Enzyme-catalyzed modification of poly(ethersulfone) membranes

The robustness of a membrane is determined by the properties of the base polymer and the functionality of its surface. One of the most popular polymers used for membrane preparation is polyethersulfone (PES), which has excellent thermo-physical properties, but the surface properties are in need of improvement to reduce membrane fouling by adsorption of e.g. protein and live cells, which cause sever flux decline during filtration. Therefore, it is not strange that a wide range of modification methods has been published to reduce surface hydrophobicity of PES membranes. However, the methods that are currently suggested are all rather offer random control over the resulting surface structure and may be environmentally adverse This study presents enzyme-initiated grafting of PES membranes as the first successful example of an environmentally friendly modification of PES membranes. Various phenolic acids, such as 4-hydroxybenzoic acid and gallic acid (3,4,5-trihydroxybenzoic acid), were coupled to the membrane in aqueous medium at room temperature using laccase from Trametes versicolor as catalyst. This enzyme is able to oxidize phenolic compounds to their corresponding free radicals that are subsequently grafted onto PES membranes, introducing polar groups (OH, COOH) on the membrane surface by formation of a covalent C-O linkage as was proven by spin density calculations and IRRAS. We succeed in altering the surface properties of PES membranes using laccase-catalyzed modification method. It was found that the surface structure or shape that can be tuned through both the modification conditions and the modifier structure, has a significant role in prevention of adsorption rather than surface hydrophilicity as is often assumed. Membrane flux is hardly influenced (10% reduction), and foulant (e.g., bovine serum albumin, dextrin, tannin, and pathogenic bacterium Listeriamonocytogenes) repellence is greatly increased. In conclusion, the enzyme-catalyzed modification method shows a remarkable flexibility, and allows careful tuning of the membrane properties in such a way that membrane fouling can be suppressed. Besides, the modification method does not influence the bulk properties of the membrane adversely, the modification layer is resistant to a wide range of pH, and the costs of this modification on industrial scale are reasonable, which makes this modification method an interesting eco-friendly alternative to currently used methods.</p

Chicory abrogates oxidative stress, inflammation and caspase-dependent apoptosis in acute hepatic injury model induced by acetaminophen in rats

In this study the protective effect of chicory leaves hydroalcoholic extract (CIE) against acute liver injury induced by a single dose of acetaminophen (700 mg/kg, i.p.) was investigated in rats. The CIE and silymarin treatment (standard reference) were given in a dose of (100 mg/kg, p.o.) for 3 days before and at 1 and 12 h following acetaminophen administration. Treatment with CIE significantly reduced the levels of serum ALT, AST, alkaline phosphatase, bilirubin, total cholesterol, triglycerides, urea, creatinine, TNF-α and hepatic contents of malondialdehyde (MDA), nitric oxide, caspase-3 and hydroxyproline, with significant increases in serum total protein, albumin, HDL- cholesterol and hepatic activities of reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) as compared with the acetaminophen group. The histopathological alterations mediated by acetaminophen were ameliorated by CIE. It was concluded that CIE protects rat liver against acetaminophen hepatotoxicity, most probably through abrogation of oxidative stress, inflammation and caspase-3 dependent apoptosis

Fragmentation channels of relativistic 7^7Be nuclei in peripheral interactions

Nuclei of $^7$Li were accelerated at the JINR Nuclotron. After the charge-exchange reaction involving these nuclei at an external target a second $^7$Be beam of energy 1.23A GeV was formed. This beam was used to expose photo-emulsion chambers. The mean free path for inelastic $^7$Be interactions in emulsion $\lambda$=14.0$\pm$0.8 cm coincides within the errors with those for $^6$Li and $^7$Li nuclei. More than 10% of the $^7$Be events are associated with the peripheral interactions in which the total charge of the relativistic fragments is equal to the charge of the $^7$Be and in which charged mesons are not produced. An unusual ratio of the isotopes is revealed in the composition of the doubly charged $^7$Be fragments: the number of $^3$He fragments is twice as large as that of $^4$He fragments. In 50% of peripheral interactions, a $^7$Be nucleus decays to two doubly charged fragments. The present paper gives the channels of the $^7$Be fragmentation to charged fragments. In 50% of events, the $^7$Be fragmentation proceeds only to charged fragments involving no emission of neutrons. Of them, the $^3$He+$^4$He channel dominates, the $^4$He+d+p and $^6$Li+pchannels constitute 10% each. Two events involving no emission of neutrons are registered in the 3-body $^3$He+t+p and $^3$He+d+d channels. The mean free path for the coherent dissociation of relativistic $^7$Be nuclei to $^3$He+$^4$He is 7$\pm$1 m. The particular features of the relativistic $^7$Be fragmentation in such peripheral interactions are explained by the $^3$He+$^4$He 2-cluster structure of the $^7$Be nucleus.Comment: 10 pages, 3 figures, 3 tables, conference: Conference on Physics of Fundamental Interactions, Moscow, Russia, 5-9 Dec 200

Compulsive features in behavioural addictions: the case of pathological gambling

Aims To describe, in the context of DSM-V, how a focus on addiction and compulsion is emerging in the consideration of pathological gambling (PG). Methods A systematic literature review of evidence for the proposed re-classification of PG as an addiction. Results Findings include: (i) phenomenological models of addiction highlighting a motivational shift from impulsivity to compulsivity associated with a protracted withdrawal syndrome and blurring of the ego-syntonic/ego-dystonic dichotomy; (ii) common neurotransmitter (dopamine, serotonin) contributions to PG and substance use disorders (SUDs); (iii) neuroimaging support for shared neurocircuitries between behavioural and substance addictions and differences between obsessivecompulsive disorder (OCD), impulse control disorders (ICDs) and SUDs; (iv) genetic findings more closely related to endophenotypic constructs such as compulsivity and impulsivity than to psychiatric disorders; (v) psychological measures such as harm avoidance identifying a closer association between SUDs and PG than with OCD; (vi) community and pharmacotherapeutic trials data supporting a closer association between SUDs and PG than with OCD. Adapted behavioural therapies, such as exposure therapy, appear applicable to OCD, PG or SUDs, suggesting some commonalities across disorders. Conclusions PG shares more similarities with SUDs than with OCD. Similar to the investigation of impulsivity, studies of compulsivity hold promising insights concerning the course, differential diagnosis and treatment of PG, SUDs, and OCD.LundbeckLundbeckServierServierCristaliaCristaliaRocheRocheSandozSandozMohegan Sun CasinoMohegan Sun CasinoNational Center for Responsible GamingNational Center for Responsible GamingAlberta Gaming Research InstituteAlberta Gaming Research InstituteNIH [R01 DA019039, R01 DA020908, RL1 AA017539, RC1 DA028279, P20 DA027844]NI

Monozygotic twins discordant for constitutive BRCA1 promoter methylation, childhood cancer and secondary cancer

We describe monozygotic twins discordant for childhood leukemia and secondary thyroid carcinoma. We used bisulfite pyrosequencing to compare the constitutive promoter methylation of BRCA1 and several other tumor suppressor genes in primary fibroblasts. The affected twin displayed an increased BRCA1 methylation (12%), compared with her sister (3%). Subsequent bisulfite plasmid sequencing demonstrated that 13% (6 of 47) BRCA1 alleles were fully methylated in the affected twin, whereas her sister displayed only single CpG errors without functional implications. This between-twin methylation difference was also found in irradiated fibroblasts and untreated saliva cells. The BRCA1 epimutation may have originated by an early somatic event in the affected twin: approximately 25% of her body cells derived from different embryonic cell lineages carry one epigenetically inactivated BRCA1 allele. This epimutation was associated with reduced basal protein levels and a higher induction of BRCA1 after DNA damage. In addition, we performed a genome-wide microarray analysis of both sisters and found several copy number variations, i.e., heterozygous deletion and reduced expression of the RSPO3 gene in the affected twin. This monozygotic twin pair represents an impressive example of epigenetic somatic mosaicism, suggesting a role for constitutive epimutations, maybe along with de novo genetic alterations in recurrent tumor development

Structural Studies of a Four-MBT Repeat Protein MBTD1

The Polycomb group (PcG) of proteins is a family of important developmental regulators. The respective members function as large protein complexes involved in establishment and maintenance of transcriptional repression of developmental control genes. MBTD1, Malignant Brain Tumor domain-containing protein 1, is one such PcG protein. MBTD1 contains four MBT repeats.We have determined the crystal structure of MBTD1 (residues 130-566aa covering the 4 MBT repeats) at 2.5 A resolution by X-ray crystallography. The crystal structure of MBTD1 reveals its similarity to another four-MBT-repeat protein L3MBTL2, which binds lower methylated lysine histones. Fluorescence polarization experiments confirmed that MBTD1 preferentially binds mono- and di-methyllysine histone peptides, like L3MBTL1 and L3MBTL2. All known MBT-peptide complex structures characterized to date do not exhibit strong histone peptide sequence selectivity, and use a "cavity insertion recognition mode" to recognize the methylated lysine with the deeply buried methyl-lysine forming extensive interactions with the protein while the peptide residues flanking methyl-lysine forming very few contacts [1]. Nevertheless, our mutagenesis data based on L3MBTL1 suggested that the histone peptides could not bind to MBT repeats in any orientation.The four MBT repeats in MBTD1 exhibits an asymmetric rhomboid architecture. Like other MBT repeat proteins characterized so far, MBTD1 binds mono- or dimethylated lysine histones through one of its four MBT repeats utilizing a semi-aromatic cage.This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the web plugin are available in Text S1

DNMT3L Modulates Significant and Distinct Flanking Sequence Preference for DNA Methylation by DNMT3A and DNMT3B In Vivo

The DNTM3A and DNMT3B de novo DNA methyltransferases (DNMTs) are responsible for setting genomic DNA methylation patterns, a key layer of epigenetic information. Here, using an in vivo episomal methylation assay and extensive bisulfite methylation sequencing, we show that human DNMT3A and DNMT3B possess significant and distinct flanking sequence preferences for target CpG sites. Selection for high or low efficiency sites is mediated by the base composition at the −2 and +2 positions flanking the CpG site for DNMT3A, and at the −1 and +1 positions for DNMT3B. This intrinsic preference reproducibly leads to the formation of specific de novo methylation patterns characterized by up to 34-fold variations in the efficiency of DNA methylation at individual sites. Furthermore, analysis of the distribution of signature methylation hotspot and coldspot motifs suggests that DNMT flanking sequence preference has contributed to shaping the composition of CpG islands in the human genome. Our results also show that the DNMT3L stimulatory factor modulates the formation of de novo methylation patterns in two ways. First, DNMT3L selectively focuses the DNA methylation machinery on properly chromatinized DNA templates. Second, DNMT3L attenuates the impact of the intrinsic DNMT flanking sequence preference by providing a much greater boost to the methylation of poorly methylated sites, thus promoting the formation of broader and more uniform methylation patterns. This study offers insights into the manner by which DNA methylation patterns are deposited and reveals a new level of interplay between members of the de novo DNMT family

Age Related Changes in NAD+ Metabolism Oxidative Stress and Sirt1 Activity in Wistar Rats

The cofactor nicotinamide adenine dinucleotide (NAD+) has emerged as a key regulator of metabolism, stress resistance and longevity. Apart from its role as an important redox carrier, NAD+ also serves as the sole substrate for NAD-dependent enzymes, including poly(ADP-ribose) polymerase (PARP), an important DNA nick sensor, and NAD-dependent histone deacetylases, Sirtuins which play an important role in a wide variety of processes, including senescence, apoptosis, differentiation, and aging. We examined the effect of aging on intracellular NAD+ metabolism in the whole heart, lung, liver and kidney of female wistar rats. Our results are the first to show a significant decline in intracellular NAD+ levels and NAD∶NADH ratio in all organs by middle age (i.e.12 months) compared to young (i.e. 3 month old) rats. These changes in [NAD(H)] occurred in parallel with an increase in lipid peroxidation and protein carbonyls (o- and m- tyrosine) formation and decline in total antioxidant capacity in these organs. An age dependent increase in DNA damage (phosphorylated H2AX) was also observed in these same organs. Decreased Sirt1 activity and increased acetylated p53 were observed in organ tissues in parallel with the drop in NAD+ and moderate over-expression of Sirt1 protein. Reduced mitochondrial activity of complex I–IV was also observed in aging animals, impacting both redox status and ATP production. The strong positive correlation observed between DNA damage associated NAD+ depletion and Sirt1 activity suggests that adequate NAD+ concentrations may be an important longevity assurance factor

Enzyme-catalyzed modification of poly(ethersulfone) membranes

The robustness of a membrane is determined by the properties of the base polymer and the functionality of its surface. One of the most popular polymers used for membrane preparation is polyethersulfone (PES), which has excellent thermo-physical properties, but the surface properties are in need of improvement to reduce membrane fouling by adsorption of e.g. protein and live cells, which cause sever flux decline during filtration. Therefore, it is not strange that a wide range of modification methods has been published to reduce surface hydrophobicity of PES membranes. However, the methods that are currently suggested are all rather offer random control over the resulting surface structure and may be environmentally adverse This study presents enzyme-initiated grafting of PES membranes as the first successful example of an environmentally friendly modification of PES membranes. Various phenolic acids, such as 4-hydroxybenzoic acid and gallic acid (3,4,5-trihydroxybenzoic acid), were coupled to the membrane in aqueous medium at room temperature using laccase from Trametes versicolor as catalyst. This enzyme is able to oxidize phenolic compounds to their corresponding free radicals that are subsequently grafted onto PES membranes, introducing polar groups (OH, COOH) on the membrane surface by formation of a covalent C-O linkage as was proven by spin density calculations and IRRAS. We succeed in altering the surface properties of PES membranes using laccase-catalyzed modification method. It was found that the surface structure or shape that can be tuned through both the modification conditions and the modifier structure, has a significant role in prevention of adsorption rather than surface hydrophilicity as is often assumed. Membrane flux is hardly influenced (10% reduction), and foulant (e.g., bovine serum albumin, dextrin, tannin, and pathogenic bacterium Listeriamonocytogenes) repellence is greatly increased. In conclusion, the enzyme-catalyzed modification method shows a remarkable flexibility, and allows careful tuning of the membrane properties in such a way that membrane fouling can be suppressed. Besides, the modification method does not influence the bulk properties of the membrane adversely, the modification layer is resistant to a wide range of pH, and the costs of this modification on industrial scale are reasonable, which makes this modification method an interesting eco-friendly alternative to currently used methods.</p