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PubMed1996

Perception of visual motion with modulated velocity: effects of viewing distance and aperture size.

Subjects observed a random dot pattern that moved horizontally with modulated velocity within an invisible aperture. The velocity contrast, (V2-V1)/V1, was 2/3. Two different percepts occurred while observing this stimulus. At lower modulation frequencies, between 2 and 12 Hz, velocity changes were clearly seen; this percept is called "motion irregularity". At frequencies higher than 20 Hz velocity changes were no longer visible; the moving pattern appeared to be divided into stationary columns of different luminance. We call this percept "pattern irregularity". The critical frequency for detection of motion irregularity was independent of viewing distance; it was an inverted U-shaped function of the linear rather than the angular mean velocity of the pattern. At higher mean velocities the critical frequency increased with increasing aperture size; at lower mean velocities it was not affected by the size of the aperture. It is shown that detection performance is a function of the relative velocity of the pattern, i.e. of the ratio between the mean velocity in deg/sec and the aperture size in deg. Pattern irregularity could be detected at modulation frequencies even above 100 Hz. The critical frequency increased with increasing velocity and with decreasing viewing distance. It is suggested that detection of motion irregularity is determined by two distinct processes that are based on spatial analysis of motion at low relative velocities and temporal analysis at high relative velocities; both processes provide constancy of detection performance regardless of viewing distance. On the other hand, pattern irregularity seems to be detected on the basis of an analysis of the retinal luminance distribution at high modulation frequencies.

Adult↗

PubMed1995

Fingerprinting of DNA and RNA by arbitrarily primed polymerase chain reaction: applications in cancer research.

RNA fingerprinting by RAP-PCR is a powerful tool for the temporal and spatial analysis of differential gene expression. Many biological situations exist where differential gene expression results in distinguishable phenotypes, including, for example, tissue and cell types, responses to hormones, growth factors, stress, and the heterologous expression of certain genes. There are several methods for detecting differential gene expression and cloning differentially expressed genes that do not rely on a biological assay of phenotype. Most of these methods fall into two general categories: subtractive hybridization and differential screening. RAP-PCR offers numerous advantages over these methods, including its simplicity and its ability to compare the fluctuations in gene expression between multiple samples simultaneously using minute amounts of RNA. In addition, RAP-PCR can yield information on the overall patterns of gene expression between different cell types or between different physiological conditions of the same cell type. Comparison of the RAP-PCR fingerprints from these different experimental groups permits one to draw inferences regarding the overall cellular states of gene expression and the interrelation between gene transcripts belonging to the same or different regulatory pathways. Hypotheses regarding signal transduction pathways can be obtained using this information. RAP-PCR offers applications in cancer research in the detection of tumor-specific alterations in gene expression, providing a bountiful source of tumor markers. The pleiotropic impact of oncogene activation, tumor suppressor gene inactivation, and mutator mutations, in gene regulation, can be readily assessed by RAP-PCR in model systems both in vitro and in vivo.

Base Sequence↗

PubMed1992

Epidemiology of acute leukaemia in the Cape Province of South Africa.

Of 535 consecutive cases of acute leukaemia diagnosed in the Cape Province between 1978 and 1985, demographic data are incomplete in 75 black patients and they have had to be excluded from the spatial analysis. Of the remaining 460 cases, 223 (48.5%) occurred in white patients and 237 (51.5%) in those of mixed ancestry, classified as coloureds according to the Population Registration Act No. 30 of 1950. The average incidence was 2.12, 1.37 and 0.58/100,000 for whites, coloureds and blacks respectively. There was no temporal trend in the incidence of acute leukaemia between the three race groups. The median age for whites was 30 years and for the coloureds was 15 years, which is comparable to the 16 years for the black patients. The two-peak age distribution for leukaemia was seen in the white group, but was absent in the other two groups. This is accounted for by a different distribution in non-lymphoblastic as opposed to lymphoblastic subtypes. Furthermore, there was a disproportionately high frequency of acute progranulocytic leukaemia in the black patients, whereas the white and coloured groups were similar. There was a single, clearly defined macro-scale cluster restricted to white patients in Statistical Region 17 (SR-17). This exploratory study provides the first epidemiologic data for acute leukaemia in the Cape Province. It needs to be extended in order to verify these observations under more controlled circumstances and to seek evidence for some environmental factors that may account for the geographical cluster.

Acute Disease↗

PubMed1986

Topography of visual event-related potentials during geometric and phonetic discriminations.

Event-related potentials (ERPs) were obtained to letters during 3 tasks that involved a SIMPLE RESPONSE (SR) to each letter presentation, a FORM discrimination of the letters that formed a closed loop, and a RHYME discrimination of the letters that rhymed with the letter 'v'. The first task only required detection of the letters, the FORM task required a visual-spatial analysis, and the RHYME task, a grapheme-phoneme conversion of the letters followed by a determination of rhyming characteristics. The SR ERPs were morphologically different from the discriminative ERPs, notably by the absence of N2 and P3. The difference wave forms between the discrimination and SR conditions and between the targets and non-targets indicated differential topographies of components associated with the FORM and RHYME tasks in the 300 msec latency region. In both of these tasks, components exhibited distributions localized primarily in the occipital regions, whereas in the RHYME task they extended more anteriorly and encompassed temporo-parietal regions. Thus, although the stimulus presentation was visual, the requirement of a visual-auditory conversion in the RHYME task resulted in activity that was more proximal to auditory regions than when only a FORM analysis of the letters was required.

Adult↗

PubMed1993

Thiamine and folate treatment of chronic epileptic patients: a controlled study with the Wechsler IQ scale.

Seventy-two epileptic patients receiving phenytoin (PHT) alone or in combination with phenobarbital for more than 4 years were divided into four groups, the first taking two placebo tablets per day; the second folate (5 mg/day) and placebo; the third placebo and thiamine (50 mg/day); and the fourth both vitamins. The clinical trial lasted 6 months. At baseline assessment, 31% of the patients had subnormal blood thiamine levels and 30% had low folate. The vitamin deficiencies were independent phenomena. It was found that thiamine improved neuropsychological functions in both verbal and non-verbal IQ testing. In particular, higher scores were recorded on the block design, digit symbol, similarities and digit span subtests. Folate treatment was ineffective. These results indicate that, in epileptics chronically treated with PHT, thiamine improves neuropsychological functions, such as visuo-spatial analysis, visuo-motor speed and verbal abstracting ability.

Adult↗

PubMed2006

Reduction and redistribution of gap and adherens junction proteins after ischemia and reperfusion.

BACKGROUND: Previous studies have demonstrated that alterations in myocardial structure, consistent with tissue and sarcomere disruption as well as myofibril dissociation, occur after myocardial ischemia and reperfusion. In this study we determine the onset of these structural changes and their contribution to electrical conduction. METHODS: Langendorff perfused rabbit hearts (n = 47) were subjected to 0, 5, 10, 15, 20, 25, and 30 minutes global ischemia, followed by 120 minutes reperfusion. Hemodynamics were recorded and tissue samples were collected for histochemical and immunohistochemical studies. Orthogonal epicardial conduction velocities were measured, with temperature controlled, in a separate group of 10 hearts subjected to 0 or 30 minutes of global ischemia, followed by 120 minutes of reperfusion. RESULTS: Histochemical and quantitative light microscopy spatial analysis showed significantly increased longitudinal and transverse interfibrillar separation after 15 minutes or more of ischemia (p < 0.05 versus control). Confocal immunohistochemistry and Western blot analysis demonstrated significant reductions (p < .05 versus control) of the intercellular adherens junction protein, N-cadherin, and the active phosphorylated isoform of the principal gap junction protein, connexin 43 at more than 15 minutes of ischemia. Cellular redistribution of connexin 43 was also evidenced on immunohistochemistry. No change in integrin-beta1, an extracellular matrix attachment protein, or in epicardial conduction velocity anisotropy was observed. CONCLUSIONS: These data indicate that there are significant alterations in the structural integrity of the myocardium as well as gap and adherens junction protein expression with increasing global ischemia time. The changes occur coincident with previously observed significant decreases in postischemic functional recovery, but are not associated with altered expression of matrix binding proteins or electrical anisotropic conduction.

Adherens Junctions↗

PubMed2006

Neural networks of response shifting: influence of task speed and stimulus material.

Functional magnetic resonance imaging (fMRI) was used in 14 healthy subjects to measure brain activation, while response shifting was performed. In the activation phase, subjects were asked to shift their attention between two different types of visually presented stimuli. In the baseline phase, subjects were required to attend to one stimulus type only. Subjects responded by pressing a left or right key according to the side of presentation of the target stimuli. In a verbal task, subjects were required to switch between letters and numbers. In a figural task, subjects reacted to round and square shapes. Stimuli were presented for 750 or 1500 ms. Response shifting revealed significantly increased activation compared to non-switching in the bilateral superior parietal cortex, right occipital cortex, left inferior frontal cortex, left and right striatum, and bilateral dorsolateral prefrontal cortex (DLPFC). Superior parietal and occipital cortex activation may be due to spatial analysis during response shifting. Subvocal rehearsal of the task instructions may have led to activation in the left inferior frontal cortex. Activation in the striatum was related to prefrontal activation and may represent the association between basal ganglia and prefrontal activation during executive control. However, the most important brain region involved in the execution of response shifting was the bilateral DLPFC. Higher task speed increased executive top-down attentional control and, therefore, significantly increased activity in the bilateral DLPFC. Brain activation did not differ significantly between verbal and figural stimulus material. This result suggests that brain activation in the present study illustrates the brain regions involved in the basic cognitive mechanisms of response shifting.

Adult↗

PubMed2006

Removal of the ocular artifacts from EEG data using a cascaded spatio-temporal processing.

Eye movements and blinks may produce unusual voltage changes in human electroencephalogram (EEG). These effects may spread across scalp and mask brain signals. In this paper, a cascaded spatio-temporal processing procedure (CAST) is presented to remove artifact electrooculogram (EOG). Firstly a discrete equivalent distributed source on the cortical surface is reconstructed from the contaminated scalp recordings by a linear minimum norm estimation (i.e. a spatial analysis step). Then, the equivalent sources of EOG are identified by principal component analysis (PCA) of the equivalent distributed source time series (i.e. a temporal analysis step). Finally, the EOG-corrected scalp EEG is reconstructed from the equivalent distributed source where EOG components have been removed. The effectiveness of CAST is confirmed by the application to actual scalp data and a detailed comparative study.

Adult↗

PubMed2006

Neuropsychological functioning in opiate-dependent subjects receiving and following methadone maintenance treatment.

OBJECTIVE: An accumulating body of research suggests that former heroin abusers in methadone maintenance therapy (MMT) exhibit deficits in cognitive function. Whether these deficits are present in former methadone maintained patients following discontinuation of MMT is unknown. This study tests the hypothesis that former heroin users who have detoxified from methadone maintenance therapy and are drug-free have less pronounced cognitive impairment than patients continuing long-term MMT. METHOD: A series of neuropsychological tests were administered to three groups of subjects: 29 former heroin addicts receiving methadone maintenance treatment, 27 former heroin addicts withdrawn from all opiates, and 29 healthy controls without a history of drug dependence. Testing included Wechsler Adult Intelligence Scale-Revised Vocabulary Test, the Stroop Color-Word Test, the Controlled Oral Word Association Test, the Benton Visual Retention Test, and a Substance Use Inventory. FINDINGS: Both methadone-maintained and abstinent subject groups performed worse than controls on tasks that measured verbal function, visual-spatial analysis and memory, and resistance to distractibility. Abstinent subjects performed worse than their methadone maintained counterparts on tests measuring visual memory and construct formation. Cognitive impairment did not correlate with any index of drug use. CONCLUSIONS: We confirmed previous findings of neuropsychological impairment in long-term MMT recipients. Both patients receiving MMT and former heroin users in prolonged abstinence exhibited a similar degree of cognitive impairment. Cognitive dysfunction in patients receiving methadone maintenance may not resolve following methadone detoxification.

Adult↗

PubMed2005

Statewide mapping and assessment of vernal pools: a New Jersey case study.

In 2001, the New Jersey Department of Environmental Protection (NJDEP) adopted rules specifically protecting vernal pool habitat for the first time. Vernal pools are small isolated temporary bodies of water that provide critical breeding habitat for a number of amphibian species. To implement these rules and ultimately afford vernal pools protection, the NJDEP first needed to assemble a statewide database of vernal pool locations. In response, the Rutgers University Center for Remote Sensing and Spatial Analysis (CRSSA) was funded to develop a cost effective technique to map vernal pool locations statewide. The objective of CRSSA's mapping effort was to develop a complete potential vernal pool database to be able to identify individual isolated vernal pools as well as areas of high local density, or 'hotspots'. CRSSA used visual interpretation of leaf-off color infrared digital orthophotography in a computerized GIS environment to identify and map over 13,000 potential vernal pools. Using the 1m scale imagery, we determined the minimum detectable pool size to be on the order of 0.02 ha in size. Subsequent field checking has revealed a 12% error of commission that was due to our inclination towards erring on the side of inclusion in mapping many water features as potential vernal pools. For a vernal pool to receive regulated protection, it must be 'certified' that it serves as habitat for obligate or facultative vernal pool amphibian species. To aid in these efforts, CRSSA developed an interactive internet mapping site to assist NJDEP and its citizen volunteer corps in locating and navigating to their survey areas and to facilitate the on-line submittal of survey observations.

Amphibians↗

PubMed2006

Using expert judgments to understand spatial patterns of forest-based camping: a values-at-risk application.

Fire management agencies in Canada are mandated with protecting multiple forest values from wildfire. Deciding where to reduce fire hazard and how to allocate resources and fire suppression efforts requires an understanding of the values-at-risk from wildfire. The protection of recreation infrastructure is often assumed to provide adequate protection of recreation values. We use an expert judgment approach to provide a spatial distribution of recreation values-at-risk in the forested eastern slopes of the Rocky Mountain region of Alberta, Canada. Data were collected in 2004 from 11 land managers responsible for public lands management and wildfire prevention in the region. Expert assessments showed that recreation values were not confined to areas with publicly funded infrastructure. Exploratory spatial analysis of the ratings identified hotspots and cold spots of recreation activity. Maps resulting from these efforts will provide guidance to fire managers in the prioritization of fire management activities.

Alberta↗

PubMed2004

Functional MRI of visual-spatial processing in neurofibromatosis, type I.

Visual-spatial impairment and neuroanatomical abnormalities are considered hallmark features of neurofibromatosis, type I (NF-I). Numerous studies have demonstrated visual-spatial deficits in children with NF-I, but few relations between these deficits and neuroanatomical abnormalities have been identified. We compared the functional neuroanatomy of cerebral regions involved in the spatial transformation of alphanumeric stimuli in individuals with NF-I and healthy control participants using functional magnetic resonance imaging (fMRI). Given the prevalence of visual pathway abnormalities and visual-spatial deficits in NF-I, we hypothesized that less neuronal hemodynamic activity would be found in occipital and parietal cortices in this group compared with controls. However, NF-I participants relied to a greater degree than controls on posterior cortex (including occipital, parietal, and middle temporal cortices) relative to lateral and inferior frontal regions during visual-spatial analysis. This pattern was significantly related to their behavioral performance on the fMRI task, which in turn was also positively correlated with reading scores. These findings support evidence of frontal cortical anomalies in NF-I and may provide a pathophysiological basis for cognitive deficits in NF-I.

Adolescent↗

PubMed2026

Lactylation-related immune-metabolic dysregulation defines prognostic and therapeutic stratification in lung adenocarcinoma.

BACKGROUND: Lactylation links lactate metabolism with inflammatory signaling and immune regulation in tumors. However, its cellular distribution and translational value in lung adenocarcinoma (LUAD) remain unclear. METHODS: Single-cell RNA-sequencing datasets GSE189357 and GSE171145 were integrated to characterize lactylation-related activity, intercellular communication, and malignant epithelial cell states in LUAD. Single-cell-derived lactylation-related differentially expressed genes were mapped to TCGA-LUAD and multiple GEO cohorts. Univariate Cox regression and machine learning algorithms were used to construct a lactylation-related prognostic signature (LRPS). The associations of LRPS with prognosis, immunotherapy response, drug sensitivity, genomic alterations, immune infiltration, and inflammation- and metabolism-related pathways were evaluated. KRT7 was further validated using virtual knockout analysis, spatial transcriptomics, and in vitro and in vivo experiments. RESULTS: lactylation-related transcriptional activity showed heterogeneous distribution across LUAD cell populations and was associated with altered cell-cell communication. In malignant epithelial cells, LRTS-high and LRTS-low states exhibited distinct metabolic, inflammatory, and tumor-related pathway activities. LRPS showed stable prognostic performance in TCGA-LUAD and multiple GEO cohorts and remained an independent prognostic factor. Low LRPS was associated with greater potential benefit from immunotherapy, whereas different LRPS groups displayed distinct drug sensitivity, genomic alteration, and immune microenvironment patterns. KRT7 was highly expressed in LUAD and associated with poor prognosis. KRT7 knockdown suppressed LUAD cell proliferation, migration, invasion, colony formation, and tumor growth in vivo. CONCLUSIONS: This study identifies lactylation-related immune-metabolic dysregulation as a clinically relevant feature of LUAD and develops a single-cell-guided LRPS for prognosis and therapeutic stratification. KRT7 emerged as an LRPS-related functional candidate with experimentally supported roles in malignant LUAD phenotypes.

Immunotherapy↗

PubMed2006

Stable isotopes as one of nature's ecological recorders.

Analyses of the natural variation in stable isotopes of components of ecological systems have provided new insights into how these systems function across paleoecological to modern timescales and across a wide range of spatial scales. Isotope abundances of the molecules in biological materials and geochemical profiles are viewed as recorders that can be used to reconstruct ecological processes or to trace ecological activities. Here, we review key short-, medium- and long-term recording capacities of stable isotopes that are currently being applied to ecological questions. The melding of advances in genetics, biochemical profiling and spatial analysis with those in isotope analyses and modeling sophistication opens the door to an exciting future in ecological research.

Americas↗

PubMed2005

Distribution of human Oesophagostomum bifurcum, hookworm and Strongyloides stercoralis infections in northern Ghana.

A cross-sectional study was carried out in 216 randomly selected, representative rural villages in the northeastern part of Ghana from March 1995 to May 1998. Inhabitants of randomly selected households, stratified by age and gender, were included. The geographical position of villages was recorded with a global positioning system (GPS). The prevalence of Oesophagostomum, hookworm and Strongyloides stercoralis infections in a study population of 20250 people was determined by microscopic examination of larvae in stool cultures. The overall prevalence was 10.2, 50.6 and 11.6% for the three nematodes, respectively. Hookworm infections were seen in all but one (99.5%) and S. stercoralis in 88.4% of the 216 villages, while Oesophagostomum infections were found to be common in a limited area with prevalences varying from 0 to 75%. An association was found between Oesophagostomum and hookworm infection, both at the individual and at the village level. Spatial analysis of the prevalence data indicated that the endemic area is relatively clearly demarcated to the south of the study area.

Adolescent↗

PubMed2002

Molecular imaging of amyloid beta peptides in mouse brain sections using mass spectrometry.

A method is presented for direct spatial analysis of amyloid beta peptides in biological tissue sections. The technique takes advantage of the very high sensitivity of matrix-assisted laser desorption/ionization mass spectrometry and is implemented on a commercial instrument with modifications to only a few components and the software. With this setup, hundreds of molecular images can be generated simultaneously and within just a few minutes. The current features are an instrumental resolution of 50 microm and a sensitivity down to the attomol range. This new technology is applied to the study of amyloid beta peptide distribution in brain sections from mice, showing features reminiscent of Alzheimer's disease.

Alzheimer Disease↗

PubMed1999

Neglect without extinction.

A patient, AB, is reported who showed clear signs of neglect but no extinction (N+ E-). Several hypotheses proposed to account for this dissociation were put to the test. The postulated association between motor neglect and extinction did not hold good, nor did the possibility that the N+ E- dissociation may be traced back to the difference in test requirements and therefore observed only in patients with object-centred neglect. Likewise, manipulating the physical features of the stimuli (relative size, exposure time, presentation synchrony) did not elicit extinction. However, when the task demands were modified by asking the patient to perform a further spatial analysis of the stimuli, rather than simply detect them, extinction emerged. Since AB performed well on several neglect tasks requiring parallel processing, while failing all tasks calling for serial processing, the hypothesis is put forward that AB's N+ E- dissociation could be interpreted within the parallel/serial distinction framework.

Aged↗

PubMed1990

Double dissociation between temporal and spatial pattern processing in patients with frontal and parietal damage.

One hundred and twenty nine patients affected by a cerebral lesion confined to a single lobe, underwent a battery of tests including the "Temporal Rule Induction" (TRI) and the Raven's "Coloured Progressive Matrices" (CPM). Frontal patients scored lower than any other group on TRI and parietal patients on CPM. This contrasting pattern of performance provides strong empirical support to the hypothesis that the frontal lobe is specifically involved in tasks that require a control on temporally ordered information whereas the parietal lobe is concerned with cognitive activities that imply visuo-spatial analysis.

Adult↗