Patrick Hindlet

Long-Term Effect of Leptin on H+-Coupled Peptide Cotransporter 1 Activity and Expression in Vivo: Evidence in Leptin-Deficient Mice

The H+-coupled peptide cotransporter 1 (PepT1) mediates absorption of peptides and peptidomimetic drugs. Acute luminal leptin was reported to induce translocation of PepT1 to the enterocyte membrane in vitro and in vivo in the rat, resulting in enhanced peptide and peptidomimetic drug absorption. In this study, we analyzed chronic effects of leptin and leptin deficiency on PepT1 activity and expression in the small intestine. Wistar rats and ob/ob mice were used. Activity of PepT1 was determined by monitoring [3H]glycyl-sarcosine (Gly-Sar) transport using the jejunal loop method. The levels of PepT1 mRNA and protein were quantified by real-time quantitative reverse transcription-polymerase chain reaction and Western blot analysis, respectively. Induction of chronic hyperleptinemia in rats (1 μg/g/day for 7 days; subcutaneous continuous infusion), caused a significant 25% increase (P < 0.05 versus control) in Gly-Sar transport and uptake. This effect was associated with a significant 2-fold increase in the abundance of PepT1 protein and a 6-fold increase in the levels of PepT1 mRNA. In the leptin-deficient ob/ob mice, PepT1 activity and expression were significantly reduced, and replacement of leptin (10 μg/day for 7 days; subcutaneous continuous infusion) completely restored full PepT1 expression and activity. Moreover, we showed that a 7-day challenge of the Caco-2 cells with 0.2 nM leptin induced a significant increase in PepT1 activity and protein expression, arguing for a direct action. These data demonstrate, for the first time, an impaired activity/expression of PepT1 in leptin-deficient ob/ob mice that could be restored by leptin replacement. These findings may have relevance in modulation of dietary nitrogen supply and PepT1 substrate bioavailability in obesity.

Reduced intestinal absorption of dipeptides via PepT1 in mice with diet-induced obesity is associated with leptin receptor down-regulation.

Leptin is a major determinant of energy homeostasis, acting both centrally and in the gastrointestinal tract. We previously reported that acute leptin treatment enhances the absorption of di- and tripeptides via the proton-dependent PepT1 transporter. In this study, we investigated the long term effect of leptin on PepT1 levels and activity in Caco2 cell monolayers in vitro. We then assessed the significance of the regulation of PepT1 in vivo in a model of diet-induced obesity. We demonstrated that 1) leptin regulated PepT1 at the transcriptional level, via the MAPK pathway, and at the translational level, via ribosomal protein S6 activation, in Caco2 cells and 2) this activation was systematically followed by a time- and concentration-dependent loss of leptin action reflecting desensitization. Deciphering this desensitization, we demonstrated that leptin induced a down-regulation of its own receptor protein and mRNA expression. More importantly, we showed, in mice with diet-induced obesity, that a 4-week hypercaloric diet resulted in a 46% decrease in PepT1-specific transport, because of a 30% decrease in PepT1 protein and a 50% decrease in PepT1 mRNA levels. As shown in Caco2 cells, these changes in PepT1 were supported by a parallel 2-fold decrease in leptin receptor expression in mice. Taken together, these results indicate that during induction of obesity, leptin resistance may also occur peripherally in the gastrointestinal tract, disrupting the absorption of oligopeptides and peptidomimetic drugs.

Regulation of the Oligopeptide Transporter, PEPT-1, in DSS-Induced Rat Colitis

The effect of colitis induced with dextran sodium sulfate (DSS) in rats on the bioavailability of drugs transported by the oligopeptide transporter PepT-1 was analyzed by studying the pharmacokinetics of PepT-1 substrates: cephalexin and valacyclovir, the prodrug of antiviral acyclovir. Western blot, immunohistochemistry, and real-time PCR were used to determine the PepT-1 protein and gene expression. We observed (1) no significant modification of PepT-1 expression in the duodenum and jejunum; (2) a slight decrease in both PepT-1 mRNA (50%) and protein expression (25%) in the ileum following DSS challenge; and (3) ectopic PepT-1 immunostaining in regenerative hyperplasia segments in the distal colon from DSS-treated rats where focal inflammation is localized. However, no modification of pharmacokinetic parameters (Cmax, Tmax, AUC) of cephalexin or acyclovir was detected. In conclusion, DSS-induced rat colitis did not alter PepT-1 substrate bioavailability despite certain modifications in PepT-1 expression profile.

A systematic review of adult admissions to ICUs related to adverse drug events

Adverse drug events (ADE) may lead to hospital admission, and in some cases admission to an ICU is mandatory. We conducted a systematic review dealing with the incidence of ADE requiring ICU admission in adult patients, the reference population being all ICU admissions. Medline, Embase and Web of Science databases were screened from January 1982 to July 2014, using appropriate key words. Only original articles in English reporting the incidence of ADE requiring ICU admission in adult patients among total ICU admissions were included. Article eligibility was assessed by two independent reviewers, a third being involved in cases of disagreement. All reported characteristics (type of ICU, characteristics of patients, incidence of ADE, severity and preventability, drugs involved, causality) in the selected articles were collected for the review. The quality of studies was independently assessed by two reviewers with a specific score that we developed. A meta-analysis was conducted. Inclusion criteria were fulfilled by 11 studies out of the 4,311 identified in the initial literature search. The median (interquartile) quality score was 0.61 (0.44; 0.69). The reported incidences of ADE requiring ICU admission in adult patients ranged from 0.37 to 27.4%, with an associated mortality rate ranging from 2 to 28.1% and a mean length of stay ranging from 2.3 to 6.4 days. Preventable events accounted for 17.5 to 85.7% of the events. Costs and mechanisms at the root of ADE were investigated in only two and five studies, respectively. The forest plot examining the incidence of ADE requiring ICU admission in adult patients was associated with high heterogeneity (I2 statistic >98%), and the shape of the corresponding funnel plot was asymmetric. Heterogeneity across studies concerned many features, including studied populations, events considered, causality assessment methods, definitions of preventability and severity. Despite the heterogeneity of the reports, our review indicates that ICU admission due to ADE is a significant issue that should deserve further interest. The review led us to propose a list of items devoted to the reporting of future studies on ADE requiring ICU admissions.

Rosiglitazone and Metformin Have Opposite Effects on Intestinal Absorption of Oligopeptides via the Proton-Dependent PepT1 Transporter

The intestinal H(+)/peptide cotransporter 1 (PepT1) plays a major role in nitrogen supply to the body by mediating intestinal absorption of di- and tripeptides. Previous studies have reported that in animal models of type 2 diabetes/obesity, PepT1 activity and expression were markedly reduced. This prompted us to investigate the effects of two antidiabetic drugs, rosiglitazone and metformin, on PepT1 activity/expression in a murine diet-induced obesity model. C57BL/6J male mice were fed a high-fat diet (HFD) or a standard chow for 6 weeks and then were treated for 7 days with metformin (250 mg/kg/day) and/or rosiglitazone (8 mg/kg/day). For in vitro studies, Caco-2 enterocyte-like cells were treated for 7 days with metformin (10 mM) and/or rosiglitazone (10 μM). A 7-day rosiglitazone treatment increased PepT1 activity and prevented the 2-fold HFD-induced reduction in PepT1 transport. Metformin alone did not modify PepT1 activity but counteracted rosiglitazone-induced PepT1-mediated transport. As with the in vivo studies, rosiglitazone treatment up-regulated PepT1 transport activity with concomitant induction of S6 ribosomal protein activation in vitro. Furthermore, metformin decreased PepT1 expression (mRNA and protein) and its transport activity. The effect of metformin was linked to a reduction of phosphorylated S6 ribosomal protein (active form) and of phosphorylated 4E-BP1 (inactive form), a translation repressor. These data demonstrate that two antidiabetic drugs exert opposite effects on the PepT1 transport function probably through direct action on enterocytes. In our type 2 diabetes/obesity model, rosiglitazone, a peroxisome proliferator-activated receptor-γ agonist compensated for the HFD-induced PepT1 down-regulation, whereas metformin reversed rosiglitazone activity at the translational level.

An Observational Study of the Impact of a Computerized Physician Order Entry System on the Rate of Medication Errors in an Orthopaedic Surgery Unit.

Aim To assess the impact of the implementation of a Computerized Physician Order Entry (CPOE) associated with a pharmaceutical checking of medication orders on medication errors in the 3 stages of drug management (i.e. prescription, dispensing and administration) in an orthopaedic surgery unit. Methods A before-after observational study was conducted in the 66-bed orthopaedic surgery unit of a teaching hospital (700 beds) in Paris France. Direct disguised observation was used to detect errors in prescription, dispensing and administration of drugs, before and after the introduction of computerized prescriptions. Compliance between dispensing and administration on the one hand and the medical prescription on the other hand was studied. The frequencies and types of errors in prescribing, dispensing and administration were investigated. Results During the pre and post-CPOE period (two days for each period) 111 and 86 patients were observed, respectively, with corresponding 1,593 and 1,388 prescribed drugs. The use of electronic prescribing led to a significant 92% decrease in prescribing errors (479/1593 prescribed drugs (30.1%) vs 33/1388 (2.4%), p < 0.0001) and to a 17.5% significant decrease in administration errors (209/1222 opportunities (17.1%) vs 200/1413 (14.2%), p < 0.05). No significant difference was found in regards to dispensing errors (430/1219 opportunities (35.3%) vs 449/1407 (31.9%), p = 0.07). Conclusion The use of CPOE and a pharmacist checking medication orders in an orthopaedic surgery unit reduced the incidence of medication errors in the prescribing and administration stages. The study results suggest that CPOE is a convenient system for improving the quality and safety of drug management.

A systematic review of regulatory and educational interventions to reduce the burden associated with the prescriptions of sedative-hypnotics in adults treated for sleep disorders

Background The burden of Sedative-Hypnotics (SHs) has been known since the 1980s. Yet, their consumption remains high. A systematic review of the literature should help to assess efficient interventions to improve the appropriate use of SHs in sleep disorders. Objectives To identify and assess regulatory and educational interventions designed to improve the appropriate use of SHs for insomnia treatment. Methods We conducted a systematic review of the literature according to PRISMA guidelines. A systematic search covering the period 1980–2015 was carried out in Medline, Web of Science, Embase and PsycInfo. We included studies reporting the implementation of regulatory or educational strategies directed towards patients and/or healthcare professionals to improve the appropriate use of SHs to treat insomnia in the community, hospitals and nursing homes. Results Thirty-one studies were included: 23 assessed educational interventions (recommendations by mail/email, computer alerts, meetings, mass media campaigns, prescription profile), 8 assessed regulatory interventions (prescription rule restriction, end of reimbursement). The most recent was implemented in 2009. Restrictive prescription rules were effective to reduce the consumption of targeted SHs but led to a switch to other non-recommended SHs. Among educational interventions, only 3 studies out of 7 reported positive results of mono-faceted interventions; whereas, 13 out of the 16 multi-faceted interventions were reported as efficient: particularly, the active involvement of healthcare professionals and patients and the spread of information through mass media were successful. The risk of bias was high for 24 studies (mainly due to the design), moderate for 3 studies and weak for 4 studies. Conclusion Educational multifaceted studies are presented as the most efficient. But further better designed studies are needed to make evidence-based results more generalizable.

Monitoring of Potentially Inappropriate Prescriptions in Older Inpatients: A French Multicenter Study

To determine whether potentially inappropriate medications (PIMs) or potentially inappropriate associations (PIAs) prescribed knowingly are associated with patient monitoring.