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Excellent Reproducibility (excellent + reproducibility)
Selected AbstractsAmperometric L -Lactate Biosensor Based on Gold NanoparticlesELECTROANALYSIS, Issue 7-8 2007Bikash, Kumar Jena Abstract A novel amperometric biosensor for the sensing of L -lactate is developed using L -lactate dehydrogenase (LDH) and hydroxylamine enlarged gold nanoparticles (GNPs). LDH and GNPs have been integrated with the sol,gel 3-D silicate network derived from 3-(mercaptopropyl)trimethoxysilane (MPTS). The biosensing of L -lactate is based on the electrocatalytic determination of enzymatically generated NADH by GNPs of the integrated assembly. The GNPs on the network efficiently catalyze the oxidation of NADH at ,0.065,V, which is ca. 915,mV less positive than on the bulk Au electrode. The biosensor was characterized in terms of the effects of enzyme loading, solution pH, and cofactor concentration. The integrated biosensor was successfully utilized for the amperometric sensing of L -lactate and it shows excellent sensitivity with a detection limit of 100,nM. The common interfering electroactive compounds in the biological system do not interfere the amperometric measurement of L -lactate. This biosensor linearly responds to L -lactate in the range of 0,0.8,mM and the sensitivity of the electrode was 0.446,nA/nM. Excellent reproducibility, long time storage and operational stability have been achieved. [source] Development and application of the human intestinal tract chip, a phylogenetic microarray: analysis of universally conserved phylotypes in the abundant microbiota of young and elderly adultsENVIRONMENTAL MICROBIOLOGY, Issue 7 2009-Stojanovi, Mirjana Rajili Summary In this paper we present the in silico assessment of the diversity of variable regions of the small subunit ribosomal RNA (SSU rRNA) gene based on an ecosystem-specific curated database, describe a probe design procedure based on two hypervariable regions with minimal redundancy and test the potential of such probe design strategy for the design of a flexible microarray platform. This resulted in the development and application of a phylogenetic microarray for studying the human gastrointestinal microbiota , referred as the human intestinal tract chip (HITChip). Over 4800 dedicated tiling oligonucleotide probes were designed based on two hypervariable regions of the SSU rRNA gene of 1140 unique microbial phylotypes (< 98% identity) following analysis of over 16 000 human intestinal SSU rRNA sequences. These HITChip probes were hybridized to a diverse set of human intestinal samples and SSU rRNA clones to validate its fingerprinting and quantification potential. Excellent reproducibility (median Pearson's correlation of 0.99) was obtained following hybridization with T7 polymerase transcripts generated in vitro from SSU rRNA gene amplicons. A linear dose,response was observed with artificial mixtures of 40 different representative amplicons with relative abundances as low as 0.1% of total microbiota. Analysis of three consecutively collected faecal samples from ten individuals (five young and five elderly adults) revealed temporal dynamics and confirmed that the adult intestinal microbiota is an individual-specific and relatively stable ecosystem. Further analysis of the stable part allowed for the identification of a universal microbiota core at the approximate genus level (90% sequence similarity). This core consists of members of Actinobacteria, Bacteroidetes and Firmicutes. Used as a phylogenetic fingerprinting tool with the possibility for relative quantification, the HITChip has the potential to bridge the gaps in our knowledge in the quantitative and qualitative description of the human gastrointestinal microbiota composition. [source] Protein separations using polyelectrolyte multilayer coatings with molecular micelles in open tubular capillary electrochromatographyELECTROPHORESIS, Issue 4 2008Candace A. Luces Abstract Novel polyelectrolyte multilayer (PEM) coatings for enhanced protein separations in open tubular CEC (OT-CEC) are reported. Use of four cationic polymers (poly- L -lysine, poly- L -ornithine, poly- L -lysine-serine, and poly- L -glutamic acid-lysine), and three anionic molecular micelles, sodium poly(N -undecanoyl- L -leucyl-alaninate) (poly- L -SULA), sodium poly(N -undecanoyl- L -leucyl-valinate) (poly- L -SULV), and sodium poly(undecylenic sulfate) (poly-SUS) were investigated in PEM coatings for protein separations. The simultaneous effects of cationic polymer concentration, number of bilayers, temperature, applied voltage, and pH of the BGE on the separation of four basic proteins (,-chymotrypsinogen A, lysozyme, ribonuclease A, and cytochrome c) were analyzed using a Box Behnken experimental design. The influence of NaCl on the run-to-run reproducibility was investigated for PEM coatings containing each cationic polymer. All coatings exhibited excellent reproducibilities with a %RSD of the EOF less than 1% in the presence of NaCl. Optimal conditions were dependent on both the cationic and anionic polymers used in the PEM coatings. Poly- L -glutamic acid-lysine produced the highest resolution and longest migration time. The use of molecular micelles to form PEM coatings resulted in better separations than single cationic coatings. Chiral poly- L -SULA and poly- L -SULV resulted in higher protein resolutions as compared to the achiral, poly-SUS. Furthermore, the use of poly- L -SULV reversed the elution order of lysozyme and cytochrome c when compared to poly- L -SULA and poly-SUS. [source] Amplitude and Velocity of Mitral Annulus Motion in RabbitsECHOCARDIOGRAPHY, Issue 4 2004Li-ming Gan M.D., Ph.D. Objective: During recent years, the amplitude and the maximal systolic velocity of the mitral annulus motion (MAM) have been established as indices of the left ventricular systolic function and the maximal diastolic velocity of the annulus motion has been suggested as an index of diastolic function. The main aims of the present study were to investigate the feasibility of these techniques in rabbits and to investigate age-related changes concerning these variables. Methods: Twenty-one New Zealand white rabbits were investigated by echocardiographic M-mode and pulsed tissue Doppler. One subgroup (I) included 11 still-growing, 3.0 ± 0.2 month-old, animals and another group (II) included 10 young grown up rabbits, 12.1 ± 1.5 months old. Results: The amplitude (4.8 ± 0.6 and 3.5 ± 0.3 mm, respectively) and maximal systolic (98 ± 14 and 66 ± 7 mm/s, respectively) and diastolic (111 ± 21 and 80 ± 12 mm/s, respectively) velocities of the MAM were significantly (P < 0.001) higher in group I than in group II, despite a bigger heart in the animals in the latter group. A coefficient of variation of <5% was found for both inter- and intraobserver variability for both amplitude and velocities. Conclusions: The amplitude and velocities of MAM are easily recorded in rabbits with excellent reproducibility and the changes with age seem to be very similar to those in humans. These noninvasive M-mode and tissue Doppler methods are therefore suitable for the investigation of left ventricular function in experimental studies in rabbits. (ECHOCARDIOGRAPHY, Volume 21, May 2004) [source] Lable-Free Electrochemical DNA Sensor Based on Gold Nanoparticles/Poly(neutral red) Modified ElectrodeELECTROANALYSIS, Issue 6 2010Keying Zhang Abstract We present a new strategy for the label-free electrochemical detection of DNA hybridization based on gold nanoparticles (AuNPs)/poly(neutral red) (PNR) modified electrode. Probe oligonucledotides with thiol groups at the 5-end were covalently linked onto the surface of AuNPs/PNR modified electrode via S-Au binding. The hybridization event was monitored by using differential pulse voltammetry (DPV) upon hybridization generates electrochemical changes at the PNR-solution interface. A significant decrease in the peak current was observed upon hybridization of probe with complementary target ssDNA, whereas no obvious change was observed with noncomplementary target ssDNA. And the DNA sensor also showed a high selectivity for detecting one-mismatched and three-mismatched target ssDNA and a high sensitivity for detecting complementary target ssDNA, the detection limit is 4.2×10,12,M for complementary target ssDNA. In addition, the DNA biosensor showed an excellent reproducibility and stability under the DNA-hybridization conditions. [source] Simultaneous Determination of Dopamine and Ascorbic Acid Using the Nano-Gold Self-Assembled Glassy Carbon ElectrodeELECTROANALYSIS, Issue 10 2009Guangzhi Hu Abstract Electrochemical behavior of dopamine (DA) was investigated at the gold nanoparticles self-assembled glassy carbon electrode (GNP/LC/GCE), which was fabricated by self-assembling gold nanoparticles on the surface of L -cysteine (LC) modified glassy carbon electrode (GCE) via successive cyclic voltammetry (CV). A pair of well-defined redox peaks of DA on the GNP/LC/GCE was obtained at Epa=0.197,V and Epc=0.146,V, respectively. And the peak separation between DA and AA is about 0.2,V, which is enough for simultaneous determination of DA and AA. The peak currents of DA and AA were proportional with their concentrations in the range of 6.0×10,8,8.5×10,5 mol L,1 and 1.0×10,6,2.5×10,3 mol L,1, with the detection limit of 2.0×10,8 mol L,1 and 3.0×10,7 mol L,1 (S/N=3), respectively. The modified electrode exhibits an excellent reproducibility, sensibility and stability for simultaneous determination of DA and AA in human serum with satisfactory result. [source] Comparison of two glutaraldehyde immobilization techniques for solid-phase tryptic peptide mapping of human hemoglobin by capillary zone electrophoresis and mass spectrometryELECTROPHORESIS, Issue 9 2004Isabelle Migneault Abstract Stabilization of proteolytic enzymes, especially by immobilization, is of considerable interest because of their potential applications in medicine and the chemical and pharmaceutical industries. We report here a detailed comparison of two procedures for trypsin immobilization using the same homobifunctional agent, glutaraldehyde, for the purpose of peptide mapping. These methods include covalent coupling either to controlled pore glass (solid support) or via a cross-linking reaction (without any solid support). The immobilized trypsin preparations were characterized by the determination of immobilization efficiency, which ranged from 68 to > 95%, and measurement of apparent kinetic parameters toward a synthetic peptide-like substrate. Batch digestions of whole denaturated human normal adult hemoglobin (HbA) were performed to obtain peptide maps by capillary zone electrophoresis (CZE). Migration time reproducibility of the CZE maps was excellent, with a mean relative standard deviation of 1.5%. Moreover, the two immobilized enzyme preparations showed excellent reproducibility for repeated digestions. Matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry was also used for peptide mass mapping of denaturated HbA digested using the two immobilized trypsin preparations. Even though the two immobilized trypsin preparations do not behave identically, similar sequence coverages of 57% and 61% (for the two HbA chains merged) were achieved for the support-based and cross-linked trypsin preparations, respectively. [source] Cardiac and coronary function in the Langendorff-perfused mouse heart modelEXPERIMENTAL PHYSIOLOGY, Issue 1 2009Melissa E. Reichelt The Langendorff mouse heart model is widely employed in studies of myocardial function and responses to injury (e.g. ischaemia). Nonetheless, marked variability exists in its preparation and functional properties. We examined the impact of early growth (8, 16, 20 and 24 weeks), sex, perfusion fluid [Ca2+] and pacing rate on contractile function and responses to 20 min ischaemia followed by 45 min reperfusion. We also assessed the impact of strain, and tested the utility of the model in studying coronary function. Under normoxic conditions, hearts from 8-week-old male C57BL/6 mice (2 mm free perfusate [Ca2+], 420 beats min,1) exhibited 145 ± 2 mmHg left ventricular developed pressure (LVDP). Force development declined by ,15% (126 ± 5 mmHg) with a reduction in free [Ca2+] to 1.35 mm, and by 25% (108 ± 3 mmHg) with increased pacing to 600 beats min,1. While elevated heart rate failed to modify ischaemic outcome, the lower [Ca2+] significantly improved contractile recovery (by >30%). We detected minimal sex-dependent differences in normoxic function between 8 and 24 weeks, although age modified contractile function in males (increased LVDP at 24 versus 8 weeks) but not females. Both male and female hearts exhibited age-related reductions in ischaemic tolerance, with a significant decline in recovery evident at 16 weeks in males and later, at 20,24 weeks, in females (versus recoveries in hearts at 8 weeks). Strain also modified tolerance to ischaemia, with similar responses in hearts from C57BL/6, 129/sv, Quackenbush Swiss and FVBN mice, but substantially greater tolerance in BALB/c hearts. In terms of vascular function, baseline coronary flow (20,25 ml min,1 g,1) was 50,60% of maximally dilated flows, and coronary reactive and functional hyperaemic responses were pronounced (up to 4-fold elevations in flow in hearts lacking ventricular balloons). These data indicate that attention to age (and sex) of mice will reduce variability in contractile function and ischaemic responses. Even small differences in perfusion fluid [Ca2+] also significantly modify tolerance to ischaemia (whereas modest shifts in heart rate do not impact). Ischaemic responses are additionally strain dependent, with BALB/c hearts displaying greatest intrinsic tolerance. Finally, the model is applicable to the study of vascular reactivity, providing large responses and excellent reproducibility. [source] Fractal dimension can distinguish models and pharmacologic changes in liver fibrosis in ratsHEPATOLOGY, Issue 4 2002Frédéric Moal Fractal analysis measures the complexity of geometric structures. The aim of this study was to evaluate the feasibility and accuracy of fractal analysis in liver fibrosis. A total of 77 rats were included: 10 sham, 46 with fibrosis secondary to bile duct ligation (BDL), and 21 with fibrosis due to CCl4 intoxication. Measurements included the fractal dimension of Kolmogorov (Dk), histologic lesions, the area of fibrosis by image analysis, liver hydroxyproline content, messenger RNA fibronectin, serum hyaluronate level, and portal pressure. Fibrotic rats were given placebo, octreotide, or O2 -vinyl 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (V-PYRRO/NO). Intraobserver agreement of Dk was excellent with the intraclass (ic) correlation coefficient ric = 0.91 (P < .0001) as well as the interobserver agreement with ric = 0.88 (P < .001). Dk was correlated with other measurements or markers of fibrosis: the area of fibrosis (r = 0.75; P < .0001), hydroxyproline content (r = 0.51; P < .001), serum hyaluronate level (r = 0.52; P < .001), and portal pressure (r = 0.52; P < .01). Dk was significantly different between the 2 models of fibrosis (P < .0001), unlike the area of fibrosis, and this relationship was independent of other histologic lesions. The significant decrease in fibrosis observed with octreotide or V-PYRRO/NO was similarly reflected by Dk or the area of fibrosis. The diagnostic accuracy for the fibrosis model was 97% with the 5 main measurements or markers of fibrosis studied, with Dk isolated at the first step by stepwise analysis. In conclusion, fractal analysis is suitable for analyzing liver fibrosis and has excellent reproducibility. This is the only quantitative morphometric method that can discriminate among the models of fibrosis and is sensitive enough to detect pharmacologically induced changes in liver fibrosis. [source] Parallel imaging of knee cartilage at 3 TeslaJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2007Jin Zuo PhD Abstract Purpose To evaluate the feasibility and reproducibility of quantitative cartilage imaging with parallel imaging at 3T and to determine the impact of the acceleration factor (AF) on morphological and relaxation measurements. Materials and Methods An eight-channel phased-array knee coil was employed for conventional and parallel imaging on a 3T scanner. The imaging protocol consisted of a T2-weighted fast spin echo (FSE), a 3D-spoiled gradient echo (SPGR), a custom 3D-SPGR T1rho, and a 3D-SPGR T2 sequence. Parallel imaging was performed with an array spatial sensitivity technique (ASSET). The left knees of six healthy volunteers were scanned with both conventional and parallel imaging (AF = 2). Results Morphological parameters and relaxation maps from parallel imaging methods (AF = 2) showed comparable results with conventional method. The intraclass correlation coefficient (ICC) of the two methods for cartilage volume, mean cartilage thickness, T1rho, and T2 were 0.999, 0.977, 0.964, and 0.969, respectively, while demonstrating excellent reproducibility. No significant measurement differences were found when AF reached 3 despite the low signal-to-noise ratio (SNR). Conclusion The study demonstrated that parallel imaging can be applied to current knee cartilage quantification at AF = 2 without degrading measurement accuracy with good reproducibility while effectively reducing scan time. Shorter imaging times can be achieved with higher AF at the cost of SNR. J. Magn. Reson. Imaging 2007;26:1001,1009. © 2007 Wiley-Liss, Inc. [source] Visible light initiated polymerization of styrenic monolithic stationary phases using 470,nm light emitting diode arraysJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2010Zarah Walsh Abstract Poly(styrene- co -divinylbenzene) monolithic stationary phases have been synthesized for the first time by photoinitiated polymerization. An initiator composed of (+)-(S)-camphorquinone/ethyl-4-dimethylaminobenzoate/N- methoxy-4-phenylpyridinium tetrafluoroborate was activated using a 470,nm light emitting diode array as the light source. Spatially controlled polymerization of styrenic monoliths has been achieved within specific sections of a 100,,m id polytetrafluoroethylene-coated fused-silica capillary using simple photo masking. The sharpness of the edges was confirmed by optical microscopy, while SEM was used to verify a typical porous, globular morphology. Flow resistance data were used to assess the permeability of the monoliths and they were found to have good flow through properties with a flow resistance of 0.725,MPa/cm at 1,,L/min (water, 20°C). Conductivity profiling along the length of the capillary was used to assess their lateral homogeneity. Monoliths which were axially rotated during polymerization were found to be homogeneous along the whole length of the capillary. The monolithic stationary phases were applied to the RP gradient separation of a mixture of proteins. Column fabrication showed excellent reproducibility with the retention factor (k) having a RSD value of 2.6% for the batch and less than 1.73% on individual columns. [source] Measurement of abdominal symptoms by validated questionnaire: a 3-month recall timeframe as recommended by Rome III is not superior to a 1-year recall timeframeALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 11 2010E. REY Aliment Pharmacol Ther,31, 1237,1247 Summary Background, Rome III incorporates changes in the definition of functional gastrointestinal disorder that involve a 3-month recall time for symptoms, rather than 1-year. Aim, To validate a new version of the Talley-Bowel Disease Questionnaire (Talley-BDQ) and assess the impact of recall time period on the prevalence of symptoms. Methods, A sample of community residents were randomly mailed a survey using 1-year (n = 396) or 3-month recall period (n = 374). We evaluated the reliability and the concurrent validity of the two versions of the questionnaire. The proportions of subjects reporting symptoms in the two versions were compared. Results, The median (IQR) kappa on symptom-related questions was 0.70 (0.57,0.76) from the 1-year version and 0.66 (0.56,0.77) from the 3-month version. A median kappa of 0.39 (0.19,0.70) and 0.58 (0.39,0.73) was observed for concurrent validation of the 1-year and 3-month versions respectively. Except for gastro-oesophageal reflux symptoms, no differences were observed on the prevalence of clinically relevant symptoms. Conclusion, The revised Talley-BDQ is reliable, with excellent reproducibility and validity. There were few differences in reported symptom rates between the 3-month and 1-year recall time versions of the questionnaire. A 1-year recall time may more efficiently capture infrequent or subtle symptoms. [source] Determination of ibuprofen in pharmaceutical formulations using time-resolved terbium-sensitized luminescenceLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 4 2007Salma M. Z. Al-Kindy Abstract A sensitive and specific luminescence method for the determination of ibuprofen (IB) in pharmaceutical formulations in aqueous solution is described. The method is based on the luminescence sensitization of terbium (Tb3+) by formation of ternary complex with IB in the presence of tri- n -octylphosphine oxide (TOPO) and Tween-20 as surfactant. The luminescence signal for Tb,IB,TOPO is monitored at ,ex = 229 nm and ,em = 545 nm. Optimum conditions for the formation of the complex in aqueous system, were 16 mmol/L TRIS buffer, pH 5.7, TOPO 200 µmol/L and 15 µmol/L of Tb3+, which allows for the determination of 9.7 × 10,7 , 9.7 × 10,6 mol/L IB with a detection limit of 1.2 × 10,7 mol/L. The relative standard deviations of the method were <1.4%, indicating excellent reproducibility. The proposed method was successfully applied for the assays of IB in pharmaceutical formulations with average recoveries of 100.3,102.5%. Copyright © 2007 John Wiley & Sons, Ltd. [source] Rapid 3D-T1, mapping of the knee joint at 3.0T with parallel imagingMAGNETIC RESONANCE IN MEDICINE, Issue 3 2006S. Kubilay Pakin Abstract Three-dimensional spin-lattice relaxation time in the rotating frame (3D-T1,) with parallel imaging at 3.0T was implemented on a whole-body clinical scanner. A 3D gradient-echo sequence with a self-compensating spin-lock pulse cluster was combined with generalized autocalibrating partially parallel acquisitions (GRAPPA) to acquire T1, -weighted images. 3D-T1, maps of an agarose phantom and three healthy subjects were constructed using an eight-channel phased-array coil without parallel imaging and with parallel imaging acceleration factors of 2 and 3, in order to assess the reproducibility of the method. The coefficient of variation (CV) of the median T1, of the agarose phantom was 0.44%, which shows excellent reproducibility. The reproducibility of in vivo 3D-T1, maps was also investigated in three healthy subjects. The CV of the median T1, of the patellar cartilage varied between ,1.1% and 4.3%. Similarly, the CV varied between ,2.1,5.8%, ,1.4,8.7%, and ,1.5,4.1% for the biceps femoris and lateral and medial gastrocnemius muscles, respectively. The preliminary results demonstrate that 3D-T1, maps can be constructed with good reproducibility using parallel imaging. 3D-T1, with parallel imaging capability is an important clinical tool for reducing both the total acquisition time and RF energy deposition at 3T. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] Molecular typing of Aspergillus speciesMYCOSES, Issue 6 2008H. A. De Valk Summary Aspergillus species are widely distributed fungi that release large amounts of airborne conidia, which are dispersed in the environment. Several Aspergillus species have been described as human pathogens. Molecular techniques have been developed to investigate the epidemiological relation between environmental and clinical isolates. Several typing methods have been described for Aspergillus species, most of them with reference to Aspergillus fumigatus. Here, we summarise all the different available molecular typing techniques for Aspergillus. The performance of these techniques is evaluated with respect to their practical feasibility, and their interpretation and discriminatory power assessed. For A. fumigatus isolates, a large extent of genetic variability is demonstrated and therefore fingerprinting techniques with high discriminatory power and high reproducibility are required for this species. Afut1-restriction fragment length polymorphism and microsatellite typing showed the highest discriminatory power. In addition, the microsatellites show excellent reproducibility. Other typing techniques are still useful for smaller epidemiological problems and for less well-equipped laboratories. [source] Utility of porous graphitic carbon stationary phase in quantitative liquid chromatography/tandem mass spectrometry bioanalysis: quantitation of diastereomers in plasmaRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2006Yuan-Qing Xia A major challenge in selecting an appropriate stationary phase for diastereomeric separation is that it is difficult to predict which of the commercially available stationary phases could achieve the required liquid chromatographic (LC) separation. This work describes the selection and evaluation of a porous graphitic carbon (PGC) column coupled with tandem mass spectrometry (MS/MS) for the simultaneous quantitation of an experimental drug candidate (I), its two diastereomeric metabolites (II and III), and its demethylated metabolite (IV) in rat plasma. In addition, we investigated the PGC column for the separation of another drug candidate (VI), its two diastereomeric metabolites (VII and VIII) and its ketone metabolite (IX). The PGC column showed excellent chromatographic resolution for the two diastereomers II and III, as well as for VII and VIII. In contrast, the required resolution for the diastereomers II and III could not be achieved using silica-bonded C18, C30, phenyl, perfluorinated, polar embedded and polar end-capped phases. The PGC column showed ruggedness with excellent reproducibility of retention times, peak symmetry and response over a period of more than 400 injections of a plasma acetonitrile-precipitation extract. Excellent accuracy and precision were achieved, with accuracy of 94,108% and intra- and inter-run precision within 9%. This work indicates that PGC is a valuable addition to the repertoire of LC columns used for quantitative LC/MS/MS bioanalysis, especially where the separation and quantitation of diastereomeric analytes is involved. Copyright © 2006 John Wiley & Sons, Ltd. [source] Two Temporal Bone Computed Tomography Measurements Increase Recognition of Malformations and Predict Sensorineural Hearing Loss,THE LARYNGOSCOPE, Issue 8 2006Derk D. Purcell MD Abstract Objectives/Hypothesis: The objectives of this prospective study were to assess the reproducibility of the measurements of the cochlea and lateral semicircular canal (LSCC) and to determine if abnormal measurements predict sensorineural hearing loss (SNHL). Methods: Two readers independently measured the cochlear height on coronal section and the LSCC bony island width on axial section on 109 temporal bone computed tomography scans; audiologic data on these patients were collected independently from medical records. Inter- and intrareader variability was evaluated using intraclass correlation coefficients (ICCs) based on a random-effects model. The positive and negative predictive values of abnormal measurement for hearing loss were determined. Results: There was excellent inter- and intraobserver agreement for both measurements (ICC >80%). The average cochlear height was 5.1 mm (normal range, 4.4,5.9 mm) and average LSCC bony island width was 3.7 mm (normal range, 2.6,4.8 mm). Review of the original radiology reports demonstrated that both cochlear hypoplasia and LSSC dysplasia were overlooked in >50% of patients with both abnormal measurements and SNHL. Cochlear hypoplasia (<4.4 mm) had a positive predictive value of 100% for SNHL, whereas cochlear hyperplasia and bony island dysplasia were less predictive. Conclusion: The measurements of coronal cochlear height and axial LSCC bony width have excellent reproducibility and identify bony labyrinth abnormalities missed by visual inspection alone. In addition, cochlear hypoplasia is highly predictive of SNHL. To reliably identify inner ear malformations, measurement of the cochlear height and LSCC bony island width, in addition to the vestibular aqueduct, should be routinely performed on all temporal bone studies. [source] High-performance liquid chromatographic method for simple and rapid determination of linezolid in human plasmaBIOMEDICAL CHROMATOGRAPHY, Issue 8 2006Lauren M. Boak Abstract A simple high-performance liquid chromatographic (HPLC) method was developed and validated for rapid quantification of linezolid in human plasma. Protein precipitation using a mixture of 5% trichloroacetic acid and methanol (3:1, v/v) provided a straightforward method of sample preparation and the internal standard eperezolid was employed. A concentration range from 0.20 to 40.0 mg/L was utilized to construct calibration curves, and analysis of low- (0.40 mg/L), medium- (7.50 mg/L) and high-quality (25.0 mg/L) control samples revealed excellent reproducibility (,3.88%) and accuracy (,4.20%). The recovery of both linezolid and eperezolid was approximately 100%. No interference was observed at the retention times of linezolid and eperezolid from blank plasma or eight commonly used antibiotics. Tests confirmed the stability of linezolid in plasma during three freeze,thaw cycles, on the bench during 24 h and during long-term storage of frozen plasma for up to 12 weeks; in extracts it was stable in the HPLC autosampler over 12 h. Overall, this assay offers a highly simplistic approach to quantifying linezolid in plasma, and would be well suited to clinical pharmacokinetic, pharmacodynamic and toxicodynamic analyses. Copyright © 2005 John Wiley & Sons, Ltd. [source] A New Amperometric Biosensor Based on HRP/Nano-Au/L -Cysteine/Poly(o -Aminobenzoic acid)-Membrane-Modified Platinum Electrode for the Determination of Hydrogen PeroxideCHINESE JOURNAL OF CHEMISTRY, Issue 11 2006Ming-Yu Tang Abstract The third generation amperometric biosensor for the determination of hydrogen peroxide (H2O2) has been described. For the fabrication of biosensor, o -aminobenzoic acid (oABA) was first electropolymerized on the surface of platinum (Pt) electrode as an electrostatic repulsion layer to reject interferences. Horseradish peroxidase (HRP) absorbed by nano-scaled particulate gold (nano-Au) was immobilized on the electrode modified with polymerized o -aminobenzoic acid (poABA) with L -cysteine as a linker to prepare a biosensor for the detection of H2O2. Amperometric detection of H2O2 was realized at a potential of +20 mV versus SCE. The resulting biosensor exhibited fast response, excellent reproducibility and sensibility, expanded linear range and low interferences. Temperature and pH dependence and stability of the sensor were investigated. The optimal sensor gave a linear response in the range of 2.99×10,6 to 3.55×10,3 mol·L,1 to H2O2 with a sensibility of 0.0177 A·L,1·mol,1 and a detection limit (S/N=3) of 4.3×10,7 mol·L,1. The biosensor demonstrated a 95% response within less than 10 s. [source] Inorganic-Organic Hybrid 18-Molybdodiphosphate Nanoparticles Bulk-modified Carbon Paste Electrode and Its ElectrocatalysisCHINESE JOURNAL OF CHEMISTRY, Issue 8 2002Xiu-Li Wang Abstract A kind of inorganic-organic hybrid 18-molybdodiphosphate nanoparticles ([(C4H9)4N]6P2Mo18Q62·4H2O) was firstly used as a bulk-modifier to fabricate a three-dimensional chemically modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior of the solid nanoparticles dispersed in the CPE in acidic aqueous solution was characterized by cyclic and square-wave voltammetry. The hybrid 18-molybdodiphosphate nanoparticles bulk-modified CPE (MNP-CPE) displayed a high electrocatalytic activity towards the reduction of nitrite, bromate and hydrogen peroxide. The remarkable advantages of the MNP-CPE over the traditional polyoxometalates-modified electrodes are their excellent reproducibility of surface-renewal and high stability owing to the insolubility of the hybrid 18-molybdodiphosphate nanoparticles. [source] | ||||||||||||||||