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PubMed2005

Principal component analysis of some oxidative stress parameters and their relationships in hemodialytic and transplanted patients.

BACKGROUND: Oxidative stress profoundly influences the biochemistry of proteins and many other molecules in tissues of uremic patients. In three different groups of uremic patients, the concentrations of the free and bound pentosidine and low-molecular-weight-advanced glycoxydation end products (LMW-AGEs), carbonyls (LMW-C), advanced oxidation protein products (AOPP) and the total antioxidant power of serum were studied in order to determine the relationships between these factors in hemodialytic and transplanted patients. PATIENTS AND METHODS: The above-mentioned parameters were determined in 10 subjects who were currently in hemodialysis (HD) treatment, 10 kidney transplanted patients with chronic renal failure (Tx-CRF), 10 kidney transplanted patients with normal renal function (Tx-N) and 10 healthy subjects (Ctr). The data matrix (40x7) was analyzed using the principal component analysis (PCA). RESULTS: AGEs, carbonyls and AOPP were strongly correlated, while the total antioxidative serum capacity was not related to the other oxidative stress parameters. All the oxidative stress-related parameter values (AGEs, AOPP and LMW-C) in the Tx patients were similar to those of the control group, but were higher in the patients with chronic renal failure. CONCLUSIONS: The correlation between early and advanced oxidative stress markers indicates that reactive oxygen species are involved in a common step in the mechanism of protein modification in all the patient examined. The relationships between carbonyls and AGEs (free, bound pentosidine and LMW-AGEs) support the hypothesis of "carbonyl stress". The common mechanism of the formation of oxidation products in healthy and diseased subject suggests their role of detoxification within kidney function. The total antioxidant power of the serum is not related to the other parameters, which indicates a possible role of molecule interfering.

Antioxidants↗
PubMed2006

Ambient air particulate concentrations and metallic elements principal component analysis at Taichung Harbor (TH) and WuChi Traffic (WT) near Taiwan Strait during 2004-2005.

The purpose of this study is to characterize metallic elements associated with atmospheric particulate matter of total suspended particulate (TSP), fine particle (particle matter with aerodynamical diameter <2.5 microm, PM(2.5)), coarse particle (particle matter with aerodynamical diameter 2.5-10 microm, PM (2.5-10)) at the Taichung Harbor (TH) and WuChi Traffic (WT) sampling site of central Taiwan during March 2004 to February 2005. The result indicated the average total suspended particulate concentration in 1 year was 157.31 and 112.58 microg m(-3) at TH and WT sampling site, respectively. Fine particle (PM(2.5)) size was the dominant species at TH and WT sampling site. In TH sampling site, higher correlation coefficient was observed on total suspended particulates of metallic elements Fe and Zn. And in WT sampling site, higher correlation coefficients displayed on total suspended particulates of metallic elements Fe and Zn, Fe and Mn. Ambient airborne particle principal component analysis of metallic metals was used to identify the possible pollutant sources in this study. At the TH sampling site, 50.81% of the total variance of the data was observed in factor 1. Higher loading of Fe (0.86), Zn (0.79), Pb (0.76), and Mn (0.68) were contributed by traffic emission and the soil source. At the WT sampling site, factor 1 explained 53.74% of the total variance of the data and had high loading for Zn (0.86) and Cu (0.85), which were identified as industrial/traffic emission sources.

Air↗
PubMed2006

Monte Carlo sampling and principal component analysis of flux distributions yield topological and modular information on metabolic networks.

The work presented here uses Monte Carlo random sampling combined with flux balance analysis and linear programming to analyse the steady-state flux distributions on the surface of the glucose-ammonia phenotypic phase plane of an Escherichia coli system grown on glucose-minimal medium. The distribution of allowable glucose and ammonia uptake rates showed a triangular shape, the apex corresponding to maximum growth rate. The exact shape, e.g. the diagonal boundary is determined by the relative amounts of nutrients required for growth. The logarithm of flux values has a normal distribution, e.g. there is a log normal distribution, and most of the reactions have an order of magnitude between 10(-1) and 1. The increase in the number of blocked reactions as growth switched from aerobic to micro-aerobic phase and the presence of alternate networks for a single optimal solution were both reflections of the variability of pathway utilization for survival and growth. Principal component analysis (PCA) provided us with significant clues on the correlations between individual reactions and correlations between sets of reactions. Furthermore, PCA identified the most influential reactions of the system. The PCA score plots clearly distinguish two different growth phases, micro-aerobic and aerobic. The loading plots for each growth phase showed both the impact of the reactions on the model and the clustering of reactions that are highly correlated. These results have proved that PCA is a promising way to analyse correlations in high-dimensional solution spaces and to detect modular patterns among reactions in a network.

Ammonia↗
PubMed2004

Class separation of buildings with high and low prevalence of SBS by principal component analysis.

In this study, we were able to separate buildings with high and low prevalence of sick building syndrome (SBS) using principal component analysis. The prevalence of SBS was defined by the presence of at least one typical skin, mucosal and general (headache and fatigue) symptom. Data from the Swedish Office Illness Study describing the presence and level of chemical compounds in outdoor, supply, and room air, respectively, were evaluated together with information about the buildings in six models. When all data were included the most complex model was able to separate 71% of the high prevalence buildings from the low prevalence buildings. The most important variable that separates the high prevalence buildings from the low prevalence buildings was a more frequent occurrence or a higher concentration of compounds with shorter retention time in the high prevalence buildings. Elevated relative humidity in supply and room air and higher levels of total volatile organic compounds in outdoor and supply air were more common in high prevalence buildings. Ten building variables also contributed to the separation of the two classes of low and high prevalence buildings.

Air Pollutants↗
PubMed1994

Principal components of fitness: relationship to physical activity and lifestyle.

Interrelationships between metabolic and cardiorespiratory health were examined in 350 healthy adults. Four principal components accounted for 66.7% of the variance in 172 males (M) and for 62.4% in 178 females (F). Factor 1, "obesity," related to body mass index, abdominal circumference, total skinfold thickness, and (M only) abdominal/hip circumference ratio. Factor 2, "cardiovascular fitness," had loadings from resting heart rate and PWC150/kg. Factors 3 and 4 were related to total cholesterol and HDL-cholesterol, respectively (plus blood pressures, particularly in F). Factor 1 was linked to caffeine consumption and to exercise frequency (F) or perceived intensity (M). Factor 2 was linked to perceptions of activity relative to others (M and F) and to the intensity of activity (M only). Factors 3 and 4 were associated with perceived fitness and physical activity relative to others. Because perceptions of physical activity and fitness lack consistency, it is suggested that health be judged more directly from simple measures of health related fitness that require little subject cooperation.

Adult↗
PubMed2005

The role of the right hemisphere in processing nonsalient metaphorical meanings: application of principal components analysis to fMRI data.

Some researches indicate that the right hemisphere (RH) has a unique role in comprehending the figurative meaning of metaphors whereas the results of other studies do not support the notion of a selective role for the RH in accessing metaphorical meanings. The present research used fMRI technology to test a theoretical explanation of the above conflicting findings. This theoretical account is derived from the Graded Salience Hypothesis (GSH) [Giora, R. (1997). Understanding figurative and literal language: the Graded Salience Hypothesis. Cognitive Linguistics, 7, 183-206; Giora, R. (2003). On our mind: Salience, context and figurative language. New York: Oxford University Press], according to which the degree of meaning salience, rather than literality or nonliterality primarily affects differences between the LH and RH in linguistic processing. Thus, the GSH predicts a selective RH involvement in comprehension of novel, nonsalient metaphoric meanings and LH involvement in the comprehension of conventional, salient metaphoric meanings. Fifteen normal adults participated in a block designed fMRI experiment that compared the patterns of brain activation induced by processing the meanings of literal, conventional metaphoric, novel metaphoric and unrelated word pairs. The subjects performed a semantic judgment task. We applied the Principal Components Analysis (PCA) technique in order to find different functional networks corresponding to the different stimuli. Our results, obtained from PCA of the fMRI data indicate that the right homologue of Wernicke's area has a special role in processing novel metaphors. We suggest that a unique network, consisting of the right homologue of Wernicke's area, right and left premotor areas, right and left insula and Broca's area, is recruited for the processing of novel metaphors but not for the processing of conventional metaphors.

Adult↗
PubMed2005

Distribution of PCDDs and PCDFs in soils collected from the Denver Front Range--principal components analysis of diffuse dioxin sources.

BACKGROUND, AIMS AND SCOPE: The Rocky Mountain Arsenal (RMA) is a U.S. Army facility located northeast of Denver, Colorado that has been listed on the National Priorities List (NPL). It is currently being re-mediated under the authority of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and the Superfund Amendments and Reauthorization Act of 1986 (SARA). As part of the remediation activities at RMA, indications were found that a source of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) had existed on the RMA. As a result, investigations were undertaken to assess the possible nature and extent of any potential sources of PCDDs and PCDFs on the RMA site. In addition, other studies were conducted that examined PCDD/PCDF contamination in the Denver area. The goal of these studies was to examine nature and extent of PCDD/PCDF contamination both on the RMA as well as in the surrounding Denver area. The intent of this study was to characterize sources of dioxins (PCDDs) and dibenzofurans (PCDFs) at low environmental concentrations which might have originated from diffuse sources in the Denver Colorado area and in particular, the Rocky Mountain Arsenal (RMA) using Principal Component Analysis (PCA). METHODS: Over 200 soil samples were collected from the RMA and the Denver area. From the RMA, soil was collected as part of three studies that included a (1) random site-wide sampling of the RMA, (2) soils from the Western Tier Parcel (WTP), and (3) soils from Historic Use areas. Denver area soil samples were collected from five different land use categories: Residential, Agricultural, Open Space, Commercial, and Industrial. PCA was conducted on concentrations of 17 2,3,7,8-substituted PCDD and PCDF congeners in 220 soil samples collected from the RMA and the Denver Front Range region. RESULTS AND DISCUSSION: PCA demonstrated the presence of possible minor sources of dioxins on the RMA. Current remediation efforts on RMA will result in the removal of these sources. Samples from the RMA were identified by the presence of a congener profile containing higher chlorinated PCDFs while the Denver Front Range areas were characterized by the presence of higher chlorinated PCDD congeners. The presence of a PCDF signature for the RMA samples does not necessarily indicate a major source of these contaminants on-site. Indeed, the relatively diffuse nature of the sample clusters would argue strongly against the presence of a single large source. Instead, the predominance of the PCDF congeners probably indicates the mixed industrial activities that took place on and near the site. CONCLUSION: PCA results indicate that PCDD/PCDF profiles in soils collected from the RMA differed from those collected from the outlying Denver areas but that a major source of these contaminants was not present. Rather, the diffuse nature of sample clusters from the PCA indicated that the congener profile of RMA samples was most likely a result of the mixed industrial activities that historically have taken place on and near the site. PCA also indicated that many of the 'open area' (peripheral site-wide) RMA soils samples did not differ from Denver are reference congener profiles. This finding was also true for samples collected from the WTP that were essentially indistinguishable from Off-RMA reference samples. In addition, total TEQ concentrations in soils collected from WTP were similar to those measured in soils collected from the Denver Front Range areas indicating that lack of a major source of PCDD/PCDF within the WTP zones of the RMA. RECOMMENDATION AND OUTLOOK: Analytical as well as statistical results of the soil congener data indicate that the WTP soils are indistinguishable from soils collected from non-industrial areas in the Denver area. This finding would support the recent 'de-listing' of the WTP from the other RMA areas and its transfer to other authorities in the Denver area.

Benzofurans↗
PubMed1985

The use of principal component analysis to resolve the spectra and kinetics of cytochrome c oxidase reduction by 5,10-dihydro-5-methyl phenazine.

The method of principal component analysis (PCA) was applied to the absorption-wavelength-time surfaces generated by rapid scanning stopped-flow spectrophotometry (RSSFS). The method was used to resolve the absorption surfaces generated during the reduction of cytochrome c oxidase by 5,10-dihydro-5-methyl phenazine (MPH) into the individual spectral shapes and time courses of the component chromophores. Two forms of resting cytochrome oxidase were used in these analyses: one that has its maximum absorption in the Soret region at 418 nm (418-nm species) and the other has its absorption maximum at 424 nm (424-nm species). A weighting scheme suitable for RSSFS data was developed. The optical absorption spectra obtained by W.H. Vanneste (1966, Biochemistry, 5:838-848) for the oxidase components were found to fit adequately as components of the experimental surfaces. Among these spectra were the oxidized forms of cytochromes a and a3 in the wavelength region 330-520 nm for the 418-nm species. Vanneste's spectral shape for the oxidized cytochrome a3 did not fit as a component in the spectrum of the 424-nm species. After accounting for the spectral shape of all components present, PCA provided a straightforward method for determining the separate time courses of each chromophore. We have found for both forms used that cytochrome a is reduced by MPH in the initial stages of the reaction, while cytochrome a3 is reduced in subsequent, slow phases. An important aspect of PCA is that it provided confirmation of the spectra of the various oxidase components without requiring the use of inhibitors or the use of simplifying mechanistic assumptions. The resolution of time profiles of strongly overlapping chromophores is also demonstrated.

Electron Transport Complex IV↗
PubMed1999

Validation of a right hemisphere vigilance system as measured by principal component and factor analyzed quantitative electroencephalogram.

Arruda and colleagues [Arruda, J.E., Weiler, M.D., Valentino, D.A. et al., 1996. A guide for applying principal-component analysis and confirmatory factor analysis to qEEG data. Int. J. Psychophysiol. 23, 63-81.] recently described seven neurophysiological measures that were previously derived and confirmed using factor analytic procedures and the quantitative electroencephalogram (EEG) sampled from 208 normal controls during an auditory continuous performance test (CPT). The purpose of the present investigation was to further test the validity of these empirically derived measures by examining each measure's relationship with CPT-related declines in performance. Participants were 48 right-handed men (n = 13) and women (n = 35) who reported being free of any neurological condition, birthing complications, or loss of consciousness greater than 2 min. After completing an eyes-closed resting condition, participants performed a 23-min CPT while both quantitative EEG and behavioral performance were measured at 45, 405, 765 and 1125 s into the CPT. Bipolar recordings were gathered using the International 10-20 system, from eight sites: frontal, fronto-temporal, temporal and temporal-occipital. Multivariate and follow-up univariate tests suggest the existence of a neurophysiological system located within the right temporal region that appears essential for the maintenance of a sustained attentional state. If confirmed, the further quantification of this neurocognitive system may prove useful as part of a clinical diagnostic workup.

Adolescent↗
PubMed1987

Self-reports of eating behavior, goals, imagery, and health status: principal components and sex differences.

University students (N = 208) completed a questionnaire on four aspects of eating: behavior, goals, imagery, and health status. A principal components analysis of the 18 self-report variables identified six factors: Weight Control Failure, Sensory Awareness of Food and Eating, Stable Eating Pattern, Unrestrained Overeating, "Home Cooking and Good Digestion," and Environmental Indifference. Sex differences in self-reporting were statistically significant on 10 of the 18 variables, with 6 of those significant variables heavily loaded on the first factor: Weight Control Failure. Analysis of these variables suggests that women report eating to be more problematic than do men. Several of the aspects of self-reports are discussed, including the apparent independence of sensory awareness of food and eating from self-reports of behavior, goals, and health status.

Adult↗
PubMed1975

Principal component analysis of infraspecific variation in bacteria.

In certain types of ecological investigations it may be desirable to investigate infraspecific variation in bacteria. Principal component analysis is demonstrated to be satisfactory for this purpose. Hypothetical bacterial populations were used to show that such analysis can be used to compare collections of bacterial isolates taken at different times or from different sources. Alternatively, given n isolates, whether they represent a single bacterial population can be determined. The method is applied to authentic collections of bacteria in three separate analyses. The results are compatible with current taxonomic tenets.

Bacteria↗
PubMed2003

Use of principal component analysis to investigate the origin of heptadecenoic and conjugated linoleic acids in milk.

The aim of this paper was the application of principal component analysis (PCA) 1) to elucidate mutual metabolic relationships between milk fatty acids (FA) and 2) to illustrate the origin of milk FA, in particular C17:1 and cis-9,trans-11 conjugated linoleic acid. Data were combined from 3 experiments with lactating Holstein-Friesian cows offered diets based on grass or legume silage and concentrates. Loading plots of PCA based on milk FA concentrations showed 4 groups of milk FA, having similar precursors or metabolic pathways in the rumen and/or mammary gland: medium-chain saturated FA, de novo synthesized from acetate and beta-hydroxybutyrate; monoenoic milk FA, products of delta9-desaturase activity in the mammary gland; odd chain FA of rumen microbial origin and C18:0, n-6 C18:2, and n-3 C18:3 of dietary origin or the result of rumen biohydrogenation. Loading plots of PCA based on both milk and duodenal FA concentrations as well as on milk FA yields and duodenal FA flows further illustrated the importance of postabsorptive synthesis of the milk medium chain saturated and monoenoic FA and the direct absorption from the blood stream of odd chain FA, C18:0, n-6 C18:2, and n-3 C18:3. In all loading plots, milk oleic acid (C18:1) appeared intermediate between clusters of 18-carbon FA and monoenoic FA, illustrating its dual (dietary and endogenous production) origin. Milk C17:1 was suggested to be a desaturation product of C17:0, in common with other milk monoenoic FA. Finally, the PCA technique, based on milk FA patterns of one experiment, was applied to investigate factors determining cis-9,trans-11 conjugated linoleic acid concentrations in milk. Within the range of diets and cows studied here, we showed changes in cis-9,trans-11 conjugated linoleic acid to be mainly dependent on vaccenic acid supply and to a lesser extent on variation in desaturase activity.

3-Hydroxybutyric Acid↗
PubMed1989

Doubts on the adequacy of the principal component varimax analysis for the identification of event-related brain potential components: a commentary on Glaser and Ruchkin, and Donchin and Heffley.

Glaser and Ruchkin (1976) as well as Donchin and Heffley (1978) have proposed principal component varimax analysis (PCVA) for identification of event-related potential (ERP) components. In the present commentary, the assumptions on the ERP data structure of this procedure are considered. They are formalized and compared with a simpler and more restrictive hypothesized ERP data structure containing autoregressive properties. Referring to the principle of parsimony, the comparison of the two models shows the superiority of the hypothesized autoregressive structure: to fit a set of ERP data equally well, the autoregressive structure does so with considerably more parsimonious assumptions, i.e. with fewer parameters to be estimated, than the structure induced by PCVA. It is concluded that an appropriate model for the ERP data structure should take the autocorrelated nature of the ERP into account.

Contingent Negative Variation↗
PubMedDate not supplied

Identification of drugs by principal components analysis of Rf data obtained by TLC in different eluent systems.

The retention factor of 54 drugs in eight eluent mixtures is reported. Principal component analysis (PCA) of these data provided a significant two-components model. These two parameters characteristic for each drug allowed an objective identification of unknown samples, provided they were included in the considered set. The analysis showed that the eluent mixtures cluster into three groups. The PCA model, using only three eluents (one for each group), was also able to restrict the range of inquiry to a few "candidates" and, in some cases, to allow unambiguous identification of the drug. These results, based on a simple and quick analytical determination (thin layer chromatography) and a reliable statistical procedure (PCA), appear to be of significant practical importance in the field of analytical toxicology.

Chromatography, Thin Layer↗
PubMed1997

Principal Component and Neural Network Analyses of Face Images: What Can Be Generalized in Gender Classification?

We present an overview of the major findings of the principal component analysis (pca) approach to facial analysis. In a neural network or connectionist framework, this approach is known as the linear autoassociator approach. Faces are represented as a weighted sum of macrofeatures (eigenvectors or eigenfaces) extracted from a cross-product matrix of face images. Using gender categorization as an illustration, we analyze the robustness of this type of facial representation. We show that eigenvectors representing general categorical information can be estimated using a very small set of faces and that the information they convey is generalizable to new faces of the same population and to a lesser extent to new faces of a different population. Copyright 1997 Academic Press. Copyright 1997 Academic Press

Journal Article↗
PubMed2001

Analysis of galvanic skin responses with principal components and clustering techniques.

An advanced method for analyzing the patterning of successive galvanic skin responses (GSR) is presented. The proposed method is based on principal component analysis in which the vector containing the measured signal is presented as a weighted sum of orthogonal basis vectors. The method is tested using measurements from 20 healthy controls and 13 psychotic patients. For each subject, 11 surprising auditory stimuli were delivered to right ear at irregular intervals and evoked GSRs were recorded from the hand. For most of the healthy controls, there was a clear pattern in successive GSRs, whereas within psychotic patients the lack of time-locking of GSRs seemed to be characteristical. These between group differences can be revealed by the proposed method. With application to clustering a significant discrimination, with overall correct ratings of 82%, of healthy controls and psychotic patients is achieved. A significant fact is that all patients were ranked correctly giving the proposed method a sensitivity of 100%.

Case-Control Studies↗
PubMed2002

Nonnegative color spectrum analysis filters from principal component analysis characteristic spectra.

Nonnegative color analysis filters are obtained by using an invertible linear transformation of characteristic spectra, which are orthogonal vectors from a principal component analysis (PCA) of a representative ensemble of color spectra. These filters maintain the optimal compression properties of the PCA scheme. Linearly constrained nonlinear programming is used to find a transformation that minimizes the noise sensitivity of the filter set. The method is illustrated by computing analysis and synthesis filters for an ensemble of measured Munsell color spectra.

Journal Article↗
PubMed1987

[Age-related changes in human body proportions studied by the method of principal components].

The method for analysis of the ontogenetic changes of size and shape based on the decomposition of Kullback divergence into parts corresponding to the principal components, found for intragroup variability of signs is suggested. The application of this method is illustrated by the analysis of age changes of body proportions for boys 3-17 years old. Before the pubertal period the stable tendency to a relative lengthening of extremities which changes to a contrast one at age of 12-14 has been pointed out. The definitive differences of proportions to a considerable extent is determined by variability of biological age at the group of children.

Adolescent↗