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At least 1,675 records · Page 93Linked to original sources
PubMed2001

Hypoxia-inducible factor-1alpha is an intrinsic marker for hypoxia in cervical cancer xenografts.

The hypoxia-inducible factor 1 (HIF-1) is known to induce the expression of several proteins linked to the maintenance of oxygen homeostasis, cellular energy metabolism, and tumor progression. Its alpha subunit (HIF-1alpha) is stabilized under hypoxic conditions and, therefore, might represent an intrinsic marker for tissue hypoxia. Here we report on the spatial relationship between HIF-1alpha and the nitroimidazole hypoxia marker EF5 in cervical carcinoma xenografts, and on their spatial relationship to tumor blood vessels. EF5 was administered to mice bearing ME180 and SiHa cervical cancer xenografts. Frozen tumor tissue sections, triple-stained for HIF-1alpha, the endothelial cell marker CD31, and EF5, were imaged using wide-field multiparameter immunofluorescence microscopy. Expression levels of EF5 and HIF-1alpha were similar in ME180 xenografts, but the percentage of tumor area stained with EF5 was significantly smaller than the percentage of HIF-1alpha-positive area in SiHa tumors. In both tumor types the EF5-HIF-1alpha overlap was statistically significant, thus confirming their spatial and temporal colocalization. Spatial distribution analysis of EF5 and HIF-1alpha is consistent with different pO2 value "thresholds" for EF5 binding and HIF-1alpha expression. Summarized, our results indicate that HIF-1alpha is a useful intrinsic marker for hypoxia in cervical carcinoma xenografts.

Animals↗
PubMed2001

[Morphological analysis of the formation of cluster organization of neurons, forming the corticocortical connections in the cat visual cortex in early postnatal ontogenesis].

The development of cluster organization of neurons forming direct interzonal associative projections from striate cortex (area 17) to extrastriate area 21a in cat was studied by a technique of horseradish peroxidase retrograde transport. Reconstruction of cortical region containing retrogradely labeled neurons was performed using continuous serial sections of the brain. The analysis of spatial organization was done and quantitative characteristics of distribution pattern of initial corticocortical neurons in striate cortex in kittens were obtained. Interzonal connections were detected since 14th postnatal day. Neuronal cluster organization started forming after day 21 while its pattern became similar to that in the adult animal both qualitatively and quantitatively by the end of the 2nd postnatal month, that is somewhat later than it was previously thought. The data obtained also demonstrate the age-dependent decrease in the convergence of the striate cortex projections to area 21a associated with the reduction of the area, occupied by initial neurons.

Animals↗
PubMed1974

[An attempt at estimating the mechanism of migration in Poland].

"The mechanism of migration is considered on the basis of a hypothesis postulating the existence of connection between the size of migration inflow streams and those of commutation.... High statistical reliability of this connection was treated as the basis for analyzing the influence distance exerts on the size of permanent migrations and commutation." A spatial correlation analysis is made for 108 regions in Poland (SUMMARY IN ENG)

Behavior↗
PubMed2003

Imaging small animals with positron emission tomography.

During the past few years many research centers have successfully applied their knowledge of positron emission tomography (PET) to construct PET scanners which are dedicated to image small animals such as rats and mice. Although there are many in-house built systems which are used in laboratory environments, only a few of them are commercially available at this time. This review will give an overview of dedicated animal PET systems with their technical description and main physical characteristics. Graphical analysis of spatial resolution against absolute sensitivity allows a comparison of the most important characteristics of each camera. The quadHIDAC, a PET scanner recently installed at the Department of Nuclear Medicine, University Hospital Münster, acquires images with sub-millimeter spatial resolution. A (18)F-FDG whole body image of a mouse with small structures like the left ventricle of the heart clearly visualized, demonstrates its excellent spatial resolution.

Animals↗
PubMed2003

[Optical-geometrical parameters and perception threshold of the fragmented contour figures].

The thresholds of recognition of line drawings of common objects were measured using the Gollin-test procedure, in which separate random line fragments are displayed cumulatively up to the point of recognition. It was shown that the mean percentage of contour displayed at threshold recognition for different images was always about 12.5%, despite inter-subject variability between 5% and 25%. The comparative and spatial-frequency analysis of the geometrical parameters of images was carried out for different levels of fragmentation (before threshold, at threshold, and for the complete contour). The magnitude information of the Fourier domain image of figures was characterized by maximum at low and high levels of fragmentation, but at recognition threshold fragmentation it was characterized by minimum variability.

Adolescent↗
PubMedDate not supplied

Differences in the density and spatial distribution of florid and diffuse plaques in variant Creutzfeldt-Jakob disease (vCJD).

OBJECTIVE: To determine whether in cases of variant Creutzfeldt-Jakob disease (vCJD), the florid-type plaques are derived from the diffuse plaques or whether the 2 plaque types develop independently. MATERIAL: Blocks of frontal, parietal, occipital and temporal neocortex and cerebellar cortex from 11 cases of vCJD. METHOD: The density, distribution and spatial pattern of the florid and diffuse plaques were determined in each brain region using spatial pattern analysis. RESULTS: The density of the diffuse plaques was significantly greater than that of the florid plaques in most areas. The ratio of the diffuse to florid plaques varied between brain regions and was maximal in the molecular layer of the cerebellum. The densities of the florid and diffuse plaques were positively correlated in the parietal cortex, occipital cortex, the inferior temporal gyrus and the dentate gyrus. Plaque densities were not related to disease duration. In the cerebral cortex, the diffuse plaques were more commonly evenly distributed or occurred in large clusters along the cortex parallel to the pia mater compared with the florid plaques which occurred more frequently in regularly distributed clusters. CONCLUSION: The florid plaques may not be derived from the diffuse plaques, the 2 plaque types appearing to develop independently with unique factors involved in their pathogenesis.

Adolescent↗
PubMed2004

[Distributed modeling of nutrient transport in basin with support of remote sensing and geography information system].

Agricultural non-point source pollution has become serious in our country. Modeling the processes of nutrient(especially nitrogen and phosphorus) transport in basin and evaluating the adopted management practices are important for controlling the impact of non-point pollution on environment. A research scheme for distributed simulation of nutrient transport processes in Lianshui Basin, Xingguo County, Jiangxi Province was designed, with the support of remote sensing (RS) and geography information system (GIS). The research procedure included model selection, discretization and spatial parameterization of the basin, prediction, and validation. SWAT model was selected, and basin-subbasin-hydrological response unit discretization scheme was designed. Supported by RS and GIS and based on the topographic features of the watershed, the subwatershed discretization divided the watershed into subbasins, and each subbasin could be further partitioned into multiple hydrologic response units (HRUs), which were unique soil/land use combinations within the subbasin and modeled through statistical spatial overlay analysis. The parameters of land use were obtained from the supervised classification of TM imagery based on field training samples, and those of soil were obtained from field sampling and further interpolated through geostatistical method. The simulation was carried out by using the data from 1991 to 2000. The results showed that the simulation accuracy of annual runoff water yield and sediment yield was 89.9% and 70.2%, respectively.

Computer Simulation↗
PubMed2004

Automatic localization of epileptic zones using magnetoencephalography.

Conventional visual identification of epileptic spike is a challenging problem in the clinical application of magnetoencephalography (MEG). More importantly, the conventional method has problems of detecting other abnormalities such as high frequency oscillation in the human epileptic brain. The objective of this study was to develop a new approach using magnetic spectral analysis and spatial filtering. Twelve patients with seizure have been studied with a whole cortex MEG system. Fifteen epochs were recorded for each patient; each epoch was 120 seconds. Neuromagnetic spectrum was analyzed using a new method called accumulated spectrogram. Focal increases of spectral power were localized using synthetic aperture magnetometry (SAM). The MEG results were then compared with clinical findings. Focal increases of spectral power have been identified in all patients (12/12, 100%). The locations of the focal increases of spectral power were in agreement with dipole locations of spikes in 9 patients (9/12, 75%). A comparison between MEG results and clinical findings indicated that SAM revealed focal epileptic activities in two patients when dipole fitting failed. The results suggest that epileptic regions could be quantitatively identified and accurately localized using accumulated spectrogram and SAM. In comparison to visual identification of spike, the new approach is objective and sensitive, and provides the possibility of analyzing much wider frequency bands.

Adolescent↗
PubMed2003

Analysis of hematopoietic microenvironment containing spatial development of stromal cells in nonwoven fabrics.

We previously reported that a 3D coculture system for hematopoietic cells with spatial development of stromal cells in nonwoven fabrics was superior to a conventional 2D coculture system with respect to progenitor expansion and stem cell maintenance. The hematopoietic environments in 2D and 3D coculture systems were compared and it was found there were no differences in the amounts of soluble factors, e.g., mRNA levels of stem cell factor (SCF) and thrombopoietin (TPO), the secretion of SCF, and hematopoietic stimulating activity of culture supernatant. On the other hand, the total amount of insoluble factors such as extracellular proteins around the stromal cells and the mRNA level of laminin alpha5 were apparently higher in the 3D culture.

Journal Article↗
PubMed2005

[Spatial-temporal dynamics of landscape fragmentation in North Shannxi Loess Plateau].

The study of landscape fragmentation is an important means to reveal regional ecological processes. By using the remote sensing data of 1987, 1997 and 2002, and the GIS tools, some representative quantitative indices of the landscape spatial structure and landscape fragmentation in North Shannxi Loess Plateau were calculated, aimed to investigate the relationships between landscape ecological structure and landscape pattern in this area. The results showed that cropland contributed most to the extent of landscape fragmentation, but unused land lacked obvious relationship with it. To get large-area images accurately and promptly is very important for monitoring ecological process in regional scale. Moderate-Resolution Imaging Spectroradiometer (MODIS) images in 2003 were used to derive monthly landscape fragmentation information calculated with Local Index of Spatial Associations (LISA) based on Spatial Statistical Analysis (SSA). The analysis of the fragmented landscape types showed that human disturbance had a main contribution to the seasonal landscape fragmentation. Furthermore, with the increasing percentages of cropland and unused land, landscape became more fragmented, while forestland coverage had inverse effects on the fragmentation.

China↗
PubMedDate not supplied

[Gender differences in chronic alcoholism: EEG analysis].

Comparative analysis of spatial organization of cortical biopotentials of men (n = 120) and women (n = 75) suffering from alcoholism and persons without addiction to alcohol (control groups) was carried out. Gender differences in the EEG spatial parameters under study (linear spatial synchronization in the brain cortex, non-linear spatial disorder, EEG coherence, and spectral power) were shown to be markedly less pronounced between the control groups (68 women and 85 men) than between the alcohol addicts. The obtained data allow us to explain the known fact of more serious and "malignant" character of alcoholism in women than in men in terms of neurophysiology. In alcoholics, the synchronization of low-frequency oscillations (delta and theta) was higher, whereas the synchronization of the higher-frequency spectrum part (beta1 and beta2) was lower in women than in men. This fact can be a neurophysiological basis of more progredient inhibitory-degenerative processes in women.

Alcoholism↗
PubMed1988

[Modifications in the contraction and relaxation of the left ventricle in chronic ischemic cardiopathies. Study using equilibrium angio-scintigraphy].

Our purpose was to confirm that abnormalities of left ventricular filling, which are associated with abnormalities of contraction, play an important part in the genesis of cardiac failure in chronic ischaemic heart disease. We used equilibrium radionuclide angiography of the cardiac cavities to study the behaviour of the left ventricle during contraction and relaxation in three groups of patients: a control group of 15 patients without cardiac disease (G2), and a group of 28 patients with chronic ischaemic heart disease complicated by cardiac failure (G3). From the overall activity-time curves and their first derivatives were calculated the ejection fraction, the peak ejection rate and the peak filling rate, as well as the time in the cardiac cycle when these appeared, the reference point in time being the end-diastole. Separately, an analysis of spatial distribution, pixel by pixel, of the elementary values of these times was developed with the help of new functional images constructed, pixel by pixel, from the first derivatives of the activity-time curves. These functional images were exploited by calculating histograms of times, and the width of the bars at mid-height was taken as the dispersion parameter expressed as a percentage of the cardiac cycle. There was a significant reduction of ejection fraction in groups G2 (49.8 +/- 11.6 p. 100) and G3 (36.3 +/- 15.4 p. 100) as compared to control group G1 (60.3 +/- 8.4 p. 100) (G1-G2 p less than 0.05; G2-G3 p less than 0.001; G1-G3 p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Migration distances: an international comparison.

Comparing the level or amount of migration within different countries has been a longstanding problem because the local administrative areas commonly used as the basis for measuring migration vary greatly in size and significance within and between countries. Distance moved is a critical aspect of most concepts of migration, and measuring it would facilitate cross-national comparisons. Apparently only the United States, Great Britain, and Sweden have measured migration distances for the country as a whole, and this information is used as the basis for comparative analysis of spatial mobility.

Adolescent↗
PubMed1986

Neural dynamics of speech and language coding: developmental programs, perceptual grouping, and competition for short-term memory.

A computational theory of how an observer parses a speech stream into context-sensitive language representations is described. It is shown how temporal lists of events can be chunked into unitized representations, how perceptual groupings of past item sublists can be reorganized due to information carried by newly occurring items, and how item information and temporal order information are bound together into context-sensitive codes. These language units are emergent properties due to intercellular interactions among large numbers of nerve cells. The controlling neural networks can arise through simple rules of neuronal development: random growth of connections along spatial gradients, activity-dependent self-similar cell growth, and competition for conserved synaptic sites. Within these networks, a spatial frequency analysis of temporally evolving activity patterns leads to competitive masking of inappropriate list encodings in short term memory. The neurons obey membrane equations undergoing shunting recurrent on-center off-surround interactions. Several design principles are embodied by the networks, such as the sequence masking principle, the long-term memory invariance principle, and the principle of self-similar growth.

Auditory Pathways↗