Serotonin and catecholaminergic polymorphic ventricular tachycardia: a possible therapeutic role for SSRIs?

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare malignant arrhythmia, usually diagnosed in the adolescent years. The diagnosis can typically be made by one or more of the following: a positive family history, exercise electrocardiography, ambulatory ECG monitoring and/ or an intra-cardiac, electrophysiological examination. This is a case report of a patient with CPVT that was refractory to treatment with beta-blockade and an implanted automatic cardioverter defibrillator. However, after a selective serotonin re-uptake inhibitor (SSRI) was added to the therapeutic regimen, no further episodes of ventricular tachycardia occurred during the following two years.

Effect of abstinence challenge on brain function and cognition in smokers differs by COMT genotype

The val allele of the catechol-O-methyltransferase (COMT) val(158)met polymorphism has been linked with nicotine dependence and with cognitive performance in healthy volunteers. We tested the hypothesis that the val allele is a risk factor for altered brain function and cognition during nicotine abstinence as compared with the normal smoking state. Chronic smokers (n=33) were genotyped prospectively for the COMT polymorphism for balanced selection of met/met, val/met and val/val groups. A visual N-back working memory task was performed during two separate blood oxygen level-dependent (BOLD) functional magnetic resonance imaging sessions in counterbalanced order: (1) smoking as usual, and (2)>or=14 h confirmed abstinence. Significant genotype by session interactions were observed for BOLD signal in right dorsolateral prefrontal cortex (DLPFC; (P=0.0005), left DLPFC (P=0.02) and dorsal cingulate/medial prefrontal cortex (P=0.01) as well as for task reaction time (P=0.03). Smokers with val/val genotypes were more sensitive to the abstinence challenge than carriers of the met allele, with the greatest effects on BOLD signal and performance speed at the highest working memory load. These data suggest a novel brain-behavior mechanism that may underlie the increased susceptibility to nicotine dependence and smoking relapse associated with the COMT val allele. Exploration of the effects of COMT inhibitors as a possible smoking cessation aid in this group may be warranted.

The OptIPuter microscopy demonstrator: enabling science through a transatlantic lightpath

The OptIPuter microscopy demonstrator project has been designed to enable concurrent and remote usage of world-class electron microscopes located in Oxford and San Diego. The project has constructed a network consisting of microscopes and computational and data resources that are all connected by a dedicated network infrastructure using the UK Lightpath and US Starlight systems. Key science drivers include examples from both materials and biological science. The resulting system is now a permanent link between the Oxford and San Diego microscopy centres. This will form the basis of further projects between the sites and expansion of the types of systems that can be remotely controlled, including optical, as well as electron, microscopy. Other improvements will include the updating of the Microsoft cluster software to the high performance computing (HPC) server 2008, which includes the HPC basic profile implementation that will enable the development of interoperable clients.

Molecular cloning and mRNA expression profiling of the first specific jasmonate biosynthetic pathway gene allene oxide synthase from Hyoscyamus niger

In the endeavor to enhance the production of pharmaceutically valuable tropane alkaloids including hyoscyamine and scopolamine in Hyoscyamus niger, methyl jasmonate (MeJA) showed significant stimulation both in tropane biosynthetic pathway enzymes activities and tropane alkaloids yields. Therefore it was speculated that genetic engineering of jasmonate biosynthetic pathway might enhance the endogenous jasmonate concentration, followed by stimulating the production of tropane alkaloids. Herein a full-length cDNA encoding allene oxide synthase (AOS, EC 4.2.1.92), the first committed step enzyme in jasmonate biosynthetic pathway was reported (named HnAOS, GenBank accession: EF532599). HnAOS was a novel member of the cytochrome P450 (CYP74A) subfamily. Real-time quantitative PCR analysis showed that HnAOS mRNA accumulated mainly in stems, and responded significantly to wounding or methyl jasmonate.

A new endophytic taxane-production fungus from Taxus chinensis

More than 50 kinds of endophytic fungi associated with Taxus chinensis, were isolated and examined as potential source of the imposing anticancer drug taxol. Of these, 4 isolates show ability to produce taxane when measured with the competitive inhibition enzyme immunoassay method. The most promising clone, DA10, identified as Mucor rouxianus sp., is the first rouxianus reported as taxol-production fungus. The presence of taxol and its important precursors, such as 10-diacetyl baccatinIII (10-DAB) and baccatinIII, in the culture of this fungus was confirmed by reactivity with taxane-specific monoclonal antibody, comparative chromatographic and mass spectrometric behavior, cytotoxity to liver carcinoma 7402, and molecular cloning of kernel fragment of taxadiene synthase gene.

[Molecular cloning and expression profile of a jasmonate biosynthetic pathway gene allene oxide cyclase from Hyoscyamus niger]

Hyoscyamus niger L. is a medicinal plant which produces a class of jasmonate-responsive pharmaceutical secondary metabolites named as tropane alkaloids. As a family of signaling phytohormones, jasmonates play significant roles in the biosynthesis of many plant secondary metabolites. In jasmonate biosynthetic pathway of plants, allene oxide cyclase (AOC, [...] EC 5.3.99.6 [...]) catalyzes the most important step. Here we cloned a cDNA from H. niger, named HnAOC (GenBank accession: AY708383), which was 1044 bp long, with a 747 bp open reading frame (ORF) encoding a polypeptide of 248 amino acid residues. Southern blot analysis indicated that it was a multi-copy gene. RT-PCR analysis revealed that the expression of HnAOC was regulated by various stresses and elicitors, with methyl-jasmonate showing the most prominent inducement. The characterization of HnAOC would be helpful for improving the production of valuable secondary metabolites by regulating the biosynthesis ofjasmonates.

Identification and analysis of genomic regions with large between-population differentiation in humans

The primary aim of genetic association and linkage studies is to identify genetic variants that contribute to phenotypic variation within human populations. Since the overwhelming majority of human genetic variation is found within populations, these methods are expected to be effective and can likely be extrapolated from one human population to another. However, they may lack power in detecting the genetic variants that contribute to phenotypes that differ greatly between human populations. Phenotypes that show large differences between populations are expected to be associated with genomic regions exhibiting large allele frequency differences between populations. Thus, from genome-wide polymorphism data genomic regions with large allele frequency differences between populations can be identified, and evaluated as candidates for large between-population phenotypic differences. Here we use allele frequency data from approximately 1.5 million SNPs from three human populations, and present an algorithm that identifies genomic regions containing SNPs with extreme Fst. We demonstrate that our candidate regions have reduced heterozygosity in Europeans and Chinese relative to African-Americans, and are likely enriched with genes that have experienced positive natural selection. We identify genes that are likely responsible for phenotypes known to differ dramatically between human populations and present several candidates worthy of future investigation. Our list of high Fst genomic regions is a first step in identifying the genetic variants that contribute to large phenotypic differences between populations, many of which have likely experienced positive natural selection. Our approach based on between population differences can compliment traditional within population linkage and association studies to uncover novel genotype-phenotype relationships.

Bioactive natural products from endophytes: a review

Endophytes, microorganisms that reside in the internal tissues of living plants without causing any immediate overt negative effects, have been found in every plant species examined to date and recognized as potential sources of novel natural products for exploitation in medicine, agriculture, and industry with more and more bioactive natural products isolated from the microorganisms. In this review, we focus mainly on bioactive natural products from endophytic microorganisms by their different functional roles. The prospect and facing problems of isolating natural products from endophytes are also discussed.

Screening of taxol-producing endophytic fungi from Taxus chinensis var. mairei

A total of 38 endophytic fungus strains were isolated from Taxus chinensis var. mairei by aseptic technique. Genomic DNA was extracted from isolated endophytic fungi and subjected to polymerase chain reaction (PCR) analysis for the presence of Taxus taxadiene synthase (TS) gene, a rate-limiting enzyme gene in the taxol biosynthetic pathway. Twelve out of 38 isolated endophytic fungus strains showed PCR positive for the ts gene. Subsequently, taxol and its related compounds were extracted from culture filtrates and mycelia of the PCR positive strains, separated by column chromatography and analyzed by High Performance Liquid Chromatography and Mass Spectrum. The analysis result showed that 3 strains could produce taxol and its related compounds at the detectible level. This study indicates that molecular detection of the ts gene is an efficient method for primary screening of taxol or its related compounds-producing endophytic fungi which can improve prominently screening efficiency.

Conformal thermal therapy using planar ultrasound transducers and adaptive closed-loop MR temperature control: demonstration in gel phantoms andex vivotissues

MRI-guided transurethral ultrasound therapy offers a minimally invasive approach for the treatment of localized prostate cancer. Integrating a multi-element planar transducer with active MR temperature feedback can enable three-dimensional conformal thermal therapy of a target region within the prostate gland while sparing surrounding normal tissues. Continuous measurement of the temperature distribution in tissue enables dynamic compensation for unknown changes in blood flow and tissue properties during treatment. The main goal of this study was to evaluate the feasibility of using active temperature feedback on a clinical 1.5 T MR imager for conformal thermal therapy. MR thermometry was performed during heating in both gel phantoms and excised tissue with a transurethral heating applicator, and the rotation rate and power were varied based on the thermal measurements. The capability to produce a region of thermal damage that matched a target boundary was evaluated. The influence of a cooling gradient (to simulate cooling of the rectum or urethra) on the desired pattern of thermal damage was also investigated in gel phantoms. Results showed high correlation between the desired target boundary and the 55 degrees C isotherm generated during heating with an average distance error of 0.9 mm +/- 0.4 mm (n = 6) in turkey breasts, 1.4 mm +/- 0.6 mm (n = 4) in gel phantoms without rectal cooling and 1.4 mm +/- 0.6 mm (n = 3) in gel phantoms with rectal cooling. The results were obtained using a temporal update rate of 5 s, a spatial resolution of 3 x 3 x 10 mm for the control point, and a temperature uncertainty of approximately 1 degrees C. The performance of the control algorithm under these conditions was comparable to that of simulations conducted previously by our group. Overall, the feasibility of generating targeted regions of thermal damage with a transurethral heating applicator and active MR temperature feedback has been demonstrated experimentally. This method of treatment appears capable of accounting for unpredictable and varying tissue properties during the treatment.