Open nanofluidic films with rapid transport and no analyte exchange for ultra-low sample volumes.

Moving to ultra-low (<100 nL) sample volumes presents numerous challenges, many of which can be resolved by implementation of open nanofluidic films. These nanofluidic films are fabricated using a hexagonal network of gold-coated open microchannels which capture all of the following innovative advantages: (1) sample volumes of <100 nL cm-2; (2) zero analyte exchange and loss with the film materials; (3) rapid and omni-directional wicking transport of >500 nL min-1 per square of film; (4) ultra-simple roll-to-roll fabrication; (5) stable and bio-compatible super-hydrophilicity for weeks in air by peptide surface modification. Validation includes both detailed in vitro characterization and in vivo validation with sweat transport from the human skin. Sampling times (skin-to-sensor) of <3 min were achieved, setting new benchmarks for the field of wearable sweat sensing. This work addresses significant challenges for sweat biosensing, or for any other nano-liter regime (<100 nL) fluid sampling and sensing application.

Preclinical neurochemical and electrophysiological profile of 1192U90, a potential antipsychotic.

11192U90 was submitted to receptor binding and monoamine uptake assays. It bound potently at serotonin 5-HT2, dopaminergic D2, serotonin 5-HT1A, and adrenergic alpha 1 and alpha 2 receptors. It also bound to dopaminergic D1, serotonin 5-HT3, serotonin 5-HT4, and sigma sites, albeit with lower affinity. It was essentially inactive at 22 other sites, including those for cholinergic M1 and M2. It weakly inhibited uptake of 3H-norepinephrine, 3H-serotonin and 3H-dopamine. Acute doses of 1192U90 (5 and 20 mg/kg P.O.) increased whole-brain levels of dopamine metabolites but did not affect levels of norepinephrine, dopamine, and serotonin. Subcutaneous injection of 1192U90 (0.8 mg/kg/day) and clozapine (20 mg/kg/day) for 28 days preferentially decreased the number of spontaneously active dopamine cells in the ventral tegmental area (VTA) but not the substantia nigra (SN) of rats, as measured by population sampling. This outcome is characteristics of atypical antipsychotics like clozapine. Acute injections of 1192U90 reversed the rate-inhibiting effects of microiontophoretically applied dopamine and intravenously injected apomorphine and d-amphetamine on dopamine cell firing. Intravenous injection or iontophoretic application of 1192U90 or the 5-HT1A agonist (+/-)8-OH-DPAT inhibited the firing rates of dorsal raphe nucleus (DRN) neurons in rats, and the effects of both compounds were blocked by iontophoretically applied S(-) propranolol, a 5-HT1A antagonist. The results suggest that 1192U90 is a preferential dopamine D2 antagonist as well as a 5-HT1A agonist that may prove to be an atypical antipsychotic.

Clinical pharmacogenomics: applications in pharmaceutical R&D.

Within the pharmaceutical industry, the application of clinical pharmacogenomics promises to enhance the discovery of drug response markers, reduce the size and expense of clinical drug trials and provide a new tool for addressing regulatory approval issues. Today, pharmacogenomics is primarily applied early in clinical drug development by prospective genotyping in Phase I trials, to ensure that a subject population is representative with respect to drug metabolism phenotypes. The banking of genetic material from later stage trials for retrospective studies on drug response is becoming more frequent, but is not yet standard in the industry. This article provides an overview of the driving forces that are encouraging pharmacogenomic strategy development in the pharmaceutical industry, and the significance of polymorphisms in drug metabolizing enzymes (DMEs) and target proteins.

Inhibition of the acute toxicity of methyl chloride in male B6C3F1 mice by glutathione depletion.

Previous data have demonstrated that methyl chloride (MeCl) is toxic to B6C3F1 mice under both acute and chronic exposure conditions, and that conjugation of MeCl with glutathione (GSH) is a key step in the metabolism of MeCl. This study examined the role of GSH in mediating the acute toxicity of MeCl to liver, kidney, and brain of male B6C3F1 mice. The lethal effects of a single 6-hr inhalation exposure of B6C3F1 males to 2500 ppm MeCl were completely prevented by pretreatment with the GSH synthesis inhibitor, L-buthionine-S,R-sulfoximine (4 mmol L-BSO/kg, ip 1.5 hr prior to MeCl exposure). GSH levels (measured as nonprotein sulfhydryl) in liver and kidney were depleted to 19 and 25% of control values, respectively, at the start of the exposure; the ratio of dead/exposed mice during the 18-hr postexposure declined from 14/15 mice to 0/10. Also, the LC50 for MeCl increased from 2200 to 3200 ppm in male mice pretreated with BSO. The hepatic toxicity of MeCl was detected by increased alanine aminotransferase (ALT) activities in serum 18 hr after a 6-hr exposure to 1500 ppm MeCl (2147 +/- 1327 IU/liter vs 46 +/- 6 in controls). Liver toxicity was inhibited when B6C3F1 males were depleted of GSH prior to MeCl exposure by BSO pretreatment (43 +/- 2), fasting (100 +/- 47), or injection of diethyl maleate (42 +/- 16). The effects of GSH depletion on MeCl toxicity to brain and kidney were determined in B6C3F1 males exposed to 1500 ppm MeCl 6 hr/day, 5 days/week for 2 weeks, with and without daily pretreatment with 2 mmol L-BSO/kg. This dose of BSO depleted hepatic and renal GSH by 28 and 60%, respectively, at the start of MeCl exposure. BSO-pretreated mice were protected from the central nervous system toxicity of MeCl, as assessed by microscopic examination of the granule cell layer of the cerebellum. BSO pretreatment also inhibited the renal toxicity of MeCl as measured by incorporation of [3H]thymidine ([3H]TdR) into renal DNA, an indicator of cell regeneration after cortical necrosis. [3H]TdR incorporation was 105 +/- 10,337 +/- 40, and 60 +/- 15 dpm/microgram DNA in nonexposed controls, MeCl, and MeCl + BSO treatment groups, respectively. These results indicate that GSH is an important component in the toxicity of MeCl to multiple organ systems in B6C3F1 mice. Reaction of MeCl with GSH appears to constitute a mechanism of toxication, contrary to the role usually proposed for GSH in detoxifying xenobiotics.

Rapid high-performance liquid chromatographic method for the determination of propranolol levels in canine and feline plasma.

A sensitive high-performance liquid chromatographic method that does not require organic extraction has been developed for the determination of propranolol levels in canine and feline plasma. Equal volumes of plasma and a mixture of methanol-acetonitrile-0.1 M sodium hydroxide (3:3:4, v/v/v) were added to a microseparation unit with a 10,000 molecular mass cut-off filter. The ultrafiltrate was analyzed by reversed-phase liquid chromatography with fluorimetric detection. The consistency of the recoveries obtained eliminated the need for an internal standard (coefficients of variation less than 4%). Linear regressions for the standard curves (2.5-100 ng/ml) gave correlation coefficients above 0.9955. The detection limit was 1 ng/ml. The assay retains high sensitivity while eliminating laborious sample preparation.