A practical guide for probiotics applied to the case of antibiotic-associated diarrhea in The Netherlands

Abstract Background Antibiotic-associated diarrhea (AAD) is a side-effect frequently associated with the use of broad spectrum antibiotics. Although a number of clinical studies show that co-administration of specific probiotics reduces the risk for AAD, there is still unclarity among healthcare professionals on the recommendation of probiotic products. This paper aims at a practical guide to inform healthcare professionals, patients and consumers about the exact product characteristics of available probiotics with a proven efficacy to prevent AAD. Methods The workflow in this paper includes three consecutive steps: 1) systematic review of relevant clinical studies for effective probiotics by a meta-analysis, 2) compilation of a list of available probiotic products, and 3) recommendation of probiotic products that match effective formulations. Our systematic review on the efficacy of probiotics for the prevention of AAD included only studies with randomized, double blind placebo-controlled trials, a clear definition of antibiotic associated diarrhea, and a probiotic administration regime for at least the duration of the antibiotic therapy. Results Using our inclusion criteria, we selected 32 out of 128 identified trials and pooled the results of these studies for each specific dairy product and food supplement. The results indicate a total of seven single or multiple-strain formulations favoring the probiotic treatment group, with the strain Lactobacillus rhamnosus GG being the most effective [relative risk ratio of probiotic versus placebo 0.30 (95% CI 0.16–0.5)]. We selected products for recommendation from a compiled list of all probiotic dairy products and food supplements available in The Netherlands and categorized them into groups of products showing effects against the incidence of AAD in at least one, two or three independent clinical studies. We excluded all products which did not unambiguously declare on the label the specific probiotic strain(s) and the number of colony forming units. Conclusion Here we present a practical guide that informs healthcare professionals and patients on the availability of probiotic products with a proven efficacy for the prevention of AAD

Regional expression levels of drug transporters and metabolizing enzymes along the pig and human intestinal tract and comparison with Caco-2 cells

Intestinal transporter proteins and metabolizing enzymes play a crucial role in the oral absorption of a wide variety of drugs. The aim of the current study was to better characterize available intestinal in vitro models by comparing expression levels of these proteins and enzymes between porcine intestine, human intestine and Caco-2 cells. We therefore determined the absolute protein expression of 19 drug transporters and the mRNA expression of 12 metabolic enzymes along the pig intestinal tract (duodenum, jejunum, ileum; N=4), in human intestine (jejunum; N=9) and Caco-2 cells. Expression of the included transporters and enzymes was in general well comparable between porcine and human intestinal tissue, though BCRP, MCT5, MDR1, MRP1, MRP3 (~2-fold) and OATP4A1 (~6-fold) was higher expressed in pig compared to human jejunum. Alternatively, expression level of relevant transporter proteins (GLUT1, OATP4A1, MRP2, MRP1 and OATP2B1) was significantly higher (3- to 130-fold) in Caco-2 cells compared to human jejunum. Moreover, all examined CYPs showed at least a five-fold lower gene expression in Caco-2 cells compared to human jejunum, with the smallest differences for CYP1A1 and CYP3A5 and the largest difference for CYP3A4 (871-fold higher expression in human jejunum compared to Caco-2 cells). In conclusion, a comprehensive overview is provided of the expression levels of clinically relevant transporter proteins and metabolic enzymes in porcine and human intestinal tissue, and Caco-2 cells, which may assist in deciding upon the most suitable model to further improve our understanding of processes that determine intestinal absorption of compounds

Regional expression levels of drug transporters and metabolizing enzymes along the pig and human intestinal tract and comparison with Caco-2 cells

Intestinal transporter proteins and metabolizing enzymes play a crucial role in the oral absorption of a wide variety of drugs. The aim of the current study was to better characterize available intestinal in vitro models by comparing expression levels of these proteins and enzymes between porcine intestine, human intestine and Caco-2 cells. We therefore determined the absolute protein expression of 19 drug transporters and the mRNA expression of 12 metabolic enzymes along the pig intestinal tract (duodenum, jejunum, ileum; N=4), in human intestine (jejunum; N=9) and Caco-2 cells. Expression of the included transporters and enzymes was in general well comparable between porcine and human intestinal tissue, though BCRP, MCT5, MDR1, MRP1, MRP3 (~2-fold) and OATP4A1 (~6-fold) was higher expressed in pig compared to human jejunum. Alternatively, expression level of relevant transporter proteins (GLUT1, OATP4A1, MRP2, MRP1 and OATP2B1) was significantly higher (3- to 130-fold) in Caco-2 cells compared to human jejunum. Moreover, all examined CYPs showed at least a five-fold lower gene expression in Caco-2 cells compared to human jejunum, with the smallest differences for CYP1A1 and CYP3A5 and the largest difference for CYP3A4 (871-fold higher expression in human jejunum compared to Caco-2 cells). In conclusion, a comprehensive overview is provided of the expression levels of clinically relevant transporter proteins and metabolic enzymes in porcine and human intestinal tissue, and Caco-2 cells, which may assist in deciding upon the most suitable model to further improve our understanding of processes that determine intestinal absorption of compounds

Prediction of the Carcinogenic Potential of Human Pharmaceuticals Using Repeated Dose Toxicity Data and Their Pharmacological Properties

In an exercise designed to reduce animal use, we analyzed the results of rat subchronic toxicity studies from 289 pharmaceutical compounds with the aim to predict the tumor outcome of carcinogenicity studies in this species. The results were obtained from the assessment reports available at the Medicines Evaluation Board of the Netherlands for 289 pharmaceutical compounds that had been shown to be non-genotoxic. One hundred forty-three of the 239 compounds not inducing putative preneoplastic lesions in the subchronic study did not induce tumors in the carcinogenicity study [true negatives (TNs)], whereas 96 compounds were categorized as false negatives (FNs) because tumors were observed in the carcinogenicity study. Of the remaining 50 compounds, 31 showed preneoplastic lesions in the subchronic study and tumors in the carcinogenicity study [true positives (TPs)], and 19 only showed preneoplastic lesions in subchronic studies but no tumors in the carcinogenicity study [false positives (FPs)]. In addition, we then re-assessed the prediction of the tumor outcome by integrating the pharmacological properties of these compounds. These pharmacological properties were evaluated with respect to the presence or absence of a direct or indirect proliferative action. We found support for the absence of cellular proliferation for 204 compounds (TN). For 67 compounds, the presence of cellular hyperplasia as evidence for proliferative action could be found (TP). Therefore, this approach resulted in an ability to predict non-carcinogens at a success rate of 92% and the ability to detect carcinogens at 98%. The combined evaluation of pharmacological and histopathological endpoints eventually led to only 18 unknown outcomes (17 categorized as FN and 1 as FP), thereby enhancing both the negative and positive predictivity of an evaluation based upon histopathological evaluation only. The data show the added value of a consideration of the pharmacological properties of compounds in relation to potential class effects, both in the negative and positive direction. A high negative and a high positive predictivity will both result in waiving the need for conducting 2-year rat carcinogenicity studies, if this is accepted by Regulatory Authorities, which will save large numbers of animals and reduce drug development costs and time

Toxicological characterization of diesel engine emissions using biodiesel and a closed soot filter

This study was designed to determine the toxicity (oxidative stress, cytotoxicity, genotoxicity) in extracts of combustion aerosols. A typical Euro Ill heavy truck engine was tested over the European Transient Cycle with three different fuels: conventional diesel EN590, biodiesel EN14214 as 8100 and blends with conventional diesel (B5, 810, and 1320) and pure plant oil DIN51605 (PPO). In addition application of a (wall flow) diesel particulate filter (DPF) with conventional diesel EN590 was tested. The use of B100 or PPO as a fuel or the DPF reduced particulate matter (PM) mass and numbers over 80%. Similarly, significant reduction in the emission of chemical constituents (EC 90%, (oxy)-PAH 70%) were achieved. No significant changes in nitro-PAH were observed. The use of B100 or PPO led to a NOx increase of about 30%, and no increase for DPF application. The effects of B100, PPO and the DPF on the biological test results vary strongly from positive to negative depending on the biological end point. The oxidative potential, measured via the DDT assay, of the B100 and PPO or DPF emissions is reduced by 95%. The cytotoxicity is increased for B100 by 200%. The measured mutagenicity, using the Ames assay test with TA98 and YG1024 strains of Salmonella typhimurium indicate a dose response for the nitroarene sensitive YG1024 strain for B100 and PPO (fold induction: 1.6). In summary B100 and PPO have good potential for the use as a second generation biofuel resulting in lower PM mass, similar to application of a DPF, but caution should be made due to potential increased toxicity. Besides regulation via mass, the biological reactivity of exhaust emissions of new (bio)fuels and application of new technologies, needs attention. The different responses of different biological tests as well as differences in results between test laboratories underline the need for harmonization of test methods and international cooperation. (C) 2011 Elsevier Ltd. All rights reserved