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At least 1,603 records · Page 89Linked to original sources
PubMed2005

Analysis of Psoralea corylifolia L. fruits in different regions.

Application of multivariate data analysis has become a popular method in the last decades, mainly because it can provide information not otherwise accessible. The information includes classification, searching similarities, finding relationships, finding physical significance to principal components, etc. Twenty-two Chinese medicinal herbs containing twelve constituents were collected and determined by HPLC. The results were studied by hierarchical cluster analysis (HCA) and principal components analysis (PCA). It was shown that the samples could be clustered reasonably into three groups, hence corresponding with the typical habitats of Psoralea corylifolia L.

Chromatography, High Pressure Liquid↗
PubMed2007

Assessment of water quality and identification of pollution sources of plateau lakes in Yunnan (China).

The plateau lakes of Yunnan are important both ecologically and economically in China. Nevertheless, the human impact on water quality in these lakes has become increasingly highlighted. The water quality of 10 plateau lakes was monitored regularly over the period of 2000 through 2004 for 24 parameters. Multivariate statistical techniques, including cluster analysis (CA), factor analysis (FA), and principal component analysis (PCA), were employed to better interpret information about the water quality and its pollution sources. No obvious data reduction from CA/FA was found because three principal components (PCs) needed 14 variables to explain 85.01% of the total variance. However, three latent factors accounted for pollution mainly from the following sources: agricultural activities, residential activities and anthropogenic-toxic pollution from industrial effluents, or other special activities. Box-whiskers plots were employed to visually interpret the spatiotemporal variations of water quality variables, which were highly correlated with three PCs. Three types of water quality (i.e., low-, medium-, and high-polluted lakes) were determined through CA based on the similarity of water quality variables. Our results may provide helpful information for the authorities to effectively manage the water quality and make sound policies.

China↗
PubMed2006

The effects of type 1 diabetes and its long-term complications on physical and mental health status.

OBJECTIVE: To analyse how type 1 diabetes mellitus (DM) and the symptoms of its chronic long-term complications correlate with health status domains in the adult population in Finland. METHODS: A representative sample of patients with type 1 DM was selected randomly from the Finnish drug reimbursement registry. Participants reported symptoms, diagnoses and treatments indicating the presence and time of appearance of long-term complications, and completed the RAND 36 questionnaire. A principal component analysis was performed to compress the eight RAND 36 dimensions into composite domains of health status. The results were validated with split-sample analysis. Regression analyses were used to estimate the effects of age, sex, symptoms of long-term complications and comorbidities on the component T-scores. RESULTS: Of the 752 (70.8%) responders, 592 fulfilled the criteria of type 1 DM. Of these, 82.6% fully completed the RAND 36 questionnaire. Principal component analysis of our data supports the theory of the 2-factor model of health, as physical and mental health domains were reflected unambiguously by different RAND 36 dimensions. The regression results show that the symptoms of long-term complications correlate more strongly with the physical than the mental domain of health status. CONCLUSION: Type 1 DM, and especially the symptoms of its long-term complications, correlate mainly with the physical domain of health, although the mental domain is also affected. The prevalence of long-term complications with type 1 DM is sufficiently high within the Finnish population to substantially influence the health status of people with type 1 DM.

Adult↗
PubMed2001

Statistical pattern analysis of gene expression profiles for glioblastoma tissues and cell lines.

The recent development and refinement of cDNA array and genechip techniques allows for large-scale parallel screening of gene expression and thereby provides a global assessment of molecular events transpiring in cell populations. We hypothesized that such an approach might help illuminate current issues in glioma research. To what degree are glioblastoma multiforme (GBM) cell lines representative of primary GBM tumors? We carried out a gene expression profiling study using cDNA array technology on 10 GBM primary tissues and 3 GBM cell lines. The gene expression levels were quantified, and the within-subject ranks of the gene expression levels were subsequently evaluated by hierarchical clustering analysis, multidimensional scaling analysis, and principal component analysis. Hierarchical cluster analysis shows that the 3 cell lines form one main cluster and the 10 tissue samples form a separate cluster. Multidimensional scaling and principal components analysis provided further graphical demonstration that the cell lines are clearly different from the tissue samples and that the cell lines are more different between themselves than are the tissues.

Central Nervous System Neoplasms↗
PubMed1999

HLA genes and haplotypes in Ryukyuans suggest recent gene flow to the Okinawa Islands.

Polymorphism of HLA genes was investigated in a population sample of Ryukyuans living on the main island of Okinawa (n = 197), in the southwestern islands of Japan. Serological typing was applied to class I loci (HLA-A, -B, and -C) and to HLA-DRB1; nucleotide sequence-level typing was performed using PCR microtiter plate hybridization and PCR single-strand conformation polymorphism methods. Ryukyuans showed a higher frequency of DRB1*0405 and lower frequencies of DRB1*1502 and DRB1*1302 compared with Hondo Japanese living on main islands. Principal components and phylogenetic analyses of 12 East Asian populations, including Ryukyuans, were performed based on the allele frequencies of HLA-A, -B, and -DRB1. In the principal components analysis 3 Japanese populations (Ryukyuans, Hondo Japanese, and Ainu) formed a cluster and showed the highest affinity to 2 Korean populations. In the phylogenetic tree Ryukyuans and Ainu were neighbors, but the genetic distance between them was larger than the distances between Ryukyuans and Hondo Japanese and between Ryukyuans and Korean populations. The geographic cline of the predominant haplotype in Ryukyuans, A*24-B*54-DRB1*0405, suggests that an ancestral population possessing A*24-B*54-DRB1*0405 moved into the Okinawa Islands after the divergence of Ryukyuans from the Ainu. Such a recent gene flow, probably from South China to the Okinawa Islands, is considered the major cause of difference in genetic characteristics between Ryukyuans and the Ainu.

Adult↗
PubMed2003

Dimension reduction for physiological variables using graphical modeling.

In intensive care, physiological variables of the critically ill are measured and recorded in short time intervals. The proper extraction and interpretation of the essential information contained in this flood of data can hardly be done by experience alone. Typically, decision making in intensive care is based on only a few selected variables. Alternatively, for a dimension reduction statistical latent variable techniques like principal component analysis or factor analysis can be applied. However, the interpretation of latent components extracted by these methods may be difficult. A more refined analysis is needed to provide suitable bedside decision support. Graphical models based on partial correlations provide information on the relationships among physiological variables that is helpful for variable selection and for identifying interpretable latent components. In a comparative study we investigate how much of the variability of the observed multivariate physiological time series can be explained by variable selection, by standard principal component analysis and by extracting latent compo-nents from groups of variables identified in a graphical model.

Aged↗
PubMed1995

Taxonomy of lactic acid bacteria associated with vacuum-packaged processed meat spoilage by multivariate analysis of cellular fatty acids.

The taxonomy of lactic acid bacteria from vacuum-packaged processed meats is problematic, and atypical members of the leuconostocs and the Lactobacillus sake / curvatus group are often encountered. In order to resolve this problem the cellular fatty acid (CFA) content of 61 isolates from vacuum-packaged vienna sausages and 18 reference strains was determined by gas chromatography. The relationship between strains was derived by principal component analysis of data. The CFA profiles were highly reproducible. Although no relationships could be derived using only one or two differentiating CFAs, plots of the first two principal components based on only the six most variable CFAs allowed grouping of strains. The two genera (Leuconostoc and Lactobacillus) could not be clearly separated when analysed together, but differentiation of species within each of the genera was achieved when they were analysed independently. Examination of plots for the reference strains confirmed previously established relationships between these strains. From the plot of the Lactobacillus sake / Lactobacillus curvatus component of the study it was found that most atypical Lactobacillus sake / curvatus strains were closely related to the typical Lactobacillus sake isolates and reference strain, while the Lactobacillus curvatus strains formed an independent grouping. A small cluster of atypical strains, however, indicated that this relationship may not be true for all these strains. Among the leuconostocs only isolates of Leuconostoc mesenteroides could be clearly differentiated.

Fatty Acids↗
PubMed2005

The equilibrium unfolding of MerP characterized by multivariate analysis of 2D NMR data.

A general problem when analysing NMR spectra that reflect variations in the environment of target molecules is that different resonances are affected to various extents. Often a few resonances that display the largest frequency changes are selected as probes to reflect the examined variation, especially in the case, where the NMR spectra contain numerous resonances. Such a selection is dependent on more or less intuitive judgements and relying on the observed spectral variation being primarily caused by changes in the NMR sample. Second, recording changes observed for a few (albeit significant) resonances is inevitably accompanied by not using all available information in the analysis. Likewise, the commonly used chemical shift mapping (CSM) [Biochemistry 39 (2000) 26, Biochemistry 39 (2000) 12595] constitutes a loss of information since the total variation in the data is not retained in the projection into this single variable. Here, we describe a method for subjecting 2D NMR time-domain data to multivariate analysis and illustrate it with an analysis of multiple NMR experiments recorded at various folding conditions for the protein MerP. The calculated principal components provide an unbiased model of variations in the NMR spectra and they can consequently be processed as NMR data, and all the changes as reflected in the principal components are thereby made available for visual inspection in one single NMR spectrum. This approach is much less laborious than consideration of large numbers of individual spectra, and it greatly increases the interpretative power of the analysis.

Fourier Analysis↗
PubMed2002

Psychological impact of erectile dysfunction: validation of a new health related quality of life measure for patients with erectile dysfunction.

PURPOSE: Male erectile dysfunction has a substantial impact on health related quality of life. We examined the psychometric properties of 2 new scales created to measure the psychological impact of erectile dysfunction. MATERIALS AND METHODS: Patients enrolled in a long-term study of men with erectile dysfunction completed clinical and health related quality of life information at baseline and at 3 followup points. The questionnaire incorporated a number of standard scales of psychosocial characteristics as well as questions developed from comments made during focus groups of men with erectile dysfunction and of their female partners. Principal components analysis was used to identify underlying constructs in response to the new questions. RESULTS: A total of 168 men completed the baseline quality of life questionnaire. The principal components analysis of the psychological impact of erectile dysfunction questions resulted in 2 new scales. Reliability was good with an internal consistency reliability of 0.91 for scale 1 and 0.72 for scale 2. Test-retest reliability was 0.76 and 0.66, respectively. Men reporting a greater psychological impact of erectile dysfunction also reported greater impairment in functional status, lower sexual self-efficacy, greater depression and anxiety at the last intercourse. Each new scale significantly differentiated men with mild/moderate versus severe erectile dysfunction. CONCLUSIONS: We developed 2 new scales to measure the psychological impact of erectile dysfunction and they showed good reliability and validity. These new scales, named the Psychological Impact of Erectile Dysfunction instrument, comprehensively capture the psychological effect of erectile dysfunction on health related quality of life, which is not adequately assessed by existing patient centered measures of erectile function.

Adult↗
PubMed1999

Application of multivariate data analysis methods to comparative molecular field analysis (CoMFA) data: proton affinities and pKa prediction for nucleic acids components.

Multivariate data analysis methods (Principal Component Analysis (PCA) and Partial Least Squares (PLS)) are applied to the analysis of the CoMFA (Comparative Molecular Field Analysis) data for several nucleic acids components. The data set includes nitrogenated bases, nucleosides, linear nucleotides, 3', 5'-cyclic nucleotides and oligonucleotides. PCA is applied to study the structure of the CoMFA data and to detect possible outliers in the data set. PLS is applied to correlate the CoMFA data with either calculated AM1 proton affinities or with experimental pKa values. The possibility of making a prediction of pKa values directly from 3D structures of the monomers for polynucleotides is also shown. The influence of the superposition criteria and of conformational changes along the glycosidic bond on the pKa prediction are studied as well.

Glycosylation↗
PubMed1980

Development of a new inventory assessing memories of parental rearing behaviour.

A new inventory (EMBU) to assess the own memories of parental rearing behaviour was constructed. EMBU is comprised of 81 questions grouped in 15 subscales and two additional questions referring to consistency and strictness of parental rearing behaviour to be answered in a four-step scale for the father and for the mother separately. The subscales cover rearing practices as for eexample overinvolment, affection, overprotectiveness, guilt engendering, rejection. 152 healthy subjects of both sexes (108 males and 44 females) completed the inventory. The item analysis showed that both parents attained similar scores in about half of the questions. Fathers scored higher in items referring to strictness, punishment and a low degree of involvement whereas mothers scored higher in items referring to involvement and affection. A principal component factor analysis permitted the hypothesized subscales to be identified. An analysis of the internal consistency of the subscales revealed a high frequency of significant internal correlations. A principal component factor analysis of the total scores of the 15 subscales allowed three main dimensions of rearing behaviour to be identified quite close to those reported in similar studies in the literature where other scales had been used.

Child↗
PubMed2003

Intelligent data analysis to interpret major risk factors for diabetic patients with and without ischemic stroke in a small population.

This study proposes an intelligent data analysis approach to investigate and interpret the distinctive factors of diabetes mellitus patients with and without ischemic (non-embolic type) stroke in a small population. The database consists of a total of 16 features collected from 44 diabetic patients. Features include age, gender, duration of diabetes, cholesterol, high density lipoprotein, triglyceride levels, neuropathy, nephropathy, retinopathy, peripheral vascular disease, myocardial infarction rate, glucose level, medication and blood pressure. Metric and non-metric features are distinguished. First, the mean and covariance of the data are estimated and the correlated components are observed. Second, major components are extracted by principal component analysis. Finally, as common examples of local and global classification approach, a k-nearest neighbor and a high-degree polynomial classifier such as multilayer perceptron are employed for classification with all the components and major components case. Macrovascular changes emerged as the principal distinctive factors of ischemic-stroke in diabetes mellitus. Microvascular changes were generally ineffective discriminators. Recommendations were made according to the rules of evidence-based medicine. Briefly, this case study, based on a small population, supports theories of stroke in diabetes mellitus patients and also concludes that the use of intelligent data analysis improves personalized preventive intervention.

Brain Infarction↗
PubMed2003

Adaptation of the MacNew quality of life questionnaire after myocardial infarction in an Iranian population.

BACKGROUND: Health-related quality of life (HRQL) assessment is an important measure of the impact of a wide range of disease process on an individual. To date, no HRQL tool has been evaluated in an Iranian population with cardiovascular disorders, specifically myocardial infarction, a major cause of mortality and morbidity. The MacNew Heart Disease Health-related Quality of Life instrument is a disease-specific HRQL questionnaire with satisfactory validity and reliability when applied cross-culturally. METHOD: A Persian version of MacNew was prepared by both forward and backward translation by bilinguals after which a feasibility test was performed. Consecutive patients (n = 51) admitted to a coronary care unit with acute myocardial infarction were recruited for measurement of their HRQL with retest one month after discharge in the follow-up clinic. Principal components analysis, intra-class correlation reliability, internal consistency, and test-retest reliability were assessed. RESULTS: Trivial rates of missing data confirmed the acceptability of the tool. Principal component analysis revealed that the three domains, emotional, social and physical, performed as well as in the original studies. Internal consistency was high and comparable to other studies, ranging from 0.92 for the emotional and physical domains, to 0.94 for the social domain, and to 0.95 for the Global score. Domain means of 5, 5.3 and 4.9 for emotional, physical and social respectively indicate that our Iranian population has similar emotional and physical but worse social HRQL scores. Test-retest analysis showed significant correlation in emotional and physical domains (P < 0.05). CONCLUSION: The Persian version of the MacNew questionnaire is comparable to the English version. It has high internal consistency and reasonable reproducibility, making it an appropriate specific quality of life tool for population-based studies and clinical practice in Iran in patients who have survived an acute myocardial infraction. Further studies are needed to confirm its validity in larger populations with cardiovascular disease.

Adult↗
PubMed1996

Comparison of the crown dimensions between the maxillary second deciduous molar and the first permanent molar.

The morphologic relationship of the crown structures of the maxillary second deciduous molar (m2) and the first permanent molar (M1) was investigated with odontometric methods. Materials used were 124 male dental casts taken from Chinese living in Kaohsiung (Taiwan). The mesiodistal and buccolingual diameters, cusp sizes, and intercusp distances were measured. The mean crown diameters were larger in M1 than in m2. The tooth crown proportions were similar in m2 and M1. The intercusp distance was compressed buccolingually in m2. With respect to the relative cusp size, the paracone was not significantly different between m2 and M1. The metacone was relatively larger in m2 than M1, while lingual cusps (protocone and hypocone) were relatively smaller in m2 than in M1. Principal component analysis was performed to investigate factors influencing the variation in crown dimensions of the two teeth. Four components were extracted: (1) buccolingual intercusp distances, (2) crown proportion (mesiodistal and buccolingual diameters), (3) mesiobuccal and distolingual compression, and (4) protocone and mesiodistal intercusp distance. Analysis of principal component scores indicated that the crown proportions of m2 and M1 were similar. The m2 had a smaller protocone and more buccolingually compressed intercusp distances than did M1. The morphologic characteristics of the crown of m2 indicate that it is more primitive and has developed less than M1.

Humans↗
PubMed2004

Midsagittal cranial shape variation in the genus Homo by geometric morphometrics.

Midsagittal profiles of crania referred to different taxa of the genus Homo have been analyzed by geometric morphometric techniques. Comparisons between single specimens using the thin-plate-spline function suggest a generalized reduction of the lower face, associated with antero-posterior development of the braincase occurring (possibly in parallel evolution) along distinct human lineages. Furthermore, Neandertals display a projection of the midface, and modern humans show a derived globularity of the vault associated with midsagittal parietal bulging. Principal Component Analysis demonstrates a bimodal pattern of variation, which describes an "archaic" pole (rather heterogeneous in terms of taxonomy) clearly distinguishable from the modern one. The first two principal components - that explain together 80% of the total variance in shape - involve respectively fronto-parietal expansion and midfacial prognathism. These results contribute to identify different structural patterns in human evolution, supporting discontinuity rather than continuity of cranial shape among different taxa of the genus Homo, especially when considering the differences between Neandertals and early modern humans.

Animals↗
PubMedDate not supplied

Estimating analytical variances in measurement of polycyclic aromatic hydrocarbons and application to monitoring contaminants in American lobster (Homarus americanus).

A method is presented for estimating replicate polycyclic aromatic hydrocarbon (PAH) concentrations in American lobster (Homarus americanus) digestive gland tissue based on recoveries of added perdeuterated surrogates from a single satisfactory analysis. PAH concentrations demonstrated a large interanimal variance, even in specimens captured at the same time in the same place. Principal component analysis showed that the variability of the total system of biological variables (carapace length, lobster weight, and digestive gland weight) could be adequately summarized by the first principal component alone in each data set. Ranks provide ordered classification of individuals, allowing data analysis by statistical methods for continuous variables (i.e., analysis of variance). PAH concentrations in individual lobsters were generally highly sensitive to animal size, sex, and fishing area. Efficient monitoring would result from analyzing individual animals of a single sex from a study area, using as small a geographical study area as possible, measuring a single biological variable, and using individual specimens of as narrow a size range as possible.

Analysis of Variance↗
PubMed2005

Development of a ligand knowledge base, part 1: computational descriptors for phosphorus donor ligands.

A prototype collection of knowledge on ligands in metal complexes, termed a ligand knowledge base (LKB), has been developed. This contribution describes the design of DFT-calculated descriptors for monodentate phosphorus(III) donor ligands in a range of representative complexes. Using the resulting data, a ligand space is mapped and predictive models are derived for metal complexes. Important characteristics, including chemical, computational and statistical robustness for the generation and exploitation of such an LKB are described. Chemical robustness ensures transferability of the descriptors, as well as comprehensive sampling of ligand space. To make the calculations amenable to automation in an e-science setting, a reliable, well-defined computational approach has been sought from which the descriptors can be readily extracted. The LKB has been explored with multivariate statistical methods. Principal component analysis (PCA) is used for the mapping of chemical space, projecting multiple descriptors into scatter plots which illustrate the clustering of chemically similar ligands. Interpretation of the resulting principal components in terms of established steric and electronic properties and the importance of its statistical robustness to variations in the ligand set are discussed. Multiple linear regression (MLR) models have been derived, demonstrating the versatility of the descriptors for modeling varied experimentally determined parameters (bond lengths, reaction enthalpies and bond-stretching frequencies). The importance of re-sampling methods for testing the robustness of predictions is highlighted. A strategy for the construction of a robust LKB suitable for the modeling of ligand and complex behavior is outlined based on these observations.

Journal Article↗
PubMed1993

Development of a fatigue scale.

A self-rating scale was developed to measure the severity of fatigue. Two-hundred and seventy-four new registrations on a general practice list completed a 14-item fatigue scale. In addition, 100 consecutive attenders to a general practice completed the fatigue scale and the fatigue item of the revised Clinical Interview Schedule (CIS-R). These were compared by the application of Relative Operating Characteristic (ROC) analysis. Tests of internal consistency and principal components analyses were performed on both sets of data. The scale was found to be both reliable and valid. There was a high degree of internal consistency, and the principal components analysis supported the notion of a two-factor solution (physical and mental fatigue). The validation coefficients for the fatigue scale, using an arbitrary cut off score of 3/4 and the item on the CIS-R were: sensitivity 75.5 and specificity 74.5.

Adult↗