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PubMed1994

Quantitative analysis of the surface morphology and textile structure of the polyurethane Vascugraft arterial prosthesis using image and statistical analyses.

The surface morphology and textile structure of the Vascugraft polyurethane arterial prosthesis were investigated. Novel methods of image analysis and the presentation of statistical data were used to obtain quantitative results of the surface morphology of the non-woven microfibrous structure of prostheses of three different sizes. These techniques have identified apparent differences in the distributions of thickness and orientation of the microfibres between the internal and external surfaces and between the three prostheses investigated.

Biocompatible Materials↗
PubMed2006

A quantitative analysis of Arabidopsis plasma membrane using trypsin-catalyzed (18)O labeling.

Typical mass spectrometry-based protein lists from purified fractions are confounded by the absence of tools for evaluating contaminants. In this report, we compare the results of a standard survey experiment using an ion trap mass spectrometer with those obtained using dual isotope labeling and a Q-TOF mass spectrometer to quantify the degree of enrichment of proteins in purified subcellular fractions of Arabidopsis plasma membrane. Incorporation of a stable isotope, either H(2)(18)O or H(2)(16)O, during trypsinization allowed relative quantification of the degree of enrichment of proteins within membranes after phase partitioning with polyethylene glycol/dextran mixtures. The ratios allowed the quantification of 174 membrane-associated proteins with 70 showing plasma membrane enrichment equal to or greater than ATP-dependent proton pumps, canonical plasma membrane proteins. Enriched proteins included several hallmark plasma membrane proteins, such as H(+)-ATPases, aquaporins, receptor-like kinases, and various transporters, as well as a number of proteins with unknown functions. Most importantly, a comparison of the datasets from a sequencing "survey" analysis using the ion trap mass spectrometer with that from the quantitative dual isotope labeling ratio method indicates that as many as one-fourth of the putative survey identifications are biological contaminants rather than bona fide plasma membrane proteins.

Arabidopsis Proteins↗
PubMed2003

Atmospheric pressure electrospray ionization mass spectra of glucose and 2-fluorodeoxyglucose for quantitative analysis of 2-fluorodeoxyglucose by high-performance liquid chromatography.

2-Fluoro-2-deoxy-D-glucose (FDG) labeled by fluorine-18 is the most widely used radiopharmaceutical for positron emission tomography (PET). For high-performance liquid chromatography (HPLC)/MS assay and quality control, the mass spectra of FDG and glucose (Glc) in organic + water solutions were studied by flow injection analysis (FIA) and in a chromatographic eluate. In acetonitrile (MeCN) + 0.025% ammonium formate (NH(4)HCO(2)) solvent (80 : 20), electrospray ionisation (ESI) of glucose-FDG provides M.NH(4)(+) and 2M.Na(+) (M = Glc or FDG) as the most intense positive ions. Formation of the latter ions and also of M.MeCN.Na(+) and 2MeCN. Na(+) is typical of the presence of NaCl in the ESI inlet. The positive ions include heavier ions corresponding to the impurities separated by HPLC and also to the cross-ring fragmentation of complexes (2FDG. aMeCNX)L, where a = 0 or 1, L is either Na(+) or NH(4)(+) and X is a fragmented pyranose or anhydropyranose residue. The second most abundant Glc negative ion is m/z = 359 which was interpreted as (2GlcH(+))(). The negative-ion spectrum of FDG has dominating lines due to FDG.HCO(2)() ions at m/z 227 and also (2FDGH(+))() at m/z 363. The m/z 363 signal is suppressed in the presence of NaCl at a molar ratio of 4 : 1 to NH(4)HCO(2), while the ions at m/z 217 and 219, i.e. FDG.Cl(), become three times more intense than FDG.HCO(2)(). The latter ion appears to be most suitable as an analytical signal for chemical analysis of FDG at m/z 226 and 227. Limits of FDG quantitation (LOQ) of 19 ng and 21 ng were found for the 200(+) and 227() ion signals, respectively, and are wholly adequate for verification of total FDG content in radiopharmaceuticals.

Atmospheric Pressure↗
PubMed2005

Quantitative analysis of docetaxel in human plasma using liquid chromatography coupled with tandem mass spectrometry.

An assay for the quantitative determination of docetaxel in human plasma is described. Docetaxel was extracted from the matrix using liquid-liquid extraction with ter-butylmethylether, followed by high-performance liquid chromatographic analysis using an alkaline eluent. Paclitaxel was used as internal standard. Positive ionization electrospray tandem mass spectrometry was performed for selective and sensitive detection. The method was validated according to the FDA guidelines on bioanalytical method validation. The validated range for docetaxel was from 0.25--1000 ng/mL using 200 microL plasma aliquots. The method requires only a limited volume (200 microL) of human plasma and the method can be applied in studies requiring a low lower limit of quantitation of 0.25 ng/mL. The assay was applied successfully in several clinical and pharmacological studies with docetaxel.

Administration, Oral↗
PubMed2000

Quantitative analysis of cell division in leaves: methods, developmental patterns and effects of environmental conditions.

In planta quantitative studies of cell cycle are necessary for examining the role of cell division in the response of plants to environmental conditions and to analyse the behaviour of transformed plants in this context. We present and discuss non-intrusive kinematic methods which allow estimating the duration of cell cycle with a high spatial resolution in the leaf. Different methods are proposed and discussed for monocotyledons and dicotyledons, and compared with methods involving the use of chemicals. In monocotyledon leaves, cell division is restricted to a limited zone near the leaf insertion point, twice as long in the mesophyll as in the epidermis. In dicotyledons, cell division occurs in the whole leaf with a uniform and constant cell cycle duration for a determinate number of cell cycles, representing about half of leaf development. Over several experiments, this number is well conserved in a given leaf zone in the absence of stresses, but larger near the leaf base than near the leaf tip. After that, cell cycle duration increases because cells are progressively blocked in G1 while the durations of S-G2-M phases do not change with time. Leaf temperature affects neither the distribution of nuclei in each phase of the cycle nor the number of cell cycles in a leaf. Water or light deficits both cause a partial blockage of nuclei in G1 during the stress only, thereby increasing cell cycle duration and decreasing final cell number. These results suggest that a strong developmental programme drives cell division in leaves, so a simple framework allows analysis of temporal patterns, of spatial gradients and of the effect of environmental conditions.

Biomechanical Phenomena↗
PubMed2000

Quantitative analysis of the effect of near lens addition on accommodation and myopigenesis.

PURPOSE: To develop a quantitative, objective, and scientific basis for understanding the effects of applying near bifocal additions (ADDs) on oculomotor control and myopia development. This is important because myopia is a major public health problem that affects 25% of the U.S. population and 75% or more in Asian countries. It is also associated with an increased risk for vision-threatening conditions, such as retinal breaks and detachments, as well as glaucoma. METHODS: A comprehensive model of refractive error development was constructed based on a dual-interactive feedback model of accommodation and vergence, which represented the short-term dynamics pathway, with the addition of both genetic and environmental (defocus-induced axial growth) components in a long-term pathway. An alternating near- and far-viewing paradigm was simulated, with varying amounts of ADDs, to obtain a parametric relationship between the root mean square of accommodative error (AE) and the induced refractive error (IRE). The parametric relationship provided the crucial linkage between the long-term growth pathway and the conventional short-term dynamics pathway. ADD is the simulated lens placed before the eyes only during near viewing, whereas IRE is the simulated lens fixed before the eyes that represents the optical effect of slowly progressive refractive development caused by near work. RESULTS: A V-shaped functional relationship was found between AE and IRE. The left half of the curve is associated with hyperopic defocus and myopigenesis, whereas the right half is associated with myopic defocus and hyperogenesis. Introduction of an ADD shifts the V-shaped curve horizontally. Thus, an "optimal" ADD can be used to shift the minimum of the accommodative error curve to the zero IRE point, and thereby reduce or eliminate retinal defocus and its potential towards myopigenesis. On the other hand, sensitivity analysis of model parameters shows that increasing the accommodative convergence crosslink gain (AC) shifts the curve to the right and results in a tendency towards myopigenesis, which is consistent with clinical findings in progressive myopia. CONCLUSIONS: The model can be used to specify the precise ADD needed for an individual to retard or eliminate retinal defocus-induced myopic progression. If future experiments show that using the "optimal" ADD results in the greatest benefit (i.e., least myopia progression), there will be considerable worldwide public health benefit.

Accommodation, Ocular↗
PubMed1999

Visual field defects after temporal lobe resection: a prospective quantitative analysis.

OBJECTIVE: To evaluate and quantify prospectively visual field changes in patients undergoing temporal lobe resections for intractable epilepsy. BACKGROUND: Visual field abnormalities occur after temporal lobe resections for epilepsy; however, we have not encountered published reports using automated static visual field analysis. METHODS: Humphrey visual fields (program 30-2) were obtained before and after partial temporal lobe resection in 32 consecutive patients with intractable epilepsy. A quantitative point-by-point analysis was made in the affected superior quadrant, and the defects were averaged for the whole patient group. RESULTS: Thirty-one patients developed a visual field defect, but none was aware of the defect. The points nearest fixation were relatively spared. The defects were greatest in the sector closest to the vertical meridian in the eye ipsilateral to the resection. The ipsilateral and contralateral mean field defects also differed in both topography and depth. A significant correlation was found between the extent of lateral temporal lobe resection and the degree of the defect in the contralateral eye. CONCLUSIONS: There are differences in the shape and depth of the ipsilateral and the contralateral field defects not previously reported. These findings demonstrate that certain fibers from the ipsilateral eye travel more anteriorly and laterally in Meyer's loop, and support the hypothesis that visual field defects due to anterior retrogeniculate lesions are relatively incongruous because of anatomic differences in the afferent pathways. Automated perimetry is a sensitive method of evaluating and quantifying visual field defects.

Adolescent↗
PubMed1989

Quantitative analysis of platelet activating factor using fast atom bombardment/tandem mass spectrometry.

A procedure is described for the quantitative determination of platelet activating factor (PAF) using stable isotope dilution and fast atom bombardment/tandem mass spectrometry. Low-energy collisional activation of the [M + H]+ ion of PAF yields a single daughter ion of m/z 184, characteristic of phosphocholine derivatives. For precise and accurate quantification, the internal standard is (2H3)acetyl-hexadecyl PAF, which yields an analogous daughter ion of m/z 185. Quantitative analyses are based on limited mass-range parent ion scanning with transmission of daughters of m/z 184 and 185 during alternate scans; all scans are accumulated into a single data file to facilitate determination of the analyte/internal standard response ratio. Analysis of authentic hexadecyl PAF indicates a low-picogram detection limit. The method has been applied to the determination of PAF in preparations of human neutrophils stimulated by addition of a calcium ionophore. Concentrations of PAF of 7-17 ng/10(6) cells were observed, in keeping with earlier reports. The method has been validated by standard addition and dilution experiments. Comparison of data obtained by the new procedure and those obtained by a method involving gas chromatography/electron capture mass spectrometry of dephosphorylated and derivatized PAF showed excellent agreement.

Calcimycin↗
PubMed2004

Qualitative and quantitative analysis of amino acids by capillary electrophoresis-electrospray ionization-tandem mass spectrometry.

We describe a method to identify and quantify amino acids using capillary electrophoresis-electrospray ionization-triple-quadrupole tandem mass spectrometry (CE-ESI-MS/MS). Amino acids, including physiological amino acids, were first separated by CE under acidic pH conditions and then detected by MS/MS. To efficiently introduce the whole sample into the capillary, no electrical potential was applied to the electrospray probe until running electrophoresis. The position of the electrosprayer with respect to the MS capillary entrance drastically affected sensitivity and generation of cluster ions. MS/MS with multiple reaction monitoring (MRM) detection was performed to obtain sufficient selectivity and sensitivity. Under optimized CE-MS/MS conditions, the minimum detectable levels for 32 free amino acids normally found in proteins and other physiological amino acids were between 0.1 and 14 micromol/L with pressure injection of 50 mbar for 3 s (3 nL) at a signal-to-noise ratio of 3. For most amino acids, this constitutes a severalfold increase in sensitivity compared to CE-MS. The relative standard deviations (% RSD) for all amino acids were better than 0.4% for migration times and between 1.4% and 8.6% for peak areas (n = 10). Since amino acids exhibited characteristic MS/MS spectra, this approach is useful for the simultaneous, selective, quantitative, and reproducible analysis of amino acids in physiological and biological samples that contain various kinds of matrices. The power of the method was demonstrated by analyzing amino acids in human urine.

Amino Acids↗
PubMed1997

Quantitative analysis of the plain radiographic appearance of Ewing's sarcoma of bone.

RATIONALE AND OBJECTIVES: The authors quantitate the radiographic features that distinguish the plain radiographic appearance of Ewing's sarcoma (ES) from other solitary lesions of bone. METHODS: A total of 709 cases of focal bone lesions, including 44 ES, were analyzed according to demographic, anatomic, and plain radiographic features. Vector analysis of groups of features was performed to determine those that are most sensitive and specific for the appearance of ES in contrast with other lesions in the database. RESULTS: In our sample, Ewing's sarcoma is most consistently a medullary-based (91%) lytic (89%) lesion with at least a partially permeative appearance (82%), poorly defined edges (82%), no margination (91%), and a soft-tissue mass (61%). When these lesions occur in long bones, they most commonly are found in the diaphysis (75%) and are proximal more often than distal. Vector analysis suggests that any primary bone lesion without radiographically visible matrix and with either a soft-tissue mass, an appearance of permeative destruction alone or in combination with other patterns of bone destruction is suspect for the diagnosis. This small subset of common features appears to have a high sensitivity (89%) and prevalence (47%) of ES among the lesions meeting these criteria. Limiting the age of the patients to progressively younger age groups increases the specificity but lowers sensitivity. The vector analysis-generated differential diagnoses includes osteosarcoma, giant-cell tumor, lymphoma, and chondrosarcoma. CONCLUSIONS: A relatively specific set of radiographic features can be defined, which will assist in the radiographic diagnosis of ES and improve upon current textbook descriptions.

Adolescent↗
PubMed1981

Using a battery of tests to predict suicide in a long-term hospital: a quantitative analysis.

Examined the Wechsler-Bellevue, Rorschach, TAT and Word Association Tests of 40 Patients for quantitative indications of suicide potential. Ten of these patients had completed suicide, 10 "serious" attempts, 10 "mild" attempts and 10 had never made a suicide attempt. In addition to a study of the quantification of major aspects of the tests, various published hypotheses also were examined. No quantitative aspect of the data differentiated all four groups. When the "completed" and "serious" attempters were compared to the "mild" and "no" attempters, the more lethal patients were found to give more movement responses and more total responses. Those who completed suicide also had a larger difference than others between their Verbal and Performance IQs. Of the published hypotheses, only the Roth & Blatt and Sapolsky hypotheses received significant support.

Hospitals, Psychiatric↗
PubMed1996

Quantitative analysis of multiple V-region interactions among normal human IgG.

There is to date no quantitative method for scoring putative V-region interactions among serum antibodies, and the available qualitative techniques are not amenable to routine utilization. This deficit may explain the paucity of observations on the characteristics of the immune network, in contrast with the multiplicity of phenomenological descriptions on idiotype regulation. We describe here a novel methodology that uses isoelectric focusing (IEF) to resolve human F(ab')2 preparations from large pools of normal serum IgG into multiple bands, and computer-aided data processing to analyze interactions between the resulting blotted proteins and normal serum IgG from individual donors. Our results show that in all normal human sera tested, there are IgG-mediated interactions with a large number of IEF fractions of human F(ab')2. These interactions are V region specific, as assessed by inhibition experiments and by lack of binding of IgG monoclonal antibodies, and are characterized by average affinities that are in the micromolar range, as measured by surface plasmon resonance.

Antibody Affinity↗
PubMed1994

Repeated CT examinations in limited volume irradiation of brain tumors: quantitative analysis of individualized (CT-based) treatment plans.

Deviations of the position of the isocenter were quantitatively assessed for CT-based limited volume irradiation of brain tumors. Of the linear deviations, 95% were within 10 mm and 3 mm during treatment planning and delivery, respectively. The application of face masks before CT planning improved the accuracy of field alignment. Repeated CT examinations seemed to be more important after simulation than during treatment delivery.

Brain Neoplasms↗
PubMedDate not supplied

Development of corticospinal tract fibers and their plasticity I: quantitative analysis of the developing corticospinal tract in mice.

This study was undertaken to elucidate ultrastructurally and quantitatively the development of the corticospinal tract (CST) axons of mouse at the intumescence level of the cervical cord. An anterograde HRP study showed that the CST was located at the ventral one-third of the dorsal funiculus, and a few HRP-positive fibers were noted at the medialmost part of the ipsilateral anterior funiculus. Ultrastructurally, the CST was composed of unmyelinated axons, growth cones and a few degenerating axons until postnatal day 10 (P10), then the axons in CST gradually increased in size. The number of axons constituting the right CST was calculated at different days of age. The total numbers of axons at P0, P4, P14, P21 and P56 were 2.3 x 10(4), 6.2 x 10(4), 10.4 x 10(4), 7.1 x 10(4) and 3.5 x 10(4), respectively. These results indicate that the number of CST axons at the cervical intumescence of mouse becomes maximum at P14, and then decreases rapidly to reach the adult level of 3.5 x 10(4) (at P56), about 68% of them thus being lost.

Animals↗
PubMed2005

A novel enzyme-linked immunosorbent assay system for the quantitative analysis of Carassius auratus vitellogenin.

A sandwich enzyme-linked immunosorbent assay (ELISA) was developed to quantitatively detect Carassius auratus vitellogenin (VTG) levels. The protein levels in fish plasma are useful aquatic biomarkers of estrogenic compounds. This procedure involved an ELISA using monoclonal antibodies of CVmA2 and CVmA7 against Carassius auratus VTG, and CVmA7 conjugated to horseradish peroxidase as the detection antibody. The assay range was between 1 and 401.5 ng/ml and the recovery of the VTG added to Carassius auratus plasma was 92.5-109%. An in vitro assay was performed to measure low levels of the VTG, using primary hepatocytes of Carassius auratus induced by 17-beta estradiol (E2). The detection limit was 1 ng/ml and 137 ng/ml at the maximum. Within each sex of wild Carassius auratus, VTG levels from the river next to sewage treatment works (STWs) were much higher than those from the feeding stream. The Carassius auratus VTG bioassay could be a sensitive and useful tool for quantification of estrogenic principles in aquatic environments.

Animals↗
PubMed2006

The quantitative analysis of drug-receptor interactions: a short history.

Pharmacology started to develop into a real quantitative science in 1909, when A.V. Hill derived the Langmuir equation in the course of his studies on nicotine and curare. A history of the developments since then shows both brilliant insights and missed opportunities. It also shows that much remains to be done. There is still no mathematical description that can describe quantitatively the actions of agonists on G-protein-coupled receptors, although progress has been greater with agonist-activated ion channels, which are much simpler.

Animals↗
PubMed1989

Quantitative analysis of low molecular weight polar compounds by continuous flow liquid secondary ion tandem mass spectrometry.

Quantitative analyses of low molecular weight (100-200) polar compounds [1-methyl-4-phenylpyridine (MPP+), 2-amino-3-(methylamino)propanoic acid (synonyms, beta-(methyl-amino)-L-alanine or BMAA), and tryptophan] were conducted on a triple-stage quadrupole mass spectrometer configured for continuous flow liquid secondary ion mass spectrometry ionization (CF L-SIMS). It is shown that quantification by CF L-SIMS at subnanogram sensitivity can be precise (correlation coefficients greater than 0.99), accurate, specific, and routine for compounds not measurable by static L-SIMS. Successful analyses, however, are strongly dependent upon the stability of the film formed by the mobile phase on the probe tip. In our system, film stability is affected by mobile phase composition and flow rate, ion source and probe tip temperature, probe-tip and capillary alignment, film thickness, and sample composition.

1-Methyl-4-phenylpyridinium↗
PubMed2003

Quantitative analysis of synthetic polymers using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Quantitative analyses of synthetic polymers were accomplished using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS). Many factors have hindered the development of quantitative measurement of polymers via MALDI TOF MS, e.g., laser power, matrix, cation salt, and cocrystallization. By probing the optimal conditions, two sets of polymers were studied. Fair repeatability of the samples ensures acceptable results. In set 1, two poly(ethylene glycols) with different end groups showed equal desorption/ionization efficiencies. Two synthetic polymers in set 2 with different chemical properties resulted in different MALDI responses. Good linearity was achieved by plotting the relationship between the sample concentration ratio and the total signal intensity ratio in both sets.

Journal Article↗