Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “quantitative analysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed2001

Quantitative analysis of Epstein-Barr virus DNA in plasma and serum: applications to tumor detection and monitoring.

The recent interest in cell-free tumor-derived DNA in the plasma and serum of cancer patients has opened up numerous diagnostic possibilities. One type of tumor-derived DNA that has been detected in plasma/serum is viral DNA. One example of circulating viral nucleic acid is Epstein-Barr virus (EBV) DNA, which has been found in the plasma and serum of patients with nasopharyngeal carcinoma (NPC), certain lymphomas, and gastric carcinoma. Quantitative analysis of circulating EBV DNA in NPC has demonstrated a positive correlation with disease stage and a strong relationship with clinical events, as well as being of prognostic importance. For EBV-associated lymphomas, quantitative EBV DNA analysis has also been found to correlate closely with clinical progress. It is expected that plasma/serum EBV DNA analysis will soon be incorporated into the routine investigative protocol of EBV-associated malignancies.

Biomarkers, Tumor↗
PubMed1984

Quantitative analysis of alpha, beta-thujone, pulegone, safrole, coumarin and beta-asarone in alcoholic beverages by selected-ion monitoring.

Interest in the quantitative analysis of flavouring agents in alcoholic beverages arises from the possible toxicological consequences deriving from their use. The method reported here, based on gas chromatography with selected-ion monitoring mass spectrometry (SIM), allows the simultaneous measurement of alpha, beta-thujone, pulegone, safrole, coumarin and beta-asarone at the ppb level in alcoholic beverages.

Alcoholic Beverages↗
PubMed2006

Comparison of two solid-phase microextraction methods for the quantitative analysis of VOCs in indoor air.

Competitive adsorption on adsorptive solid-phase microextraction (SPME) fibres implies careful determination of operating conditions for reliable quantitative analysis of VOCs in indoor air. With this objective, two analytical approaches, involving non-equilibrium and equilibrium extraction, were compared. The average detection limit obtained for GC-MS analysis of nine VOCs by the equilibrium method is 0.2 microg m(-3), compared with 1.9 microg m(-3) with the non-equilibrium method. The effect of the relative humidity of the air on the calibration plots was studied, and shown to affect acetone adsorption only. Hence, the concentrations that can be accurately determined are up to 9 micromol m(-3). The methods were then applied to indoor air containing different concentrations of VOCs. The non-equilibrium method, involving short extraction time, can be used for detection of pollution peaks whereas equilibrium extraction is preferable for measurement of sub-microg m(-3) ground concentration levels.

Adsorption↗
PubMed1986

Quantitative analysis of rubral degeneration following neonatal deafferentation.

The effect of neonatal hemicerebellectomy on the cytoarchitecture of the red nucleus was investigated in the rat. Quantitative analysis revealed a 31% loss of neurons in the magnocellular red nucleus contralateral to the lesion. This cell loss was accompanied by a similar decrease in the cross-sectional area of the red nucleus. To provide insight into this degenerative process, the neonatal status of the normal cerebellorubral projection was determined using anterograde transport of HRP-WGA which was injected into the deep cerebellar nuclei at various times during the first 10 postnatal days. A definitive cerebellorubral projection was not detectable before postnatal day 8. The data indicate that the rubral afferent fibers from the cerebellum were removed before they reached their target. These results are significant in light of the aberrant projections that develop after neonatal lesions.

Afferent Pathways↗
PubMed1984

Automated quantitative analysis of coordinated locomotor behaviour in rats.

Disturbances of motor coordination are usually difficult to quantify. Therefore, a method was developed for the automated quantitative analysis of the movements of the dyed paws of stepping rats, registered by a colour TV camera. The signals from the TV-video system were converted by an electronic interface into voltages proportional to the X- and Y-coordinates of the paws, from which a desktop computer calculated the movements of these paws in time and distance. Application 1 analysed the steps of a rat walking in a hollow rotating wheel. The results showed low variability of the walking pattern, the method was insensitive to low doses of alcohol, but was suitable to quantify overt, e.g. neurotoxic, locomotor disturbances or recovery thereof. In application 2 hurdles were placed in a similar hollow wheel and the rats were trained to step from the top of one hurdle to another. Physostigmine-induced disturbances of this acquired complex motor task could be detected at doses far below those that cause overt symptoms.

Animals↗
PubMed2004

Quantitative analysis of adenosine A1 receptors in human brain using positron emission tomography and [1-methyl-11C]8-dicyclopropylmethyl-1-methyl-3-propylxanthine.

Fully quantitative analysis of the adenosine A(1) receptor (A1R) in the brain with (11)C-MPDX and positron emission tomography is reported. The kinetics is described using a two-tissue three-compartment model, and estimated binding potentials correspond well with the estimates made by Logan plot. The image of the binding potential of the MPDX is physiologically reasonable. We conclude that MPDX is applicable to the visualization of the A1Rs in the brain with Logan plot.

Adult↗
PubMed2000

Comprehensive two-dimensional gas chromatography and chemometrics for the high-speed quantitative analysis of aromatic isomers in a jet fuel using the standard addition method and an objective retention time alignment algorithm

A high-speed quantitative analysis of aromatic isomers in a jet fuel sample is performed using comprehensive two-dimensional gas chromatography (GC x GC) and chemometrics. A GC x GC separation time of 2.8 min is achieved for three aromatic isomers in jet fuel, which is 5 times faster than a reference method in which a singlecolumn separation resolves two of the three isomers of interest. The high-speed GC x GC separation is more than 10 times faster than a recent GC x GC separation that fully resolves the three components of interest in gasoline. The high-speed GC x GC analysis of jet fuel is accomplished through short GC columns, high gas velocities, and partial chromatographic peak resolution followed by chemometric resolution of overlapped peaks. The standard addition method and an objective retention time alignment algorithm are used to correct for retention time variations prior to the chemometric data analysis. The standard addition method corrects for chemical matrix effects that cause analytes in complex samples to have peak shapes, widths, and retention times that differ considerably from those of calibration standards in pure solvents. The retention time alignment algorithm corrects for the relatively small retention time variations caused by fluctuating instrumental parameters such as flow rate and temperature. The use of data point interpolation in the retention time alignment algorithm results in a more accurate retention time correction then previously achieved. The generalized rank annihilation method (GRAM) is the chemometric technique used to resolve the overlapped GC x GC peaks. The correction of retention time variations allows for successful GRAM signal deconvolution. Using the retention time alignment algorithm, GRAM quantification accuracy and precision are improved by a factor of 4. The methodology used in this paper should be applicable to other comprehensive separation methods, such as two-dimensional liquid chromatography, liquid chromatography coupled with capillary electrophoresis, and liquid chromatography coupled with gas chromatography.

Journal Article↗
PubMedDate not supplied

Endoscopic laser flowmetry: a valid method for detection and quantitative analysis of inhalation injury.

Hyperemia of the tracheobronchial area is a major sign of inhalation injury. However, this is usually a qualitative symptom, without quantitative measurement. We have developed a technique to diagnose inhalation injury and to analyze damaged areas quantitatively with laser-doppler flowmetry. In chronically instrumented sheep (N = 10), the tissue blood flow in the wall of second generation bronchi was determined with an endoscopic flowmeter probe. After baseline data had been obtained, the right lung was exposed to smoke in seven animals. Three sham-smoked animals underwent the same procedure, but without actual smoke. The bronchial blood flow was measured again 30 minutes after insufflation in both groups. Inhalation injury caused a significant increase in flow, from 35.1 +/- 2.6 to 51.7 +/- 2.1 ml/min.100 gm tissue in the airway of the smoked lungs but not in the control lungs. This increase correlated with an increase in the carboxyhemoglobin level (r = 0.87). The sham-smoked animals showed no change in bronchial blood flow. A valid technique for diagnosing inhalation injury in the early phase and a quantitative analysis of injured areas has been demonstrated.

Animals↗
PubMed1982

Quantitative analysis of intramembrane particle (IMP) distribution on biomembranes after freeze-fracture preparation by a computer-based technique.

An improved method for the quantitative analysis of intramembrane particles (IMPs) on freeze-fracture faces of biomembranes is described. The analysis provides, first, the number of IMPs per 1 micrometer2, second, the coefficient of dispersion (CD) of unweighted and weighted (i.e. the finite size is taken into consideration) IMP distribution, and, third, the diameters of IMPs. Additional data for further statistical evaluation are also derived. These data make it possible to numerically describe and characterize fracture faces of a membrane in a defined physiological state. They allow for comparison of normal membranes with experimentally induced alterations of the same specimen in other experiments, and for observation of differences between normal and malignant cells. Furthermore, such an analysis provides the basis for a dynamic interpretation of biomembrane components seen on the static freeze-fracture micrographs. With this numerical analysis, descriptive terms for IMP distribution such as 'random', 'aggregated' or 'clustered', which cannot be evaluated or verified, are avoided. The method, based on the Poisson statistic which provides a means for the description of different particle density distributions, is described. The validity of the method is demonstrated on artificially generated pictures and by an analysis of erythrocyte membranes before and after spectrin depletion.

Computers↗
PubMed1985

Quantitative analysis of AIDS-related virus-carrying cells by plaque-forming assay using an HTLV-I-positive MT-4 cell line.

Quantitation of acquired immune deficiency syndrome (AIDS)-related virus-bearing cells was analyzed by a newly developed plaque-forming assay. A chemically adherent HTLV-I-positive MT-4 cell monolayer was used as the cytolytic responder cells to the AIDS-virus infection. When AIDS-virus-infected cells (Molt-4/HTLV-III, H9/HTLV-III, and CEM/LAV) were seeded with MT-4 cells, plaques were observed corresponding to the number of HTLV-III-positive cells plated. Plaque formation was inhibited by the addition of anti-HTLV-III-positive serum (neutralizing antibody) to the agarose medium. These data suggest that this plaque-forming assay technique should be useful for the quantitative analysis of AIDS-virus-bearing cells.

Acquired Immunodeficiency Syndrome↗
PubMed1978

[Quantitative analysis of the electromyogram using triggered correlation].

A study has been made to determine the usefulness of triggered correlation as a method of automatic quantitative analysis of graphic representations of the somatic electric currents associated with muscular action. Although an electromyogram is neither a normally distributed nor a stationary random process, the method has been found to be suitable for clinical electromyography. The method is easy to use, with measuring values that may be used for diagnostic purposes being obtained within a few seconds. In the case of normal subjects and patients with neuromuscular diseases, parameters of triggered correlograms are compared with those of visuamanually analyzed or digitally averaged potentials of individual motor units.

Electromyography↗
PubMed1996

[A quantitative analysis of the cells infected with Epstein-Barr virus in the peripheral blood mononuclear cells derived from the patients with infectious mononucleosis].

The quantitative analysis of the cells infected with Epstein-Barr virus was performed on the peripheral blood mononuclear cells from the patients with infectious mononucleosis, by using in situ hybridization with Epstein-Barr virus encoded small nuclear RNA1 (EBER1). An alkaline-phosphatase conjugated oligonucleotide probe complementary to EBER1 was used as an antisense probe, while oligonucleotide DNA probe compatible with the sequence of EBER1 was used as a sense probe, control probe. The EBER1 positive cells on the slide-glass were enumerated microscopically. In situ hybridization revealed that 50,000 peripheral blood mononuclear cells from the patients in the acute phase of infectious mononucleosis contained 35 +/- 36 cells infected with Epstein-Barr virus (n = 11). The cells infected with Epstein-Barr virus apparently decreased in the convalescence of all the patients with infectious mononucleosis and the mean of the cells infected with Epstein-Barr virus was 3 +/- 4 in the convalescence (n = 6) (p < 0.02). On the other hand, no positive cells were detected in healthy individuals with past-infection of Epstein-Barr virus (n = 10) or without any previous Epstein-Barr virus infection (n = 11). The striking increase of the cells with Epstein-Barr virus genome was clearly demonstrated in the peripheral blood mononuclear cells from the patients with infectious mononucleosis.

Child↗
PubMed2006

An accurate quantitative analysis of polymorphs based on artificial neural networks.

Measurement precision based on homogeneous and accurate standard samples has been reported to result in significant improvement in the sensitivity and accuracy of the quantitative analysis of polymorphic mixtures. The purpose of this study was to further improve the accuracy of the quantitation based on data processing by artificial neural networks (ANNs), using such high quality standard samples. Homogeneous powder mixtures of alpha- and gamma-forms of indomethacin (IMC) at various ratios (0-50% alpha-form content) were subjected to X-ray powder diffractometry. The two diffraction peaks selected as the best combination in multiple linear regression (MLR) were used in the ANN with an extended Kalman filter as a training algorithm. The results obtained by ANN had better predictive accuracy at lower contents (0-5%) compared to those of MLR. ANNs for the diffraction data based on high quality standard samples provide an extremely precise and accurate quantification for polymorphic mixtures.

Algorithms↗
PubMed2007

A method for quantitative analysis of spatially variable physiological processes across leaf surfaces.

Many physiological processes are spatially variable across leaf surfaces. While maps of photosynthesis, stomatal conductance, gene expression, water transport, and the production of reactive oxygen species (ROS) for individual leaves are readily obtained, analytical methods for quantifying spatial heterogeneity and combining information gathered from the same leaf but with different instruments are not widely used. We present a novel application of tools from the field of geographical imaging to the multivariate analysis of physiological images. Procedures for registration and resampling, cluster analysis, and classification provide a general framework for the analysis of spatially resolved physiological data. Two experiments were conducted to illustrate the utility of this approach. Quantitative analysis of images of chlorophyll fluorescence and the production of ROS following simultaneous exposure of soybean leaves to atmospheric O3 and soybean mosaic virus revealed that areas of the leaf where the operating quantum efficiency of PSII was depressed also experienced an accumulation of ROS. This correlation suggests a causal relationship between oxidative stress and inhibition of photosynthesis. Overlaying maps of leaf surface temperature and chlorophyll fluorescence following a photoinhibition treatment indicated that areas with low operating quantum efficiency of PSII also experienced reduced stomatal conductance (high temperature). While each of these experiments explored the covariance of two processes by overlaying independent images gathered with different instruments, the same procedures can be used to analyze the covariance of information from multiple images. The application of tools from geographic image analysis to physiological processes occurring over small spatial scales will help reveal the mechanisms generating spatial variation across leaves.

Algorithms↗
PubMed1999

Quantitative Analysis of Tissue Doppler Data.

A visual qualitative analysis of color Doppler myocardial images cannot show the low velocity changes in myocardial walls, and a quantitative analysis of tissue Doppler data is mandatory for an analysis of color Doppler myocardial recordings, including an assessment of myocardial velocity gradient across the thickness of the wall. Measurement of myocardial velocity in each pixel should provide access to a broader pathophysiological insight into regional contraction across wall thickness and into all myocardial segments throughout the cardiac cycle.

Journal Article↗
PubMed2006

Quantitative analysis of semi-supine exercise echocardiography--influence of age on myocardial Doppler imaging indices.

OBJECTIVES: This study was performed to evaluate the feasibility of quantitative analysis of exercise echocardiography using pulsed wave Doppler myocardial imaging (DMI) and to examine the relation between age and DMI parameters at rest and during graded exercise in normal subjects. METHODS AND RESULTS: Seventy-two healthy volunteers were divided into three age groups (group I, age < or = 40 years, group II, age 41 - 59 years and group III, age > or = 60 years), and underwent a semi-supine exercise echocardiogram. Peak systolic velocity (SV), time to peak SV (TPV), systolic velocity time integral (VTI) and peak diastolic velocities (VE and VA) were measured off-line. There was a heterogeneity in DMI parameters between different myocardial walls and a gradient was found between basal and mid segments. Both persisted during exercise. Group I had significantly higher TPV than groups II and III. Increase in workload was accompanied by an increase in velocities, while TPV decreased. Differences between groups persisted throughout exercise. CONCLUSIONS: Off-line measurements of DMI parameters are feasible during exercise. SV and E decline as age increases while A increases. SV already increases at low charge exercise and may serve as a quantitative marker for the detection of myocardial viability. Change of the absolute DMI velocity values during exercise may provide a better indicator of ischaemia or viability than the absolute values themselves.

Adult↗
PubMed2003

Quantitative analysis of Escherichia coli metabolic phenotypes within the context of phenotypic phase planes.

In silico models of Escherichia coli metabolism have been developed to predict metabolic behavior and propose experimentally testable hypotheses. However, a thorough assessment of the metabolic phenotype requires well-designed experimentation and reproducible experimental techniques. A method for the quantitative analysis of E. coli metabolism in vivo within the framework of in silico phenotypic phase plane analysis is presented. Using this approach, we have quantitatively studied E. coli metabolism in various environmental conditions and nutritional media. Our experimental methodology, in combination with steady-state metabolic models, can be used to study biological properties and evaluate the metabolic capabilities of microbes.

Aerobiosis↗
PubMed1990

Titration of human immunodeficiency virus type 1 (HIV-1) and quantitative analysis of virus expression in vitro using liquid RNA-RNA hybridization.

An assay is described for titration of human immunodeficiency virus type 1 (HIV-1) and for quantitative analysis of virus expression in vitro. The assay utilizes a liquid RNA-RNA hybridization method coupled with reversible target capture (RTC) on oligo(dT) derivatized magnetic particles. The assay provides a rapid, specific, and sensitive method for quantitation of HIV-1 RNA molecules present either in cells or in viral particles from cell-free culture media. Chronically infected monocytoid U1.1 cells were found to carry 52 pg HIV-1 RNA per 200,000 cells (160 HIV-1 RNA molecules per cell). In contrast, acutely infected CEM and H9 cells carried 3010 and 4370 pg HIV-1 RNA per 200,000 cells (9040 and 13,110 HIV-1 RNA molecules per cell, respectively). No hybridization was observed with uninfected cells or cells infected with HIV-2, HTLV-I, HTLV-II, or EBV. Use of liquid HIV-1 RNA hybridization in association with HIV-1 protein detection methods permits more complete characterization of HIV-1 expression in host cells than either method alone, and also provides a method for standardizing preparations of virus.

Acquired Immunodeficiency Syndrome↗