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Results for “spatial sequencing”

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PubMedDate not supplied

[The neurocognitive profile of non-verbal learning disorder].

INTRODUCTION: Non-verbal learning disorder is a specific type of learning disorder that is characterised by difficulties in social skills, in visuospatial and visual-constructional capabilities, and in motor skills. AIM: To observe the cognitive profile characterising these children. PATIENTS AND METHODS: We evaluated the intelligence, memory, visuospatial functions, instrumental and executive functions of 13 children between 8 and 14 years of age diagnosed with non-verbal learning disorder. RESULTS: All the children displayed an overall intelligence quotient within a range considered to be normal, with a marked difference between the verbal and manipulative intelligence quotients. They all had a good verbal memory. In contrast, they had difficulties in any tasks requiring spatial organisation and sequencing. Spontaneous language was fluent and aprosodic, with poor non-verbal communication. CONCLUSIONS: Good verbal skills and marked deficits in visuospatial skills are the characteristic pattern that has been described in the literature and this coincides with the observations made in the 13 children under study.

Adolescent↗

PubMed1986

[Antroduodenal coordination].

The function of the antro-duodenal segment depends on the spatial and temporal sequence of contractions. This process can be defined as antroduodenal coordination. There is no constantly increased pressure in the antro-duodenal transition zone. During the interdigestive phase a coordination of gastral and duodenal motility, gastric acid secretion and bile-flow into the duodenum can be demonstrated. During phase II of the interdigestive phase a pressure gradient, proximal and distal, is observed in the gastroduodenal transition zone with peak values in the pyloric and duodenal bulb area. Cisapride and metoclopramide stimulate antral and duodenal motility, cisapride causes a significant increase in gastroduodenal coordination.

Animals↗

PubMed1978

Postembryonic development of the visual system of the locust, Schistocerca gregaria. I. Patterns of growth and developmental interactions in the retina and optic lobe.

The visual system of the locust, Schistocerca gregaria, has a highly ordered and predictable arrangement of neurons. The retina and the outermost layer, or lamina, of the optic lobe are each composed of repeating units, ommatidia and cartridges respectively. Each ommatidium has eight photoreceptor cells, which send axons directly to a group of five neurons in the lamina to form the cartridge. The importance, for the development of this precise pattern, of the mode of growth of the two arrays and of interactions between them was investigated. The spatial and temporal sequences of cell proliferation, differentiation and death in the developing retina and optic lobe were examined quantitatively under normal and experimental conditions. The retina grows from its anterior margin by addition of new ommatidia formed from recruited epidermal cells. The lamina also grows by addition of new neurons to its anterior margin, but these neurons are derived from a stem cell population. The parallel pattern of growth of the retina and lamina may be important for the formation of neuronal connexions between them. The retina grows and differentiates even when deprived of the underlying lamina. In laminae deprived of the ingrowth of new axons from the retina, the production of new neurons is also autonomous, but these neurons do not differentiate, but degenerate. A limited amount of cell death occurs in the laminae of control insects. These two observations suggest that a plausible mechanism for coordinating the sizes of the two arrays during normal development might be production of lamina neurons in excess of requirements and death of those remaining non-innervated.

Animals↗

PubMed1995

Essential hypertension and neurovascular compression at the ventrolateral medulla oblongata: MR evaluation.

PURPOSE: To investigate, using MR imaging, neurovascular compression at the ventrolateral medulla oblongata in patients with essential hypertension. METHODS: Thirty-two patients with essential hypertension (57.6 +/- 7 years of age), 6 patients with secondary hypertension (56.7 +/- 10.3 years of age), and 18 control subjects (50.5 +/- 11 years of age) were evaluated. Transaxial three-dimensional fast low angle shot images were obtained (38/6/1 [repetition time/echo time/excitations]). The center of a 40-mm-thick slab (16 partitions) was placed at the pontomedullary junction. We evaluated the relationships between the upper ventrolateral medulla and the vertebral arteries and branches identified by their flow-related hyperintensities in each group. RESULTS: In the essential hypertension group, 29 (90.6%) of 32 cases showed neurovascular compression. Of those, 22 demonstrated neurovascular compression on the left side, 3 on both sides, and 4 on the right side. In the control group, 4 cases of 18 showed neurovascular compression. In the secondary hypertension group, 1 of 6 cases showed neurovascular compression. The rates of observed neurovascular compression between controls and essential hypertension group were statistically significant. CONCLUSION: We found a close correlation between essential hypertension and neurovascular compression at the ventrolateral medulla oblongata on the left side. MR with a 3-D fast low-angle shot sequence has acceptable spatial resolution and depicts blood vessels simultaneously by flow-related phenomena.

Adult↗

PubMed1994

Interventional use of magnetic resonance imaging.

Among the currently available imaging techniques, magnetic resonance imaging (MRI) offers particular advantages for guiding, monitoring, and controlling diagnostic and therapeutic interventions, with particular appeal for most of the minimally invasive, minimal access approaches. The most obvious role of MRI is in monitoring and controlling a variety of interstitial ablative procedures, utilizing methods including thermal therapy (interstitial laser therapy, cryosurgery, focused ultrasound surgery). A fundamental requirement of MR monitoring is the implementation of pulse sequences with appropriate spatial and temporal resolution as well as overall image quality suitable for the dynamic imaging task. In addition, there is a need for a more accessible magnet configuration to enable execution of various interventional procedures. MR compatibility of instruments and devices, therefore, needs to be addressed, as must the integration of therapy delivery modalities with the MR system.

Humans↗

PubMed1994

Assessment of MR image deformation for stereotactic neurosurgery using a tagging sequence.

A tagging sequence is used to assess MR image deformations before a stereotactic neurosurgical procedure, in a test model and in two patients. This pulse sequence super-imposes narrow parallel orthogonal tag lines on an image, which can be used as an internal reference frame. Image deformation is directly related to surface area variations in the squares produced by the tagging-sequence pulses. Small spatial deformations of the tags can be detected on the images used for measuring stereotactic-target spatial coordinates. A threshold of 2 SD guarantees that the distortion is smaller than one pixel.

Biopsy↗

PubMed1996

Activity-independent segregation of excitatory and inhibitory synaptic terminals in cultured hippocampal neurons.

Cultured hippocampal neurons were used as a model system to address experimentally the spatial and temporal sequence leading to the appropriate sorting of excitatory and inhibitory synaptic terminals to different cellular target domains and the role of neural activity in this process. By using antibodies against glutamic acid decarboxylase 65 (GAD65) and synaptophysin, we examined the development and segregation of GABAergic and non-GABAergic synaptic terminals on single neurons. Electron microscopy confirmed that GAD65-labeled swellings observed using light microscopy corresponded to synaptic boutons. From the time at which GABAergic terminals first appeared, they developed at a more rapid rate on neuronal somata than non-GABAergic terminals did, such that by 18 d in culture, 60% of the total boutons on somata were GABAergic. By contrast, the majority (70%) of boutons on dendrites were non-GABAergic. These data suggest that inhibitory synaptic terminals are targeted preferentially to or maintained on cell somata at the expense of excitatory terminals. Interestingly, non-GABAergic terminals were not inhibited from forming synapses on cell somata, because in the absence of GABAergic terminals they attained the same total somatic terminal density seen in the presence of GABAergic terminals. Chronic blockade of neuronal activity did not affect the differential targeting of GABAergic and non-GABAergic axons; however, it did reduce the extent of dendritic arborization. Our findings support a two-step model for synaptic segregation whereby the majority of terminals is initially targeted in an activity-independent manner to the appropriate cellular domains, but an additional developmental mechanism serves to further restrict and refine the original synaptic distribution.

Animals↗

PubMed1997

Early malnutrition and child neurobehavioral development: insights from the study of children of diabetic mothers.

In this study we sought to discern whether disturbances in mothers' metabolism during pregnancy may exert long-range effects on the neurobehavioral development of the progeny. Participants were 139 women with diabetes in pregnancy and their singleton offspring. Serial estimates of circulating maternal fuels were obtained for each pregnancy, along with detailed records of perinatal course and outcome. Offspring were administered the Wechsler Intelligence Scale for Children--Revised (WISC-R) and Kaufman Test of Educational Achievement: Short Form (KTEA) at ages 7 to 11 years. The rate of WISC-R full-scale IQ scores below 70 in our cohort did not differ significantly from national estimates. Nonetheless, after statistically controlling for other influences, WISC-R verbal, performance, and full-scale IQ scores, and Bannatyne's indices of Verbal Conceptualization Ability, Acquired knowledge, Spatial Ability, and Sequencing Ability were inversely correlated with measures of maternal lipid and glucose metabolism in the second and third trimesters. KTEA Arithmetic scores were similarly correlated with measures of maternal lipids in the third trimester. All correlations indicate that poorer maternal metabolic regulation was attended by poorer child performance. The effects of maternal metabolism on fetal brain and neurobehavioral development are discussed as potential intermediary factors.

Child↗

PubMed1998

Expression and function of the type 3 complement receptor in tissues of the developing mouse.

Macrophage (Mphi) expression of the leukocyte integrins has been implicated in their adhesion and migration in the adult. Little is known, however, of the expression or function of these molecules during development. This study defines the spatial and temporal sequences of expression of the type 3 complement receptor (CR3) in the developing mouse; establishes the functional efficacy of this molecule in spreading, adhesion, and phagocytosis; and investigates its role in inflammatory and constitutive migration. Expression of CR3 on monocytes occurred early compared to Mphi-restricted glycoprotein F4/80, but expression on stellate tissue Mphi appeared later than F4/80 and was transient. Expression of CR3 on resident tissue Mphi is more widespread during development, being retained on only very specific Mphi populations in the adult. Neutrophil polymorphs expressed CR3 from day 17 of gestation onward. The anti-CR3 mAb 5C6 was used to investigate the role of CR3 in adhesion, spreading, and phagocytosis by neonatal Mphi. Neonatal macrophages were found to adhere, spread, and phagocytose by CR3-dependent mechanisms, and a CR3-independent system was implicated in the spreading of neonatal Mphi. The role of CR3 in migration during development was then investigated. 5C6 had potent effects on the early stages of the migration of myelomonocytic cells to an inflammatory stimulus in vivo. Despite efficient transplacental transfer of the Ab from pregnant mother to fetus, the process by which monocytes generate populations of resident tissue Mphi was undisrupted, indicating the existence of CR3-independent mechanisms of monocyte migration during development.

Animals↗

PubMed1998

[Locally advanced breast tumors. Role of magnetic resonance in the assessment of response to preoperative therapy and of neoplastic residue before the operation].

INTRODUCTION AND PURPOSE: Induction chemotherapy is the preoperative treatment for locally advanced breast carcinoma. The patients affected with this kind of tumor were previously considered inoperable. The sequential use of different cytotoxic drugs reduces the tumor mass effectively, thus allowing resection and improving patients prognosis. Tumor debulking is at times so significant that conservative treatment can even be considered. A reliable assessment of the response to drug therapy by conventional diagnostic procedures is usually hindered by chemotherapy-induced fibrosis. Magnetic resonance imaging (MRI) is a better tool for distinguishing fibrosis from still vascularized pathologic tissue and thus permits more accurate evaluation of tumor response to chemotherapy, namely tumor debulking and residual viability. MATERIAL AND METHODS: We selected 27 patients with breast cancer and submitted them to MRI both before and after chemotherapy. All examinations were performed with a high field system using 3D Flash sequences with optimized spatial and temporal resolution. RESULTS AND DISCUSSION: The morphologic and dynamic parameters of MRI were in agreement with pathologic findings. In case of persistent disease after chemotherapy, MRI demonstrated increased contrast agent uptake at restaging, with dynamic curves indicating early and intense uptake. In case of marked post-chemotherapy changes, the dynamic curves had a shorter and less steep trend. Finally, when no or very little (few microns) tumor tissue was left, MRI showed no uptake. CONCLUSIONS: Our initial experience indicates MRI as a valid too for monitoring chemotherapy response in breast cancer patients.

Adult↗

PubMed2005

Universal 1/f noise, crossovers of scaling exponents, and chromosome-specific patterns of guanine-cytosine content in DNA sequences of the human genome.

Spatial fluctuations of guanine and cytosine base content (GC%) are studied by spectral analysis for the complete set of human genomic DNA sequences. We find that (i) 1/ f(alpha) decay is universally observed in the power spectra of all 24 chromosomes, and (ii) the exponent alpha approximately 1 extends to about 10(7) bases, one order of magnitude longer than has previously been observed. We further find that (iii) almost all human chromosomes exhibit a crossover from alpha(1) approximately 1 (1/ f (alpha(1))) at lower frequency to alpha(2) <1 (1/ f (alpha(2))) at higher frequency, typically occurring at around 30,000-100,000 bases, while (iv) the crossover in this frequency range is virtually absent in human chromosome 22. In addition to the universal 1/ f(alpha) noise in power spectra, we find (v) several lines of evidence for chromosome-specific correlation structures, including a 500,000 base long oscillation in human chromosome 21. The universal 1/ f(alpha) spectrum in the human genome is further substantiated by a resistance to reduction in variance of guanine and cytosine content when the window size is increased.

Base Composition↗

PubMed2005

Magnetic resonance imaging of the body trunk using a single-slab, 3-dimensional, T2-weighted turbo-spin-echo sequence with high sampling efficiency (SPACE) for high spatial resolution imaging: initial clinical experiences.

PURPOSE: The authors conducted a clinical evaluation of single-slab, 3-dimensional, T2-weighted turbo-spin-echo (TSE) with high sampling efficiency (SPACE) for high isotropic body imaging with large field-of-view (FoV). MATERIALS AND METHODS: Fifty patients were examined in clinical routine with SPACE (regions of interest: pelvis n=30, lower spine n=12, upper spine n=6, extremities n=4) at 1.5 T. For achieving a high sampling efficiency, parallel imaging, high turbofactor, and magnetization restore pulses were used. In contrast to a conventional TSE imaging technique with constant flip angle refocusing, the refocusing pulse train of the SPACE sequence consists of variable flip angle radiofrequency pulses along the echo train. RESULTS: Signal-to-noise ratio and contrast-to-noise ratio of SPACE images were of sufficient diagnostic value. The possibility of image reconstruction in multiple planes was of clinical relevance in all cases and simplified data analysis. CONCLUSION: The achievement of 3-dimensional, T2-weighted TSE magnetic resonance imaging with isotropic and high spatial resolution and interactive 3-dimensional visualization essentially improve the diagnostic potential of magnetic resonance imaging.

Abdominal Neoplasms↗

PubMed2006

Optimization of cardiac cine in the rat on a clinical 1.5-T MR system.

OBJECT: The overall goal was to study cardiovascular function in small animals using a clinical 1.5-T MR scanner optimizing a fast gradient-echo cine sequence to obtain high spatial and temporal resolution. MATERIALS AND METHODS: Normal rat hearts (n = 9) were imaged using a 1.5-T MR scanner with a spiral fast gradient-echo (fast field echo for Philips scanners) sequence, three Cartesian fast gradient-echo (turbo field echo for Philips scanners) sequences with different in-plane resolution, and with and without flow compensation and half-Fourier acquisition. The hearts of four rats were then excised and left-ventricle mass was weighed. Inter- and intra-observer variability analysis was performed for magnetic resonance imaging (MRI) measurements. RESULTS: Half-Fourier acquisition with flow compensation gave the best sequence in terms of image quality, spatial as well as temporal resolution, and suppression of flow artifact. Ejection fraction was 71 +/- 4% with less than 5% inter- and intra-observer variability. A good correlation was found between MRI-calculated left-ventricular mass and wet weight. CONCLUSIONS: Using optimized sequences on a clinical 1.5-T MR scanner can provide accurate quantification of cardiac function in small animals and can promote cardiovascular research on small animals at 1.5-T.

Algorithms↗

PubMed2006

The impact of path crossing on visuo-spatial serial memory: encoding or rehearsal effect?

The determinants of visuo-spatial serial memory have been the object of little research, despite early evidence that not all sequences are equally remembered. Recently, empirical evidence was reported indicating that the complexity of the path formed by the to-be-remembered locations impacted on recall performance, defined for example by the presence of crossings in the path formed by successive locations (Parmentier, Elford, & Maybery, 2005). In this study, we examined whether this effect reflects rehearsal or encoding processes. We examined the effect of a retention interval and spatial interference on the ordered recall of spatial sequences with and without path crossings. Path crossings decreased recall performance, as did a retention interval. In line with the encoding hypothesis, but in contrast with the rehearsal hypothesis, the effect of crossing was not affected by the retention interval nor by tapping. The possible nature of the impact of path crossing on encoding mechanisms is discussed.

Analysis of Variance↗

PubMed2002

Local mean normalization of microarray element signal intensities across an array surface: quality control and correction of spatially systematic artifacts.

Here we present a methodology for the normalization of element signal intensities to a mean intensity calculated locally across the surface of a DNA microarray. These methods allow the detection and/or correction of spatially systematic artifacts in microarray data. These include artifacts that can be introduced during the robotic printing, hybridization, washing, or imaging of microarrays. Using array element signal intensities alone, this local mean normalization process can correct for such artifacts because they vary across the surface of the array. The local mean normalization can be usedfor quality control and data correction purposes in the analysis of microarray data. These algorithms assume that array elements are not spatially ordered with regard to sequence or biological function and require that this spatial mapping is identical between the two sets of intensities to be compared. The tool described in this report was developed in the R statistical language and is freely available on the Internet as part of a larger gene expression analysis package. This Web implementation is interactive and user-friendly and allows the easy use of the local mean normalization tool described here, without programming expertise or downloading of additional software.

Algorithms↗

PubMed2004

Spatially directed movement and neuronal activity in freely moving monkey.

The abilities to plan a series of movements and to navigate within the environment require the functions of the frontal and ventromedial temporal lobes, respectively. Neuropsychological studies posit the existence of egocentric (prefrontal) and allocentric (ventromedial temporal) spatial frames of reference that mediate these functions. To examine neural mechanisms underlying egocentric and allocentric guidance of movement, we have developed behavioral and neurophysiological techniques for freely moving monkey. In this chapter, we provide evidence that the dorsolateral prefrontal cortex is important for egocentric spatial tasks in both the visual and tactile modalities, but it does not contribute to performance of an allocentric spatial task. Moreover, neurophysiological recordings indicate that prefrontal neurons are involved in monitoring the spatial nature of behavioral sequences in an egocentric memory task. In contrast, hippocampal neurons are active during spatially directed locomotion, apparently reflecting the monkey's location in a testing room. This discharge is independent of the task's contingencies.

Animals↗

PubMed2004

Conformation-dependent sequence design: evolutionary approach.

A new modification of evolutionary approach to sequence design of copolymers has been proposed. A model of step-by-step evolution of a two-letter ( HP) copolymer sequence has been studied by means of a coarse-grained Monte Carlo algorithm. The conditions for accepting a change in the primary sequence depend on the spatial conformation of HP-copolymer chain. This leads to a coupling between sequence and conformation and to formation of protein-like conformations and primary sequences (for some values of parameters of the model) independently of initial sequence and/or conformation. Simple theory describing these computer simulation observations is developed.

Algorithms↗

PubMed2001

Evaluation of the anatomical and functional properties of deglutition with various kinetic high-speed MRI sequences.

We evaluated various fast MR sequences for obtaining anatomical and dynamic functional information during deglutition. Seven healthy volunteers underwent MRI of the oropharynx during swallowing of an oral positive-contrast agent. Single-slice imaging was performed in the median sagittal plane while subjects were in a supine position. Twenty serial images were obtained using EPI, FLASH, and turbo-FLASH sequences. The dynamic (movement-related) information and the anatomical resolution of the soft tissues were evaluated during deglutition. The FLASH sequence provided high-quality images at rest. During swallowing, however, the images were significantly degraded by movement artifacts and had inferior temporal resolution. The EPI evidenced better temporal resolution, but was degraded by strong distortions and movement artifacts. The turbo-FLASH sequence provided the best temporal resolution and sufficient spatial resolution during motion. This sequence proved optimal for the investigation of swallowing function, and is expected to be of value for the documentation of functional disturbances in patients with oropharyngeal pathology.

Deglutition↗