Abolition of valproate-derived choleresis in the Mrp2 transporter-deficient rat

Valproic acid (VPA) is a major therapeutic agent in the treatment of epilepsy and other neurological disorders. It is metabolized in humans and rats primarily along two pathways: direct glucuronidation to yield the acyl glucuronide (VPA-G) and beta-oxidation. We have shown much earlier in the Sprague-Dawley rat that i.v. administration of sodium valproate (NaVPA) caused a marked choleresis ( mean of 3.3 times basal bile flow after doses of 150 mg/kg), ascribed to the passive osmotic flow of bile water following excretion of VPA-G across the canalicular membrane. Active biliary pumping of anionic drug conjugates across the canalicular membrane is now believed to be attributable to transporter proteins, in particular Mrp2, which is deficient in the TR- ( a mutant Wistar) rat. In the present study, normal Wistar and Mrp2-deficient TR- rats were dosed i.v. with NaVPA at 150 mg/kg. In the Wistar rats, there was a peak choleretic effect of about 3.2 times basal bile flow, occurring at about 30 to 45 min postdose ( as seen previously with Sprague-Dawley rats). In TR- rats given the same i.v. dose, there was no evidence of postdose choleresis. The choleresis was correlated with the excretion of VPA-G into bile. In Wistar rats, 62.8 +/- 7.7% of the NaVPA dose was excreted in bile as VPA-G, whereas in TR- rats, only 2.0 +/- 0.6% of the same dose was excreted as VPA-G in bile ( with partial compensatory excretion of VPA-G in urine). This study underlines the functional ( bile flow) consequences of biliary transport of xenobiotic conjugated metabolites.

Differentiating human NT2/D1 neurospheres as a versatile in vitro 3D model system for developmental neurotoxicity testing

Developmental neurotoxicity is a major issue in human health and may have lasting neurological implications. In this preliminary study we exposed differentiating Ntera2/clone D1 (NT2/D1) cell neurospheres to known human teratogens classed as non-embryotoxic (acrylamide), weakly embryotoxic (lithium, valproic acid) and strongly embryotoxic (hydroxyurea) as listed by European Centre for the Validation of Alternative Methods (ECVAM) and examined endpoints of cell viability and neuronal protein marker expression specific to the central nervous system, to identify developmental neurotoxins. Following induction of neuronal differentiation, valproic acid had the most significant effect on neurogenesis, in terms of reduced viability and decreased neuronal markers. Lithium had least effect on viability and did not significantly alter the expression of neuronal markers. Hydroxyurea significantly reduced cell viability but did not affect neuronal protein marker expression. Acrylamide reduced neurosphere viability but did not affect neuronal protein marker expression. Overall, this NT2/D1 -based neurosphere model of neurogenesis, may provide the basis for a model of developmental neurotoxicity in vitro.

Interacção entre ácido valpróico e meropenem: um estudo retrospectivo

Introdução: existem múltiplos estudos acerca da interacção entre o ácido valpróico (AVP) e o meropenem, mas não estão bem definidas as recomendações para o seu uso concomitante, visto haver uns que indicam que os dois fármacos não devem ser administrados juntos e outros que apenas recomendam que os níveis de valproatémia sejam monitorizados. Também não existe informação consistente sobre possíveis repercussões clínicas desta interacção. O objectivo deste estudo foi analisar a interacção entre o AVP e o meropenem e as suas repercussões clínicas, em doentes hospitalizados e cronicamente medicados com o primeiro. Material e Métodos: trata-se de um estudo retrospectivo de uma amostra de doentes internados num hospital distrital no período de um ano. Os critérios de inclusão foram a existência de pelo menos uma determinação do nível sérico de AVP na semana anterior à prescrição de meropenem e outra durante o tratamento concomitante com os dois fármacos. Foi efectuada a análise estatística de 18 episódios. Resultados: Verificou-se um declínio médio estatisticamente significativo (p<0,001) de cerca de 83,4% dos níveis séricos de AVP após o início da terapêutica com meropenem e foram objectivadas crises convulsivas em 50% dos doentes. Discussão: a interacção entre os dois fármacos em questão é potencialmente grave, sendo que o número de doentes com manifestações clínicas desta interacção é maior que em estudos semelhantes. Conclusão: concluiu-se que a utilização concomitante dos dois fármacos deve ser evitada.

Trois expositions environnementales, un trouble : perturbations endocrine, du métabolisme monocarboné, et du microbiote intestinal maternel pendant la gestation déclenchent des phénotypes de type autistique chez le rat de type sauvage

Les Troubles du Spectre Autistique (TSA) sont caractérisés par deux principaux symptômes : des difficultés de communication sociale et des comportements stéréotypés et intérêts restreints. Les TSA touchent 5 fois plus les garçons que les filles et une augmentation de la prévalence exponentielle et continue a été observée aux États-Unis ces dernières décennies. Cette augmentation ne peut s’expliquer par les facteurs génétiques à eux seuls qui ne représentent que 5 à 15% des cas de TSA. Il est donc indispensable d’identifier de potentiels facteurs de risque environnementaux des TSA. Le but de ce travail est d’étudier différents facteurs environnementaux potentiellement modifiables dans le développement de phénotypes autistiques dans différents modèles précliniques des TSA. Les objectifs spécifiques sont : (i) caractériser les effets neurocomportementaux provoqués par une exposition périnatale simultanée à 5 perturbateurs endocriniens parmi les plus prévalent dans notre environnement quotidien (DEHP, DBP, DiNP, BDE-47, BDE-99) à de faibles doses pertinentes pour l’exposition humaine, (ii) identifier les effets neurocomportementaux associés à une altération périconceptionnelle du microbiote maternelle (iii) déterminer les effets neurocomportementaux associés à une altération périconceptionnelle du métabolisme monocarboné. Les résultats présentés dans cette thèse démontrent le potentiel de chacun de ces facteurs environnementaux d’altérer le développement cérébral fœtal. Chaque condition expérimentale a provoqué l’apparition de traits autistiques chez les rats, avec des spécificités comportementales pour chaque exposition développementale. Des déficits d’interactions sociales ont été observés dans chaque situation expérimentale, associés soit à de l’anxiété, de l’hyperactivité, des altérations d’intégration sensorimotrice, et/ou des stéréotypies. Cela nous force à considérer les TSA comme une pathologie aux multiples facettes où l’hétérogénéité des tableaux cliniques est représentative de l’hétérogénéité des causes possibles. La multitude des interactions environnementales courantes possibles avec l’épigénome pourrait être à la base de la grande diversité observée dans la sévérité des symptômes et / ou des comorbidités des TSA. Ce travail ouvre des perspectives futures de prévention ciblée des TSA fondées sur de potentielles modifications de l’environnement comme la réduction de l’exposition aux perturbateurs endocriniens, ou des supplémentations en donneurs monocarbonés (e.g. acide folique) et/ou probiotiques.

Hyperprolinemia as a clue in the diagnosis of a patient with a psychiatric disorder

Background: Over the last few years, microdeletions of the 22q11.2 region responsible for DiGeorge syndrome, or velocardiofacial syndrome, have been increasingly related to neuropsychiatric disorders including schizophrenia and bipolar disorders. These signs seem to be related to certain genes located in the hemideleted region as the proline dehydrogenase (PRODH) and the catecholo-methyltransferase (COMT) genes. The PRODH or proline oxidase deficiency is responsible for hyperprolinemia type 1 (HPI) also causing psychiatric manifestations. Case Report: We describe a 17 year old boy with previous mild psychomotor and speech delay, mild cognitive impairment, and obsessive behaviours who started his adolescent psychiatric care presenting irritablemood and aggressive behaviour with schizophrenia symptoms that scored a “severely ill” level PANSS assessment. Symptoms got worse when he was treated with valproic acid and plasma aminoacids showing increase in alanine and proline, suggested a mitochondrial involvement of the proline metabolic pathway. Results: Mild dysmorphia suggested a possible 22q11.2 deletion genetically confirmed involving both the PRODH and COMT regions. HPI that can present with psychiatric features is however a recessive disorder and therefore the symptoms could not be solely explained by this genetic deletion. Additional investigations also showed disclosed a p.L289m (c.1865 T > A) mutation in the PRODH gene. Discussion: We believe that the association of this mutation together with the 22q11.2 deletion would lead to a decrease of functional protein. Although it may be difficult to diagnosis chromosomal abnormalities in patients with no clear malformations and mild dysmorphic features as in this patient we emphasize need to investigate the aetiology in patients with psychiatric symptoms, especially if they have other systemic manifestations such as developmental delay or psychotic symptoms, as it may be important in the management of the patients.

Abdominal epilepsy as an unusual cause ofabdominal pain: a case report.

Introduction: Abdominal pain, in etiology sometimes difficult to be defined, is a frequent complaint in childhood. Abdominal epilepsy is a rare cause of abdominal pain. Objectives: In this article, we report on 5 year old girl patient with abdominal epilepsy. Methods: Some investigations (stool investigation, routine blood tests, ultrasonography (USG), electrocardiogram (ECHO) and electrocardiograpy (ECG), holter for 24hr.) were done to understand the origin of these complaints; but no abnormalities were found. Finally an EEG was done during an episode of abdominal pain and it was shown that there were generalized spikes especially precipitated by hyperventilation. The patient did well on valproic acid therapy and EEG was normal 1 month after beginning of the treatment. Discussion: The cause of chronic recurrent paroxymal abdominal pain is difficult for the clinicians to diagnose in childhood. A lot of disease may lead to paroxysmal gastrointestinal symptoms like familial mediterranean fever and porfiria. Abdominal epilepsy is one of the rare but easily treatable cause of abdominal pain. Conclusion: In conclusion, abdominal epilepsy should be suspected in children with recurrent abdominal pain.

L'acide valproïque inhibe la progression dans le cycle cellulaire chez Saccharomyces cerevisiae

L’acétylation est une modification post-traductionnelle des protéines essentielles. Elle est impliquée dans bon nombre de processus cellulaires importants comme la régulation de la structure de la chromatine et le recrutement de protéines. Deux groupes d’enzymes, soient les lysines acétyltransférases et les lysines désacétylases, régulent cette modification, autant sur les histones que sur les autres protéines. Au cours des dernières années, de petites molécules inhibitrices des désacétylases ont été découvertes. Certaines d’entre elles semblent prometteuses contre diverses maladies telles le cancer. L’acide valproïque, un inhibiteur de deux des trois classes des désacétylases, a un effet antiprolifératif chez plusieurs organismes modèles. Toutefois, les mécanismes cellulaires sous-jacents à cet effet restent encore méconnus. Ce mémoire met en lumière l’effet pH dépendant de l’acide valproïque sur différentes voies cellulaires importantes chez la levure Saccharomyces cerevisiae. Il démontre que ce composé a la capacité d’inhiber la transition entre les phases G1 et S par son action sur l’expression des cyclines de la phase G1. De plus, il inhibe l’activation de la kinase principale de la voie activée suite à un stress à la paroi cellulaire. L’acide valproïque occasionne également un arrêt dans la réplication de l’ADN sans y causer de dommage. Il s’agit là d’un effet unique qui, à notre connaissance, n’est pas observable avec d’autres agents qui inhibent la progression en phase S.

L'acide valproïque inhibe la progression dans le cycle cellulaire chez Saccharomyces cerevisiae

L’acétylation est une modification post-traductionnelle des protéines essentielles. Elle est impliquée dans bon nombre de processus cellulaires importants comme la régulation de la structure de la chromatine et le recrutement de protéines. Deux groupes d’enzymes, soient les lysines acétyltransférases et les lysines désacétylases, régulent cette modification, autant sur les histones que sur les autres protéines. Au cours des dernières années, de petites molécules inhibitrices des désacétylases ont été découvertes. Certaines d’entre elles semblent prometteuses contre diverses maladies telles le cancer. L’acide valproïque, un inhibiteur de deux des trois classes des désacétylases, a un effet antiprolifératif chez plusieurs organismes modèles. Toutefois, les mécanismes cellulaires sous-jacents à cet effet restent encore méconnus. Ce mémoire met en lumière l’effet pH dépendant de l’acide valproïque sur différentes voies cellulaires importantes chez la levure Saccharomyces cerevisiae. Il démontre que ce composé a la capacité d’inhiber la transition entre les phases G1 et S par son action sur l’expression des cyclines de la phase G1. De plus, il inhibe l’activation de la kinase principale de la voie activée suite à un stress à la paroi cellulaire. L’acide valproïque occasionne également un arrêt dans la réplication de l’ADN sans y causer de dommage. Il s’agit là d’un effet unique qui, à notre connaissance, n’est pas observable avec d’autres agents qui inhibent la progression en phase S.

No evidence for association of ataxia-telangiectasia mutated gene T2119C and C3161G amino acid substitution variants with risk of breast cancer

Background There is evidence that certain mutations in the double-strand break repair pathway ataxia-telangiectasia mutated gene act in a dominant-negative manner to increase the risk of breast cancer. There are also some reports to suggest that the amino acid substitution variants T2119C Ser707Pro and C3161G Pro1054Arg may be associated with breast cancer risk. We investigate the breast cancer risk associated with these two nonconservative amino acid substitution variants using a large Australian population-based case–control study. Methods The polymorphisms were genotyped in more than 1300 cases and 600 controls using 5' exonuclease assays. Case–control analyses and genotype distributions were compared by logistic regression. Results The 2119C variant was rare, occurring at frequencies of 1.4 and 1.3% in cases and controls, respectively (P = 0.8). There was no difference in genotype distribution between cases and controls (P = 0.8), and the TC genotype was not associated with increased risk of breast cancer (adjusted odds ratio = 1.08, 95% confidence interval = 0.59–1.97, P = 0.8). Similarly, the 3161G variant was no more common in cases than in controls (2.9% versus 2.2%, P = 0.2), there was no difference in genotype distribution between cases and controls (P = 0.1), and the CG genotype was not associated with an increased risk of breast cancer (adjusted odds ratio = 1.30, 95% confidence interval = 0.85–1.98, P = 0.2). This lack of evidence for an association persisted within groups defined by the family history of breast cancer or by age. Conclusion The 2119C and 3161G amino acid substitution variants are not associated with moderate or high risks of breast cancer in Australian women.