Do Mice Habituate to "Gentle Handling?" A Comparison of Resting Behavior, Corticosterone Levels and Synaptic Function in Handled and Undisturbed C57BL/6J Mice.

Study Objectives: "Gentle handling" has become a method of choice for 4-6 h sleep deprivation in mice, with repeated brief handling applied before sleep deprivation to induce habituation. To verify whether mice do indeed habituate was assess how 6 days of repeated brief handling impact on resting behavior, on stress, and on the subunit content of N-methyl-D-aspartate receptors (NMDARs) at hippocampal synapases, which is altered by sleep loss. We discuss whether repeated handling biases the outcome of subsequent sleep deprivation.Design: Adult C5BL/6J mice, maintained on a 12 h-12 h light-dark cycle, were left undistrubed for 3 days, then handled during 3 min daily for 6 days in the middle of the light phase. Mice were continuously monitored for their resting time serum conticosterona levels and synaptic NMDAR subunit composition were quantified.Results: Handling caused a similar to 25% reduction of resting time throughtout all handling days, After six, but not after one day of handling, mice had elevated serum corticosterone levels. Six-day handling augmented the presence of the NR2A subunit of NMDARs at hippocampal synapses.Conclusion: Repeated handling induces behavoir and neurochemical alterations that are absent in undisturbed animals. The presistently reduced resting time and the delayed increase in conticosterone levels indicate that mice do not habituate to handling over a 1-week period. Handling-induced modifications bias effects of gentle handling-induced sleep deprivation on sleep homeostasis, stress, glutamate receptor composition and signaling. A standardization of sleep deprivation procedures involving gengle handling will be important for unequivocally specifying how acute sleep loss affects brain function.

Therapeutic PD-1 pathway blockade augments with other modalities of immunotherapy T-cell function to prevent immune decline in ovarian cancer.

The tumor microenvironment mediates induction of the immunosuppressive programmed cell death-1 (PD-1) pathway, and targeted interventions against this pathway can help restore antitumor immunity. To gain insight into these responses, we studied the interaction between PD-1 expressed on T cells and its ligands (PD-1:PD-L1, PD-1:PD-L2, and PD-L1:B7.1), expressed on other cells in the tumor microenvironment, using a syngeneic orthotopic mouse model of epithelial ovarian cancer (ID8). Exhaustion of tumor-infiltrating lymphocytes (TIL) correlated with expression of PD-1 ligands by tumor cells and tumor-derived myeloid cells, including tumor-associated macrophages (TAM), dendritic cells, and myeloid-derived suppressor cells (MDSC). When combined with GVAX or FVAX vaccination (consisting of irradiated ID8 cells expressing granulocyte macrophage colony-stimulating factor or FLT3 ligand) and costimulation by agonistic α-4-1BB or TLR 9 ligand, antibody-mediated blockade of PD-1 or PD-L1 triggered rejection of ID8 tumors in 75% of tumor-bearing mice. This therapeutic effect was associated with increased proliferation and function of tumor antigen-specific effector CD8(+) T cells, inhibition of suppressive regulatory T cells (Treg) and MDSC, upregulation of effector T-cell signaling molecules, and generation of T memory precursor cells. Overall, PD-1/PD-L1 blockade enhanced the amplitude of tumor immunity by reprogramming suppressive and stimulatory signals that yielded more powerful cancer control.

Cardiac function assessed by transesophageal echocardiography during pectus excavatum repair.

BACKGROUND: We assessed end-diastolic right ventricular (RV) dimensions and left ventricular (LV) ejection fraction by use of intraoperative transesophageal echocardiography before and after surgical correction of pectus excavatum in adults. METHODS: A prospective study was conducted including 17 patients undergoing surgical correction of pectus excavatum according to the technique of Ravitch-Shamberger between 1999 and 2004. Intraoperative transesophageal echocardiography was performed under general anesthesia before and after surgery to assess end-diastolic RV dimensions and LV ejection fraction. The end-diastolic RV diameter and area were measured in four-chamber and RV inflow-outflow view, and the RV volume was calculated from these data. The LV was assessed by transgastric short-axis view, and its ejection fraction was calculated by use of the Teichholz formula. RESULTS: The end-diastolic RV diameter, area, and volume all significantly increased after surgery (mean values +/- SD, respectively: 2.4 +/- 0.8 cm versus 3.0 +/- 0.9 cm, p < 0.001; 12.5 +/- 5.2 cm(2) versus 18.4 +/- 7.5 cm(2), p < 0.001; and 21.7 +/- 11.7 mL versus 40.8 +/- 23 mL, p < 0.001). The LV ejection fraction also significantly increased after surgery (58.4% +/- 15% versus 66.2% +/- 6%, p < 0.001). CONCLUSIONS: Surgical correction of pectus excavatum according to Ravitch-Shamberger technique results in a significant increase in end-diastolic RV dimensions and a significantly increased LV ejection fraction.

A prospective study of salivary gland function in patients undergoing radiotherapy for squamous cell carcinoma of the oropharynx

Résumé: Le traitement du cancer avancé de la tête et du cou nécessite souvent une approche multidisciplinaire associant la chirurgie, la radiothérapie et la chimiothérapie. Chacun de ces traitements présente des avantages, des limites et des inconvénients. En raison de la localisation de la tumeur primaire et/ou des métastases ganglionnaires, les glandes salivaires majeures sont fréquemment touchées par les traitements oncologiques. La salive joue un rôle déterminant dans la cavité buccale car elle lubrifie les tissus et facilite à la fois la déglutition et l'élocution. Son contenu en électrolytes et en protéines, dont certaines possèdent un effet antibactérien, protège les dents de la déminéralisation par l'acidité. Une fonction normale, liée autant à la quantité qu'à la qualité de la salive, reste indispensable pour le maintien d'une bonne santé buccale. L'objectif de cette étude prospective a été de déterminer, dans un groupe homogène de patients, l'influence d'un traitement de radiothérapie sur divers paramètres salivaires comme la sécrétion, le pH et l'effet tampon, avant, pendant et jusqu'à un an après la fin du traitement. L'étude a aussi examiné le comportement de ces paramètres salivaires après une intervention chirurgicale seule au niveau de la tête et du cou, avec ou sans exérèse d'une glande sous- maxillaire. L'étude s'est basée sur 54 patients (45 hommes et 9 femmes) atteints d'un carcinome épidermoïde avancé avec une localisation oro-pharyngée confirmée (n = 50) ou soupçonnée (n = 4), adressés et investigués dans le Centre Hospitalier Universitaire Vaudois de Lausanne, Suisse. Tous ces patients furent traités par radiothérapie seule ou en combinaison avec une chirurgie et/ou une chimiothérapie. Trente-neuf des 54 patients parvinrent à la fin de cette étude qui s'est étendue jusqu'à 12 mois au-delà de la radiothérapie. La chirurgie de la tête et cou, en particulier après ablation de la glande sous-maxillaire, a révélé un effet négatif sur la sécrétion salivaire. Elle n'influence en revanche ni le pH, ni l'effet tampon de la salive. Cependant, l'effet sur la sécrétion salivaire lié à la chirurgie est progressivement masqué par l'effet de la radiothérapie et n'est plus identifiable après 3-6 mois. Dès le début de la radiothérapie, la sécrétion salivaire chût très manifestement pour diminuer progressivement jusqu'à 1/3 de sa capacité à la fin du traitement actinique. Une année après la fin de cette radiothérapie, la dysfonction salivaire est caractérisée par une diminution moyenne de la sécrétion salivaire, de 93 % (p < 0,0001) pour la salive au repos et de 95 % (p < 0.0001) pour la salive stimulée, par rapport aux valeurs pré-thérapeutiques. Le pH salivaire ainsi que l'effet tampon furent également influencés par le traitement actinique. L'effet tampon a présenté une diminution à 67 % à une année post-traitement en comparaison de sa valeur pré-thérapeutique. Le pH de la salive stimulée présente une légère, mais significative, diminution par rapport à sa valeur antérieure à la radiothérapie. En conclusion, la chirurgie des cancers de l'oropharynx précédant une radiothérapie a une influence négative sur la sécrétion salivaire sans aggraver l'hyposialie consécutive aux radiations ionisantes. Cette étude confirme qu'un traitement oncologique comprenant une irradiation totale des glandes salivaires majeures chez des patients atteints d'un carcinome épidermoïde avancé de la région oro-pharyngée, induit une perte sévère et à long terme de la sécrétion salivaire avec une altération du pH et de l'effet tampon Abstract: Objective. We sought to investigate the impact of head and neck cancer treatment on salivary function. Study design. The study was conducted on 54 patients with advanced squamous cell carcinoma with confirmed (n =50) or suspected (n = 4) primary oropharyngeal localization who were treated with radiation alone or in combination with surgery or chemotherapy, or both. The following groups were considered in the evaluation: 1, the entire pool of patients; 2, those undergoing surgery and those not undergoing surgery before radiation; 3, those undergoing resection and those not undergoing resection of the submandibular gland. The flow rates, pH, and buffering capacity were determined before, during, and up to 12 months after the completion of radiation. Results. Head and neck surgery, particularly when submandibular gland resection was performed, had a negative impact on salivary flow rates but did not influence pH or buffering capacity. Nonetheless, the effect of surgery on salivary flow rates decreased progressively and disappeared at 3 to 6 months after radiotherapy. More than two thirds of the salivary output was lost during radiation treatment. All patients were experiencing salivary dysfunction at 1 year after completion of radiotherapy, with average decreases of 93% (P < .0001) and 95% (P < .0001) for whole resting salivary flow and whole stimulated salivary flow, respectively, compared with the preradiotherapy values. The buffering capacity decreased to 67% of its preradiotherapy value, and whole stimulated saliva became acidic. Conclusions. The result of this study confirms that cancer treatment involving full-dose radiotherapy (RTH) to all major salivary glands for locally advanced squamous cell carcinoma of the oropharynx induces severe hyposalivation with alteration of salivary pH and buffering capacity. Head and neck surgery has a negative impact on salivary flow rates, especially when the submandibular gland is removed. However, surgery before irradiation is not a factor aggravating hyposalivation when postoperative radiotherapy includes all the major salivary glands.

Subtype-specific Modulation of Acid-sensing Ion Channel (ASIC) Function by 2-Guanidine-4-methylquinazoline.

Acid-sensing ion channels (ASICs) are neuronal Na(+)-selective channels that are transiently activated by extracellular acidification. ASICs are involved in fear and anxiety, learning, neurodegeneration after ischemic stroke, and pain sensation. The small molecule 2-guanidine-4-methylquinazoline (GMQ) was recently shown to open ASIC3 at physiological pH. We have investigated the mechanisms underlying this effect and the possibility that GMQ may alter the function of other ASICs besides ASIC3. GMQ shifts the pH dependence of activation to more acidic pH in ASIC1a and ASIC1b, whereas in ASIC3 this shift goes in the opposite direction and is accompanied by a decrease in its steepness. GMQ also induces an acidic shift of the pH dependence of inactivation of ASIC1a, -1b, -2a, and -3. As a consequence, the activation and inactivation curves of ASIC3 but not other ASICs overlap in the presence of GMQ at pH 7.4, thereby creating a window current. At concentrations >1 mm, GMQ decreases maximal peak currents by reducing the unitary current amplitude. Mutation of residue Glu-79 in the palm domain of ASIC3, previously shown to be critical for channel opening by GMQ, disrupted the GMQ effects on inactivation but not activation. This suggests that this residue is involved in the consequences of GMQ binding rather than in the binding interaction itself. This study describes the mechanisms underlying the effects of a novel class of ligands that modulate the function of all ASICs as well as activate ASIC3 at physiological pH.

Right Hepatectomy in Patients over 70 Years of Age: An Analysis of Liver Function and Outcome.

BACKGROUND: As a consequence of the increase in life expectancy, hepatobiliary surgeons have to deal with an emerging aged population. We aimed to analyze the liver function and outcome after right hepatectomy (RH) in patients over 70 years of age. METHODS: From January 2006 to December 2009, we prospectively collected data of 207 consecutive elective hepatectomies. In patients who had RH, cardiac risk was assessed by a dedicated preoperative workup. Liver failure (LF) was defined by the "fifty-fifty" criteria at postoperative day 5 (POD) and morbidity by the Clavien-Dindo classification. Liver function tests (LFTs) and short-term outcome were retrospectively analyzed in patients over (elderly group, EG) and younger (young group, YG) than 70 years of age. RESULTS: Eighty-seven consecutive RH were performed during the study period. Indication for surgery included 90 % malignancy in 47 % of patients requiring preoperative chemotherapy. ASA grade > 2 (44 vs. 16 %, p = 0.027), ischemic heart disease (17 vs. 5 %, p = 0.076), and preoperative cardiac failure (26 vs. 2 %, p < 0.001) were more frequent in the EG (n = 23) than in the YG (n = 64). Both groups were similar regarding rates of normal liver parenchyma, chemotherapy and intraoperative parameters. The overall morbidity rates were comparable, but the serious complication (grades III-V) rate was relatively higher in the EG (39 vs. 25 %, p = 0.199), particularly in patients with diabetes mellitus (100 vs. 29 %, p = 0.04) and those who had additional nonhepatic surgery (67 vs. 35 %, p = 0.110) and transfusions (44 vs. 30 %, p = 0.523). The 90-day mortality rate was similar (9 % in the EG vs. 3 % in the YG, p = 0.28) and was related to heart failure in the EG. LFTs showed a similar trend from POD 1 to 8, and patients ≥70 years of age had no liver failure. CONCLUSIONS: Age ≥70 years alone is not a contraindication to RH. However, major morbidity is particularly higher in the elderly with diabetes. This high-risk group should be closely monitored in the postoperative course. Liver function is not altered in the elderly patient after RH.

Alpha1-adrenoceptors are required for normal male sexual function.

BACKGROUND AND PURPOSE: Alpha(1)-adrenoceptor antagonists are extensively used in the treatment of hypertension and lower urinary tract symptoms associated with benign prostatic hyperplasia. Among the side effects, ejaculatory dysfunction occurs more frequently with drugs that are relatively selective for alpha(1A)-adrenoceptors compared with other drugs of this class. This suggests that alpha(1A)-adrenoceptors may contribute to ejaculation. However, this has not been studied at the molecular level. EXPERIMENTAL APPROACH: The physiological contribution of each alpha(1)-adrenoceptor subtype was characterized using alpha(1)-adrenoceptor subtype-selective knockout (KO) mice (alpha(1A)-, alpha(1B)- and alpha(1D)-AR KO mice) since the subtype-specific drugs available are only moderately selective. We analysed the role of alpha(1)-adrenoceptors in the blood pressure and vascular response as well as ejaculation by determining these variables in alpha(1)-adrenoceptor subtype-selective KO mice and in mice with all their alpha(1)-adrenoceptor subtypes deleted (alpha(1)-AR triple-KO mice). KEY RESULTS: The pregnancy rate was reduced by 50% in alpha(1A)-adrenoceptor KO mice, and this reduction was dramatically enhanced in alpha(1)-adrenoceptor triple-KO mice. Contractile tension of the vas deferens in response to noradrenaline was markedly decreased in alpha(1A)-adrenoceptor KO mice, and this contraction was completely abolished in alpha(1)-adrenoceptor triple-KO mice. This attenuation of contractility was also observed in the electrically stimulated vas deferens. CONCLUSIONS AND IMPLICATIONS: These results demonstrate that alpha(1)-adrenoceptors, particularly alpha(1A)-adrenoceptors, are required for normal contractility of the vas deferens and consequent sperm ejaculation as well as having a function in fertility.

Blood pressure and cognitive function: a prospective analysis among adolescents in Seychelles

Objective: An inverse relationship between blood pressure and cognitive function has been found in adults, but limited data are available in adolescents and young adults. We prospectively examined the relation between blood pressure and cognitive function in adolescence. Methods: We examined the association between BP measured at the ages of 12-15 years in school surveys and cognitive endpoints measured in the Seychelles Child Development Study at ages 17 (n=407) and 19 (n=429) years respectively. We evaluated multiple domains of cognition based on subtests of the Cambridge Neurological Test Automated Battery (CANTAB), the Woodcock Johnson Test of Scholastic Achievement (WJTA), the Finger Tapping test (FT) and the Kaufman Brief Intelligence Test (K-BIT). We used age-, sex- and height-specific z-scores of systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP). Results: Six out of the 21 cognitive endpoints tested were associated with BP. However, none of these associations were found to hold for both males and females or for different subtests within the same neurodevelopmental domain or for both SBP and DBP. Most of these associations disappeared when analyses were adjusted for selected potential confounding factors such as socio-economic status, birth weight, gestational age, body mass index, alcohol consumption, blood glucose, and total n-3 and n-6 polyunsaturated fats. Conclusions: Our findings do not support a consistent association between BP and subsequent performance on tests assessing various cognitive domains in adolescents.

A mutation causing pseudohypoaldosteronism type 1 identifies a conserved glycine that is involved in the gating of the epithelial sodium channel.

Pseudohypoaldosteronism type 1 (PHA-1) is an inherited disease characterized by severe neonatal salt-wasting and caused by mutations in subunits of the amiloride-sensitive epithelial sodium channel (ENaC). A missense mutation (G37S) of the human ENaC beta subunit that causes loss of ENaC function and PHA-1 replaces a glycine that is conserved in the N-terminus of all members of the ENaC gene family. We now report an investigation of the mechanism of channel inactivation by this mutation. Homologous mutations, introduced into alpha, beta or gamma subunits, all significantly reduce macroscopic sodium channel currents recorded in Xenopus laevis oocytes. Quantitative determination of the number of channel molecules present at the cell surface showed no significant differences in surface expression of mutant compared with wild-type channels. Single channel conductances and ion selectivities of the mutant channels were identical to that of wild-type. These results suggest that the decrease in macroscopic Na currents is due to a decrease in channel open probability (P(o)), suggesting that mutations of a conserved glycine in the N-terminus of ENaC subunits change ENaC channel gating, which would explain the disease pathophysiology. Single channel recordings of channels containing the mutant alpha subunit (alphaG95S) directly demonstrate a striking reduction in P(o). We propose that this mutation favors a gating mode characterized by short-open and long-closed times. We suggest that determination of the gating mode of ENaC is a key regulator of channel activity.

Loss-of-Function Mutations in PTPN11 Cause Metachondromatosis, but Not Ollier Disease or Maffucci Syndrome.

Metachondromatosis (MC) is a rare, autosomal dominant, incompletely penetrant combined exostosis and enchondromatosis tumor syndrome. MC is clinically distinct from other multiple exostosis or multiple enchondromatosis syndromes and is unlinked to EXT1 and EXT2, the genes responsible for autosomal dominant multiple osteochondromas (MO). To identify a gene for MC, we performed linkage analysis with high-density SNP arrays in a single family, used a targeted array to capture exons and promoter sequences from the linked interval in 16 participants from 11 MC families, and sequenced the captured DNA using high-throughput parallel sequencing technologies. DNA capture and parallel sequencing identified heterozygous putative loss-of-function mutations in PTPN11 in 4 of the 11 families. Sanger sequence analysis of PTPN11 coding regions in a total of 17 MC families identified mutations in 10 of them (5 frameshift, 2 nonsense, and 3 splice-site mutations). Copy number analysis of sequencing reads from a second targeted capture that included the entire PTPN11 gene identified an additional family with a 15 kb deletion spanning exon 7 of PTPN11. Microdissected MC lesions from two patients with PTPN11 mutations demonstrated loss-of-heterozygosity for the wild-type allele. We next sequenced PTPN11 in DNA samples from 54 patients with the multiple enchondromatosis disorders Ollier disease or Maffucci syndrome, but found no coding sequence PTPN11 mutations. We conclude that heterozygous loss-of-function mutations in PTPN11 are a frequent cause of MC, that lesions in patients with MC appear to arise following a "second hit," that MC may be locus heterogeneous since 1 familial and 5 sporadically occurring cases lacked obvious disease-causing PTPN11 mutations, and that PTPN11 mutations are not a common cause of Ollier disease or Maffucci syndrome.

The adaptative function of melanin-based colour variants

Résumé : Les mécanismes de contrôle des couleurs mélaniques chez les vertébrés sont encore discutés parmi les biologistes de l'évolution. Une hypothèse récente affirme que les effets pléiotropies du système des mélanocortines expliquent l'association fréquente entre la coloration eumélanique noire (due à la déposition d'eumélanine) et de nombreux traits physiologiques et comportementaux. De nombreuses études suggèrent, en effet, que des niveaux plus élevés des mélanocortines induisent l'assombrissement des téguments eumélaniques et affectent d'autres traits phénotypiques simultanément. Cependant, il n'est pas encore établi si ce mécanisme de pléiotropie peut s'appliquer aux colorations dues à la déposition de phaeomélanine, une autre forme commune de mélanine. Les antagonistes des mélanocortines déclenchent le phaeomélanogenèse et bloquent l'effet des mélanocortines ou ont un effet pharmacologique opposé. Nous nous proposons donc d'évaluer l'hypothèse que les effets pléiotropes des antagonistes des mélanocortines génèrent des covariations entre la coloration phaeomélanique et des aspects de la qualité individuelle. Comme prédit par cette hypothèse, nous constatons chez la chouette effraie (Tyto alba) que les traits phénotypiques (résistance au stress oxydatif et aux parasites) corrèlent positivement au degré d'expression d'une couleur eumélanique mais négativement au degré d'expression d'une coloration phaeomélanique. Puis, nous montrons chez la chouette hulotte (Strix aluco) que les associations génétiques entre la coloration phaeomélanique et la physiologie (immunité et la régulation de l'homéostasie) confèrent des avantages aux individus de différentes couleurs dans différents environnements caractérisés par l'abondance de nourriture et le niveau d'exposition aux parasites. Ainsi, nos études soutiennent l'hypothèse que les effets pléiotropes des antagonistes des mélanocortines génèrent des covariations entre les traits mélaniques et divers aspects de la qualité individuelle. Finalement, nous montrons chez le faucon crécerelle (Falco Tinnunculus) que l'expression des ornements mélaniques est sensible à la qualité de l'environnement dans lequel les individus grandissent. Ceci suggère que les gènes codant pour les mélanocortines et leurs antagonistes pourraient induire une expression des traits mélaniques dépendante de la condition de l'individu, un pattern d'expression rarement observé pour des traits généralement sous fort contrôle génétique. Summary : The information content and control mechanisms of melanin-based colour signals in vertebrates are still debated among evolutionary biologists. A recent hypothesis contends that pleiotropic effects of the melanocortin system accounts for the frequent association between black eumelanic coloration and physiological and behavioural traits. Accordingly, empirical evidence suggests that higher levels of melanocortins concurrently promote darker eumelanic integuments and affect other phenotypic traits. However, whether this mechanism may apply to signals relying on phaeomelanin, another common form of melanin pigments, remains to be established. Melanocortin antagonists trigger phaeomelanogenesis and block the effect of melanocortins or result in the opposite pharmacological effect. Therefore, we tested the hypothesis that pleiotropic effects of melanocortin antagonists and inverse agonists account for covariations between phaeomelanin-based coloration and aspects of individual quality. As predicted, we found that phenotypic traits (resistance to oxidative stress and parasites) correlated positively with a eumelanic trait and negatively with a phaeomelanic trait in the barn owl (Tyto alba). Then, we showed in the tawny owl (Strix aluco) that genetic associations between phaeomelanin-based coloration and physiology (immunity and regulation of energy homeostasis) confer benefits to differently coloured individuals under different levels of food abundance and parasite exposure. Altogether, our studies support the hypothesis that pleiotropic effects of melanocortins antagonists can indeed account for covariations between phaeomelanin-based traits and aspects of individual quality. Eventually, we show in the Eurasian kestrel (Falco Tinnunculus) that expression of melanin-based ornaments is sensitive to the environment in which individuals grow. This suggests that genes coding for melanocortins and their antagonists can mediate the condition-dependent component of melanin-based traits.

In vivo analysis of efavirenz metabolism in individuals with impaired CYP2A6 function.

INTRODUCTION: The antiretroviral drug efavirenz (EFV) is extensively metabolized into three primary metabolites: 8-hydroxy-EFV, 7-hydroxy-EFV and N-glucuronide-EFV. There is a wide interindividual variability in EFV plasma exposure, explained to a great extent by cytochrome P450 2B6 (CYP2B6), the main isoenzyme responsible for EFV metabolism and involved in the major metabolic pathway (8-hydroxylation) and to a lesser extent in 7-hydroxylation. When CYP2B6 function is impaired, the relevance of CYP2A6, the main isoenzyme responsible for 7-hydroxylation may increase. We hypothesize that genetic variability in this gene may contribute to the particularly high, unexplained variability in EFV exposure in individuals with limited CYP2B6 function. METHODS: This study characterized CYP2A6 variation (14 alleles) in individuals (N=169) previously characterized for functional variants in CYP2B6 (18 alleles). Plasma concentrations of EFV and its primary metabolites (8-hydroxy-EFV, 7-hydroxy-EFV and N-glucuronide-EFV) were measured in different genetic backgrounds in vivo. RESULTS: The accessory metabolic pathway CYP2A6 has a critical role in limiting drug accumulation in individuals characterized as CYP2B6 slow metabolizers. CONCLUSION: Dual CYP2B6 and CYP2A6 slow metabolism occurs at significant frequency in various human populations, leading to extremely high EFV exposure.

Clinical consequences of imatinib plasma concentrations variability in hemato-oncologic patients

Background: Imatinib has revolutionized the treatment of chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GIST). Considering the large inter-individual differences in the function of the systems involved in its disposition, exposure to imatinib can be expected to vary widely among patients. This observational study aimed at describing imatinib pharmacokinetic variability and its relationship with various biological covariates, especially plasma alpha1-acid glycoprotein (AGP), and at exploring the concentration-response relationship in patients. Methods: A population pharmacokinetic model (NONMEM) including 321 plasma samples from 59 patients was built up and used to derive individual post-hoc Bayesian estimates of drug exposure (AUC; area under curve). Associations between AUC and therapeutic response or tolerability were explored by ordered logistic regression. Influence of the target genotype (i.e. KIT mutation profile) on response was also assessed in GIST patients. Results: A one-compartment model with first-order absorption appropriately described the data, with an average oral clearance of 14.3 L/h (CL) and volume of distribution of 347 L (Vd). A large inter-individual variability remained unexplained, both on CL (36%) and Vd (63%), but AGP levels proved to have a marked impact on total imatinib disposition. Moreover, both total and free AUC correlated with the occurrence and number of side effects (e.g. OR 2.9±0.6 for a 2-fold free AUC increase; p<0.001). Furthermore, in GIST patients, higher free AUC predicted a higher probability of therapeutic response (OR 1.9±0.5; p<0.05), notably in patients with tumor harboring an exon 9 mutation or wild-type KIT, known to decrease tumor sensitivity towards imatinib. Conclusion: The large pharmacokinetic variability, associated to the pharmacokinetic-pharmacodynamic relationship uncovered are arguments to further investigate the usefulness of individualizing imatinib prescription based on TDM. For this type of drug, it should ideally take into consideration either circulating AGP concentrations or free drug levels, as well as KIT genotype for GIST.

BME-based uncertainty assessment of the Chernobyl fallout

The vast territories that have been radioactively contaminated during the 1986 Chernobyl accident provide a substantial data set of radioactive monitoring data, which can be used for the verification and testing of the different spatial estimation (prediction) methods involved in risk assessment studies. Using the Chernobyl data set for such a purpose is motivated by its heterogeneous spatial structure (the data are characterized by large-scale correlations, short-scale variability, spotty features, etc.). The present work is concerned with the application of the Bayesian Maximum Entropy (BME) method to estimate the extent and the magnitude of the radioactive soil contamination by 137Cs due to the Chernobyl fallout. The powerful BME method allows rigorous incorporation of a wide variety of knowledge bases into the spatial estimation procedure leading to informative contamination maps. Exact measurements (?hard? data) are combined with secondary information on local uncertainties (treated as ?soft? data) to generate science-based uncertainty assessment of soil contamination estimates at unsampled locations. BME describes uncertainty in terms of the posterior probability distributions generated across space, whereas no assumption about the underlying distribution is made and non-linear estimators are automatically incorporated. Traditional estimation variances based on the assumption of an underlying Gaussian distribution (analogous, e.g., to the kriging variance) can be derived as a special case of the BME uncertainty analysis. The BME estimates obtained using hard and soft data are compared with the BME estimates obtained using only hard data. The comparison involves both the accuracy of the estimation maps using the exact data and the assessment of the associated uncertainty using repeated measurements. Furthermore, a comparison of the spatial estimation accuracy obtained by the two methods was carried out using a validation data set of hard data. Finally, a separate uncertainty analysis was conducted that evaluated the ability of the posterior probabilities to reproduce the distribution of the raw repeated measurements available in certain populated sites. The analysis provides an illustration of the improvement in mapping accuracy obtained by adding soft data to the existing hard data and, in general, demonstrates that the BME method performs well both in terms of estimation accuracy as well as in terms estimation error assessment, which are both useful features for the Chernobyl fallout study.