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PubMed2001

Stable isotope dilution negative ion chemical ionization gas chromatography-mass spectrometry for the quantitative analysis of paroxetine in human plasma.

A sensitive and specific method for the quantitative determination of paroxetine in human plasma is presented. After solvent extraction from plasma with hexane/ethyl acetate (1 : 1) at alkaline pH and derivatization to the pentafluorobenzyl carbamate derivative, paroxetine was measured by gas chromatography-negative ion chemical ionization mass spectrometry. The carboxylate anion at m/z 372 was obtained at high relative abundance. [2H6]-labeled paroxetine was used as an internal standard and its rapid and facile preparation from the unlabeled compound is described. Calibration graphs were linear within a range of 0.094-12.000 ng x ml(-1) using 1 ml of plasma and 0.469-60 ng x ml(-1) using 200 microl of plasma. Intra-day precision was 1.47% (0.375 ng x ml(-1)), 3.16% (3 ng x ml(-1)) and 1.37% (9 ng x ml(-1)) for the low-level method, and 3.37% (1.875 ng x ml(-1)), 2.72% (15 ng x ml(-1)) and 2.22% (45 ng x ml(-1)) for the high-level method. Inter-day precision was 1.65% (0.375 ng x ml(-1)), 2.13% (3 ng x ml(-1)) and 1.66% (9 ng x ml(-1)) for the low-level method, and 1.10% (1.875 ng x ml(-1)), 1.56% (15 ng x ml(-1)) and 1.90% (45 ng x ml(-1)) for the high-level method. At the limit of quantification (0.094 ng x ml(-1)), intra-day precision was 4.30% (low-level method) and 2.56% (high-level method), and inter-day precision was 3.23% (low-level method) and 3.00% (high-level method). The method is rugged, rapid and robust and has been applied to the batch analysis of paroxetine during pharmacokinetic profiling of the drug.

Calibration↗
PubMed1999

Quantitative analysis of epidermal innervation in Fabry disease.

OBJECTIVE: To use skin biopsy specimens to quantitate the cutaneous innervation density of Fabry patients who had preserved renal function. BACKGROUND: The small fiber neuropathy of Fabry disease is difficult to detect and quantitate by conventional methods. Because this neuropathy is a common characteristic of Fabry disease, quantitating changes in this parameter would be helpful in demonstrating the effectiveness of enzyme or gene replacement therapy. METHODS: Patients underwent skin biopsy at the thigh and foot. Innervation density was determined by counting free nerve endings in the epidermis. These data were compared with nerve conduction studies, and in selected patients, fiber quantitation of sural nerve biopsy specimens. RESULTS: The Fabry patients had normal results of nerve conduction studies and large fiber quantitation by sural nerve biopsy. However, the involvement of small cutaneous fibers in these patients was easily demonstrable and quantifiable by skin biopsy. All patients showed severe loss of intraepidermal innervation at the ankle, but fiber loss at the distal thigh was proportionately less severe. CONCLUSIONS: The nerve damage in Fabry patients with preserved renal function involves exclusively small myelinated and unmyelinated fibers, and skin biopsy is a useful in detecting and quantitating such damage. Comparison of cutaneous innervation density with quantitation of sural nerve biopsy specimens demonstrated that skin biopsy specimens were as sensitive in detecting the presence of neuropathy as were the nerve specimens. It is speculated that analysis of cutaneous innervation may provide a useful marker of the nervous system's response to specific therapy for Fabry disease.

Adult↗
PubMed2005

Quantitative analysis of the "warm-up" phenomenon in myotonic dystrophy type 1.

To quantitate improvement in hand-grip myotonia and muscle strength (i.e., the "warm-up" phenomenon) in myotonic dystrophy type 1 (DM1), six successive, standardized maximum voluntary isometric contractions (MVICs) were recorded on 2 separate days using a computerized isometric hand-grip myometer in 25 genetically confirmed DM1 patients and in 17 normal controls. An automated computer program placed cursors along the declining (relaxation) phase of the MVICs at 90%, 50%, and 5% of peak force (PF) and calculated relaxation times (RTs) between these points. Mean 90% to 5% RT (a measure of myotonia) rapidly declined from 2.5 s in MVIC 1 to 0.8 s in MVIC 6 (warm-up = 1.7 s) in DM1; in controls, it remained 0.4 s for all six MVICs (warm-up = 0). In DM1, 70% of warm-up occurred between MVIC 1 and 2, almost exclusively in the terminal 50% to 5% phase of muscle relaxation. Day 1 warm-up was highly correlated with the severity of myotonia, and with day 2 warm-up. Improvement in myotonia was not accompanied by either transient paresis or improvement in PF. We conclude that, with this testing paradigm: warm-up of myotonia in DM1 can be reliably measured; is proportional to severity of myotonia; occurs rapidly, being most prominent between the first and second grips; mainly results from shortening of the terminal phase of muscle relaxation; and is not accompanied by significant warm-up in force output.

Adult↗
PubMed2005

Enhancing the ratio of molecular ions to non-covalent compounds in the electrospray interface of LC-MS in quantitative analysis.

A common problem encountered during the development of MS methods for the quantitation of small organic molecules by LC-MS is the formation of non-covalently bound species or adducts in the electrospray interface. Often the population of the molecular ion is insignificant compared to those of all other forms of the analyte produced in the electrospray, making it difficult to obtain the sensitivity required for accurate quantitation. We have investigated the effects of the following variables: orifice potential, nebulizer gas flow, temperature, solvent composition and the sample pH on the relative distributions of ions of the types MH+, MNa+, MNH4+, and 2MNa+, where M represents a small organic molecule: BAY 11-7082 ((E)-3-[4-methylphenylsulfonyl]-2-propenenitrile). Orifice potential, solvent composition and the sample pH had the greatest influence on the relative distributions of these ions, making these parameters the most useful for optimizing methods for the quantitation of small molecules.

Chromatography, High Pressure Liquid↗
PubMed1987

Quantitative analysis of synaptogenesis in the cerebral cortex of the cat suprasylvian gyrus.

A quantitative study was made of the synapses in the association cortex of the suprasylvian gyrus and in the adjacent subcortical region, in kittens from birth (P0) to 103 days (P103), and in two adults. The quantitative data were corrected using the neuropil and the growth coefficients. At P0, the synaptic density of the cortex is only 7% of the adult density. The synapses are disposed preferentially in layers I, III and V. The rush of the synaptic density apparently starts at P9, or at P12 after correction using the growth coefficient. At this time, the cortico-cortical connections begin to form. During the rush, the synaptic peaks of the newborn animal disappear; the synaptic density reaches its maximum at P28-P35, exceeding the adult density by 53 to 82%. After P35, there appears a real, although very slow, elimination of synapses. This elimination touches the superficial layers (I to III) first, and then the deep layers. The young neuron, seeking a qualitative and quantitative equilibrium of its afferents and its efferents, seems to be responsible for this elimination. The superficial cortex always contains more synapses (60%) than the subjacent cortex, regardless of the animal's age. The rush is greatest here, as is the elimination. The question of senescence arises: since the majority of the synapses are very probably of cortico-cortical origin in this cortex, this process would seem to be due to a loss of association connections. Indeed, one of the two adults analyzed revealed a loss of synapses in the superficial layers of its cortex, as well as in layer VI. The synapses are present in the subcortical region, without discontinuity with the cortex in all animals. In the youngest, synapses were observed down to 2 mm below the cerebral cortex: the neurons establish a few rare contacts before reaching their definitive site. In the adult, the white matter is totally devoid of synapses. Since the elimination of synapses appears to be a process which continues throughout life, the term "maturity" cannot be attributed solely on the basis of the histologic components, but must result from an evaluation of behavior.

Animals↗
PubMed2003

Two-center clinical evaluation of a new automated fluorometric immunoassay for the quantitative analysis of total betaeta-human chorionic gonadotropin.

OBJECTIVES: This study evaluated the quantitative total betahCG assay on the Stratus CS point-of-care instrument at two medical centers. DESIGN AND METHODS: Analytical sensitivity, linearity, within-run and total imprecision, interferences, dilution recovery, method comparison (Dimension RxL), comparison of matched heparinized whole blood and plasma samples, and determination of the normal reference interval were studied. RESULTS: Analytical sensitivity was <0.5 IU/L. The assay's linear range was 0 to 1250 IU/L; the clinical reportable range was up to 50,000 IU/L. Within-run imprecision (CV) at both low (<20 IU/L) and elevated (760 IU/L) betahCG concentrations were <4%. Total imprecision for three QC levels and two pools were <4%. Method comparison showed Stratus CS betahCG = 0.98 +/- 0.01* Dimension RxL hCG -0.11 +/- 2.69 (n = 136; r = 0.996; Sy/x = 27.7). Matched heparinized whole blood/plasma sample-comparison showed: whole blood = 1.05*Plasma + 0.37 +/- 1.29 (n = 41; r = 1.000; Sy/x = 7.57). Mean dilution recovery was 99% (range: 95% to 103%). None of the 52 drugs tested, lipemia, icterus, hemolysis, LH, FSH, TSH, hGH or prolactin represented a significant interference with the assay. Reference intervals were <0.5 IU/L for males (n = 123) and <3.0 IU/L for nonpregnant females (n = 120). CONCLUSIONS: The Stratus CS betahCG test offers the advantage of quantitative measurement of total betahCG in whole blood at the point of care and is suitable for clinical use.

Calibration↗
PubMed1989

Toward a quantitative analysis of corneal endothelial cell morphology: a review of techniques and their application.

Quantitative assessments of endothelial cell density, area, and shape have become increasingly common over the last 10 years. Despite the relatively widespread availability of instruments for in vivo (specular microscopy) or in vitro (scanning electron microscopy or histological techniques) assessment of the endothelial mosaic, little standardization of reporting of these characteristics has occurred. A comprehensive summary and review of the assessments of cell density in normal and pathological corneas, assessments of cell area (of its variance, coefficient of variation, polymegethism), and assessments of cell shape (pleomorphism, index of hexagonality, shape factors, figure coefficients, elongation index) is presented. An attempt is made to relate these numerous procedures and reporting methods by an objective critique both of the methods and of the many studies.

Cell Count↗
PubMed1999

Quantitative analysis of impedance spectra of organs during ischemia.

We have developed a rapid, quantitative procedure to fit the spectra of the real and imaginary part of tissue impedance, providing characteristic parameters: time constants, their distribution, and the amplitudes of associated dispersions. Based on the time course of tissue impedance during ischemia, we have derived the evolution of characteristic parameters for both myocardial and liver tissue. The similar evolution of the distribution of time constants for myocardial and liver tissue is emphasized and discussed.

Animals↗
PubMed1981

Quantitative analysis of purine and pyrimidine metabolism in Chinese hamster ovary cells.

A detailed quantitative study of purine and pyrimidine metabolism in logarithmically growing Chinese hamster ovary cells has been performed. Direct measurements of the ribonucleoside and deoxyribonucleoside triphosphate pool sizes have been made, and the pathways and rates of metabolism of adenine, hypoxanthine, guanine, guanosine, deoxyadenosine, and deoxyguanosine and of uridine, cytidine, deoxycytidine, deoxyuridine, and thymidine have been determined.

Animals↗
PubMed2004

A quantitative analysis of qualitative studies in clinical journals for the 2000 publishing year.

BACKGROUND: Quantitative studies are becoming more recognized as important to understanding health care with all of its richness and complexities. The purpose of this descriptive survey was to provide a quantitative evaluation of the qualitative studies published in 170 core clinical journals for 2000. METHODS: All identified studies that used qualitative methods were reviewed to ascertain which clinical journals publish qualitative studies and to extract research methods, content (persons and health care issues studied), and whether mixed methods (quantitative and qualitative methods) were used. RESULTS: 60 330 articles were reviewed. 355 reports of original qualitative studies and 12 systematic review articles were identified in 48 journals. Most of the journals were in the discipline of nursing. Only 4 of the most highly cited health care journals, based on ISI Science Citation Index (SCI) Impact Factors, published qualitative studies. 37 of the 355 original reports used both qualitative and quantitative (mixed) methods. Patients and non-health care settings were the most common groups of people studied. Diseases and conditions were cancer, mental health, pregnancy and childbirth, and cerebrovascular disease with many other diseases and conditions represented. Phenomenology and grounded theory were commonly used; substantial ethnography was also present. No substantial differences were noted for content or methods when articles published in all disciplines were compared with articles published in nursing titles or when studies with mixed methods were compared with studies that included only qualitative methods. CONCLUSIONS: The clinical literature includes many qualitative studies although they are often published in nursing journals or journals with low SCI Impact Factor journals. Many qualitative studies incorporate both qualitative and quantitative methods.

Bibliometrics↗
PubMed1989

Quantitative analysis of collagen expression in embryonic chick chondrocytes having different developmental fates.

A quantitative determination of collagen expression was carried out in cultured chondrocytes obtained from a tissue that undergoes endochondral bone replacement (ventral vertebra) and one that does not (caudal sterna). The "short chain" collagen, type X is only expressed in the former while the other "short chain" collagen type IX, was primarily expressed in the latter. These two tissues also differ in that vertebral chondrocytes express moderate levels of both type I procollagen mRNAs which were translated into full length procollagen chains both in vivo and in vitro, while caudal sternal chondrocytes did not. The percent of collagen synthesis was about 50% in both cell types, but sternal cells expressed twice as much collagen as vertebral cells even though type II procollagen was more efficiently processed to alpha-chains in vertebral chondrocytes than in sternal chondrocytes. The number of type II procollagen mRNA molecules/cell was found to be about 2300 in vertebral chondrocytes and about 8000 in sternal cells, in good agreement with the results reported by Kravis and Upholt (Kravis, D., and Upholt, W. B. (1985) Dev. Biol. 108, 164-172). There were about 630 copies of type I procollagen mRNAs with an alpha 1/alpha 2 ratio of 1.6 in vertebral chondrocytes compared with 5100 copies and an alpha 1/alpha 2 ratio of 2.2 in osteoblasts, and less than 40 copies in sternal cells. Since the rate of type I collagen chain synthesis was 50 times greater in osteoblasts than in vertebral cells, type I procollagen mRNAs were about six times less efficiently translated in vertebral cells than in osteoblasts. The type I mRNAs in vertebral chondrocytes were polyadenylated and had 5' ends that were identical in osteoblasts, fibroblasts, and myoblasts. Moreover, type I mRNAs isolated from vertebral chondrocytes were translated into full length preprocollagen chains in vitro in rabbit reticulocyte lysates. Thus, chondrocytes isolated from cartilage tissues with different developmental fates differed quantitatively and qualitatively in total collagen synthesis, procollagen processing, and distribution of collagen types.

Animals↗
PubMed1996

Rapid and quantitative analysis of bilirubin in equines by high-performance liquid chromatography.

Rapid and quantitative analytical methods for bilirubin using high-performance liquid chromatography (HPLC) with UV detection were developed for samples from equines at a meat inspection site. Sharp HPLC peaks for bilirubins, unconjugated bilirubin (UCBL) and conjugated bilirubin (CBL), were obtained using a simple mobile phase of methanol:0.5 M Tris-HCl buffer (65:35, v/v, pH 7.4). A variable wavelength detector set at 450 nm, 0.01 AUFS and a recorder set at 4 cm/min were used for detection. Peaks for UCBL and CBL occurred at 7.1 min and 4.9 min, the lower limits of detection ranged between 0.16 and 0.78 microgram/ml, respectively. Orange II, for which the retention time was 3.6 min, was selected as an internal standard. When the samples were analysed from healthy equines and those suspected of being jaundiced due to a yellow colour change in the carcasses, only UCBL peaks were recognized, and CBL peaks were never obtained. Aqueous humour is a very common sample at meat inspections but UCBL or CBL peaks were all absent in both healthy and clinical samples from equines. There were reliable correlations between UCBL peaks (microV) using HPLC and total bilirubin value (mg/dl) measured by the total bilirubin assay kit in serum. A correlation between peak height (microV) on HPLC from serum samples and that of pericardial fluid samples was obtained.

Animals↗
PubMed1985

Quantitative analysis of liver function in percutaneous transhepatic biliary drainage patients.

The diagnostic usefulness of Tc-99m DISIDA cholescintigraphy as a predictor of eventual catheter and hepatic function in patients who have undergone percutaneous transhepatic biliary drainage (PTBD) for extrahepatic biliary obstruction was evaluated. Twenty-nine cholescintigrams were performed in 14 patients. The examinations were divided into two groups: Group A (N = 17), in which the patient's clinical status deteriorated within two to three days post-PTBD, and Group B (N = 12), in which the patients did well clinically post-PTBD. No significant difference between the two groups was demonstrated by visual analysis of the analog images or by analysis of serum bilirubin levels. A computer program, developed by the authors, quantitates several parameters of DISIDA kinetics, reflecting hepatic function based upon compartmental analysis. A significant difference (P less than .001) was demonstrated between the mean transport constants (blood clearance constant = k1; hepatic clearance constant = k2) for the two groups. It is concluded that serum bilirubin levels and visual inspection of analog images are inadequate independent predictors of hepatic function in patients post PTBD. The transport constants k1 and k2 are quantitative parameters of hepatic function that may be of prognostic value in patients post PTBD.

Adult↗
PubMed1998

Quantitative analysis of yeast gene function using competition experiments in continuous culture.

One possible route to the evaluation of gene function is a quantitative approach based on the concepts of metabolic control analysis (MCA). An important first step in such an analysis is to determine the effect of deleting individual genes on the growth rate (or fitness) of S. cerevisiae. Since the specific growth-rate effects of most genes are likely to be small, we employed competition experiments in chemostat culture to measure the proportion of deletion mutants relative to that of a standard strain by using a quantitative PCR method. In this paper, we show that both densitometry and GeneScan analysis can be used with similar accuracy and reproducibility to determine the proportions of (at least) two strains simultaneously, in the range 10-90% of the total cell population. Furthermore, we report on a model competition experiment between two diploid nuclear petite mutants, homozygous for deletions in the cox5a or pet191 genes, and the standard strain (ho::kanMX4/ho::kanMX4) in chemostat cultures under six different physiological conditions. The results indicate that competition experiments is continuous culture are a suitable method to distinguish quantitatively between deletion mutants that qualitatively exhibit the same phenotype.

Culture Media↗
PubMed1995

Quantitative analysis of the plain radiographic appearance of aneurysmal bone cysts.

RATIONAL AND OBJECTIVES: To quantitate radiographic features that distinguish the plain radiographic appearance of aneurysmal bone cyst (ABC) from other solitary lesions of bone. MATERIALS AND METHODS: Seven hundred nine cases of focal bone lesions, including 32 ABCs 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 ABC in contrast with other lesions in the data base. RESULTS: Aneurysmal bone cysts most consistently are medullary-based, either eccentric or centric (94%), show lysis (100%), cortical thinning (97%), enlargement of the host bone (100%), and geographic bone destruction (94%). They have well-defined edges (84%), no fallen fragment (100%), no evidence of periosteal reaction (75%), and no visible matrix (91%). Although they typically occur in the metadiaphysis of long bones, the anatomic location and demographic data did not significantly affect the sensitivity or specificity for detection of ABCs. The vector analysis-generated differential diagnoses include giant cell tumor, unicameral bone cyst, nonossifying fibroma, enchondroma, and fibrous dysplasia as the major lesions.

Adolescent↗
PubMed1991

Quantitative analysis of inflammatory cell influx, procollagen type I synthesis, and collagen cross-linking in incisional wounds: influence of PDGF-BB and TGF-beta 1 therapy.

Platelet-derived growth factor (PDGF-BB homodimer) and transforming growth factor-beta 1 (TGF-beta 1) are potent wound-healing hormones that accelerate incisional repair. To identify more precisely and quantitatively the stage(s) of wound healing influenced by growth-factor therapy, we investigated the three sequential tissue repair processes--inflammatory cell influx, intracellular procollagen type I (PC-I) synthesis, and collagen cross-linking--in recombinant growth factor--treated wounds. Using newly developed automated, quantitative image-analysis techniques, we observed that PDGF-BB markedly augmented the directed migration of macrophages into wounds during the first week after wounding and triggered and earlier and more sustained influx of PC-I--containing fibroblasts into the wound when compared with results in TGF-beta 1-treated or control wounds (p = 0.015 at day 2; p = 0.007 at day 21). In contrast, automated image analysis revealed TGF-beta 1-treated wound fibroblasts had a nearly twofold increase in intracellular levels of PC-I protein when compared with PDGF-BB-treated or control wound fibroblasts (p = 0.004 at day 4). However, the influence of TGF-beta 1 was transient, and the longer duration of PDGF-BB activity suggested a later influence, perhaps on the collagen remodeling phase, which is ultimately required for increased wound strength. To address this possibility, collagen cross-linking in growth factor-treated wounds was inhibited by beta-aminoproprionitrile (BAPN) treatment, and wound breaking strength was analyzed. Both PDGF-BB and TGF-beta 1 continued to enhance repair in BAPN-treated rats, indicating that they do not function primarily at the level of collagen cross-linking. Thus, PDGF-BB appears to enhance the inflammatory phase of wound healing to indirectly trigger PC-I synthesis, whereas TGF-beta 1 quantitatively enhances PC-I synthesis directly, accounting for their differing duration of activities within healing wounds.

Aminopropionitrile↗
PubMedDate not supplied

Determination of melengestrol acetate in feedstuffs with liquid chromatographic preparatory column cleanup and quantitative analysis.

Melengestrol acetate (MGA) is determined by liquid chromatography using a fraction from preparatory LC as a means of sample cleanup for feedstuffs, both dry and liquid. Dry ground feed is Soxhlet extracted with hexane and passed through a 2% deactivated alumina column for initial cleanup. The eluate is evaporated, redissolved in methanol, filtered, and injected onto a preparatory LC column. The fraction containing MGA is separated from the remaining matrix, evaporated to dryness, dissolved in methanol, and quantitated by LC analysis. Liquid supplements are extracted in methanol, and the extract is evaporated to near dryness. The residue is diluted with water, extracted with chloroform, passed through sodium sulfate, and evaporated to dryness. The remaining sample is dissolved in methanol prior to preparative LC and quantitative LC. Recoveries for 2 laboratory-fortified commercial feeds, one dry and one liquid, containing 0.39 and 0.40 mg/lb, were 98.3% +/- 4.4 and 95.8% +/- 4.3, respectively. Results compare favorably with existing methods. Up to a 4-fold time savings was realized by this method without automation.

Animal Feed↗
PubMed1980

Cerebellar dyssynergia in humans--a quantitative analysis.

Patients with cerebellar lesions and limb ataxia performed two types of continuous tracking tasks involving flexion and extension of the index finger. In both tasks, patients were provided cutaneous and proprioceptive cues, but visual feedback was given in the first task (visual tracking) and not in the second (arbitrarily termed proprioceptive tracking). Raw records and Fourier-analyzed power spectra were compared with results in normal controls. Harmonic distortion was determined for each task. In all patients, as well as normal subjects, tracking performance was markedly improved and harmonic distortion substantially reduced during proprioceptive tracking. This surprising finding may result from a much shorter feedback loop for proprioceptive stimuli compared to visual stimuli. The tracking records, power spectra analysis, and determination of harmonic distortion provide both qualitative and quantitative data in patients with dyssynergia.

Cerebellar Ataxia↗