Simultaneous determination of methamphetamine, 3,4-methylenedioxy-N-methylamphetamine, 3,4-methylenedioxy-N-ethylamphetamine, N,N-dimethylamphetamine, and their metabolites in urine by liquid chromatography-electrospray ionization-tandem mass spectrometry

A liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) method was developed and validated for the simultaneous detection and quantification of seven amphetamine derivatives (amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxy-N-amphetamine (MDA), 3,4-methylenedioxy-N-methamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), N,N-dimethylamphetamine (DMA), and N,N-dimethylamphetamine-N-oxide (DMANO)) in human urine. Seven deuterium-labeled compounds were prepared for use as internal standards to quantify the analytes. One milliliter of urine was combined with 1 mL of 0.2 M sodium carbonate buffer solution (pH 9.0) before solid phase extraction (SPE). An Oasis HLB SPE column followed by chromatographic separation on a Capcell Pak C18 MG-II column (150 × 2.0 mm I.D., 5 μm) and electrospray mass spectrometry with multiple reaction monitoring were used for selective and sensitive detection. The use of ammonium formate (5 mM, pH adjusted to 4.0 with formic acid, Solvent A) and acetonitrile (Solvent B) as the mobile phase at a flow rate of 230 μL/min was found to be the most effective for the separation. The linear ranges were 5.0–1000 ng/mL for AP, MDA, MDMA, MDEA, DMA, and DMANO and 10.0–1000 ng/mL for MA, with good correlation coefficients (r² > 0.996). The intra-day, inter-day, and interperson precisions were within 14.6%, 12.1% and 15.5%, respectively. The intra-day, inter-day, and interperson accuracies were between ?11.6 and 9.0%, ?7.9 and 2.3%, and ?13.2 and 4.3%, respectively. The limits of detection (LODs) for each analytical compound were lower than 1.95 ng/mL. The recovery ranged from 72.3 to 103.3%. The applicability of the developed method was examined by analyzing several urine samples from confirmed drug abusers.     

Fatty acid oxidation in neonatal hepatocytes: effects of sepsis and glutamine

OBJECTIVE: Little is known about fat use during sepsis during the neonatal period. Intramitochondrial O(2) consumption is inhibited in isolated hepatocytes from suckling septic rats and this impairment is reversed by glutamine. We investigated the effect of neonatal sepsis on fat oxidation and whether glutamine can directly affect fatty acid oxidation. METHODS: Suckling Wistar rats (11 d) received an intraperitoneal injection of 300 microg/kg of lipopolysaccharide (Escherichia coli 055:B5); controls received normal saline. At 2 h, hepatocytes were isolated. Hepatocytes were incubated at 37 degrees C with 0.5 mM [1-(14)C]palmitate or 0.5 mM [1-(14)C]palmitate plus 10 mM glutamine. After 1 h, the perchloric acid-soluble (14)C-radioactivity (representing mainly ketone bodies) and (14)CO(2) were measured. Hepatocyte O(2) consumption from 0.5 mM palmitate was measured with and without 2.5 ng/mL myxothiazol to estimate intramitochondrial O(2) consumption. RESULTS: There were no significant differences in fatty acid oxidation between control and endotoxemic hepatocytes measured as acid-soluble radioactivity (which represents mainly ketogenesis, plus Krebs cycle intermediates), as (14)CO(2) production, or as the sum of acid-soluble radioactivity plus (14)CO(2) generation. Glutamine significantly increased fatty acid oxidation (acid-soluble radioactivity plus (14)CO(2)) in hepatocytes from control and endotoxic animals. CONCLUSIONS: The finding of no significant difference in fatty acid oxidation between hepatocytes from control and endotoxemic rats is surprising given that intramitochondrial O(2) consumption from palmitate is decreased. This may reflect altered use of acetyl-coenzyme A to ketone bodies and Krebs cycle intermediates. Glutamine enhanced fatty acid oxidation from control and endotoxemic hepatocytes, suggesting that it may promote substrate oxidation during endotoxemia.     

A High-Throughput Combinatorial Approach for the Discovery of a Cremophor EL-Free Paclitaxel Formulation

Purpose. The purpose of this work was to replace Cremophor-EL in the commercial paclitaxel intravenous formulation, Taxol®, using a novel high-throughput combinatorial formulation approach. Methods. Full factorial combinations of 12 generally regarded as safe excipients at three different concentrations were screened using an automated liquid dispenser. The hit formulations were further optimized to give the final optimized formulation TPI-1. TPI-1 was then tested in rats to compare its pharmacokinetic profile to Taxol®. Results. Of the 9,880 combinations tested in the initial screen, 19 were identified as hit combinations. These were further optimized to give the final formulation TPI-1. When tested in rats, TPI-1 was well tolerated at both the low and high doses of 5 mg/kg and 10 mg/kg, whereas Taxol® killed all the rats at the high dose. TPI-1 experienced slower elimination compared to Taxol®. Similar to Taxol®, TPI-1 also exhibited nonlinear pharmacokinetics. Conclusions. This study demonstrated the power of a high-throughput combinatorial approach for alternative paclitaxel formulations. We believe that this approach can be applied to drug formulation in general and it can improve the speed and efficiency of drug formulation design.     

Linking Chinese medicine and G-protein-coupled receptors

Following the purification of the immunosuppressant ISP-1 from a Chinese medicine, Japanese scientists have developed a more potent immune modulator, FTY720, that induces T-cell homing. FTY720, a promising immunosuppressant for use in patients with tissue transplants and autoimmune diseases, is currently in clinical trials. Two recent studies have elucidated that the mechanism of action of FTY720 is via a subset of G-protein-coupled receptors for the lysophospholipid mediator sphingosine-1-phosphate.     

A bioassay for mosquito repellency against Aedes aegypti: method validation and bioactivities of DEET analogues

Objectives Vector‐borne diseases are still a major mortality factor in Africa and South‐east Asia and effective mosquito repellents are therefore needed. An efficient and safe in‐vitro assay system using artificial blood and skin substitute could facilitate the development of novel repellents, as most assays currently rely on human subjects or vertebrate whole blood. Moreover, examining the skin permeation profiles could provide safer mosquito repellents. The new assay system could serve as an initial system for testing new repellent candidates upon validation with DEET and its analogues. Methods N,N‐Diethyl‐meta‐toluamide (DEET) and five analogues were synthesised and used to validate a novel in‐vitro bioassay using artificial blood and collagen membrane. Repellency against Aedes aegypti was correlated with lipophilicity and skin permeation. Key findings The new in‐vitro assay showed good reproducibility (interday relative standard deviation <10% at high concentrations). Four of the five DEET analogues showed repellency similar or superior to that of DEET. Repellency correlated linearly with lipophilicity but stronger repellents tended to permeate skin better. Conclusions The new in‐vitro assay using blood substitute and collagen membrane significantly simplifies screening of possible mosquito repellents. Lipophilicity as well as skin permeation profiles should be considered before testing of compounds that are candidates for mosquito repellents.     

Niraparib: A Review in Ovarian Cancer

Niraparib (Zejula^®), a poly (ADP-ribose) polymerase (PARP) inhibitor, is approved for the maintenance treatment of recurrent, epithelial ovarian, fallopian tube, or primary peritoneal cancer in patients who are in complete or partial response to platinum-based chemotherapy. Approval was based on the results of the randomized, double-blind, placebo-controlled phase III NOVA trial. In NOVA, niraparib significantly prolonged progression-free survival (primary endpoint), chemotherapy-free interval and time to first subsequent therapy compared with placebo in patients with recurrent, platinum-sensitive, high grade serous ovarian, fallopian tube or primary peritoneal cancer. The beneficial effects of niraparib were consistent regardless of BRCA mutation or homologous recombination deficiency (HRD) status. Niraparib had a manageable tolerability profile, with the majority of grade 3 or 4 adverse events being haematologic abnormalities (e.g. thrombocytopenia, anaemia, neutropenia). Adverse events were generally well managed with dose interruption or modification of niraparib. Current evidence suggests that niraparib is an effective new option with a manageable tolerability profile for the maintenance treatment of recurrent, platinum-sensitive epithelial ovarian, fallopian tube, or primary peritoneal cancer in adults, with or without BRCA1/2 mutation or HRD.     

Trichostatin inhibits the growth of ACHN renal cell carcinoma cells via cell cycle arrest in association with p27, or apoptosis

We investigated the in vitro effect of trichostatin (histone deacetylase inhibitor) on cell proliferation, cell cycle regulation and apoptosis in renal cell carcinoma cell lines. Trichostatin significantly inhibited the proliferation of all six cell lines examined in dose-dependent manner with IC50 of about 125-250 nM. Trichostatin (72-h incubation) induced a G1 phase arrest in ACHN, Caki-1, Caki-2 and Renca cell lines and a G2-M phase arrest in A498 cells. When we examined the effects of this drug on ACHN cells, trichostatin decreased the levels of CDK4, CDK6, cyclin D1 and cyclin A proteins. p27 protein was increased by trichostatin. In addition, trichostatin markedly enhanced the binding of p27 with CDK2 and CDK4. Furthermore, the activities of CDK2, CDK4- and CDK6-associated kinase were reduced and the lack of the CDK activity was paralleled by increased hypophosphorylation of Rb protein. Trichostatin also induced apoptosis in all the renal cell carcinoma cell lines. Apoptotic process of ACHN cells was associated with the changes of Bcl-2, caspase-9, caspase-3, caspase-7 proteins as well as mitochondria transmembrane potential (deltapsim) loss. Taken together, these results demonstrate that trichostatin inhibits the growth of renal cell carcinoma cells via cell cycle arrest or apoptosis.     

Estrogens in female thyroid cancer: alteration of urinary profiles in pre- and post-operative cases

To evaluate the potential effect of estrogens in premenopausal female thyroid cancer, the concentrations of 14 estrogens were quantitatively determined in the urine of pre- and post-operative patients with thyroid papillary cancer (18 patients case, 26 approximately 54 years) and normal female subjects (20 cases, 31 approximately 52 years). The highly sensitive gas chromatography-mass spectrometry-selected ion-monitoring method was used for estrogens analysis. And an estrogen-oxidative metabolism and 16alpha-hydroxyestrone to 2-hydroxyestrone (16alpha-OH E1/2-OH E1) which is the two primary and competing site of estrogen-oxidation, were determined. Catechol estrogens, including 2-OH E1, were also increased without significant changes of the other estrogen metabolites in pre-operative patients with thyroid papillary cancer compared with normal subjects. The lowest mean value of 16alpha-OH E1/2-OH E1 was remarked in pre-operative patients, and it was significantly different from the ratio of post-operative cases. As a result, it is suggested that the increase of 2-hydroxylation in estrogen metabolism may have a significant association with female thyroid cancer.