Modulation of energy deficiency in Huntington's disease via activation of the peroxisome proliferator-activated receptor gamma.

Huntington's disease (HD) is a neurodegenerative disease caused by the expansion of a CAG trinucleotide repeat in exon 1 of the huntingtin (HTT) gene. Here, we report that the transcript of the peroxisome proliferator-activated receptor-γ (PPARγ), a transcription factor that is critical for energy homeostasis, was markedly downregulated in multiple tissues of a mouse model (R6/2) of HD and in lymphocytes of HD patients. Therefore, downregulation of PPARγ seems to be a pathomechanism of HD. Chronic treatment of R6/2 mice with an agonist of PPARγ (thiazolidinedione, TZD) rescued progressive weight loss, motor deterioration, formation of mutant Htt aggregates, jeopardized global ubiquitination profiles, reduced expression of two neuroprotective proteins (brain-derived neurotrophic factor and Bcl-2) and shortened life span exhibited by these mice. By reducing HTT aggregates and, thus, ameliorating the recruitment of PPARγ into HTT aggregates, chronic TZD treatment also elevated the availability of the PPARγ protein and subsequently normalized the expression of two of its downstream genes (the glucose transporter type 4 and PPARγ coactivator-1 alpha genes). The protective effects described above appear to have been exerted, at least partially, via direct activation of PPARγ in the brain, as TZD was detected in the brains of mice treated with TZD and because a PPARγ agonist (rosiglitazone) protected striatal cells from mHTT-evoked energy deficiency and toxicity. We demonstrated that the systematic downregulation of PPARγ seems to play a critical role in the dysregulation of energy homeostasis observed in HD, and that PPARγ is a potential therapeutic target for this disease.

Unexpected identification of a bupivacaine analog from smuggling by using single-crystal X-ray diffraction analysis: N-(2,6-dimethylphenyl)-1-phenethylpiperidine-2-carboxamide.

The identification of new psychoactive substances (NPSs) is essential against drug abuse, especially for "new" drugs that are not regulated by international drug conventions. A suspicious powder seized by the officers of Taipei Customs Administration of Taiwan was sent to this laboratory for analysis by using gas chromatography-mass spectrometry (GCMS), liquid chromatography-high resolution mass spectrometry (LCHRMS), proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR) with distortionless enhancement by polarization transfer (DEPT) at proton pulses of 45°, 90°, and 135°, two-dimensional correlation NMR measurements (2D_COSY), and heteronuclear single-quantum correlation NMR measurements (2D_HSQC). However, the structure of this "unknown" sample was difficult to identify. Alternatively, single-crystal X-ray crystallography was applied for structural determination after the crystallization of the compound in methanol. The structure was thus identified as N-(2,6-dimethylphenyl)-1-phenethylpiperidine-2-carboxamide (NDMPPPC), an analog of bupivacaine with similar pharmacological effects to those of cocaine, ketamine and morphine. The identification of NDMPPPC is in accordance with all mass fragments and NMR signal data, demonstrating that single-crystal X-ray diffraction can be used for structural determination, especially for complicated structures of "new" drugs or "unknown" samples. The seizure of NDMPPPC from smuggling indicates a great potential to become part of the next generation of NPSs.

Evaluating misoprostol content in pregnant women with hourly oral administration during labor induction by microElution solid phase extraction combined with liquid chromatography tandem mass spectrometry.

Misoprostol is a widely used alternative of prostaglandin for labor induction. Based on previous studies, we envision that small and frequent oral dosage of misoprostol is an effective method for labor induction. To monitor the misoprostol content during labor induction, a rapid, sensitive, and selective microElution solid phase extraction (µElution SPE) combined with liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed. Using µElution SPE could minimize the sample consumption and elution volume in order to maximize the sample enrichment and throughput. The misoprostol acid, a metabolite of misoprostol, was gradient separated in a Bidentate C18 column, then quantified by highly-selective reaction monitoring (H-SRM) in a total run time of 6min. The developed method was optimized and validated in human plasma, and showed linear range of 0.01-10ng/mL. The limit of detection (LOD) was 0.001ng/mL. The recovery ranged from 89.0 to 96.0%, and no significant matrix effect or carryover was observed. The precision, accuracy and stability were met with the criteria of U.S. FDA guidance. The developed method was successfully applied to evaluate misoprostol concentration during labor induction in pregnant women. The concentration-time profiles approves that hourly oral administration of misoprostol is a safe and effective method without drug accumulation for labor induction.

Purge-assisted headspace solid-phase microextraction combined with gas chromatography/mass spectrometry for the determination of trace nitrated polycyclic aromatic hydrocarbons in aqueous samples.

This study describes a new procedure, namely, purge-assisted headspace solid phase microextraction combined with gas chromatography/negative ion chemical ionization mass spectrometry (PA/HS-SPME-GC/NICI-MS), which is used to determine seven nitrated polycyclic aromatic hydrocarbons (NPAHs) in aqueous samples. High extraction efficiency was obtained with PA/HS-SPME with polydimethylsiloxane (PDMS) fiber coating. A programmable temperature vaporizing (PTV) inlet was used in the desorption process. Selected ion monitoring (SIM) was used for quantitative and qualitative purposes. The linear range of detection of the proposed method was 5-5000 pg/mL with coefficients of determination between 0.995 and 0.999. Limits of detection (LODs) for seven NPAHs were 0.01-0.06 pg/mL. The relative standard deviation was below 12.7% at a concentration of 50 pg/mL. Compared with headspace-solid phase microextraction (HS-SPME), the purge procedure enhanced the extraction efficiency for high boiling point analytes, such as 7-nitrobenz[a]anthracene (7-NBA) and 6-nitrochrysene (6-NC). The proposed method provides a sensitive method for NPAH analysis at the pg/mL level. The application of the proposed method for the determination of trace NPAHs in real samples was investigated by analyzing aqueous samples from rivers. The concentrations of NPAHs detected from the samples ranged from 5.2 to 7.5 pg/mL. This method was applied successfully in the analysis of trace NPAHs in river samples.