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PubMed1982

[Value of the space perception test for evaluation of the aptitude for precision work in geodesy].

The visual spatial localization ability of geodesy and cartography - employers and of the pupils trained for the mentioned profession has been examined. The examination has been based on work duration and the time of its performance. A correlation between the localization ability and the precision of the hand - movements required in everyday work has been proven. The better the movement precision, the more efficient the visual spatial localization. The length of work has not been significant. The test concerned appeared to be highly useful in geodesy for qualifying workers for the posts requiring good hands efficiency.

Adult↗
PubMed1995

On the functional organization in a biological structure: the example of enzyme organization.

In this paper, we have considered how the spatial localization of enzymatic reactions, ranging from the elementary type (one step) to that of a metabolic pathway in 2 different phases, may affect the stability of metabolite concentrations. The spatial localization of molecules in the reactions involves: (1) the confinement of some enzymes to cellular substructures (organelles, membranes, cytoskeleton, multienzyme complexes); (2) exchanges of metabolites between cellular substructures (local phase) and cytosol. This organization may be called as structural. Under these conditions, we have studied the dynamical behaviour of the metabolic pathway investigating the velocity of convergence towards the reference steady-state after perturbation of metabolite concentrations. This type of stability may be called as functional stability. We show that an increase in exchanges by diffusion of metabolites between the local phase and cytosol from one hand, or a decrease in the local phase volume on the other hand, result in an increase of the functional stability around the steady-state. This is verified for one step of the pathway as well as for the entire pathway or when the pathway is present in the local phase and in the cytosol.

Enzyme Stability↗
PubMed1993

Instantaneous VEP signal frequency analysis.

Various methods have been used in the analysis of visually evoked potential signals. Due to the high noise content of the ssVEP signal, the signal is usually filtered using averaging or an order statistic filter, and then analyzed for frequency content. A frequency analysis technique often employed is the short-time Fourier transform (STFT) which yields information about both the frequency content and the spatial localization simultaneously. In 1946, D. Gabor modified the STFT by using a Gaussian window instead of a Hanning, Hamming, etc. for optimal simultaneous location in time and frequency. The common problem with the windowed DFT/FFT is the ambiguity of the estimate of frequency at a point (frequency localization). This paper will introduce a frequency analysis technique utilizing the WMMR (weighted majority with minimum range) filter, which, while in the time domain, will determine the frequency and spatial properties of a ssVEP signal within one period. This technique has been shown to be robust to impulsive noise of up to 40% and also robust to independent and identically distributed (i.i.d.) noise and DC shifts, for frequency content and spatial localization analysis for sinusoidal signals. The WMMR technique will be compared to the Gabor STFT by application to steady state visual evoked potential data.

Animals↗
PubMed1982

Cortical noradrenaline depletion eliminates sparing of spatial learning after neonatal frontal cortex damage in the rat.

The possibility that cortical noradrenaline (NA) is necessary for the sparing of function that occurs after neonatal frontal cortex damage was examined. Spatial localization by rats with frontal cortex damage sustained neonatally was better than by rats with similar damage sustained as adults. The sparing was abolished in rats depleted of cortical noradrenaline by means of neonatal 6-hydroxydopamine (6-OHDA) administration. NA depletion alone did not affect spatial localization. These data are consistent with the notion that NA has some general function in maintaining some forms of plasticity in posterior cortex.

Animals↗
PubMed1993

Transmural saturation transfer analysis of the creatine kinase system in the mammalian heart.

31P NMR spatial localization and saturation transfer techniques were combined to enable the transmural measurement of the forward creatine kinase (CK) rate (ATP:creatine N-phosphotransferase, EC 2.7.3.2.) in the in vivo canine myocardium. Five epicardial towards endocardial regions of the left ventricle (LV) were simultaneously examined using spatially localized voxels. Although intraleft ventricular CP/ATP ratios were constant, the pseudo first order rate constant (k') and the forward creatine kinase rate (Rf) displayed a 61% variation across the LV wall. Because CK levels and calculated [ADP], [CP] and pH are transmurally invariant in the normal left ventricle, the observed changes in the Rf could not be explained by changes in the absolute levels of these substrates and of creatine kinase. In addition, because myocardial oxygen consumption rates are known to be higher in the endocardium, these results imply that forward creatine kinase rates are not directly related to oxidative phosphorylation rates.

Adenosine Diphosphate↗
PubMed1994

Spectroscopic imaging of circular voxels with a two-dimensional Fourier-series window technique.

Spatial localization with the spectroscopic imaging technique is normally implemented with the Fourier-transform approach, yielding rectangular voxels, with potentially significant cross-voxel contamination. Multidimensional Fourier-series window (FSW) is an alternate approach that generates single voxels of predetermined shape, with minimal out-of-voxel contamination. The spatial location of the voxel is shifted by means of postacquisition processing. A two-dimensional circular voxel is introduced, which for many in vivo applications is a good match of the region of interest. Phantom images illustrate the spatial distribution of signal intensity within the circular FSW voxels. Phantom spectroscopic studies show excellent spatial localization, with no detectable out-of-voxel contamination. The circular FSW voxel approach is implemented in human and animal model studies, demonstrating the technique's utility. This arbitrary shape approach can be extended to three dimensions, defining, for example, cylinders, spheres, or ellipsoids.

Adenosine Triphosphate↗
PubMed1995

Transmural distribution of 2-deoxyglucose uptake in normal and post-ischemic canine myocardium.

This investigation was performed to determine (i) whether 31P spatially localized 31P NMR spectroscopy could be utilized to determine the transmural distribution of 2-deoxyglucose (2DG) uptake in the in vivo canine heart and (ii) whether transmural 2DG uptake would be affected by a preceding ischemic insult. 2DG was infused and the accumulation of 2-deoxyglucose-6-phosphate (2DGP) was monitored (by means of spatially localized 31P NMR) in control hearts, in pharmacologically hyperperfused hearts, and in hearts subjected to four (5 min) occlusions of the left anterior descending coronary artery. Myocardial blood flow was measured with radioactive microspheres. In control hearts, subendocardial (ENDO) 2DGP contents were significantly higher than those in the subepicardium (EPI) being 3.8 +/- 0.3 and 2.2 +/- 0.2 mumol/g, respectively; the ENDO/EPI ratio of 2DGP was 1.70 +/- 0.21. During hyperperfusion blood flow increased approximately four-fold but 2DGP accumulation was not altered. ATP levels in post-ischemic myocardium were significantly decreased (ENDO more than EPI) and 2DGP accumulation in each layer was increased (p < 0.01 vs control); however, the ENDO/EPI ratio of 2DGP was not altered. 2DG infusion induced a marked elevation of blood insulin and norepinephrine levels. These data demonstrate that in the presence of high blood levels of 2DG and insulin: (i) 2DGP accumulation can be measured in the in vivo canine heart; (ii) in normal hearts 2DG uptake is more pronounced in the inner layers of the left ventricular wall (this transmural 2DG uptake gradient is not due to subendocardial hypoperfusion); and (iii) 2DG uptake is greater in the post-ischemic heart but the ENDO/EPI gradient of 2DG uptake is not altered indicating that the more severe ischemic insult in the subendocardium does not result in a disproportionate increase in 2DG uptake in that region of the myocardium. Although 2DG uptake patterns in this model most probably reflect those of glucose (at comparable glucose and insulin levels), quantitative extrapolations with regard to the rate of glucose uptake are not possible from the present data.

Animals↗
PubMed1988

Monitoring positional information during oogenesis in adult Drosophila.

About 184P[lac, ry+]A insertions (O'Kane & Gehring, 1987) have been incorporated into the genome via P element-mediated transformation. The temporal-spatial localization of beta-galactosidase, synthesized by these insertions during oogenesis, is described. 32% present control levels of endogenous beta-galactosidase expression and 68% show novel patterns. 13% of the insertions are germline-specific; 33%, follicle-cell-specific; 20% are expressed in both germ line and follicle cells; and 2%, specific to the germarium. Several lines exhibit strict temporal-spatial localizations of beta-galactosidase; notably those expressed in specific populations of follicle cells. The results are discussed with respect to some of the positional information encoded in the genome to which the insertions respond, the use of the insertions as markers for cell differentiation and the potential of the technique for isolating new genes involved in egg production.

Animals↗
PubMed1991

Dissociation of object and spatial visual processing pathways in human extrastriate cortex.

The existence and neuroanatomical locations of separate extrastriate visual pathways for object recognition and spatial localization were investigated in healthy young men. Regional cerebral blood flow was measured by positron emission tomography and bolus injections of H2(15)O, while subjects performed face matching, dot-location matching, or sensorimotor control tasks. Both visual matching tasks activated lateral occipital cortex. Face discrimination alone activated a region of occipitotemporal cortex that was anterior and inferior to the occipital area activated by both tasks. The spatial location task alone activated a region of lateral superior parietal cortex. Perisylvian and anterior temporal cortices were not activated by either task. These results demonstrate the existence of three functionally dissociable regions of human visual extrastriate cortex. The ventral and dorsal locations of the regions specialized for object recognition and spatial localization, respectively, suggest some homology between human and nonhuman primate extrastriate cortex, with displacement in human brain, possibly related to the evolution of phylogenetically newer cortical areas.

Adult↗
PubMed1987

Random noise selective excitation pulses.

Several methods for the spatial localization of NMR signals from well-defined regions of tissue within extended specimens have been proposed. Most of these techniques are prone to signal error which can arise from large volumes of sample that surround the region of interest. These errors can theoretically be reduced by several orders of magnitude by the application of a radiofrequency prepulse. The pulse acts to randomize the unwanted spin magnetization prior to the application of a spatial localization technique.

Magnetic Resonance Spectroscopy↗
PubMed2026

The chemical landscape of plant surface metabolites: Acylsugars as models of ecological function and structural diversity.

Plants produce a multifunctional assortment of specialized metabolites that play important roles in defense, environmental adaptation, and ecological interactions. Among these compounds, acylsugars, nonvolatile metabolites produced primarily in glandular trichomes of Solanaceae species, have emerged as informative model systems for understanding plant surface chemistry. Differences in acyl chain length, branching pattern, saturation, and attachment position generate extensive chemical diversity that influences herbivore deterrence, pathogen resistance, and the physicochemical properties of leaf surfaces. Recent advances in analytical chemistry, particularly liquid chromatography-ion mobility-tandem mass spectrometry (LC-IM-MS/MS), have greatly improved the ability to separate structurally related acylsugar isomers and characterize metabolite complexity at high resolution. When integrated with genomics, transcriptomics, and emerging spatial metabolomics approaches, these analytical tools provide new insights into acylsugar biosynthesis, pathway regulation, evolutionary diversification, and ecological function across plant species. This review positions acylsugars, particularly those of Solanum species, as model systems for understanding how structural diversity, spatial localization, and specialized metabolism shape ecological and physiological function at plant surfaces. We examine acylsugar structural diversity, biosynthetic pathways, ecological and physiological functions, and interactions with environmental and atmospheric processes. Major challenges, including extensive isomeric complexity, incomplete pathway characterization, and difficulties linking chemical structure to biological function, are discussed alongside emerging opportunities in integrative omics, crop improvement, sustainable pest management, and environmental monitoring. Overall, acylsugars provide a powerful model for linking molecular structure, spatial localization, and ecological function, offering broader insight into how specialized metabolism shapes plant adaptation, defense, and environmental interactions.

Acylsugars↗
PubMed1989

Age, exercise, and coding performance.

We investigated the effects of exercise on the coding performance of young and older subjects. Hypotheses were tested that exercise either facilitates spatial localization or reduces susceptibility to distraction in older subjects. In a balanced design, we administered Digit Symbol and Symbol Digit coding tasks to exercisers and nonexercisers at two age levels under conditions of low or high within-task interference. The findings showed higher performance by the exercisers than by the nonexercisers only at the older age level and only with the Symbol Digit task. These findings support the hypothesis that exercise compensates for a loss of spatial localization skills with age. We found no evidence that susceptibility to distraction either increased with age or was affected by chronic exercise.

Adult↗
PubMed1992

Noradrenaline depletion blocks behavioral sparing and alters cortical morphogenesis after neonatal frontal cortex damage in rats.

The possibility that cortical noradrenaline (NA) is necessary for sparing of function that occurs after neonatal frontal cortex damage was examined. Spatial localization by rats with frontal cortex damage on postnatal day 7 (P7) was better than that by rats with similar damage sustained as adults. The sparing was abolished in rats depleted of cortical NA by means of neonatal 6-hydroxydopamine (6HDA) administration. The blockade of sparing in the P7 frontal operates was associated with a smaller brain, thinner cortex, and reduced cortical dendritic branching relative to saline-treated P7 frontal operates. NA depletion alone in unoperated rats did not affect spatial learning but did reduce brain size and dendritic branching. Rats with frontal lesions on P4 did not show sparing of spatial localization, and 6HDA administration had no additional behavioral effect. Overall, these data are consistent with the notion that NA has some general function in maintaining some forms of plasticity in posterior cortex.

Animals↗
PubMed1986

Sodium-23 magnetic resonance imaging of the eye and lens.

In order to develop a better understanding of cataract and to evaluate the effectiveness of potential drugs, noninvasive techniques must be devised to detect early metabolic changes. As a prelude to these goals, sodium-23 imaging experiments operating at 29.8 MHz (2.7 teslas) were performed on the bovine eye and lens. A spatially localized transverse relaxation time (T2)-weighted spin-density map of the sodium-23 within the lens is presented, with a resolution better than 250 micron. Due to the presence of short-T2 (3 msec) components within the lens, only the use of the planar-integral projection reconstruction (PPR) imaging scheme allowed sufficiently short echo-times (1 msec) to permit sodium-23 signal detection. These noninvasive imaging results show differences in the apparent sodium concentration within the lens that are consistent with separate, invasive measurements of sodium concentration. Separate analysis (with no spatial localization) at 79.4 MHz (7.2 teslas), using a shift reagent (dysprosium) to distinguish extracellular from intracellular sodium, indicates that approximately 62% of the detected sodium-23 signal is intracellular. These results are consistent with observations based on invasive measurements and further support the existence of the pump-leak system and a sodium gradient within the lens.

Animals↗
PubMed1988

Integrated MR imaging and spectroscopy with chemical shift imaging of P-31 at 1.5 T: initial clinical experience.

A section-selective three-dimensional phosphorus-31 chemical shift imaging (CSI) experiment was evaluated as the spatial localization method for spectroscopy in an integrated clinical magnetic resonance (MR) imaging and spectroscopy examination. The results of a CSI experiment can be displayed as either spectra related to specific voxels or "metabolite maps," in which the relative concentration of a given metabolite is displayed as an overlay of the MR image. This method was applied to the study of a soft-tissue mass and to a meningioma. The total imaging time in each case was 17 minutes with a voxel size of 27 cm3 in the extremity and 64 cm3 in the brain. The total time to set up this part of the study was about 10 minutes. No additional shimming was necessary when the center of the field of view selected for the CSI experiment was located at or near isocenter. The promising results obtained with this approach make the CSI method an attractive choice of spatial localization method.

Adult↗
PubMed1987

Immunocytochemical localization and spatial relation to the adenohypophysis of a somatostatin-like and a corticotropin-releasing factor-like peptide in the brain of four amphibian species.

The distribution of somatostatin (SRIF) - and corticotropin-releasing factor (CRF)-like - immunoreactive material was studied in the brain of four amphibian species (Ambystoma mexicanum, Pleurodeles waltlii, Xenopus laevis, Rana ridibunda) by use of immunocytochemistry. A wide network of SRIF-immunoreactive fibers and numerous perikarya were observed in all amphibians examined, with a dense accumulation of nerve endings in the external layer of the median eminence (ELME). In the representatives of the four amphibian species the CRF-like system was more circumscribed. Immunoreactive perikarya were present in the preoptic area, mainly in a ventrobasal position, and in the interpeduncular nucleus. The tract running along the ventral part of the tuber cinereum ends in the ELME facing the rostroventral lobe of the pars distalis that contains corticotrophs. CRF fibers were scarce or absent in the neural lobe. In all species studied in the present work, CRF fibers end in the area of the ELME close to the pituitary lobe containing corticotrophs. This correlation is similar to that reported for the Japanese quail and several teleosts.

Ambystoma↗
PubMed1994

Localizing the spatial and temporal electromagnetic fields on the axis of a lossy cylinder.

Given a specified form, both in time and space, for the electromagnetic fields on the axis of a lossy cylinder, we determine, analytically, the required azimuthally symmetric source distribution on the surface of the cylinder that generates such internal fields. We then show that this source is equivalent to an array with finite number of cylindrical slots in a metal encasing that are impulsed by specified voltages at a finite sequence of discrete times. A confirming forward calculation exhibits excellent agreement between the specified field form and that generated by the array of cylindrical slots. Potential applications are to hyperthermic cancer therapy, bioelectromagnetics and nondestructive testing.

Electromagnetic Fields↗