Intersubject analysis of fMRI data using spatial normalization.
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Brain Mapping↗
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A recurrent system incorporating characteristics of the visual system: a model for the function of backward neural connections in the visual system.
A recurrent system is constructed in order to investigate the role of the backward neural connections found in the primate visual system. The system incorporates a layer to perform localized spatial frequency analysis of input images, a function which has been assumed to take place in the primary visual cortex. The function of the system is examined by simulation. The results show that the system can separate an object pattern from its background, irrespective of its precise position. The acceptable displacement range for input images is determined from the width of the window function used to calculate the local Fourier transform. A multilayer version of the above recurrent system is also constructed.
Animals↗
Pulsatile coronary flow determination by digital angiography.
A new angiographic method to calculate absolute coronary arterial blood flow and its cyclic variations as a function of time, has been designed and evaluated. The method combines densitometric analysis of spatial and temporal aspects concerning the contrast propagation through the arterial system from digital images, and is based on applying the concept of conservation of contrast material in successive images. It requires a standard arteriographic procedure. In simulations with both constant as well as pulsatile flow through a coronary arterial phantom, an excellent agreement with electromagnetic flow measurements was demonstrated (r = 0.993 and r = 0.982, respectively). Preliminary clinical results show, that the method yields reproducible assessment of coronary flow patterns after repeated injections in a patient. In a coronary artery bypass graft, coronary flow patterns in a baseline and a drug-induced hyperemic state were obtained. A consistent coronary flow reserve value was determined after repeated examinations. The method has been shown to be feasible in clinical applications, uncomplicated and fast, but requires further animal and clinical validation in order to determine the possible applications, limitations and accuracy.
Coronary Angiography↗
Quantitative studies on the nuclei of muscle of congenitally dystrophic mice.
Stereological analyses of the pattern of distribution of heterochromatin and euchromatin in nuclei of muscle fibres are reported. Patterns of distribution found in myonuclei from extensor digitorum longus muscle of C57BL/6Jdy2J/dy2J dystrophic mice were compared with those found in myonuclei from the same muscle of clinically unaffected littermates and of normal control mice. Using a well-known spatial pattern analysis technique, clear differences between these types of nuclei were found. Such differences are clearly of value in helping our understanding of the pathological processes occurring in dystrophic muscle, and may be relevant to future identification and diagnosis of abnormal muscle.
Animals↗
Spatial distribution of glutathione, glutathione-related and antioxidant enzymes in cultured mouse embryos.
The present study was undertaken to evaluate the detoxifying capacity of organogenesis-stage murine concepti cultured in vitro. Investigative attention was particularly focused on the embryonic tissue distribution of cytoprotective pathways. Glutathione (GSH) status, GSH-related and antioxidant enzymes were assayed in the embryo proper (EP), visceral yolk sac (VYS) and ectoplacental cone (EC) of 29.44 +/- 1.56 (mean +/- SD) somite pairs concepti. All the tissues displayed significant and comparable concentrations of GSH, further supporting this tripeptide as critical in protection against embryotoxicants. The totality of enzymatic activities was detectable in the selected embryonic compartments. In terms of spatial distribution analysis, maximal activities were found in EC (glutathione peroxidase, glutathione reductase, superoxide dismutase and glyoxalase I and II), and VYS (glutathione transferase and catalase). These results indicate: (1) the organogenesis-stage conceptus, in addition to significant amounts of GSH, expresses constitutive activities of GSH-related and antioxidant enzymes; (2) maximal activity levels are detectable in the embryonic sites which, at the developmental stage selected for assay, serve (VYS) or are evolving to serve (EC) embryo/maternal exchange, and thus represent the primary sites of interaction with foreign compounds.
Animals↗
Automatic motor cortex activation for natural as compared to awkward grips of a manipulable object.
It has been suggested that, relative to natural objects, man-made object representations in the brain are more specifically defined by functional properties that reflect how an object is used and/or what it is used for (Warrington and Shallice 1984). We recorded 123-channel event-related potentials (ERP) in healthy participants during a mental rotation task involving a manipulable (hammer) and a non-manipulable (church) object. Both stimuli had standard and mirror-image versions rotated in four different orientations, resulting for the manipulable object in some natural and some awkward grips. Using spatial cluster analysis, time periods were determined during which the ERP maps differed between stimulus conditions. Specific maps appeared for natural versus awkward grips with the manipulable object at a very early stage (60-116 ms) as well as during a later stage (180-280 ms). Source estimations derived from the topographic data indicated that during the second time window the left motor cortex was significantly activated in the case of natural grips. We argue that the motor programs that are semantically associated with the object are automatically activated when it is presented in graspable orientations.
Adult↗
Scalp distribution components of brain activity evoked by visual motion stimuli.
We analyzed the scalp distribution of electrical brain activity elicited by visual motion stimuli in 14 healthy adults. Stimuli were square-wave gratings of high or low contrast moving with a velocity of 4.9 deg/s on a computer monitor. Adaptation to motion was varied by changing the so-called duty cycle of stimulus presentation (i.e., the relation of motion to total presentation time) in order to enhance motion-related activity. Data obtained with motion stimuli were compared with checkerboard pattern reversal evoked activity. Spatial principal components analysis revealed four latent topographical components that accounted for 92.05% of the variance. Two components showed occipital extreme values surrounded by steep potential gradients while another two components displayed lateralized activity. Analysis of the contribution of these spatial components to the observed potential fields revealed significant differences between activity evoked by pattern reversal and that evoked by motion. The topographical patterns of cortical activation changed rapidly within 240 ms after motion onset. Our results confirm the sequential and parallel activation of different neuronal generators selectively sensitive to physical stimulus parameters of motion stimuli. The converging evidence of specialized quality-specific streams of sensory processing stemming from single-unit recordings in monkeys and imaging methods is supplemented by our electrophysiological results reflecting the activation of different brain areas.
Adaptation, Physiological↗
Quantification of Parkinson's disease-related network expression with ECD SPECT.
PURPOSE: Spatial covariance analysis has been used with FDG PET to identify a specific metabolic network associated with Parkinson's disease (PD). In the current study, we utilized a new, fully automated voxel-based method to quantify network expression in ECD SPECT images from patients with classical PD, patients with multiple system atrophy (MSA), and healthy control subjects. METHODS: We applied a previously validated voxel-based PD-related covariance pattern (PDRP) to quantify network expression in the ECD SPECT scans of 35 PD patients, 15 age- and disease severity-matched MSA patients, and 35 age-matched healthy control subjects. PDRP scores were compared across groups using analysis of variance. The sensitivity and specificity of the prospectively computed PDRP scores in the differential diagnosis of individual subjects were assessed by receiver operating characteristic (ROC) analysis. RESULTS: PDRP scores were significantly increased (p < 0.001) in the PD group relative to the MSA and control groups. ROC analysis indicated that the overall diagnostic accuracy of the PDRP measures was 0.91 (AUC). The optimal cutoff value was consistent with a sensitivity of 0.97 and a specificity of 0.80 and 0.71 for discriminating PD patients from MSA and normal controls, respectively. CONCLUSION: Our findings suggest that fully automated voxel-based network assessment techniques can be used to quantify network expression in the ECD SPECT scans of parkinsonian patients.
Algorithms↗
Privileged knowledge and social change: effects on different participants of using geographic information systems technology in natural resource management.
The use of geographic information systems (GIS) technology in natural resource management has expanded rapidly: It is the preferred tool of spatial data analysis addressing large landscapes and is typically the presentation medium for conveying landscape-scale scientific findings to all kinds of audiences. In a case study using the Coastal Landscape Analysis and Modeling Study in western Oregon, it was found that the use of GIS to analyze and display natural resource data in that project produced a variety of responses among different participants and participant groups. The findings offer insights into the workings of groups attempting public involvement in natural resource management.
Conservation of Natural Resources↗
Managing radioactively contaminated land: implications for habitat diversity.
Radioactive contamination of agricultural land may necessitate long-term changes in food production systems, through application of selected countermeasures, in order to reduce the accumulation of radionuclides in food. We quantified the impact of selected countermeasures on habitat diversity, using the hypothetical case of two agricultural areas in Finland. The management scenarios studied were conversions from grassland to cereal production and from grassland and crop production to afforestation. The two study sites differed with respect to present agricultural production: one being predominantly cereal production and seminatural grasslands, while the other was dominated by intensive grass and dairy production. Some of the management scenarios are expected to affect landscape structures and habitat diversity. These potential changes were assessed using a spatial pattern analysis program in connection with geographic information systems. The studied landscape changes resulted in a more monotonous landscape structure compared to the present management, by increasing the mean habitat patch size, reducing the total habitat edge length and reducing the overall habitat diversity calculated by the Shannon diversity index. The degree of change was dependent on the present agricultural management practice in the case study sites. Where dairy production was predominant, the landscape structure changes were mostly due to conversion of intensive pastures and grasslands to cereal production. In the area dominated by cereal production and seminatural grasslands, the greatest predicted impacts resulted from afforestation of meadows and pastures. The studied management changes are predicted to reduce biodiversity at the species level as well as diminishing species-rich habitats. This study has predicted prominent side effects in habitat diversity resulting from application of management scenarios. These potential long-term impacts should be considered by decision-makers when planning future strategies in the event of radionuclide deposition.
Agriculture↗
Expression of adhesion molecule T-cadherin is increased during neointima formation in experimental restenosis.
Phenotypic modulation, migration and proliferation of vascular smooth muscle cells (SMCs) are major events in restenosis after percutaneous transluminal angioplasty. Surface cell adhesion molecules, essential to morphogenesis and maintenance of adult tissue architecture, are likely to be involved, but little is known about cell adhesion molecules expressed on SMCs. T-cadherin is a glycosyl phosphatidylinositol-anchored member of the cadherin superfamily of adhesion molecules. Although highly expressed in vascular and cardiac tissues, its function in these tissues is unknown. We previously reported increased expression of T-cadherin in intimal SMCs in atherosclerotic lesions and proposed a role for T-cadherin in phenotype control. Here we performed immunohistochemical analysis of spatial and temporal changes in vascular T-cadherin expression following balloon catheterisation of the rat carotid artery. T-cadherin expression in SMCs markedly increases in the media early (1-4 days) after injury, and later (day 7-28) in forming neointima, especially in its preluminal area. Staining for monocyte/macrophage antigen ED-1, proliferating cell nuclear antigen and smooth muscle alpha-actin revealed that spatial and temporal changes in T-cadherin level coincided with the peak in cell migration and proliferation activity during neointima formation. In colchicine-treated cultures of rat aortic SMCs T-cadherin expression is increased in dividing M-phase cells but decreased in non-dividing cells. Together the data support an association between T-cadherin expression and SMC phenotype.
Angioplasty, Balloon↗
Subcellular localization, expression patterns, SNPs and association analyses of the porcine HUMMLC2B gene.
Myosin regulatory light chain (MLC) regulates myofilament activation via phosphorylation by Ca(2+) dependant myosin light chain kinase. In order to further understand the functions of the porcine fast myosin regulatory light chain gene (HUMMLC2B) in muscle, the subcellular localization, the temporal and spatial distributions of its gene product were analyzed, and the association between the presence of specific polymorphisms and commercial meat traits in pig was also examined. HUMMLC2B was demonstrated to localize both in the cytoplasm and the nucleus by confocal fluorescence microscopy. Real-time PCR further revealed HUMMLC2B expression variation in a waveform manner in the skeletal muscle of both Chinese Tongcheng and Western Landrace pig breeds at days 33, 65 and 90 post coitum (pc). After birth, the expression levels of HUMMLC2B were also found to decrease gradually with age. Our spatial expression analysis showed that HUMMLC2B was highly expressed in the semitendinosus, gastrocnemius, biceps femoris and longissimus dorsi muscles. In contrast, only low levels of expression of this gene were evident in fat, and no expression was detectable in brain, heart, kidney, lung, liver, lymph node, spleen, stomach, or in either large or small intestine. A total of 23 potential polymorphisms, comprising 3 exonic and 20 intronic, were detectable in the porcine HUMMLC2B gene and the G1094A, T1513C, G1876A and T2005G polymorphisms were further analyzed. The significant associations between the T1513C, G1876A and T2005G polymorphisms with marbling score, dressing percent and meat color, respectively, were identified (P < 0.05). Associations with the percentage of leaf fat could also be demonstrated by analysis of haplotypes harboring these three polymorphisms. Our current results thus shed further light on the roles and functions of the HUMMLC2B gene in muscle.
Animals↗
[Cleft lip and cleft palate birth rate in Bavaria before and after the Chernobyl nuclear power plant accident].
BACKGROUND: Cleft lip and palates (CLP) occur with a frequency of between 1 and 2 cases in 1000 live births and thus belong to the most frequent congenital anomalies. In the former German Democratic Republic (GDR), records covering 1967-1989 for CLP newborns show a 9.4% increase of the prevalence of CLP from 1987 to 1989, possibly due to Chernobyl. DATA AND STATISTICAL METHOD: In Bavaria, all congenital malformations in children's hospitals have been recorded from 1984 to 1991. Among these data, 1324 cases with CLP were found. A spatial-temporal analysis aimed at uncovering a possible association of the CLP occurrence with the Chernobyl fallout on a district level, as well as a synoptic analysis of the GDR and Bavarian data, were carried out. RESULTS: In Bavaria, from October 1986 to December 1990, the CLP frequency increased by 9.5% (p=0.10) relative to the trend as computed from the remaining years. The association of CLP rates with fallout on a district level is reflected by a significant relative risk (RR) per kBq/m(2) of RR=1.008 (p=0.03). A synoptic analysis of the Bavarian data and the GDR data restricted to the overlapping time window from 1984 to 1989 discloses a simultaneous significant jump of the CLP prevalence by 8.6% (p=0.02) after 1986. CONCLUSION: The presumption of a long-term increase of CLP after exposure to Chernobyl fallout is corroborated by the analysis of the Bavarian congenital malformation data.
Abnormalities, Radiation-Induced↗
Gene flow and spatio-temporal genetic variation among sympatric populations of Tetranychus kanzawai (Acari: Tetranychidae) occurring on different host plants, as estimated by microsatellite gene diversity.
We investigated spatio-temporal genetic variation in allele frequency and estimated gene flow among sympatric populations of Tetranychus kanzawai on different host plants by the use of microsatellite markers. In the analysis of spatial genetic variation, no isolation by distance was detected among the populations. Gene flow between populations on Hydrangea macrophylla and those on other host plants was relatively restricted, whereas the populations on Akebia quinata and Clerodendrum trichotomum were almost panmictic. Our study on temporal genetic variation showed (1) that population differentiation was slightly reduced during the period from April to May owing to frequent gene flow among populations; and (2) that population differentiation was greatly enhanced from May to October because of bottleneck effects. Genetic differentiation among T. kanzawai populations was caused by the effect of host plants rather than by the effect of geographic distance among populations, suggesting possibility of sympatric host race formation in this species.
Animals↗
Genetic evaluation of in situ conserved and reintroduced populations of wild rice (Oryza rufipogon: Poaceae) in China.
We evaluated the genetic consequences and efficiency of conservation practices in Oryza rufipogon using microsatellite DNA markers. Spatial autocorrelation analysis from 12 microsatellite loci revealed that microsatellite alleles were exclusively distributed in patches within the population, indicating that large populations were unlikely to be homogeneous. An in situ conserved stand of O. rufipogon, which has been protected by a concrete wall from a large population, captured only 67.9% of the total genetic variation of the previous large population. The concrete wall was built to protect the wild rice, but it acted more as a physical barrier to gene exchanges between the two sides. An assignment test revealed only 11.1% putative seed exchanges across the wall. A reintroduced population was found to be genetically very diverse. About 76.3% of the total genetic variation detected in other populations was captured in this reintroduced population, and 24.8% of the total genetic variation in this population was not found in other populations. These results display two important findings for conservation of O. rufipogon. First, conserving one part of a large population of O. rufipogon will not preserve an adequate sample of the genetic variability, since populations are not homogeneous, and genotype distribution varies among localities. Second, a reintroduced population is not genetically depauperate, but it is too early to assess its long-term survival.
China↗
Arsenic, cadmium, lead, and mercury in surface soils, Pueblo, Colorado: implications for population health risk.
Decades of intensive industrial and agricultural practices as well as rapid urbanization have left communities like Pueblo, Colorado facing potential health threats from pollution of its soils, air, water and food supply. To address such concerns about environmental contamination, we conducted an urban geochemical study of the city of Pueblo to offer insights into the potential chemical hazards in soil and inform priorities for future health studies and population interventions aimed at reducing exposures to inorganic substances. The current study characterizes the environmental landscape of Pueblo in terms of heavy metals, and relates this to population distributions. Soil was sampled within the city along transects and analyzed for arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb). We also profiled Pueblo's communities in terms of their socioeconomic status and demographics. ArcGIS 9.0 was used to perform exploratory spatial data analysis and generate community profiles and prediction maps. The topsoil in Pueblo contains more As, Cd, Hg and Pb than national soil averages, although average Hg content in Pueblo was within reported baseline ranges. The highest levels of As concentrations ranged between 56.6 and 66.5 ppm. Lead concentrations exceeded 300 ppm in several of Pueblo's residential communities. Elevated levels of lead are concentrated in low-income Hispanic and African-American communities. Areas of excessively high Cd concentration exist around Pueblo, including low income and minority communities, raising additional health and environmental justice concerns. Although the distribution patterns vary by element and may reflect both industrial and non-industrial sources, the study confirms that there is environmental contamination around Pueblo and underscores the need for a comprehensive public health approach to address environmental threats in urban communities.
Arsenic↗
Design of the blood group AB glycotope.
Although the nature of the blood groups A and B has been comprehensively studied for a long time, it is still unclear as to what exactly is the epitope that is recognized by antibodies having AB specificity, i.e. monoclonal and polyclonal antibodies which are capable of interacting equally well with the antigens GalNAcalpha 1-3(Fucalpha 1-2)Gal (A trisaccharide) and Galalpha 1-3(Fucalpha 1-2)Gal (B trisaccharide), but do not react with their common fragment Fucalpha 1-2Gal. We have supposed that besides Fucalpha 1-2Gal, A and B antigens have one more shared epitope. The trisaccharides A and B are practically identical from the conformational point of view, the only difference being situated at position 2 of Galalpha residue, i.e. trisaccharide A has a NHAc group, whereas trisaccharide B has a hydroxyl group (see formulas). We have hypothesized that the AB-epitope should be situated in the part of the molecule that is opposite to the NHAc group of GalNAc residue. In order to test this hypothesis we have synthesized a polymeric conjugate in such a way that de-N-acetylated A-trisaccharide is attached to a polymer via the nitrogen in position C-2 of the galactosamine residue. In this conjugate the supposed AB-epitope should be maximally accessible for antibodies from the solution, whereas the discrimination site of antigens A and B by the antibodies should be maximally hidden due to the close proximity of the polymer. Interaction with several anti-AB monoclonal antibodies revealed that a part of them really interacted with the synthetic AB-glycotope, thus confirming our hypothesis. Moreover, similar antibodies were revealed in the blood of healthy blood group 0 donors. Analysis of spatial models was performed in addition to identify the hydroxyl groups of Fuc, Galalpha, and Galbeta residues, which are particularly involved in the composition of the AB-glycotope.
ABO Blood-Group System↗
The axostat. IV. An analysis of the planar and spatial electrocardiographic indices of normal subjects as referred to an orthogonalized lead system.
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Electrocardiography↗