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PubMed1996

Organization of excitatory and inhibitory local networks in the caudal nucleus of tractus solitarius of rats revealed in in vitro slice preparation.

Morphological and physiological properties of neurons in the caudal nucleus of tractus solitarius (NTS) of rats were studied in vitro by whole-cell recording and intracellular staining with biocytin. Synaptic responses following the solitary tract stimulation were also investigated to elucidate anatomical substrates of the underlying local circuits. Biocytin-filled NTS cells were divided into three groups according to the pattern of their axonal arborization: (1) local circuit neurons whose axon collaterals were extensively distributed within the NTS with the main axons leaving the NTS; (2) presumed interneurons whose axon collaterals seemed to be restricted within the NTS; and (3) projection neurons whose axons had few, if any, collaterals. Both local circuit neurons and presumed interneurons had small cell bodies (< 150 microns2 in somal area) and exhibited tonic regular spiking at depolarized membrane potentials. Polysynaptic excitatory background activity was increased and lasted for 300-1000 msec in these neurons following solitary tract stimulation. The projection neurons had medium to large cell bodies (> 150 microns2 in somal area). Inhibitory postsynaptic responses produced by an increased CI-conductance were recorded in these projection neurons. These findings suggest that excitatory local networks are organized by an assembly of the local circuit neurons in the caudal NTS, and that the interneurons are arranged to connect the excitatory local network with medium to large projection neurons via inhibitory synapses. Visceral afferent information is probably processed in the highly organized excitatory and inhibitory local networks within the caudal NTS and conveyed to other brain regions.

Afferent Pathways↗
PubMed2002

Ethnic identities, social capital and health inequalities: factors shaping African-Caribbean participation in local community networks in the UK.

This paper examines the impact of ethnic identity on the likelihood of peoples' participation in local community networks, in the context of recent policy emphasis on the participation of marginalised communities in such networks as a means of reducing health inequalities. Conceptually, the paper is located against the background of debates about possible links between health and social capital--defined in terms of grassroots participation in local community networks--and an interest in the way in which social exclusion impacts on social capital. The paper draws on lengthy semi-structured, open-ended interviews with 25 African-Caribbean residents of a deprived multi-ethnic area of a south England town. While African-Caribbean identity played a central role in peoples' participation in inter-personal networks, this inter-personal solidarity did not serve to unite people at the local community level beyond particular face-to-face networks. Levels of participation in voluntary organisations and community activist networks were low. Informants regarded this lack of African-Caribbean unity within the local community as a problem, saying that it placed African-Caribbean people at a distinct disadvantage--furthering their social exclusion through limiting their access to various local community resources. The paper examines the way in which the construction of ethnic identities--within a context of institutionalised racism at both the material and symbolic levels--makes it unlikely that people will view local community organisations or networks as representative of their interests or needs, or be motivated to participate in them. Our findings highlight the limitations of policies which simply call for increased community participation by socially excluded groups, in the absence of specific measures to address the obstacles that stand in the way of such participation.

Adolescent↗
PubMed1994

Electronic document delivery using the Internet.

The Health Sciences Libraries Consortium (HSLC) was established in 1985 by thirteen founding member institutions in Pennsylvania and Delaware. In 1989, the Interlibrary Loan, Document Delivery, and Union List Task Force, appointed by the HSLC Board of Directors, successfully demonstrated the feasibility of supplying 94% of all interlibrary loan (ILL) photocopy requests in forty-eight hours or less by a network application of group 3-level memory telefacsimiles. However, the expenses associated with the telefacsimile operation and the limitations associated with network polling protocols challenged participants to seek new alternatives for ILL. In 1990, the HSLC introduced HSLC HealthNET, an online wide-area network linking eleven of the thirteen institutions and their resources while providing access to the Internet. The HSLC HealthNET additionally supports a centralized shared library system, several locally mounted databases, and consortiumwide electronic mail. In 1991, a project was initiated to evaluate Ariel software, pioneered by the Research Libraries Group (RLG), compared to the existing network application of group 3-level telefacsimiles. Factors identified as critical to Ariel's potential to replace the telefacsimile network were the proprietary software specifications for Internet access, the use of HSLC's existing wide-area network (WAN), and a hardware platform that was optimal for an ILL environment. This article describes the Ariel project history, the transition to Ariel from the telefacsimile network, evaluation of equipment features for processing efficiency, and operational issues affecting ILL policy.

Computer Communication Networks↗
PubMedDate not supplied

[Tridimensional evaluation model of health promotion in school -- a proposition].

A good school health programme can be one of the most cost effective investments for simultaneously improving education and health. The general direction of WHO's European Network of Health Promoting Schools and Global Schools Health Initiative is guided by the holistic approach and the Ottawa Charter for Health Promotion (1986). A health promoting school strives to improve the health and well-being of school pupils as well as school personnel, families and community members; and works with community leaders to help them understand how the community contributes to health and education. Evaluation research is essential to describe the nature and effectiveness of school health promoting activity. The overall aim of this paper is to help school leaders and health promotion coordinators to measure their work well and effectively. The specific aim is to offer a practical three-dimensional evaluation model for health promoting schools. The material is presented in two sections. The first one is a 'theoretical base' for health promotion which was identified from broad based daily health promotion practical activities, strategies and intersectional interventions closely related to the philosophy of the holistic approach. The three dimensions refer to: 1. 'areas' -- according to the mandala of health. 2. 'actions' -- according to Ottawa Charter strategies which should be adapted to the local school networks. 3. 'data'-- according to different groups of evidence (process, changes and progress). The second one, as a result of the mentioned base, represents the three 'core elements': standards, criteria and indicators. In conclusion, this article provides a practical answer to the dilemma of the evaluation model in the network of local school environment. This proposition is addressed to school staff and school health promotion providers to make their work as effective as possible to improve pupils health. Health promoting school can be characterized as a school constantly strengthening its capacity as a healthy setting for learning and working. But only proper documentation of progress and evidence base procedures related to local networks can prove the constructive work of people and create progress and partners for the development of health in schools.

Child↗
PubMed1981

Endemic occurrence of Mycobacterium kansasii in water-supply systems.

Of a total number of 1079 drinking water and colliery service water samples examined in an area of the North-Moravian Region Czechoslovakia, characterized by endemic occurrence of M. kansasii infections, 233 [21.6%] samples were found to be contaminated by mycobacteria, of these 20 [1.9%] by M. kansasii. Of additionally examined 510 water samples from the municipal water-supply network, which were collected in hospital laboratories and clinical departments as well as in the households of patients with M. kansasii infection and their possible contacts, 171 [33.5%] samples showed presence of mycobacteria, of these 18 [3.5%] were M. kansasii-positive. This mycobacterial species was isolated from the drinking water samples collected in two hospitals in the core of the endemic area, e.i. in the district of Karviná. In the district of Ostrava, where the drinking water supply, bot for colliery and households facilities, is provided from the same water-supply system, the presence of M. kansasii in the municipal water-supply network was not proved, but it was isolated from 5 samples of colliery drinking water. Further 114 samples taken from the local water treatment plant supplying the endemic area with drinking water were found to be free of M. kansasii species.

Czechoslovakia↗
PubMedDate not supplied

[Experience with a local health system in Santa Cruz, Bolivia].

In 1988 the health care network in Bolivia had 80 health districts, of which 18 were urban and 62 were rural. The city of Santa Cruz de la Sierra, located in the country's tropical area, was divided into five health districts. One of these was selected for implementation of a local health system, based on four priority criteria: socioeconomic situation, epidemiologic profile, access to health services, and services coverage. After the model had been in place for ten months, significant results could be seen, which are summarized as follows: effective participation by the people in the district, increased demand for preventive services, interest in receiving information and health education, satisfaction on the part of the people with the actions carried out vis-à-vis the perceived needs, and effective coordination of all the institutions making up the local health system.

Bolivia↗
PubMed1997

Exercise by prescription.

General Practitioners (GPs) see over 90% of their practice population in three years. Over 50% of the adult population is below the perceived level of physical activity as recognised by the Allied Dunbar Physical Activity score (Allied Dunbar, Health Education Authority and Sports Council, 1992). Physical fitness levels in adolescents and children are declining, while the incidence of obesity is increasing. GPs, with their Primary Health Care Team, are in a unique position to be able to discuss the health benefits of regular physical activity with their patients during the consultation and offer, if appropriate, a prescription for a course of physical activity to a local leisure centre or community activity centre. Many communities have facilities for physical activity. These include leisure centres, schools, village and church halls, the home and the general practice surgery. A directory of resources for physical activity for all age groups should be available in the surgery waiting room area. A community co-ordinator can network community facilities and resources to meet individual need. The co-ordinator can be funded by the general practice surgery, Health Authority, Local Authority, Parish or District Council. An agreed protocol for exercise prescription referrals to suitable community facilities can benefit patient health care for a variety of medical, surgical, social and mental conditions. Auditing exercise prescriptions shows a health benefit, with improved quality of living and reduced prescription medicines.

Adolescent↗
PubMed1987

Immunoelectronmicroscopic localization of extracellular matrix components produced by bovine corneal endothelial cells in vitro.

Bovine corneal endothelial cells deposit an extracellular matrix in short-term cultures, which contains various morphologically distinct structures when analysed by electron microscopy after negative staining. Amongst these were long-spacing fibers with a 150 nm periodicity, which appeared also to be assembled into more complex hexagonal lattices. Another structure was fine filaments, 10-40 nm in diameter, which occasionally exhibited 67 nm periodic cross-striation. Non-striated 10-20 nm filaments sometimes formed radially oriented bundles arranged in networks and fuzzy granular material was associated with the filaments in the bundles. Often, these bundles extended into solitary filaments, 10-20 nm in diameter, with a smooth surface. In addition, amorphous patches were seen, which contained dense aggregates of fibrillar and granular material. In longer-term cultures, some of the structures coalesced to form large fibrillar bundles. By using specific antibodies to various extracellular matrix components and immunolabeling with gold some of these structures could be identified as to their protein composition. Whereas fibronectin antibodies labeled a variety of structures--fine filaments with granular materials, radially oriented bundles, patchy amorphous aggregates and small granular material scattered throughout the background--type III collagen antibody predominantly labeled filaments with periodic banding (10-40 nm in diameter). A small amount of type III specific labeling was also observed over the networks of radially oriented fibrils and fine filaments associated with granular material. Type IV collagen and laminin antibodies localized in areas of the patchy amorphous aggregates. Type VI collagen antibodies, on the other hand, labeled fine filaments and the gold particles showed a pattern of 100 nm periodicity. Many of the fine 10-20 nm filaments exhibited a tubular appearance on cross-section, but they were not reactive with any of the antibodies used. Also negative were the long-spacing fibers and assemblies--including hexagonal lattices--containing this structural element.

Animals↗
PubMed1985

A calcium requirement for electric field-induced cell shape changes and preferential orientation.

C3H/10T1/2 mouse embryo fibroblasts stimulated by a steady electric field (10 V/cm) for 30 min exhibited lamellar retraction on the sides facing the electrodes. Some cells elongated and preferentially oriented with their long axis perpendicular to the field direction. Depletion of external calcium or blockage of calcium influx with lanthanum or the calcium channel blocker D-600 resulted in a reduction of the field-induced response. When external calcium was elevated stepwise from 0 to 10 mM, the field-induced response increased correspondingly. Electric stimulation in the presence of the calcium ionophore A23187 resulted in an increase of spindle-shaped cells with no preferential orientation. This response was blocked by calcium depletion and lanthanum, but not by D-600. The anticalmodulin drug W-13 inhibited the field-induced responses observed in normal buffer as well as in the presence of A23187. Some cell death resulted from prolonged electric field exposure, and the mortality was reduced by calcium depletion, lanthanum or D-600, but was not affected by W-13. We postulate that local calcium influx through channels opened by the electric field produces areas of high intracellular calcium which stimulate the cytoskeletal network to induce lamellar retraction. Prolonged field-induced calcium influx may eventually overcome the cell's mitochondrial calcium-buffer system, leading to necrotic calcification.

Animals↗
PubMed2002

Quantitative analysis of the dendritic morphology of corticocortical projection neurons in the macaque monkey association cortex.

The polymodal association areas of the primate cerebral cortex are heavily interconnected and play a crucial role in cognition. Area 46 of the prefrontal cortex in non-human primates receives direct inputs from several association areas, among them the cortical regions lining the superior temporal sulcus. We examined whether projection neurons providing such a corticocortical projection differ in their dendritic morphology from pyramidal neurons projecting locally within area 46. Specific sets of corticocortical projection neurons were identified by in vivo retrograde transport in young macaque monkeys. Full dendritic arbors of retrogradely labeled neurons were visualized in brain slices by targeted intracellular injection of Lucifer Yellow, and reconstructed three-dimensionally using computer-assisted morphometry. Total dendritic length, numbers of segments, numbers of spines, and spine density were analyzed in layer III pyramidal neurons forming long projections (from the superior temporal cortex to prefrontal area 46), as well as local projections (within area 46). Sholl analysis was also used to compare the complexity of these two groups of neurons. Our results demonstrate that long corticocortical projection neurons connecting the temporal and prefrontal cortex have longer, more complex dendritic arbors and more spines than pyramidal neurons projecting locally within area 46. The more complex dendritic arborization of such neurons is likely linked to their participation in cortical networks that require extensive convergence of multiple afferents at the cellular level.

Animals↗
PubMed2001

Effects of domain-specific interference on brain activation associated with verbal working memory task performance.

Previous neuroimaging studies have identified brain regions that underlie verbal working memory in humans. According to these studies a phonological store is located in the left inferior parietal cortex, and a complementary subvocal rehearsal mechanism is implemented by mostly left-hemispheric speech areas. In the present functional magnetic resonance imaging study, classical interfering and non-interfering dual-task situations were used to investigate further the neural correlates of verbal working memory. Verbal working memory performance under non-interfering conditions activated Broca's area, the left premotor cortex, the cortex along the left intraparietal sulcus and the right cerebellum, thus replicating the results from previous studies. By contrast, no significant memory- related activation was found in these areas when silent articulatory suppression prevented the subjects from rehearsal. Instead, this non-articulatory maintenance of phonological information was associated with enhanced activity in several other, particularly anterior prefrontal and inferior parietal, brain areas. These results suggest that phonological storage may be a function of a complex prefronto-parietal network, and not localized in only one, parietal brain region. Further possible implications for the functional organization of human working memory are discussed.

Adult↗
PubMed1997

The neural correlates of the noradrenergic modulation of human attention, arousal and learning.

The prefrontal cortex has been suggested as a site of action for the noradrenergic modulation of cognition. In healthy volunteers attentional deficits can be induced by the alpha 2 adrenoceptor agonist clonidine, without impairment of more explicit tests of frontal lobe function. It is therefore possible that the effects of noradrenaline cannot be localized to a specific brain area such as the prefrontal cortex, but instead involve structures in a more widespread attentional network. A 1.5 micrograms/kg dose of clonidine or placebo was administered to 13 healthy male volunteers performing the rapid visual information processing task, which places demands on both sustained attention and working memory. Twelve positron emission tomography measurements of regional cerebral blood flow (rCBF) were collected during performance of this task and also during a rest state. A second experiment in 12 healthy volunteers examined the effects of a 1.3 micrograms/kg dose of clonidine on the rCBF changes associated with performance of a paired associates learning task compared with passive listening to word pairs. Comparison of each of the experimental tasks with its respective control replicated previous findings. A significant drug x task interaction, common to the two studies, was found in the right thalamus. Inspection of the adjusted rCBF values showed that the effect was due to attenuation of thalamic rCBF during the control states rather than to any effects of clonidine during performance of the cognitive tasks, although the effect was stronger in the rapid visual information processing study than in the paired associates learning study. The significant effect of clonidine during the control as opposed to the "cognitive' activation state is consistent with previous findings in animals and humans demonstrating greater effects of clonidine during states of relatively low arousal. The results suggest neuroanatomical dissociation of the noradrenergic modulation of arousal (via the thalamus) and attention.

Adrenergic Fibers↗
PubMed2001

A hybrid learning network for shift-invariant recognition.

A neural network and the associated learning algorithm are presented as a generic approach for invariant recognition of visual patterns independent of their geometric attributes, such as spatial location, orientation and scale. The network is a multi-layer hierarchy with each layer composed of a set of groups of nodes. The groups of the input layer represent local areas spatially arranged in the visual field according to the geometric variations. Each node in the subsequent higher layers receives input laterally from other groups of the same layer as well as vertically from the layer below. The learning that takes place in the vertical feed forward paths between layers is based on an unsupervised hybrid algorithm combining both competitive learning and Hebbian learning. As the result of the architecture and the hybrid learning, the desired invariant recognition emerges at the output layer of the network. The network can serve as a simple and biologically plausible computational model to account for the invariant object recognition in the biological visual system. Also, as the algorithm is generic and robust, it can be applied to solve various practical recognition problems.

Algorithms↗
PubMed2004

Spike synchronization in the cortex/basal-ganglia networks of Parkinsonian primates reflects global dynamics of the local field potentials.

Cortical local field potentials (LFPs) reflect synaptic potentials and accordingly correlate with neuronal discharge. Because LFPs are coherent across substantial cortical areas, we hypothesized that cortical spike correlations could be predicted from them. Because LFPs recorded in the basal ganglia (BG) are also correlated with neuronal discharge and are clinically accessible in Parkinson's disease patients, we were interested in testing this hypothesis in the BG, as well. We recorded LFPs and unit discharge from multiple electrodes, which were placed in primary motor cortex or in the basal ganglia (striatum and pallidum) of two monkeys before and after rendering them parkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. We used the method of partial spectra to construct LFP predictors of the spike cross-correlation functions (CCFs). The predicted CCF is an estimate of the correlation between two neurons under the assumption that their association is explained solely by the association of each with the LFP recorded on a third electrode. In the normal condition, the predictors account for cortical rate covariations but not for the association among the tonically active neurons of the striatum. In the parkinsonian condition, with the appearance of 10 Hz oscillations throughout the cortex-basal ganglia networks, the LFP predictors account remarkably better for the CCFs in both the cortex and the basal ganglia. We propose that, in the parkinsonian condition, the cortex-basal ganglia networks are more tightly related to global modes of brain dynamics that are echoed in the LFP.

Action Potentials↗
PubMed2003

Abnormalities of auditory P300 cortical current density in patients with schizophrenia using high density recording.

While P300 current density analysis has been performed in schizophrenic patients, the event-related potential data have never been obtained using a high density recording, nor have their cortical images been well demonstrated. In this study, the auditory P300 elicited by an oddball paradigm was recorded using a high density recording system of 128 channels. Thirteen male patients who met DSM-IV criteria for schizophrenia were compared with 20 healthy male controls. The cortical current density analysis of low resolution electromagnetic tomography (LORETA) was applied to the P300 component, and this resulted in the values of 6222 current density points over the surface of a cortex model. The inter-group difference of P300 current density was assessed using a point-by-point comparison by t-test. While the normal controls demonstrated the cortical activation of bilateral frontal, temporal and parietal cortex during the oddball paradigm, visual inspection suggested that in the schizophrenic patients these areas were less activated. The inter-group significance of P300 current density was dominant over the left hemisphere, and particularly over the left prefrontal area. It is concluded that the LORETA current density analysis localizes the neural activity from the cortical fronto-temporo-parietal network as the neural substrates of the scalp recorded P300. The dysfunction of such a network, especially over the left hemisphere, possibly subserves the scalp recorded P300 abnormality in schizophrenia.

Acoustic Stimulation↗
PubMed1989

Physician bonding: one hospital's experience.

In year one, hospital management has concluded that the objective of establishing a cost-effective physician bonding program has been realized. Early indications suggest that fundamental demand for services have increased. Additional data are being accumulated to assess the impact of the program on shifting referral patterns. Phase II expansion will continue in year two by continued recruitment efforts to include physicians, clinics and hospitals in an expanded geographic area of interest to the hospital. A Phase III community healthcare network is under consideration with proposals to the other two local hospitals. Two additional hospitals in the state are establishing compatible networks with the invitation to join the public utility in the future. As a reaction to environmental changes and increasing competition, hospitals are exploring several options to strategically position and strengthen their institutions. One of these options, the hospital-physician information network, appears to have an impact on bonding with physicians and thereby helping a hospital to maintain or increase market share. However, hospitals soon realize that the presence of a communications network alone does not achieve expected results -- stronger bonding and a positive effect on utilization. To be effective, a more comprehensive program is needed to help referral sources with their pressing needs and concerns. Based upon the findings at Saint Elizabeth Community Health Center, the impact on market share can be dramatic when the needs of the medical staff and primary-care referral sources are addressed in the design and implementation of the hospital-physician bonding program.

Computer Communication Networks↗
PubMed2004

Can von Willebrand factor, platelet-endothelial cell adhesion molecule-1 and thrombomodulin be used as alternative markers of endothelial cell injury in human glomerulonephritis?

PURPOSE: There is growing evidence that endothelial cells (EC) are active participants of an inflammatory process in glomeruli. MATERIAL AND METHODS: We compared the glomerular expression of three EC-coupled molecules, i.e. platelet-endothelial cell adhesion molecule-1 (PECAM-1 or CD31), von Willebrand factor (vWF) and thrombomodulin (TM) in 60 patients with glomerulonephritis (GN) and five normal kidneys (NK). The alkaline phosphatase anti-alkaline phosphatase method was used to examine the expression of these proteins in the biopsy specimens. RESULTS: In NK, the expression of CD31 and vWF comprised the whole glomerular network. In contrast, the expression of TM was much lower and localized mainly to EC at the vascular pole and adjacent areas. In GN, the glomerular staining for CD31 and vWF was significantly reduced. A fall in the expression of both these EC antigens was more pronounced in proliferative forms of GN (PGN) than in non-proliferative GN (NPGN) (CD31: NPGN vs. PGN, p < 0.02; vWF: NPGN vs. PGN, p < 0.05). In addition, a linear relationship between the expression of CD31 and vWF was found in GN (r = 0.8, p < 0.001). Conversely to CD31 and vWF, a marked increase in glomerular reactivity for TM was observed in all the patients with GN (GN: 2.12 +/- 0.32, NK: 0.95 +/- 0.05, p < 0.02). However, the highest expression of TM was found in membranoproliferative GN and lupus GN. CONCLUSIONS: Our results suggest that CD31 and vWF may be used as markers of glomerular EC loss during GN, whereas TM staining seems to reflect EC activation in response to circulating and/or released in situ procoagulant factors.

Adolescent↗
PubMed1996

[Neuro-cognitive models of spelling and Alzheimer disease: mutual clarification].

The neuro-cognitive models developed over the last twenty years have considerably added to the understanding of disorders of spelling and writing resulting from brain lesions. These models differentiate between central processes, damage to which explains linguistic disorders, and peripheral processes, damage to which results in praxia and related disorders. This article analyses studies which have applied these distinctions to disorders observed in Alzheimer's disease. This disease causes unusual pathological situations which show certain types of agraphia rarely seen in the relevant literature, particularly certain peripheral forms. Several studies considered demonstrate the frequency of lexical agraphia in Alzheimer's disease. These lexical disorders of written expression seem to be independent of the lexico-semantic disorders found in other areas of the intellectual processes, Central writing disorders-lexical but also phonological-would appear to be the result of relatively focussed dysfunctionings, the left gyrus angularis and left gyrus supramarginalis respectively, as is suggested in brain metabolism studies. Moreover, certain patients develop peripheral writing disorders which are at present less well known, on a cognitive and neurobiological point of view. Inferences from other pathological contexts reveals that these disorders are often associated with diffuse cerebral lesions. Therefore disorders of written expression in Alzheimer's disease may be the result of two different pathological mechanisms: central disorders arising from localized areas of dysfunctioning at the left temporo-parietal intersection; peripheral disorders linked to the dysfunctioning of a much wider network involving the parietal and frontal regions of both cerebral hemispheres. To account for the diversity of clinical pictures, we suggest a physiopathological hypothesis which could also be used as a therapeutic model in Alzheimer's disease.

Agraphia↗