Influence of genetics and non-genetic factors on acenocoumarol maintenance dose requirement in Moroccan patients

What is known and Objective: Coumarin derivatives such as acenocoumarol represent the therapy of choice for the long‐term treatment and prevention of thromboembolic diseases. Many genetic, clinical and demographic factors have been shown to influence the anticoagulant dosage. Our aim was to investigate the contribution of genetic and non‐genetic factors to variability in response to acenocoumarol in Moroccan patients. Methods: Our study included 114 adult Moroccan patients, receiving long‐term acenocoumarol therapy for various indications. Tests for VKORC1 ‐1639G>A promoter polymorphism (rs9923231), CYP2C9*2 rs1799853, CYP2C9*3 rs1057910, and CYP4F2 rs2108622 alleles were undertaken using Taq Man^® Pre‐Developed Assay Reagents for allelic discrimination. The statistical analysis was performed using the SAS V9 statistical package. Results and Discussion: Genotyping showed that the allele frequencies for the SNPs studied were no different to those found in Caucasians population. A significant association was observed between the weekly maintenance dose and the VKORC1 (P = 0·0027) and CYP2C9 variant genotypes (P = 0·0082). A final multivariate regression model that included the target International Normalized Ratio, VKORC1 and CYP2C9 genotypes explained 36·2% of the overall interindividual variability in acenocoumarol dose requirement. What is new and Conclusion: Our study shows large interindividual variability in acenocoumarol maintenance dose requirement in our population. VKORC1 and CYP2C9 variants significantly affected acenocoumarol dose, in‐line with results in other populations. For the Moroccan population, the SNPs that have the largest effect on acecoumarol dose are CYP2C9 rs1799853, CYP2C9 rs1057910 and VKORC1 rs9923231.     

Akt inhibition improves irinotecan treatment and prevents cell emergence by switching the senescence response to apoptosis

Activated in response to chemotherapy, senescence is a tumor suppressive mechanism that induces a permanent loss of proliferation. However, in response to treatment, it is not really known how cells can escape senescence and how irreversible or incomplete this pathway is. We have recently described that cells that escape senescence are more transformed than non-treated parental cells, they resist anoikis and rely on Mcl-1. In this study, we further characterize this emergence in response to irinotecan, a first line treatment used in colorectal cancer. Our results indicate that Akt was activated as a feedback pathway during the early step of senescence. The inhibition of the kinase prevented cell emergence and improved treatment efficacy, both in vitro and in vivo. This improvement was correlated with senescence inhibition, p21waf1 downregulation and a concomitant activation of apoptosis due to Noxa upregulation and Mcl-1 inactivation. The inactivation of Noxa prevented apoptosis and increased the number of emergent cells. Using either RNA interference or p21waf1-deficient cells, we further confirmed that an intact p53-p21-senescence pathway favored cell emergence and that its downregulation improved treatment efficacy through apoptosis induction. Therefore, although senescence is an efficient suppressive mechanism, it also generates more aggressive cells as a consequence of apoptosis inhibition. We therefore propose that senescence-inducing therapies should be used sequentially with drugs favoring cell death such as Akt inhibitors. This should reduce cell emergence and tumor relapse through a combined induction of senescence and apoptosis.     

Exposure to mild blast forces induces neuropathological effects,neurophysiological deficits and biochemical changes

Direct or indirect exposure to an explosion can induce traumatic brain injury (TBI) of various severity levels. Primary TBI from blast exposure is commonly characterized by internal injuries, such as vascular damage, neuronal injury, and contusion, without external injuries. Current animal models of blast-induced TBI (bTBI) have helped to understand the deleterious effects of moderate to severe blast forces. However, the neurological effects of mild blast forces remain poorly characterized. Here, we investigated the effects caused by mild blast forces combining neuropathological, histological, biochemical and neurophysiological analysis. For this purpose, we employed a rodent blast TBI model with blast forces below the level that causes macroscopic neuropathological changes. We found that mild blast forces induced neuroinflammation in cerebral cortex, striatum and hippocampus. Moreover, mild blast triggered microvascular damage and axonal injury. Furthermore, mild blast caused deficits in hippocampal short-term plasticity and synaptic excitability, but no impairments in long-term potentiation. Finally, mild blast exposure induced proteolytic cleavage of spectrin and the cyclin-dependent kinase 5 activator, p35 in hippocampus. Together, these findings show that mild blast forces can cause aberrant neurological changes that critically impact neuronal functions. These results are consistent with the idea that mild blast forces may induce subclinical pathophysiological changes that may contribute to neurological and psychiatric disorders.     

Intérêt clinique de la pharmacogénétique : anticiper les toxicités et mieux prédire l’efficacité des médicaments

The narrow therapeutic index of most pharmaceutical agents and the severe consequences of undertreatment or overdosing have led to search for molecular predictive factors of toxicity and efficacy. Genetic factors involved in drug metabolism and transport partly explain inter-individual variability in drug response. Pharmacogenetics focuses on the molecular mechanisms involved in drug response. Its ultimate goal is to optimize the treatments, combining the better efficacy with the minimal risk of severe side-effects. Polymorphisms in genes encoding specific drugmetabolising enzymes may be encountered in some individuals and allow characterizing different groups in the general population as low, rapid and even ultra-rapid metabolisers. Phenotyping and genotyping tests are now available to determine or predict the metabolic status of an individual and, thus, enabling to evaluate the risk of drug failure or toxicity. Several clinical applications of pharmacogenetics (thiopurines, antivitamine K, codeine, and tramadol) have already been developed in the routine medical practice resulting in significant improvement in patient treatment. The clinical validation of an increasing number of pharmacogenetic tests as well as the development of new highly efficient technologies for genotyping should further promote pharmacogenetics in clinical practice and lead to the development of a patient-tailored drug therapy.     

A curious lobe

A case of azygos lobe is presented. An azygos lobe is an accessory lobe of the lung that may occasionally be confused with a pathological process such as a bulla, lung abscess or neoplasm. Its pathogenesis is discussed, as are the characteristic x-ray features that enable an accurate diagnosis.