PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “computational morphology”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed1997

Sperm head morphometry analysis of ejaculate and dismount stallion semen samples.

The evaluation of seminal characteristics is important in the clinical detection of stallion subfertility. Conventional semen evaluation includes subjective determination of sperm concentration, motility, and gross morphology. Due to the subjectivity and variability of the manual morphology assessment, computer automated sperm morphology analyses has been developed. Computer automated sperm morphology analysis was applied in the current study to determine if the morphometric measurements of sperm heads from collected and dismount samples of the same ejaculate were similar. If the post-ejaculate dismount sample is representative of the entire ejaculate, this sample may be utilised in determining the fertility of the ejaculate. Ejaculate samples were collected from ten stallions using an artificial vagina. Post-ejaculate dismount samples of the same ejaculate were taken from the head of the penis. A thin smear of the collected and dismount samples were prepared onto microscope slides and spermatozoa were stained for 40 min in haematoxylin. At least 200 properly digitised sperm heads from each slide were analysed using computer automated sperm morphometry analysis. The mean values for length, width, width/length, area, and perimeter were recorded from each analysis of collected and dismount samples and compared by paired t-test. The coefficients of variation of each analysis was also recorded and compared between collected and dismount samples by paired t-test. No significant differences (P > 0.10) in any measurements were found between collected and dismount samples. The mean values for all stallions for collected and dismount samples were length = 5.96 microM and 6.06 microM, width = 2.95 microM and 2.98 microM, width/length = 0.49 and 0.49, area = 13.31 microM2 and 13.65 microM2 and perimeter = 15.54 microM and 15.74 microM respectively. No significant differences were detected in the coefficients of variation of sperm head measurements from collected and dismount samples. These results indicate sperm head measurements from dismount semen are representative of those of the ejaculate. Hence, sperm head measurements of dismount samples may be viably applied to studies of fertility or in case of clinical fertility assessment. This finding will further assist in the development of normal sperm head morphometry criteria in the stallion. Clinically, a slide can be prepared in the field after natural services matings and analysed accurately and objectively by ASMA.

Animals↗
PubMed2003

Study of unipolar electrogram morphology in a computer model of atrial fibrillation.

INTRODUCTION: Electrograms exhibit a wide variety of morphologies during atrial fibrillation (AF). The basis of these time courses, however, is not completely understood. In this study, data from computer models were studied to relate features of the signals to the underlying dynamics and tissue substrate. METHODS AND RESULTS: A computer model of entire human atria with a gross fiber architecture based on histology and membrane kinetics based on the Courtemanche et al. atrial model was developed to simulate paced activation and simulated AF. Unipolar electrograms were computed using a current source approximation at 256 sites in right atrium, to simulate a mapping array. The results show the following: (1) In a homogeneous and isotropic tissue, the presence of highly asymmetric electrograms is rare (<2%), although there is a marked variability in amplitude and symmetry. (2) The introduction of anisotropy increases this variability in symmetry and amplitude of the, electrograms especially for propagation across fibers. The percentage of highly asymmetric electrograms increases to 12% to 15% for anisotropy ratios greater than 3:1. (3) Multiphasic and fractionated electrograms are rarely seen in the model with uniform properties but are more common (15%-17%) in a model including regions with abrupt changes in conductivity. Beat-to-beat variations in the occurrence of multiphasic signals are possible with fixed anatomic heterogeneity, due to beat-to-beat variations in the direction of the wavefront relative to the heterogeneity. CONCLUSION: Analysis of the amplitude and symmetry of unipolar atrial electrograms can provide information about the electrophysiologic substrate maintaining AF.

Algorithms↗
PubMed1980

[Morphologic verification in computer tomography of the brain].

A comparison of computer-aided tomograms of the brain with the results of morphological examinations of the latter in 51 autopsy cases was carried out. The causes of the death were brain infarctions, hemorrhages, and tumours. It was found that roentgenological diagnosis of cerebral infarctions entailed no difficulties, if the examinations were performed within 24 hours after the disease onset and the focus size was over 1 to 2 cm. There were some difficulties in diagnosing small foci in the brain stem and in the cortex of brain hemispheres as well as infarctions with hemorrhages irrespectively of their size and location. The diagnoses of cerebral hemorrhages were rather precise in the early stages of hemorrhagic strokes, but extremely difficult later, in a definite stage of the hemorrhagic focus organization when computer-aided tomography revealed densities characteristic for unaffected brain. A high diagnostic efficiency of the computer-aided tomography was noted in brain tumours. Certain difficulties sometimes arose in determining the character of the tumour in cases of multiple of small-size foci. The morphological verification of the results of the computer-aided brain tomography is of a decisive importance for developing roentgenomorphological criteria for diagnosing CNS pathologies with the aid of this method, and contributes to further improvement of the latter.

Brain↗
PubMed1993

[Morphological and computer-tomographic analysis of reparative regeneration of the tibia by distraction osteosynthesis].

Morphological & computerized tomography analysis of tibial reparative regeneration in distraction osteosynthesis was performed in 12 & 25 patients consequently. The authors discuss the correlation between the two kinds of the data & show that development of bone regeneration with restoration of anatomical form & structure of the reconstructing tubular bone occurs in the place of osteotomy.

Biopsy↗
PubMed1998

Sperm morphology evaluated by computer (IVOS) cannot predict the fertilization rate in vitro after intracytoplasmic sperm injection.

OBJECTIVE: To evaluate sperm morphology assessment using the IVOS (Hamilton-Thorne Research Version 3 Dimension Program, Beverly, MA) system in prediction of fertilization rate in vitro after intracytoplasmic sperm injection (ICSI). DESIGN: A prospective clinical study. SETTING: Diagnostic andrology laboratory and assisted conception service. PATIENT(S): Thirty-five patients from the ICSI program were evaluated. Semen samples were analyzed using a computerized system for conventional semen parameters, sperm movement characteristics, and sperm morphology. Only patients with three or more metaphase II (MII) oocytes available were studied. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Fertilization rates in vitro after ICSI were compared according to the sperm morphology obtained from the IVOS system. RESULT(S): Linear regression analysis of fertilization rates against the sperm parameters assessed by computer (IVOS), which included conventional semen parameters, sperm movement characteristics, percentage of normal sperm morphology, and percentage of each specific abnormal sperm morphology, did not reveal any significant correlations. The mean (+/- SEM) fertilization rates in the healthy prognosis group (normal sperm morphology > or = 4%) and poor prognosis group (normal sperm morphology < or = 4%) were 82.4 +/- 4.0% and 75.0 +/- 3.8%, respectively. There was no statistically significant difference in the mean fertilization rate between both groups. Moreover, no statistically significant difference was found in overall fertilization rates in vitro between the two prognosis categories (79.6% versus 78.0%). CONCLUSION(S): Sperm morphology obtained from the IVOS system is not related to the outcome of ICSI and cannot be used for prediction of fertilization rate in vitro after ICSI.

Adult↗
PubMedDate not supplied

[The possibilities for detecting pelvic injuries in children (comparative x-ray, computed tomographic and morphological studies)].

The authors analyze the possibility of detecting pelvic injuries in children on an inpatient basis by x-ray examination and computer-aided tomography and by morphological methods during forensic medical autopsy. A total of 146 cases are analyzed. X-Ray examination helped diagnose only 47.37% of all injuries in children with pelvic traumas. The informative value of the x-ray method may be improved if such factors as the presence of residual deformation with manifest asymmetry of the small pelvis entry are taken into consideration. If pelvic injuries are suspected in children, plane computer-aided tomography is advisable, for it permits the diagnosis of 76.32% injuries.

Autopsy↗
PubMed2001

The need for integrating neuronal morphology databases and computational environments in exploring neuronal structure and function.

Neurons connect to each other through a myriad of dendritic and axonal arborisations. Dendritic structures provide the substrate for integration of postsynaptic potentials and control of action potential generation. Axonal structures provide the substrate for action potential dissemination and signalling to target neurons. The morphological complexity of dendritic arborisations is assumed to play a critical role in the transformation of spatio-temporal patterns of postsynaptic potentials into time-structured series of action potentials. Although these transformations lie at the basis of information processing in the brain, it is still far from understood how their details are influenced by dendritic shape. To facilitate research in this area, it is necessary that data on both the morphology and electrical properties of neurons, as well as computational tools for analysis, become available in an integrated way. This requires a combined effort from the fields of informatics and neurosciences (together called neuroinformatics) in order to create data acquisition, databasing and computational tools. Focusing on neuronal morphology, this chapter will give a brief review of the current neuroinformatics developments in both reconstruction techniques, morphological quantification, modeling of morphological complexity, modeling of function and the need for databasing neuronal morphologies. Additionally, one of the dendritic modeling approaches is described in more detail in the Appendix.

Animals↗
PubMed1985

Computer-aided reconstructive morphology of the baboon abducens nucleus.

Our previous effort at reconstructive morphology included the marriage of the horseradish peroxidase (HRP) neurohistochemical method to a Lucite plate reconstruction technique. Limitations imposed by this combination of methods has led us to develop a computer-based system that utilizes image-processing techniques and the data obtained from HRP-processed serial light microscope sections. Labeled neurons of the baboon abducens nucleus were identified by HRP conjugated to wheat ger agglutinin. Using the resulting serial sections and a unique imaging process involving a pattern recognition algorithm, our computer-based system automatically differentiates neuronal from nonneuronal features, delineates the surface boundaries of the neuronal population, and then assembles these serial sections into a solid three-dimensional structure that can be rotated and further analyzed. A computer-generated solid model of this neuronal population has been reconstructed and reproduced in a two-dimensional publishable format. It is anticipated that with further development this system will be able to utilize data from the same specimen to study spatial relations through three-dimensional reconstruction, as well as to study the quantitative morphology of a neuronal population. Other computer-aided systems are noted, as are the advantages and shortcomings of the present method.

Abducens Nerve↗
PubMed1995

Brain morphology assessed by computed tomography in patients with geriatric depression, patients with degenerative dementia, and normal control subjects.

To determine whether patients with geriatric depression have specific alterations in brain morphology, internal (ventricles) and external (frontal, temporal, and parieto-occipital) components of the cerebrospinal fluid (CSF) spaces were examined. Planimetric measurements of computed tomographic (CT) scans from patients with geriatric depression were compared with measurements from two age- and sex-matched control groups: normal control subjects and patients with primary degenerative dementia. Scans of 34 patients (6 men, 28 women; mean age = 70.7 years) who met DSM-III-R diagnostic criteria for major depression, 29 patients with DSM-III-R primary degenerative dementia (8 men, 21 women; mean age = 71.2 years), and 43 nonpsychiatric control subjects (10 men, 33 women; mean age = 70.8 years) were evaluated. The areas of the frontal and parieto-occipital sulci, the Sylvian fissures, and the lateral and third ventricles were measured separately for the right and left hemispheres. Compared with the control subjects, patients with geriatric depression revealed a remarkable enlargement (up to 125%) of the left Sylvian fissure on several levels and a more subtle enlargement of the ventricles, cortical sulci, and right Sylvian fissure (20-50%). The laterality index differed significantly between depressed patients and normal control subjects (but not between the demented patients and the normal control group) only for the Sylvian fissure. Demented patients showed a considerable brain atrophy that affected all CSF components (enlargement of 30-160%) but the left temporal region was less affected than in the depressed patients. Compared with the findings in geriatric depression, ventricular enlargement was significant in dementia.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMedDate not supplied

Hypotrophy of the soleus muscle in man after achilles tendon rupture. Discussion of findings obtained by computed tomography and morphologic studies.

Seven athletes (age range, 35 to 43 years), who sustained total subcutaneous ruptures of the Achilles tendon 2 to 5 cm above its distal insertion, were treated surgically with suturing of the tendon, immobilization of the leg and foot for 6 weeks, and cast changes so as to increase the dorsiflexion of the foot. Needle biopsies were obtained several times from the soleus muscles of both the injured and uninjured legs at a depth of about 5 cm. The cross-sectional area was measured by computed tomography at the same level the tissue was obtained by biopsy. Results of morphologic studies revealed a selective Type I fiber atrophy of the soleus muscle. Computed tomography revealed a 23% decrease in the area of the calf muscles and a 11% total reduction in the cross-sectional area of the calf (about the middle, where the gastrocnemius muscle is transformed into a tendon and where the soleus lies superficially). Mere measurement of the circumference of the calf is judged to be a poor criterion of muscle atrophy when compared with these other means of evaluation of atrophy. The evidence compiled during this study suggests that prompt surgical treatment of Achilles tendon ruptures, with cast changes several times during the period of immobilization and with tension maintained on the muscle, is the most effective treatment regimen we have found for this injury.

Achilles Tendon↗
PubMed1988

Marchiafava-Bignami disease. A correlative computed tomography and morphological study.

The subacute development of Marchiafava-Bignami disease (MBD) is reported in a 60-year-old patient from Southern Germany with a history of chronic alcoholism and severe malnutrition. Computed tomography scans showed progressive white matter destruction over a period of 8 months, ranging from diffuse hypodensities to well-delineated, strongly hypodense areas in the central hemispheric white matter of both frontal and parietal lobes and in the corpus callosum. Autopsy revealed an identical pattern of demyelinated, partially necrotic lesions in addition to small cystic necroses in the genu corporis callosi. The temporal evolution of MBD, criteria for early diagnosis and pathogenetic aspects are discussed.

Alcoholism↗
PubMed2006

Maxillary sinus septa: prevalence, height, location, and morphology. A reformatted computed tomography scan analysis.

BACKGROUND: The sinus lift technique may be difficult to perform if an aberrant sinus anatomy is encountered during surgical exposure, such as when a septum is present on the sinus floor. The objective of this study was to determine the prevalence, size, location, and morphology of maxillary sinus septa in the atrophic/edentulous and non-atrophic/dentate maxillary segments. METHODS: The sample population consisted of 100 patients (41 women and 59 men, with a mean age of 50 years, ranging between 19 and 87 years) for whom treatment was being planned for implant-supported restorations. Reformatted computerized tomograms (CT) from 200 sinuses were analyzed using imaging software. RESULTS: The prevalence of one or more septa per sinus was found to be 26.5% (53/200), 31.76% (27/85), and 22.61% (26/115) in the overall study population and the atrophic/edentulous and the non-atrophic/dentate maxillary segments, respectively. In the analysis of the anatomic location of the septa within the sinus, it was revealed that 15 (25.4%) were located in the anterior region, 30 (50.8%) in the middle region, and 14 (23.7%) in the posterior region. The measured heights of the septa varied among the different areas. The mean heights of the septa were 1.63 +/- 2.44, 3.55 +/- 2.58, and 5.46 +/- 3.09 mm in the lateral, middle, and medial areas, respectively. CONCLUSIONS: It can be inferred that there is a wide anatomical variation in the prevalence, size, location, and morphology of maxillary sinus septa, irrespective of the degree of atrophy. Therefore, to prevent the likelihood of complications arising during sinus augmentation procedures, a thorough and extensive understanding of the anatomic structures inherent to the maxillary sinus is indispensable.

Adolescent↗
PubMed1988

Quantification and classification of human sperm morphology by computer-assisted image analysis.

A quantitative, semi-automated method for classifying human sperm based on objective measurements of head shapes and sizes has been developed. Air-dried smears of semen from eight healthy men were stained with the Feulgen reaction and 283 sperm were selected as prototypic examples of the 10 morphology classes used in our classification system. Sperm heads were imaged through a microscope (NA = 1.3), sampled at 0.125-micron intervals, and measured on an image analysis system. Measurements included stain content, length, width, perimeter, area, and arithmetically derived combinations. Additionally, each sperm image was optically sectioned at right angles to its major axis to give a measure of lengthwise heterogeneity of shape. Linear stepwise discriminant analysis was used to identify the more powerful parameters and to create a model employing eight parameters. The jackknifed classification procedure distinguished normal from abnormal sperm with 95% accuracy and correctly assigned 86% of the sperm to one of 10 shape classes. Most of the misclassification errors occurred among closely related classes. The results demonstrate the ability of automated image analysis to classify individual sperm into clinically familiar shape categories.

Humans↗
PubMed1997

Constancy, uniformity and symmetry of living systems: the computational functions of morphological invariance.

Living systems, whether organs or entire organisms, display various forms of morphological invariance. Why? These phenomena are studied here from the Proto-Cognitive perspective, according to which evolution proceeds by processing information about the environment. The evolution of constancy, uniformity and symmetry is studied in detail. The study later focuses on the invariances of the plant's leaves and it is proposed that these invariances play a crucial role in the plant's development of individual form. Experiments are proposed to test these hypotheses. Morphological invariance is further examined in the light of thermodynamics and information theory. New thermodynamic restrictions are imposed on the processes of measurement and information recording. Uniformity and symmetry are shown to meet these restrictions.

Animals↗
PubMedDate not supplied

Computed tomography of hepatic morphologic changes in cirrhosis of the liver.

Computed tomography of 75 biopsy proven cirrhotic patients was analyzed volumetrically and compared with CT on 50 normal subjects in an attempt to quantitate hepatic morphologic changes specific for cirrhosis. Our data show that the mean percentage of the total liver volume occupied by the right hepatic lobe decreased by 15.2% (p less than 0.0001) and the mean percentage of the total liver volume occupied by the medial segment of the left lobe decreased in volume by 10.9% (p less than 0.09) when compared with normals. Concomitantly, the mean percentage of the total liver volume occupied by the caudate lobe increased by 192% (p less than 0.0001) and the mean percentage of the total liver volume occupied by the lateral segment of the left lobe increased by 55.6% (p less than 0.0001). This increase in the volume of the lateral segment of the left lobe and decrease in the volume of the medial segment of the left lobe have not been described previously. The cirrhotic patients were divided according to etiology of their disease: alcoholic or nonalcoholic. No statistically significant difference was found in the morphologic changes based on etiology when the data were examined using analysis of variants.

Adolescent↗
PubMed1995

Computer simulations of morphologically reconstructed CA3 hippocampal neurons.

1. We tested several hypotheses with respect to the mechanisms and processes that control the firing characteristics and determine the spatial and temporal dynamics of intracellular Ca2+ in CA3 hippocampal neurons. In particular, we were interested to know 1) whether bursting and nonbursting behavior of CA3 neurons could be accounted for in a morphologically realistic model using a number of the known ionic conductances; 2) whether such a model is robust across different cell morphologies; 3) whether some particular nonuniform distribution of Ca2+ channels is required for bursting; and 4) whether such a model can reproduce the magnitude and spatial distribution of intracellular Ca2+ transients determined from fluorescence imaging studies and can predict reasonable intracellular Ca2+ concentration ([Ca2+]i) distribution for CA3 neurons. 2. For this purpose we have developed a highly detailed model of the distribution and densities of membrane ion channels in hippocampal CA3 bursting and nonbursting pyramidal neurons. This model reproduces both the experimentally observed firing modes and the dynamics of intracellular Ca2+. 3. The kinetics of the membrane ionic conductances are based on available experimental data. This model incorporates a single Na+ channel, three Ca2+ channels (CaN, CaL, and CaT), three Ca(2+)-independent K+ channels (KDR, KA, and KM), two Ca(2+)-dependent K+ channels (KC and KAHP), and intracellular Ca(2+)-related processes such as buffering, pumping, and radial diffusion. 4. To test the robustness of the model, we applied it to six different morphologically accurate reconstructions of CA3 hippocampal pyramidal neurons. In every neuron, Ca2+ channels, Ca(2+)-related processes, and Ca(2+)-dependent K+ channels were uniformly distributed over the entire cell. Ca(2+)-independent K+ channels were placed on the soma and the proximal apical dendrites. For each reconstructed cell we were able to reproduce bursting and nonbursting firing characteristics as well as Ca2+ transients and distributions for both somatic and synaptic stimulations. 5. Our simulation results suggest that CA3 pyramidal cell bursting behavior does not require any special distribution of Ca(2+)-dependent channels and mechanisms. Furthermore, a simple increase in the Ca(2+)-independent K+ conductances is sufficient to change the firing mode of our CA3 neurons from bursting to nonbursting. 6. The model also displays [Ca2+]i transients and distributions that are consistent with fluorescent imaging data. Peak [Ca2+]i distribution for synaptic stimulation of the nonbursting model is broader when compared with somatic stimulation. Somatic stimulation of the bursting model shows a broader distribution in [Ca2+]i when compared with the nonbursting model.(ABSTRACT TRUNCATED AT 400 WORDS)

Calcium↗
PubMed2000

Effect of cetrorelix on sperm morphology during migration through the epididymis in the cynomolgus macaque (Macaca fascicularis).

The importance of the cynomolgus monkey as a model for human reproductive medicine prompted this examination of epididymal sperm morphology. Computer-aided sperm morphological analysis was used for the first time to provide morphometric data on sperm heads as they traversed the epididymal duct of Macaca fascicularis. The duct was divided into six regions, starting close to the testis (proximal) and ending close to the vas deferens (distal). To determine the androgen-dependence of the changes, one group of animals received a GnRH-antagonist (Cetrorelix, Asta Medica, Frankfurt, Germany) to induce testicular regression and lower epididymal androgens, while a control group received only vehicle. Epididymides were removed 16 and 25 days after treatment, and sperm heads were analysed by a computer-assisted morphometric analyser. Cluster analysis revealed swollen sperm head cells in proximal regions 1 and 2 of the epididymis, but fewer such forms distally. Normal head shapes became the majority in region 4 and these underwent a gradual but statistically significant decrease in size (area, perimeter, length, width) and shape as they reached the distal regions. In the animals given Cetrorelix, sperm with swollen heads were found more distally than in the controls, although they were also never present in the distal cauda (region 6). Normal heads still became predominant in region 4 after 16 days treatment, and in region 6 after 25 days. The normal forms in the cauda epididymidis of treated animals were significantly larger than cells from control animals. We conclude that epididymal sperm maturation in the monkey is characterised by both a loss of sensitivity to distortion on air-drying, and by a decrease in sperm head size. The former, but not the latter, is attained by sperm in androgen-deficient epididymides from GnRH-antagonist-treated monkeys.

Animals↗