Changes of certain pharmacological and biochemical indices in acute methylglyoxal poisoning.

Methylglyoxal in doses over 25 mg/kg injected intravenously in cats and rabbits produces distinct changes in the cardiovascular and respiratory systems, but has no effect on respiration or circulation when injected intraperitoneally even in doses up to 1 g/kg. The effect of MG on blood pressure depends on the species of the animal. The effects of MG are dose-related and dependent on the route of its administration. Biochemical studies showed a significant rise in serum activities of creatine kinase (EC 2-7-3-2), lactate dehydrogenase (EC 1-1-1-27) and aspartate aminotransferase (EC 2-6-1-1-) after intraperitoneal injection of MG in the dose of 200 mg/kg in rabbits and 500 mg/kg in rats. The observed changes probably indicate damage of muscle tissue by MG, presumably as a result of low content of one of the glyoxalases in the muscles of the experimental animals. Elevation of glucose levels by MG was probably an adrenergic effect. These biochemical changes can serve to evaluate toxicity of MG preparations, which exhibit variations probably owing to varying degree of polymerization.     

Analytical Chiral Separation of the Stereoisomers of a Novel Carbonic Anhydrase Inhibitor and Its Deethylated Metabolite,and the Assignment of Absolute Configuration of the Human Metabolite and Chiral Degradation Products

Several approaches to the separation of four stereoisomers, 1–4, of a novel, topically active, carbonic anhydrase inhibitor, 1, with two chiral centers in the molecule and four isomers, 5–8, of its chiral metabolite, 5, were evaluated. These methods include nonchiral derivatization followed by separation on chiral stationary phases (CSPs) and chiral derivatization and separation on nonchiral columns and on CSPs. Baseline separation of stereoisomers 1–4 was achieved in less than 15 min after chiral derivatization with (S)-(+)-l-(l-naphthyl)ethyl isocyanate (NEIC) and chiral chromatography on a (R)-N-(3,5-dinitrobenzoyl)phenyl glycine (DNBPG) column under normal phase (NP) conditions. Similarly, isomers 5-8 were baseline separated in less than 20 min after derivatization with NEIC and chromatography on nonchiral (nitrophenyl) and chiral [(S)-(3,5-dinitrobenzoyl)leucine; DNBL] columns in series under the same NP chromatographic conditions. Only partial separation of the diastereomeric derivatives was observed on a variety of nonchiral columns. In addition, all other direct and indirect chiral separation approaches gave only partial separation of at least two stereoisomers within the group of 1–4 or 5–8. The details of chiral separations using various methods and separation () and capacity factors (k) of the derivatized isomers 1–8 on a series of chiral and nonchiral columns are presented. Using these methods, the absolute configuration of the human metabolite of 1 was established as S ₁ S ₂ (5), and the heat (HD) and light (LD) degradation products of 1 as R ₁ S ₂ (3) and S₁ S ₂ (5), respectively.     

Validation of temperature methods for the estimation of pre-appearance interval in carrion insects

The pre-appearance interval (PAI) is an interval preceding appearance of an insect taxon on a cadaver. It decreases with an increase in temperature in several forensically-relevant insects. Therefore, forensic entomologists developed temperature methods for the estimation of PAI. In the current study these methods were tested in the case of adult and larval Necrodes littoralis (Coleoptera: Silphidae), adult and larval Creophilus maxillosus (Coleoptera: Staphylinidae), adult Necrobia rufipes (Coleoptera: Cleridae), adult Saprinus semistriatus (Coleoptera: Histeridae) and adult Stearibia nigriceps (Diptera: Piophilidae). Moreover, factors affecting accuracy of estimation and techniques for the approximation and correction of predictor temperature were studied using results of a multi-year pig carcass study. It was demonstrated that temperature methods outperform conventional methods. The accuracy of estimation was strongly related to the quality of the temperature model for PAI and the quality of temperature data used for the estimation. Models for larval stage performed better than models for adult stage. Mean temperature for the average seasonal PAI was a good initial approximation of predictor temperature. Moreover, iterative estimation of PAI was found to effectively correct predictor temperature, although some pitfalls were identified in this respect. Implications for the estimation of PAI are discussed.     

Simultaneous determination of unlabeled and carbon-13-labeled etoricoxib, a new cyclooxygenase-2 inhibitor, in human plasma using HPLC-MS/MS

A method for the simultaneous determination of etoricoxib and its carbon-13 analog ((13)C(6)-etoricoxib) from human plasma has been developed and used to support bioavailability studies. Plasma samples (0.5 mL) were extracted by using a 3M Empore 96-well plate (C(8)) and the resulting extracts were analyzed by using a PE-Sciex API-3000 HPLC-MS/MS with a heated nebulizer interface (500 degrees C). The method was validated with two different calibration curve ranges, one for etoricoxib (5 to 2500 ng/mL) determined in the presence of lower concentrations of (13)C(6)-etoricoxib (0.5 to 250 ng/mL), and a second curve for the quantitation of similar concentrations of both etoricoxib and (13)C(6)-etoricoxib (0.5 to 250 ng/mL). Extraction recoveries of etoricoxib, (13)C(6)-etoricoxib, and a methylated internal standard were >70% over the range of concentrations included in both calibration curves. Intraday precision and accuracy for the quantitation of etoricoxib were 7.8% relative standard deviation (RSD) or less and within 3.4% respectively over the range of 5 to 2500 ng/mL, and 10.8% RSD or less and within 4 % respectively over the range of 0.5 to 250 ng/mL. Within-batch precision and accuracy for the quantitation of (13)C(6)-etoricoxib over the range of 0.5 to 250 ng/mL were 8.3% RSD or less and within 2.3%, respectively. The validated assay was used in support of human clinical trials.     

Efficient radiological assessment of the internal snapping hip syndrome

The aim of this study was to evaluate the diagnostic value/significance of various imaging techniques for demonstrating the underlying causative pathology of clinically suspected internal snapping hip syndrome. We intended to define the most efficient diagnostic imaging algorithm that leads to a specific definite therapy for this rare hip disorder. The imaging studies of 54 patients (43 women, 11 men, average age 58 years) with the clinical suspicion of internal snapping hip syndrome were compared for their diagnostic value/significance for finding the underlying pathology. Radiological workup included plain radiographs of the pelvis and hip joints (n=54), ultrasound (US) of the hip joints (n=29), computed tomography (CT) of the pelvis and proximal femur (n=17), and magnetic resonance imaging (MRI) of the pelvis/hip joint (n=21). In order to establish an efficient diagnostic algorithm we compared the diagnostic value of each imaging technique alone and in combination with the other methods. The underlying causative pathology could be established in 37% of patients (n=20) by the use of conventional radiographs alone and in 46% of the patients (n=25) by US alone, and in combination in 83% of the patients (n=45). By adding CT to the radiological workup, we established final diagnosis in 88% (in combination with X-ray; n=15/17) and 94% (together with X-ray and US; n=16/17) of the patients. Whenever MR imaging was used a causative pathology was found in all patients (100%; n=21). The most efficient radiological algorithm in the assessment of patients with internal snapping hip syndrome is the combination of plain radiography and US. MR imaging can be retained for unresolved and difficult cases.     

High-throughput simultaneous determination of the HIV protease inhibitors indinavir and L-756423 in human plasma using semi-automated 96-well solid phase extraction and LC-MS/MS

A method for the simultaneous determination of the HIV protease inhibitors indinavir and L-756423, in human plasma has been developed. Plasma samples (0.5 ml) were extracted using a 3M Empore 96-well plate in the mixed phase cation exchange (MPC) format. The extraction method was automated through the application of both the Packard 204DT and TOMTEC Quadra 96 work stations, and the resulting extracts were analyzed using a PE-Sciex API-3000 LC-MS/MS with a heated nebulizer interface (500 degrees C). The assay was linear in the concentration range 1-2500 ng/ml for indinavir and 5 2500 ng/ml for L-756423 when 0.5-ml aliquots of plasma were extracted. Recoveries of indinavir and L-756423 were greater than 76 and 80%, respectively, over the calibration curve range when using the described sample preparation method. Within-batch precision and accuracy for the quantitation of indinavir over the range 1-2500 ng/ml were 5.4% R.S.D. or less and within 4.0%, respectively. Within-batch precision and accuracy for the quantitation of L-756423 over the range 5-2500 ng/ml were 5.3% R.S.D. or less and within 3.4%, respectively. Interbatch variability for the analysis of indinavir QC samples at low (3 ng/ml), middle (250 ng/ml) and high (2250 ng/ml) were 3.2, 2.9, and 1.9%, respectively. Interbatch variability for the analysis of L-756423 QC samples at low (15 ng/ml), middle (250 ng/ml) and high (2250 ng/ml) concentration were 2.0, 2.5, and 3.3%, respectively. The validated assay was used in support of human clinical trials.     

3.0 T vs. 1.5 T MR angiography: in vitro comparison of intravascular stent artifacts

PURPOSE: To evaluate the signal characteristics of different iliac artery stents in MR angiography (MRA) at 3 T in comparison with 1.5 T. MATERIALS AND METHODS: Sixteen iliac artery stents were implanted in plastic tubes filled with a solution of Gd-DTPA and imaged at 3 T and 1.5 T using a T1-weighted 3D spoiled gradient-echo sequence. Image analysis included a subjective assessment of artifact characteristics, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements in stented and unstented vessel parts, and quantitative measurements of total artifact size. RESULTS: The pattern of stent artifacts inside the stents evidently did not differ at 3 T and 1.5 T. The average total size of the artifact areas surrounding the stents was significantly larger at 3 T (P < 0.03). However, within the stented part of the vessel phantom, the signal of the lumen and its contrast to modeled surrounding tissue was significantly higher at the higher field. The mean SNR of the lumen increased from 95.5 at 1.5 T to 127.3 at 3 T, and the CNR of the vessel increased from 70.3 to 93. CONCLUSION: Assessment of the stent lumen in iliac artery stents in a phantom model is not compromised by imaging at 3 T compared to 1.5 T. The signal gain inside the stented part of the vessel lumen at higher field compensates for the higher degree of stent artifacts seen in stents made of steel or cobalt.     

Determination of an endothelin receptor antagonist in rat plasma by radioimmunoassay

A quantitative method based on radioimmunoassay for the determination of an endothelin receptor antagonist (C(31)H(33)NO(7), I) has been developed and validated. The immunogen was prepared by coupling I to the bovine serum albumin via the N-hydroxysuccinimide ester of I from which the radioligand was also prepared by the reaction with [125I]-iodotyrosine. The method was specific and no immunoactive material other than the parent drug was detectable in mammalian plasma. This direct assay, using 50 microl of rat plasma is sensitive (0.4 ng/ml), without matrix interference, and has sufficient sensitivity, specificity, accuracy and precision for the analysis of dosed rat plasma samples.     

Determination of fexofenadine in human plasma using 96-well solid phase extraction and HPLC with tandem mass spectrometric detection

A fast and sensitive HPLC-MS/MS method, utilizing atmospheric pressure chemical ionization, for the determination of fexofenadine in human plasma is described. A deuterated analog, d6-fexofenadine is used as the internal standard (IS). Plasma samples are prepared using 96-well solid phase extraction with plates containing Waters Oasis HLB sorbent. The analytes are chromatographed on a Restek Ultra IBD column (3.2 mm x 50 mm, 3 microm) using a mobile phase consisting of a mixture of 90% acetonitrile and 10% 10 mM ammonium acetate buffer and 0.1% formic acid. Quantitation of the analyte is based on the response from the multiple reaction monitoring of the precursor to product ion pairs for fexofenadine (m/z 502 --> 466) and d6-fexofenadine (m/z 508 --> 472). The assay has been validated over the concentration range of 1-200 ng/ml based on the analysis of 0.5 ml aliquots of plasma. Within-day assay accuracy was between 97 and 102% of nominal, while within-day precision was better than 3.5% CV at all points on the standard curve. Analyte extraction recovery was better than 70% over the range of the standard curve. The method was found to be suitable for the analysis of human plasma samples obtained 24 h following the administration of a single 60 mg dose of fexofenadine.     

Robotic inhibition assay for determination of HMG-CoA reductase inhibitors in human plasma

The cholesterol-lowering drug simvastatin (SIMV, Zocor reduced heart attacks by 42% in patients who had high cholesterol levels and suffered from heart disease. Upon oral administration, SIMV is quickly hydrolyzed to its beta-hydroxyacid and other acid metabolites, which are potent inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase. A Tecan-based enzyme inhibition assay has been developed to improve the existing Zymark-based assay for the determination of both active and total concentrations of HMG-CoA reductase inhibitors in human plasma. A Tecan Genesis 200 robotic workstation equipped with eight probes and customized hardware was utilized to achieve higher sample throughput and improve assay reproducibility and mechanical stability. The developed enzyme inhibition assay was validated over two concentration ranges of 0.4-20 ng equivalent/mL, and 2-50 ng equivalent/mL. Intra- and interday precision data (coefficient of variation (CV)) for both concentration ranges were less than 9%, with an accuracy of 93-107%. The interday precision for the determination of quality control (QC) samples was less than 2% and 8%, respectively. The respective interday QC accuracy values were 93-103% and 97-104%. Good linearity across the two concentration ranges was observed, with acceptable reproducibility. This improved enzyme inhibition assay has been utilized to analyze human plasma samples from several clinical studies.