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At least 937 records · Page 52Linked to original sources
PubMed1983

[3-dimensional approach to spinal deformities. Application to the study of the prognosis of pediatric scoliosis].

The authors have utilized a computer for a spatial analysis of deformities of the spine using antero-posterior and lateral radiographs. The posterior limits of the sacral plateau and the centre of each vertebral plateau was demarcated on the antero-posterior radiograph. The posterior margin of each vertebra was demarcated on the lateral radiograph. With this information, the computer can make a picture as if the spine were seen from above and vertebral rotation can be assessed. The vertebrae are of different colours according to their level. Thirty cases have been studied and six types of infantile scoliosis defined - scoliosis with a localised hyper-rotation like a hairpin, scoliosis with rotary dislocation at the junction of two rotational levels, infantile scoliosis with a moderate curve, progressive scoliosis, benign scoliosis and spontaneously regressive scoliosis of the newborn. This study was shown that prognostic features were in accordance with classical assessments.

Child↗
PubMed1982

[Compensatory processes after unilateral cutting of the brachia of the posterior colliculi in cats].

The ability for spatial analysis of stimuli of various sensory modalities was studied in cats with a unilateral section of the brachia of the posterior colliculi. To study the possible mechanisms of compensation of localization function in different periods following the brachia section, cortical evoked potentials to sound and light were recorded, and various areas of the neocortex removed (the temporal, parietal or sensorimotor). It was suggested that after a unilateral section of the brachia, compensation of localization of non-acoustic stimuli is linked with the recovery of interhemispheric functional symmetry within the corresponding analyser systems; localization of sound stimuli is restored primarily due to activation of the temporal neocortex in the intact hemisphere, i.e. involvement of one-hemisphere binaural mechanism.

Acoustic Stimulation↗
PubMed1994

[The role of the dopamine-reactive systems of the cortex and neostriatum in organizing situational conditioned reflexes].

The nigrostriatal dopamine-reactive (DA) system was shown to participate more in spatial analysis of conditioned signals, whereas the mesocortical DA system was rather more involved in the analysis of the signals' biological significance in dogs. The DA system of the caudate nucleus was involved in realisation of cognitive programs rather, whereas the putamen's DA system--in realisation of the motor ones. The coordinated activity of different levels of the DA system seems to be necessary for organization of the goal-directed behaviour.

Acoustic Stimulation↗
PubMed1995

New geographical approaches to control of some parasitic zoonoses.

The advent of new technology for geographical representation and spatial analysis of databases from different sectors offers a new approach to planning and managing the control of tropical diseases. This article reviews the geographical and intersectoral aspects of the epidemiology and control of African trypanosomiasis, cutaneous and visceral leishmaniasis, Chagas disease, schistosomiasis, and foodborne trematode infections. The focal nature of their transmission, increasing recognition of the importance of animal reservoirs, and the need to understand environmental factors influencing their distribution are common to all these diseases. Geographical information systems (GIS) open a completely new perspective for intersectoral collaboration in adapting new technology to promote control of these diseases.

Chagas Disease↗
PubMedDate not supplied

The therapy by ischemic stress induces a durable EEG synchronization in alpha frequency band.

The effect of forearm or calf ischemia on computerized EEG was studied in five patients with peripheral nervous system affections and five patients with cerebral infarction. Spatial analysis of power spectra in various frequency bands was performed in two 8-sec epochs, the former before ischemia and the latter after 5-min from the cessation of circulatory arrest which lasted 15 min. Transient peripheral ischemia resulted in consistent augmentation of alpha activity involving both the anterior and the posterior hemispheric areas, bilaterally. On the other hand, the slower frequency bands (theta, delta) underwent minor, nonsignificant alterations after ischemic stress. The rise of alpha amplitude induced by ischemic stress was ascribed to the activation of nonspecific thalamic system. The activation of this system might also be involved in the favourable effects exerted by ischemic stress on motor recovery of paretic limbs.

Adult↗
PubMed1996

Temporal and spatial distribution of anopheline mosquitos in an Ethiopian village: implications for malaria control strategies.

The spatial and temporal distribution of Anopheles gambiae mosquitos in houses in the village of Sille in Ethiopia was monitored in 1990-91. Monthly mosquito densities in over 300 houses were obtained, and the data for each month were plotted on maps, which indicated clustering of mosquitos within the village. Spatial analysis using "kriging" techniques demonstrated clustering towards the edges of the village, the pattern of which changed with time. For example, the low density of mosquitos in one area in September increased as the nearby irrigation canals dried up during the following months. Since most entomological activity occurred at the periphery of the village, focal spraying of these areas could be a cost-effective procedure. If such clustering occurs in other villages, selective control of breeding sites and indoor spraying could provide a more efficient use of limited resources than traditional total coverage.

Animals↗
PubMed1996

[Social networks and diffusion of AIDS in Brazil].

The HIV/AIDS epidemic has been simplistically interpreted as a phenomenon restricted to risk groups that are socially and spatially circumscribed. However, epidemic trends in recent years have demonstrated the need to employ open diffusion models that emphasize social interaction as a means of spread of HIV. This study is a spatial analysis of the AIDS epidemic in Brazil, which sought to incorporate variables reflecting economic and demographic events into a system for processing geographically referenced health information. Findings indicate that metropolises and regional urban centers, mainly those in the Southeast, play an important role in the spread of the epidemic, not only because of their population density but also because they are centers of trade and social interaction. In smaller cities located in the state of São Paulo, a large number of AIDS cases among injecting drug users are concentrated, revealing the routes and centers of cocaine use.

Acquired Immunodeficiency Syndrome↗
PubMed1997

S phase determination in intact colonic crypts by histone H3 messenger RNA in situ hybridization and confocal microscopy.

Proliferating cells have a restricted three-dimensional spatial distribution within the crypt, which is the proliferative unit of the colon. Accurate quantitative and spatial analyses of S phase cells in the colon have therefore been limited by histological techniques. To overcome these limitations, S phase cells in microdissected intact colonic crypts of control, modified-starved, and refed rats were labeled by histone H3 in situ hybridization and analyzed by confocal microscopy. High-resolution digital images of the crypt cell nuclei stained with cyanine nucleic acid and of the labeled S phase cells were produced from confocal microscopic optical crypt sections. The S phase labeling index (LI) per whole crypt significantly (P < 0.001) discriminated the proliferative differences between control, modified-starved, and refed rats and correlated (r = 0.92) with the LI determined from histological crypt sections of the same rats. The variance component of the LI attributable to differences between whole crypts, 0.44 (95% confidence interval, 0.38-0.51), was considerably smaller than that attributable to differences between histological crypt sections, 6.07 (95% confidence interval, 5.18-6.96). Confocal microscopy and histone H3 in situ hybridization of intact three-dimensional crypts enables precise in vitro quantitation and spatial analysis of the total and S phase crypt cells.

Animals↗
PubMed1997

Health impacts of large releases of radionuclides. The radioecological significance of semi-natural ecosystems.

The transfer of radiocaesium to many food products either produced in or harvested from semi-natural ecosystems is high compared with intensive agricultural areas. Radiocaesium contamination levels in semi-natural foods are highly variable and difficult to predict. Spatial analysis may help to explain some of the variability and give improved estimates of the total output of radiocaesium in food products produced or harvested from semi-natural ecosystems. Consumption of foodstuffs from semi-natural ecosystems can contribute significantly to radiocaesium ingestion by humans. The long effective half-lives that occur for some semi-natural products lead to an increase with time in their importance compared with agricultural products. In determining the importance of semi-natural food products, the diet needs to be considered for both the average population and for special groups who utilize these environments to a greater extent than normal. Effective countermeasures have been developed to reduce radiocaesium levels in some semi-natural products.

Agriculture↗
PubMedDate not supplied

The effect of head-to-trunk position on the direction of arm movements before, during, and after space flight.

This contribution deals with the examination of the consequences of different head-to-trunk positions on arm movements under normal gravity and during prolonged space flight. One of the objectives of this study was to investigate the influence of weightlessness on the condition of the spatial analysis system. Aimed arm movements in the horizontal plane (pointings towards two visual targets) were recorded, first with eyes open, head straight (learning part), then with eyes closed, head straight and during yaw or roll position of the head (performance part). Measurements related to these different head-to-trunk-positions were taken in one short-term and nine long-term cosmonauts preflight, inflight, and postflight. Terrestrial control experiments were carried out with an extended experimental design in 14 healthy volunteers. The analysis of these experiments revealed that, with eyes closed and the head in yaw position, cosmonauts before flight and control subjects exhibit significant slants of the movement plane of the arm. Contrary to terrestrial measurements, in space experiments roll tilt of the head to the right is correlated with considerable counterclockwise slant of the movement plane. This slant of the movement plane of the arm was interpreted as tilt of the internal representation of the horizontal coordinate. The effect is larger with greater distortion induced by the changed head position and with larger muscular involvement to keep this position. This effect is also increased by the reduction of information (for example, in microgravity). The amount and the direction of the horizontal offset of the arm movements are shown to be dependent on the head-to-trunk position, too. Additionally, we have found changes in the amplitude and in the duration of the arm movement, in the vertical offset, and in the curvature of the movement paths, depending on the experimental conditions.

Adult↗
PubMed1982

Application of the optical Fourier transform for analysis of the spatial distribution of collagen fibers in normal and osteopetrotic bone tissue.

Optical Fourier analysis was applied for evaluation of the differences between normal and pathologically changed bone tissue. Collagen fibers were used as markers of bone structure. To prove the usefulness of this technique for objective mathematical analysis of these differences the spatial spatial distribution of collagen fiber bundles was evaluated in normal and osteopetrotic bone. The variation in the spatial distribution of collagen fiber bundles in cross sections of femur diaphyses was evaluated quantitatively by optical diffraction three groups of Fatty Orl-op strain rats, i.e. phenotypically normal animals, osteopetrotic (op/op) mutants and op/op-mutants cured by transplantation of normal syngenic bone marrow. The histological sections of decalcified bone were stained with Sirus-Red and then photographed under polarizing microscope. The Sirus-Red staining was used to enhance the natural birefringency of collagen fibers. Diffractograms obtained from microphotographs of selected bone section areas, i.e. outer and inner circumferential lamellae and haversian bone of normal and cured op/op animals as well as whole cortical bone and woven bone filling the medullary cavities in op/op mutants were analysed separately. Diffractograms contain summarized information on the size and relative position of these structures in histological sections. The radial and angular distribution of light energy were evaluated for each diffractogram with an electronic detector. The obtained distributions were described by several sets of parameters concerning the position, level and shape of local maxima and minima. Out of these parameters five with the highest discriminant power were chosen for further mathematical analysis. This analysis was based on the calculation of the position of centroids in the multidimensional space described by the linear functions of the chosen parameters for each of the evaluated bone section areas. The centroids (mean values of discriminant scores of each group) represent the centers of gravity of the analysed groups, while the separation of the centroids tested by the F-test illustrates the differences between the respective groups of selected bone section areas. A high level of separation of centroids was found when osteopetreotic bone was compared with normal one, what means that the spatial distribution, size and interstructural distances between the collagen fiber bundles in bone tissue in these two groups of animals differ markedly. A similar situation was observed when osteopetrotic bone was compared with bone tissue obtained from op/op mutants cured by transplantation of normal syngenic bone marrow. On the other hand, the level of separation of centroids was low when bone tissue of cured op/op mutants was compared with the control one, a finding which corresponds to the less pronounced histological differences between these two groups of animals. Computer-aided classification on single microphotographs of selected bone section areas to the known a priori type of bone tissue was performed...

Animals↗
PubMed1989

Segregation and overlap of callosal and association neurons in frontal and parietal cortices of primates: a spectral and coherency analysis.

The spatial relations between selected classes of association and callosal neurons were studied in the frontal and parietal lobes of the macaque monkey using retrogradely transported fluorescent dyes. Fast blue and nuclear yellow were injected in the left frontal (areas 4 and 6) and right posterior parietal (area 5) cortices, respectively. These injections led to the retrograde labeling, in the right frontal cortex, of callosal neurons projecting homotopically and association neurons projecting to ipsilateral area 5; in the left superior parietal lobule, of callosal neurons projecting to contralateral area 5 and association neurons projecting to the ipsilateral frontal lobe. In both frontal and parietal cortices, callosal and association neurons were located in layers III and V-VI; a few neurons were also found in layer II. The contribution of layers V-VI to the callosum was significantly higher in areas 4 and 6 than in area 5. Only a small number of neurons (less than 1%) were double labeled. Spectral analyses were used to characterize the spatial periodicities of the distributions of callosal and association neurons. In areas 4, 6, and 5, both association and callosal spectra were dominated by a strong elevation in the range of low spatial frequencies, corresponding to periodicities in cell density with a peak-to-peak distance of about 8 mm. This indicated an arrangement of these corticocortical cells in the form of bands. The latter displayed various shapes and orientations and were composed of more discrete assemblies of cell clusters of about 400-1000 microns width. Their presence was revealed in the power spectra by a small elevation in the range of high spatial frequencies. The coherency analysis assessed the degree of linear relationships for each spatial frequency, and therefore the degree of similarity, between callosal and association cell distributions, together with their phase relations. Little coherency was found in areas 4 and 6 between bands of callosal and association neurons, which suggests that the 2 cell populations are differently and independently distributed in the tangential domain, with no simple phase relations. The overall mean coherency was higher in area 5 than in the frontal cortex: callosal and association bands were more similar in shape, with more extensive zones of overlap. These data indicate that callosal and association neurons share common principles of spatial organization despite the great regional variability of their interrelations in the tangential cortical domain.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1997

Perception of stationary plaids: the role of spatial filters in edge analysis.

Orientation-tuned spatial filters in visual cortex are widely held to act as "orientation detectors", but our experiments on the perception of stationary two-dimensional (2-D) plaids require a new view. When two sinusoidal gratings at different orientations (say 1 c/deg, +/- 45 deg from vertical) are superimposed to form a standard plaid they do not, in general, look like two sets of oblique contours (diamonds) but more like a blurred checkerboard (squares) with vertical and horizontal edges, although the Fourier components are oblique. The pattern of edges seen in this plaid and others corresponds to the zero-crossings (ZCs) in the output of a circular filter, but adaptation and masking experiments suggest that oriented filters are being summed to emulate circular filtering, before ZC analysis. At low contrasts or after adaptation to an intermediate orientation, the combining of filters can fail or be "broken", and the diamond structure of the components is seen instead. Adding a low contrast third harmonic to one component in square-wave phase also changed the plaid's appearance from squares to diamonds, but adapting to the third harmonic enhanced the square appearance. Filters can evidently switch from combining across orientation to combining across spatial frequency. The combination stage of edge detection may involve variably weighted summing of oriented filters in monocular pathways, followed by a process that makes explicit the locations and orientations of features.

Adaptation, Ocular↗
PubMed2000

Assessment of mitochondrial polarization status in living cells based on analysis of the spatial heterogeneity of rhodamine 123 fluorescence staining.

The mitochondrial membrane potential (psimito) is an important parameter not only of mitochondrial but also of cellular status. Prolonged mitochondrial depolarization is associated with various forms of neuronal death. Assessment of mitochondrial depolarization can take advantage of the specific properties of the lipophilic dyes that distribute in a potentiometrically determined ratio across membranes. Using conventional imaging, we showed that rhodamine 123 accumulated in the mitochondria, generating a highly heterogeneous pattern of spatial distribution of fluorescence across the cell body. Collapse of the psimito following exposure to a protonophore, carbonylcyanide p-chloromethoxyphenylhydrazone (CCCP), released rhodamine 123 from mitochondria into the cytosol. Under acutely changed conditions, this increased the overall intensity of the fluorescence signal and significantly decreased the degree of spatial heterogeneity of the signal. If mitochondrial depolarization was sustained chronically, the intensity of the signal decreased, but the increase in the spatial homogeneity of the fluorescent signal was maintained. Image analysis showed that the level of spatial heterogeneity of the signal can be assessed by calculating, for each individual neurone, the spread of pixel intensities values around the mean. This spread is defined by the coefficient of variation (CV), which is a measure of the standard deviation normalized to the average, and was inversely related to mitochondrial depolarization measured under different conditions. Thus, the degree of spatial heterogeneity of the rhodamine 123 signal measured from a neurone is a reliable indicator for the assessment of mitochondrial depolarization and can be used in experiments to monitor psimito over shorter or longer periods.

Animals↗
PubMed2006

Tract-based spatial statistics: voxelwise analysis of multi-subject diffusion data.

There has been much recent interest in using magnetic resonance diffusion imaging to provide information about anatomical connectivity in the brain, by measuring the anisotropic diffusion of water in white matter tracts. One of the measures most commonly derived from diffusion data is fractional anisotropy (FA), which quantifies how strongly directional the local tract structure is. Many imaging studies are starting to use FA images in voxelwise statistical analyses, in order to localise brain changes related to development, degeneration and disease. However, optimal analysis is compromised by the use of standard registration algorithms; there has not to date been a satisfactory solution to the question of how to align FA images from multiple subjects in a way that allows for valid conclusions to be drawn from the subsequent voxelwise analysis. Furthermore, the arbitrariness of the choice of spatial smoothing extent has not yet been resolved. In this paper, we present a new method that aims to solve these issues via (a) carefully tuned non-linear registration, followed by (b) projection onto an alignment-invariant tract representation (the "mean FA skeleton"). We refer to this new approach as Tract-Based Spatial Statistics (TBSS). TBSS aims to improve the sensitivity, objectivity and interpretability of analysis of multi-subject diffusion imaging studies. We describe TBSS in detail and present example TBSS results from several diffusion imaging studies.

Amyotrophic Lateral Sclerosis↗
PubMed2026

transFusion: a novel comprehensive platform for integration analysis of single-cell and spatial transcriptomics.

MOTIVATION: Understanding spatial organization, intercellular interactions, and regulatory networks within the spatial context of tissues is crucial for uncovering complex biological processes and disease mechanisms. Spatial transcriptomics technologies have revolutionized this field by enabling the spatially resolved profiling of gene expression. 10&#xd7; Visium has emerged as the predominant spatial technology, but its low resolution and the complexity of integrating multimodal datasets present significant analytical challenges, particularly for researchers with limited computational and statistical expertise. Current spatial transcriptomics analysis platforms generally fall short of effectively integrating multimodal data and maximizing the utility of spatial information-such as uncovering complex cellular spatial dependencies, multimodal gradient patterns, and spatial coexpression of ligand-receptor pairs and regulatory networks related to disease or biological states-thereby limiting their ability to provide comprehensive end-to-end analytical workflows when analyzing 10&#xd7; Visium data. RESULTS: To address these limitations, we developed transFusion, a novel, advanced web-based platform specializing in the most comprehensive and effective integration analysis of scRNA-seq and 10&#xd7; Visium spatial transcriptomics data. transFusion offers 12 key functions, from basic visualization to advanced analyses, including intercellular dependency analysis, ligand-receptor coexpression identification and visualization, and spatial multimodal gradient variation patterns. Two case studies were used to demonstrate transFusion's capabilities in exploring tissue architecture, intercellular communication, dependency networks, and multimodal gradient variation patterns with minimal computational skills and statistical expertise. transFusion provides a flexible and powerful framework for multimodal data integration analysis. AVAILABILITY AND IMPLEMENTATION: transFusion is freely available at https://github.com/WQLin8/transFusion.

Spatial Transcriptomics↗
PubMed2006

Bayesian fMRI data analysis with sparse spatial basis function priors.

In previous work we have described a spatially regularised General Linear Model (GLM) for the analysis of brain functional Magnetic Resonance Imaging (fMRI) data where Posterior Probability Maps (PPMs) are used to characterise regionally specific effects. The spatial regularisation is defined over regression coefficients via a Laplacian kernel matrix and embodies prior knowledge that evoked responses are spatially contiguous and locally homogeneous. In this paper we propose to finesse this Bayesian framework by specifying spatial priors using Sparse Spatial Basis Functions (SSBFs). These are defined via a hierarchical probabilistic model which, when inverted, automatically selects an appropriate subset of basis functions. The method includes non-linear wavelet shrinkage as a special case. As compared to Laplacian spatial priors, SSBFs allow for spatial variations in signal smoothness, are more computationally efficient and are robust to heteroscedastic noise. Results are shown on synthetic data and on data from an event-related fMRI experiment.

Algorithms↗
PubMed2004

Household survey of dengue infection in central Brazil: spatial point pattern analysis and risk factors assessment.

Urban dengue fever is now considered a major public health threat in most American countries. A household survey was conducted in the city of Goiania in central Brazil in 2001 to assess prevalence of dengue infection and individual and area-based risk factors. Spatial point pattern analysis was performed using the dual Kernel method. A total of 1,610 households were surveyed; 1,585 individuals more than five years old had blood and data collected. Sera were tested for IgM/IgG antibodies by an enzyme-linked immunoassay. Area-based indicators derived from census data were linked to geocoded residential address. The seroprevalence of dengue was 29.5% and the estimate prevalence surface reached 50% in the outskirts areas. The risk of infection was significantly associated with older age (P < 0.01), low education (odds ratio [OR] = 3.45, 95% confidence interval [CI] = 1.82-6.55), and low income (OR = 1.32, 95% CI = 1.02-1.71) in multivariate analysis. This study highlighted the heterogeneity of dengue transmission within the city and can assist in spatial targeting control interventions.

Adolescent↗