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PubMed2002

The density and spatial distribution of GABAergic neurons, labelled using calcium binding proteins, in the anterior cingulate cortex in major depressive disorder, bipolar disorder, and schizophrenia.

BACKGROUND: There is strong evidence for the presence of a deficit in cortical gamma aminobutyric acid (GABA) neurotransmission in schizophrenia. In this investigation we have used the calcium binding proteins (CBPs) parvalbumin (PV), calretinin (CR), and calbindin-D28K (CB) as markers of these neuronal populations, and have characterized their pattern and density in schizophrenia, bipolar disorder (BPD), and major depressive disorder (MDD). METHODS: We examined the anterior cingulate cortex (ACC) in four groups of 15 brains each from subjects with schizophrenia, MDD, and BPD, and from control subjects. Using immunocytochemistry to identify these distinct neuronal populations, we quantified their areal density and spatial pattern organization. RESULTS: There were reductions in the density of CB-labeled neurons in layer 2 in schizophrenia (34%; p =.04) and BPD (33%; p =.05) compared with control subjects; however, after correction for multiple comparisons these findings no longer attained formal statistical significance. We observed no differences in the density of the neuronal populations labeled by CR or PV in any layer of the cortex in any disorder compared with control subjects. There was increased clustering among PV-labeled neurons in BPD compared with control subjects but no significant differences in the spatial organization of the other neuronal subpopulations in any disorder. CONCLUSIONS: The study provides some support for the presence of a deficit in GABAergic neurons in schizophrenia and shows that these changes are not specific to schizophrenia. The findings indicate that there may be a pathophysiological condition, shared by subjects with schizophrenia and BPD, which operates to selectively reduce the number or protein expression of CB-immunoreactive neurons.

Adult↗
PubMed2003

Random spatial distribution of Schistosoma mansoni and hookworm infections among school children within a single village.

Schistosomes and soil-transmitted helminths currently infect a third of the world's human population. An important feature of these parasitic infections is their focal distribution, which has significant implications for control. Only a few studies have been carried out at the microepidemiological scale, comparing infection levels among individuals or households within a single village. In this study, data are presented from a cross-sectional survey, examining all children attending a primary school in rural Côte d'Ivoire over several consecutive days for Schistosoma mansoni, soil-transmitted helminths, and intestinal protozoa. All houses in the main village were mapped, and school children were linked to these households for small-area spatial analyses. Comparison between the 260 school children who live within the main village and the 89 children who reside in nearby settlements revealed significant differences in the overall prevalence and intensity of infections with S. mansoni and hookworm, confirming the focal nature of these 2 parasites. On the other hand, S. mansoni and hookworm infections exhibited random spatial patterns within the main village. The validity of these results is discussed in the context of this epidemiological setting, drawing attention to the issue of scale. Our findings have direct implications for intervention because they call for a uniform, community-wide approach to control schistosomiasis and soil-transmitted helminthiasis. Implementation can be relatively straightforward, and the proposed control approach might be cost-effective and prove sustainable.

Adolescent↗
PubMed2000

The spatial distribution of nonrewarding artificial flowers affects pollinator attraction.

Many species of orchids that do not offer food rewards to pollinators bloom in clusters, early in the season, and are polymorphic for corolla colour. Previous studies suggest that the foraging behaviour of insect pollinators may select for early blooming and colour polymorphism. I tested whether pollinator behaviour can also favour aggregated flowering in these species, in a two-stage laboratory experiment on naïve bumblebees, Bombus terrestris (L.). In the first stage, the bees were allowed to forage on three colours of artificial flowers that contained sucrose rewards. In the second stage, I added nonrewarding flowers of a fourth colour and recorded the bees' visits to them. The four types of artificial flowers were either arranged in spatially distinct clusters, or were randomly intermingled. I used two reward schedules for each spatial arrangement: constant refilling of reward-containing flowers and probabilistic refilling. Bees that foraged on clustered flowers flew more often to the nonrewarding patch, and made more visits to nonrewarding flowers, than bees that foraged on intermingled flowers. This tendency was obtained both in the constant reward and in the probabilistic reward schedules. The results support the hypothesis that pollinator attraction may select for clustered, synchronized blooming in flowers that do not contain nectar and pollen rewards. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1993

Positive and negative regulatory regions control the spatial distribution of polygalacturonase transcription in tomato fruit pericarp.

The tomato fruit consists of a thick, fleshy pericarp composed predominantly of highly vacuolated parenchymatous cells, which surrounds the seeds. During ripening, the activation of gene expression results in dramatic biochemical and physiological changes in the pericarp. The polygalacturonase (PG) gene, unlike many fruit ripening-induced genes, is not activated by the increase in ethylene hormone concentration associated with the onset of ripening. To investigate ethylene concentration-independent gene transcription in ripe tomato fruit, we analyzed the expression of chimeric PG promoter-beta-glucuronidase (GUS) reporter gene fusions in transgenic tomato plants. We determined that a 1.4-kb PG promoter directs ripening-regulated transcription in outer pericarp but not in inner pericarp cells, with a sharp boundary of PG promoter activity located midway through the pericarp. Promoter deletion analysis indicated that a minimum of three promoter regions influence the spatial regulation of PG transcription. A positive regulatory region from -231 to -134 promotes gene transcription in the outer pericarp of ripe fruit. A second positive regulatory region from -806 to -443 extends gene activity to the inner pericarp. However, a negative regulatory region from -1411 to -1150 inhibits gene transcription in the inner pericarp. DNase I footprint analysis showed that nuclear proteins in unripe and ripe fruit interact with DNA sequences within each of these three regulatory regions. Thus, temporal and spatial control of PG transcription is mediated by the interaction of negative and positive regulatory promoter elements, resulting in gene activity in the outer pericarp but not the inner pericarp of ripe tomato fruit. The expression pattern of PG suggests that, although they are morphologically similar, there is a fundamental difference between the parenchymatous cells within the inner and outer pericarp.

Base Sequence↗
PubMed1995

Non-uniform spatial distributions of both the magnitude and phase of AC electric fields determine dielectrophoretic forces.

It is well known that the conventional dielectrophoretic force acting on a polarised particle in a non-uniform AC electric field is proportional to the in-phase component of the induced dipole moment and the non-uniformity of the field strength. In contrast, the travelling-wave-dielectrophoretic force that acts on a particle subjected to a travelling electric field is proportional to the out-of-phase component of the induced dipole moment. We derive a theory that unifies the description and interpretation of conventional dielectrophoretic and travelling-wave-dielectrophoretic forces. We show that a particle in a non-uniform AC electric field experiences a dielectrophoretic force due to spatial non-uniformities of the magnitude and the phase of the field interacting, respectively, with the in-phase and out-of-phase components of the induced dipole moment. The theory is used to explain the translational effects observed for particles in the presence of standing, travelling and rotating fields in several experimental electrode configurations. The good agreement found between the experimental observations and the theoretical predictions validate the theory.

Cell Movement↗
PubMed2001

Trends and spatial distribution of oral cancer mortality in São Paulo, Brazil, 1980-1998.

We assessed oral cancer mortality data in São Paulo to study trends of the disease and its distribution by areas of the city. We standardized death rates by gender and age group, and also supplied complementary information regarding oral cancer incidence. Oral cancer mortality remained stationary at high levels during the study period. Site-specific death rates revealed high figures for two categories of site: tongue and unspecified parts of mouth. Gum cancer death rates--the most easily diagnosed site-specific oral cancer at a routine dental examination--fell sharply, possibly as a consequence of the recent expansion in community dental health services in the city. In spite of this observation, the increase of death rates related to unspecified parts of the mouth points to the deficiencies of health services in detecting most of oral cancer cases early. Spatial data analysis enabled indication of areas and socio-economic factors associated with poorer profile in oral cancer mortality, important information for the targeting of health resources directed to the screening, prevention and education in oral cancer.

Adult↗
PubMed1975

A method for measuring the spatial distribution of tissue oxygen removal rates.

Distributions of oxygen removal rates are measured over cut surfaces of samples of recently excised tissue. The samples are initially equilibrated with a gas of known oxygen tension and the surface is occluded by bringing it into contact with the end of a glass rod which has a number of polarographic electrodes embedded in it. The oxygen removal rate in mm Hg/sec is calculated from the rate of fall of surface oxygen tension. 91 electrodes are arranged in an array with 0.5 mm separation and each gives an estimate of the oxygen removal rate with a spatial resolution of a few hundred microns. An artificial medium of uniform and controllable respiration rate was used to test the system. Spatial variations in oxygen removal rate were demonstrated in some transplantable rodent tumours.

Animals↗
PubMed1990

Spatial distribution of the electric field induced in volume by round and figure '8' magnetic coils: relevance to activation of sensory nerve fibers.

The electric fields induced in finite homogeneous volume conductors by a round and a figure '8' magnetic coil (MC) were measured and related to MC stimulation of the median nerve. The volume conductors, filled with isotonic saline, consisted of a large rectangular trough ('unrestricted') and a smaller trough, whose dimensions approximated human forearm ('restricted'). Various MC orientations were applied to the volume conductor. Bipolar recordings were obtained with a coaxial electrode, which measured the voltage gradient between the exposed edge of the cable shield and the central wire at its tip, 1 cm distant (a linear probe). The probe was moved in 3 dimensions, allowing computer reconstruction of the electric field as a function of the 3 spatial axes. When the probe was parallel to the plane of the round MC and tangential to the direction of current in its windings, the induced electric field was maximal; it tended towards zero when the probe was over the center of the MC, or when the probe, remaining parallel to the plane of the MC, was radial (i.e., perpendicular) to the direction of the current in the windings. For a variety of MC orientations, the electric field was consistently increased when the probe was adjacent and parallel to the edge of the trough, indicating the important effect of boundaries. The electric field was greatly increased focally when the round MC was applied orthogonally to the volume conductor, or when the figure '8' MC was applied tangentially (i.e., flat) to the volume conductor. With the figure '8' MC, a sharp central peak parallel to the long axis was bounded on each side by smaller (less than half amplitude) peaks. The findings from physical modeling led to correct predictions as to the most effective orientations of round and figure '8' MCs for eliciting sensory nerve action potentials (SNAPs) from the median nerve.

Action Potentials↗
PubMed2004

Methane emissions from a constructed wetland treating wastewater--seasonal and spatial distribution and dependence on edaphic factors.

Constructed wetlands for wastewater treatment have many advantages. They can be used for several purposes, for example, to reduce levels of organic matter and nutrients, and to retain toxic metals. However, most wetlands are inherently net sources of gaseous compounds like methane and nitrous oxide, which are of environmental concern due to their rapid current accumulation in the atmosphere and their potent global warming capacity. In order to determine the flux of methane from a constructed wetland a study was conducted over two growth seasons on a pilot scale wetland constructed to reduce nutrient levels in secondary treated wastewater. The emissions for the spring to autumn period averaged 141 mg CH(4)m(-2)d(-1) (S.D.=187), ranging from consumption of 375 mg CH(4)m(-2)d(-1) to emissions of 1739 mg CH(4)m(-2)d(-1). The spatial and temporal variations were large, but could be accounted for by measured environmental factors. Among these factors, sediment and water temperatures were significant in all cases and independent of the scale of analysis (r(2) up to 0.88).

Ecosystem↗
PubMed2002

Spatial distribution of the macrozoobenthos in the Solís Grande Stream estuary (Canelones-Maldonado, Uruguay).

The analysis of 24 quantitative macrobenthic samples taken from the Solís Grande Stream estuary yielded 10 species from a total of 4,446 individuals. It was verified that both species richness and diversity was lower than those recorded in nearby regions with similar environmental conditions. In contrast with other studies, a marked dominance of any of the present species was not verified. All the species recorded correspond to typical estuarine organisms. Abundance data were analysed with multivariate techniques and the results showed a relationship with salinity, mean diameter and the percentage of fine sand. According to the cluster analysis and the canonical correspondence analysis (CCA) four groups of stations were defined. The partition out of total variation of the species data showed that the amount of variation explained by the space alone was low. Spatial patterns observed and their possible causes are analysed and discussed in relation to the natural factors that acts in this coastal ecosystem.

Animals↗
PubMed1989

Tubulin isotype usage in vivo: a unique spatial distribution of the minor neuronal-specific beta-tubulin isotype in pheochromocytoma cells.

The neuronal cells of vertebrates express two beta-tubulin isotypes, called Class II and Class III, that are neuronal specific. In order to determine the distribution of the minor Class III isotype, site-directed antibodies were raised to synthetic peptides representing the carboxyl terminal, isotype-defining domains of the tubulins. These antibodies were applied to PC12 cells at various stages of differentiation. The Class III isotype was found to be expressed in undifferentiated PC12 cells as well as in cells at every stage of differentiation. The concentration of the Class III isotype, relative to the total beta-tubulin complement, did not change significantly. Indirect double immunofluorescence microscopy demonstrated that the Class III isotype was found in the soma and the neurites of differentiated PC12 cells; this spatial pattern of Class III expression paralleled the total beta-tubulin pattern. Although the anti-Class III antiserum could stain in vitro assembled neuronal microtubules in a filamentous pattern, a close examination of the Class III staining pattern in flattened PC12 cells revealed that this isotype was not incorporated into the nonaxoplasmic array of microtubules. Rather, the Class III isotype was localized in a nonfilamentous, granular pattern that was not readily extracted with nonionic detergent. Cells treated with taxol and then flattened and stained showed that the Class III isotype could be induced to assemble into microtubule bundles by taxol. Thus, the minor neuronal beta-tubulin isotype appears to be spatially specialized in its pattern of expression.

Adrenal Gland Neoplasms↗
PubMed2002

The spatial distribution of selective attention assessed using the multifocal visual evoked potential.

To determine the manner in which attention is distributed among numerous locations in the visual space, we used a multifocal recording technique that allowed simultaneous recordings of evoked cortical activity from 12 visual field areas out to 23.6 degrees. We found that multifocal visual evoked potential (mfVEP) amplitude was larger when a region of visual space was attended than when it was not attended. The magnitude of this effect was inversely related to visual field eccentricity and there was no attention-related modulation of VEP amplitude for the most eccentric region. In addition, we found that mfVEP amplitudes in the regions contiguous to the attended region could also be larger, depending upon their spatial relationship to the attended region. Specifically, amplitudes in more central regions on the 'meridian of attention' were larger when the subject attended anywhere along that meridian.

Attention↗
PubMed2000

The spatial distribution of behavior under varying frequencies of temporally scheduled water delivery.

Two studies evaluated the effects of response-independent water deliveries on the location (on the floor of the experimental chamber) and position (height) of rats' behavior. In both experiments, fixed-time schedules delivered water in two dispensers that were located at opposite ends of the chamber. In Experiment 1, the two schedules provided complementary frequencies of water deliveries while the overall number of deliveries stayed constant. In Experiment 2, one of the schedules delivered water twice as frequently as the other; this proportion was kept constant while the overall density of water deliveries changed systematically. In both experiments, a single position (height) of behavior was dominant. Also, the percentage of time allocated to each dispenser was roughly proportional to the percentage of water deliveries associated with the dispensers. These data and additional considerations support the importance of examining the spatial properties and patterning of behavior.

Animals↗
PubMed2001

Spatial distribution of factors that determine sporogonic development of malaria parasites in mosquitoes.

Mosquitoes transmit malaria, but only a few species permit the complete development and transmission of the parasite. Also, only a fraction of the ingested parasites develop in the vector. The attrition occurs in different compartments during the parasite's complex developmental scheme in the insect. A number of factors, both physical and biochemical, that affect the development have been proposed or demonstrated. Each of these factors is located within a specific space in the insect. We have divided this space into six compartments, which are distinct in their biochemical and biophysical nature: Endoperitrophic space, Peritrophic matrix, Ectopretrophic space, Midgut epithelium, Haemocoel and Salivary gland. Because factors that influence a particular stage of parasite development share the same microenvironment within these compartments, they must be considered collectively to exploit them for designing effective transmission blocking strategies. In this article we discuss these factors according to their spatial location in the mosquito.

Animals↗
PubMed2000

Spatial distribution of in-patient service use of psychiatric patients: somatic departments versus psychiatric units.

BACKGROUND: It has long been recognized that a high proportion of psychiatric patients are admitted to emergency, medical and surgical wards. However, until now no assessment has been made of which urban general hospitals would be most appropriate for the establishment of specific psychiatric facilities. METHOD: Our study concerned Germany's second largest city, Hamburg (population 1.7 million), and involved an evaluation of psychiatric principal diagnoses in general and psychiatric hospitals. The research was based on data collected between 1988 and 1994 embracing approximately 77% of all psychiatric patients (n = 64,000) in 41 hospitals. The evaluation was carried out using the statistics programs SPSS and DismapWin. RESULTS: We established that the proportion of male patients discharged from somatic wards, mainly internal medicine, with alcohol and drug abuse as well as with neuroses and personality disorders or illegal drug abuse was surprisingly high (70%, 34% and 24% respectively). For female patients the figures were 67%, 40% and 35% respectively. A geographical analysis of spatial heterogeneity of hospitalization risks showed that general hospitals admit a disproportionately high number of patients from areas of lower social status - both male and female from the above-mentioned diagnostic categories. A rank correlation between the classification of areas based on the heterogeneity model and the social status of the areas supports this hypothesis, at least for males. CONCLUSION: Our findings lead us to the conclusion that the establishment of new psychiatric services should focus on internal wards in hospitals located in areas of low social status.

Adult↗
PubMed1994

Implications for bcd mRNA localization from spatial distribution of exu protein in Drosophila oogenesis.

Subcellular RNA localization in different cell types leads to asymmetric distribution of proteins in these cells. The localization of bicoid (bcd) messenger RNA to the anterior pole of the developing Drosophila oocyte gives rise in embryogenesis to a steep concentration gradient of the bcd protein, a transcription factor that activates expression of zygotic genes needed for anterior development. The exuperantia (exu) gene is necessary for this localization of bcd mRNA. Here we express a chimaeric gene encoding a fusion between the Acquorea victoria green fluorescent protein (GFP) and the exu protein (Exu) in female germ cells, and find that the fusion protein fluoresces strongly in both live and fixed cells during Drosophila oogenesis. The fusion protein rescues an exu null allele, restoring full fertility to females, and is expressed and localized in a temporal and spatial pattern similar to native Exu. The high sensitivity of the GFP tag provides important new details on the subcellular localization of Exu. The fusion protein is found in particles concentrated at ring canals, where transport occurs between nurse cells and the oocyte. Drugs such as colchicine and taxol that affect microtubule stability alter localization of the particles. We propose that the particles are ribonucleoprotein complexes or vesicles which transport bcd mRNA along microtubules and target it to the anterior oocyte cortex.

Animals↗
PubMed2004

Spatial distribution of heavy metals of agricultural soils in Dongguan, China.

Distribution and speciation of heavy metals of agricultural soils(85 surface soil samples and 4 soil profiles) in Dongguan were investigated, while total Cr, Cu, Ni, Pb, Zn(abbreviated as Cr, Cu, Ni, Pb, Zn) and available Cu, Zn(Av-Cu, Av-Zn) were analyzed by a flame absorption spectrophotometer(AAS), and total Cd(Cd) was analyzed using graphite furnace AAS. The content of Cd, Cu and Ni was partially much more than the second grade of GB15618-1995 even though the mean contents of all heavy metal were less than the threshold value of the second grade and only the mean content of Pb was more than the value of national background. Results of descriptive statistic showed that the mean content of heavy metals should depend on land utilization and spatial location at some extent. The heavy metal contents were higher in the Southwest and Northwest than in the Central. In addition, the mean contents of Zn and Pb in Dongguan paddy soils were significantly higher than those of Pearl River Delta(PRD) and Taihu Lake region(TLR). Correlation analyses indicated that there existed significant correlation between Cr and Ni in orchard soils, and among Zn, Cd and Cu, between Av-Cu and Cu, between Av-Zn and Cr, Ni, pH value in vegetable soils, and a weak relationship between Cd, Cu and Pb, between Av-Zn and Zn. Principal component analyses(PCA) showed that the order of importance should be Zn > Pb > Cr > Ni > Cu.

Agriculture↗
PubMed2000

Spatial distribution of blood flow in electrically stimulated human muscle: a positron emission tomography study.

Neuromuscular electrical stimulation (NMES) was studied with positron emission tomography (PET) and H(2)(15)O in the quadriceps muscle of 11 men. The subjects were submitted to simultaneous bilateral isometric contraction (5 s)-rest (5 s) cycles for 12 min, with a workload corresponding to 5% of quadriceps maximal isometric voluntary torque (QMIVT) for one thigh (5%T) and 10% of QMIVT for the other (10%T). Scans were centered at the electrodes and tissue blood flow (TBF) was evaluated in square regions of interest (ROIs) (3.5 cm(2)) in the transverse section (TS) of both thighs. The mean TBF reached 8.9 mL min(-1) 100 g(-1) in the TS of the 5%T and 11.5 mL min(-1) 100 g(-1) in the TS of the 10%T (P > 0.05). A negative linear relationship was found for both thighs between the ROI-electrode distance and the TBF (P </= 0.009). The mean percentage of activated ROIs (TBF > 5 mL min(-1) 100 g(-1)) was lower in the 5%T than in the 10%T (50.6% vs. 62.2%; P = 0.017). With NMES, the pattern of spatial recruitment appears linked to electrode proximity and is spatially extended. These results confirm the utility of combining NMES with voluntary exercise in the treatment of atrophied muscle.

Adult↗