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PubMed1997

Identification and correlation of human footfall load parameters using multivariate analysis.

This research had two main objectives: to identify and quantify the multiple reaction parameters of human footfall load histories for 24 subjects; and to seek statistical correlations of the reaction parameters with two gaits: fitness walking and running, with two footfall surfaces: rigid and mat, and with two subject attributes: gender and arch index. These reaction parameters, measured with a force plate, include the subjects' foot reaction forces in the three orthogonal directions and the particular features of these forces such as their duration, average values, peak values, and rates of loading. An automated data retrieval-software system evaluated these reaction parameters. The statistical correlations were made using principal component analysis (PCA), a method that projected the 13 identified footfall reaction parameters onto subsets of three or four parameters called principal components that contained most of the variance of the original thirteen. The results, among others, show couplings between the vertical and the peak medial load, but an uncoupling of the posterior-anterior loads with the loads in the other two directions.

Adult↗
PubMed2005

Assessment of NIR spectroscopy for nondestructive analysis of physical and chemical attributes of sulfamethazine bolus dosage forms.

The goal of this study was to assess the utility of near infrared (NIR) spectroscopy for the determination of content uniformity, tablet crushing strength (tablet hardness), and dissolution rate in sulfamethazine veterinary bolus dosage forms. A formulation containing sulfamethazine, corn starch, and magnesium stearate was employed. The formulations were wet granulated with a 10% (wt/vol) starch paste in a high shear granulator and dried at 60 degrees C in a convection tray dryer. The tablets were compressed on a Stokes B2 rotary tablet press running at 30 rpm. Each sample was scanned in reflectance mode in the wavelengths of the NIR region. Principal component analysis (PCA) of the NIR tablet spectra and the neat raw materials indicated that the scores of the first 2 principal components were highly correlated with the chemical and physical attributes. Based on the PCA model, the significant wavelengths for sulfamethazine are 1514, (1660-1694), 2000, 2050, 2150, 2175, 2225, and 2275 nm; for corn starch are 1974, 2100, and 2325 nm; and for magnesium stearate are 2325 and 2375 nm. In addition, the loadings show large negative peaks around the water band regions ( approximately 1420 and 1940 nm), indicating that the partial least squares (PLS) models could be affected by product water content. A simple linear regression model was able to predict content uniformity with a correlation coefficient of 0.986 at 1656 nm; the use of a PLS regression model, with 3 factors, had an r (2) of 0.9496 and a standard error of calibration of 0.0316. The PLS validation set had an r (2) of 0.9662 and a standard error of 0.0354. PLS calibration models, based on tablet absorbance data, could successfully predict tablet crushing strength and dissolution in spite of varying active pharmaceutical ingredient (API) levels. Prediction plots based on these PLS models yielded correlation coefficients of 0.84 and 0.92 on independent validation sets for crushing strength and Q(120) (percentage dissolved in 120 minutes), respectively.

Compressive Strength↗
PubMed2006

Flavonoid composition of fruit tissues of citrus species.

An HPLC analysis was performed on the concentrations of flavonoids in 42 species and cultivars of the Citrus genus and those of two Fortunella and one Poncirus species according to the classification system established by Tanaka. The composition of 8 flavanones and 9 flavone/ols for these species was determined in the albedo, flavedo, segment epidermis and juice vesicle tissues, and those in the fruit and peel tissues were calculated from the composition data of the tissues. A principal component analysis showed that such neohesperidosyl flavonoids as neoeriocitrin, naringin, neohesperidin, and rhoifolin had large factor loading values in the first principal component for each tissue. The flavonoid composition of citrus fruits was approximately the same within each section of Tanaka's system, except for the species in the Aurantium section and those with a peculiar flavonoid composition such as Bergamot (C. bergamia), Marsh grapefruit (C. paradisi), Sour orange (C. aurantium), and Shunkokan (C. shunkokan). The Aurantium section included both naringin-rich and hesperidin-rich species.

Citrus↗
PubMed2000

Development and validation of a questionnaire to evaluate patient satisfaction with diabetes disease management.

OBJECTIVE: To develop a reliable and valid questionnaire to measure patient satisfaction with diabetes disease management programs. RESEARCH DESIGN AND METHODS: Questions related to structure, process, and outcomes were categorized into 14 domains defining the essential elements of diabetes disease management. Health professionals confirmed the content validity. Face validity was established by a patient focus group. The questionnaire was mailed to 711 patients with diabetes who participated in a disease management program. To reduce the number of questionnaire items, a principal components analysis was performed using a varimax rotation. The Scree test was used to select significant components. To further assess reliability and validity; Cronbach's alpha and product-moment correlations were calculated for components having > or =3 items with loadings >0.50. RESULTS: The validated 73-item mailed satisfaction survey had a 34.1% response rate. Principal components analysis yielded 13 components with eigenvalues > 1.0. The Scree test proposed a 6-component solution (39 items), which explained 59% of the total variation. Internal consistency reliabilities computed for the first 6 components (alpha = 0.79-0.95) were acceptable. CONCLUSIONS: The final questionnaire, the Diabetes Management Evaluation Tool (DMET), was designed to assess patient satisfaction with diabetes disease management programs. Although more extensive testing of the questionnaire is appropriate, preliminary reliability and validity of the DMET has been demonstrated.

Adolescent↗
PubMed2006

Change in the organization of degrees of freedom with learning.

The authors examined the effects of learning on the change in the organization of the mechanical and dynamical degrees of freedom in 5 men who performed a ski-simulator task. A 3-dimensional analysis of the motion of the total-body center of mass and the segmental centers of mass (head, torso, thighs, and shanks) over practice showed that the recruitment of mechanical degrees of freedom was strongly influenced by anatomical and task constraints. Principal components analysis of the body segments' motions revealed that practice shifted their relative contributions but did not change the number of principal components. The present findings show that there can be independence in the patterns of change in the mechanical and dynamical degrees of freedom that arise from practice.

Adolescent↗
PubMed1999

Statistical method for characterization of hypertrophic cardiomyopathy by use of morphologic and pathologic measurements in pigs (Sus scrofa domestica).

BACKGROUND AND PURPOSE: Hypertrophic cardiomyopathy (HCM) is characterized by symmetric or asymmetric hypertrophy of the left and/or right ventricle. Morphologic and pathologic indices (MI and PI) of hearts were established for classification of HCM in pigs. METHODS: Fifty on-farm-performance-tested pigs (average body weight, 104.3 kg; age, 224.5 days) were randomly selected. Heart weight, length, width, heart-to-body weight ratio, and thickness of the cranial and middle portions of ventricular septum and left ventricular free wall were measured. Myocyte disorganization and necrosis, myocardial and endocardial fibrosis, and intramural coronary arterial occlusion were scored. Principal component analysis and stepwise regression analysis were used to establish MI and PI. RESULTS: MI was established by using the first principal component as the dependent variable and applying stepwise regression analysis. Hearts were classified as morphologically normal, suspicious, and hypertrophic according to the range of MI. The same statistical method was used to find PI. Hearts were classified as pathologically normal, moderately affected, or seriously affected according to the range of PI. Combining MI and PI, hearts could be classified into five groups: no hypertrophy with minor lesion (normal); hypertrophy but with rare lesion; no hypertrophy but seriously affected; suspicious; and hypertrophy and seriously affected (heart with HCM). Another 119 hearts were collected and classified. The variation of heart measurements was consistent with the original purpose of classification. CONCLUSIONS: Using fewer measurements for identification of HCM objectively in pigs seems to have practical application.

Animals↗
PubMed1991

Morphometry and classification of the cat hypothalamic capillaries using multivariate analysis.

Multivariate statistical methods were used to do morphological determination of the amount and the relation of the astrocytic foot processes (AF), astrocytic lamina (AL) and dense zones (DZ) on hypothalamic capillaries. We corroborated that 100% of the perivascular membrane is surrounded by glial astrocytic cytoplasm. Principal component analysis shows that the original variables are independent of one another. Cluster analysis confirms the individual situation obtained through the principal component analysis. Discriminant analysis shows that the discriminant capacity of the 3 variables is very significant. For the potential interrelations of astrocytic foot processes, astrocytic lamina and dense zones we have clearly differentiated four groups of hypothalamic capillaries.

Animals↗
PubMedDate not supplied

Factor analysis of metabolic syndrome among the middle-aged Bengalee Hindu men of Calcutta, India.

BACKGROUND: The prevalence of coronary heart disease (CHD) is known to be very high in the people of Indian origin. In India, rates are rising and CHD has been predicted to rank first among the causes of death in the Indian population by 2015. The reasons for the increased susceptibility of Indians to CHD are yet to be understood completely. However, studies hinted that clustering of risk variables of the metabolic syndrome (MS) could be responsible for the increasing incidence of CHD in the Indians. Therefore, identification of the components of the MS could be one aspect in the way to curb the increasing incidence of CHD among the Asian Indians. METHODS: Principal component factor analysis (PCFA) was undertaken to identify the components or factors of the metabolic syndrome (MS) among the middle-aged Bengalee Hindu men of Calcutta, India, and was compared with the findings from other studies. The present cross-sectional study consisted of 212 Bengalee Hindu men aged 30 years and above. Besides anthropometric measures, lipid profile, blood pressure, and fasting plasma glucose (FPG) were collected from each participant. Waist-hip ratio (WHR), trunk-extremity ratio (TER), and central fat skinfold ratio (CFSR) were computed accordingly. The lipid profile measures that were included were total cholesterol (TC), fasting triglyceride (FTG), high (HDL-C), low (LDL-C), and very low density lipoprotein cholesterol (VLDL-C). RESULTS: Principal components factor analysis revealed four uncorrelated factors that cumulatively explained 72.37% of the observed variance of the metabolic syndrome by measured variables. These four factors could be identified as central obesity (factor 1), centralized subcutaneous fat (factor 2), lipid profile blood glucose (factor 3), and blood pressure (factor 4). The present factor analysis confirms the general finding from other factor analyses of the metabolic syndrome on different ethnic groups that have identified three to four factors. Furthermore, the first two factors, that is, central obesity and centralized subcutaneous fat cumulatively explained 47% of the observed variance of metabolic syndrome in this population. CONCLUSION: Since more than one factor was identified for the metabolic syndrome and as no observed variable loaded on all four factors, therefore, more than one physiological mechanism could be accounted for the clustering of risk variables of the metabolic syndrome among the Bengalee Hindu men.

Adult↗
PubMed2002

Identification of quantitative trait loci controlling developmental characteristics of Brassica oleracea L.

A segregating population of F(1)-derived doubled haploid (DH) lines of Brassica oleracea was used to detect and locate QTLs controlling 27 morphological and developmental traits, including leaf, flowering, axillary bud and stem characters. The population resulted from a cross between two very different B. oleracea crop types, an annual cauliflower and a biennial Brussels sprout. A principal component analysis (PCA), based on line means, allowed all the traits to be grouped into distinct categories according to the first five Principal Components. These were: leaf traits (PC1), flowering traits (PC2), axillary bud traits (PC3 and 5) and stem traits (PC4). Between zero and four putative QTL were located per trait, which individually explained between 6% and 43% of the additive genetic variation, using the multiple-marker regression approach to QTL mapping. For lamina width, bare petiole length and stem length two QTL with opposite effects were detected on the same linkage groups. Intra- and inter-specific comparative mapping using RFLP markers identified a QTL on linkage group O8 accounting for variation in vernalisation, which is probably synonymous with a QTL detected on linkage group N19 of Brassica napus. In addition, a QTL for petiole length detected on O3 of this study appeared to be homologous to a QTL detected on another B. oleracea genetic map (Camargo et al. 1995).

Journal Article↗
PubMed2007

Multivariate data analysis of pollutant profiles: PCB levels across Europe.

It is not always recognised that standard multivariate analyses applied to pollution profile data (i.e. where data are relative amounts of pollutants expressed as proportions of their total) give rise to problems in the analysis and interpretation of results: a simple solution is to carry out analyses on log-ratios of proportions. However, while solving many problems, this approach is very sensitive to the issue of values below detection limits. These approaches have been applied to a dataset of the levels of 29 PCB congeners in ambient air samples across Europe during the summer of 2002. Multivariate descriptive methods (principal component analysis and cluster analysis) and inferential techniques (multivariate ANOVA, multiple linear and logistic regression) and graphical tools (2D and 3D plots, principal components plots, biplots and triangular diagrams) were used to analyse the proportions of five PCB homologues (tri-hepta). These established that there was considerable difference in the pollution profiles of the 71 samples: the greatest variation was between samples with differing ratios of tri-hexa and tri-hepta PCB homologues, and the samples showed little sign of consistent clusters. There was a significant difference between typical profiles from rural and urban areas such that urban samples (and those with high total PCBs) had higher proportions of tetra- and tri-PCBs compared to hexa- and hepta-PCBs.

Analysis of Variance↗
PubMed2006

Metal profiles used as environmental markers of green turtle (Chelonia mydas) foraging resources.

The Baja California Peninsula, Mexico serves an important role for feeding and developing sea turtles. High concentrations of metals detected in green turtles (Chelonia mydas) from Magdalena Bay prompted an investigation into the sources of metals in the region. We compared metal concentrations in sea turtle tissues with plant species found in their stomach contents, and with the same species of plants collected inside a sea turtle refuge area known as Estero Banderitas. Differences in the metal concentrations between marine plant species were minimal. Principal components analysis of the percent contribution of individual metals to the overall metal signature of each plant or tissue sample generated three principal components that explained 80.7% of the total variance in the data. The plant samples collected within Estero Banderitas formed a separate grouping from the green turtle tissue samples and the plants from the stomach contents. The plants in the stomach contents contained greater percent contributions of Cd and Zn than the plants collected inside the bay, while Pb and Mn contributed more to the metal profiles in the bay samples. The metal profiles in the sea turtle tissues more closely resembled the stomach contents than the same species of plants collected within Estero Banderitas, and suggest that sea turtles collected inside Magdalena Bay use foraging resources outside of the Estero Banderitas region. This work supports the suggestion that metal profiles can be used as "environmentally acquired markers" to improve our understanding of the extent of sea turtle foraging areas.

Alismatales↗
PubMed1999

Interpretation of heavy metal data from mussel by use of multivariate classification techniques.

Different strategies of multivariate analysis of metals concentrations (Mn, Fe, Ni, V, Co, Cu, Cd, Hg, Pb, Na, K) in mussel samples from different spanish markets are used to interpret a data base and identify differences between species and origin of the samples. Principal Component Analysis and Potential curves are applied to properly classify unknown samples from representative mussels samples (Mytilus edulis and Perna canaliculus). Also, Principal Components Analysis is used as display method to visualize the relation between the variables and objects of interest.

Animals↗
PubMed2003

Study of air pollutants in Hong Kong using energy dispersive X-ray fluorescence.

Airborne particulate samples were collected from various reference sites in Hong Kong and the energy dispersive X-ray fluorescence (EDXRF) intensities for 19 chemical elements were recorded. Principal component analysis (PCA) was employed so that the variances of these 19 original variables were captured by a few new indices called principal components or PCs. Data points for similar sources were automatically grouped together in a plot of the first three PCs (PC plot). Data for the monitoring site Mong Kok were located within the area defined by vehicular emissions. As such, the main air pollutant at this site was concluded to originate from vehicular emissions. A fraction of data for the Causeway Bay monitoring site also fell into this same identified area, so the main air pollutant could also be vehicular emissions. Some of the data located either on or outside the border can be explained in terms of meteorology.

Air Pollutants↗
PubMed2005

Front-face fluorescence spectroscopy allows the characterization of mild heat treatments applied to milk. Relations with the denaturation of milk proteins.

Emission and excitation spectra of intrinsic fluorophores present in milk were used to evaluate changes in milk following thermal treatments in the 57-72 degrees C temperature range from 0.5 min up to 30 min. Alternatively, the concentrations of native alkaline phosphatase, lactoferrin, immunoglobulin G, bovine serum albumin, beta-lactoglobulin, and alpha-lactalbumin were determined in the same samples by enzymatic and immunochemical techniques. As principal component analysis applied to the normalized fluorescence spectra successfully discriminated different milk samples according to the temperature and time of thermal treatment, principal component regression was applied to predict the amounts of the native proteins investigated using fluorescence data. The results showed strong correlations between measured and predicted data for alkaline phosphatase and beta-lactoglobulin. This study has demonstrated that front-face fluorescence spectroscopy has a promising potential to become a rapid and nondestructive analytical technique for the evaluation of physicochemical changes in milk induced by low thermal treatment.

Alkaline Phosphatase↗
PubMed1991

Febrile convulsions in northern Japan: a quantitative and qualitative analysis of EEG and clinical findings.

In an attempt to describe the characteristics of febrile convulsions (FC) 133 children with a history of FC were checked neurologically at health centers in northern Japan. Using categorical data from principal component analysis, family history of FC, recurrence and body temperature prior to convulsion, EEG disorders, exogenous factors, age at onset as the principal components were extracted. A quantitative and qualitative analysis of EEG showed that children with FC had more paroxysmal and basic abnormalities, that the rate of appearance of theta wave was more common and of alpha wave was less common, and that mean values of frequency ranges of theta and alpha wave ranges together were significantly lower in the background activity than those of control group children.

Cerebral Cortex↗
PubMed2003

Modulation of dorsal spinocerebellar responses to limb movement. I. Effect of serotonin.

Spinocerebellar neurons (DSCT) receive converging sensory information from various sensory receptors in the hindlimbs and lower trunk. Previous studies have shown that sensory processing by DSCT neurons results in a representation of global hindlimb kinematic parameters such as the length and the orientation of the limb axis. In addition to the sensory input, the DSCT circuitry also receives a descending input from the raphe nuclei in the brain stem. Recent studies have demonstrated that the raphe serotonergic terminals synapse directly on DSCT neurons and exert a differential modulatory influence on their sensory inputs. We examined the role of serotonergic modulation on the DSCT representation of hindlimb kinematic parameters by recording DSCT activity during passive hindlimb movements before and after perturbing serotonergic transmission. We used two types of perturbation: electrical stimulation of the raphe areas in the brain stem to release serotonin in the spinal cord (42 neurons) and intravenous administration of serotonergic agonists or antagonists, mostly the 5HTP2 antagonist ketanserin (30 neurons). We found that movement responses were altered in approximately 70% of the DSCT units studied with each protocol. Changes could include shifts in mean firing rate, increases or decreases in response amplitude, and changes in response waveform. We used a principal component analysis (PCA) to examine waveform components and to determine how they contributed to the response waveform changes caused by serotonin perturbation. Such changes could be explained by new or different response components that might indicate a modification in the data processing or by a different weighting of existing components that might indicate a modification of synaptic weighting. The results were consistent with the second alternative. We found that the same underlying response components could account for both control responses and those altered by serotonin perturbations. The observed changes in waveform could be entirely accounted for by a re-weighting of response components. In particular, the changes observed after raphe stimulation could be accounted for by selective changes in the weighting of the first principal component (PC) with only minor changes of the weighting of the second PC. Because these response components were shown previously to correlate with the limb axis orientation and length trajectories respectively, the finding is consistent with the idea that limb axis length and orientation information are processed separately within the spinal circuitry.

Animals↗
PubMed1997

Relationship between body condition scores and milk yield in a large dairy herd of high yielding Holstein cows.

This study investigated the relationship between body condition and milk yield of dairy cows. Holstein cows (n = 779) on a commercial dairy farm were scored for body condition weekly beginning at dry-off and continuing until 120 d of lactation. Multiple linear regression and principal component analysis were used to characterize relationships. Mean body condition scores were 2.77 and 2.66 at dry-off and parturition, respectively. Principal component analysis was used to reduce the collinearity among independent variables, to calculate new parameter estimates, and to rank the relationship of each variable with milk yield. Results indicated that change in body condition during the dry period was ranked first, followed by lactation number, and then body condition score at dry-off for multiparous cows. A one-point increase in body condition score between dry-off and parturition was associated with 545.5 kg more milk in the first 120 d of lactation. Each additional point of body condition at dry-off was associated with 300 kg less milk at 120 d of lactation. Results suggested that cows that gained condition during the dry period yielded more milk in the first 120 d of lactation and had an accelerated rate of increase in milk yield. The results of this study indicate that body condition score is an important tool for monitoring dairy herds.

Adipose Tissue↗
PubMed2002

[Reliability and validition of the Slovak modified version of the Stanford Health Assessment Questionnaire using the functional disability index in patients with rheumatoid arthritis].

BACKGROUND: Functional disability is one of the most important consequences of RA in the patient's daily life. The HAQ has been widely used in its self administered form for the assessment of disability. A sensitive and valid instrument is needed for a Slovak population with RA. OBJECTIVE: To evaluate reliability and validity of the Slovak version of the HAQ in patients with RA and to explore relationships between HAQ score and disease activity and to provide information concerning utilization of this instrument in clinical practice. METHODS: In preparing the Slovak version of the HAQ careful attention has been paid to the translation, in terms of linguistic and conceptual equivalence, in order to preserve the original purpose of the instrument. The wording of some items required adaptation to the current activities of daily living and Slovak lifestyle. The sample consisted of 160 RA-patients, out of which 135 were women and 25 were men. The inclusion criteria were the following: age from 20 to 70 years at the onset of the study, diagnosis of RA according to the ARA criteria. The exclusion criteria were the presence of another serious disease or very disabling RA (stage IV of the Steinbrocker's classification). To analyze the data t-test, correlations, one-way analysis of variance (ANOVA), and principal component analysis (PCA) available in the SPSS/PC+ statistical package were used. RESULTS: The Cronbach's coefficient of reliability alpha for the HAQ total scale was 0.94. The results of PCA showed that the 20 HAQ items loaded on four components for which the eigen values were greater than 1, accounting for 70% of overall interpersonal variability. Orthogonal varimax rotation of the principal components provided factor loadings reflecting the eight dimensions within the HAQ. Validity of the HAQ was examined further by means of known-groups technique. The HAQ was found to be sensitive to differentiate between the Steinbrocker's functional capacity groups, as well as between males and females. Moreover, significant correlations (p < or = 0.01) were found between the HAQ and the C-reactive protein, the ESR, the NHP-pain, the Ritchie articular index, the Steinbrocker's functional capacity (r = 0.31-0.62) and disease duration (p < or = 0.05, r = 0.17). CONCLUSION: The results of the current investigation provide support for reliability and construct validity of the Slovak version of the HAQ in patients with RA. The HAQ has sufficient discriminant ability. The index disability can be used as an criterion of severity of RA, as a criterion of effectiveness in therapeutical trials for patient stratification of the Slovak population with RA.

Activities of Daily Living↗