall, a moderate level of knowledge about the symptoms of depression and a cursory knowledge of its therapy were observed. Those with personal experience of depression had better knowledge of the symptoms and therapy. Alternative treatments and traditional medicines were also favoured. There is a risk that this may affect the ability of Malaysian youths to seek evidence-based mental health care.     

Phenothiazines alter plasma membrane properties and sensitize cancer cells to injury by inhibiting annexin-mediated repair

Repair of damaged plasma membrane in eukaryotic cells is largely dependent on the binding of annexin repair proteins to phospholipids. Changing the biophysical properties of the plasma membrane may provide means to compromise annexin-mediated repair and sensitize cells to injury. Since, cancer cells experience heightened membrane stress and are more dependent on efficient plasma membrane repair, inhibiting repair may provide approaches to sensitize cancer cells to plasma membrane damage and cell death. Here, we show that derivatives of phenothiazines, which have widespread use in the fields of psychiatry and allergy treatment, strongly sensitize cancer cells to mechanical-, chemical-, and heat-induced injury by inhibiting annexin-mediated plasma membrane repair. Using a combination of cell biology, biophysics, and computer simulations, we show that trifluoperazine acts by thinning the membrane bilayer, making it more fragile and prone to ruptures. Secondly, it decreases annexin binding by compromising the lateral diffusion of phosphatidylserine, inhibiting the ability of annexins to curve and shape membranes, which is essential for their function in plasma membrane repair. Our results reveal a novel avenue to target cancer cells by compromising plasma membrane repair in combination with noninvasive approaches that induce membrane injuries.