An analysis of changes in the spatial vectorcardiogram with aging.
Explore the source record for details and available documents.
Aging↗
SEARCH · Search PubMed
Results for “spatial analysis”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Progress in computer analysis of the exercise electrocardiogram.
The potential advantages of digital computer processing of exercise electrocardiographic data include reduction of noise, compression of data, improved precision and application of optimal criteria. Most prior approaches to such processing required equipment that was both expensive and inconvenient. With the revolution in instrumentation brought about by the development of microcomputers, powerful dedicated computers can now be afforded by many exercise laboratories. There are many approaches to computerized management of exercise electrocardiographic data and various criteria for ischemia. Studies are necessary to validate computer algorithms so that these devices can be used diagnostically to best advantage. Cardiologists need some understanding of this field so that they can be discriminating users of computer systems. In addition, the results of studies correlating electrocardiographic changes with radionuclide methods of assessing myocardial perfusion and function should enable such assessments to be made from the electrocardiographic signals alone, particularly when aided by computer analysis of spatial shifts.
Angina Pectoris↗
Improved exercise performance in persons with stable angina pectoris receiving diltiazem.
The effects of diltiazem, a calcium antagonist drug, we compared with those of placebo on exercise performance during a series of symptom-limited upright exercise tests. Ten patients with chronic stable angina were studied over a period of 7 weeks. The drug was administered in a random double-blind fashion and was evaluated at increasing dose levels of 120, 180 and 240 mg/day. Diltiazem was effective in increasing the total duration of exercise (p < 0.001) and the time the first onset of angina (p < 0.02) and to the first appearance of 1 mm of S-T depression (p < 0.02). These effects were most marked at the highest dose level of diltiazem. The heart rate was reduced at rest (p < 0.05) and during submaximal exercise (p < 0.001). There was a reduction in diastolic blood pressure during submaximal exercise (p < 0.04) but no change in systolic pressure. Pressure-rate product was significantly reduced at submaximal (p < 0.001) but not maximal exercise. The reduction in pressure-rate product is postulated as the mechanism by which diltiazem enhances duration of exercise. There was no reduction in electrocardiographic evidence of myocardial ischemia at peak exercise by either clinical observation or computer analysis of spatial electrocardiographic variables Five of the six patients who continued to take the drug maintained or improved their exercise performance on follow-up study 8 to 10 months later.
Angina Pectoris↗
Influence of lateralized sensorimotor and neuropsychological activities on electroencephalographic spectral power.
In order to test the effect of 'lateralized' sensorimotor and neuropsychological activities on EEG spectral power (P), we recorded EEGs over the right and left central regions with 3 different derivations C5P3/C6P4, C5Cz/C6Cz, and C5 ears-linked (EL)/C6EL in 14 young, right-handed men who underwent ten 2 min sequences including 4 during rest (3 with eyes closed (EC), 1 with eyes open (EO], and 6 during tasks reputed to involve preferentially the left (Le) or the right (Ri) hemisphere, i.e., pure left and pure right motor activity of the hand (EC), pure neuropsychological tasks consisting in lexical followed by spatial form analysis and finally mixed (neuropsychological and motor) EC tasks consisting in writing followed by left hand object recognition. Three spectral parameters P, log P and asymmetry index AI = (P Ri-P Le)/(P Ri + P Le) were calculated in 5 frequency bands theta, alpha 1, alpha 2, alpha 3 and beta 1. We observed a relationship between task complexity and P reduction on both hemispheres which was greater during rest, less during motor activity and least during mixed motor and neuropsychological activities; during EC activities more specifically involving the left hemisphere, only the comparison between rest and mixed sequences was significant. During EC activities involving the right hemisphere, both motor and mixed sequences were significantly different from rest sequences. In addition, during the EO sequences, P was usually greater than during rest. As compared to rest conditions, the AI increased during sequences preferentially involving the left hemisphere and decreased during preferentially right hemisphere activities.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Why spatial frequency processing in the visual cortex?
The nature of redundancy in visual images is discussed and the methods of removing statistical redundancies are considered. It is demonstrated that local spatial frequency analysis is a highly successful method and it is thus argued that this determines the choice of representation of the visual image by the simple cells of the visual cortex.
Humans↗
Dissociation of local and global processing in visual agnosia.
Subsequent to strokes in the right and left inferomedial occipito-temporal lobes, two patients became prosopagnosic and alexic, respectively. They also show a complementary dissociation of the analysis of handwritten text. The patient with the right posterior stroke can read it but not recognize whose handwriting it is; the patient with the left posterior stroke cannot read the text but knows who wrote it. The analysis of spatial vision revealed that the prosopagnosic patient has no problem with seeing texture elements when presented in isolation. Yet she performs poorly with Moiré and texture perception, i.e. she suffers from a selective loss of global visual perception. The alexic patient performs well with Moiré patterns but neither with (complex) texture elements nor with textures. She seemingly can locally and globally process patterns composed of simple figural elements but fails with stimuli that require the integration of features. This finding of a concomitant dissociation of local and global visual processes in the two patients supports the view that prosopagnosia as well as alexia are the most conspicuous aspects of more general alterations of visual perception.
Agnosia↗
Schooling behavior of tadpoles: a potential indicator of ototoxicity.
Fish and tadpoles in schools use hair cells of their lateral line system to assess their position in relation to neighbors. This suggests that pharmaceutical agents that damage hair cells in the mammalian inner ear may also alter geometry in fish and tadpole schools. We used a computer-based image analysis system to examine the effect of the ototoxic aminoglycoside antibiotic, streptomycin, on school geometry for tadpoles of the African clawed frog Xenopus laevis. Tadpoles exposed to streptomycin in the surrounding water show a general tendency toward clumping, and an increase in the distance over which they orient parallel to neighbors, compared to controls. These behavioral responses appear in 18 min or less, and are evident in some tadpoles exposed to concentrations as low as 5 micrograms/ml. Results suggest that analysis of spatial relations in tadpole schools could serve as a method for rapidly detecting ototoxic potential of agents suspected of damaging hair cells.
Animals↗
The time of origin of somatostatin-immunoreactive neurons in the rat hippocampal formation.
Experiments utilizing a combination of [3H]thymidine autoradiography and immunohistochemistry were conducted to determine the time of origin of somatostatin-immunoreactive (SSIR) neurons in the hippocampal formation of the rat. A quantitative and topographic description of neurogenesis in this peptide-containing neuronal system was generated using a computer-aided system to plot the position of labeled cells. Dissected and 'flattened' hippocampal preparations were used to facilitate the analysis of spatial gradients of SSIR cell development. The results indicate that most SSIR hippocampal cells are generated during a short embryonic period which extends from the 12th through the 15th day of gestation (E12-E15). Within this period of development, the distribution of SSIR cells follows a spatial gradient along the transverse or subiculo-dentate axis of the hippocampus. The earliest formed SSIR neurons, generated on E12 and E13, are preferentially distributed to the subiculum, those generated on E14 are most commonly observed throughout the CA1-CA3 fields of the hippocampus and SSIR neurons which become postmitotic on E15 are more heavily represented in the hilar region of the dentate gyrus than cells born at other stages of development. There was no clear-cut neurogenic gradient along the septotemporal axis of the hippocampus. These results indicate that somatostatin cells in the rat hippocampal formation are generated during the same prenatal period when glutamic acid decarboxylase (GAD)-positive neurons become postmitotic. These studies also suggest that quantitative developmental analyses of chemically specific cell types can reveal prominent features of cortical ontogeny that are not readily apparent in standard [3H]thymidine preparations.
Aging↗
Philothermal response, microtubules and dementia.
The role of microtubules in the philothermal response of polymorphonuclear leukocytes (PMNs) was examined using colchicine, a known microtubule disrupting agent. Colchicine inhibited PMN migration in a dose dependent fashion. Spatial distribution analysis of the responding cell population revealed a preferential inhibition of distal cell migration, a pattern similar to that found for PMNs obtained from patients with dementia of the Alzheimer type (DAT). The result is consistent with the known role of microtubules in directed cell migration and the hypothesized microtubular defect in DAT. Further investigations of microtubules may provide insight into the etiology and pathogenesis of DAT.
Adult↗
[Geographic inequalities in mortality in Cameroon].
Because of the geographic diversity of Cameroon, the analysis of spatial inequalities of mortality is a challenging research topic. This is true for mortality and morbidity as well as for the distribution of underlying factors. Among these are the geographic (or ecological) factors. The example of the distribution of infant mortality is given here. It seems difficult to isolate geographical and socioeconomic factors which are intertwined. Anyway, taking into account the spatial variation of mortality can be a fundamental element in the implementation of health policy.
Cameroon↗
Evoked potential and visual half-field evidence for task-dependent cerebral asymmetries in congenitally deaf adults.
Twelve congenitally deaf subjects participated in a visual half-field experiment under two conditions, lexical decision and line orientation discrimination. Reaction time, accuracy, and evoked potentials from left and right temporo-parietal sites were simultaneously obtained. The evoked potential data were analyzed using a principal components analysis followed by analysis of variance and multiple regression. Both the visual half-field and the evoked potential data produced evidence of task-dependent cerebral asymmetries. Individual differences in visual half-field asymmetries in accuracy and individual scores on three cognitive paper and pencil tests were strongly predicted by linear combinations of several independent hemispheric asymmetry variables derived from evoked potential component scores. The results suggest that cerebral specialization in congenitally deaf people is a complex, multidimensional phenomenon, and provide the first evidence for a direct relationship between cerebral asymmetry and cognitive performance in this population.
Adult↗
Intraoperative EEG changes in relation to the surgical procedure during isoflurane-nitrous oxide anesthesia: hysterectomy versus mastectomy.
STUDY OBJECTIVES: To investigate topographical changes in electroencephalographic (EEG) frequencies and spectral power density in relation to different surgical procedures (abdominal hysterectomy versus mastectomy) during steady-state isoflurane-nitrous oxide (N2O) anesthesia. DESIGN: Prospective, nonrandomized, open study. SETTING: University hospital. PATIENTS: 34 ASA status I and II patients scheduled for elective abdominal hysterectomy or mastectomy. INTERVENTIONS: 12 patients were studied without surgery (Group I, control). 22 patients were studied for the first 14 minutes following skin incision during hysterectomy (Group 2, n = 11) or mastectomy (Group 3, n = 11). MEASUREMENTS AND MAIN RESULTS: Anesthesia was maintained with 0.6% isoflurane in 66% N2O in oxygen (O2). EEG was recorded via 17 channels followed by calculation of spectral power densities in selected frequency bands for each recording site. In addition, heart rate, mean arterial pressure (MAP), end-tidal carbon dioxide tensions, and isoflurane concentration were recorded. Total observation time was 20 minutes in all groups. At baseline, EEG variables were comparable in all groups. The EEG demonstrated slow wave activity superimposed with alpha waves. Start of surgery resulted in increases of slower waves and decreases in alpha activity. In both surgical groups, these EEG changes were most pronounced at frontal recording sites (p < 0.05) with differences in the frequency content. In Group 2 (hysterectomy), delta-activity became dominant, whereas in Group 3 (mastectomy), a shift to theta waves was observed. During surgery MAP was increased by 40% (Group 2; p < 0.05) and 21% (Group 3; p < 0.05), respectively. CONCLUSIONS: These results show that specific surgical procedures may induce EEG slow wave activity to a different degree. The EEG response varied in relation to the surgical procedure and/or the intensity of noxious stimulation. Mastectomy resulted in the appearance of theta activity whereas, during laparotomy, the EEG frequency content was shifted to delta waves. The topographical analysis indicates spatial inhomogeneities in the EEG responses with a dominance at frontal areas. From this findings, it may be concluded that the electrode montage used for intraoperative EEG recordings has to be carefully selected.
Adult↗
Extrinsic heterogeneity: Collectivity in isotropic conformational fluctuations of chromosomes.
Eukaryotic interphase chromosomes maintain a three-dimensional conformation within the nucleus and undergo fluctuations. However, the analysis of chromosome conformational fluctuations has been mainly limited to chromosome conformation capture data that record the contact frequencies between chromosomal regions. Herein, we investigated chromosome fluctuations as polymers based on experimental data from sequential fluorescence in situ hybridization using a multiomics methodology. To describe the principal modes of chromosome fluctuations, we applied principal-component analysis to the three-dimensional conformation information of single chromosomes in 446 mouse embryonic stem cells obtained from sequential fluorescence in situ hybridization data analysis for spatial genomics and signals of nuclear factors (histone marks, repeat DNAs, and proteins in interchromosomal nuclear compartments). We found that chromosome fluctuations exhibit both isotropic and anisotropic modes. The isotropic conformational fluctuations of all chromosome types tended to synchronize each other, reflecting extrinsic heterogeneity in chromosome conformation that is independent of the cell cycle. In contrast, anisotropic conformational fluctuations, occurring in a spindle-like shape, were associated with the interactions between repeat DNAs and nuclear factors. These results highlight the importance of dissecting cell-cycle-independent nuclear organization based on the conformational folding of chromosomes and the interactions between genomic regions and nuclear factors.
Animals↗
Dipole localization using simulated intracerebral EEG.
OBJECTIVE: In the clinical interpretation of intracerebral EEGs, epileptic foci are commonly identified by visually analyzing the amplitude of the potentials. This is potentially misleading since electrodes record activity from several sources, but the nearest ones generate large amplitudes that can overpower distant sources. Our objective was to improve foci detection in intracerebral recordings by applying source localization methods. METHODS: Data were simulated by placing 3 sources in a semi-infinite medium near 3 intracerebral electrodes. Potentials were generated and contaminated with white and correlated noise. Two inverse problem algorithms, beamforming and RAP-MUSIC, were used to calculate equivalent dipoles. RESULTS: Simulations for each noise types showed that the two methods detected the source locations accurately, with RAP-MUSIC reporting lower orientation errors. With correlated noise, beamforming reconstructed original source waveforms poorly. A spatial resolution analysis was performed, in which beamforming adequately distinguished sources separated by 1.2 cm, whereas RAP-MUSIC separated sources as close as 0.4-0.6 cm. CONCLUSIONS: Both source localization methods proved useful in detecting the location of dipolar sources based on simulated intracerebral potentials. For all simulations, RAP-MUSIC was more accurate than beamforming. SIGNIFICANCE: It is possible to use source localization methods traditionally applied to scalp recordings for improving source detection from intracerebral recordings.
Algorithms↗
An event-related fMRI study of the neural networks underlying the encoding, maintenance, and retrieval phase in a delayed-match-to-sample task.
Memory loads exceeding the limited capacity of working memory (WM) have been shown to expand the prefrontal areas that participate in WM and have revealed substantial individual differences in performance. We used a delayed-match-to-sample (DMS) task in an event-related fMRI study to map the full extent of the expanded regional activations associated with supracapacity loads. A 6-letter study array was compared to arrays of 1 and 3 letters. The task comprised separate encoding, retention, and retrieval fMRI epochs. A brain-wide spatial covariance analysis was applied to the data of all task epochs to identify patterns of correlated regional activations whose expression increased monotonically across 3 memory-load levels on a subject-by-subject basis. Such load-related activation patterns were in all task phases. Of greatest interest is the activation pattern that was obtained during the maintenance phase: increasing activation with memory load was found not only in the lateral PFC (BA 9,44) but also in the parietal lobe (BA 7,40), anterior cingulate (BA 32), and cerebellum. Decreasing activation was found in the occipito-temporal lobe (BA 19,39) as well as the medial prefrontal cortex (BA 9,10). Subject increases in pattern expression from 1 to 6 items were positively correlated with the corresponding reaction time increases (p<0.05) and negatively correlated with NARTIQ (p<0.05), indicating that people who were faster in their responses and had higher NARTIQ had to increase their subject expression of the memory-load-related activation pattern less and were more efficient at the cognitive task. Our method thus not only reproduced findings of other WM studies but also addressed the issue of interactions between lateral PFC and other parts of the brain during the task, for the retention of the to-be-remembered information. The load-related activation patterns from encoding and retrieval phase and their relationship to behavior are also discussed.
Adult↗
highSpaClone enables copy number alteration inference and tumor subclone analysis for high-resolution spatial transcriptomics.
High-resolution spatially resolved transcriptomics (SRT) offers unprecedented opportunities to investigate tumor heterogeneity but poses substantial computational and analytical challenges. Here, we present highSpaClone, a computational framework for copy number alteration (CNA) inference and tumor subclone identification from high-resolution SRT data across multiple spatial scales. By integrating spatial constraints into CNA estimation and clonal clustering, highSpaClone enables neighboring spatial locations to share information, thereby improving the robustness of genomic signals and the accuracy of subclone delineation. Across multiple Xenium and Visium HD datasets, highSpaClone revealed unique transcriptional programs, clonal evolutionary trajectories, and distinct tumor-microenvironment interactions. Furthermore, in human colorectal cancer samples, highSpaClone detected CNA events in histologically normal epithelial regions, highlighting early genomic alterations associated with field cancerization. These findings establish highSpaClone as a scalable framework for studying clonal architecture and tumor evolution.
CP: cancer biology↗
Quantifying evidence for phenotypic specificity (PP4) for syndromic phenotypes: Large-scale integration of rare germline FH variants from diagnostic laboratory testing for HLRCC and renal cancer.
PURPOSE: Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a rare cancer susceptibility syndrome exclusively attributable to pathogenic variants in FH (HGNC:3700). This article quantitatively weights the phenotypic context (PP4/PS4) of such very rare variants in FH. METHODS: We collated clinical diagnostic testing data on germline FH variants from 387 individuals with HLRCC and 1780 individuals with renal cancer and compared the frequency of "very-rare" variants in each phenotypic cohort with 562,295 population controls. We generated pan-gene very rare variant likelihood ratios (PG-VRV-LRs), domain-specific likelihood ratios for missense variants (DS-VRMV-LR) using spatial clustering analysis, and log2.08 likelihood ratios (LLRs) as applicable within the updated American College of Medical Genetics and Genomics/Association for Molecular Pathology variant classification framework. RESULTS: For HLRCC, the PG-VRV-LR was estimated to be 2669.4 (95% CI 1843.4-3881.2, LLR 10.77) for truncating variants and 214.7 (95% CI 185.0-246.9, LLR 7.33) for missense variants. For renal cancer, the PG-VRV-LR was 95.5 (95% CI 48.9-183.0, LLR 6.23) for truncating variants and 5.8 (95% CI 3.5-9.3, LLR 2.39) for missense variants. Clustering analysis in HLRCC cases revealed 3 "hotspot" regions wherein the DS-VRMV-LR increased to 1226.9. CONCLUSION: These data provide quantitative measures for very rare missense and truncating variants in FH, which reflect the differing phenotypic specificity of HLRCC and renal cancer and may be applicable in clinical variant classification.
Humans↗
Techniques for accuracy assessment of tree locations extracted from remotely sensed imagery.
Remotely sensed imagery is becoming a common source of environmental data. Consequently, there is an increasing need for tools to assess the accuracy and information content of such data. Particularly when the spatial resolution of imagery is fine, the accuracy of image processing is determined by comparisons with field data. However, the nature of error is more difficult to assess. In this paper we describe a set of tools intended for such an assessment when tree objects are extracted and field data are available for comparison. These techniques are demonstrated on individual tree locations extracted from an IKONOS image via local maximum filtering. The locations of the extracted trees are compared with field data to determine the number of found and missed trees. Aspatial and spatial (Voronoi) analysis methods are used to examine the nature of errors by searching for trends in characteristics of found and missed trees. As well, analysis is conducted to assess the information content of found trees.
Automation↗