Lamotrigine analysis in blood and brain by high-performance liquid chromatography

A reversed-phase high-performance liquid chromatography assay was developed and validated to determine plasma and brain lamotrigine concentrations allowing pharmacokinetic-pharmacodynamic studies of this new antiepileptic drug in patients and laboratory animals. Lamotrigine and its internal standard were extracted, under alkaline conditions, from plasma and brain homogenate, into ethyl acetate; brain proteins were previously precipitated with trichloroacetic acid. The method was linear between 0.1 and 15.0 mg/l for plasma, with a detection limit of 0.008 mg/l, and between 0.1 and 5.0 mg/l for brain homogenate, with a detection limit of 0.023 mg/l. The method proved to be simple, useful and appropriate, not only for clinical and experimental research, but also for routine monitoring of lamotrigine concentrations in patients.http://www.sciencedirect.com/science/article/B6TG9-42T4DX1-G/1/114ff1c7668d24d37232dc1f255aeb1

(CCUG)n RNA toxicity in a Drosophila model of myotonic dystrophy type 2 (DM2) activates apoptosis

The myotonic dystrophies are prototypic toxic RNA gain-of-function diseases. Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are caused by different unstable, noncoding microsatellite repeat expansions - (CTG)DM1 in DMPK and (CCTG)DM2 in CNBP Although transcription of mutant repeats into (CUG)DM1 or (CCUG)DM2 appears to be necessary and sufficient to cause disease, their pathomechanisms remain incompletely understood. To study the mechanisms of (CCUG)DM2 toxicity and develop a convenient model for drug screening, we generated a transgenic DM2 model in the fruit fly Drosophila melanogaster with (CCUG)n repeats of variable length (n=16 and 106). Expression of noncoding (CCUG)106, but not (CCUG)16, in muscle and retinal cells led to the formation of ribonuclear foci and mis-splicing of genes implicated in DM pathology. Mis-splicing could be rescued by co-expression of human MBNL1, but not by CUGBP1 (CELF1) complementation. Flies with (CCUG)106 displayed strong disruption of external eye morphology and of the underlying retina. Furthermore, expression of (CCUG)106 in developing retinae caused a strong apoptotic response. Inhibition of apoptosis rescued the retinal disruption in (CCUG)106 flies. Finally, we tested two chemical compounds that have shown therapeutic potential in DM1 models. Whereas treatment of (CCUG)106 flies with pentamidine had no effect, treatment with a PKR inhibitor blocked both the formation of RNA foci and apoptosis in retinae of (CCUG)106 flies. Our data indicate that expression of expanded (CCUG)DM2 repeats is toxic, causing inappropriate cell death in affected fly eyes. Our Drosophila DM2 model might provide a convenient tool for in vivo drug screening

Evaluación y rehabilitación neuropsicológica en oncología pediátrica.

Objetivo. El presente trabajo tiene como objetivo el estudio de los efectos neuropsicológicos a largo plazo del cáncer infantil y sus tratamientos así como plantear propuestas para la rehabilitación cognitiva. Método. El método ha consistido en una revisión sistemática de los resultados en la literatura científica acerca de los efectos de la quimioterapia y la radioterapia sobre el SNC y en las funciones cognitivas y conductuales detectados a través de estudios de neuroimagen como calcificaciones y cambios en la sustancia blanca. Presentamos, además, el protocolo de evaluación neuropsicológica ejemplificado con un diagnóstico frecuente que presenta deterioro generalizado. Proponemos un programa de rehabilitación neuropsicológica basado en el Attention Process Training (APT) de Mateer y Sohlberg. Resultado. La radioterapia craneal y el metotrexato producen alteraciones generalizadas que se reflejan en déficit neuropsicológicos: CI, atención, memoria, habilidades académicas y motoras. Conclusiones. El avance en los tratamientos ha supuesto la disminución del número e intensidad de las secuelas. No obstante, sigue siendo frecuente que en los tumores del SNC y en las leucemias aparezcan alteraciones cognitivas y conductuales. La evaluación neuropsicológica continua y los modelos de sustancia blanca nos ayudan a entender estos efectos a largo plazo. Asimismo, esta evaluación es fundamental para diagnosticar los déficit evitando falsas atribuciones y expectativas inadecuadas. Destacamos la necesidad de una unidad de seguimiento y del trabajo interdisciplinario para promover la calidad de vida de los niños con cáncer

Absence of MutSβ leads to the formation of slipped-DNA for CTG/CAG contractions at primate replication forks

Typically disease-causing CAG/CTG repeats expand, but rare affected families can display high levels of contraction of the expanded repeat amongst offspring. Understanding instability is important since arresting expansions or enhancing contractions could be clinically beneficial. The MutSβ mismatch repair complex is required for CAG/CTG expansions in mice and patients. Oddly, by unknown mechanisms MutSβ-deficient mice incur contractions instead of expansions. Replication using CTG or CAG as the lagging strand template is known to cause contractions or expansions respectively; however, the interplay between replication and repair leading to this instability remains unclear. Towards understanding how repeat contractions may arise, we performed in vitro SV40-mediated replication of repeat-containing plasmids in the presence or absence of mismatch repair. Specifically, we separated repair from replication: Replication mediated by MutSβ- and MutSα-deficient human cells or cell extracts produced slipped-DNA heteroduplexes in the contraction- but not expansion-biased replication direction. Replication in the presence of MutSβ disfavoured the retention of replication products harbouring slipped-DNA heteroduplexes. Post-replication repair of slipped-DNAs by MutSβ-proficient extracts eliminated slipped-DNAs. Thus, a MutSβ-deficiency likely enhances repeat contractions because MutSβ protects against contractions by repairing template strand slip-outs. Replication deficient in LigaseI or PCNA-interaction mutant LigaseI revealed slipped-DNA formation at lagging strands. Our results reveal that distinct mechanisms lead to expansions or contractions and support inhibition of MutSβ as a therapeutic strategy to enhance the contraction of expanded repeats

Impact of information letters on the reporting rate of adverse drug reactions and the quality of the reports: a randomized controlled study

BACKGROUND: Spontaneous reporting of adverse drug reactions (ADRs) is an important method for pharmacovigilance, but under-reporting and poor quality of reports are major limitations. The aim of this study was to evaluate if repeated one-page ADR information letters affect (i) the reporting rate of ADRs and (ii) the quality of the ADR reports. METHODS: All 151 primary healthcare units in the Region Västra Götaland, Sweden, were randomly allocated (1:1) to an intervention (n = 77) or a control group (n = 74). The intervention consisted of one-page ADR information letters administered at three occasions during 2008 to all physicians and nurses in the intervention units. The number of ADR reports received from the 151 units was registered, as was the quality of the reports, which was defined as high if the ADR was to be reported according to Swedish regulations, that is, if the ADR was (i) serious, (ii) unexpected, and/or (iii) related to the use of new drugs and not labelled as common in the Summary of Product Characteristics. A questionnaire was administered to evaluate if the ADR information letter had reached the intended recipient. RESULTS: Before the intervention, no significant differences in reporting rate or number of high quality reports could be detected between the randomization groups. In 2008, 79 reports were sent from 37 intervention units and 52 reports from 30 control units (mean number of reports per unit ± standard deviation: 1.0 ± 2.5 vs. 0.7 ± 1.2, P = 0.34). The number of high quality reports was higher in intervention units than in control units (37 vs. 15 reports, 0.5 ± 0.9 vs. 0.2 ± 0.6, P = 0.048). According to the returned questionnaires (n = 1,292, response rate 57%), more persons in the intervention than in the control group had received (29% vs. 19%, P < 0.0001) and read (31% vs. 26%, P < 0.0001) an ADR information letter. CONCLUSIONS: This study suggests that repeated ADR information letters to physicians and nurses do not increase the ADR reporting rate, but may increase the number of high quality reports

Impact of information letters on the reporting rate of adverse drug reactions and the quality of the reports: a randomized controlled study

BACKGROUND: Spontaneous reporting of adverse drug reactions (ADRs) is an important method for pharmacovigilance, but under-reporting and poor quality of reports are major limitations. The aim of this study was to evaluate if repeated one-page ADR information letters affect (i) the reporting rate of ADRs and (ii) the quality of the ADR reports. METHODS: All 151 primary healthcare units in the Region Västra Götaland, Sweden, were randomly allocated (1:1) to an intervention (n = 77) or a control group (n = 74). The intervention consisted of one-page ADR information letters administered at three occasions during 2008 to all physicians and nurses in the intervention units. The number of ADR reports received from the 151 units was registered, as was the quality of the reports, which was defined as high if the ADR was to be reported according to Swedish regulations, that is, if the ADR was (i) serious, (ii) unexpected, and/or (iii) related to the use of new drugs and not labelled as common in the Summary of Product Characteristics. A questionnaire was administered to evaluate if the ADR information letter had reached the intended recipient. RESULTS: Before the intervention, no significant differences in reporting rate or number of high quality reports could be detected between the randomization groups. In 2008, 79 reports were sent from 37 intervention units and 52 reports from 30 control units (mean number of reports per unit ± standard deviation: 1.0 ± 2.5 vs. 0.7 ± 1.2, P = 0.34). The number of high quality reports was higher in intervention units than in control units (37 vs. 15 reports, 0.5 ± 0.9 vs. 0.2 ± 0.6, P = 0.048). According to the returned questionnaires (n = 1,292, response rate 57%), more persons in the intervention than in the control group had received (29% vs. 19%, P < 0.0001) and read (31% vs. 26%, P < 0.0001) an ADR information letter. CONCLUSIONS: This study suggests that repeated ADR information letters to physicians and nurses do not increase the ADR reporting rate, but may increase the number of high quality reports

MSH3 polymorphisms and protein levels affect CAG repeat instability in huntington's disease mice

Expansions of trinucleotide CAG/CTG repeats in somatic tissues are thought to contribute to ongoing disease progression through an affected individual's life with Huntington's disease or myotonic dystrophy. Broad ranges of repeat instability arise between individuals with expanded repeats, suggesting the existence of modifiers of repeat instability. Mice with expanded CAG/CTG repeats show variable levels of instability depending upon mouse strain. However, to date the genetic modifiers underlying these differences have not been identified. We show that in liver and striatum the R6/1 Huntington's disease (HD) (CAG)~100 transgene, when present in a congenic C57BL/6J (B6) background, incurred expansion-biased repeat mutations, whereas the repeat was stable in a congenic BALB/cByJ (CBy) background. Reciprocal congenic mice revealed the Msh3 gene as the determinant for the differences in repeat instability. Expansion bias was observed in congenic mice homozygous for the B6 Msh3 gene on a CBy background, while the CAG tract was stabilized in congenics homozygous for the CBy Msh3 gene on a B6 background. The CAG stabilization was as dramatic as genetic deficiency of Msh2. The B6 and CBy Msh3 genes had identical promoters but differed in coding regions and showed strikingly different protein levels. B6 MSH3 variant protein is highly expressed and associated with CAG expansions, while the CBy MSH3 variant protein is expressed at barely detectable levels, associating with CAG stability. The DHFR protein, which is divergently transcribed from a promoter shared by the Msh3 gene, did not show varied levels between mouse strains. Thus, naturally occurring MSH3 protein polymorphisms are modifiers of CAG repeat instability, likely through variable MSH3 protein stability. Since evidence supports that somatic CAG instability is a modifier and predictor of disease, our data are consistent with the hypothesis that variable levels of CAG instability associated with polymorphisms of DNA repair genes may have prognostic implications for various repeat-associated diseases

MutLα heterodimers modify the molecular phenotype of Friedreich ataxia

This article has been made available through the Brunel Open Access Publishing Fund.Background: Friedreich ataxia (FRDA), the most common autosomal recessive ataxia disorder, is caused by a dynamic GAA repeat expansion mutation within intron 1 of FXN gene, resulting in down-regulation of frataxin expression. Studies of cell and mouse models have revealed a role for the mismatch repair (MMR) MutS-heterodimer complexes and the PMS2 component of the MutLα complex in the dynamics of intergenerational and somatic GAA repeat expansions: MSH2, MSH3 and MSH6 promote GAA repeat expansions, while PMS2 inhibits GAA repeat expansions. Methodology/Principal Findings: To determine the potential role of the other component of the MutLα complex, MLH1, in GAA repeat instability in FRDA, we have analyzed intergenerational and somatic GAA repeat expansions from FXN transgenic mice that have been crossed with Mlh1 deficient mice. We find that loss of Mlh1 activity reduces both intergenerational and somatic GAA repeat expansions. However, we also find that loss of either Mlh1 or Pms2 reduces FXN transcription, suggesting different mechanisms of action for Mlh1 and Pms2 on GAA repeat expansion dynamics and regulation of FXN transcription. Conclusions/Significance: Both MutLα components, PMS2 and MLH1, have now been shown to modify the molecular phenotype of FRDA. We propose that upregulation of MLH1 or PMS2 could be potential FRDA therapeutic approaches to increase FXN transcription. © 2014 Ezzatizadeh et al.This article has been made available through the Brunel Open Access Publishing Fund

Excess of Rare Missense Variants in Hearing Loss Genes in Sporadic Meniere Disease

Meniere’s disease (MD) is a clinical spectrum of rare disorders characterized by vertigo attacks, associated with sensorineural hearing loss (SNHL) and tinnitus involving low to medium frequencies. Although it shows familial aggregation with incomplete phenotypic forms and variable expressivity, most cases are considered sporadic. The aim of this study was to investigate the burden for rare variation in SNHL genes in patients with sporadic MD. We conducted a targeted-sequencing study including SNHL and familial MD genes in 890 MD patients to compare the frequency of rare variants in cases using three independent public datasets as controls. Patients with sporadic MD showed a significant enrichment of missense variants in SNHL genes that was not found in the controls. The list of genes includes GJB2, USH1G, SLC26A4, ESRRB, and CLDN14. A rare synonymous variant with unknown significance was found in the MARVELD2 gene in several unrelated patients with MD. There is a burden of rare variation in certain SNHL genes in sporadicMD. Furthermore, the interaction of common and rare variants in SNHL genes may have an additive effect on MD phenotype. This study will contribute to design a gene panel for the genetic diagnosis of MD.This study was funded by FPS-PI0496-2014 and EF-0247- 2017 from Consejeria de Salud, Spain, 2016-MeniereSociety Grant, UK and Luxembourg National Research Fund (INTER/Mobility/17/11772209)

DNA repair pathways underlie a common genetic mechanism modulating onset in polyglutamine diseases

Objective: The polyglutamine diseases, including Huntington’s disease (HD) and multiple spinocerebellar ataxias (SCAs), are amongst the commonest hereditary neurodegenerative diseases. They are caused by expanded CAG tracts, encoding glutamine, in different genes. Longer CAG repeat tracts are associated with earlier ages at onset, but this does not account for all of the difference, and the existence of additional genetic modifying factors has been suggested in these diseases. A recent GWAS in HD found association between age at onset and genetic variants in DNA repair pathways and we therefore tested whether the modifying effects of variants in DNA repair genes have wider effects in the polyglutamine diseases. Methods: We assembled an independent cohort of 1462 subjects with HD and polyglutamine SCAs, and genotyped SNPs selected from the most significant hits in the HD study. Results: In the analysis of DNA repair genes as a group, we found the most significant association with age at onset when grouping all polyglutamine diseases (HD+SCAs, p=1.43x10-5). In individual SNP analysis, we found significant associations for rs3512 in FAN1 with HD+SCAs (p=1.52x10-5) and All SCAs (p=2.22x10-4) and rs1805323 in PMS2 with HD+SCAs (p=3.14x10-5), all in the same direction as in the HD GWAS. Interpretation: We show that DNA repair genes significantly modify the age at onset in HD and SCAs, suggesting a common pathogenic mechanism, which could operate through the observed somatic expansion of repeats that can be modulated by genetic manipulation of DNA repair in disease models. This offers novel therapeutic opportunities in multiple diseases