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PubMed2004

Spatial analysis reveals alterations of parvalbumin- and calbindin-positive local circuit neurons in the cerebral cortex of mutant mdx mice.

The aim of the present study was to investigate the spatial organization of selected populations of local circuit neurons in the cerebral cortex of the mutant mdx mouse, an acknowledged model of Duchenne Muscular Dystrophy. To this purpose, we quantified and compared the distribution of parvalbumin- and calbindin-positive neurons in the motor, somatosensory, visual, and anterior cingulate cortices of wild-type and mdx mice. The methodological approach was based on generation of two-dimensional Voronoi polygons from digital charts of the cell populations visualized immunohistochemically. Polygon areas were then analyzed and the derived coefficients of variation were statistically compared. Using this strategy, we were able to reveal, in mdx mice, changes involving both the above populations of interneurons. These changes were evident in the motor and anterior cingulate cortices but not in the somatosensory and visual cortices. In addition, the changes of coefficients of variation were area-specific in the cortex of mdx mice. The values increased in the motor cortex and decreased in the anterior cingulate cortex with respect to the corresponding values of wild-type animals. The present findings point out widespread alterations in the mdx cortex involving also areas not primarily related to sensorimotor integration. In addition, we demonstrate that cortical alterations of the local circuit machinery are characterized in mdx mice by individual regional differences.

Animals↗

PubMed2003

Spatial analysis of plant detritus processing in a Mediterranean river type: the case of the River Tirso Basin, Sardinia, Italy.

The river continuum concept represents the most general framework addressing the spatial variation of both structure and function in river ecosystems. In the Mediterranean ecoregion, summer drought events and dams constitute the main sources of local disturbance to the structure and functioning of river ecosystems occurring in the river basin. In this study, we analysed patterns of spatial variation of detritus processing in a 7th order river of the Mediterranean ecoregion (River Tirso, Sardinia-Italy) and in three 4th order sub-basins which were exposed to different summer drought pressures. The study was carried out on Phragmites australis and Alnus glutinosa leaf detritus at 31 field sites in seasonal field experiment. Detritus processing rates were higher for Alnus glutinosa than for Phragmites australis plant detritus. Processing rates of Alnus glutinosa leaves varied among seasons and study sites from 0.006 d(-1) to 0.189 d(-1) and those of Phragmites australis leaves ranged from 0.0008 d(-1) to 0.102 d(-1), with the lowest values occurring at sites exposed to summer drought. Seasons and sites accounted for a significant proportion of such variability. Alder detritus decay rates generally decreased with increasing stream order, while reed detritus decay rates generally increased on the same spatial gradient. Summer drought events affected these spatial patterns of variation by influencing significantly the decay rates of both plant detritus. The comparisons among and within sub-basins showed strong negative influence of summer drought on detritus processing rates. Similarly, in the entire River Tirso basin decay rates were always lower at disturbed than at undisturbed sites for each stream order; decay rates of reed detritus remained lower at those sites even after the end of the disturbance events, while alder decay rates recovered rapidly from the summer drought perturbations. The different recovery of the processing rates of the two leaves could also explain the different patterns of spatial variation observed between the two leaves.

Biodegradation, Environmental↗

PubMed2001

A spatial analysis of atmospheric ammonia and ammonium in the U.K.

As measures are implemented internationally to reduce SO2 and NOx emissions, attention is falling on the contribution of NH3 emissions to acidification, nitrogen eutrophication, and aerosol formation. In the U.K., a monitoring network has been established to measure the spatial distribution and long-term trends in atmospheric gaseous NH3 and aerosol NH4+. At the same time, an atmospheric chemistry and transport model, FRAME, has been developed with a focus on reduced nitrogen (NHx). The monitoring data are important to evaluate the model, while the model is essential for a more detailed spatial assessment. The national network is established with over 80 sampling locations. Measurements of NH3 and NH4+ (at up to 50 sites) have been made using a new low-cost denuder-filterpack system. Additionally, improved passive sampling methods for NH3 have been applied to explore local variability. The measurements confirm the high spatial variability of NH3 (annual means 0.06 to 11 microg NH3 m(-3)), consistent with its nature as a primary pollutant emitted from ground-level sources, while NH4+, being a slowly formed secondary product, shows much less spatial variability (0.14 to 2.4 mg NH4+ m(-3)). These features are reproduced in the FRAME model, which provides estimates at a 5-km level. Analysis of the underlying NH3 emission inventory shows that sheep emissions may have been underestimated and nonagricultural sources overestimated relative to emissions from cattle. The combination of model and measurements is applied to estimate spatial patterns of dry deposition to different vegetation types. The combined approach provides the basis to assess NHx responses across the U.K. to international emission controls.

Air Pollutants↗

PubMed2003

Spatial analysis of archaeal community structure in grassland soil.

The complex structure of soil and the heterogeneity of resources available to microorganisms have implications for sampling regimens when the structure and diversity of microbial communities are analyzed. To assess the heterogeneity in community structure, archaeal communities, which typically contain sequences belonging to the nonthermophilic Crenarchaeota, were examined at two contrasting spatial scales by using PCR-denaturing gradient gel electrophoresis (DGGE) analysis followed by unweighted pair group method with arithmetic mean analysis of 16S rRNA- and ribosomal DNA-derived profiles. A macroscale analysis was carried out with soil cores taken at 2-m intervals along triplicate 8-m transects from both managed (improved) and natural (unimproved) grassland rhizosphere soils. A microscale analysis was carried out with a single soil core by assessing the effects of both sample size (10, 1, and 0.1 g) and distance between samples. The much reduced complexity of archaeal profiles compared to the complexity typical of the bacterial community facilitated visual comparison of profiles based on band presence and revealed different levels of heterogeneity between sets of samples. At the macroscale level, heterogeneity over the transect could not be related to grassland type. Substantial heterogeneity was observed across both improved and unimproved transects, except for one improved transect that exhibited substantial homogeneity, so that profiles for a single core were largely representative of the entire transect. At the smaller scale, the heterogeneity of the archaeal community structure varied with sample size within a single 8- by 8-cm core. The archaeal DGGE profiles for replicate 10-g soil samples were similar, while those for 1-g samples and 0.1-g samples showed greater heterogeneity. In addition, there was no relationship between the archaeal profiles and the distance between 1- or 0.1-g samples, although relationships between community structure and distance of separation may occur at a smaller scale. Our findings demonstrate the care required when workers attempt to obtain a representative picture of microbial community structure in the soil environment.

Crenarchaeota↗

PubMed1999

Spatial analysis of the neuronal density of aminergic brainstem nuclei in primary neurodegenerative and vascular dementia: a comparative immunocytochemical and quantitative study using a graph method.

A graph method was employed to analyse spatial neuronal patterns of pontine nuclei with ascending aminergic projections to the forebrain (nucleus centralis superior (NCS), raphes dorsalis (NRD) and locus coeruleus (LC)), in Alzheimer disease (AD), Huntington disease (HD), and vascular (VD) as well as "mixed-type" (VA) dementia, compared with non-demented controls (CO) and a small sample of brains from schizophrenics ("dementia praecox" (DP)). The quantitative evaluations by the "minimal spanning tree (MST)" were complemented by rough neurofibrillary tangle (NFT) counts and by semiquantitative immunohistochemical assessment of amyloid deposition, neuritic plaque formation, and cellular gliosis. The AD cases showed a significant decline of neuronal density in all nuclei examined, as compared with controls and DP. Neuronal loss was not significant in VD, while the mixed cases with both vascular and Alzheimer-type pathology exhibited pronounced changes of neuronal density. Amyloid deposition occurred almost exclusively in AD and VA, as a rule, being of moderate degree, except for two presenile AD cases where it was marked. NFT were significantly increased in all nuclei in AD and in the VA cases, while they only occasionally appeared beyond age 55 in HD, DP and CO. The four HD cases showed in the NCS and NRD neuronal loss as severe as in AD. This neuronal loss implicates impairment of serotoninergic and noradrenergic neuromodulation as one basic mechanism promoting dementia in AD, VA and perhaps in HD.

Adult↗

PubMed1997

Social stress and trauma: synthesis and spatial analysis.

In the last decade violence has emerged as a public health issue, with concomitant interest in surveillance and prevention. This paper is an extension of earlier work seeking to expand the ecological analysis of violence across jurisdictional boundaries, sharpen the level of resolution of such analysis, and ultimately inform small area policy applications in terms of public health initiatives for violence reduction. The underlying model is drawn from stress theory and rests on a set of social indicators representing stress in the Baltimore area. In the earlier work, a set of 24 variables describing violence and socioeconomic conditions across some 1358 areas was factor analyzed and the resulting scores were mapped and interpreted. The present paper takes the analysis a step further in an attempt to identify groups of observations with common traits in order to assist public health professionals and other relevant decision-makers in the process of trauma surveillance, response, and prevention. Cluster analysis was used to combine most similar observations in terms of the three orthogonal factors, and the resulting cluster affiliations were mapped in geographic space. Although no spatial contiguity constraint was put on the clustering algorithm, many statistical clusters were also found to constitute geographic clusters. This implies that the process identified neighborhoods or parts of neighborhoods with shared traits in terms of the underlying set of stressors. Analysis of this type could be used by policy-makers to classify neighborhoods in terms of their needs for various services in addition to public health interventions, including policing, fire protection, building inspection, social work, and education.

Cluster Analysis↗

PubMed2005

Spatial analysis of lung, colorectal, and breast cancer on Cape Cod: an application of generalized additive models to case-control data.

BACKGROUND: The availability of geographic information from cancer and birth defect registries has increased public demands for investigation of perceived disease clusters. Many neighborhood-level cluster investigations are methodologically problematic, while maps made from registry data often ignore latency and many known risk factors. Population-based case-control and cohort studies provide a stronger foundation for spatial epidemiology because potential confounders and disease latency can be addressed. METHODS: We investigated the association between residence and colorectal, lung, and breast cancer on upper Cape Cod, Massachusetts (USA) using extensive data on covariates and residential history from two case-control studies for 1983-1993. We generated maps using generalized additive models, smoothing on longitude and latitude while adjusting for covariates. The resulting continuous surface estimates disease rates relative to the whole study area. We used permutation tests to examine the overall importance of location in the model and identify areas of increased and decreased risk. RESULTS: Maps of colorectal cancer were relatively flat. Assuming 15 years of latency, lung cancer was significantly elevated just northeast of the Massachusetts Military Reservation, although the result did not hold when we restricted to residences of longest duration. Earlier non-spatial epidemiology had found a weak association between lung cancer and proximity to gun and mortar positions on the reservation. Breast cancer hot spots tended to increase in magnitude as we increased latency and adjusted for covariates, indicating that confounders were partly hiding these areas. Significant breast cancer hot spots were located near known groundwater plumes and the Massachusetts Military Reservation. DISCUSSION: Spatial epidemiology of population-based case-control studies addresses many methodological criticisms of cluster studies and generates new exposure hypotheses. Our results provide evidence for spatial clustering of breast cancer on upper Cape Cod. The analysis suggests further investigation of the potential association between breast cancer and pollution plumes based on detailed exposure modeling.

Adult↗

PubMed2001

Spatial analysis of key signaling proteins by high-content solid-phase cytometry in Hep3B cells treated with an inhibitor of Cdc25 dual-specificity phosphatases.

Protein phosphorylation frequently results in the subcellular redistribution of key signaling molecules, and this spatial change is critical for their activity. Here we have probed the effects of a Cdc25 inhibitor, 2-(2-mercaptoethanol)-3-methyl-1,4-naphthoquinone, or Compound 5, on the spatial regulation and activation kinetics of tyrosine phosphorylation-dependent signaling events using two methods: (i) high-content, automated, fluorescence-based, solid-phase cytometry and (ii) a novel cellular assay for Cdc25A activity in intact cells. Immunofluorescence studies demonstrated that Compound 5 produced a concentration-dependent nuclear accumulation of phospho-Erk and phospho-p38, but not nuclear factor kappaB. Immunoblot analysis confirmed Erk phosphorylation and nuclear accumulation, and in vitro kinase assays showed that Compound 5-activated Erk was competent to phosphorylate its physiological substrate, the transcription factor Elk-1. Pretreatment of cells with the MEK inhibitor U-0126 prevented the induction by Compound 5 of phospho-Erk (but not phospho-p38) nuclear accumulation and protected cells from the antiproliferative effects of Compound 5. Overexpression of Cdc25A in whole cells caused dephosphorylation of Erk that was reversed by Compound 5. The data show that an inhibitor of Cdc25 increases Erk phosphorylation and nuclear accumulation and support the hypothesis that Cdc25A regulates Erk phosphorylation status.

3T3 Cells↗

PubMed1986

Immunization against whooping cough in Salford: a spatial analysis.

The decline in pertussis (whooping cough) immunization in the 1970s is related to public concern about the safety of the vaccine. The debates about its safety and effectiveness and the impact of vaccination on notifications are reviewed. A study is made of spatial variations in vaccine uptake within the metropolitan district of Salford, Greater Manchester, using data available at ward level. Salford as a whole has one of the lowest rates of uptake in the North Western Regional Authority, which itself has the lowest uptake in the country. Variations from ward to ward are noted and an attempt is made to account for these using Poisson regression. Both the number of children being immunized against pertussis and the number receiving diphtheria and tetanus vaccine (but foregoing the pertussis component) are used as dependent variables. Of the explanatory variables social class proves a useful predictor. However, the analysis is an ecological one and further work is called for at the scale of individual clinics in order to investigate health worker and parental attitudes and the accessibility constraints felt by those responsible for bringing children to clinics.

Child, Preschool↗

PubMed2003

Spatial analysis of cell death and Hsp70 induction in brain, thymus, and bone marrow of the hyperthermic rat.

Heat shock response and programmed cell death are cellular reactions to stressful stimuli. Previous studies have not correlated these responses in vivo at the spatial level in mammalian tissues. This study uses a dual procedure involving immunocytochemistry for Hsp70 localization and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end-labeling (TUNEL) assay for cell death to correlate the pattern of stress-inducible Hsp70 and cell death at the cellular level. After whole-body hyperthermia in the rat, an increase in Hsp70-positive cells and TUNEL-positive cells was noted in brain, thymus, and bone marrow. However, 2 populations of cells were apparent in the tissues examined, those inducing Hsp70 and those triggered into programmed cell death. Cells that were both Hsp70 positive and TUNEL positive were rarely detected. In tissues of the intact mammal, cells that induce Hsp70 after whole-body hyperthermia were not triggered into programmed cell death.

Animals↗

PubMed1985

Limitations of using medical records for the spatial analysis of health problems in Nigeria.

The objective of the paper is to examine the methods of keeping medical records in medical institutions in Nigeria and the limitations of present practices of record keeping to the study of various aspects of the spatial pattern of health problems in the country. There are suggestions of the type of additional information to be recorded about patients and methods of storage so that records at our health institutions can be more useful in understanding the health problems and needs of the country.

Delivery of Health Care↗

PubMed1997

New modeling methods: geographic information systems and spatial analysis.

Geographic factors, such as the location of alcohol outlets or of neighborhoods with different socioeconomic status within an area, can influence the patterns of alcohol use and alcohol-related problems in that area. Geographic information systems (GIS)--computer-based systems to capture, store, retrieve, analyze, and display spatial data--are increasingly used to investigate the effects of such geographic factors. GIS offer several key capabilities that facilitate alcohol-related geographic analyses, including geocoding (the linking of descriptive data, such as driving-while-intoxicated [DWI] events, to a location on a map), informative visual displays, and calculation of distance and adjacency. Using GIS-based data, researchers can perform complex spatial analyses of alcohol-related behaviors and problems, such as determining the correlation between DWI rates and geographic locations. These types of analyses may help investigators to understand environmental influences on alcohol-related problems and to plan and target appropriate prevention and intervention approaches.

Alcohol Drinking↗

PubMed2004

Spatial analysis for exclusive interactions between subgroups I and II of Cucumber mosaic virus in cowpea.

The dynamics of virus interference in Cucumber mosaic virus (CMV) infection in cowpea were investigated by tissue-blotting and in situ hybridization. Using co-inoculation assays, we discovered that spatial competition between CMV-LE (subgroup I) and CMV-m2 (subgroup II) occurred in the inoculated leaves. Interestingly, competitive interactions between the two viruses also could be observed in the non-inoculated upper leaf tissues of the plants. Furthermore, the pattern of exclusive distribution was observed between challenge and protecting viruses in the serially inoculated leaves. Taken together, it is suggested that the dynamics of competitive interactions between the two subgroups could be characterized by exclusive infection and multiplication of the individual viruses in cowpea plants.

Cucumovirus↗

PubMedDate not supplied

Exploratory spatial analysis of birth defect rates in an urban population.

Are birth defect rates unusually high in particular urban localities? The answer requires that the birth defect rate for which 'significance' is claimed be adjusted for the variable population sizes of each area for which the rate is computed and for the spatial dependence of rates based on shared observations between neighboring areas. By address-matching birth and birth defect records to a digital road map, we are able to compute local birth defect rates at regular grid locations by dividing the number of birth defects that occurred in the geographical vicinity of a grid location by the total number of births in the same vicinity. We test for significance, at regular spatial intervals, against the null hypothesis that the observed rate at any locality could reasonably have arisen by chance alone, given the underlying geographical variation in births. Significance is determined by using Monte Carlo simulations, where each birth location has an identical probability of being a defect. From 1000 simulations, a statistical distribution of the birth defect rate for each grid location is determined. The proportion of the simulated birth defect rates that are less than the observed rate at any grid location is the probability that the observed rate is significant. These probabilities, portrayed as isarithmic maps, show areas that have significantly high birth defect rates. Our results show birth defect rates for the period 1983 to 1990 in Des Moines, Iowa, U.S.A.

Cluster Analysis↗

PubMed2000

Pathology and compensation during visual signal processing in schizophrenia--spatial analysis of event-related potentials.

Correlations between measures of attention and topographical abnormalities of evoked cortical potentials elicited during the Continuous Attention Test (CAT) were assessed in 50 schizophrenic patients, compared to 50 healthy subjects. For each group and for each CAT condition evoked responses consisted of six successive epochs (segments) of stable spatially configured potentials. Quantitative descriptors of those configurations (Lehmann 1987) were referred to the CAT data. In patients: (1) segments III-V were delayed, (2) in the non-target condition, diminished global field power (GFP) emerged, coexisting either with lower amplitude of posterior potentials in segment I and II or with lower amplitude of a central positive potential in segment V, (3) an altered topographic pattern of responses to the target stimulus occurred. In healthy subjects detection of the target (as compared to the non-target condition) was associated with a shift of the location of the positive potential in segments IV and V from a central towards the prefrontal area. In patients, in segment V a similar shift reached frontal, but not prefrontal areas, and additionally, the central areas remained active. Delayed latency and low GFP in segment V in the non-target condition in patients correlated with poor CAT performance. A more posterior location of the positive centroid in segment V during detection of the target correlated with better CAT results, and the associated GFP increase with less prolonged reaction time. The data revealed a possible compensatory role of central and frontal areas in the face of weakened prefrontal functions in schizophrenia.

Adult↗

PubMed1980

A spatial analysis of the localization of cell division and cell death in relationship with the morphogenesis of the chick optic cup.

In an attempt to analyze the possible mechanisms underlying the morphogenesis of the optic cup and the optic fissure, two features of generally accepted morphogenetic importance, mitosis and cell death, were studied in their spatial distribution in the chick. The mitotic figures and necrotic remnants visible in serial sections as stained with Feulgen/naphthol yellow-S, were marked on photomicrographs and traced on glass-plates. By piling up the plates, glass reconstructions of five successive developmental phases in the course of the third day of incubation were obtained. Mitotic figures in the walls of the optic vesicle and cup appeared to be distributed at random in all phases. Four areas of cell death, in the lateral wall of the optic vesicle, in the ventral part of the proximal optic stalk, in the uppermost part of the optic cup rim and in the outer layer of the optic cup, were found lying in a frontal plane somewhat rostral from the center of invagination. Evidence for the role of local differences in cell division and localized cell death during the morphogenesis of the optic cup, was not found. Current theories in literature and our observations were discussed. We concluded that for the present, current or conceivable theories can only be teleological explanations of circumstantial evidence. A topographical relationship between cell death and the outgrowth of the optic nerve fibers probably does exist, however. This relationship is born out by studies of congenital anomalies. Possible avenues for further investigation are suggested.

Animals↗

PubMed2006

Surveillance of the colorectal cancer disparities among demographic subgroups: a spatial analysis.

OBJECTIVE: The literature suggests that colorectal cancer mortality in Texas is distributed inhomogeneously among specific demographic subgroups and in certain geographic regions over an extended period. To understand the extent of the demographic and geographic disparities, the present study examined colorectal cancer mortality in 15 demographic groups in Texas counties between 1990 and 2001. METHODS: The Spatial Scan Statistic was used to assess the standardized mortality ratio, duration and age-adjusted rates of excess mortality, and their respective p-values for testing the null hypothesis of homogeneity of geographic and temporal distribution. RESULTS: The study confirmed the excess mortality in some Texas counties found in the literature, identified 13 additional excess mortality regions, and found 4 health regions with persistent excess mortality involving several population subgroups. CONCLUSION: Health disparities of colorectal cancer mortality continue to exist in Texas demographic subpopulations. Health education and intervention programs should be directed to the at-risk subpopulations in the identified regions.

Black People↗

PubMed2006

Epidemiology and spatial analysis of malaria in the Northern Peruvian Amazon.

A retrospective surveillance study was conducted to examine the micro-geographic variation of malaria incidence in three malaria-endemic communities in the Northern Peruvian Amazon. The annual malaria risk rate (per 100) ranged from 38% to 47% for Plasmodium vivax and from 15% to 18% for P. falciparum. Spatial clusters were found for P. vivax in Padre Cocha, Manacamiri, and Zungaro Cocha, and for P. falciparum only in Padre Cocha. Spatial-temporal clusters showed that the highest monthly number of P. vivax cases varied every year from December to March in 1996-1997 and from February to June in 1998-1999, and for P. falciparum from November to April in 1996-1997 and from January to April in 1998-1999. Our results suggest a constant presence of high-risk areas (hot spots) for malaria infection in periods with high or low malaria incidence. Modest targeted control efforts directed at identified high-risk areas may have significant impact on malaria transmission in this region.

Cluster Analysis↗