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PubMed2004

Spatial accessibility of primary care: concepts, methods and challenges.

Primary care is recognized as the most important form of healthcare for maintaining population health because it is relatively inexpensive, can be more easily delivered than specialty and inpatient care, and if properly distributed it is most effective in preventing disease progression on a large scale. Recent advances in the field of health geography have greatly improved our understanding of the role played by geographic distribution of health services in population health maintenance. However, most of this knowledge has accrued for hospital and specialty services and services in rural areas. Much less is known about the effect of distance to and supply of primary care on primary care utilization, particularly in the U.S.For several reasons the shortage of information is particularly acute for urban areas, where the majority of people live. First, explicit definitions and conceptualizations of healthcare access have not been widely used to guide research. An additional barrier to progress has been an overwhelming concern about affordability of care, which has garnered the majority of attention and research resources. Also, the most popular measures of spatial accessibility to care - travel impedance to nearest provider and supply level within bordered areas - lose validity in congested urban areas. Better measures are needed. Fortunately, some advances are occurring on the methodological front. These can improve our knowledge of all types of healthcare geography in all settings, including primary care in urban areas.This paper explains basic concepts and measurements of access, provides some historical background, outlines the major questions concerning geographic accessibility of primary care, describes recent developments in GIS and spatial analysis, and presents examples of promising work.

Journal Article↗
PubMed2006

Evaluating Michigan's community hospital access: spatial methods for decision support.

BACKGROUND: Community hospital placement is dictated by a diverse set of geographical factors and historical contingency. In the summer of 2004, a multi-organizational committee headed by the State of Michigan's Department of Community Health approached the authors of this paper with questions about how spatial analyses might be employed to develop a revised community hospital approval procedure. Three objectives were set. First, the committee needed visualizations of both the spatial pattern of Michigan's population and its 139 community hospitals. Second, the committee required a clear, defensible assessment methodology to quantify access to existing hospitals statewide, taking into account factors such as distance to nearest hospital and road network density to estimate travel time. Third, the committee wanted to contrast the spatial distribution of existing community hospitals with a theoretical configuration that best met statewide demand. This paper presents our efforts to first describe the distribution of Michigan's current community hospital pattern and its people, and second, develop two models, access-based and demand-based, to identify areas with inadequate access to existing hospitals. RESULTS: Using the product from the access-based model and contiguity and population criteria, two areas were identified as being "under-served." The lower area, located north/northeast of Detroit, contained the greater total land area and population of the two areas. The upper area was centered north of Grand Rapids. A demand-based model was applied to evaluate the existing facility arrangement by allocating daily bed demand in each ZIP code to the closest facility. We found 1,887 beds per day were demanded by ZIP centroids more than 16.1 kilometers from the nearest existing hospital. This represented 12.7% of the average statewide daily bed demand. If a 32.3 kilometer radius was employed, unmet demand dropped to 160 beds per day (1.1%). CONCLUSION: Both modeling approaches enable policymakers to identify under-served areas. Ultimately this paper is concerned with the intersection of spatial analysis and policymaking. Using the best scientific practice to identify locations of under-served populations based on many factors provides policymakers with a powerful tool for making good decisions.

Cluster Analysis↗
PubMed2006

Gene expression in cortex and hippocampus during acute pneumococcal meningitis.

BACKGROUND: Pneumococcal meningitis is associated with high mortality (approximately 30%) and morbidity. Up to 50% of survivors are affected by neurological sequelae due to a wide spectrum of brain injury mainly affecting the cortex and hippocampus. Despite this significant disease burden, the genetic program that regulates the host response leading to brain damage as a consequence of bacterial meningitis is largely unknown. We used an infant rat model of pneumococcal meningitis to assess gene expression profiles in cortex and hippocampus at 22 and 44 hours after infection and in controls at 22 h after mock-infection with saline. To analyze the biological significance of the data generated by Affymetrix DNA microarrays, a bioinformatics pipeline was used combining (i) a literature-profiling algorithm to cluster genes based on the vocabulary of abstracts indexed in MEDLINE (NCBI) and (ii) the self-organizing map (SOM), a clustering technique based on covariance in gene expression kinetics. RESULTS: Among 598 genes differentially regulated (change factor > or = 1.5; p < or = 0.05), 77% were automatically assigned to one of 11 functional groups with 94% accuracy. SOM disclosed six patterns of expression kinetics. Genes associated with growth control/neuroplasticity, signal transduction, cell death/survival, cytoskeleton, and immunity were generally upregulated. In contrast, genes related to neurotransmission and lipid metabolism were transiently downregulated on the whole. The majority of the genes associated with ionic homeostasis, neurotransmission, signal transduction and lipid metabolism were differentially regulated specifically in the hippocampus. Of the cell death/survival genes found to be continuously upregulated only in hippocampus, the majority are pro-apoptotic, while those continuously upregulated only in cortex are anti-apoptotic. CONCLUSION: Temporal and spatial analysis of gene expression in experimental pneumococcal meningitis identified potential targets for therapy.

Acute Disease↗
PubMed2006

Origin and identity of adrenocortical tumors in inhibin knockout mice: implications for cellular plasticity in the adrenal cortex.

Inhibin knockout (Inha-/-) mice develop gonadal sex-cord tumors and--when gonadectomized--adrenocortical tumors. Previous reports demonstrated that adrenocortical tumors from Inha-/- mice produce estrogen and depend on gonadotropin signaling for initiation. Here we show that, in addition to producing estrogen, the adrenocortical tumors display a global change in cellular identity, composed of two unique cell types expressing differing arrays of genes normally restricted to theca and granulosa cells of the ovary. Many of these genes are also induced in wild-type adrenals after gonadectomy or upon chronic gonadotropin stimulation, suggesting that the adrenal cortex normally contains a population of pluripotent cells that can be driven toward an adrenal or gonadal identity given the appropriate pituitary stimuli. A central feature of this altered cellular identity is the switch from predominant expression of Gata6 (endogenous to the adrenal cortex) to Gata4, which defines cellular identity in the ovary. We show that stable transfection of Gata4 in cultured adrenocortical cells is sufficient to activate ovarian-specific genes of both theca and granulose lineages. Spatial analysis of Gata4 expression reveals a distinct pattern of localization to the supcapsular region of the adrenal, which contains undifferentiated progenitor cells that continuously populate the adrenocortical zones. Although both wild-type and Inha-/- mice display this pattern, only Inha-/- mice produce tumors composed of these Gata4-positive cells. These data suggest that Inha-/- adrenocortical tumors cells are derived from pluripotent adrenocortical progenitor cells that adopt a gonadal fate due to the convergent loss of inhibin and chronic exposure to elevated gonadotropins.

Adrenal Cortex↗
PubMedDate not supplied

Vegetation pattern and heavy metal accumulation at a mine tailing at Gyöngyösoroszi, hungary.

Vegetation at an abandoned heavy metal bearing mine tailing may have multifunctional roles such as modification of water balance, erosion control and landscape rehabilitation. Research on the vegetation of mine tailings can provide useful information on tolerance, accumulation and translocation properties of species potentially applicable at moderately contaminated sites. Analyses of the relationship between heavy metal content (Pb, Zn and Cu) and vegetation in a mine tailing were carried out. These analyses included: (1) spatial analysis of relationship among heavy metal distribution, pH and vegetation patterns, and (2) analysis of heavy metal accumulation and translocation in some plant species. Presence of vegetation was found to be significantly dependent on pH value, which confirms that phytotoxicity is a function of element concentration in solution, which is primarily controlled by pH value in mine tailings. Among the most abundant plant species, dewberry (Rubus caesius), vipersbugloss (Echium vulgare), scarlet pimpernel (Anagallis arvensis) and narrowleaf plantain (Plantago lanceolata) accumulate significant amounts of Pb, Cu and Zn, while in the case of annual bluegrass (Poa annua) only Pb can be measured in elevated contents. Considering the translocation features, scarlet pimpernel, narrowleaf plantain, and dewberry accumulate heavy metals primarily in their roots, while heavy metal concentration in vipersbugloss and annual bluegrass is higher in the shoots.

Copper↗
PubMed2001

The place behind the case: leptospirosis risks and associated environmental conditions in a flood-related outbreak in Rio de Janeiro.

The environmental context in which a leptospirosis outbreak took place during the summer of 1996 in the Rio de Janeiro Western Region was examined by using spatial analysis of leptospirosis cases merged with socio-demographic data using Geographic Information System (GIS). Risk areas were mapped based on flood and solid waste accumulation information for the region. Incidence rates were calculated for each area by the division of number of cases per total population in the specific areas. Higher rates were observed for census tracts inside the flood risk area and in the vicinities of waste accumulation sites. These findings are in agreement with the expected risk of leptospirosis, evidencing the role of environmental and collective factors in the determination of the disease.

Animals↗
PubMed2006

Spatiotemporal clustering and association of Ephestia kuehniella (Lepidoptera: Pyralidae) and two of its parasitoids in bulk-stored wheat.

To assess the spatiotemporal distribution of insects in a flat storage containing wheat (Triticumn spp.), probe traps were suspended in the wheat bulk and inspected for captured insects at 15-d intervals, from June 2001 to August 2002. The grain bulk was 1 m in height, and traps were placed at the upper and the lower 0.5 m of the bulk. During the entire trapping period, 17 insect taxa were recorded. The most abundant species were Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) and its larval parasitoids Harbobracon hebetor (Say) (Hymenoptera: Braconidae) and Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae). Most individuals were found in the upper bulk part. The highest E. kuehniella trap catches were found between August and November 2001 and during June and July 2002. Of the two parasitoids, H. hebetor was more abundant than V. canescens, with the exception of winter and early spring, when both species occurred at low numbers, especially H. hebetor. Spatial analysis by distance indices (SADIE) spatiotemporal analysis showed significant clustering of species, especially during summer and autumn. Early in the season and during spring 2002, at low host numbers, V. canescens occupied the locations where E. kuehniella mainly aggregated, but with the increase of E. kuehniella population, H. hebetor occupied these host groups and replaced V canescens. Although the two parasitoids competed for the same host species, both species coexisted in the storage facility during the entire trapping period.

Animals↗
PubMed2004

Satellite remote sensing for urban growth assessment in Shaoxing City, Zhejiang Province.

Urban growth represents specific response to economic, demographic and environmental conditions. Rapid urbanization and industrializations have resulted in sharp land cover changes. The present investigation was carried out from Shaoxing City to quantify satellite-derived estimates of urban growth using a three-epoch time series Landsat TM data for the years 1984, 1997 and ETM 2000. The methodology used was based on post classification comparison. The use of GIS allowed spatial analysis of the data derived from remotely sensed images. Results showed that the built-up area surrounding Shaoxing City has expanded at an annual average of 7 km2. Analysis of the classified map showed that the physical growth of urban area is upsetting the other land cover classes such as farming, water resources, etc. The study conclusion mainly emphasized the need for sustainable urban capacity.

Algorithms↗
PubMed2006

Genetic differentiation in eastern European and western Asian populations of the liver fluke, Fasciola hepatica, as revealed by mitochondrial nad1 and cox1 genes.

Partial sequences of mitochondrial genes nad1 (316 bp) and cox1 (429 bp) were analyzed to estimate the variability of the liver fluke samples collected in 20 localities in Russia, Belarus, Ukraine, Bulgaria, Armenia, Azerbaijan, Georgia, Turkey, Turkmenistan, and China. The sequences had 4.1% (nad1) and 2.3% (cox1) of variable sites, and 13 and 10 haplotypes were identified among nad1 and cox1 genes, respectively. Spatial analysis of genetic and nucleotide diversity indicated little or no structuring of genetic variation between hosts or regions. The analysis of distribution of both separate and combined (nad1 + cox1) haplotypes revealed the existence of 2 well-defined lineages with 2 main haplotypes and a number of shared divergent haplotypes. Our study showed that the first lineage included the main N1-C1 haplotype, which was found in Australia, China, Georgia, Turkey, Armenia, Azerbaijan, and in all European populations (from Russia, Belarus, Ukraine, Bulgaria). The second lineage was found in all European populations and in populations from Armenia and Azerbaijan. It was suggested that one of the lineages (I) has an Asian origin. The possible source of mtDNA variability and associations between lineage divergence of parasite and its definitive hosts (cattle and sheep) are discussed.

Analysis of Variance↗
PubMed2003

Identifying pollution hot spots from polychlorinated biphenyl residues in birds of prey.

Techniques for determining whether patterns of points are random, clustered, or dispersed are well established; however, when the magnitude of the attribute at each location is also important, the situation is more problematic. The concentration of polychlorinated biphenyls (PCBs) in the livers of Eurasian sparrowhawks Accipiter nisus and common kestrels Falco tinnunculus has been determined for birds from all over Great Britain for several decades and forms a unique database. When mapped, there appears to be clusters of high values in some parts of the country. If these clusters are truly significant, then they may indicate pollution hot spots and possibly help identify undocumented sources of contamination. What constitutes a cluster is open to debate. We know something about the foraging behavior of birds of prey, but we do not know how many pollution sources (hot spots) there are, how long they persist, or over what area they may disperse PCBs. We used a Monte Carlo simulation approach to determine whether the visually prominent clusters of high PCB residues were significant features or merely illusions. The five largest nonoverlapping clusters (defined in terms of the total PCB concentration) were identified at a range of spatial scales. In addition to the total concentration and the number of observations, the weighted centroid of the clusters and which individual birds were involved were also recorded. This enabled us to determine the scale over which the candidate hot spot was stable. Comparing the magnitude of the observed clusters with those from the trial simulations determined the probability of nonrandomness in the original data set (at each spatial scale). Results showed that some clusters do exist but, in the majority of cases, apparent clusters identified by eye could not be considered an actual aggregation of high concentrations following spatial analysis.

Animals↗
PubMed2005

Geographic variation in the prevalence of macular disease among elderly medicare beneficiaries in Kansas.

This study used Medicare Part B claims and enrollment data to estimate the prevalence of macular disease in Kansas at county and area levels. Spatial analysis by aggregated county clusters was assessed with standardized prevalence ratios and 95% confidence intervals, and a thematic map was produced to illustrate geographic distribution. A total of 17888 unduplicated claims were identified among 335132 beneficiaries older than age 64 years. Compared with the state prevalence of 5.34%, the central agricultural area showed a disproportionately high macular disease prevalence.

Aged↗
PubMedDate not supplied

Association of urban runoff with coastal water quality in Orange County, California.

The associations between storm events, urban runoff, and coastal water quality have not been well investigated. A temporal and spatial analysis of 2 years of data was conducted to determine associations between urban river discharge and indicator bacteria levels for Southern California beaches and evaluate the contribution of anomalous precipitation to the association. Data show beaches next to rivers had the highest bacterial levels in both wet and dry seasons. Bacterial levels rose substantially across all sites during wet months, and river discharge and bacterial levels were all highest during the winter with the most rainfall. Precipitation was significantly associated (Spearman rank bivariate correlation, P < 0.01) with water discharged from the rivers. River discharge was significantly associated with bacterial levels at 20 out of 22 beaches, with the strongest associations at sites next to rivers. The results indicate that urban river discharge is a primary source of Southern California's coastal water pollution and, as a result, swimming at beaches near rivers may pose a significant public health risk. The strong association found between precipitation and water pollution may be relevant to studies of potential health effects associated with climate change.

Bathing Beaches↗
PubMed2001

Spatial distribution of seropositivity to the causative agent of granulocytic ehrlichiosis in dogs in California.

OBJECTIVE: To assess spatial and temporal patterns of seroprevalence among dogs in California to the causative agent of granulocytic ehrlichiosis (GE). SAMPLE POPULATION: Sera of 1,082 clinically normal dogs from 54 of 59 counties in California in 1997 to 1998. PROCEDURES: Serum-specific IgG reactivity to Ehrlichia equi was assessed by use of an immunofluorescent antibody assay, using E. equi-infected horse neutrophils as substrate. Data were analyzed, using a geographic information system. Spatial analysis of seroprevalence included first order Bayesian analysis of seroprevalence and second order analysis of clustering by K-function and Cuzick-Edwards tests. Monthly seroprevalence among dogs was examined by use of regression on monthly densities of Ixodes pacificus adults and nymphs. RESULTS: Seroprevalence among dogs to E. equi was 8.68%. Data were seasonally bimodal with highest prevalence in winter (when adult ticks were abundant) and a secondary peak in late spring (corresponding to nymphal ticks). Humboldt County had the highest seroprevalence (47.3%), and other northern coast range counties had seroprevalence from 15 to 30%. CONCLUSIONS AND CLINICAL RELEVANCE: The patchy distribution of exposure to Ehrlichia organisms is a subset of the distribution of the tick vector. This may reflect enzootic cycles or climatic or historical factors that limited the range of the disease. Dogs, horses, and humans from north coast range counties in California are at increased risk of GE. These data provide a background for assessing risk of infection in horses and dogs, depending on geographic location. Dogs may be sentinels for assessing risk of GE in humans.

Animals↗
PubMed1977

Cognitive style of Eastern European Jewish males.

A distinctive cognitive style showing high verbal--low spatial analysis ability emerged on intelligence test performances of Jewish male subjects of Eastern European extraction. This style is somewhat different from that of the normative population. It is hypothesized that genetic factors making for differential development of the cerebral hemispheres in these subjects interact with subcultural emphasis on verbal skills to produce the evidenced differences.

Cognition↗
PubMed1981

Lateralization of functions in the animal brain.

The study was performed on mice, rats, and cats. The techniques used were those of conditional reflexes and evoked potentials. The results obtained give proof of the existence of hemisphere specialization of the brain in animals, and some of its properties are described. Motor control is shown to be mainly connected with the left hemisphere. Spatial analysis is mainly lateralized in the right hemisphere, and time analysis in the left one. It has been found that differentiation of absolute characteristics is mainly determined by the right hemisphere, and of relative ones by the left hemisphere. In males the brain has been shown to be more asymmetrical than in females. Proof is given of genetic determination of interhemispheric asymmetry magnitude. It is suggested that interhemispheric asymmetry arose not under the influence of speech and right-handedness but is determined by some more fundamental factors.

Animals↗
PubMed1988

Current source density estimation and interpolation based on the spherical harmonic Fourier expansion.

A method for the spatial analysis of EEG and EP data, based on the spherical harmonic Fourier expansion (SHE) of scalp potential measurements, is described. This model provides efficient and accurate formulas for: (1) the computation of the surface Laplacian and (2) the interpolation of electrical potentials, current source densities, test statistics and other derived variables. Physiologically based simulation experiments show that the SHE method gives better estimates of the surface Laplacian than the commonly used finite difference method. Cross-validation studies for the objective comparison of different interpolation methods demonstrate the superiority of the SHE over the commonly used methods based on the weighted (inverse distance) average of the nearest three and four neighbor values.

Brain↗
PubMed2004

Dead crow reports and location of human West Nile virus cases, Chicago, 2002.

During the summer and fall of 2002, an epidemic (223 cases) and epizootic of West Nile virus infections occurred in Chicago. Retrospective spatial analysis demonstrated that age-adjusted human case rates were three times higher inside geographic areas with high early-season crow deaths than outside these areas.

Adolescent↗
PubMed2000

[Localization of attention related cortical structures by evoked potentials].

Attention is an ambiguous concept, difficult to direct implementation in neurophysiological studies. The paper presents application of the Continuous Attention Test (CAT) items as stimuli in event related potential (ERP) studies on attention. Stimuli with high demand of attention result in enlarged N1 component in occipital derivations. Spatial analysis revealed increased positivity in frontal derivations. Three-dimensional image of cortical current density by means of Low Resolution Electromagnetic Tomography (LORETA) revealed sources of N1 component in occipital, parietal and postero-temporal derivations with the maximal current value at 17 Brodmann area. After target stimuli increase of current density in frontal derivations was observed, with the maximal value in the left 9 Brodmann area.

Attention↗