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 667 records · Page 37Linked to original sources
PubMed1996

Effects of formic acid hydrolysis on the quantitative analysis of radiation-induced DNA base damage products assayed by gas chromatography/mass spectrometry.

Gas chromatography/mass spectrometry (GC/MS-SIM) is an excellent technique for performing both qualitative and quantitative analysis of DNA base damage products that are formed by exposure to ionizing radiation or by the interaction of intracellular DNA with activated oxygen species. This technique commonly uses a hot formic acid hydrolysis step to degrade the DNA to individual free bases. However, due to the harsh nature of this degradation procedure, the quantitation of DNA base damage products may be adversely affected. Consequently, we examined the effects of various formic acid hydrolysis procedures on the quantitation of a number of DNA base damage products and identified several factors that can influence this quantitation. These factors included (1) the inherent acid stabilities of both the lesions and the internal standards; (2) the hydrolysis temperature; (3) the source and grade of the formic acid; and (4) the sample mass during hydrolysis. Our data also suggested that the N,O-bis (trimethylsilyl)trifluoroacetamide (BSTFA) derivatization efficiency can be adversely affected, presumably by trace contaminants either in the formic acid or from the acid activated surface of the glass derivatization vials. Where adverse effects were noted, modifications were explored in an attempt to improve the quantitation of these DNA lesions. Although experimental steps could be taken to minimize the influence of these factors on the quantitation of some base damage products, no single procedure solved the quantitation problem for all base lesions. However, a significant improvement in the quantitation was achieved if the relative molecular response factor (RMRF) values for these lesions were generated with authentic DNA base damage products that had been treated exactly like the experimental samples.

DNA Damage↗
PubMedDate not supplied

The Korean American woman's face: anthropometric measurements and quantitative analysis of facial aesthetics.

OBJECTIVES: To assess the differences in facial proportions between Korean American (KA) women and North American white (NAW) women and to quantitatively describe aesthetic facial features in the KA women. DESIGN: Anthropometric survey and facial aesthetic evaluation. PARTICIPANTS: Volunteer sample of KA women (n = 72) who served as models for part 1 of the study and a different sample of KA women (n = 5) and men (n = 5) who served as judges for part 2 of the study. All subjects were between ages 18 and 35 years and had Korean parents and no previous facial surgery or trauma. Intervention For part 1 of the study, standardized and referenced frontal and lateral photographs were taken of the models, and 26 standard anthropometric measurements were determined. Results were compared with published NAW standards. For part 2 of the study, 10 judges evaluated frontal views of the models for facial aesthetics using a visual analog scale. Quantitative analysis was done of the faces of attractive KA women (>90th percentile in aesthetic scores) and comparisons were made with the faces of NAW women and average KA women. RESULTS: The KA woman's face did not fit the neoclassical facial canons. Compared with NAW women, 24 of the 26 facial measurements in KA women were significantly different. Only 9 of the 26 facial measurements were significantly different when the attractive KA women were compared with the NAW women. Nine of the 17 nonsignificant facial measurements were very similar to those of the NAW women; many of these facial features centered around the midface. CONCLUSIONS: Although the average KA woman's facial anthropometric measurements were very different from those of the NAW woman, attractive KA women reflected many of the facial features of NAW women. These findings support the need for ethnically sensitive facial canons and further research into transcultural aesthetics.

Adolescent↗
PubMed1989

Poly(ethylene glycol)-induced shrinkage of Sephadex gel. A model system for quantitative analysis of osmoelastic coupling.

Shrinkage of Sephadex gels caused by addition of a high-molecular weight molecule, poly(ethylene glycol) (PEG) was studied. A quantitative analysis based on the cross-linked network theory by Flory and Tanaka (Tanaka, T. 1978. Phys. Rev. Lett. 40:820-823) showed that the shrinkage is due to a mechanochemical coupling between the elasticity of the network and the osmotic stress arising from preferential exclusion of PEG. These results may provide good evidence for "osmoelastic coupling", the coupling between elasticity of macromolecular structures and osmotic stress, which has been predicted in some biological systems such as phospholipid bilayer membranes (Ito, T., M. Yamazaki, and S. Ohnishi. 1989. Biochemistry. 28:5626-5630; Yamazaki, M., S. Ohnishi, and T. Ito. 1989. Biochemistry. 28:3710-3715) or actin filaments.

Biopolymers↗
PubMed1985

Isolation and quantitative analysis of phosphatidylglycerol and glycolipid molecular species using reversed-phase high-performance liquid chromatography with flame ionization detection.

Conditions are described for the quantitative analysis of phosphatidylglycerol and plant glycolipid molecular species by reversed-phase high-performance liquid chromatography employing a commercially available flame ionization detector. Direct detection on a mass basis overcomes the problem of poor detectability found with most natural lipids. Effective mobile phases composed primarily of volatile solvents are described. Splitting of the column eluate stream allows a portion of each individual molecular species to be recovered for other types of analysis.

Chromatography, Gas↗
PubMed2004

[A software program for quantitative analysis of alveolar oxygen partial pressure (p(A)O(2)) with oxygen-sensitive (3)He-MRI].

PURPOSE: To develop a software tool for quantitative analysis of alveolar oxygen partial pressure (p(A)O(2)) as well as its time course during apnea. MATERIAL AND METHODS: T (1)-relaxation times of hyperpolarized (3)He are reduced by paramagnetic oxygen rendering (3)He-MRI sensitive to oxygen and thus allowing the assessment of the local oxygen partial pressure in the pulmonary airspaces. Oxygen-related relaxation and loss of polarization by RF-excitation can be discriminated by acquiring two image series with varying interscan delay and/or flip angles. Software was developed to calculate the p(A)O(2) and the decay rate in user-defined regions of interest (ROIs) automatically. Moreover, parameter maps can be calculated. In addition to the analysis of 2-dimensional data sets, the software allows the evaluation of 3-dimensional measurements for the first time. Artifacts due to lung motion were reduced by implementing a motion correction algorithm. RESULTS: The software was successfully applied to data sets from healthy volunteers and from patients with various lung diseases. The parameter maps demonstrated a more homogeneous distribution of p(A)O(2) for the volunteers than for the patients. A regional increase in p(A)O(2) was found in a few patients. CONCLUSION: The described software allows the absolute quantification of p(A)O(2) as well as its variation over time. In the future, therefore, the software may gain importance for detecting mismatches between ventilation and perfusion, e. g., in patients with pulmonary embolism or chronic obstructive lung diseases.

Adult↗
PubMed2006

GREM, a technique for genome-wide isolation and quantitative analysis of promoter active repeats.

We developed a technique called GREM (Genomic Repeat Expression Monitor) that can be applied to genome-wide isolation and quantitative analysis of any kind of transcriptionally active repetitive elements. Briefly, the technique includes three major stages: (i) generation of a transcriptome wide library of cDNA 5' terminal fragments, (ii) selective amplification of repeat-flanking genomic loci and (iii) hybridization of the cDNA library (i) to the amplicon (ii) with subsequent selective amplification and cloning of the cDNA-genome hybrids. The sequences obtained serve as 'tags' for promoter active repetitive elements. The advantage of GREM is an unambiguous mapping of individual promoter active repeats at a genome-wide level. We applied GREM for genome-wide experimental identification of human-specific endogenous retroviruses and their solitary long terminal repeats (LTRs) acting in vivo as promoters. Importantly, GREM tag frequencies linearly correlated with the corresponding LTR-driven transcript levels found using RT-PCR. The GREM technique enabled us to identify 54 new functional human promoters created by retroviral LTRs.

Endogenous Retroviruses↗
PubMed1983

Quantitative analysis of the high-frequency components of the terminal portion of the body surface QRS in normal subjects and in patients with ventricular tachycardia.

Quantitative analysis of the high-frequency components of the terminal portion of the surface QRS was performed in 42 normal subjects (group 1, ages 18-67 years, mean +/- SEM 34.7 +/- 2.2 years) and in 12 patients with symptomatic, sustained ventricular tachycardia (VT) (group 2, ages 48-76 years, mean 59 +/- 2.3 years). Signal averaging and high-pass, bidirectional digital filtering were used for analysis. The total duration of the QRS, the duration of the low-amplitude signals (less than 40 microV) in the terminal portion of the QRS and the amplitude of the signals in the last 40 and 50 msec of the QRS were measured at filter settings of 25 and 40 Hz. Reproducibility of the measurements was tested in 15 normal subjects by comparing results obtained from two consecutive recordings. Significant differences were found between normal subjects and VT patients for all four indexes at both 25- and 40-Hz filters. Specific values for each of the indexes were identified at the 40-Hz filtering, which could separate normal subjects from VT patients (20 microV for the amplitude of last 40 msec; 30 microV for the amplitude of last 50 msec; 120 msec for the total duration; and 39 msec for the low-amplitude signal of the filtered QRS). Using these values for the four indexes, respectively, 90%, 98%, 100% and 90% of the normal subjects and 83%, 83%, 58% and 83% for the VT group were correctly classified. The results show that the high-frequency analysis of the signal-averaged body surface QRS is a reliable, reproducible, noninvasive method for distinguishing patients with VT from normal subjects.

Adolescent↗
PubMed2002

Atherosclerotic plaque characterization by quantitative analysis using intravascular ultrasound: correlation with histological and immunohistochemical findings.

The aim of this study was to clarify whether atherosclerotic plaque morphology, as defined by quantitative analysis with intravascular ultrasound (IVUS) images, was related to the immunohistochemical findings. Twenty-five coronary lesions in 25 patients who had ultrasound guidance during directional coronary atherectomy (DCA) were enrolled. The lesions retrieved by DCA were analyzed and divided into 3 groups (lesions infiltrated with both macrophages and lymphocytes: group IML; lesions infiltrated with macrophages but not lymphocytes: group IM; and non-infiltrated lesions: group NI). The mean plaque echo level divided by the mean adventitia echo level (MPEL/MAEL) and the heterogeneity of the distribution of plaque echo levels (HDPEL) were calculated. The proportion of patients with acute coronary syndromes was significantly different among the groups: IML (n=14), IM (n=5), and NI (71%, 0% and 17%, respectively; p<0.01). The pre-DCA HDPEL value was highest in group IML and lowest in group NI; however, no significant differences in MPEL/MAEL values were found. The results suggest that plaque morphology, as defined by IVUS images, was related to the immunohistochemical findings. The increase in HDPEL correlated with the presence of immune inflammation.

Angina Pectoris↗
PubMed1998

[Application of simple OMA system for rapid spectrochemical quantitative analysis to steel sample composition].

In this paper, the experimental method and characteristic of a simple optical multichannel analyzer (OMA) system used for rapid spectrochemical quantitative analysis was introduced. Mangangese and chromium contents in different steel samples were measured. The reliability of experimental results was discussed according to the mathematical statistics theory. Analytical results were compared with those of chemical and ICP analysis.

English Abstract↗
PubMed2006

[Quantitative analysis of psychometric indicators among 20-40 years old Georgian men and women of normal physical development].

The aim of the work was to establish quantitative analysis of individual indicators and constitutional types among 20-40 years old Georgian men and women of normal physical development. The studied contingent was divided into 4 scales of age: 20-24 years old 65 women and 35 men; 25-29 years old 35 women and 25 men; 30-34 years old 10 women and 5 men; and 35-39 years old 10 women and 10 men. On the basis of the conducted research it was established that younger Georgian women of normal physical development are mainly sanguines, extroverts, express middle logic intellect, plastic-dynamic mood, constitutional and stable middle excitement, and are mainly harmonic and dynamic constitutional types. Younger Georgian men are sanguines, extroverts, express middle logic intellect plastic - dynamic and constitutional-stable mood, and are mainly harmonic and dynamic constitutional types.

Adult↗
PubMed2006

Quantitative analysis of acrylamide labeled serum proteins by LC-MS/MS.

Isotopic labeling of cysteine residues with acrylamide was previously utilized for relative quantitation of proteins by MALDI-TOF. Here, we explored and compared the application of deuterated and (13)C isotopes of acrylamide for quantitative proteomic analysis using LC-MS/MS and high-resolution FTICR mass spectrometry. The method was applied to human serum samples that were immunodepleted of abundant proteins. Our results show reliable quantitation of proteins across an abundance range that spans 5 orders of magnitude based on ion intensities and known protein concentration in plasma. The use of (13)C isotope of acrylamide had a slightly greater advantage relative to deuterated acrylamide, because of shifts in elution of deuterated acrylamide relative to its corresponding nondeuterated compound by reversed-phase chromatography. Overall, the use of acrylamide for differentially labeling intact proteins in complex mixtures, in combination with LC-MS/MS provides a robust method for quantitative analysis of complex proteomes.

Acrylamides↗
PubMed2006

Quantitative analysis of 11C-verapamil transfer at the human blood-brain barrier for evaluation of P-glycoprotein function.

UNLABELLED: P-glycoprotein in the blood-brain barrier (BBB) has been found to be associated with several types of neurologic damage. (11)C-Verapamil has been used for in vivo imaging of P-glycoprotein function in the BBB by PET, but metabolites in plasma complicate the quantitative analysis of human studies. In this study, we validated the quantification methods of (11)C-verapamil transfer from plasma to the brain in humans. METHODS: The transfer rate constant from plasma to the brain, K(1), was estimated by nonlinear least squares (NLS) with a 2-input compartment model, including the permeation of the main metabolite in plasma at the BBB, and with a 1-input compartment model using only 15-min data that contained little metabolite in plasma. K(1) was also estimated by graphical analysis of an integration plot that uses only early-time data, before the appearance of metabolites, and the estimated K(1) was compared with that obtained by the NLS method. In the simulation study, the reliability of parameter estimates in the graphical analysis method was investigated for various values of rate constants, time ranges of parameter estimations, and noise levels. RESULTS: (11)C-Verapamil in plasma gradually converted to its metabolites, and about 45% of the radioactivity in the plasma specimen was associated with (11)C-verapamil metabolites at 30 min after injection. Although K(1) estimated from graphical analysis was slightly smaller than that by NLS, there was strong correlation among the K(1) values obtained by these 3 methods. In the simulation study, for graphical analysis, the differences between the true and mean of K(1) estimates became larger and the coefficient of variation (COV) of K(1) estimates became smaller as the end time of linear regression became later. The COV of graphical analysis was almost equal to that of NLS with the 1-input compartment model. CONCLUSION: The transfer of (11)C-verapamil from plasma to the brain was able to be quantitatively estimated by graphical analysis because this method can provide K(1) from the data of the initial few minutes without considering the effect of the metabolites in plasma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Quantitative analysis of biological membrane lipids at the low picomole level by nano-electrospray ionization tandem mass spectrometry.

Nano-electrospray tandem mass spectrometry allows qualitative and quantitative analysis of complex membrane lipid mixtures at the subpicomole level. We have exploited this technique to selectively detect individual classes of phospholipids from unprocessed total cellular lipid extracts by either precursor ion or neutral loss scanning. This way phosphatidylcholine, sphingomyelin, phosphatidylinositol and -phosphates, phosphatidylethanolamine, phosphatidylserine, phosphatidylglycerol, phosphatidic acid, and their plasmalogen analogues can be detected. The optimized ionization and fragmentation conditions described together with the principle of internal standardization by nonnatural analogues allow the rapid and quantitative determination of membrane lipid compositions down to sample amounts of 1000 cells.

Animals↗
PubMedDate not supplied

Quantitative analysis of spermatogenic DNA synthesis in the rat using a monoclonal anti-5-bromodeoxyuridine antibody.

The utility of the 5-bromodeoxyuridine (BrdUrd) labelling technique for the quantitative analysis of spermatogenic deoxyribonucleic acid (DNA) synthesis was investigated in the rat. Rat testicles were labelled by a single intraperitoneal injection of 100 mg kg-1 of BrdUrd. The testicles were removed 1 h after injection, fixed in Bouin's fluid and embedded in paraffin. BrdUrd-labelled cells were detected by immunohistochemical staining using a monoclonal anti-BrdUrd antibody. The number of BrdUrd-labelled tubules per total number of tubules (percent L.T.), the number of BrdUrd-labelled cells per total number of tubules (tubular ratio) and the number of BrdUrd-labelled cells per number of Sertoli cells (Sertoli cell ratio in BrdUrd-labelled cells) were calculated as indices of spermatogenic DNA synthesis during each stage of the seminiferous epithelial wave. BrdUrd labelling was found exclusively in the nuclei of spermatogonia and in preleptotene spermatocytes in the seminiferous epithelium. The percent L.T. was generally greater than 50%, except in stages VI, VII and XIV, and the tubular as well as Sertoli cell ratios in BrdUrd-labelled cells was greater than 2.0 and 0.15, respectively, in stages I, II-III, V, VIII, X, and XII. The tubular ratio and Sertoli cell ratio in BrdUrd-labelled cells along the seminiferous epithelial wave had two distinct peaks. The distribution of the tubular ratio using the BrdUrd-labelling technique correlated well with the distribution previously established by measuring tritiated thymidine uptake per tubule. Thus, the BrdUrd labelling technique, which is more efficient than the tritiated thymidine labelling technique, can be used to quantitatively evaluate spermatogenic DNA synthesis.

Animals↗
PubMed1985

Meta-analysis: quantitative integration of independent research results.

Meta-analysis, a quantitative method of combining the results of independent research studies, is described as a method for reviewing research literature. Four steps are taken to summarize the research in an area. First, a thorough literature review is conducted to identify a group of research studies with the relevant treatment variable. Second, an effect size is calculated for each study. Third, an overall (composite) effect size is determined by a weighted combination of the obtained effect sizes. Fourth, a fail-safe N (the number of unpublished studies with opposing conclusions needed to negate the published literature) is calculated to assess the certainty of the overall effect size. Meta-analysis was applied to 33 studies of chymopapain in an illustrative example. The analysis produced a large effect size of 0.8082 and a fail-safe N of 214, indicating strong support for the effectiveness of the treatment with chymopapain. Meta-analysis can be a useful tool if it is used properly. It is particularly useful as an adjunct to other methods of review that are used in pharmacy practice.

Chymopapain↗
PubMed1996

Radioimagers as an alternative to film autoradiography for in situ quantitative analysis of 125I-ligand receptor binding and pharmacological studies.

Three radioimagers, the mu-imager, the beta-imager and the phosphorimager, were tested as alternatives to quantitative autoradiography on film, for receptor imaging and pharmacological in situ quantitative analysis. Two iodinated ligands 125I-interleukin-1 alpha and 125I-gonadotropin releasing hormone agonist were used for receptor characterization in mouse brain and pituitary sections. Due to the high number of the agonist receptors in rat pituitary gland, this tissue was used to compare measurements obtained from digital autoradiograms with classical gamma detector determination. This permits the evaluation of radioimager efficiency and absolute quantification. Radioimagers represent an improvement in terms of time of image acquisition. All the radioimagers are more sensitive than film for the detection of low levels of radioactivity. The spatial resolution provided by the mu-imager compares favourably with that obtained on film autoradiograms while digital autoradiograms from the phosphorimager and beta-imager did not show precise definition under our experimental conditions. Superimposition of histological structures from the stained sections with radiolabelled areas in the autoradiograms remains, at this time, the unique advantage of film. In conclusion, radioimagers represent an alternative to autoradiography on film or emulsion for in situ quantitative studies on tissue sections. They combine precise imaging for in situ binding studies with easy and direct access to counts in cpm. The improvement in radioimaging technology has, therefore, brought in situ analysis of iodinated ligand binding to the level of accuracy that is obtained with classical detectors of radioactivity.

Animals↗
PubMed2001

Quantitative analysis and molecular species fingerprinting of triacylglyceride molecular species directly from lipid extracts of biological samples by electrospray ionization tandem mass spectrometry.

Herein we describe a rapid, simple, and reliable method for the quantitative analysis and molecular species fingerprinting of triacylglycerides (TAG) directly from chloroform extracts of biological samples. Previous attempts at direct TAG quantitation by positive-ion electrospray ionization mass spectrometry (ESI/MS) were confounded by the presence of overlapping peaks from choline glycerophospholipids requiring chromatographic separation of lipid extracts prior to ESI/MS analyses. By exploiting the rapid loss of phosphocholine from choline glycerophospholipids, in conjunction with neutral-loss scanning for individual fatty acids, overlapping peaks in the ESI mass spectrum were deconvoluted generating a detailed molecular species fingerprint of individual TAG molecular species directly from chloroform extracts of biological samples. This method readily detects as little as 0.1 pmol of each TAG molecular species from chloroform extracts and is linear over a 1000-fold dynamic range. The sensitivity of individual TAG molecular species to ESI/MS/MS analyses correlated with the unsaturation index and inversely correlated with total aliphatic chain length of TAG. An algorithm was developed which identifies sensitivity factors, thereby allowing the rapid quantitation and molecular species fingerprinting of TAG molecular species directly from chloroform extracts of biological samples.

Animals↗
PubMed2004

Quantitative analysis of imazamox herbicide in environmental water samples by capillary electrophoresis electrospray ionization mass spectrometry.

Capillary electrophoresis-mass spectrometry (CE-MS) with an electrospray ionization interface was applied for the quantitative analysis of imazamox pesticide in well water, potable water, and pond water. The detector response for imazamox was determined to be linear over the concentration range of 50-1 ng/ml. The limits of quantitation and detection of the method were determined to be 200 and 20 ng/l for imazamox compound in each type of water sample, respectively. The total sample preparation and CE-MS analysis time was under 2 h.

Calibration↗