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PubMedDate not supplied

Gender differences in dimensions of anxiety sensitivity.

Anxiety sensitivity (AS) is the fear of anxiety-related sensations arising from beliefs that these sensations have harmful physical, psychological, or social consequences. AS is measured using the Anxiety Sensitivity Index (ASI), a 16-item self-report questionnaire. Little is known about the origins of AS, although social learning experiences (including sex-role socialization experiences) may be important. The present study examined whether there were gender differences in: (a) the lower- or higher-order factor structure of the ASI; and/or (b) pattern of ASI factor scores. The ASI was completed by 818 university students (290 males; 528 females). Separate principal components analyses on the ASI items of the total sample, males, and females revealed nearly identical lower-order three-factor structures for all groups, with factors pertaining to fears about the anticipated (a) physical, (b) psychological, and (c) social consequences of anxiety. Separate principal components analyses on the lower-order factor scores of the three samples revealed similar unidimensional higher-order solutions for all groups. Gender x AS dimension analyses on ASI lower-order factor scores showed that: females scored higher than males only on the physical concerns factor; females scored higher on the physical concerns factor relative to their scores on the social and psychological concerns factors; and males scored higher on the social and psychological concerns factors relative to their scores on the physical concerns factor. Finally, females scored higher than males on the higher-order factor representing the global AS construct. The present study provides further support for the empirical distinction of the three lower-order dimensions of AS, and additional evidence for the theoretical hierarchical structure of the ASI. Results also suggest that males and females differ on these various AS dimensions in ways consistent with sex role socialization practices.

Adolescent↗

PubMed2000

Nonparametric regression applied to quantitative structure-activity relationships

Several nonparametric regressors have been applied to modeling quantitative structure-activity relationship (QSAR) data. The simplest regressor, the Nadaraya-Watson, was assessed in a genuine multivariate setting. Other regressors, the local linear and the shifted Nadaraya-Watson, were implemented within additive models--a computationally more expedient approach, better suited for low-density designs. Performances were benchmarked against the nonlinear method of smoothing splines. A linear reference point was provided by multilinear regression (MLR). Variable selection was explored using systematic combinations of different variables and combinations of principal components. For the data set examined, 47 inhibitors of dopamine beta-hydroxylase, the additive nonparametric regressors have greater predictive accuracy (as measured by the mean absolute error of the predictions or the Pearson correlation in cross-validation trails) than MLR. The use of principal components did not improve the performance of the nonparametric regressors over use of the original descriptors, since the original descriptors are not strongly correlated. It remains to be seen if the nonparametric regressors can be successfully coupled with better variable selection and dimensionality reduction in the context of high-dimensional QSARs.

Journal Article↗

PubMed1993

[Grouping of countries according to indicators of standard of living].

The position of 125 countries is studied on the basis of a collection of 26 basic, health, economic and educational indicators. Multivariate statistical methods were used, including Cluster Analysis, Principal Component Analysis and Multivariate Analysis of Variance. The most discriminating variables were life expectancy the child mortality rate, the mortality rate of children of less than five years of age, the birth and fertility rates and the high-school female matriculation rate. The first principal component was interpreted as a measure of the living standard which made it possible to place the countries in order. Five clusters of countries are suggested.

Global Health↗

PubMed2006

Tillage and field scale controls on greenhouse gas emissions.

There is a lack of understanding of how associations among soil properties and management-induced changes control the variability of greenhouse gas (GHG) emissions from soil. We performed a laboratory investigation to quantify relationships between GHG emissions and soil indicators in an irrigated agricultural field under standard tillage (ST) and a field recently converted (2 yr) to no-tillage (NT). Soil cores (15-cm depth) were incubated at 25 degrees C at field moisture content and 75% water holding capacity. Principal component analysis (PCA) identified that most of the variation of the measured soil properties was related to differences in soil C and N and soil water conditions under ST, but soil texture and bulk density under NT. This trend became more apparent after irrigation. However, principal component regression (PCR) suggested that soil physical properties or total C and N were less important in controlling GHG emissions across tillage systems. The CO2 flux was more strongly determined by microbial biomass under ST and inorganic N content under NT than soil physical properties. Similarly, N2O and CH4 fluxes were predominantly controlled by NO3- content and labile C and N availability in both ST and NT soils at field moisture content, and NH4+ content after irrigation. Our study indicates that the field-scale variability of GHG emissions is controlled primarily by biochemical parameters rather than physical parameters. Differences in the availability and type of C and N sources for microbial activity as affected by tillage and irrigation develop different levels and combinations of field-scale controls on GHG emissions.

Biomass↗

PubMed1991

[Influence of mother's heterozygosity on the variation of anthropometric traits in newborns].

The relationship between mother's heterozygosity as revealed by 14 polymorphic loci and variation of the set of anthropometric traits were studied in normal singleton newborns (174 boys, 127 girls). Statistically significant negative correlation between mother's heterozygosity and the index of fluctuating asymmetry was found in girls. Variances of four traits--body weight, body length, circumference of head and breast measured by first principal component, and mean number of minor deviations from development (stigma) are shown to be minimal in the children born by mothers with the average level of heterozygosity. The groups of newborns with different level of mother's heterozygosity are characterized by different combinations of first principal component, stigma, and the index of fluctuating asymmetry. It is concluded from the whole set of data that children born by mothers with the average level of heterozygosity have the highest level of viability.

Anthropometry↗

PubMed1994

Evidence for multiple genes determining sodium transport.

Sodium transport comprises a set of interacting systems. Consequently, a defective sodium transport gene affects multiple sodium transport systems, and a sodium transport variable measured on a sample of individuals reflects genetic variation from a number of different genes, complicating the task of identifying the effect of a single gene. To test for genes which affect sodium transport, we first applied principal components analysis to 14 variables related to sodium transport, thereby defining uncorrelated sources of variation in the variables. The sample consisted of 1,218 members of 68 pedigrees ascertained through probands with early-onset stroke, hypertension, or coronary heart disease. Segregation analysis of the 14 principal components scores provided evidence for 8 genetic variants which alter sodium transport. One of the 8 variants is recessive, has homozygous genotype frequency estimated as 8.8% of the population, and increases sodium-lithium countertransport, the passive sodium leak, body mass index, and triglyceride; the genetic variant may coincide with an insulin resistance gene. A second of the 8 variants is also recessive, has homozygous genotype frequency estimated as 7.4% of the population, and increases intraerythrocytic sodium and the passive sodium leak while decreasing sodium pump number; the genetic variant may reduce pump number. Two of the 8 variants substantially increase sodium-lithium countertransport; frequency estimates for heterozygotes for the dominant variant and homozygotes for the recessive variant equal 1.8% and 3.1%, respectively. Another of the 8 variants is recessive, has homozygous genotype frequency estimated as 1.9%, and increases body mass index. Each of the 3 remaining variants is rare and expressed in less than 1% of the sample.

Cardiovascular Diseases↗

PubMedDate not supplied

The reliability and validity of the junior temperament and character inventory.

The purpose of this study was to evaluate the reliability and validity of the Junior Temperament and Character Inventory (Junior TCI), a child and adolescent version of the Adult Temperament and Character Inventory (TCI), which is based on Cloninger's biosocial model of personality. The Junior TCI was translated into Korean and administered to 663 Korean middle school students (male/female, 360/303; age, 13.3 +/- 1.0 years) and their parents (mother/father, 444/84). Internal consistency was calculated by Cronbach alpha. A test-retest study of the Junior TCI was conducted across a 3-month interval with 97 subjects. Factor analyses for the temperament and character dimensions were performed using principal component analysis, rotating factors by Promax. Cronbach alpha values of the Junior TCI scales ranged from.48 to.80 for the temperament scales and from.64 to.68 for the character scales. Test-retest correlations ranged from.62 to.85 for the temperament scales and from.76 to.79 for the character scales. Principal component factor analyses showed three factors out of four temperament scales (Harm Avoidance 1 to 4; Novelty Seeking 1 to 4; Persistence; and Reward Dependence 1, 3, 4) and three factors out of three character scales (Self-Directedness 1 to 5; Cooperativeness 1 to 5; and Self-Transcendence 1 to 3) that were similar to factor structures of adult versions of the TCI. Explorative factor analysis with a condition of eigenvalue greater than 1 produced six factors, as compared to seven factors extracted in Cloninger's original report of the adult TCI. In conclusion, this was the first study to tests and report detailed psychometric properties of the Junior TCI. The current study confirms that the Junior TCI has satisfactory psychometric properties for the use in child and adolescent populations and reflects Cloninger's biosocial model of personality.

Adolescent↗

PubMed2005

Liquid chromatography-mass spectrometric analysis of urinary metabolites and their pattern recognition for the prediction of drug-induced hepatotoxicity.

Multivariate pattern recognition (PR) analysis combined with LC/MS was utilized to evaluate the feasibility of predicting chemical-induced toxicity in rats. Urine samples were collected from rats treated with vehicles or four hepatotoxins, alpha-naphthyl isothiocyanate (ANIT), carbontetrachloride (CCl4), acetaminophen, and diclofenac, and analyzed by HPLC coupled with electrospray mass spectrometry. Chromatographic data were normalized using modified Z score transformation with those of the control group, to remove the vehicle effects for a further enhanced multivariate analysis. The LC/MS-based profiles of the urine samples showed different levels of endogenous metabolites, which were characteristic of each hepatotoxin. In the principal component (PC) map of the urinary spectra from rats treated with ANIT, the metabolic trajectory moved away from the predose position, reaching a maximum separation at the 32-48 h time period. The metabolic profiles partially recovered to the basal conditions on 7 days postdose. A principal component analysis was performed on the urinary spectra of rats treated with the vehicles or four hepatotoxins. Each group formed a distinct and isolated cluster in the PC map, indicating drug-induced perturbation in the urine profiles. To construct mathematical models for predicting drug-induced hepatotoxicity, supervised analyses, such as linear discriminant analysis and soft independent modeling of class analogy with residual distance (SIMCA-RD), were performed. The SIMCA-RD showed high predictability, over 95%, in the results of cross-validation using the leaving-one-out method. The developed LC/MS-PR approach might be a useful tool for the prediction of drug-induced hepatotoxicity and for the understanding of hepatotoxic mechanisms.

1-Naphthylisothiocyanate↗

PubMed1989

Development and validation of an instrument to measure patient satisfaction with pharmacy services.

A research program was undertaken to develop and validate a multidimensional measure of patient satisfaction with pharmacy services. A self-administered questionnaire consisting of 44 Likert-type attitudinal items was adapted from the Patient Satisfaction Questionnaire developed by Ware et al. In an iterative scale development process, the adapted questionnaire and its revisions were evaluated in three successive studies conducted on convenience samples (n = 30, 313, 489) of individuals in attendance at family practice clinics in a southwestern city. Methods used to construct multi-item scales measuring separate dimensions of service included principal components factor analysis and item analyses. Acquiescent response set (ARS), the tendency to agree with statements of opinion regardless of content, was measured by the method of matched pairs of items. A partial correlation matrix which controlled for ARS was used as the data in a principal components factor analysis in an effort to reduce the biasing effect of ARS on factor analytic outcomes. Dimensions of satisfaction identified were Explanation, Consideration, Technical Competence, Financial Aspects, Accessibility, Drug Efficacy, OTC (over-the-counter) Product Availability, and Quality of the Drug Product. Questionnaire revision is suggested to confirm the validity of the latter two dimensions Future research should examine the relationship between separate dimensions of satisfaction and other patient attitudes and behaviors, and the convergence between this instrument and other measures of patient satisfaction with pharmacy services.

Adolescent↗

PubMed2006

Analysis of DGGE profiles to explore the relationship between prokaryotic community composition and biogeochemical processes in deep subseafloor sediments from the Peru Margin.

The aim of this work was to relate depth profiles of prokaryotic community composition with geochemical processes in the deep subseafloor biosphere at two shallow-water sites on the Peru Margin in the Pacific Ocean (ODP Leg 201, sites 1228 and 1229). Principal component analysis of denaturing gradient gel electrophoresis banding patterns of deep-sediment Bacteria, Archaea, Euryarchaeota and the novel candidate division JS1, followed by multiple regression, showed strong relationships with prokaryotic activity and geochemistry (R(2)=55-100%). Further correlation analysis, at one site, between the principal components from the community composition profiles for Bacteria and 12 other variables quantitatively confirmed their relationship with activity and geochemistry, which had previously only been implied. Comparison with previously published cell counts enumerated by fluorescent in situ hybridization with rRNA-targeted probes confirmed that these denaturing gradient gel electrophoresis profiles described an active prokaryotic community.

Archaea↗

PubMed1985

Antibiotypes of Bacteroides gingivalis assessed by antimicrobial disks and multivariate analysis.

Antibiograms with 20 different antimicrobial disks were studied for antibiotyping of Bacteroides gingivalis isolates. The stability of the antibiotypes was tested by passage in mice. Several B. gingivalis isolates of the same subject were used to investigate the presence of different antibiotypes in one individual, while isolates from different subjects were used to investigate individual differences. The antibiotypes were found to remain stable after animal passage. All tested strains of different origin represented different antibiotypes. The isolates from one subject all belonged to the same antibiotype. Principal component analysis of the data showed that two factors were important in the discrimination of the strains of B. gingivalis. One included beta-lactam antimicrobial agents that affect the cell wall. The other included antimicrobial agents that inhibit synthesis of protein and nucleic acid. Both principal component analysis and discriminant analysis proved to be of great use in the reduction of the amount of data and the visualization of the relations between different antibiotypes of B. gingivalis in a linear map. Among the investigated subjects, different antibiotypes of B. gingivalis were found, indicating that in the mouth of an individual, one antibiotype of B. gingivalis predominates and that different persons harbor different antibiotypes of B. gingivalis.

Analysis of Variance↗

PubMed2005

[The population gene pool of Yakutia: cartographic analysis based on the polymorphism of immune and biochemical markers].

The gene pool of the indigenous population of Sakha Republic (Yakutia) has been studied within the borders of this republic coinciding with the main area of Yakuts, which was formed by the end of the 19th century and have remained stable until the present time. Maps of the geographic variation of the integrated characteristics of the Yakut gene pool, including the principal components, parameters of genetic diversity, and genetic distances from the "average" Yakut population are presented. It has been demonstrated that ethnographers' reports on intense internal assimilation in modem Yakutia agree with genetic data. The stratification of the Yakut gene pool reflected in the maps of two principal components corresponds to the observed general (H(T)) and interpopulation (FST) gene diversities.

Biomarkers↗

PubMed1995

Laminar organization of receptive field properties in the dorsal lateral geniculate nucleus of the tree shrew (Tupaiaglis belangeri).

A laminar analysis of the receptive field properties of relay cells in the binocular region of the tree shrew dorsal lateral geniculate nucleus (LGN) found three main subdivisions. Lamina 1 (receiving ipsilateral eye input) and lamina 2 (contralateral) comprise a pair of layers that contain only ON-center neurons. Laminae 4 (contralateral) and 5 (ipsilateral) comprise a pair of layers with mostly OFF-center cells (86%). Laminae 3 and 6 (both contralaterally innervated) also form a distinct pair, although lamina 3 contains a mixture of cells with ON-centers (43%) or OFF-centers (57%), and lamina 6 contains mostly cells with ON-OFF centers and suppressive surrounds (81%). Cells located in the interlaminar zones resembled neurons in laminae 3 and 6. In comparison with the cells in the OFF-center laminae 4 and 5, the ON-center cells in laminae 1 and 2 had smaller, more elliptical receptive field centers with stronger responses to flashed visual stimuli. In addition, cells in the ipsilateral eye laminae 1 and 5 showed a greater change in center diameter, with eccentricity from the area centralis, than cells in the contralateral eye laminae 2 and 4. Principal components analysis using six receptive field properties (latency to optic chiasm stimulation, receptive field center diameter, maintained discharge rate, response onset latency, peak spike density, and phasic-tonic index) suggested that the cells in laminae 3 and 6 and the interlaminar zones are W-like. Principal components analysis of the same receptive field properties in laminae 1, 2, 4, and 5 did not reveal differences clearly related to X-like (parvocellular) and Y-like (magnocellular) categories. Ninety-seven percent of the cells tested for linearity of spatial summation in laminae 1, 2, 4, and 5 were linear. We conclude that the dominant organizational features of the tree shrew LGN are the ON-center, OFF-center, and W pairs of layers that project to different regions within the striate cortex.

Animals↗

PubMed1996

Muscle biopsy index for discriminating between endurance horses with different performance records.

Biopsies were taken from three different depths of the gluteus medius muscle of 36 endurance horses aged between four and 17 years. Twenty of the horses were considered excellent performers according to their three fastest records in endurance events over the previous two or three years. The other 16 horses were moderate performers, with a mean racing speed < 3.5 ms-1 (in 120 to 180 km endurance rides), < 4.0 ms-1 (in 80 to 120 km endurance rides) or < 3.75 ms-1 (in 40 to 60 km endurance rides). The biopsy specimens were analysed for fibre type distribution (type I, IIA and IIB), fibre area and relative fibre area. The activities of the enzymes citrate synthase, 3-hydroxy-acyl-CoA-dehydrogenase and lactate dehydrogenase were also determined. The data were subjected to discriminant analysis and principal component analysis. It was possible to discriminate correctly between the horses according to their performance records by means of the discriminant analyses when the histochemical and morphometric data from all three muscle biopsies were used, but not when data from only a single muscle biopsy were used. Principal component analysis confirmed that the most efficient muscle parameters describing the athletic potential of endurance horses were the percentages and relative areas of the fibre types. Horses with a better endurance performance had higher percentages and relative areas of types I and IIA fibres and lower percentages and relative areas of type IIB fibres than moderate performers.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed2005

Structured assessment of current mental state in clinical practice: an international study of the reliability and validity of the Current Psychiatric State interview, CPS-50.

OBJECTIVE: To develop a reliable standardized assessment of psychiatric symptoms for use in clinical practice. METHOD: A 50-item interview, the Current Psychiatric State 50 (CPS-50), was used to assess 237 patients with a range of psychiatric diagnoses. Ratings were made by interviewers after a 2-day training. Comparisons of inter-rater reliability on each item and on eight clinical subscales were made across four international centres and between psychiatrists and non-psychiatrists. A principal components analysis was used to validate these clinical scales. RESULTS: Acceptable inter-rater reliability (intra-class coefficient > 0.80) was found for 46 of the 50 items, and for all eight subscales. There was no difference between centres or between psychiatrists and non-psychiatrists. The principal components analysis factors were similar to the clinical scales. CONCLUSION: The CPS-50 is a reliable standardized assessment of current mental status that can be used in clinical practice by all mental health professionals after brief training.

Cross-Cultural Comparison↗

PubMed2004

Assessing repeatability and validity of a visual analogue scale questionnaire for use in assessing pain and lameness in dogs.

OBJECTIVE: To develop a visual analogue scale (VAS) questionnaire that is repeatable and valid for use in assessing pain and lameness in dogs. SAMPLE POPULATION: 48 client-owned dogs with mild to moderate lameness. PROCEDURE: The dogs were from 3 studies conducted during a 3-year period. Of the 48 dogs, 19 were used in repeatability assessment, 48 were used in principal component analysis, and 44 were used in model selection procedures and validity testing. A test-retest measure of repeatability was conducted on dogs with a change of < 10% in vertical peak force. A force platform was used as the criterion-referenced standard for detecting lameness. Principal component analysis was used to describe dimensionality of the data. Repeatable questions were used as explanatory variables in multiple regression models to predict force plate measurements. Peak vertical, craniocaudal, and associated impulses were the forces used to quantify lameness. The regression models were used to test the criterion validity of the questionnaire. RESULTS: 19 of 39 questions were found to be repeatable on the basis of a Spearman rank-correlation cut point of > 0.6. Model selection procedures resulted in 3 overlapping subsets of questions that were considered valid representations of the forces measured (vertical peak, vertical impulse, and propulsion peak). Each reduced model fit the data as well as the full model. CONCLUSIONS AND CLINICAL RELEVANCE: The VAS questionnaire was repeatable and valid for use in assessing the degree of mild to moderate lameness in dogs.

Animals↗

PubMedDate not supplied

Development of a model for classification of toxin-induced lesions using 1H NMR spectroscopy of urine combined with pattern recognition.

Pattern recognition approaches were developed and applied to the classification of 600 MHz 1H NMR spectra of urine from rats dosed with compounds that induced organ-specific damage in either the liver or kidney. Male rats were separated into groups (n = 5) and each treated with one of the following compounds; adriamycin, allyl alcohol, 2-bromoethanamine hydrobromide, hexachlorobutadiene, hydrazine, lead acetate, mercury II chloride, puromycin aminonucleoside, sodium chromate, thioacetamide, 1,1,2-trichloro-3,3,3-trifluoro-1-propene or dose vehicle. Urine samples were collected over a 7 day time-course and analysed using 600 MHz 1H NMR spectroscopy. Each NMR spectrum was data-reduced to provide 256 intensity-related descriptors of the spectra. Data corresponding to the periods 8-24 h, 24-32 h and 32-56 h post-dose were first analysed using principal components analysis (PCA). In addition, samples obtained 120-144 h following the administration of adriamycin and puromycin were included in the analysis in order to compensate for the late onset of glomerular toxicity. Having established that toxin-related clustering behaviour could be detected in the first three principal components (PCs), three-quarters of the data were used to construct a soft independent modelling of class analogy (SIMCA) model. The remainder of the data were used as a test set of the model. Only three out of 61 samples in the test set were misclassified. Finally as a further test of the model, data from the 1H NMR spectra of urine from rats that had been treated with uranyl nitrate were used. Successful prediction of the toxicity type of the compound was achieved based on NMR urinalysis data confirming the robust nature of the derived model.

Animals↗

PubMed1994

The development of a short generic version of the Sickness Impact Profile.

This study concerns the development of a short version of a well-known and much used clinimetric instrument called the Sickness Impact Profile (SIP). The SIP is a generic measure of functional status. Based on findings of a principal components analysis of over 800 SIPs from a multi-diagnostic population, a selection of 68 items divided over 6 dimensions was made and initially tested. As no support was found for the statistical validity of the categorical structure of the original SIP, a new structure, discovered through principal components analysis, was used as the basis for selecting items. Comparison of the scores on the selection with information provided by the original SIP showed very promising results: the 68 item selection may serve as a valid short SIP-version.

Female↗