Dimethyl Sulfoxide (DMSO) Exacerbates Cisplatin-Induced Sensory Hair Cell Death in Zebrafish (Danio Rerio).

Dimethyl Sulfoxide (DMSO) Exacerbates Cisplatin-induced Sensory Hair Cell Death in Zebrafish (Danio rerio).

Filed under: Drug and Alcohol Rehabilitation

PLoS One. 2013; 8(2): e55359
Uribe PM, Mueller MA, Gleichman JS, Kramer MD, Wang Q, Sibrian-Vazquez M, Strongin RM, Steyger PS, Cotanche DA, Matsui JI

Inner ear sensory hair cells die following exposure to aminoglycoside antibiotics or chemotherapeutics like cisplatin, leading to permanent auditory and/or balance deficits in humans. Zebrafish (Danio rerio) are used to study drug-induced sensory hair cell death since their hair cells are similar in structure and function to those found in humans. We developed a cisplatin dose-response curve using a transgenic line of zebrafish that expresses membrane-targeted green fluorescent protein under the control of the Brn3c promoter/enhancer. Recently, several small molecule screens have been conducted using zebrafish to identify potential pharmacological agents that could be used to protect sensory hair cells in the presence of ototoxic drugs. Dimethyl sulfoxide (DMSO) is typically used as a solvent for many pharmacological agents in sensory hair cell cytotoxicity assays. Serendipitously, we found that DMSO potentiated the effects of cisplatin and killed more sensory hair cells than treatment with cisplatin alone. Yet, DMSO alone did not kill hair cells. We did not observe the synergistic effects of DMSO with the ototoxic aminoglycoside antibiotic neomycin. Cisplatin treatment with other commonly used organic solvents (i.e. ethanol, methanol, and polyethylene glycol 400) also did not result in increased cell death compared to cisplatin treatment alone. Thus, caution should be exercised when interpreting data generated from small molecule screens since many compounds are dissolved in DMSO.
HubMed – drug

Rapid Diagnosis of Drug Resistance to Fluoroquinolones, Amikacin, Capreomycin, Kanamycin and Ethambutol Using Genotype MTBDRsl Assay: A Meta-Analysis.

Filed under: Drug and Alcohol Rehabilitation

PLoS One. 2013; 8(2): e55292
Feng Y, Liu S, Wang Q, Wang L, Tang S, Wang J, Lu W

There are urgent needs for rapid and accurate drug susceptibility testing of M. tuberculosis. GenoType MTBDRsl is a new molecular kit designed for rapid identification of the resistance to the second-line antituberculosis drugs with a single strip. In recent years, it has been evaluated in many settings, but with varied results. The aim of this meta-analysis was to synthesize the latest data on the diagnostic accuracy of GenoType MTBDRsl in detecting drug resistance to fluoroquinolones, amikacin, capreomycin, kanamycin and ethambutol, in comparison with the phenotypic drug susceptibility test.This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. The search terms of “MTBDRsl” and “tuberculosis” were used on PubMed, EMBASE, and Web of Science. QUADAS-2 was used to assess the quality of included studies. Data were analyzed by Meta-Disc 1.4. We calculated the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and corresponding 95% confidence interval (CI) for each study. From these calculations, forest plots and summary receiver operating characteristic (SROC) curves were produced.Patient selection bias as well as flow and timing bias were observed in most studies. The summarized sensitivity (95% CI) was 0.874(0.845-0.899), 0.826(0.777-0.869), 0.820(0.772-0.862), 0.444(0.396-0.492), and 0.679(0.652-0.706) for fluoroquinolones, amikacin, capreomycin, kanamycin, and ethambutol, respectively. The specificity (95% CI) was 0.971(0.961-0.980), 0.995(0.987-0.998), 0.973(0.963-0.981), 0.993(0.985-0.997), and 0.799(0.773-0.823), respectively. The AUC (standard error) were 0.9754(0.0203), 0.9300(0.0598), 0.9885(0.0038), 0.9689(0.0359), and 0.6846(0.0550), respectively.Genotype MTBDRsl showed good accuracy for detecting drug resistance to fluoroquinolones, amikacin and capreomycin, but it may not be an appropriate choice for kanamycin and ethambutol. The lack of data did not allow for proper evaluation of the test on clinical specimens. Further systematic assessment of diagnostic performance should be carried out on direct clinical samples.
HubMed – drug

Inhibitors of the influenza a virus m2 proton channel discovered using a high-throughput yeast growth restoration assay.

Filed under: Drug and Alcohol Rehabilitation

PLoS One. 2013; 8(2): e55271
Balgi AD, Wang J, Cheng DY, Ma C, Pfeifer TA, Shimizu Y, Anderson HJ, Pinto LH, Lamb RA, Degrado WF, Roberge M

The M2 proton channel of the influenza A virus is the target of the anti-influenza drugs amantadine and rimantadine. The effectiveness of these drugs has been dramatically limited by the rapid spread of drug resistant mutations, mainly at sites S31N, V27A and L26F in the pore of the channel. Despite progress in designing inhibitors of V27A and L26F M2, there are currently no drugs targeting these mutated channels in clinical trials. Progress in developing new drugs has been hampered by the lack of a robust assay with sufficient throughput for discovery of new active chemotypes among chemical libraries and sufficient sensitivity to provide the SAR data essential for their improvement and development as drugs. In this study we adapted a yeast growth restoration assay, in which expression of the M2 channel inhibits yeast growth and exposure to an M2 channel inhibitor restores growth, into a robust and sensitive high-throughput screen for M2 channel inhibitors. A screen of over 250,000 pure chemicals and semi-purified fractions from natural extracts identified 21 active compounds comprising amantadine, rimantadine, 13 related adamantanes and 6 non-adamantanes. Of the non-adamantanes, hexamethylene amiloride and a triazine derivative represented new M2 inhibitory chemotypes that also showed antiviral activity in a plaque reduction assay. Of particular interest is the fact that the triazine derivative was not sufficiently potent for detection as an inhibitor in the traditional two electrode voltage clamp assay for M2 channel activity, but its discovery in the yeast assay led to testing of analogues of which one was as potent as amantadine.
HubMed – drug

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