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[The effect of terguride on the dynamics and mean level of vigilance. A controlled electroencephalographic study with elderly subjects].

The influence of a 3-week medication period with terguride (trans-dihydro-lisuride) in a dosage of 2 X 0.2 mg/d per os upon the 10-min resting EEG of elderly, clinically normal volunteers (mean age 70 years was investigated. Eight subjects received placebo and 7 subjects received terguride under double-blind conditions. The EEG data were analysed, inter alia, by a newly-developed method of quantification which uses information on topographical relationships of the absolute alpha-powers provided by two anterior and two posterior leads. Under terguride, but not under placebo, a significant increase of subvigilant patterns was found. If one were to disregard the baseline situation, which was characterized in the present sample by a distinct restriction of the physiological dynamics of vigilance at a reduced level (dynamic rigidity), this finding would have to be interpreted as sedation. A non-physiological pre-drug situation was indicated by marked and sustained anteriorization of alpha-activity. Taking into account our additional finding that terguride, but not placebo, eliminates this non-physiological alpha-anteriorization, we interpret the increase of subvigilant patterns in the course of the recording period as a resolution of the preexisting dynamic rigidity and, consequently, as a therapeutically desirable effect.

Aged↗

Development of a real-time PCR assay for rapid detection and quantification of Alexandrium minutum (a Dinoflagellate).

The marine dinoflagellate genus Alexandrium includes a number of species which produce neurotoxins responsible for paralytic shellfish poisoning (PSP), which in humans may cause muscular paralysis, neurological symptoms, and, in extreme cases, death. A. minutum is the most widespread toxic PSP species in the western Mediterranean basin. The monitoring of coastal waters for the presence of harmful algae also normally involves microscopic examinations of phytoplankton populations. These procedures are time consuming and require a great deal of taxonomic experience, thus limiting the number of specimens that can be analyzed. Because of the genetic diversity of different genera and species, molecular tools may also help to detect the presence of target microorganisms in marine field samples. In this study, we developed a real-time PCR-based assay for rapid detection of all toxic species of the Alexandrium genus in both fixative-preserved environmental samples and cultures. Moreover, we developed a real-time quantitative PCR assay for the quantification of A. minutum cells in seawater samples. Alexandrium genus-specific primers were designed on the 5.8S rDNA region. Primer specificity was confirmed by using BLAST and by amplification of a representative sample of the DNA of other dinoflagellates and diatoms. Using a standard curve constructed with a plasmid containing the ITS1-5.8S-ITS2 A. minutum sequence and cultured A. minutum cells, we determined the absolute number of 5.8S rDNA copies per cell. Consequently, after quantification of 5.8S rDNA copies in samples containing A. minutum cells, we were also able to estimate the number of cells. Several fixed A. minutum bloom sea samples from Arenys Harbor (Catalan Coast, Spain) were analyzed using this method, and quantification results were compared with standard microscopy counting methods. The two methods gave comparable results, confirming that real-time PCR could be a valid, fast alternative procedure for the detection and quantification of target phytoplankton species during coastal water monitoring.

Animals↗

Validated assay for quantification of oxcarbazepine and its active dihydro metabolite 10-hydroxycarbazepine in plasma by atmospheric pressure chemical ionization liquid chromatography/mass spectrometry.

Oxcarbazepine (OX), a new antiepileptic, may lead to unwanted side-effects or even life-threatening intoxications after overdose. Therefore, a validated liquid chromatographic/mass spectrometric (LC/MS) assay was developed for the quantification of OX and its pharmacologically active dihydro metabolite (dihydrooxcarbazepine, DOX, often named 10-hydroxycarbazepine). OX and DOX were extracted from plasma by the authors' standard liquid/liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. The compounds were quantified in the selected-ion monitoring mode using atmospheric pressure chemical ionization electrospray LC/MS. The assay was fully validated. It was found to be selective. The calibration curves were linear from 0.1 to 50 mg l(-1) for OX and DOX. Limits of quantification were 0.1 mg l(-1) for OX and DOX. The absolute recoveries were between 60 and 86%. The accuracy and precision data were within the required limits. The analytes in frozen plasma samples were stable for at least 1 month. The method was successfully applied to several authentic plasma samples from patients treated or intoxicated with OX. The measured therapeutic plasma levels ranged from 1 to 2 mg l(-1) for OX and from 10 to 40 mg l(-1) for DOX. The validated LC/MS assay proved to be appropriate for quantification of OX and DOX in plasma for clinical toxicology and therapeutic drug monitoring purposes. The assay is part of a general analysis procedure for the isolation, separation and quantification of various drugs and for their full-scan screening and identification.

Anticonvulsants↗

Direct quantification of mRNA expression levels using single molecule detection.

Determination of the gene expression by direct quantification of mRNA is becoming increasingly important in basic, pharmaceutical and clinical research. We present a novel approach for gene quantification based on direct hybridization of gene-specific probes to target mRNA sequences in solution at temperatures ensuring absolute specificity of the probe-target complex. No enzymatic steps like reverse transcription or amplification by PCR are involved within the quantification process. In order to increase specificity as well as sensitivity, two probes emitting fluorescence light in different colors are used for our homogeneous assay using fluorescence cross-correlation. We relate to the single molecule sensitivity of excitation and detection in confocal cavities avoiding the amplification of the detected signal. The analysis of the expression level of high, medium and low abundant genes is described in two different cell lines, whereby the genes are quantified in absolute numbers.

Calcium-Binding Proteins↗

Simultaneous determination of adenosine, S-adenosylhomocysteine and S-adenosylmethionine in biological samples using solid-phase extraction and high-performance liquid chromatography.

A sensitive and rapid method for measuring simultaneously adenosine, S-adenosylhomocysteine and S-adenosylmethionine in renal tissue, and for the analysis of adenosine and S-adenosylhomocysteine concentrations in the urine is presented. Separation and quantification of the nucleosides are performed following solid-phase extraction by reversed-phase ion-pair high-performance liquid chromatography with a binary gradient system. N6-Methyladenosine is used as the internal standard. This method is characterized by an absolute recovery of over 90% of the nucleosides plus the following limits of quantification: 0.25-1.0 nmol/g wet weight for renal tissue and 0.25-0.5 microM for urine. The relative recovery (corrected for internal standard) of the three nucleosides ranges between 98.1 +/- 2.6% and 102.5 +/- 4.0% for renal tissue and urine, respectively (mean +/- S.D., n = 3). Since the adenosine content in kidney tissue increases instantly after the onset of ischemia, a stop freezing technique is mandatory to observe the tissue levels of the nucleosides under normoxic conditions. The resulting tissue contents of adenosine, S-adenosylhomocysteine and S-adenosylmethionine in normoxic rat kidney are 5.64 +/- 2.2, 0.67 +/- 0.18 and 46.2 +/- 1.9 nmol/g wet weight, respectively (mean +/- S.D., n = 6). Urine concentrations of adenosine and S-adenosylhomocysteine of man and rat are in the low microM range and are negatively correlated with urine flow-rate.

Adenosine↗

High pressure liquid chromatographic analysis of the serum concentration of cefuroxime after an intravenous bolus injection of cefuroxime in patients with a coronary artery bypass grafting.

A simple reversed-phase high pressure liquid chromatographic method was developed for the determination of cefuroxime in the serum of patients undergoing coronary artery bypass grafting. The serum was cleaned up with a 3.3% solution of perchloric acid in water. Cefalexine was used as an internal standard. Detection was made by a UV multi-wavelength detector. The optimum wavelength for cefuroxime is 275 nm. The absolute recovery of this method was 90.9%; the limit of quantification was 0.7 mg/l. This analytical method was used in a study to investigate the cefuroxime serum concentration--time curves in 26 patients undergoing coronary artery bypass grafting. It was found that one single dose is sufficient to obtain effective serum concentrations.

Adult↗

Determination of desoxyepothilone B in nude mice plasma by liquid-liquid extraction and reversed-phase high-performance liquid chromatography.

A novel reversed-phase high-performance liquid chromatographic (HPLC) method has been established for the determination of a newly developed anti-cancer agent desoxyepothilone B (dEpo B) in nude mice plasma. The sample preparation involved deproteination of 200 microl of plasma sample first, followed by liquid-liquid extraction of the resultant supernatant with chloroform. The compound taxol was used as the internal standard. Chromatographic separations were carried out on a 250 mm x 4.6 mm Zorbax SB-phenyl column with acetonitrile-0.25% orthophosphoric acid (50/50, v/v) as mobile phase and UV detection at 250 nm. For dEpo B and taxol at the concentration level of 10 microg/ml in nude mice plasma, the absolute extraction recoveries were 85.3 and 87.2%, respectively. The linear quantification range of the method was 0.1-100 microg/ml in nude mice plasma with linear correlation coefficients greater than 0.999. The within-day and between-day relative standard deviations (R.S.D.s) for dEpo B at 0.5, 2.5 and 10 microg/ml levels in nude mice plasma fell in the range of 2.8-4.8 and 1.5-4.6%, and the within-day and between-day recoveries were in the range of 96.5-101.7 and 97.7-101.2%, respectively.

Animals↗

Quantification of cell surface roughness; a method for studying cell mechanical and adhesive properties.

The presence on the surface of nucleated cells of a variety of asperities of different size and shape plays a prominent role in cell-cell and cell-substrate interaction. Also, the organization of these asperities is directly related to cellular cytoskeletal elements. In the present report, we describe a simple and objective method of studying electron micrographs to quantify the roughness of cell contours. Constant-length segments of cell boundaries are compared to reference circular segments with common extremities and enclosing the same area. This procedure was performed with a digitizer connected to a microcomputer, and it was used to analyse model contours or electron micrographs of (i) target tumour cells bound by cytotoxic T lymphocytes and (ii) thymocytes sticking to concanavalin A-coated surfaces. It is shown that this method allows precise quantification of cell deformation in adhesive zones, which may allow absolute evaluation of adhesive stimuli.

Animals↗

On-line laser-photometric monitoring of aerosol deposition in ventilated rabbit lungs.

A photometric technique was developed for on-line measurement of aerosol deposition in isolated, ventilated, and perfused rabbit lungs. A jet nebulizer was used for aerosolization of saline (hygroscopic particles) and di(2-ethylhexyl) sebacate (nonhygroscopic particles). Aerosol concentration (laser photometer, constructed for measurements in rabbit lungs) and flow rate (commercial pneumotachograph) were continuously monitored at the inlet of the tracheal cannula. Computer-assisted data processing allowed the breath-by-breath calculation of inhaled and exhaled aerosol mass, thus providing the deposition fraction. With the use of hygroscopic particles, however, this approach was hampered by the humidity-induced particle growth in the airways, leading to an overestimation of the aerosol concentration in exhaled air. This effect was corrected by an algorithm using a "particle growth factor" derived breath by breath from the photometer signal. To test the reliability of this approach, saline particles carrying technetium-99m label were aerosolized into rabbit lungs with the use of various ventilator settings, and the aerosol deposition was assessed in parallel by photometry and by radioactivity detection over the lung and over a trap in the exhaled-air circuit. Superimposable curves of cumulative aerosol deposition, with changes in kinetics dependent on the ventilator mode, were obtained. For a given ventilator setting, absolute values of the deposition fraction were 0.32 +/- 0.04 (radiotracer quantification) and 0.36 +/- 0.04 (photometry; means +/- SD; n = 4). We conclude that the presented laser-photometric technique allows reliable on-line monitoring of the deposition of both nonhygroscopic and hygroscopic aerosol particles in ventilated lungs.

Aerosols↗

Quantitative real-time RT-PCR using hybridization probes and imported standard curves for cytokine gene expression analysis.

Quantitative real-time or kinetic RT-PCR is increasingly used for the quantification of specific mRNA targets, especially in clinical applications. To quantify the mRNA of cytokines and their receptors, which play important roles in the pathogenesis of autoimmune diseases such as multiple sclerosis, we have developed quantitative two-step RT-PCR assays for IL-4, IL-4R, IFN-gamma, IFN-beta, and the housekeeping gene porphobilinogen deaminase (PBGD). The LightCycler system was used to quantify the copy numbers with the sequence-specific hybridization probe detection format. The quantification was carried out on the basis of standard curves generated with external homologous plasmids for each different parameter in relation to the gene expression of PBGD. Therefore, this procedure represents a relative quantification method with external standards, as the standard curves were used to obtain an absolute value for the copy numbers of the targets and the reference (PBGD). The new software version 3.5 of the LightCycler system allows the construction of a single parameter-dependent plasmid standard curve for the quantification of unknown samples from different runs. Here we demonstrate how to achieve precise and reproducible quantification, even when using measurements from different PCR runs.

Computer Systems↗

Validation of a simple bioanalytical method for the determination of DRF-6196, a novel oxazolidinone, in mouse plasma: application to a single-dose pharmacokinetic study.

An isocratic simple, specific, sensitive and reproducible high performance liquid chromatography (HPLC) method was developed and validated for the estimation of DRF-6196, a novel oxazolidinone in mouse plasma. This method involves a simple liquid/liquid extraction of DRF-6196 and the internal standard (IS; chlorzoxazone, CAS 95-25-0) from plasma into dichloromethane/ethyl acetate mixture that was evaporated under nitrogen. The HPLC analysis was carried out on an Inertsil ODS 2 column using 0.01 mol/L potassium dihydorgen ortho phosphate (pH 3.2) and acetonitrile (65:35, v/v) as mobile phase. The eluate was monitored using an UV detector set at 266 nm. Ratio of peak area of analyte to IS was used for quantification of plasma samples. The retention time of DRF-6196 and IS were 8.2 and 11.1 min, respectively. The assay was linear (r2 > 0.999) in the concentration range 0.1-50 microg/ml. Absolute recovery for analyte and IS was > 94 % from mouse plasma. The lower limit of quantification (LLOQ) of DRF-6196 was 0.1 microg/ml. The inter- and intra-day precision in the measurement of quality control (QC) samples, 0.1, 0.3, 15.0 and 40.0 microg/ml, were in the range 3.64 to 9.51 % relative standard deviation (RSD) and 0.92 to 6.23 % RSD, respectively. Accuracy in the measurement of QC samples was in the range 88.15 to 106.05 % of the nominal values. The analyte and IS were stable in the stability studies viz., benchtop, autosampler and freeze/thaw cycles. The stability of DRF-6196 was established for 1 month at -80 degrees C. The assay method was successfully applied to a pharmacokinetic study of DRF-6196 in mice.

Acetamides↗

Efficacy of doublecortin as a marker to analyse the absolute number and dendritic growth of newly generated neurons in the adult dentate gyrus.

Doublecortin (DCX), a microtubule-associated phosphoprotein, has been recently utilized as a marker of newly born neurons in the adult dentate gyrus (DG). Nonetheless, it is unknown whether DCX exclusively labels newly formed neurons, as certain granule cells with the phenotype of differentiated neurons express DCX. We addressed the authenticity of DCX as a marker of new neurons in the adult DG by quantifying cells that are positive for 5'-bromodeoxyuridine (BrdU), DCX and both BrdU and DCX in hippocampal tissues of adult rats treated with daily injections of BrdU for 12 consecutive days. We provide new evidence that neurons visualized with DCX immunostaining in the adult rat DG are new neurons that are predominantly born during the 12 days before euthanasia. This is confirmed by the robust expression of BrdU in 90% of DCX-positive neurons in the DG of animals injected with BrdU for 12 days. Furthermore, DCX expression is specific to newly generated healthy neurons, as virtually all DCX-positive cells express early neuronal antigens but lack antigens specific to glia, undifferentiated cells or apoptotic cells. As DCX expression is also robust in the dendrites, DCX immunocytochemistry of thicker sections facilitates quantification of the dendritic growth in newly born neurons. Thus, both absolute number and dendritic growth of new neurons that are generated in the adult DG over a 12-day period can be quantified reliably with DCX immunostaining. This could be particularly useful for analysing changes in dentate neurogenesis in human hippocampal tissues as a function of ageing or neurodegenerative diseases.

Animals↗

Vectorcardiographic quantification of infarct size in baboons.

A vectorcardiographic method has been developed for determining the absolute size of myocardial infarcts in baboons resulting from coronary artery ligation. Spatial area (mvolt . msec) and voltage (mvolt) difference-vectors were obtained for 8 animals by measuring the voltage loss and temporal deviation from pre- to post-ligation McFee scalar leads. The difference vectors were then correlated with the absolute infarct volumes, which were derived by histological assessment 10 days after ligation. Absolute lesion sizes ranged from approximately 2 cc to 14 cc, involving 10-30% of ventricular muscle mass. The correlation coefficient, r, for the area deviation index was 0.98 (SEE = +/- 0.24 cc); and for the voltage deviation index, r was 0.92 (SEE = +/- 0.51 cc). These results demonstrate that the severity of infarction can be accurately determined if prepathological vectorcardiograms are available.

Animals↗

Comparison of single- and dual-platform approaches to enumerate CD34(+) cells in bone marrow and mobilized peripheral blood stem cells.

BACKGROUND: Different flow cytometric methods have been developed to derive absolute CD34(+) cells in predicting transplant outcome. Two techniques for preparing cells for quantification of CD34(+) cells were compared. METHODS: Enumeration of CD34(+) cells in 16 samples of bone marrow (BM) and in 29 samples of mobilized peripheral blood stem cells (PBSC) obtained by leukapheresis was assessed simultaneously by single-platform (ProCOUNT kit) and dual-platform (Milan protocol) approaches within the first 3 h of collection. RESULTS: Absolute number of CD34(+) cells obtained in PBSC and BM using single- and dual-platform methods showed high determination coefficients as follows: for PBSC, slope = 1.0515 +/- 0.048, y-intercept = 88.638 +/- 52.45, and r(2) = 0.941, and for BM, slope = 1.0203 +/- 0.093, y-intercept = 122.25 +/- 20.65, and r(2) = 0.878. There were no statistically significant differences in absolute number of CD34(+) cells from PBSC between single-platform (mean 575/microL, range 70-3683/microL) and dual-platform (786/microL, range 51-3804/microL) assays. In contrast, absolute number of CD34(+) cells from BM was significantly lower (p = 0.0002) when enumerated by ProCount kit (135/microL, 14-758/microL) than with dual-platform method (260/microL, 74-889/microL). CONCLUSIONS: Both approaches can be used indistinctly to estimate absolute number of CD34(+) cells in PBSC but not in BM.

Antigens, CD34↗

A micromethod for the quantification of atenolol in plasma using high-performance liquid chromatography with fluorescence detection: therapeutic drug monitoring of two patients with severe coronary insufficiency before cardiac surgery.

A simple, rapid, selective, and sensitive analytical method was developed for the quantification of atenolol in small volumes of plasma, by high-performance liquid chromatography with fluorescence detection. Only 200 microL of plasma was used for chromatographic analysis. Separation was performed on a C18 reverse-phase column (4 microm) using a binary mobile phase consisting of 0.05 M of phosphate buffer, pH 5.5, and methanol (80:20, vol/vol) at a flow rate of 0.7 mL/minute. The retention times of atenolol and of the internal standard (sotalol) were 12.7 and 10.4 minutes, respectively. Validation of this analytical method showed a good linear correlation (8-2000 ng/mL), high sensitivity (quantification limit: 8 ng/ml and detection limit: 4 ng/mL), accuracy of 99.3%, and intraday and interday precision of 5.3% and 6.9%, respectively. Absolute recovery was 93.7%. The method was found to be robust, with acceptable stability. The analytical method was validated by the quantification of atenolol in plasma obtained from 2 patients with unstable angina, scheduled for myocardium revascularization surgery, who were chronically treated with 50 mg of atenolol administered per os once a day. The method developed was found to be adequate for use in pharmacokinetic studies and in adjusted dose pharmacotherapy.

Administration, Oral↗

Quantitative determination of ragaglitazar in rat plasma by HPLC: validation and application in pharmacokinetic study.

A specific, accurate, precise and reproducible high-performance liquid chromatography (HPLC) method was developed for the estimation of ragaglitazar [(-) DRF 2725, NNC 61-0029], a novel anti-diabetic agent, in rat plasma. The assay procedure involved simple liquid/liquid extraction of ragaglitazar and internal standard (IS, troglitazone) from plasma into ethyl acetate. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40 degrees C. The residue was reconstituted in the mobile phase and injected onto a Kromasil KR 100 - 5C(18) column (4.6 x 250 mm, 5 micro m). Mobile phase consisting of 0.01 M potassium dihydorgen ortho phosphate (pH 3.2) and acetonitrile (30:70, v/v) was used at a flow rate of 1.0 mL/min. The eluate was monitored using an UV detector set at 240 nm. Ratio of peak area of analyte to IS was used for quantification of plasma samples. Nominal retention times of IS and ragaglitazar were 6.9 and 12.2 min, respectively. The standard curve for ragaglitazar was linear (r(2) > 0.999) in the concentration range 0.2-100 micro g/mL. Absolute recovery was >87% from rat plasma for both analyte and IS. The lower limit of quantification (LLOQ) of ragaglitazar was 0.2 micro g/mL. The inter- and intra-day precision in the measurement of quality control (QC) samples, 0.2, 1.0, 5.0 and 50 micro g/mL, were in the range 1.32-3.70% relative standard deviation (RSD) and 1.19-9.39% RSD, respectively. Accuracy in the measurement of QC samples was in the range 94.28-107.45%. Analyte and IS were stable in the battery of stability studies, viz. benchtop, autosampler and freeze/thaw cycles. Stability of ragaglitazar was established for 1 month at -20 degrees C. The application of the assay to a pharmacokinetic study in rats is described.

Animals↗

Second primary oral and pharyngeal cancers in subjects diagnosed with oral and pharyngeal cancer.

Patients diagnosed with oral and pharyngeal (OP) cancer have a substantial excess risk of second OP cancer, but risk quantification is still uncertain and scanty information is available on the absolute excess risk of second OP cancer. We considered the risk of second OP primary cancer in a population-based series of 3,092 first primary OP cancers registered between 1974 and 2003 in the Swiss Cantons of Vaud and Neuchâtel (total population of about 786,000 inhabitants). A total of 233 second OP cancers were registered, versus 7.4 expected, corresponding to a SIR of 31.7 (95% confidence interval (CI) 27.7-36.0). The SIR was 68.5 in the first year after diagnosis of the first primary, and declined thereafter, leveling around 20. The SIR was 30.7 when the site of first neoplasm was the oral cavity, 42.5 for the tongue and 28.1 for the oropharynx or hypo-pharynx. Corresponding values for topographies of second primaries were 28.8, 50.4 and 26.2. The cumulative risk of second OP cancer 15 years after diagnosis of first OP cancer approached 22% in men and 17% in women. The incidence of first primaries increased over 20-fold between age 30-39 and 70-79, whereas there was no rise with age for second neoplasms.

Aged↗

Effects of cadmium on metallothionein-I and metallothionein-II mRNA expression in rat ventral, lateral, and dorsal prostatic lobes: quantification by competitive RT-PCR.

Highly sensitive, sequence-specific competitive reverse transcriptase-polymerase chain reaction (RT-PCR) protocols were established for the detection and quantification of metallothionein (MT)-I and MT-II messages, in absolute values, in rat tissues. Detection limits for these protocols were in the range of 5 to 10 amol per microgram total RNA. Levels of MT-I and MT-II transcripts in the three major prostatic lobes, kidney, and testis were measured in untreated and cadmium (Cd)-treated rats. The dorsal prostate (DP), lateral prostate (LP), kidney, and testis expressed substantial levels of MT-I and MT-II mRNA while the ventral prostate (VP) had extremely low levels of the transcripts. Cd treatment induced higher levels of MT-I and/or MT-II mRNA expression in all tissues studied with the exception of LP. In the LP, Cd treatment caused reductions of MT-I and MT-II mRNA levels. The Cd-induced levels attained in the VP following Cd exposure were still markedly lower than those found in the kidney, testis, LP, and DP of untreated animals. These findings contradict previous claims that the MT genes in rat VP are unresponsive to Cd activation. The susceptibility of VP to Cd toxicity/carcinogenicity may therefore be explained by low levels of Cd-induced expression rather than lack of induction of MTs.

Animals↗