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Results for “Dimensionality Reduction”

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PubMed1977

[Reverberation of the hindlimb rudimentation on its innervation in squamate reptiles].

When the dimensional reduction of the hind limb begins, a first caudal displacement of the lombar part of the lombo-sacral plexus - which involves the loss of the first root of the sacral part -- appears with a threshold in the increase in the number of presacral vertebrae. This a first indication of the serpentiform tendancy. Others thresholds can conduct to produce the disappearance of the sacral vertebrae and sacral root. The qualitative reduction only concerns the terminal branches of the plexus and does not seem to be associated with the vertebral elongation. If a caudo-proximal reduction of the brachial plexus occurs early in the lepidosaurian line and exists in all the Squamata, even in the Iguana which have well developed limbs, it is not the same for the reduction of the lombo-sacral plexus which does not appear in these Iguana. At last, if the reduction modalities of the both plexus are often differents, their supposed displacements facilitate the extension of the intermediate vertebral region.

Animals↗

PubMed1981

Numerical evaluation of cytologic data. VIII. Computation of the principal components.

The principal components transformation offers an effective methods for dimensionality reduction and for the assessment of the mutual dependence of observed variables in a data set. An iterative procedure, the so-called power method, for finding a multivariate distribution's eigenvectors and eigenvalues is demonstrated. The projection of feature vectors onto the principal components is shown.

Cell Nucleus↗

PubMed1990

Three-dimensional analysis of infarct size reduction after administration of gallopamil in dogs.

Several interventions have been shown to protect the ischemic myocardium from evolving to necrosis. However, three-dimensional evaluation of infarct size reduction using anatomical measurements is lacking. Therefore, Tc-99m labeled albumin microspheres were injected into the left atrium of 16 dogs, 1 min after coronary artery occlusion, to assess the hypoperfused zone. After 15 min, 8 dogs received, intravenously, gallopamil (Procorum) (Ga: 0.08 mg/k as a bolus + 0.2 mg/k/h for 6 h) and the remaining 8 dogs served as controls. At sacrifice (6 h), the left ventricle was cut into 3 mm slices, stained with triphenyltetrazolium chloride to delineate the size of infarction and autoradiographed to delineate the hypoperfused zone. Lateral reduction was calculated by the difference distance between hypoperfused zone and infarct size on the endocardium, mid-myocardium and epicardium; radial reduction was calculated by the difference of the transmural distance taken at mid-infarction and mid-hypoperfusion and the longitudinal reduction was calculated by the distance of the hypoperfused slices that did not infarct. With this technique it could be demonstrated that gallopamil reduced the size of infarction in all three dimensions.

Animals↗

PubMed1981

Double-label reductive methylation of tissue proteins for precision two-dimensional polyacrylamide-gel electrophoretic analysis.

Reductive methylation has been used to radioactively label crude-extract proteins with 3H or 14C. The procedure achieved good isotope incorporation and resolution of proteins on two-dimensional polyacrylamide gels. It allows high-precision comparison of tissue samples by double-labelling and should facilitate the study of tissue proteins by two-dimensional gel electrophoresis.

Animals↗

PubMed1987

Lipid fluidity and membrane protein dynamics.

Membrane fluidity plays an important role in cellular functions. Membrane proteins are mobile in the lipid fluid environment; lateral diffusion of membrane proteins is slower than expected by theory, due to both the effect of protein crowding in the membrane and to constraints from the aqueous matrix. A major aspect of diffusion is in macromolecular associations: reduction of dimensionality for membrane diffusion facilitates collisional encounters, as those concerned with receptor-mediated signal transduction and with electron transfer chains. In mitochondrial electron transfer, diffusional control is prevented by the excess of collisional encounters between fast-diffusing ubiquinone and the respiratory complexes. Another aspect of dynamics of membrane proteins is their conformational flexibility. Lipids may induce the optimal conformation for catalytic activity. Breaks in Arrhenius plots of membrane-bound enzymes may be related to lipid fluidity: the break could occur when a limiting viscosity is reached for catalytic activity. Viscosity can affect protein conformational changes by inhibiting thermal fluctuations to the inner core of the protein molecule.

Diffusion↗

PubMedDate not supplied

Elemental classification in multi-detector stem images using image analysis clustering techniques.

The multi-detector STEM images form a multi-dimensional measurement space where picture elements of morphologically distinct regions cluster and can be separated for classification using image processing clustering techniques. These images are highly correlated and improve the classification only at the high cost of adding dimensionality. Data reduction techniques which take the class separation into account can be used to compress the useful information carried by these images into a few components to which clustering techniques can be successfully applied. At high magnification, a slight displacement is sometimes observed, which can slightly impair the classification result. The redundancy of the information in the quadrant images suggests their use for phase retrieval - which, added to an energy loss data channel, may greatly improve the classification.

Animals↗

PubMed1988

Stimulus equalization: temporary reduction of stimulus complexity to facilitate discrimination learning.

Learners with limited behavioral repertoires often have difficulty discriminating complex, multidimensional stimuli. Procedures that use gradual stimulus change have been developed to facilitate such discrimination, but these procedures are often difficult to implement and costly in terms of teacher time and expertise. This study investigated the effectiveness of stimulus equalization, an error reduction procedure involving an abrupt but temporary reduction of dimensional complexity. A microcomputer was used for stimulus presentation, data collection, and response analyses. Preschool children's responding to groups of four stimuli differing along several dimensions was analyzed on four discrimination tasks under several conditions. On each task, one element from a different dimension was programmed as correct. When trial-and-error training failed to establish the discrimination, equalization training began in which differences in the irrelevant dimensions were eliminated. When correct responding developed, the differences were reinstated, and correct performance was maintained in all but one instance. In a repeated acquisition design, stimulus equalization was found to be generally effective and superior to the trial-and-error method. Implications for computer-assisted instruction are discussed.

Attention↗

PubMed1994

Phosphorylation reverses the membrane association of peptides that correspond to the basic domains of MARCKS and neuromodulin.

Several groups have observed that phosphorylation causes the MARCKS (Myristoylated Alanine-Rich C Kinase Substrate) protein to move off cell membranes and phospholipid vesicles. Our working hypothesis is that significant membrane binding of MARCKS requires both hydrophobic insertion of the N-terminal myristate into the bilayer and electrostatic association of the single cluster of basic residues in the protein with acidic lipids and that phosphorylation reverses this electrostatic association. Membrane binding measurements with myristoylated peptides and phospholipid vesicles show this hydrophobic moiety could, at best, barely attach proteins to plasma membranes. We report here membrane binding measurements with basic peptides that correspond to the phosphorylation domains of MARCKS and neuromodulin. Binding of these peptides increases sigmoidally with the percent acidic lipid in the phospholipid vesicle and can be described by a Gouy-Chapman/mass action theory that explains how electrostatics and reduction of dimensionality produce apparent cooperativity. The electrostatic affinity of the MARCKS peptide for membranes containing 10% acidic phospholipids (10(4) M-1 = chi/[P], where chi is the mole ratio of peptide bound to the outer monolayer of the vesicles and [P] is the concentration of peptide in the aqueous phase) is the same as the hydrophobic affinity of the myristate moiety for bilayer membranes. Phosphorylation decreases the affinity of the MARCKS peptide for membranes containing 15% acidic lipid about 1000-fold and produces a rapid (t1/2 < 30 s) dissociation of the peptide from phospholipid vesicles.

Amino Acid Sequence↗

PubMed1992

Binding of basic peptides to acidic lipids in membranes: effects of inserting alanine(s) between the basic residues.

We studied the binding of peptides containing five basic residues to membranes containing acidic lipids. The peptides have five arginine or lysine residues and zero, one, or two alanines between the basic groups. The vesicles were formed from mixtures of a zwitterionic lipid, phosphatidylcholine, and an acidic lipid, either phosphatidylserine or phosphatidylglycerol. Measuring the binding using equilibrium dialysis, ultrafiltration, and electrophoretic mobility techniques, we found that all peptides bind to the membranes with a sigmoidal dependence on the mole fraction of acidic lipid. The sigmoidal dependence (Hill coefficient greater than 1 or apparent cooperativity) is due to both electrostatics and reduction of dimensionality and can be described by a simple model that combines Gouy-Chapman-Stern theory with mass action formalism. The adjustable parameter in this model is the microscopic association constant k between a basic residue and an acidic lipid (1 less than k less than 10 M-1). The addition of alanine residues decreases the affinity of the peptides for the membranes; two alanines inserted between the basic residues reduces k 2-fold. Equivalently, the affinity of the peptide for the membrane decreases 10-fold, probably due to a combination of local electrostatic effects and the increased loss of entropy that may occur when the more massive alanine-containing peptides bind to the membrane. The arginine peptides bind more strongly than the lysine peptides: k for an arginine residue is 2-fold higher than for a lysine residue. Our results imply that a cluster of arginine and lysine residues with interspersed electrically neutral amino acids can bind a significant fraction of a cytoplasmic protein to the plasma membrane if the cluster contains more than five basic residues.

Alanine↗

PubMed1988

Brownian dynamics of cytochrome c and cytochrome c peroxidase association.

Brownian dynamics computer simulations of the diffusional association of electron transport proteins cytochrome c (cyt c) and cytochrome c peroxidase (cyt c per) were performed. A highly detailed and realistic model of the protein structures and their electrostatic interactions was used that was based on an atomic-level spatial description. Several structural features played a role in enhancing and optimizing the electron transfer efficiency of this reaction. Favorable electrostatic interactions facilitated long-lived nonspecific encounters between the proteins that allowed the severe orientational criteria for reaction to be overcome by rotational diffusion during encounters. Thus a "reduction-in-dimensionality" effect operated. The proteins achieved plausible electron transfer orientations in a multitude of electrostatically stable encounter complexes, rather than in a single dominant complex.

Chemical Phenomena↗

PubMed1985

Two-dimensional echocardiographic image texture analysis: reduction of regional variability using polar coordinates.

Factors inherent to the ultrasound imaging system can influence quantitative ultrasound image texture and may produce changes that mask or mimic those due to alterations in tissue structure. In this study, we assessed the effect of the method of image data acquisition and analysis on the variations in quantitative texture measures that occurred solely due to the position of a region of interest (ROI) within the field of view. When ROI's, which varied in range and azimuth within the image of a tissue equivalent phantom (of uniform composition), were assessed by conventional analysis of scan-converted (rectangular coordinate) data, over 50 percent of all texture measures showed significant differences. Pseudo polar analysis reduced the number of texture measures showing regional variation by 80 percent (p less than 0.01) and true polar coordinate data analysis reduced the number by 74 percent (p less than 0.01). True polar analysis completely abolished differences in texture measures between ROI's separated in azimuth. Acquisition and analysis of tissue texture data using polar coordinates should allow a more definitive identification of abnormal tissue.

Echocardiography↗

PubMed1984

Mandible analysis of NOD and NON strains of mice.

10 inbred strains of mice including NOD and NON were identified by discriminant and canonical discriminant analysis of the mandible measurements. The number of erroneous discriminations was 0.5% (1/199) for the females and 0% for males (0/232). In canonical discriminant analysis (discriminant analysis with reduction of dimensionality), NOD and NON inbred strains were separately located on 2-dimensional planes, Z1-Z2, Z1-Z3, and Z2-Z3. These results clearly indicate that the genetic constitution of NOD and NON differs, although they have been established from a common ancestor ICR mouse. Causes of divergence between NOD and NON mice are discussed.

Analysis of Variance↗

PubMed1987

[Discriminant analysis of hematological and serum biochemical values in cynomolgus monkey (Macaca fascicularis) bred and reared under the indoor individually-caged conditions].

The data on hematological and serum biochemical properties of laboratory-bred cynomolgus monkeys (Macaca fascicularis) at different ages were analyzed by discriminant analysis. All the animals had been bred and reared under uniform environmental conditions at Tsukuba Primate Center for Medical Science, N.I.H., Japan. The items used were as follows: red blood cell count (RBC), hematocrit value (Ht), hemoglobin concentration (Hb), mean corpuscular volume (MCV), white blood cell count (WBC), glutamic oxaloacetic transaminase activity (GOT), glutamic pyruvic transaminase activity (GPT), total protein concentration (TP), albumin concentration (ALB), albumin-globulin ratio (A/G), blood urea nitrogen (BUN), glucose concentration (GLU), total cholesterol concentration (TCHO), free cholesterol concentration (FCHO), triglyceride concentration (TG) and alkaline phosphatase activity (ALP). In total, 1086 animals in 10 age groups were examined. Data analyses were done with respect to the difference of sex. Discrimination was possible by Mahalanobis' generalized distance between centroids of groups. In canonical discriminant analysis (discriminant analysis with reduction of dimensionality), age was highly correlated to the value of the first canonical variate. From the approximate relative value of the eigenvector of the first canonical variate, the most discriminant variables are WBC, TP, ALB, A/G, TCHO, FCHO, TG, and ALP. It can be concluded that periodic measurement of these 8 parameters is necessary and sufficient to monitor the physiological conditions of growing monkeys.

Age Factors↗

PubMed1988

[Multivariate analysis of hematological and serum biochemical values in female cynomolgus monkeys (Macaca fascicularis) aged less than a year].

Hematological and serum biochemical data obtained from 91 laboratory-bred cynomolgus monkeys (Macaca fascicularis) aged 11 to 362 days were analyzed by the discriminant analysis. All animals used had been bred and reared under uniform environmental conditions at Tsukuba Primate Center for Medical Science, N. I. H., Japan. The examination items were as follows: red blood cell count (RBC), hematocrit value (Ht), hemoglobin concentration (Hb), mean corpuscular volume (MCV), white blood cell count (WBC), glutamic oxaloacetic transaminase activity (GOT), glutamic pyruvic transaminase activity (GPT), total protein concentration (TP), albumin concentration (ALB), albumin-globulin ratio (A/G), blood urea nitrogen (BUN), glucose concentration (GLU), total cholesterol concentration (TCHO), free cholesterol concentration (FCHO), triglyceride concentration (TG), alkaline phosphatase activity (ALP) and calcium concentration (Ca). The animals were divided into four groups (A: Suckling infants, less than 176 days old. B, C, D: Weanlings and juveniles, 121 to 220 days old, 221 to 280 days old, and 281 to 362 days old, respectively). Discrimination was possible among these four groups on the basis of the Mahalanobis' generalized distance. Regarding the canonical discriminant analysis (discriminant analysis with reduction of dimensionality), discrimination was possible. The suckling infant group could be discriminated from the juvenile groups by the first canonical variate. Concerning the juvenile groups, age was highly correlated to the value of the second canonical variate.2+ Judging from an approximate relative eigenvector value for the second canonical variate, the effective discriminant variables were WBC, TP, ALB, A/G, FCHO, TG, and ALP. It can be concluded that these eight parameters are important and useful for monitoring the physiologicals conditions of growing juvenile monkeys.

Aging↗

PubMed1988

[Discriminant analyses for pregnancy-related changes in hematological and serum biochemical values in cynomolgus monkeys (Macaca fascicularis)].

Hematological and serum biochemical data obtained from 45 non-pregnant and 142 pregnant cynomolgus monkeys (Macaca fascicularis) were analyzed by discriminant analyses. All animals used had been reared under uniform environmental conditions at Tsukuba Primate Center for Medical Science, N. I. H., Japan. The examination items were as follows: red blood cell count(RBC), hematocrit value(Ht), hemoglobin concentration(Hb), mean corpuscular volume(MCV), white blood cell count(WBC), total protein (TP), albumin (ALB), glucose (GLU), total cholesterol (TCHO), free cholesterol (FCHO), triglyceride (TG), and albumin-globulin ratio (A/G). The pregnant animals were divided into four groups according to their gestation ages (Group I: 1-40 days; II: 41-80 days; III: 81-120 days; and IV: more than 121 days). During pregnancy period (Groups II, III and IV), significant decrease of TP, ALB, TCHO, FCHO and TG was observed. RBC, Ht and Hb decreased in the last of the four periods of pregnancy (Group IV). Discrimination was possible between each of these four pregnant groups and the non-pregnant group on the basis of the Mahalanobis' generalized distance. To clarify the relationship among groups, canonical discriminant analysis (discriminant analysis with reduction of dimensionality) was carried out. As a result, the non-pregnant group and the pregnant I group could be clearly discriminated from the other pregnant groups (II, III, and IV) by the first canonical variate. Judging from the relative eigenvector value of each variable for the first canonical variate, the effective discriminant variables were RBC, Ht, Hb, MCV, TP and A/G.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1988

[Canonical discriminant analysis for pregnancy-related changes in hematological and serum biochemical values in tamarins (Saguinus spp].

Hematological and biochemical values obtained from 9 monkeys (Saguinus labiatus and S. mistax) during pre- and postpartum periods were analyzed by canonical discriminant analysis (discriminant analysis with reduction of dimensionality). All animals used were of wild origin and had been maintained under uniform environmental conditions at N. I. H., Japan. The items examined were as follows: white blood cell count (WBC), red blood cell count (RBC), hematocrit value (Ht), hemoglobin concentration (Hb), total protein concentration (TP), blood urea nitrogen (BUN), albumin concentration (ALB), albumin-globulin ratio (A/G), glutamic oxaloacetic transaminase activity (GGT), glutamic pyruvic transaminase activity (GPT), alkaline phosphatase activity (ALP) and total cholesterol concentration (CHO). The data obtained in the pre- and postpartum periods were divided into six chronological groups. The prepartum period was divided into Group I: weeks 15-10; Group II: weeks 9-7; Group III: weeks 6-4; and Group IV: weeks 3-0. The postpartum period was divided into Group V: weeks 0-4 and Group VI: weeks 5-7). In the later pregnancy period (Groups III and IV), significant decreases in RBC, Ht, Hb, TP and ALB, and a significant increase in CHO were observed. These values in the blood and serum continued after delivery (Groups V and VI). Results of canonical discriminant analysis showed that the value of the first canonical variate decreased according to the progress of pregnancy. The postpartum groups showed negative values. Although groups in the early

Analysis of Variance↗

PubMed1990

[A comparison of hematological and serum biochemical values between two groups of female cynomolgus monkeys reared under different conditions].

The influence of long term rearing conditions on the hematological and serum biochemical values in laboratory-bred female cynomolgus monkeys (Macaca fascicularis) was studied under the following two conditions. Group A: New born infants were nursed by their mothers for at least 12 weeks after birth. After weaning, four monkeys of approximately equal age and body weight were kept in a relatively small cage (90 cm W x 60 cm D x 60 cm H) and reared to five years of age. These rearing conditions are commonly used in the breeding program of our primate center. Group B: One male and five females of wild origin were introduced into a relatively large cage (180 cm W x 180 cm D x 160 cm H). Female monkeys born in these cages were used in this study. All of them were reared by their own mothers and grew well in these cages. Male monkeys born in these cages were removed at about 3.5 years of age. Hematological and serum biochemical values between the two groups in each age class were compared and analyzed by the canonical discriminant analysis (the discriminant analysis with reduction of dimensionality). Age correlated highly with the value of the first canonical variate. The second canonical variate detected a difference in the blood hematology and biochemistry probably induced by the difference in rearing conditions.

Age Factors↗

PubMed1991

[Canonical discriminant analysis for hematological and serum biochemical changes during pregnancy period in squirrel monkeys (Saimiri sciurea)].

Hematological and serum biochemical data obtained from non-pregnant, pregnant and post-partum squirrel monkeys (Saimiri sciurea) were analyzed by canonical discriminant analysis (discriminant analysis with reduction of dimensionality). All animals were of wild origin and had been maintained under uniform environmental conditions at Tsukuba Primate Center for Medical Science, N.I.H., Japan. Months were standardized by the day of parturition. The calculated arithmetic means and standard deviations were listed for each item of measurement performed. Items detected statistically significant difference (p less than 0.01) between months were as follows: red blood cell count (RBC), mean corpuscular volume (MCV), hematocrit value (Ht), hemoglobin concentration (Hb), white blood cell count (WBC), albumin concentration (ALB), blood urea nitrogen concentration (BUN), total cholesterol concentration (T-CHO), triglyceride concentration (TG), alkaline phosphatase activity (ALP) and calcium concentration (Ca). Results of canonical discriminant analysis showed that the value of the first canonical variate (Z1) decreased from the early period of pregnancy to the middle period, and that the second canonical variate (Z2) decreased from the middle period of pregnancy to the end of pregnancy. The meaning of their changes were discussed.

Alkaline Phosphatase↗