Pendrin: linking acid base to blood pressure.

Pendrin (SLC26A4) is an anion exchanger from the SLC26 transporter family which is mutated in human patients affected by Pendred syndrome, an autosomal recessive disease characterized by sensoneurinal deafness and hypothyroidism. Pendrin is also expressed in the kidney where it mediates the exchange of internal HCO3- for external Cl- at the apical surface of renal type B and non-A non-B-intercalated cells. Studies using pendrin knockout mice have first revealed that pendrin is essential for renal base excretion. However, subsequent studies have demonstrated that pendrin also controls chloride absorption by the distal nephron and that this mechanism is critical for renal NaCl balance. Furthermore, pendrin has been shown to control vascular volume and ultimately blood pressure. This review summarizes the current knowledge about how pendrin is linking renal acid-base regulation to blood pressure control.

Exploring mitochondrial metabolism of wild-type and diabetic mice skin explants using the Seahorse technology.

BACKGROUND: Skin wound healing is a complex mechanism which requires a lot of energy, mainly provided by mitochondrial respiration. However, little is known about the mitochondrial bioenergetics of mice skin. We sought to develop a microplate-based assay to directly measure oxygen consumption in whole mice skin with the goal of identifying mitochondrial dysfunction in diabetic skin using an extracellular flux. MATERIALS AND METHODS: Different parameters were optimized to efficiently measure the oxygen consumption rate (OCR). First, the most pertinent skin side of wild-type mice was first determined. Then, concentrations of mitochondrial inhibitors were then optimized to get the best efficacy. Finally, punch sizes were modulated to get the best OCR profile. RESULTS: Dermis had the best metabolic activity side of the skin. Unlike the increased concentrations of carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP) and rotenone/antimycin A, which showed no improvement of these drugs' effects, varying the skin punch size was successful. Finally, type II diabetic (T2D) skin produced less ATP through mitochondrial metabolism and had a greater non-mitochondrial oxygen consumption than wild-type or type I diabetic (T1D) skin. CONCLUSION: Here we designed, for the first time, a reliable protocol to measure mitochondria function in whole mouse skin. Our optimized protocol was valuable in assessing alterations associated with diabetes and could be applied to future studies of pathological human skin metabolism.

ClC-K Kidney Chloride Channels: From Structure to Pathology.

The molecular basis of chloride transport varies all along the nephron depending on the tubular segments especially in the apical entry of the cell. The major chloride exit pathway during reabsorption is provided by two kidney-specific ClC chloride channels ClC-Ka and ClC-Kb (encoded by CLCNKA and CLCNKB gene, respectively) corresponding to rodent ClC-K1 and ClC-K2 (encoded by Clcnk1 and Clcnk2). These channels function as dimers and their trafficking to the plasma membrane requires the ancillary protein Barttin (encoded by BSND gene). Genetic inactivating variants of the aforementioned genes lead to renal salt-losing nephropathies with or without deafness highlighting the crucial role of ClC-Ka, ClC-Kb, and Barttin in the renal and inner ear chloride handling. The purpose of this chapter is to summarize the latest knowledge on renal chloride structure peculiarity and to provide some insight on the functional expression on the segments of the nephrons and on the related pathological effects.

Randomized comparative double-blind study assessing the difference between topically applied microbiome supporting skincare versus conventional skincare on the facial microbiome in correlation to biophysical skin parameters.

BACKGROUND: There are trillions of live bacteria, of around 1000 different species, living in human skin which are considered essential for the balance and barrier function of the skin. The gut microbiome has been a subject of extensive research and evidence shows that the gut flora is affected by preservatives and processed foods. In conventional skincare, preservatives are used, and this raises the question of how it affects the skin flora and its balance. METHODS: A randomized double-blind study on 14 healthy volunteers ages 23-45 years old were advised to use microbiome-supporting (MS) products on one cheek and benchmark (BM) products on the other cheek daily for 3 weeks. To investigate how the skin was affected, the skin microbiome was analysed using 16 S rRNA sequencing and biophysical parameters were assessed using an Antera 3D camera. Measurements were performed before and after the 3 weeks of using the products. RESULTS: The use of MS products for 3 weeks significantly increased the total number of reads mapped to unique bacterial species (p < 0.05) and the number of different unique species (p < 0.05). In addition, the use of MS products significantly reduced redness (p < 0.05) and improved skin texture (p < 0.01). The use of BM products showed no significant difference in any of the parameters except improved skin texture (p < 0.05). Additionally, the MS side showed a significantly improved diversity (p < 0.05) compared with the BM side. The four major phyla found were, similarly to previous findings by others, Actinobacteria, Firmicutes, Proteobacteria and Bacteroidetes. Some of the most prevalent species were Cutibacterium acnes, Staphylococcus epidermidis and Pseudonomas aeruginosa. CONCLUSION: The findings of this study showed significant improvements in the microbiome and biophysical parameters within 3 weeks of using MS skincare alone, while BM skincare only gave significantly improved skin roughness. Importantly, the MS side gave a significantly improved bacterial Shannon diversity (p < 0.05) compared with the BM side. Regarding the biophysical parameters, the MS skincare gave significant improvements in several parameters compared with baseline. However, they were not yet significant when compared to using BM skincare and therefore a larger study population will be needed. Importantly, this is the first study to investigate how preservatives affect the facial microbiome in vivo and has raised a need for further investigation. These results together with further studies can lead to innovations within the cosmetic industry that promote healthier skin.

CONTEXTE: Il existe des milliers de milliards de bactéries vivantes, d'environ 1 000 espèces différentes, vivant dans la peau humaine, qui sont considérées comme essentielles pour l'équilibre et la fonction barrière de la peau. Le microbiome intestinal a fait l'objet de recherches approfondies, et des preuves montrent que la flore intestinale est affectée par les conservateurs et les aliments transformés. Dans les soins de la peau traditionnels, des conservateurs sont utilisés, ce qui soulève la question de leur effet sur la flore cutanée et son équilibre. MÉTHODES: Dans une étude randomisée en double aveugle, il a été conseillé à 14 volontaires en bonne santé âgés de 23 à 45 ans d'utiliser quotidiennement des produits nourrissant le microbiome (NM) sur une joue et des produits de référence sur l'autre joue pendant 3 semaines. Pour étudier l'effet sur la peau, le microbiome cutané a été analysé à l'aide d'un séquençage ARNr 16S, et les paramètres biophysiques ont été évalués à l'aide d'une caméra 3D Antera. Les mesures ont été réalisées avant et après les 3 semaines d'utilisation des produits. RÉSULTATS: L'utilisation de produits NM pendant 3 semaines a significativement augmenté le nombre total de résultats cartographiés pour des espèces bactériennes uniques (p < 0,05) et le nombre d'espèces uniques différentes (p < 0,05). En outre, l'utilisation de produits NM a significativement réduit la rougeur (p < 0,05) et amélioré la texture de la peau (p < 0,01). L'utilisation de produits de référence n'a montré aucune différence significative dans aucun des paramètres, à l'exception de l'amélioration de la texture de la peau (p < 0,05). En outre, les produits NM ont montré une diversité significativement améliorée (p < 0,05) par rapport aux produits de référence. Les quatre principaux embranchements identifiés étaient, de manière similaire aux résultats précédents d'autres études, les actinobactéries, les bacillota, les protéobactéries et les bactéroïdètes. Certaines des espèces les plus prévalentes étaient Cutibacterium acnes, Staphylococcus epidermidis et Pseudomonas aeruginosa. CONCLUSION: Les résultats de cette étude ont montré des améliorations significatives du microbiome et des paramètres biophysiques dans les 3 semaines suivant l'utilisation de soins de la peau NM seuls, tandis que les soins de la peau de référence n'ont permis qu'une amélioration significative de la rugosité de la peau. Il est important de noter que les produits NM ont permis une amélioration significative de la diversité bactérienne de Shannon (p < 0,05) par rapport aux produits de référence. En ce qui concerne les paramètres biophysiques, les soins de la peau NM ont apporté des améliorations significatives de plusieurs paramètres par rapport à l'entrée dans l'étude. Cependant, ils n'étaient pas encore significatifs par rapport à l'utilisation de soins de la peau de référence et, par conséquent, une étude avec une population plus importante sera nécessaire. Il est important de noter qu'il s'agit de la première étude examinant l'effet des conservateurs sur le microbiome facial in vivo et qu'elle a soulevé la nécessité d'une étude plus approfondie. Ces résultats, ainsi que des études complémentaires, peuvent conduire à des innovations au sein de l'industrie cosmétique qui favorisent une peau en meilleure santé.

Exome sequencing allows detection of relevant pharmacogenetic variants in epileptic patients.

Beyond the identification of causal genetic variants in the diagnosis of Mendelian disorders, exome sequencing can detect numerous variants with potential relevance for clinical care. Clinical interventions can thus be conducted to improve future health outcomes for patients and their at-risk relatives, such as predicting late-onset genetic disorders accessible to prevention, treatment or identifying differential drug efficacy and safety. To evaluate the interest of such pharmacogenetic information, we designed an "in house" pipeline to determine the status of 122 PharmGKB (Pharmacogenomics Knowledgebase) variant-drug combinations in 31 genes. This pipeline was applied to a cohort of 90 epileptic patients who had previously an exome sequencing (ES) analysis, to determine the frequency of pharmacogenetic variants. We performed a retrospective analysis of drug plasma concentrations and treatment efficacy in patients bearing at least one relevant PharmGKB variant. For PharmGKB level 1A variants, CYP2C9 status for phenytoin prescription was the only relevant information. Nineteen patients were treated with phenytoin, among phenytoin-treated patients, none were poor metabolizers and four were intermediate metabolizers. While being treated with a standard protocol (10-23 mg/kg/30 min loading dose followed by 5 mg/kg/8 h maintenance dose), all identified intermediate metabolizers had toxic plasma concentrations (20 mg/L). In epileptic patients, pangenomic sequencing can provide information about common pharmacogenetic variants likely to be useful to guide therapeutic drug monitoring, and in the case of phenytoin, to prevent clinical toxicity caused by high plasma levels.

The role of spatial competitive interactions between trees in shaping forest patterns.

General patterns that are observed in forests irrespective of their ecological biome or species composition are indicators of general biological processes that drive forest dynamics. Modelling can be used to infer these processes by identifying the minimum set of rules that generate the observed patterns. The regular spatial pattern of the largest trees, the decreasing skewness of the tree diameter distribution in young developing stands, and the size bimodality that may result from the tail of dominated trees are three general patterns observed in natural forests. Using a simple individual-based space-dependent growth model based on asymmetric competition between trees and space-independent approximations of this model, the objectives were (1) to identify a single mechanism that may explain these three patterns, and (2) to clarify the role of space in the emergence of these patterns. The space-dependent model was able to qualitatively generate the three patterns. Through cascading spatial interactions, competition resulted in the establishment of a spatially structured competitive hierarchy among trees. A second-order approximation of the space-dependent model was derived by structuring the population of trees according to diameter and competitive status. This second-order approximation succeeded in predicting left-skewed diameter distributions but did not predict diameter bimodality. Asymmetric competition thus seems to be an important driver of tree growth and the cause rather than the consequence of bimodality. The second-order approximation of the space-dependent model may be useful to generalize the stationary diameter distributions developed in the demographic equilibrium theory.

Personalized Therapy for Mycophenolate: Consensus Report by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology.

ABSTRACT: When mycophenolic acid (MPA) was originally marketed for immunosuppressive therapy, fixed doses were recommended by the manufacturer. Awareness of the potential for a more personalized dosing has led to development of methods to estimate MPA area under the curve based on the measurement of drug concentrations in only a few samples. This approach is feasible in the clinical routine and has proven successful in terms of correlation with outcome. However, the search for superior correlates has continued, and numerous studies in search of biomarkers that could better predict the perfect dosage for the individual patient have been published. As it was considered timely for an updated and comprehensive presentation of consensus on the status for personalized treatment with MPA, this report was prepared following an initiative from members of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT). Topics included are the criteria for analytics, methods to estimate exposure including pharmacometrics, the potential influence of pharmacogenetics, development of biomarkers, and the practical aspects of implementation of target concentration intervention. For selected topics with sufficient evidence, such as the application of limited sampling strategies for MPA area under the curve, graded recommendations on target ranges are presented. To provide a comprehensive review, this report also includes updates on the status of potential biomarkers including those which may be promising but with a low level of evidence. In view of the fact that there are very few new immunosuppressive drugs under development for the transplant field, it is likely that MPA will continue to be prescribed on a large scale in the upcoming years. Discontinuation of therapy due to adverse effects is relatively common, increasing the risk for late rejections, which may contribute to graft loss. Therefore, the continued search for innovative methods to better personalize MPA dosage is warranted.

MRP4 is responsible for the efflux transport of mycophenolic acid ß-d glucuronide (MPAG) from hepatocytes to blood.

Mycophenolic acid (MPA) has become a cornerstone of immunosuppressive therapy, in particular for transplant patients. In the gastrointestinal tract, the liver and the kidney, MPA is mainly metabolized into phenyl-ß-d glucuronide (MPAG). Knowledge about the interactions between MPA/MPAG and membrane transporters is still fragmented. The aim of the present study was to explore these interactions with the basolateral hepatic MRP4 transporter. The inhibition of the MRP4-driven transport by various drugs which can be concomitantly prescribed was also evaluated. In vitro experiments using vesicles overexpressing MRP4 showed an ATP-dependent transport of MPAG driven by MRP4 (Michaelis-Menten constant of 233.9 ± 32.8 µM). MPA was not effluxed by MRP4. MRP4-mediated transport of MPAG was inhibited (from -43% to -84%) by ibuprofen, cefazolin, cefotaxime and micafungin. An in silico approach based on molecular docking and molecular dynamics simulations rationalized the mode of binding of MPAG to MRP4. The presence of the glucuronide moiety in MPAG was highlighted as key, being prone to make electrostatic and H-bond interactions with specific residues of the MRP4 protein chamber. This explains why MPAG is a substrate of MRP4 whereas MPA is not.

Effect of genetic polymorphisms in CYP3A4, CYP3A5, and m-TOR on everolimus blood exposure and clinical outcomes in cancer patients.

Genetic variations in CYP3A4, CYP3A5, and m-TOR could contribute to interpatient variability regarding m-TOR inhibitors pharmacokinetics or cellular effects. The purpose of this study was to evaluate the influence of selected candidate variations in these genes on everolimus pharmacokinetics, efficacy, and toxicity in cancer patients. Thirty-four patients receiving everolimus for breast (n = 22) or renal (n = 10) cancers, or neuroendocrine tumors of pancreatic origin (n = 2) were included in the study. Six variants in genes related to everolimus pharmacokinetics (CYP3A4*22 and CYP3A5*3) or pharmacodynamics (m-TOR rs2295079, rs2295080, rs2024627 and rs1057079) were genotyped. Associations with trough concentrations (C0), dose reductions, or treatment interruptions due to toxicity and progression-free survival were investigated using generalized estimating equations and Cox models. CYP3A5 nonexpressers had significantly higher C0 as compared with expressers (ßGG vs AG = + 6.32 ± 2.22 ng/mL, p = 0.004). m-TOR rs2024627 was significantly associated with an increased risk of cancer progression studied alone or as part of an haplotype (T vs C: HR = 2.60, 95% CI [1.16-5.80], p = 0.020; CTCG vs other haplotypes HR = 2.29, 95% CI [1.06-4.95], p = 0.035, respectively). This study showed that CYP3A5 expression impacts everolimus pharmacokinetics in cancer patients and identified a genetic variation in m-TOR associated with the risk of cancer progression.

Role of good oral hygiene on clinical evolution of rheumatoid arthritis: a randomized study nested in the ESPOIR cohort.

OBJECTIVE: There is a relationship between RA and periodontal disease. We aimed to investigate if a good oral hygiene could improve activity of RA. METHODS: The patients with RA according to ACR/EULAR 2010 criteria and included in the French early arthritis ESPOIR cohort were included in a randomized nested study into: (i) intervention group: general recommendations of good oral hygiene including teeth brushing, daily antiseptic mouthwash and twice a year scaling; and (ii) control group: no intervention. The primary end point was the delta DAS28-ESR. RESULTS: Four hundred and seventy-two patients were randomized (238 in intervention and 234 in control). 92/238 from the intervention group accepted the procedure and 81 had a first visit to the dentist. 56% of patients had periodontal disease at baseline. Duration of RA was 9.0±0.7 years. Baseline DAS28-ESR was 2.7±1.3. After a median duration of 24 months, delta DAS28-ESR was -0.17±1.29 and -0.09±1.28 in intervention and control groups, respectively (mean difference (complier average causal effect): -0.37 (95% CI -1.12, 0.37), P = 0.33). In the intervention group, there was a significant decrease of the bacteria involved in the red complex: Porphyromonas gingivalis (P = 0.002), Tannerella forsythia (P = 0.002) and Treponema denticola (P = 0.019). The patients with baseline periodontal disease and those who became negative for one red complex bacterium had a slightly more important decrease of DAS28-ESR. CONCLUSION: Oral hygiene instruction together with regular scaling and polishing of the teeth significantly decreased the load of periodontal pathogens but did not decrease RA activity. This intervention should be tested in patients with earlier RA and more active disease. TRIAL REGISTRATION: ClinicalTrials.gov, http://clinicaltrials.gov, NCT01831648.

Phenotyping of Uracil and 5-Fluorouracil Metabolism Using LC-MS/MS for Prevention of Toxicity and Dose Adjustment of Fluoropyrimidines.

BACKGROUND: Plasma concentrations of fluoropyrimidine exhibit a wide interindividual variability that depends mainly on the activity of dihydropyrimidine dehydrogenase, its major catabolic enzyme. Patients with low dihydropyrimidine dehydrogenase activity are at an increased risk of overexposure and often severe, sometimes lethal, toxicity. This study aimed to develop a quick and easy bioanalytical method for the simultaneous determination of endogenous uracil (U), exogenous 5-fluorouracil (5-FU), and their respective 5,6-dihydro-metabolite in human plasma using Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). METHODS: After protein precipitation, the compounds were purified using liquid-liquid extraction. Chromatographic separation was conducted using a Cortecs T3 column and binary gradient elution. Detection and quantification were performed in the positive electrospray ionization and selected the reaction monitoring mode after 2 transitions per analyte and 1 per internal standard. The data obtained with this technique were retrospectively gathered for uracil metabolism phenotyping before fluoropyrimidine treatment (as enforced by national regulations) in a large group of 526 patients. RESULTS: The analytical response was linear (r > 0.99 for all compounds), and it yielded a lower limit of quantification of 2 ng·mL for U and UH2 as well as 4 ng·mL for 5-FU and 5,6-dihydro-5-FUH2. The median uracil concentration in 526 patients was 10.6 mcg/L, with extreme values of 3.9 and 81.6 mcg/L; 78 patients (15%) had uracil concentration ≥16 mcg/L, that is, above the threshold of decreased enzyme activity and initial dose reduction.

[COVID-19, management, therapeutic and vaccine approaches]. / Covid-19, prise en charge, pistes thérapeutiques et vaccinales.

While at the beginning of 2020, the COVID-19 epidemic was spreading at tremendous speed, many scientific teams set to work around the world. The management of severe acute respiratory syndrome coronavirus 2 infections is based on experimental non-specific (symptomatic) or specific (curative) treatments. The vaccine will be the key to long-term immunization.

Self-poisoning with 60 tablets of Apixaban, a pharmacokinetics case report.

A 67-year-old man was admitted to the emergency department about 5 h after deliberate self-poisoning with 300 mg of Apixaban. The clinical examination did not show any organ dysfunctions or haemorrhagic signs, and the patient's life was not in danger. The first analysis, upon admission, showed a concentration of 2655 µg l-1 of Apixaban. The Cmax was observed 17 h after the intake (3654 µg l-1 ), about four times the classical Tmax value (median [range]: 4 h [2-4]). The Apixaban was then eliminated following a first order elimination with a calculated half-life of 10.8 h. The anti-Xa activity seems to be linearly related to concentration up to 4000 µg l-1 . This report suggests that the use of activated charcoal should be effective up to 17 h after a massive intake.

Pharmacogenetics Biomarkers Predictive of Drug Pharmacodynamics as an Additional Tool to Therapeutic Drug Monitoring.

Conventional therapeutic drug monitoring refers to the individualization of drug dosage by maintaining plasma or blood drug concentrations within a targeted therapeutic range. Accordingly, an individualized dose is proposed to the clinician according to the drug plasma or blood concentration using an a posteriori approach. Pharmacogenetics (PGx) has recently emerged as an additional tool to refine dose selection or, more interestingly to select, a priori, the first dose to administer. To date, the vast majority of genes explored in the context of PGx are those coding for metabolizing enzymes or membrane drug transporters, which mainly influence drug pharmacokinetics parameters. Indeed, among the 94 PGx-based drug dosing guidelines currently published by the Clinical Pharmacogenetics Implementation Consortium and the Dutch Pharmacogenetics Working Group on PharmGKB web site, 81 (86%) are associated with the genotype determination of either a metabolizing enzyme or a membrane drug transporter, whereas only 13 (14%) are associated with the genotype determination of a pharmacodynamics (PD)-associated gene. In this article, we describe selected PGx biomarkers that predict or could predict PD (both in terms of efficacy and toxicity). First, the most relevant clinical applications already subject to validated international guidelines (Clinical Pharmacogenetics Implementation Consortium and Dutch Pharmacogenetics Working Group), and ready to be implemented in routine clinical settings, are discussed to illustrate the clinical potential of PD-associated PGx biomarkers (G6PD, HLA-B*57:01, HLA-B*15:02, and VKORC1). Then, to illustrate not only the research potential of such biomarkers but also the complexity of PGx-PD relationships, the case of immunosuppressive drugs (for which conventional therapeutic drug monitoring is widely accepted) is extensively described with the potential to include some of these PGx biomarkers in future PGx dosing guidelines.

Therapeutic Drug Monitoring of Tacrolimus-Personalized Therapy: Second Consensus Report.

Ten years ago, a consensus report on the optimization of tacrolimus was published in this journal. In 2017, the Immunosuppressive Drugs Scientific Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicity (IATDMCT) decided to issue an updated consensus report considering the most relevant advances in tacrolimus pharmacokinetics (PK), pharmacogenetics (PG), pharmacodynamics, and immunologic biomarkers, with the aim to provide analytical and drug-exposure recommendations to assist TDM professionals and clinicians to individualize tacrolimus TDM and treatment. The consensus is based on in-depth literature searches regarding each topic that is addressed in this document. Thirty-seven international experts in the field of TDM of tacrolimus as well as its PG and biomarkers contributed to the drafting of sections most relevant for their expertise. Whenever applicable, the quality of evidence and the strength of recommendations were graded according to a published grading guide. After iterated editing, the final version of the complete document was approved by all authors. For each category of solid organ and stem cell transplantation, the current state of PK monitoring is discussed and the specific targets of tacrolimus trough concentrations (predose sample C0) are presented for subgroups of patients along with the grading of these recommendations. In addition, tacrolimus area under the concentration-time curve determination is proposed as the best TDM option early after transplantation, at the time of immunosuppression minimization, for special populations, and specific clinical situations. For indications other than transplantation, the potentially effective tacrolimus concentrations in systemic treatment are discussed without formal grading. The importance of consistency, calibration, proficiency testing, and the requirement for standardization and need for traceability and reference materials is highlighted. The status for alternative approaches for tacrolimus TDM is presented including dried blood spots, volumetric absorptive microsampling, and the development of intracellular measurements of tacrolimus. The association between CYP3A5 genotype and tacrolimus dose requirement is consistent (Grading A I). So far, pharmacodynamic and immunologic biomarkers have not entered routine monitoring, but determination of residual nuclear factor of activated T cells-regulated gene expression supports the identification of renal transplant recipients at risk of rejection, infections, and malignancy (B II). In addition, monitoring intracellular T-cell IFN-g production can help to identify kidney and liver transplant recipients at high risk of acute rejection (B II) and select good candidates for immunosuppression minimization (B II). Although cell-free DNA seems a promising biomarker of acute donor injury and to assess the minimally effective C0 of tacrolimus, multicenter prospective interventional studies are required to better evaluate its clinical utility in solid organ transplantation. Population PK models including CYP3A5 and CYP3A4 genotypes will be considered to guide initial tacrolimus dosing. Future studies should investigate the clinical benefit of time-to-event models to better evaluate biomarkers as predictive of personal response, the risk of rejection, and graft outcome. The Expert Committee concludes that considerable advances in the different fields of tacrolimus monitoring have been achieved during this last decade. Continued efforts should focus on the opportunities to implement in clinical routine the combination of new standardized PK approaches with PG, and valid biomarkers to further personalize tacrolimus therapy and to improve long-term outcomes for treated patients.

Contributions of a blended learning based on peer evaluation for teaching drug-drug interactions to undergraduate pharmacy students.

BACKGROUND: Numerous studies have pointed out the need for better training of healthcare professionals in drug-drug interactions management in order to minimize adverse drugs reactions impacts on patients. The aim of this study was to evaluate the benefits of a blended learning strategy based on peer evaluation (PE) for teaching drug-drug interactions to undergraduate pharmacy students. METHODS: Third-year pharmacy students (n = 72) from the University of Limoges were involved in a hybrid teaching using the Moodle platform (2.9 version). After the theoretical lectures, an online activity was proposed to students. Each student submitted a report addressing a clinical case for peer evaluation. Students evaluated the pedagogical approach using an online survey. Quantitative benefits were assessed from students randomly assigned into two groups: PE in pharmacodynamics items (PE-PD) or PE in pharmacokinetics items (PE-PK). During this activity, three marks were given: one from peers for their evaluation work and two from teachers for oral group presentation of the clinical cases and for the final written examination. Statistics were performed using two-tailed unpaired t-test and significance was set for p < 0.05. RESULTS: Only a few students (n = 14, 20.6%) were aware of the peer evaluation principle and even less, only one student (n = 1, 1.5%), had already encountered it. Students considered that they benefited from this evaluation (n = 65, 95.6%); from their work being reviewed (n = 62, 91.2%) and that they participated in improving their classmates understanding (n = 59, 86.8%). Peers' allocated marks were similar in the two PE groups (PE-PD = 17.4 ± 1.4; PE-PK = 17.3 ± 1.4). Teachers' marks for oral presentation were significantly lower for pharmacodynamics than for pharmacokinetics items (PE-PD = 15.2 ± 1.2; PE-PK = 16.1 ± 2.1; p < 0.05). The final examination marks were equivalent in both groups (PE-PD = 11.0 ± 2.1; PE-PK = 11.2 ± 1.9). CONCLUSIONS: Besides the fact that a major short-term quantitative improvement was not detected, our teaching approach was qualified as being a positive and stimulating learning tool by students.

A donor and recipient candidate gene association study of allograft loss in renal transplant recipients receiving a tacrolimus-based regimen.

This work investigated, in two large cohorts of French renal transplants treated with tacrolimus, the influence of donor and recipient ABCB1, CYP3A4, and CYP3A5 genotypes on the risk of allograft loss. A discovery and a replication population of 330 and 369 adult renal transplant patients, each from a different transplantation center and all receiving a tacrolimus-based immunosuppressive regimen, were retrospectively genotyped. The influence of genetic factors and other known risk factors on allograft loss was investigated using multivariate Cox proportional hazard analyses. The existence of previous transplantations (per unit HR = 1.89 [1.10-3.26] P = .0216) and the donor ABCB1 c.1199GA/AA genotype (GA/AAvs GG: HR = 3.22 [1.14-9.09], P = .0288) were associated with an increased risk of allograft loss in the discovery cohort and with graft loss due to humoral rejection in the replication cohort (per unit HR = 2.26 [1.34-3.81], P = .00229; GA/AAvs GG HR = 3.42 [1.28-9.16], P = .0142). Genotyping the donor for the ABCB1 c.1199 G>A (exon 11, rs2229109) allele may be of interest before prescribing tacrolimus to the recipient, although this polymorphism is rather rare and its effect may be limited to certain mechanisms of graft loss.

Cutaneous and renal vasodilatory response to local pressure application: A comparative study in mice.

BACKGROUND AND AIM: We have reported a novel relationship involving mechanical stimulation and vasodilation in rodent and human skin, referred to as pressure-induced vasodilation (PIV). It is unknown whether this mechanism exists in kidney and reflects the microcirculation in deep organs. Therefore, we compared the skin and kidney PIV to determine whether their changes were similar. METHODS: In anesthetized mice fed a normal salt-diet, laser Doppler flux (LDF) signals were measured when an increase in local pressure was applied to the surface of the head skin with the rate of 2.2Pa/s (1mmHg/min) and to the left kidney with a rate of 4.4Pa/s (2mmHg/min). The mechanism underlying renal PIV was also investigated. The skin and kidney PIV were also compared during salt load (4% NaCl diet). RESULTS: The kidney had higher baseline LDF and vascular conductance compared to those of the skin. Pressure application increased the LDF in the kidney as well as in the skin with a comparable maximal magnitude (about 25% from baseline value), despite different kinetics of PIV evolution. As we previously reported in the skin, the kidney PIV response was mediated by the activation of transient receptor potential vanilloid type 1 channels, the release of calcitonin gene-related peptide, and the participation of prostaglandins and nitric oxide. In the absence of hypertension, high salt intake abolished the cutaneous PIV response and markedly impaired the renal one. CONCLUSION: PIV response in the mouse kidney results from a neuro-vascular interaction. Despite some differences between the skin and the kidney PIV, the similarities in their response and signaling mechanisms suggest that the cutaneous microcirculation could reflect, in part, the microcirculation of the renal cortex.

The ClC-K2 Chloride Channel Is Critical for Salt Handling in the Distal Nephron.

Chloride transport by the renal tubule is critical for blood pressure (BP), acid-base, and potassium homeostasis. Chloride uptake from the urinary fluid is mediated by various apical transporters, whereas basolateral chloride exit is thought to be mediated by ClC-Ka/K1 and ClC-Kb/K2, two chloride channels from the ClC family, or by KCl cotransporters from the SLC12 gene family. Nevertheless, the localization and role of ClC-K channels is not fully resolved. Because inactivating mutations in ClC-Kb/K2 cause Bartter syndrome, a disease that mimics the effects of the loop diuretic furosemide, ClC-Kb/K2 is assumed to have a critical role in salt handling by the thick ascending limb. To dissect the role of this channel in detail, we generated a mouse model with a targeted disruption of the murine ortholog ClC-K2. Mutant mice developed a Bartter syndrome phenotype, characterized by renal salt loss, marked hypokalemia, and metabolic alkalosis. Patch-clamp analysis of tubules isolated from knockout (KO) mice suggested that ClC-K2 is the main basolateral chloride channel in the thick ascending limb and in the aldosterone-sensitive distal nephron. Accordingly, ClC-K2 KO mice did not exhibit the natriuretic response to furosemide and exhibited a severely blunted response to thiazide. We conclude that ClC-Kb/K2 is critical for salt absorption not only by the thick ascending limb, but also by the distal convoluted tubule.

Intercalated Cell Depletion and Vacuolar H+-ATPase Mistargeting in an Ae1 R607H Knockin Model.

Distal nephron acid secretion is mediated by highly specialized type A intercalated cells (A-ICs), which contain vacuolar H+-ATPase (V-type ATPase)-rich vesicles that fuse with the apical plasma membrane on demand. Intracellular bicarbonate generated by luminal H+ secretion is removed by the basolateral anion-exchanger AE1. Chronically reduced renal acid excretion in distal renal tubular acidosis (dRTA) may lead to nephrocalcinosis and renal failure. Studies in MDCK monolayers led to the proposal of a dominant-negative trafficking mechanism to explain AE1-associated dominant dRTA. To test this hypothesis in vivo, we generated an Ae1 R607H knockin mouse, which corresponds to the most common dominant dRTA mutation in human AE1, R589H. Compared with wild-type mice, heterozygous and homozygous R607H knockin mice displayed incomplete dRTA characterized by compensatory upregulation of the Na+/HCO3- cotransporter NBCn1. Red blood cell Ae1-mediated anion-exchange activity and surface polypeptide expression did not change. Mutant mice expressed far less Ae1 in A-ICs, but basolateral targeting of the mutant protein was preserved. Notably, mutant mice also exhibited reduced expression of V-type ATPase and compromised targeting of this proton pump to the plasma membrane upon acid challenge. Accumulation of p62- and ubiquitin-positive material in A-ICs of knockin mice suggested a defect in the degradative pathway, which may explain the observed loss of A-ICs. R607H knockin did not affect type B intercalated cells. We propose that reduced basolateral anion-exchange activity in A-ICs inhibits trafficking and regulation of V-type ATPase, compromising luminal H+ secretion and possibly lysosomal acidification.