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PubMed1991

A multivariate analysis of cardiac growth in human embryos: endocardial cushions and ventricular myocardium.

STUDY OBJECTIVE: In view of the controversy about the morphological significance of the endocardial cushion tissue and ventricular myocardium during cardiac development, the aim was to carry out quantitative studies of these structures. DESIGN: Endocardial cushion tissue and ventricular myocardium were quantified by point count planimetry. The relative growth of the volume of these structures, and also the embryonic crown-rump length, was studied by multivariate allometry (principal components analysis) with the covariance matrix calculated from natural logarithms of the data. EXPERIMENTAL MATERIAL: 27 serially sectioned human embryos were studied, ranging from stage 15 to stage 23 (Paris collection). MEASUREMENTS AND MAIN RESULTS: The relative growth of endocardial cushion tissue, ventricular myocardium, and crown-rump length was discontinuous during the postsomitic period. The first component in principal components analysis measures overall size and, in the present analysis, accounts for 88.6% of the total variance. The growth vector isometry hypothesis was checked with the chi 2 test. This showed that differences in growth between cardiac structures and crown-rump length were allometric (p less than 0.01). Endocardial cushion tissue volume and crown-rump length grew with negative allometry during the second month of gestation, while ventricular myocardium volume grew with positive allometry. CONCLUSIONS: The results agree with those researchers who consider that endocardial cushion tissue functions only in causing initial cardiac fusion and partitioning, with little influence on the formation of definitive cardiac structures.

Heart↗
PubMed2001

Birth as a multidimensional experience: comparison of the English- and German-language versions of Salmon's Item List.

Results concerning satisfaction with the birth experience in different trials are difficult to compare, owing to a lack of internationally used research scales. Salmon's Item List (SIL) is easy-to-handle and would therefore be very helpful for research as well as for obstetric clinic quality control. Two hundred and fifty-one patients were investigated using a German-language version of SIL (SIL-ger); the statistical evaluation was carried out by means of a principal components analysis. Principal components analysis revealed two major findings: (1) as stated by other authors the birth experience is multidimensional, each aspect influencing the others in a non-linear way; (2) in addition to Salmon's dimensions (i.e. postnatal 'fulfillment', intranatal 'physical discomfort' and intranatal 'emotional distress') another postnatal dimension labeled 'negative emotional experience' was detected. Not only are intranatal experiences multidimensional, but so too are evaluative feelings afterwards. In addition to fulfillment, as developed by Salmon, a dimension of negative emotional experience needs to be taken into account. This dimension does not correlate in a linear way with fulfillment. It is appropriate to use SIL in research. Before using it for purposes of clinical quality control, however, larger samples need to be evaluated in order to prove the stability of the factor structure.

Cross-Cultural Comparison↗
PubMed2000

[Relation among early maturation, body mass index and the longitudinal behavior of systolic blood pressure].

In the Caracas Longitudinal Study, 53 girls- 8 to 11 years of age- who had been classified as early, average and late maturers were analyzed longitudinally with respect to Body Mass Index (BMI) and Systolic Blood Pressure (SBP). A longitudinal principal component analysis was used to summarize trends or intraindividual changes in BMI and SBP. A first component was identified for BMI, this component accounted for most of its total variance (94.65%). Girls were classified as normal in weight or at risk of overweight on the basis of this component. Three principal components were identified for SBP, that accounted for 91.83% of the total variance of this variable. The first component represented a measure of position across the whole age period, a "canalization pattern"; this component accounted for most of the total variance (45.65%). The second component revealed an unidirectional change in relative position of the values of the variable, a "decanalization pattern", and a third pattern summarized deviations around a position level: "recanalization pattern". Girls who showed a canalization pattern for SBP were those identified as early maturers and at risk of overweight.

Blood Pressure↗
PubMed2002

Significance of nocturia in the International Prostate Symptom Score for benign prostatic hyperplasia.

PURPOSE: We studied the relationship of nocturia with the International Prostate Symptom Score in men with lower urinary tract symptoms due to benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: Baseline symptom score and the change in the score by treatment were analyzed in 219 consecutive Japanese men with BPH using basic statistics, and correlation, cluster and principal component analyses. RESULTS: The average nocturia score was the middle of that of the 7 symptoms at baseline and by far the highest after treatment. Hence, the score change was the smallest. Analysis of baseline scores demonstrated that all symptoms were the initial component in principal component analysis with individual symptom scores correlating with the total symptom score and quality of life index. However, the correlation was least for nocturia. Observations were similar when analyzing the score change by treatment. These results indicate that the nocturia score is least specific to symptoms associated with BPH or least sensitive to the therapeutic effect on symptoms. This finding may be related to the high nocturia score in the age matched control population. CONCLUSIONS: The nocturia score of the International Prostate Symptom Score behaves differently in the symptom complex of BPH in Japanese men, partially because it is most confounded by the aging factor.

Aged↗
PubMed2004

Principal geodesic analysis for the study of nonlinear statistics of shape.

A primary goal of statistical shape analysis is to describe the variability of a population of geometric objects. A standard technique for computing such descriptions is principal component analysis. However, principal component analysis is limited in that it only works for data lying in a Euclidean vector space. While this is certainly sufficient for geometric models that are parameterized by a set of landmarks or a dense collection of boundary points, it does not handle more complex representations of shape. We have been developing representations of geometry based on the medial axis description or m-rep. While the medial representation provides a rich language for variability in terms of bending, twisting, and widening, the medial parameters are not elements of a Euclidean vector space. They are in fact elements of a nonlinear Riemannian symmetric space. In this paper, we develop the method of principal geodesic analysis, a generalization of principal component analysis to the manifold setting. We demonstrate its use in describing the variability of medially-defined anatomical objects. Results of applying this framework on a population of hippocampi in a schizophrenia study are presented.

Algorithms↗
PubMedDate not supplied

Genetic algorithm applied to the selection of factors in principal component-artificial neural networks: application to QSAR study of calcium channel antagonist activity of 1,4-dihydropyridines (nifedipine analogous).

A QSAR algorithm, principal component-genetic algorithm-artificial neural network (PC-GA-ANN), has been applied to a set of newly synthesized calcium channel blockers, which are of special interest because of their role in cardiac diseases. A data set of 124 1,4-dihydropyridines bearing different ester substituents at the C-3 and C-5 positions of the dihydropyridine ring and nitroimidazolyl, phenylimidazolyl, and methylsulfonylimidazolyl groups at the C-4 position with known Ca(2+) channel binding affinities was employed in this study. Ten different sets of descriptors (837 descriptors) were calculated for each molecule. The principal component analysis was used to compress the descriptor groups into principal components. The most significant descriptors of each set were selected and used as input for the ANN. The genetic algorithm (GA) was used for the selection of the best set of extracted principal components. A feed forward artificial neural network with a back-propagation of error algorithm was used to process the nonlinear relationship between the selected principal components and biological activity of the dihydropyridines. A comparison between PC-GA-ANN and routine PC-ANN shows that the first model yields better prediction ability.

Algorithms↗
PubMed2006

High dynamic range image rendering with a Retinex-based adaptive filter.

We propose a new method to render high dynamic range images that models global and local adaptation of the human visual system. Our method is based on the center-surround Retinex model. The novelties of our method is first to use an adaptive filter, whose shape follows the image high-contrast edges, thus reducing halo artifacts common to other methods. Second, only the luminance channel is processed, which is defined by the first component of a principal component analysis. Principal component analysis provides orthogonality between channels and thus reduces the chromatic changes caused by the modification of luminance. We show that our method efficiently renders high dynamic range images and we compare our results with the current state of the art.

Algorithms↗
PubMed1975

Study of an intravenous fat tolerance test with Intralipid. II. The relation between K2 and PHLA with special reference to clinical data in human subjects.

The relation between K2 and PHLA was studied in human subjects with special reference to clinical data determined by routine laboratory and physical examinations. The results obtained by Multiple Regression Analysis indicated that those factors which may contribute to K2 variation were fasting triglyceride level and age. There was an inverse partial correlation between K2 and fasting triglyceride level and between K2 and age. The first and second principal components calculated by Principal Component Analysis indicated that K2 is closely related to obesity and hyperlipidemia, especially hypertriglyceridemia, while PHLA related to albumin. These two components also suggested that K2 fibes different clinical information from that obtained by PHLA measurement. There was no partial correlation between K2 and PHLA. The various lipoprotein paper electrophoretic patterns, type IIa, type IIb, type IV and normal patterns, were clearly characterized by such factors as K2, plasma triglyceride and degree of obesity which has high coefficients in the first principal component.

Adult↗
PubMed1986

Calfhood weights, body measurements and measures of fatness versus criteria of overall size and shape for predicting yearling performance in beef cattle.

Data were collected over a period of 4 yr from bulls and heifers of two location-breed groups (East Tennessee-Polled Hereford, Cumberland Plateau-Angus). Variables measured and recorded at the time all calves were weaned (at an average age of approximately 230 d) were age (in d at time of data collection; AGE), weight (WT), visual condition score (COND), ultrasonically measured subcutaneous fat thickness (FAT), body length (LT), heart girth (HG) and hip width (HIP). These variables were included in principal-components (PC) analyses. The first principal component (PC1) was a measure of overall size, accounting for 66 to 69% of the total variation. Remaining principal components contrasted body shapes. Stepwise multiple regression analyses (separate for each location-sex subgroup) were conducted using various combinations of the weaning variables listed above, or principal components of these variables, to predict birth to yearling average daily gain (BYADG), weaning to yearling average daily gain (WYADG) and yearling condition score (YCOND). Condition score (COND) appeared to be the most valuable complement to AGE and WT, with LT somewhat useful also. In equations including principal components, after AGE, PC1 most frequently entered first, generally followed by PC2. Coefficients of multiple determination (R2) were largest for BYADG (greater than .50), followed by YCOND (.15 to .50) and WYADG (less than .15). Longer-bodied, thinner-fleshed animals of a given age and weight tended to have larger gains and smaller YCOND.

Adipose Tissue↗
PubMed2006

The scent of urine spots of male mice, Mus musculus: Changes in chemical composition over time.

A dominant male mouse scent-marks his territory very frequently by emitting small urinary spots. The urine spots release in the air a variety of odorants that transmit different information to other mice, especially those concerning the time of deposition. To investigate this effect, small spots of urine of a dominant male mouse were left to freely release the odorants in the air for time intervals ranging from 0 min to 24 h prior to sampling. Thereupon, the odorants remaining in the spot were sampled at diffusion equilibrium (45 degrees C) in a small vial by means of headspace solid-phase microextraction followed by gas chromatography coupled to flame ionisation detection and mass spectrometry. Thirteen odorants were consistently found. Nine odorants were identified and four were matched. The rate of release of each odorant was characteristic and was described using principal component analysis. A first principal component was based on nine early odorants that showed a decreasing release over time. The odorants were 2,4-dehydro-exo-brevicomin, an unknown with 78% matching to 4-acetonilcycloheptanone, linalool, 2,4-dimethyl-phenol, 4-ethylphenol, indole, 2-butyl-1-octanol, an unknown with 83% matching to 2-ethyl-1-decanol, and 2,4-bis-(1,1-dimethylethyl)phenol. A second principal component, based on two unknowns with 73% matching to yohimban-17-one and 71% matching to the 2-methyl-3-hydroxy-2,4,4-trimethyl ester of propanoic acid, had an irregular release after deposition. A third principal component of late odorants, based on 2-sec-butyl-4,5-dihydrothiazole and 6,10-dimethyl-5,9-undecaden-2-one, had a peak of release at about 22 min. In conclusion, the release of the odorants in the headspace of a urine spot may code and transmit information on the deposition time.

Animals↗
PubMed2006

Principal component-based radiative transfer model for hyperspectral sensors: theoretical concept.

Modern infrared satellite sensors such as the Atmospheric Infrared Sounder (AIRS), the Cross-Track Infrared Sounder (CrIS), the Tropospheric Emission Spectrometer (TES), the Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS), and the Infrared Atmospheric Sounding Interferometer (IASI) are capable of providing high spatial and spectral resolution infrared spectra. To fully exploit the vast amount of spectral information from these instruments, superfast radiative transfer models are needed. We present a novel radiative transfer model based on principal component analysis. Instead of predicting channel radiance or transmittance spectra directly, the principal component-based radiative transfer model (PCRTM) predicts the principal component (PC) scores of these quantities. This prediction ability leads to significant savings in computational time. The parameterization of the PCRTM model is derived from the properties of PC scores and instrument line-shape functions. The PCRTM is accurate and flexible. Because of its high speed and compressed spectral information format, it has great potential for superfast one-dimensional physical retrieval and for numerical weather prediction large volume radiance data assimilation applications. The model has been successfully developed for the NAST-I and AIRS instruments. The PCRTM model performs monochromatic radiative transfer calculations and is able to include multiple scattering calculations to account for clouds and aerosols.

Journal Article↗
PubMed2006

Strategies for reducing large fMRI data sets for independent component analysis.

In independent component analysis (ICA), principal component analysis (PCA) is generally used to reduce the raw data to a few principal components (PCs) through eigenvector decomposition (EVD) on the data covariance matrix. Although this works for spatial ICA (sICA) on moderately sized fMRI data, it is intractable for temporal ICA (tICA), since typical fMRI data have a high spatial dimension, resulting in an unmanageable data covariance matrix. To solve this problem, two practical data reduction methods are presented in this paper. The first solution is to calculate the PCs of tICA from the PCs of sICA. This approach works well for moderately sized fMRI data; however, it is highly computationally intensive, even intractable, when the number of scans increases. The second solution proposed is to perform PCA decomposition via a cascade recursive least squared (CRLS) network, which provides a uniform data reduction solution for both sICA and tICA. Without the need to calculate the covariance matrix, CRLS extracts PCs directly from the raw data, and the PC extraction can be terminated after computing an arbitrary number of PCs without the need to estimate the whole set of PCs. Moreover, when the whole data set becomes too large to be loaded into the machine memory, CRLS-PCA can save data retrieval time by reading the data once, while the conventional PCA requires numerous data retrieval steps for both covariance matrix calculation and PC extractions. Real fMRI data were used to evaluate the PC extraction precision, computational expense, and memory usage of the presented methods.

Algorithms↗
PubMed1987

Temporal encoding of two-dimensional patterns by single units in primate inferior temporal cortex. III. Information theoretic analysis.

Ablation and single-unit studies in primates have shown that inferior temporal (IT) cortex is important for pattern discrimination. The first paper in this series suggested that single units in IT cortex of alert monkeys respond to a set of two-dimensional patterns with complex temporal modulation of their spike trains. The second paper quantified the waveform of the modulated responses of IT neurons with principal components and demonstrated that the coefficients of two to four of the principal components were stimulus dependent. Although the coefficients of the principal components are uncorrelated, it is possible that they are not statistically independent. That is, several coefficients could be determined by the same feature of the stimulus, and thus could be conveying the same information. The final part of this study examined this issue by comparing the amount of information about the stimulus that can be conveyed by two codes: a temporal waveform code derived from the coefficients of the first three principal components and a mean rate code derived from the spike count. We considered the neuron to be an information channel conveying messages about stimulus parameters. Previous applications of information theory to neurophysiology have dealt either with the theoretical capacity of neuronal channels or the temporal distribution of information within the spike train. This previous work usually used a general binary code to represent the spike train of a neuron's response. Such a general approach yields no indication of the nature of the neuron's intrinsic coding scheme because it depends only on the timing of spikes in the response. In particular, it is independent of any statistical properties of the responses. Our approach uses the principal components of the response waveform to derive a code for representing information about the stimuli. We regard this code as an indication of the neuron's intrinsic coding scheme, because it is based on the statistical properties of the neuronal responses. We measured how much information about the stimulus was present in the neuron's responses. This transmitted information was calculated for codes based on either the spike count or on the first three principal components of the response waveform. The information transmitted by each of the first three principal components was largely independent of that transmitted by the others. It was found that the average amount of information transmitted by the principal components was about twice as large as that transmitted by the spike count.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2006

Multivariate statistical analysis of metal concentrations in teeth of residents of Silesian region, southern Poland.

Concentrations of 11 metals (Cd, Cr, Cu, Fe, Mn, Pb, Zn, Na, K, Ca, and Mg) were assayed in the teeth of two populations of the Silesian region. The first group (n = 83) comprised the residents of Katowice-Szopienice, a town located in the center of the Upper Silesian industrial region, in close proximity to a Pb plant, whereas the other was a group of residents of the agricultural community Strumień (n = 44). The concentrations of all the trace metals were found to be higher in the teeth of Katowice-Szopienice residents. The methods of cluster analysis distinguished two clusters of metals in the teeth: essential (Ca, Na, Mg, Zn, and K) and trace (Cd, Mn, Cr, Cu, Fe, and Pb) elements. Euclidean distances reflected the differences in concentrations between the two groups. The results obtained were analyzed using principal component analysis. Four principal factors accounted for 68.1% of the total variance for Katowice-Szopienice residents and for 80.1% for Strumień residents. The first factor showed high contributions of Cu and Cr, elements present in humans as a result of diet, and also Mn for Katowice-Szopienice residents because of environmental contamination. The second factor was characterized by large Zn and Cd fractions and, for Katowice-Szopienice residents, Pb and K as well. The diversified exposure of both populations was reflected by the differences in Euclidean distances and contribution of particular elements with respect of principal components.

Adolescent↗
PubMed1991

Lateral geniculate neurons in behaving primates. II. Encoding of visual information in the temporal shape of the response.

1. We used the Karhunen-Loève (K-L) transform to quantify the temporal distribution of spikes in the responses of lateral geniculate (LGN) neurons. The basis functions of the K-L transform are a set of waveforms called principal components, which are extracted from the data set. The coefficients of the principal components are uncorrelated with each other and can be used to quantify individual responses. The shapes of each of the first three principal components were very similar across neurons. 2. The coefficient of the first principal component was highly correlated with the spike count, but the other coefficients were not. Thus the coefficient of the first principal component reflects the strength of the response, whereas the coefficients of the other principal components reflect aspects of the temporal distribution of spikes in the response that are uncorrelated with the strength of the response. Statistical analysis revealed that the coefficients of up to 10 principal components were driven by the stimuli. Therefore stimuli govern the temporal distribution as well as the number of spikes in the response. 3. Through the application of information theory, we were able to compare the amount of stimulus-related information carried by LGN neurons when two codes were assumed: first, a univariate code based on response strength alone; and second, a multivariate temporal code based on the coefficients of the first three principal components. We found that LGN neurons were able to transmit an average of 1.5 times as much information using the three-component temporal code as they could using the strength code. 4. The stimulus set we used allowed us to calculate the amount of information each neuron could transmit about stimulus luminance, pattern, and contrast. All neurons transmitted the greatest amount of information about stimulus luminance, but they also transmitted significant amounts of information about stimulus pattern. This pattern information was not a reflection of the luminance or contrast of the pixel centered on the receptive field. 5. In addition to measuring the average amount of information each neuron transmitted about all stimuli, we also measured the amount of information each neuron transmitted about the individual stimuli with both the univariate spike count code and the multivariate temporal code. We then compared the amount of information transmitted per stimulus with the magnitudes of the responses to the individual stimuli. We found that the magnitudes of both the univariate and the multivariate responses to individual stimuli were poorly correlated with the information transmitted about the individual stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2004

Lineage specificity of gene expression patterns.

The hematopoietic system offers many advantages as a model for understanding general aspects of lineage choice and specification. Using oligonucleotide microarrays, we compared gene expression patterns of multiple purified hematopoietic cell populations, including neutrophils, monocytes, macrophages, resting, centrocytic, and centroblastic B lymphocytes, dendritic cells, and hematopoietic stem cells. Some of these cells were studied under both resting and stimulated conditions. We studied the collective behavior of subsets of genes derived from the Biocarta database of functional pathways, hand-tuned groupings of genes into broad functional categories based on the Gene Ontology database, and the metabolic pathways in the Kyoto Encyclopedia of Genes and Genomes database. Principal component analysis revealed strikingly pervasive differences in relative levels of gene expression among cell lineages that involve most of the subsets examined. These results indicate that many processes in these cells behave differently in different lineages. Much of the variation among lineages was captured by the first few principal components. Principal components biplots were found to provide a convenient visual display of the contributions of the various genes within the subsets in lineage discrimination. Moreover, by applying tree-constructing methodologies borrowed from phylogenetics to the expression data from differentiated cells and stem cells, we reconstructed a tree of relationships that resembled the established hematopoietic program of lineage development. Thus, the mRNA expression data implicitly contained information about developmental relationships among cell types.

Cell Lineage↗
PubMed2005

Modulation of behavior and cortical motor activity in healthy subjects by a chronic administration of a serotonin enhancer.

UNLABELLED: SSRIs are postulated to modulate motor behavior. A single dose of selective serotoninergic reuptake inhibitors (SSRIs) like fluoxetine, paroxetine, or fluvoxamine, has been shown to improve motor performance and efficiency of information processing for simple sensorimotor tasks in healthy subjects. At a cortical level, a single dose of SSRI was shown to induce a hyperactivation of the primary sensorimotor cortex (S1M1) involved in the movement (Loubinoux, I., Boulanouar, K., Ranjeva, J. P., Carel, C., Berry, I., Rascol, O., Celsis, P., and Chollet, F., 1999. Cerebral functional magnetic resonance imaging activation modulated by a single dose of the monoamine neurotransmission enhancers fluoxetine and fenozolone during hand sensorimotor tasks. J. Cereb. Blood Flow Metab. 19 1365--1375, Loubinoux, I., Pariente, J., Boulanouar, K., Carel, C., Manelfe, C., Rascol, O., Celsis, P., and Chollet, F., 2002. A Single Dose of Serotonin Neurotransmission Agonist Paroxetine Enhances Motor Output. A double-blind, placebo-controlled, fMRI study in healthy subjects. NeuroImage 15 26--36). Since SSRIs are usually given for several weeks, we assessed the behavioral and cerebral effects of a one-month chronic administration of paroxetine on a larger group. In a double-blind, placebo controlled and crossover study, 19 subjects received daily 20 mg paroxetine or placebo, respectively, over a period of 30 days separated by a wash-out period of 3 months. After each period, the subjects underwent an fMRI (active or passive movement, dexterity task, sensory discrimination task) and a behavioral evaluation. Concurrently, a TMS (transcranial magnetic stimulation) study was conducted (Gerdelat-Mas, A., Loubinoux, I., Tombari, D., Rascol, O., Chollet, F., Simonetta-Moreau, M., 2005. Chronic administration of selective serotonin re-uptake inhibitor (SSRI) paroxetine modulates human motor cortex excitability in healthy subjects. NeuroImage 27,314--322). RESULTS: On the one hand, paroxetine improved motor performances at the finger tapping test (P=0.02) without affecting choice reaction time, strength and dexterity significantly. Subjects were also faster in processing the spatial incongruency between a stimulus and the motor response (P=0.04). In order to differentiate behavioral components, a principal component analysis was performed on all motor tests, and several characteristics were differentiated: strength, speed, skill, attention, and motor response coding. Paroxetine would improve the efficiency of motor response coding (MANOVA on the factors; factor 3, P=0.01). On the other hand, the chronic administration induced a significant hypoactivation of S1M1 whatever the task: motor or sensory, simple or complex (random effect analysis, P<0.05). The hypoactivation correlated with the improvement of performances at the finger tapping test (P<0.05) suggesting more efficiency in cerebral motor processing. CONCLUSIONS: Our results showed a clear modulation of sensory and motor cerebral activation after a chronic paroxetine administration. An improvement in both behavior and cerebral efficiency was suggested. It could be hypothesized that monoamines, by an unspecific effect, may tune the response of pyramidal neurons to optimize performances.

Adult↗
PubMedDate not supplied

Gradients of HLA diversity in South American Indians.

Information concerning the HLA-A and -B loci was considered in relation to 3796 Amerindians living in 39 places in South America, data related to HLA-C being based on a smaller subset of 2989 persons distributed among 33 localities. Synthetic gene frequency maps were then constructed using principal-components analysis. Clearly significant longitudinal (principal component 1) and latitudinal (principal components 1, 2, and 3) clines were observed, most probably indicating ancient migration routes.

Alleles↗