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Item does not contain fulltext Human bone marrow-derived mesenchymal stem cells (BMSCs) are clinically promising to repair damaged articular cartilage. This study investigated TWIST1, an important transcriptional regulator in mesenchymal lineages, in BMSC chondrogenesis. We hypothesized that downregulation of TWIST1 expression is required for in vitro chondrogenic differentiation. Indeed, significant downregulation of TWIST1 was observed in murine skeletal progenitor cells during limb development (N = 3 embryos), and during chondrogenic differentiation of culture-expanded human articular chondrocytes (N = 3 donors) and isolated adult human BMSCs (N = 7 donors), consistent with an inhibitory effect of TWIST1 expression on chondrogenic differentiation. Silencing of TWIST1 expression in BMSCs by siRNA, however, did not improve chondrogenic differentiation potential. Interestingly, additional investigation revealed that downregulation of TWIST1 in chondrogenic BMSCs is preceded by an initial upregulation. Similar upregulation is observed in non-chondrogenic BMSCs (N = 5 donors); however, non-chondrogenic cells fail to downregulate TWIST1 expression thereafter, preventing their chondrogenic differentiation. This study describes for the first time endogenous TWIST1 expression during in vitro chondrogenic differentiation of human BMSCs, demonstrating dynamic regulation of TWIST1 expression whereby upregulation and then downregulation of TWIST1 expression are required for chondrogenic differentiation of BMSCs. Elucidation of the molecular regulation of, and by, TWIST1 will provide targets for optimization of BMSC chondrogenic differentiation culture.

Marco Faccini,1 Roberto Leone,2 Benedetta Pajusco,1 Gianluca Quaglio,1 Rebecca Casari,1 Anna Albiero,1 Monia Donati,2 Fabio Lugoboni11Department of Internal Medicine, Addiction Unit, 2Pharmacology Unit, Reference Center for Education and Communication within the World Health Organization Program for International Drug Monitoring, University Hospital of Verona, Verona, ItalyBackground: The purpose of this study was to determine, in the context of a hospital addiction unit, which benzodiazepines were abused and to look for correlations with the characteristics of detoxified patients.Methods: A retrospective study was carried out using the database of hospital admissions to the addiction unit for detoxification from 2003 to 2010.Results: Of 879 admissions to the addiction unit during the seven-year period, 281 were for benzodiazepines. The percentage of patients addicted only to benzodiazepines was higher among females than males. Benzodiazepine consumption had started as a drug addiction behavior in only 10% of cases. The main sources of prescription identified were general practitioners (52% of cases) or compliant pharmacists (25%). Overall, 15 different benzodiazepines were abused, with lormetazepam being the most commonly used (by 123 patients, 43.8% of the total).Conclusion: Our data show that, outside the population of multidrug addicts, there is an underestimated group of chronic benzodiazepine consumers who are often not referred to medical institutions for treatment. Even in the group of patients addicted to one substance only, we observed an abnormal number of requests for detoxification from lormetazepam, which appears to be more "popular" than other benzodiazepines. This drug should be prescribed according to stricter criteria and submitted to closer control.Keywords: lormetazepam, benzodiazepines, addiction, inpatient detoxification