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Results for “computational morphology”

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At least 577 records · Page 32Linked to original sources

PubMed2006

[Is there an association between sperm normal morphology and their kinetic displacement?].

OBJECTIVE: To evaluate if there exist an association between the % of normal forms and the kinetic characteristics in human spermatozoa MATERIAL AND METHODS: A retrospective study was performed to analyze semen samples of 203 patients by Computer Assisted Semen Analysis. Sperm morphology was evaluated by the aid of a micrometric objective according to strict criteria. Only the patients presenting >20 x 106 sperm/ml and > 50% of progressive motility were included. Data from 168 patients were divided according to the % of normal forms in three groups a) <4% (n=22), b) between 4-13% (n=89) and c) >14% (n=57). Data collected among groups were compared. In order to select a motile sperm population 35 samples were treated by a discontinuous gradient and the % of normal forms as well as motility parameters evaluated before and after selection. RESULTS: The kinetic analysis showed that sperm concentration, the % of motile and rapid spermatozoa (>25 microm/s) as well as the average path velocity (VAP) and the lateral head displacement (LHD) were increased in association with the % of normal spermatozoa presenting the lowest values in the group <4% with respect to the > or = 14% group, (p<0.05). Linearity (LIN) remained constant among groups. Kinetic parameters and sperm morphology were significantly increased (p<0.0001) in the selected samples Results showed that the use of gradients even in teratozoospermic samples improves significantly the % of normal forms respect to baseline values (p<0.0002). CONCLUSIONS: Our results would support the hypothesis that morphologically better spermatozoa would be associated with those with better movement parameters measured in an objective way. In this manner we could suggest that in vivo the best spermatozoa would comprise one "elite" in the journey through the fertilization site.

Humans↗

PubMed1998

Modeling and simulating morphological evolution in an artificial life environment.

This paper presents a computer-based environment designed to study biological evolution considering morphological aspects. It was inspired on cellular automata and evolutionary algorithm principles. Simple rules are used to determine the genotype and phenotype of individuals and their relationships with behavioral aspects in a square matrix environment, where individuals can evolve. Two methods to simulate mutational errors and to introduce variability of mutations are discussed. A series of four simulations show that the model promotes phenotype evolution depending on the distribution of food over the environment; morphology evolved as to favor movement of the individuals towards the portion of the environment in which the food has been distributed or to capture falling food.

Algorithms↗

PubMedDate not supplied

A system for computer-assisted design of stent-grafts for aortic aneurysms using 3-D morphological models.

A three-dimensional model was constructed from helical CT images for abdominal aortic aneurysm (AAA) and thoracic aortic aneurysm (TAA). A stent-graft was designed and positioned endoluminally on the computer. One hundred and nine stent-grafts for 101 patients were designed by this method and deployed well in all patients. The design time was reduced from 4 to 0.5 hr.

Adult↗

PubMed1981

Morphometric studies on mouse bone using a computer-based image-analysis system.

The morphological structure of the ilium, femur, third lumbar vertebra and a central caudal vertebra of the female CBA mouse has been studied using 5 micrometer thick, plastic embedded, transverse and longitudinal sections. The sections were analysed on a Quantimet 720, system 30, image analyser connected on-line to a PDP11 computer. Separate endosteal and periosteal surface to volume ratios were calculated for each position of sampling in each bone. For this calculation the anisotrophy of the bone was estimated from measurements of mean chord lengths in longitudinal sections of the bone using a new analytical technique. Chord length distributions in transverse sections of bone were also measured and the relevance of such measurements to the study of morphological changes in the bone and its included marrow are briefly discussed.

Animals↗

PubMed2006

Monitoring individual morphological changes over time in ovariectomized rats by in vivo micro-computed tomography.

The ovariectomized (OVX) rat is a well established model for osteoporosis research. The recent development of in vivo micro-computed tomography (micro-CT) provides new possibilities to monitor individual bone changes over time. The purpose of this study was to establish the normal time course of bone loss in the OVX rat model, and to determine the ability to detect morphological changes in vivo compared to cross-sectional study designs where animals are sacrificed at each time point. Eight-month-old female Wistar rats were randomly assigned to one of two groups: OVX (N = 10) or sham-operated (N = 10). In vivo micro-CT scanning of the right proximal tibial metaphyses occurred at 1-month intervals for 6 months. Morphological analyses were performed at each time step for every animal, and a two-way ANOVA with repeated measures was used to analyze the data. A second statistical analysis was performed without repeated measures for analysis as a cross-sectional study design. The repeated measures analysis was more sensitive to early changes than the cross-sectional study analysis. Changes were detected by longitudinal analysis in the sham-operated and OVX animals over time (P < 0.001) with the exception of trabecular separation in the sham animals. The OVX animals had decreases of bone volume ratio of 33% after 1 month, and 72% after 3 months relative to baseline measurements. Significant changes in bone volume ratio, trabecular number and separation were detected early using a longitudinal analysis, thus in vivo assessment is well poised to enable the study of early treatment protocols on the effects of bone architecture. The in vivo analysis found significant changes in the sham animals which were not detected by the cross-sectional analysis, and the changes to the OVX animal morphology was detected sooner. A substantial variation of baseline morphometry within the homogenous group of rats and response to OVX was observed, thus emphasizing the advantage of performing in vivo analysis where each animal acts as its own control. These data provide new insight into individual bone changes following OVX, and can be used as baseline information upon which future in vivo studies can be designed.

Age Factors↗

PubMed2003

Endoluminal repair of abdominal aortic aneurysm prevents enlargement of the proximal neck: a 9-year life-table and 5-year longitudinal study.

OBJECTIVE: Endoluminal repair of abdominal aortic aneurysm (AAA) is predicated on stability of the proximal neck of the aneurysm. Reports on morphologic changes in the proximal neck after endoluminal repair of AAA have thus far been limited in duration to 3 years or less. The aim of this study was to document changes in diameter of the proximal neck of AAA in a group of patients who had undergone endoluminal repair between 5 and 9 years previously. METHODS: Between May 1992 and December 1996, 61 patients with AAA were treated with endoluminal repair by the senior author. The following patients were excluded from the study group: those requiring primary conversion to open repair at the original operation (n = 8), those with false aneurysm (n = 1), and those with dissection in the proximal neck (n = 1). Fifty-one patients (48 men and three women) with a mean age of 71 years remained in the study group. The endoprostheses used were modified Parodi (n = 4), Endovascular Technologies (n = 14), White-Yu (n = 10), Stentor/Vanguard (n = 21), and Bard 1996 prototype (n = 2). Morphologic changes in the proximal aortic neck were studied with contrast computed tomographic scan with the methodology recommended by the Ad Hoc Committee for Standardized Reporting Practices for Endovascular AAA Repair (revised version). The maximum transverse diameter of the proximal neck was measured 1 cm below the most inferior renal artery. A Kaplan-Meier analysis was performed showing the proportion of patients at risk with a demonstrated enlargement of the neck at each interval of time compared with the predischarge computed tomographic scan. A longitudinal study of morphologic changes in the proximal aortic neck was also undertaken in 28 patients with successful endoluminal repair who survived 5 years. RESULTS: The Kaplan-Meier curve showed a probability of no dilatation of the proximal neck of 0.943 at 7 years after endoluminal AAA repair. Of 28 patients with 5 years of follow-up after discharge, only two had increases in the diameter of the proximal neck greater than 2 mm. The endograft in both patients had undergone migration before any proximal neck dilation. A paired t test showed that the overall average increase of 0.4 mm (standard error, 0.3 mm) in these 28 patients was not statistically significant (P =.23). CONCLUSION: A high probability (0.943 at 7 years) exists of no enlargement of the proximal neck of AAA after endoluminal repair. We hypothesize that endografts positioned correctly immediately below the renal arteries protect the proximal neck from dilatation in a manner that does not occur after open repair of AAA.

Aged↗

PubMed1983

[Computer tomographic findings in portal hypertension caused by liver cirrhosis. 1. Morphologic changes--qualitative and quantifiable parameters].

The CT findings in 80 patients with confirmed portal hypertension due to intrahepatic block were analysed retrospectively. The findings included ascites, hypo-dense areas in the liver, nodular or irregular liver contour, the inability to define intrahepatic portal vessels with narrow window settings, the so-called "kissing" sign and evidence of hepato-fugal collaterals and thickening of the wall of the oesophagus. Electronic measurements of various organs (liver, spleen) and vessel diameters (portal vein, superior mesenteric vein) provide parameters which permit classification of patients into the cirrhotic group, as compared with a control group. The statistical significance of this classification was checked by the Kolmogoroff-Smirnoff test.

Ascites↗

PubMed2005

Theoretical study on the body form and swimming pattern of Anomalocaris based on hydrodynamic simulation.

Anomalocarid arthropod is the largest known predatory animal of middle Cambrian. Studies on Anomalocaris have been piled up in the past two decades since the first reasonable reconstruction had achieved in 1980s. Recent finding of legs beneath lobes on Parapeytoia Yunnanensis shows arthropod affinities, however, many researchers believe that it must be a powerful swimmer by the use of developed lobes. In this work, we investigate swimming behaviour of Anomalocaris in water by performing hydrodynamical calculation. As a result of simulation using moving particle method possible swimming motion of Anomalocaris is obtained. In the computer we can change the morphology from known bauplan of Anomalocaris found as fossil record. It makes us possible to discuss on the variants of Anomalocaris at the intermediate state of evolution process. Such new methodology using computer reveals how and from where Anomalocaris evolved.

Animals↗

PubMed1997

A Monte Carlo calculation of cell inactivation by light ions.

This study simulates the exposure of V79 Chinese hamster fibroblasts to low-energy protons, deuterons and alpha-particles in the LET range 10-200 keV/microm. The starting assumption is that the induction of clustered lesions in DNA is a fundamental step for cell inactivation. A non-homogeneous cell population was simulated by a computer program, using as input measured morphological parameters reported in the literature. Variations in the number of traversals through each cell of the population and in the length of the traversal, depending on actual nuclear thickness and position of the traversal, the energy spread of the incident beam, and the change of LET along the tracks were included in the simulation. Microdosimetric spectra were computed and compared with spectra obtained neglecting particle slowing-down and stochastic aspects of cell morphology. Simulated cell survival was estimated under the assumption that surviving cells are those with no clustered DNA lesions or no passages. The main features of experimental RBE versus LET and particle type were reproduced by the simulations. The influence of stochastic aspects of target-cell morphology and of the energy of the incident particles on survival were investigated under different assumptions about the correlation between morphological parameters. Results support the hypothesis of a relevant role of clustered DNA damage in cell killing and point out the importance of target-cell morphology and its variability in beam dosimetry and computer simulations of low-energy particle radiation effects.

Animals↗

PubMed2003

Automated biofilm morphology quantification from confocal laser scanning microscopy imaging.

In spite of the immediate visual appeal of confocal laser scanning microscopy images, the extraction of accurate reconstitutions of biofilm morphology requires a lengthy and computational intensive succession of processing steps. However, once performed, it provides ample reward by enabling the quantitative study of biofilm structure. A software suite of image processing tools for full automation of biofilm morphology quantification was developed by integrating preprocessing, segmentation and morphology quantification operations. This software toolbox was implemented in a web server and a user friendly interface was developed to facilitate image submission, storage and sharing, its access being unrestricted for scientific applications. The image bioinformatics tool which results from the integration of the processing operations can be accessed at http://www.itqb.unl.pt:111/clsmip/. Its use is described in this paper and is illustrated with an example of processing of experimental data describing the growth of a mixed species dentrifying biofilm.

Automation↗

PubMed1986

Sex differences in the shape of the sexually dimorphic nucleus of the preoptic area and suprachiasmatic nucleus of the rat: 3-D computer reconstructions and morphometrics.

Three-dimensional images of nuclei facilitate morphological comparisons between differing animal groups. As revealed by computer-assisted techniques, the greater volume in male rats of the sexually dimorphic nucleus of the preoptic area was not proportional in all directions. The nucleus was more elongated in males than females, indicating a sex-dependent shape. This study also indicated that the volume of the suprachiasmatic nucleus was larger in males.

Animals↗

PubMed2005

Biogeneric tooth: a new mathematical representation for tooth morphology in lower first molars.

A mathematical representation of tooth morphology may help to improve and automate restorative computer-aided design processes, virtual dental education, and parametric morphology. However, to date, no quantitative formulation has been identified for the description of dental features. The aim of this study was to establish and to validate a mathematical process for describing the morphology of first lower molars. Stone replicas of 170 caries-free first lower molars from young patients were measured three-dimensionally with a resolution of about 100,000 points. First, the average tooth was computed, which captures the common features of the molar's surface quantitatively. For this, the crucial step was to establish a dense point-to-point correspondence between all teeth. The algorithm did not involve any prior knowledge about teeth. In a second step, principal component analysis was carried out. Repeated for 3 different reference teeth, the procedure yielded average teeth that were nearly independent of the reference (less than +/- 40 microm). Additionally, the results indicate that only a few principal components determine a high percentage of the three-dimensional shape variability of first lower molars (e.g. the first five principal components describe 52% of the total variance, the first 10 principal components 72% and the first 20 principal components 83%). With the novel approach presented in this paper, surfaces of teeth can be described efficiently in terms of only a few parameters. This mathematical representation is called the 'biogeneric tooth'.

Algorithms↗

PubMed2005

Data mining tools for the Saccharomyces cerevisiae morphological database.

For comprehensive understanding of precise morphological changes resulting from loss-of-function mutagenesis, a large collection of 1,899,247 cell images was assembled from 91,71 micrographs of 4782 budding yeast disruptants of non-lethal genes. All the cell images were processed computationally to measure approximately 500 morphological parameters in individual mutants. We have recently made this morphological quantitative data available to the public through the Saccharomyces cerevisiae Morphological Database (SCMD). Inspecting the significance of morphological discrepancies between the wild type and the mutants is expected to provide clues to uncover genes that are relevant to the biological processes producing a particular morphology. To facilitate such intensive data mining, a suite of new software tools for visualizing parameter value distributions was developed to present mutants with significant changes in easily understandable forms. In addition, for a given group of mutants associated with a particular function, the system automatically identifies a combination of multiple morphological parameters that discriminates a mutant group from others significantly, thereby characterizing the function effectively. These data mining functions are available through the World Wide Web at http://scmd.gi.k.u-tokyo.ac.jp/.

Computer Graphics↗

PubMed2002

Anisotropic ordering in sheared binary fluids with viscous asymmetry: experiment and computer simulation.

Optical measurements of the structure and morphology of phase-separating polymer blend under simple shear flow have been performed and the results are compared with computer simulations of sheared phase-separating binary mixtures with viscous asymmetry in the fluid components. Information about the structure is obtained from the two-point composition correlation function. Both experiment and simulation suggest subtle differences in the shear response depending on whether the more viscous phase is dispersed or continuous. Measurements of the string width along the neutral direction suggest power-law decay in the shear rate with an exponent of 1/3 when the more viscous phase is dispersed. The simulations suggest that the mean string width, measured along the velocity-gradient direction in the two-dimensional model calculation, exhibits power-law decay in the shear rate with an exponent of 1/3 independent of which phase is dispersed.

Journal Article↗

PubMed1990

Right ventricular function and three-dimensional modeling using computer-aided design.

Right ventricular (RV) volumetric and morphological analysis is complicated by the trabeculations and geometric configuration of the RV chamber. To improve RV analysis, custom computer-aided design programs were employed to obtain RV volumes and three-dimensional models from biplane ventriculograms. Biplane RV ventriculograms were analyzed from 14 anesthetized dogs and 22 RV casts. Computed volumes were highly correlated with reference RV volumes (r = 0.98, n = 36, P less than 0.01) with a range of 5-73 ml. Three-dimensional wire-frame and solid models constructed from the ventriculographic images provided excellent detail and a new perspective in chamber shape. This modeling technique was then used to examine RV volumes, geometric conformation, and regional shortening in 10 pigs during inotropic stimulation and preload reduction. Changes in RV volumes, ejection fraction, and regional motion were detected as well as alterations in chamber conformation. In summary 1) computer-aided design offers an accurate and simplified means to compute RV volumes using basic microcomputer equipment, and 2) three-dimensional reconstruction provided a unique view of RV geometry and a means to examine regional RV function.

Animals↗

PubMed1988

[Detection and evaluation of data in perinatal diagnosis using a personal computer].

Imaging, biochemical, genetic, clinical, histological, cytological and morphological examinations methods are practised in perinatal diagnostics. We propose a system of data registration and processing using a personal computer regarding both prenatal therapeutic measures. Data are collected as data store "perinatal diagnostic" which may be expanded prospectively at any time.

Female↗

PubMed1991

Straight and paired helical filaments in Alzheimer disease have a common structural unit.

The presence of abundant neurofibrillary tangles in certain areas of the brain constitutes one of the defining pathological characteristics of Alzheimer disease. The predominant component of the tangle is an abnormal fibrous assembly known as the paired helical filament (PHF). The PHF is formed by a twisted double-helical ribbon of subunits that gives rise to an image alternating in width between 8 nm and 20 nm with a cross-over spacing of 80 nm. Also found in tangles is the straight filament (SF), a different kind of abnormal filament, about 15 nm wide, that does not exhibit the marked modulation in width shown by the PHF. It is reported herein that PHFs and SFs form hybrid filaments displaying both morphologies, that PHFs and SFs share surface epitopes, and that computed maps reveal a similar C-shaped morphological unit in PHFs and SFs, though differing in relative arrangement in the two types of filament. The observations imply that the SF is a structural variant of the PHF and establish a common unit of assembly for these two pathological filaments.

Alzheimer Disease↗

PubMed2001

Structuring of parameters for assessing vertebral bone strength by star volume analysis using a morphological filter.

Based on the relationship between bone strength, trabecular skeletal structure, and bone mineral density (BMD), structure parameters for assessing vertebral bone strength were studied using 18 cancellous bone blocks from the third lumbar vertebra of elderly persons. The trabecular bone pattern of each bone block was binarized into a trabecular skeletal pattern by computed radiography (CR) using a morphological filter. The binarized trabecular skeletal pattern was quantified into a trabecular skeletal pixel percentage (SKP; volume parameter of the trabecular skeletal signal component) and trabecular skeletal star volume (Vt; connection parameter of the trabecular skeletal structure) by star volume analysis. Then, the BMD and elasticity of each bone block were measured by dual X-ray absorptiometry and mechanical tests to determine the correlation between SKP and Vt. In the present study, no significant correlations were observed between BMD and elasticity. Elasticity differed greatly between some bone blocks even though BMD was essentially the same. Grid-like skeletal patterns consisting of vertical and horizontal continuous lines showed higher elasticity. SKP showed higher correlations with elasticity than BMD in subset (n = 2-7) and sumset images, although the fluctuation range was narrow. Meanwhile, Vt showed higher correlations with elasticity than SKP in subset (n = 1-6) and sumset images. Vt showed stronger correlations with elasticity than SKP. This fact indicates that strong relationships exist between the connectivity of trabecular skeletal structure and bone strength. Because the SKP-BMD and Vt-BMD correlations are weak, the influences exerted by SKP and Vt seem to be independent of the influence of BMD on the bone strength of vertebra obtained from persons with advanced age. These results indicate that SKP and Vt obtained by star volume analysis using a morphological filter are effective as structure parameters for analyzing the bone quality of lumbar vertebra.

Aged↗