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 613 records · Page 34Linked to original sources
PubMed1995

A quantitative analysis of alternated line scanning in k space and its application in MRI of regional tissue perfusion by arterial spin labeling.

A quantitative analysis of the alternated-line-scanning method is performed for k-space data acquisition in MRI. Application of the method in MRI of regional tissue perfusion by arterial spin labeling is demonstrated. It is also shown that, by using the alternated-line-scanning method, the degree of arterial spin labeling alpha can be determined in a single scan.

Animals↗
PubMed1999

Qualitative and quantitative analysis of new alkyl amide arginine surfactants by high-performance liquid chromatography and capillary electrophoresis.

A protocol for the qualitative and quantitative analysis of novel arginine-based cationic surfactants using HPLC and CE was studied and compared. The optimization of the analytical conditions was carried out through a systematic variation of the experimental parameters such as mobile phase, eluent conditions, ion pairing and amount of sample for HPLC, and type of buffer, ion strength, type and amount of organic solvent, sample injection time, applied voltage and column washing and conditioning for CE.

Amides↗
PubMed1999

A solid-phase assay for quantitative analysis of sulfated glycosaminoglycans at the nanogram level. Application to tissue samples.

A sensitive and accurate solid-phase methodology for the quantitative analysis of glycosaminoglycans is described. Chondroitin-4-sulfate (CSA) was labelled with biotin hydrazide after the reaction of its carboxyl groups with it in the presence of carbodiimide. Polystyrene plates modified with sequential reaction with glutaraldehyde (GH) and spermine to possess amino groups were used to immobilize electrostatically the biotin labelled CSA. Exogenously added sulfated glycosaminoglycans (GAGS) [variously sulfated chondroitin sulfates and heparan sulfate (HS)] were found to compete to this immobilization in a concentration dependent mode, within a concentration range from 10 up to 300 ng/ml. Glycosaminoglycan-derived oligosaccharides competed to a degree similar to that of intact molecules. Hyaluronan (HA) and keratan sulfate (KS) did not compete the immobilization. The procedure was applied for the rapid and reproducible determination of the sulfated glycosaminoglycans in proteinase digests of small tissue samples or cell cultures with high sensitivity and accuracy.

Algorithms↗
PubMed2006

[Simultaneous quantitative analysis of three kinds of phenols by Elman recurrent neural network].

Elman recurrent neural network ( ERNN) was applied to study the simultaneous quantitative analysis of seriously overlapped spectra of a p-nitrophenol, o-nitrophenol and 2,4-dinitrophenol system. The multivariate linear regression (MLR) method was also applied in this study for comparison. Two programs (PERNN and PMLR) were designed to perform the calculations. By optimization, the structure and parameters of Elman recurrent neural network were defined. The relative standard errors of prediction (RSEP) for all components with ERNN and MLR were 3.1% and 2 027.3%, respectively. Experimental results showed the method to be successful even where there was a severe overlap of spectra. The ERNN method is a valuable tool in solving the minimum problem and improving the convergence rate, and can be used to analyze the whole spectra rather than just picking out a few characteristic values. The method provides a new way of simultaneous determination of severely overlapped molecular spectra without prior separation.

English Abstract↗
PubMedDate not supplied

Quantitative analysis of seminiferous epithelium in subfertile carriers of chromosomal translocations.

In order to study the effect of structural chromosomal aberrations on spermatogenesis, quantitative analysis of the germinal epithelium was performed on testicular specimens from 12 carriers of balanced chromosomal translocations diagnosed at male infertility clinics: a Y-autosome translocation, eight reciprocal translocations, and three D/D Robertsonian translocations. Spermatogenic arrest at the spermatocyte stage was revealed in the Y-autosome translocation and four of the reciprocal translocations. The number of spermatids was selectively reduced in three carriers, while normal spermatogenesis was found in three. Thus, the majority of carriers with impaired semen quality showed a complete or partial reduction in the number of spermatids, suggesting that the effect of chromosomal aberrations is to arrest the spermatogenic process at the spermatocyte stage.

Adult↗
PubMed1990

Quantitative analysis of smooth pursuit eye movements by personal computer. II. Evaluation of individual performance and clinical applicability.

In a previous report on quantitative analysis of smooth pursuit eye movements (SPEM) we assessed two equations in order to describe the SPEM gain/target velocity relationship, and we demonstrated that this relationship is age-related. This report presents a method to evaluate normality of a single subject SPEM performance. Three points have been considered: 1) The control of gain asymmetries depending on target direction (leftward vs rightward SPEM) 2) The definition of age-related control values 3) The subject vs control values comparison An example to explain how our method actually works and its clinical applicability is shown. Finally, the reasons why no choice has been made between the two equations are discussed.

Age Factors↗
PubMed1988

Regression of atherosclerosis in normotensive and hypertensive rabbits. A quantitative analysis of cholesterol-induced aortic and coronary lesions with an image-processing system.

In the present study we attempted to quantitate the sequential changes occurring in cholesterol-induced aortic and coronary lesions in normotensive and ronovascular hypertensive rabbits, which were placed on a 0.5% cholesterol atherogenic diet for 16 weeks and observed for up to 104 months after withdrawal of the diet. After measuring the degree of surface involvement, a representative longitudinal section covering the whole length of the aorta was obtained, and histometric quantitative analysis was carried out using an image-processing system. Furthermore, ten continuous step-sections of the left coronary artery bed were prepared from each animal, and the degrees of luminal stenosis were estimated in all arterial segments contained. After withdrawal of the cholesterol diet, foam cell lesions of the aorta and coronary artery were gradually replaced by fibromuscular tissue. The hypertensive animals showed a greater degree of smooth muscle cell proliferation. Formation of atheroma occurred almost invariably after cessation of cholesterol feeding, and it was noted that hypertension aggravated the severity and extent of both aortic and coronary atherosclerosis. Upon histometric analysis, evidence of reduction of aortic lesions and significant reversal of luminal narrowing of the coronary artery were observed in normotensive as well as hypertensive animals. These results suggest that, even in hypertensive animals, substantial regression of both aortic and coronary atherosclerosis can be expected after normalization of hypercholesterolemia.

Animals↗
PubMed1991

Quantitative analysis of the active tablet ingredient by powder X-ray diffractometry.

A powder X-ray diffraction technique has been developed for the quantitative analysis of the active ingredient in intact tablets. Two model drugs were used: lithium carbonate (LC) and carbamazepine (CBZ). Mixtures containing various weight fractions of each drug and microcrystalline cellulose were compressed into tablets and the integrated intensities of several diffraction lines of each were used for quantitative purposes. The ratio of the integrated intensity of these lines in tablets, made from mixtures of drug and microcrystalline cellulose, to the intensity of the same lines in tablets made from only drug was calculated as a function of the weight fraction of the drug in the mixture. These ratios were also experimentally determined and the relative error in the determination of LC was less than 12%. CBZ tablets containing starch were also prepared. In the CBZ tablets containing microcrystalline cellulose or starch, the relative error in the determination of CBZ was less than 10% only when the weight fraction of CBZ in the tablets was greater than or equal to 0.4.

Antiviral Agents↗
PubMed1988

Liquid chromatographic procedure for the quantitative analysis of carboplatin in beagle dog plasma ultrafiltrate.

A specific and reproducible high-performance liquid chromatographic (HPLC) procedure was developed for the quantitative analysis of carboplatin (JM-8) in dog plasma ultrafiltrate. Plasma ultrafiltrate samples were generated using Amicon Centrifree micropartition systems or Amicon Centriflo cones, and injected onto a microBondapak NH2 column. The mobile phase consisted of acetonitrile:methanol:0.005 M sodium perchlorate, pH 2.4 (77-75:13-15:10, v/v/v); the flow rate was 1.5 mL/min. Detection was performed by monitoring UV absorbance of the column effluent at 229 nm. Carboplatin eluted between 9.5 and 11.0 min. The internal standard, JM-10, eluted between 11.0 and 13.0 min. The peak height ratio of carboplatin:internal standard versus carboplatin concentration was linear over a range of 0.2 to 20.0 micrograms/mL. The limit of quantitation was 0.2 microgram/mL. The intra-assay precision of this method, as measured by percent relative standard deviation (%RSD), was within 12% for the theoretical concentrations 0.5, 5.0, and 50.0 micrograms/mL. Accuracies were within 11%. The results of the validation procedures indicated that this procedure was accurate and specific.

Animals↗
PubMed2005

An integrated mass spectrometry-based proteomic approach: quantitative analysis of tandem affinity-purified in vivo cross-linked protein complexes (QTAX) to decipher the 26 S proteasome-interacting network.

We developed an integrated proteomic approach to decipher in vivo protein-protein interactions and applied this strategy to globally map the 26 S proteasome interaction network in yeast. We termed this approach QTAX for quantitative analysis of tandem affinity purified in vivo cross-linked (X) protein complexes. For this work, in vivo formaldehyde cross-linking was used to freeze both stable and transient interactions occurring in intact cells prior to lysis. To isolate cross-linked protein complexes with high purification efficiency under fully denaturing conditions, a new tandem affinity tag consisting of a hexahistidine sequence and an in vivo biotinylation signal was adopted for affinity-based purification. Tandem affinity purification after in vivo cross-linking was combined with tandem mass spectrometry coupled with a quantitative SILAC (stable isotope labeling of amino acids in cell culture) strategy to carry out unambiguous protein identification and quantification of specific protein interactions. Using this method, we captured and identified the full composition of yeast 26 S proteasome complex as well as the two known ubiquitin receptors, Rad23 and Dsk2. Quantitative mass spectrometry analysis allowed us to distinguish specific proteasome-interacting proteins (PIPs) from background proteins and led to the identification of a total of 64 potential PIPs of which 42 are novel interactions. Among the 64 putative specific PIPs, there are ubiquitin pathway components, ubiquitinated substrates, chaperones, and transcription and translation regulators, demonstrating the efficacy of the developed approach in capturing in vivo protein interactions. The method offers an advanced technical approach to elucidate the dynamic protein interaction networks of the proteasome and can find a wide range of applications in the studies of other macromolecular protein complex interaction networks.

Amino Acid Sequence↗
PubMed1992

Quantitative analysis of Langerhans' cells in epidermis at irritant contact reactions using confocal laser scanning microscopy.

Confocal laser scanning microscopy (CLSM) was used for quantitative analysis of CD1a+ cells in epidermis at irritant reactions. Sodium lauryl sulphate (2% and 4%) or non-anoic acid (20% and 80%) were applied to the skin of healthy volunteers under occlusion for 24 h. Skin biopsy specimens were taken after additional 24 h and were snap frozen. Freeze-sections, 25 microns thick, were stained with anti-CD1a antibodies (Leu-6) followed by FITC-labelled rabbit anti-mouse IgG. The sections were viewed and optically sectioned in the CLSM at four depth levels. The data was analysed using a threshold value for the fluorescence. The obtained result is presented as the proportion of specimen area having a fluorescence intensity above the threshold. The result demonstrates that the CLSM is a useful tool for obtaining not only structural information but also quantitative information from a defined tissue volume. In the present investigation it was possible to demonstrate variations in CD1a+ reactivity in epidermis at detergent-induced irritant reactions with a marked decrease in CD1a+ after 80% non-anoic acid exposure and only minor differences in the CD1a+ after 2% and 4% sodium lauryl sulphate exposure.

Cell Count↗
PubMed1994

Quantitative analysis of CD34+ stem cells using RT-PCR on whole cells.

We have employed RT-PCR of whole cells to develop a quantitative method for estimating the number of rare cells expressing a unique mRNA in a large, mixed population of cells. We have demonstrated that RT-PCR can be done on whole cells without the need for extraction of the RNA. This allows for a great saving of time and effort, as well as allowing quantitative analysis to be based on the total number of cells analyzed in a given aliquot and the presence or absence of the specific RT-PCR product. We have employed a limiting dilution series on whole cells, with multiple aliquots at each cell concentration to achieve more statistical power in the analysis of a rare cell type. We have used a nested amplification of the CD34 mRNA to be able to detect a single cell expressing the CD34 mRNA in a larger population of non-CD34-expressing cells. We demonstrate that by using this technique, cells from blood and bone marrow containing the CD34 mRNA can be followed quantitatively during a multistep purification involving immunoadsorption followed by fluorescence-activated cell sorting. We also demonstrate that many cells that express the CD34 protein on their surface no longer contain detectable levels of CD34 mRNA, a phenomenon that appears to be developmentally regulated.

Antigens, CD↗
PubMed2000

Quantitative analysis of EEG background activity in patients with rolandic spikes.

OBJECTIVE: The aim was to compare the background activity, through quantitative EEG analysis, of patients with rolandic spikes and normal age-matched controls. MATERIAL AND METHODS: Twenty-one channel EEG of 23 children with rolandic spikes and 39 normal children, with ages ranging from 7 to 12 years, were submitted to quantitative analysis (FFT) of discharge-free epochs. Patients and controls were divided in groups according to age (7-9 and 10-12 years old). Delta, theta, alpha and beta frequency ranges were compared between groups for all electrode positions. RESULTS: Comparing normals, the 7-9 years old group showed power reduction in the alpha and beta ranges. Comparing patients and normal age-matched groups, the patients showed power increase, at all frequency ranges in the 7-9 years old group and at delta and theta frequency ranges in the 10-12 years old group. CONCLUSIONS: Our findings agree with recent evidences that these children may differ from normal (besides the eventual occurrence of seizures); but they also suggest that these differences can be related to immaturity and not necessarily related to the epileptiform discharge.

Brain↗
PubMed2004

Microwave-assisted extraction and quantitative analysis of high-density polyethylene pellets fortified with flavors.

Microwave-assisted extraction (MAE) has been shown to be an easy, rapid, accurate, quantitative, and precise component of an overall method for the quantitative analysis of flavor components formulated into high-density polyethylene (HDPE) pellets. Under optimized extraction conditions, MAE can be perform extraction of flavors from pellets within 1/2 h with flavor recoveries ranging from approximately 90% to 100%. The variability in the data expressed as percent relative standard deviation from gas chromatographic-mass selective detector analysis of targeted flavor components is always less than 5%, indicating a precise method. In addition, the major components identified in the flavor formulation prior to formulation into the HDPE pellets are the major components detected in the extraction, indicating an accurate determination. Thus, MAE can be readily recommended as an essential component of a high-volume approach to the quantitative determination of flavors formulated into HDPE pellets.

Flavoring Agents↗
PubMed1982

A continuous and quantitative analysis of the uneven distribution of myocardial blood flow in dogs using a distribution function of the clearance time constant.

A continuous and quantitative analysis of the uneven distribution of coronary blood flow was accomplished in anesthetized open-chest dogs using the distribution function of the hydrogen (H2) clearance time constant. The distribution function was derived by analysing the H2 washout curves in the coronary sinus which were obtained by the H2 clearance method, using platinum electrodes placed in the coronary sinus. Twelve to seventeen platinum electrodes were employed to obtain simultaneous measurements of the regional myocardial flow before and after stenosis of the left anterior descending coronary artery. Theoretically, the H2 washout curves in the coronary sinus could be interpreted as a function with multi-exponential characteristics, represented by an equation similar to the Laplace transform of the distribution function of the H2 clearance time constant. Therefore, we assumed that such an equation would represent the uneven distribution of coronary blood. We obtained the distribution function by using an approximation method to solve the integral equation and we employed digital computation to increase the resolution. Before stenosis of the left anterior descending coronary artery, the log distribution function curves with respect to the H2 clearance time constant were roughly symmetrical in terms of the maximum peak in the time constant. After stenosis of the left anterior descending coronary artery, the log distribution function had two peaks and the range of distribution was much larger than that before coronary stenosis. Our findings may prove to be valuable as a technique to estimate continuously and quantitatively the heterogeneous distribution of myocardial blood flow.

Animals↗
PubMed1994

[Quantitative analysis of 123I-metaiodobenzylguanidine myocardial imaging: assessment of its usefulness in patients with congestive heart failure].

To investigate the usefulness of the quantitative analysis of 123I-metaiodobenzylguanidine (123I-MIBG) myocardial uptake, we studied 9 normal subjects and 18 patients with congestive heart failure (CHF). Rest myocardial imaging with 123I-MIBG was performed at 20 minutes and 3 hours (delayed image) after 123I-MIBG injection. Rest 201Tl imaging was obtained at 20 minutes after 201Tl injection. In addition to ordinary tomograms, a planar anterior image and a whole body image were supplemented in each imaging. In patients with CHF fractional shortening (%FS) was calculated from echocardiography and left ventricular ejection fraction was obtained from cardiac blood pool imaging with 99mTc at rest. We calculated H/M (heart to mediastinum count ratio) from the anterior planar image and %Uptake (percentage of cardiac uptake of the isotope to total injected dose) from the whole body image. H/M of 123I-MIBG in delayed images separated patients with CHF from normal subjects (2.00 +/- 0.19 vs. 2.56 +/- 0.13, p < 0.01). H/M Ratio (H/M of 123I-MIBG divided by H/M of 201Tl) in delayed image could distinguish these two groups poorly (0.72 +/- 0.12 vs. 0.88 +/- 0.14, p < 0.05). On the other hand, %Uptake of 123I-MIBG was not different between two groups (3.49 +/- 0.60% in CHF, 3.54 +/- 0.34% in normal). But %Uptake of 201Tl was greater in CHF than in normal (5.96 +/- 1.09% vs. 4.70 +/- 0.30%, p < 0.05). When myocardial 123I-MIBG uptake was normalized by myocardial perfusion (%Uptake of 123I-MIBG divided by %Uptake of 201Tl, Uptake Ratio), Uptake Ratio in delayed image could distinguish theses two groups as same as H/M (0.60 +/- 0.05 in CHF, 0.75 +/- 0.05 in normal, p < 0.01). In patients with CHF, H/M of 123I-MIBG did not reflect LV function and serum norepinephrine (NE) level. But Uptake Ratio and H/M Ratio in delayed image correlated well with %FS (r = 0.88, r = 0.65), EF (r = 0.80, r = 0.68) and NE level (r = -0.77, r = -0.75). Although the calculation of Uptake Ratio is time consuming and expensive, it was assumed that Uptake Ratio is an useful index to quantitate myocardial 123I-MIBG uptake.

3-Iodobenzylguanidine↗
PubMed2005

Colorimetric assays for quantitative analysis and screening of epoxide hydrolase activity.

Focusing on directed evolution to tailor enzymes as usable biocatalysts for fine chemistry, we have studied in detail several colorimetric assays for quantitative analysis of epoxide hydrolase (EH) activity. In particular, two assays have been optimized to characterize variants issued from the directed evolution of the EH from Aspergillus niger. Assays described in this paper are sufficiently reliable for quantitative screening of EH activity in microtiter plates and are low cost alternatives to GC or MS analysis. Moreover, they are usable for various epoxides and not restricted to a type of substrate, such as those amenable to assay by UV absorbancy. They can be used to assay EH activity on any epoxide and to directly assay enantioselectivity when both (R) and (S) substrates are available. The advantages and drawbacks of these two methods to assay EH activity of a large number of natural samples are summarized.

Aspergillus niger↗