The stem loop II within the 5' nontranslated region of clinical coxsackievirus B3 genomes determines cardiovirulence phenotype in a murine model

Coxsackievirus B3 (CVB3) is a principal viral cause of acute myocarditis in humans and has been implicated in the pathogenesis of dilated cardiomyopathy. It has been demonstrated elsewhere that, for 2 wild-type CVB3 strains, the primary molecular determinant of cardiovirulence phenotype localizes to the 5' nontranslated region (5' NTR). Here in this study, through construction of CVB3 chimeras, the predicted stem loop (SL) II within the 5' NTR has been identified as a primary viral determinant of cardiovirulence. Replication assays in cardiac-derived murine fibroblasts revealed that only cardiovirulent strains grow robustly at 37 degrees C, whereas all virus strains replicate efficiently in HeLa cells. Computational analyses of RNA secondary structure suggest that the predicted SLII of the noncardiovirulent isolate differs significantly from that of myocarditic strains. These results indicate that, for clinical CVB3 isolates, the major determinant of cardiovirulence localizes to the predicted SLII. The identity of this higher-order RNA structure may be essential for productive infection of cardiac cells.     

Harnessing the natural regenerative potential of the dental pulp

Biological solutions for the repair and regeneration of the dental tissues offer significant potential for improved clinical treatment outcomes. Translation of dental tissue-engineering approaches to the clinic will make considerable contributions to these outcomes in the future, but exploiting the natural regenerative potential of dentin-pulp to enhance wound-healing responses offers solutions for maintaining pulp vitality now. Strategies to harness the natural regenerative potential of the pulp must be based on a sound biological understanding of the cellular and molecular events taking place, and require careful consideration of the interplay of infection, inflammation, and regeneration.     

Progressive resistance to a selective serotonin reuptake inhibitor but not to cognitive therapy in the treatment of major depression

Recent research suggests that there may be a reduction in therapeutic response after multiple administrations of antidepressant drug (AD) therapy in patients with major depressive disorder. This study assessed the response to AD therapy and cognitive therapy (CT) of patients with a history of prior AD exposures. A sample of 240 patients with moderate-to-severe major depressive disorder entered a randomized controlled trial comparing pharmacotherapy with paroxetine to CT. Treatment was administered for 16 weeks. History of prior AD exposure was assessed with structured interviews, self-report, and medical records. Analyses were conducted using hierarchical linear models on the intent-to-treat sample. After controlling for various demographic and clinical factors, more prior AD exposures predicted poor response to paroxetine therapy but not to CT, as measured by the Hamilton Rating Scale for Depression (Hamilton, 1960; Williams, 1988). Whereas CT outcome was not significantly related to the number of prior AD exposures, a higher number of prior AD exposures was significantly associated with a lower response to paroxetine. If these findings are replicated in methodologically rigorous studies of paroxetine and other antidepressants, CT should be recommended, in preference to AD, for patients with multiple prior AD exposures.     

Selective blockade of 5-hydroxytryptamine (5-HT)7 receptors enhances 5-HT transmission, antidepressant-like behavior, and rapid eye movement sleep suppression induced by citalopram in rodents

Evidence has accumulated supporting a role for 5-hydroxytryptamine (5-HT)7 receptors in circadian rhythms, sleep, and mood disorders, presumably as a consequence of the modulation of 5-HT-mediated neuronal activity. We hypothesized that a selective 5-HT7 receptor antagonist, (2R)-1-[(3-hydroxyphenyl)sulfonyl]-2-[2-(4-methyl-1-piperidinyl)ethyl]-pyrrolidine (SB-269970), should increase activity of 5-HT neurons and potentiate the effect of selective serotonin reuptake inhibitors (citalopram). In rats, administration of 3 mg/kg s.c. citalopram alone increased the extracellular concentration of 5-HT. This effect of citalopram on extracellular 5-HT concentration was significantly enhanced by an ineffective dose of SB-269970. Combining this dose of SB-269970 with a low dose of citalopram also resulted in a significant increase in extracellular concentration of 5-HT, suggesting a potentiation of neurochemical effects. In mice, citalopram and SB-269970 dose-dependently decreased immobility time in the tail suspension test. The dose-effect curve of citalopram was shifted leftward by coadministration of an effective dose of SB-269970. Furthermore, combining ineffective doses of citalopram and SB-269970 also resulted in a significant decrease of immobility time in the tail suspension test, suggesting potentiation of antidepressant-like effects. In rats, SB-269970 potentiated the increase of rapid eye movement (REM) latency and the REM sleep decrease induced by citalopram. SB-269970 also reversed the increase in sleep fragmentation induced by citalopram. Rat plasma and brain concentrations of citalopram were not affected by coadministration of SB-269970, arguing for a pharmacodynamic rather than a pharmacokinetic mechanism. Overall, these results indicate that selective blockade of 5-HT7 receptors may enhance the antidepressant efficacy of citalopram and may provide a novel therapy to alleviate sleep disturbances associated with depression.     

Factitious diarrhea induced by stimulant laxatives: accuracy of diagnosis by a clinical reference laboratory using thin layer chromatography

BACKGROUND: Surreptitious ingestion of laxatives can lead to serious factitious diseases that are difficult to diagnose. Most cases involve ingestion of bisacodyl or senna. Thin layer chromatography (TLC) of urine or stool is the only commercially available test for these laxatives. Such testing is considered highly reliable, but its accuracy in clinical practice is unknown. Our aim was to evaluate the reliability of TLC laxative testing by a clinical reference laboratory in the United States. METHODS: Diarrhea was induced in healthy volunteers by ingestion of bisacodyl, senna, or a control laxative (n = 11 for each laxative group). Samples of urine and diarrheal stool were sent in blinded fashion to the clinical reference laboratory for bisacodyl and senna analysis. RESULTS: TLC testing for bisacodyl-induced diarrhea revealed a sensitivity of 73% and specificity of 91% when urine was tested and sensitivity and specificity of 91% and 96%, respectively, when stool was analyzed. When diarrhea was induced by senna, the TLC assay for senna failed to identify even a single urine or stool specimen as positive (zero% sensitivity). CONCLUSIONS: Considering the expected prevalence of surreptitious laxative abuse in patients with chronic idiopathic diarrhea (2.4%-25%, depending on the clinical setting), TLC of urine or stool for bisacodyl by this reference laboratory would often produce misleading results, and testing for senna would have no clinical value. The major problems are false-positive tests for bisacodyl and false-negative tests for senna.