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At least 1,441 records · Page 80Linked to original sources
PubMed2000

Computer driven needle probe enables therapy for painful neuropathies.

Recent integration of spatial localization equipment with imaging systems presents more precise methods for the delivery of deep body nerve blocks. This technology builds on the already accepted use of CT as a guide for many currently used nerve blocks by delivering improved control, precision, and visualization of needle placement. This paper discusses the improvements and possibilities this technology brings to the treatment of neuropathies.

Biopsy, Needle↗
PubMed2001

MR spectroscopy in pediatric neuroradiology.

MR spectroscopy of the pediatric brain now has entered the clinical arena as a result of enhanced technology, complementary new sequences, and proof of clinical utility. Armed with a knowledge of the variation in metabolite concentrations over time, with myelination and brain growth, proton MR spectroscopy can be helpful in differential diagnosis, management, and prognostication of pediatric disease processes. Although other molecules can be interrogated, hydrogen proton spectroscopy is the mainstay. The development of multiplanar techniques, performed in a time-efficient fashion, has enabled more robust spectra to be obtained from larger volumes of brain, permitting spatial localization of different metabolites, such as lactate. With the introduction of gene therapy and other new interventions, a noninvasive tool such as MR spectroscopy may prove to be invaluable.

Brain↗
PubMed2001

[Morphofunctional characteristics of cell death in the epidermis in gunshot damage to rat skin under experimental conditions].

Different types epidermocyte death were considered in a model of skin gunshot injury in albino rats, Using light microscopy, cytophotometry and immunocytochemistry. Epidermocyte death was characterized by various morphological changes of nuclei, spatial localization of dying cells and different intensity of cellular death, that was registered in all the experimental terms. Cell alterations of necrotic, oncotic and apoptotic types were observed. Oncotic and necrotic type keratinocyte death prevailed in early and middle stages of regenerative histogenesis due to structural and metabolic organic disorders in the skin: in later stages distinctly manifested apoptotic cell death is more possible. However it is more probable that the majority of such cells completes their cycle with necrosis. This is connected to the fact that apoptosis is an energy-dependent process as caspase-activating adapter proteins contact with mitochondrial membranes. Gunshot injury had likely caused definite changes in molecular mechanisms of proliferative processes regulation, cell differentiation and death, leading to accumulation of pathologically altered cells in the epidermis.

Animals↗
PubMed2001

Neuroradiologic findings in focal cortical dysplasia: histologic correlation with surgically resected specimens.

PURPOSE: We investigated the neuroradiologic characteristics of focal findings of surgically resected specimens obtained from 47 patients with focal cortical dysplasia (FCD). METHODS: Forty cases were detected by magnetic resonance imaging (MRI), and two cases were detected only by single-photon emission computed tomography (SPECT), but five cases could not be detected before operation. RESULTS: MRI revealed abnormal gyri and sulci in 34 patients (pachygyric in 18, polymicrogyric in 10, both in six), and blurring of the gray matter-white matter junction in 29 (72%) patients. Signal abnormalities were found in 36 (90%) patients, in the gray matter in 32, with white matter in 30, and at the gray matter-white matter junction in 13. Moreover, peculiar patterns of abnormal signals in the white matter were recognized, including remarkably abnormal subcortical signals of T2 hyperintensity and T1 hypointensity adjacent to the dysplastic cortex in 15 cases, high radiated T2 signals extending from the ependymal surface of the lateral ventricle to the overlying cortex in 11 cases, and widespread abnormal signals in the white matter with gray matter involvement in four cases. Histologically, these abnormal signals corresponded to various degrees of dyslamination and morphologic abnormalities of neurons and glial cells in the gray matter, and to dysmyelination, ectopic clustering of dysplastic neurons, glial proliferation, and necrotic change in the white matter. Regional cerebral blood flow SPECT showed interictal hypoperfusion in 29 (62%) of the 47 patients, interictal hyperperfusion in two, and ictal hyperperfusion in 28 of the 34 patients associated with FCD. [123I]iomazenil SPECT demonstrating the distribution of central benzodiazepine receptors showed low accumulations localized spatially corresponding to the epileptogenic foci associated with FCD in seven of eight patients. CONCLUSIONS: These results demonstrate that neuroimaging reflects various structural and functional changes closely related to epileptogenesis in FCD.

Adolescent↗
PubMed2001

Maturation of pig oocytes in vivo and in vitro.

In this review the concept that the origins of embryonic failure occur during oocyte development is explored. The four factors that determine oocyte viability, namely a normal growth phase, adequate follicle cell support during maturation, the completion of intracellular reprogramming before fertilization and the functioning of oocyte surveillance mechanisms, form the four sections of this review. The viability of pig oocytes at the end of the growth phase is compromised by presumptive spontaneous meiotic progression and by morphological heterogeneity. Determining the percentage and identity of viable dictyate oocytes, and identifying the reasons for the loss of viability, are key areas of future investigation. Although the requirement for follicle cell support during maturation is already established, little is yet known about the underlying signals and their transmission to the oocyte. The analysis of the action and nature of somatic signals will provide the foundation for further advances in the maturation of oocytes in vitro. Signalling cascades in oocytes control both the translation of masked mRNA and the modification and spatial localization of resultant proteins. The interdependent nature of this control system explains why inappropriate signals during maturation lead to subsequent embryonic mortality. Chromosomal errors during meiosis and early mitosis accumulate because of the leaky nature of the checkpoint system during the maternally regulated part of development: effective cell cycle surveillance is established only after the activation of the embryonic genome. In summary, we emphasize that the quality of the dictyate oocyte and the provision of appropriate signals in vitro are the principal determinants of maturational success.

Animals↗
PubMedDate not supplied

[Integral characteristics of the cardiac electrical excitation wave].

A set of characterisitics of the cardiac electrical generator is described which expresses in an integral form some important properties of the electrical excitation wave, in particular its summary intensity, average spatial localization and distinction from a uniform double layer with planar rim. Relation of the proposed model to the multipole equivalent generator is discussed, and procedures for computing its characteristics are given. Calculation results for these characteristics on the basis of experimentally measured electrical field potentials of isolated dog hearts are presented.

Heart Conduction System↗
PubMed2002

Visual perceptual functions predict instrumental activities of daily living in patients with dementia.

OBJECTIVE: To assess relations between discrete visual perceptual functions commonly affected in patients with neurodegenerative dementia and the performance of instrumental activities of daily living (IADL). BACKGROUND: Neuropsychologic measures are often used to predict IADL performances in dementia patients. Prior studies have focused on the contribution of higher-level memory and executive deficits to IADL. The relation between visuoperceptual dysfunction and IADL has not been studied systematically. METHODS: Thirty-five elderly patients with neurodegenerative disorders, most diagnosed with probable Alzheimer disease, participated. Patients completed tasks tapping visual perceptual functions believed to be mediated by occipital lobe structures (shape discrimination), posterior inferotemporal regions (face, object form, and written word discrimination), and the dorsolateral parietal lobe (spatial localization). A knowledgeable caregiver rated IADL performance. RESULTS: Object form discrimination, but not other visual perceptual functions, correlated significantly ( = 0.60) with performances of visually based IADL (e.g., misjudging distances, driving, and recognizing familiar people), but not with other IADL, when the variance attributable to dementia severity, language disturbance, and other visual perceptual abilities was controlled. CONCLUSIONS: In contrast to prior investigations that have focused primarily on relations of memory and executive control deficits with IADL in neurologically impaired patients, the results of this study highlight the important contribution of bilateral inferotemporal visual perceptual systems for the performance of IADL in elderly patients with neurodegenerative dementia.

Activities of Daily Living↗
PubMed2002

[Technique of intraoperative planning in prostatic brachytherapy with permanent implants of 125I or 103Pd].

OBJECTIVES: Prostatic brachytherapy with permanent 125I or 123Pd seeds implantation is a therapeutic option for organ-confined prostate cancer. We analyze the technique based on previous planning, our current intraoperative planning procedure and the reasons that moved us to introduce this change. METHODS: Changes in prostate volume and spatial localization observed between previous planning and intraoperative images, and possible difficulties for seed implantation due to pubic arch interference are some of the reasons that induce us to change technique. RESULTS: Before the operation, we calculate the prostatic volume by transrectal ultrasound; with this information we determine the total implant activity following Wu's nomogram, and per-seed activity; therefore, it is an individual process for each patient. We perform a peripheral implant, placing 75-80% of the seeds within the peripheral prostatic zone, generally through 12-15 needles, the rest of the seeds are placed in the central prostatic zone using a maximum of 3-4 needles in high volume prostates. The day of intervention, after positioning and catheter insertion, volumetry is re-checked. Ultrasound images (from base to apex every 5 mm) are transferred to the planner were a suitable seed distribution is determined. Implantation is then performed placing all needles unloaded, and then intraoperative post-planning to allow us to check implant precision is performed after cistoscopically check that there is no urethral or bladder penetration by any needle. We finish with the insertion of seeds into the prostate. Total time for the procedure is around 90 minutes. CONCLUSIONS: Intraoperative planning is an additional step for the treatment of prostate cancer with permanent seeds brachytherapy, which avoids the disadvantages of previous planning and improves tumor inclusion in the ideal irradiation dose area, which will translate into better local disease control.

Brachytherapy↗
PubMed2003

An introduction to bio-inspired artificial neural network architectures.

In this introduction to artificial neural networks we attempt to give an overview of the most important types of neural networks employed in engineering and explain shortly how they operate and also how they relate to biological neural networks. The focus will mainly be on bio-inspired artificial neural network architectures and specifically to neo-perceptions. The latter belong to the family of convolutional neural networks. Their topology is somewhat similar to the one of the human visual cortex and they are based on receptive fields that allow, in combination with sub-sampling layers, for an improved robustness with regard to local spatial distortions. We demonstrate the application of artificial neural networks to face analysis--a domain we human beings are particularly good at, yet which poses great difficulties for digital computers running deterministic software programs.

Animals↗
PubMed2003

Calcium dependence of retrograde inhibition by endocannabinoids at synapses onto Purkinje cells.

Many types of neurons release endocannabinoids from their dendrites in response to elevation of intracellular calcium levels. Endocannabinoids then activate presynaptic cannabinoid receptors, thereby inhibiting neurotransmitter release for tens of seconds. A crucial step in understanding the physiological role of this retrograde signaling is to determine its sensitivity to elevations of postsynaptic calcium. Here we determine and compare the calcium dependence of endocannabinoid-mediated retrograde inhibition at three types of synapses onto cerebellar Purkinje cells. Previous studies have shown that Purkinje cell depolarization results in endocannabinoid-mediated retrograde inhibition of synapses received from climbing fibers, granule cell parallel fibers, and inhibitory interneurons. Using several calcium indicators with a range of affinities, we performed a series of in situ and in vitro calibrations to quantify calcium levels in Purkinje cells. We found that postsynaptic calcium levels of approximately 15 microM are required for half-maximal retrograde inhibition at all of these synapses. In contrast, previous studies had suggested that endocannabinoid release could occur with slight elevations of calcium above resting levels, which implies that inhibition should be widespread and continuously modulated by subtle changes in intracellular calcium levels. However, our results indicate that such small changes in intracellular calcium are not sufficient to evoke endocannabinoid release. Instead, because of its high requirement for calcium, retrograde inhibition mediated by calcium-dependent endocannabinoid release from Purkinje cells will occur under more restricted conditions and with greater spatial localization than previously appreciated.

Animals↗
PubMed1992

[Ca2+]i effects of bradykinin B2 receptor activation in PC12 cells.

In PC12 cells, activation of B2 receptors by bradykinin promotes an elevation of cytosolic Ca2+ by two mechanisms: IP3 mediated release of Ca2+ from intracellular stores and stimulation of multiple Ca2+ influx pathways. Since these events can have different kinetics and spatial localizations they can induce diversified effects in different cell areas.

Adenosine Triphosphate↗
PubMed1992

Effects of tumor necrosis factor, lipopolysaccharide, and IL-4 on the expression of vascular cell adhesion molecule-1 in vivo. Correlation with CD3+ T cell infiltration.

We have injected human TNF, LPS, and IL-4 into the skin of baboons to examine regulation of endothelial leukocyte adhesion molecules (ELAM) in vivo and to determine which endothelial adhesion molecules correlate temporally and spatially with cytokine-induced T cell infiltration. The expression of adhesion molecules ELAM-1 (E-selectin), VCAM-1, and ICAM-1 (CD54) were quantified by immunocytochemical staining of frozen sections obtained from skin biopsies; T cell infiltration was measured by immunocytochemical staining of CD3+ T cells in serial sections. We found that injection of TNF causes late (24 to 48 h) T cell infiltration whereas injection of LPS, in doses that do not cause tissue necrosis, does not. The ability of TNF (but not LPS) to recruit T cells correlates with the ability of TNF to cause sustained endothelial cell adhesion molecule expression. Expression of VCAM-1 on post-capillary venules showed the highest degree of spatial localization with infiltrates. IL-4, although not proinflammatory by itself, can cause T cell infiltration in combination with an ineffective dose of TNF. The ability of IL-4 to augment TNF-induced inflammation best correlates with the ability of the combination of IL-4 and TNF to increase endothelial VCAM-1 expression. In contrast, IL-4 does not promote T cell infiltration or endothelial VCAM-1 expression in combination with LPS. In cytokine-injected tissues, VCAM-1 is also expressed on connective tissue cells other than endothelium, including smooth muscle and perineural cells, where it is induced by cytokines in parallel with endothelial VCAM-1. Overall, our data support the hypothesis that endothelial VCAM-1 expression contributes to T cell extravasation at sites of inflammation. Furthermore, we find that IL-4, a product a Ag-activated T cells, can interact with TNF to selectively promote VCAM-1 expression and the development of T cell-rich infiltrates, characteristic of Ag-induced inflammatory reactions.

Animals↗
PubMed1992

Forebrain norepinephrine: role in controlled information processing in the rat.

A series of experiments examined the effects of 6-hydroxydopamine (6-OHDA)-induced depletion of forebrain norepinephrine (NE) on the performance of a visual detection (spatial localization) task. The behavioral paradigm used was an analogue of Leonard's 5-choice serial reaction time task for humans. The 6-OHDA lesion of the dorsal noradrenergic bundle (DNAB) produced a 98% depletion of the NE content in the neocortex, and a much smaller depletion (32%) of the NE content in the hypothalamus. As reported previously, performance of visual discrimination was unaffected by DNAB lesions, even when the discrimination was made more difficult by decreasing the intensity of the visual stimuli. However, the lesion produced a significant decrease in accuracy and a significant increase in omissions when a burst of loud white noise was presented just prior to the onset of the visual discriminanda. Similarly, a significant decrease in discriminative accuracy was produced in the rats with forebrain NE depletion by systemic administration of the psychomotor stimulant, d-amphetamine (0.2 to 0.8 mg/kg). In both of these experiments, the lesion-induced discrimination impairment was not magnified by reducing the brightness of the visual discriminanda, suggesting that the behavioral impairment was not caused by a decreased ability to detect the visual stimuli. In addition, the lesion impaired discriminative accuracy when the visual discriminanda were presented at an unpredictable rate. The implications of these behavioral impairments produced by forebrain NE depletion for theories of catecholamine involvement in attentional processes and arousal are discussed in terms of a possible role for the DNAB in controlled or "effortful" processing.

Acoustic Stimulation↗
PubMed2001

Intramolecular carbohydrate-protein interaction.

In this report, an overview is presented of studies on the three-dimensional structure in solution of glycoproteins. The investigations were carried out by using high resolution NMR spectroscopy in conjunction with molecular dynamics calculations and molecular modelling. For pine apple stem bromelain, ribonuclease 2 and the free alpha-subunit of human chorionic gonadotropin it could be shown that intramolecular interactions between carbohydrate and protein exist. Glycosylation sites are rather unique structural entities in glycoproteins, because of the local spatial arrangements. This is reflected in different intramolecular interactions between carbohydrate and protein.

Amino Acid Sequence↗
PubMedDate not supplied

[Rat behavior in a light/dark chamber: place preference task].

After a 6-week social isolation (from 22nd to 70th day from birth) male Wistar rats (a sibship, 10 animals), were tested for 20 min in a light/dark box in order to reveal behavioral features of choice of their spatial localization in unknown conditions. Socially deprived rats significantly differed from control animals in longer time of the room choice, higher number of entries of the light section, and higher number of rearings, which was probably explained by their higher anxiety and lack of experience to estimate unexpected stimuli and select a response. The mean level of behavioral activity during exploration of the box defined by the number of elementary operations per minute remained constant and was significantly higher in the socially deprived rats than in the control animals.

Animals↗
PubMed2005

Toward modeling regionally specific human security using GIS: case study Cambodia.

A new methodology for measuring human security is presented. The three stages of the methodology are: i) threat assessment, ii) data collection and organization, and iii) data visualization and analysis, using Geographic Information Systems. Results from a Cambodia case study are highlighted. The United Nations Development Program's notion of human security, which gives equal weight to economic, health, food, political, personal, and environmental factors, is used. Country-specific threats in each category are determined, and local, spatially referenced data are collected. In this paper, poverty, dengue fever, and tuberculosis are used as examples of the analytic process. Regions of Cambodia exposed to all three of these threats ("hot spots") are located, and spatial correlation between poverty, dengue fever, and tuberculosis is calculated. The methodology i) advances a broad concept of human security, ii) will potentially assist policy and decision makers, and iii) identifies research questions that cannot be resolved using single-sector analysis.

Cambodia↗
PubMed2005

[Effects of high potassium solutions and caffeine on the processes of exo-endocytosis of synaptic vesicles at the frog motor nerve ending].

In experiments on the frog motor nerve endings of cutaneous pectoris muscle using fluorescent microscopy it has been shown that initiation of massive transmitter release of synaptic vesicles by high potassium solutions in using endocytotic marker FM 1-43 at the nerve terminals light spots occurred only at some of the nerve terminals or at the some parts of nerve terminal. It has been revealed that application of caffeine increased the number of light terminals. Using extracellular microelectrode recording, we showed that both high potassium solutions and caffeine increased frequency of miniature end-plate potentials in a dose-dependent manner. However, high potassium solutions always increased the frequency of spontaneous transmitter release while caffeine increased it only in some experiments. It was concluded that processes of exo- and endocytosis can be caused both by entry of Ca ions at the nerve ending during depolarization (high potassium solutions) and by Ca release from endoplasmic reticulum (caffeine). Possible spatial localization of endoplasmic reticulum at the motor nerve ending is discussed. The hypothesis of its role at the remodeling of synapse was proposed.

Animals↗
PubMed1992

Cardiac magnetic resonance spectroscopy.

Magnetic resonance spectroscopy provides information about metabolic processes in living tissues. The resulting information may be more sensitive and specific than that obtained using techniques that rely on functional or structural measurements. Although the preponderance of applications to date have been in physiologic investigations in animals, clinical applications are emerging. Reports in the past two years have appeared evaluating the clinical use of phosphorus spectroscopy to detect ischemic heart disease, cardiomyopathy, and cardiac transplant rejection. Active research using nuclei other than phosphorus for spectroscopy will expand the potential clinical applications. Technical developments, including improved surface coil design, wider use of high-field magnets and new pulse sequences, will allow improved sensitivity and spatial localization in the future.

Animals↗