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PubMed1991

Analysis of an experimental cortical network: I). Architectonics of visual areas 17 and 18 after neonatal injections of ibotenic acid; similarities with human microgyria.

Lesions of cortical areas 17 and 18 have been produced in newborn kittens by local injections of the excitotoxin ibotenic acid (ibo). Twenty-four hours after an injection on postnatal days 2 or 3, the gray matter of areas 17 and 18 near the center of the injection appears completely destroyed, with the exception of a one-to-two cell-thick layer at the bottom of layer I. Intact migrating neurons and radial glia can be found light- and electron-microscopically in the region affected. During the following weeks a several hundred micron thick cortex reforms. In the adult, this cortex consists of superficial layers I, II and III as proven by cytoarchitectonics, continuity with the corresponding layers of the normal cortex and cellular composition. We believe that the recovery is due to completion of migration by neurons spared by the ibo injection. More severe destruction of cerebral cortex, i.e. complete loss of the neuronal layers or their reduction to a few cell-thick mantles can be obtained with ibo injections at the end of the second or, respectively, first postnatal week. Severity of lesion also depends on the dose of ibo injected. There are interesting similarities between the ibo-injured cortex and two human neocortical displasias: microgyria and ulegyria.

Aging↗
PubMed1994

Corneal keratocytes: in situ and in vitro organization of cytoskeletal contractile proteins.

PURPOSE: Recent studies of corneal wound healing suggest that activated corneal keratocytes develop myofibroblast-like characteristics including a putative contractile apparatus comprised, in part, of intracellular microfilament bundles (i.e., stress fibers) containing f-actin, myosin, and alpha-actinin; extracellular fibronectin fibrils; and fibronectin surface membrane receptors (alpha 5 beta 1 integrin). The purpose of this study was to determine the expression and organization of specific components of the contractile apparatus in normal, quiescent (in situ) corneal keratocytes, and to compare the in situ organization with that of activated, tissue culture (in vitro) corneal keratocytes that potentially mimic wound healing fibroblasts. METHODS: Cat corneal tissue was obtained immediately after sacrifice and was either fixed for in situ studies or cultured with MEM supplemented with 10% fetal calf serum for in vitro studies. Keratocytes (in situ and in vitro) were stained with the following probes: phalloidin, a mushroom toxin that specifically binds to f-actin; rabbit anti-bovine aortic myosin; monoclonal anti-human alpha-actinin; monoclonal anti-human vimentin; rabbit anti-human alpha 5 beta 1 integrin; monoclonal anti-human alpha 5 integrin; monoclonal anti-human connexin 43; and goat anti-human fibronectin. The cytoskeletal organization and co-localization were evaluated using epifluorescent and confocal microscopy. RESULTS: Normal, quiescent corneal keratocytes were distributed within the cornea as a lattice network, interconnected by broad, cellular processes extending from a flattened cell body. The f-actin distribution of in situ keratocytes was predominantly cortical and appeared to be closely associated with the plasma membrane. In addition, punctate areas that appeared to correlate with the localization of adhesion sites were identified. These punctate regions appeared to stain with antibodies to alpha 5 beta 1 but to not alpha 5. These data suggest that the fibronectin receptor, alpha 5 beta 1 integrin, is not present on normal corneal keratocytes. Based on co-localization studies, rabbit anti-bovine aortic myosin and monoclonal anti-alpha-actinin staining had similar distributions to FITC-phalloidin. Interconnections between keratocytes also showed staining for connexin 43, indicating the presence of gap junctions. By contrast, activated, cultured (in vitro) keratocytes showed an FITC-phalloidin staining pattern localized predominantly along intracellular stress fibers not detected in normal, quiescent keratocytes. Myosin and alpha-actinin staining had a similar stress fiber distribution, arranged in alternating bands and suggesting a sarcomeric distribution. Associated with stress fibers there was both anti-alpha 5 beta 1 and anti-alpha 5 staining, indicating the presence of focal adhesions. CONCLUSIONS: This study demonstrates that there are major structural differences in the organization of contractile cytoskeletal proteins between normal, quiescent (in situ), and activated (in vitro) keratocytes. In situ, contractile proteins appear to be associated with the cortical f-actin network, probably related to maintenance of cell shape and interconnectivity. Alternatively, activated keratocytes were characterized by the presence of a putative contractile apparatus comprised of f-actin, myosin, and alpha-actinin organized into sarcomeric, muscle-like bundles (stress fibers) associated with focal contacts containing alpha 5 beta 1 integrin. These data suggest that activation of keratocytes, i.e. myofibroblast transformation, must involve the reorganization of cytoplasmic contractile proteins as well as the expression of alpha 5 beta 1 integrin and the formation of focal contacts.

Animals↗
PubMed1983

A cognitive-motor network demonstrated by positron emission tomography.

The rate of local cerebral glucose metabolism was measured in subjects receiving a verbal (n = 4) and a spatial (n = 4) task. The verbal task produced greater metabolism in Wernicke's area relative to the right hemispheric homotopic region, whereas the spatial task produced greater metabolic activity in the right hemispheric homotopic region. Broca's area and its right hemisphere counterpart showed symmetrical activity during the verbal task, but there was a significant asymmetry to the right during the spatial task. Lateralized task effects were also obtained in the frontal eye fields, supporting a hypothesized neural network linking cognitive activity with motor orientation.

Adult↗
PubMed2006

Localizing complex neural circuits with MEG data.

During cognitive processing, the various cortical areas, with specialized functions, supply for different tasks. In most cases then, the information flows are processed in a parallel way by brain networks which work together integrating the single performances for a common goal. Such a step is generally performed at higher processing levels in the associative areas. The frequency range at which neuronal pools oscillate is generally wider than the one which is detectable by bold changes in fMRI studies. A high time resolution technique like magnetoencephalography or electroencephalography is therefore required as well as new data processing algorithms for detecting different coherent brain areas cooperating for one cognitive task. Our experiments show that no algorithm for the inverse problem solution is immune from bias. We propose therefore, as a possible solution, our software LOCANTO (LOcalization and Coherence ANalysis TOol). This new package features a set of tools for the detection of coherent areas. For such a task, as a default, it employs the algorithm with best performances for the neural landscape to be detected. If the neural landscape under attention involves more than two interacting areas the SLoreta algorithm is used. Our study shows in fact that SLoreta performance is not biased when the correlation among multiple sources is high. On the other hand, the Beamforming algorithm is more precise than SLoreta at localizing single or double sources but it gets a relevant localization bias when the sources are more than three and are highly correlated.

Bias↗
PubMed2005

The FARMING approach: main results and perspectives of the French FARMING groups.

The Chernobyl accident led to a long-term crisis that affected agriculture, food and living conditions in complex ways, and that modified the usual economical, political and social relations between public and private stakeholders at local, national and international level. The EC FARMING project aims to create a European stakeholder network to consider possible rehabilitation strategies for rural areas contaminated after a nuclear accident. The Institute of Patrimonial Strategies of the National Institute on Agronomy had responsibility for setting up the French stakeholder group. The objective was to develop favourable conditions and ways whereby stakeholders could deal with such a complex situation as a nuclear emergency and develop rehabilitation strategies. The results from the 3-year work programme on both strategic and technical aspects, showed an increasing commitment from the stakeholders that led to the building up of a common understanding of what a nuclear accident could be and how it could be dealt with.

Agriculture↗
PubMed2002

SDS-resistant active and thermostable dimers are obtained from the dissociation of homotetrameric beta-glycosidase from hyperthermophilic Sulfolobus solfataricus in SDS. Stabilizing role of the A-C intermonomeric interface.

beta-Glycosidases are fundamental, widely conserved enzymes. Those from hyperthermophiles exhibit unusual stabilities toward various perturbants. Previous work with homotetrameric beta-glycosidase from hyperthermophilic Sulfolobus solfataricus (M(r) 226,760) has shown that addition of 0.05-0.1% SDS was associated with minimal secondary structure perturbations and increased activity. This work addresses the effects of SDS on beta-glycosidase quaternary structure. In 0.1-1% SDS, the enzyme was dimeric, as determined by Ferguson analysis of transverse-gradient polyacrylamide gels. The catalytic activity of the beta-glycosidase dimer in SDS was determined by in-gel assay. A minor decrease of thermal stability in SDS was observed after exposure to temperatures up to 80 degrees C for 1 h. An analysis of beta-glycosidase crystal structure showed different changes in solvent-accessible surface area on going from the tetramer to the two possible dimers (A-C and A-D). Energy minimization and molecular dynamics calculations showed that the A-C dimer, exhibiting the lowest exposed surface area, was more stabilized by a network of polar interactions. The charge distribution around the A-C interface was characterized by a local short range anisotropy, resulting in an unfavorable interaction with SDS. This paper provides a detailed description of an SDS-resistant inter-monomeric interface, which may help understand similar interfaces involved in important biological processes.

Binding Sites↗
PubMed1990

Designing a continuing medical education programme in Malaysia based on practitioners' needs.

A cross-sectional national survey was conducted amongst a random sample of medical practitioners registered in 1988 with the Malaysian Medical Council with the purpose of determining their educational needs with regards to continuing medical education (CME). A 91.0% response rate was obtained. It was found that more than 70% wanted a programme that would provide them with new practical skills and new knowledge or advances in specific fields. About 2/3 also wanted their intellectual skills in problem-solving to be further developed. Reinforcement of communication skills appears to be of secondary importance. They would also like a programme of CME to help them monitor and improve their diagnostic accuracy, investigative habits, prescribing pattern, skills in interpreting diagnostic tests and management of common illnesses. As for content areas it was found that the problems they have least confidence in managing come mainly from the disciplines of psychiatry, obstetrics and gynaecology, and emergency and critical care. More than 90% preferred self-learning methods with some group-type activities. Based on these needs it was recommended that a programme of CME be developed with orientation towards a practice-based setting, self-directed learning, utilizing problem-solving approaches and focusing on the major content areas identified. In addition, activities such as small-group discussions, clinical rounds and journal clubs should be encouraged to develop into local network group activities to supplement the self-learning and present lectures and talks.

Clinical Competence↗
PubMed2005

Estimation and allocation of solid waste to bin through geographical information systems.

This study presents a geographical information system (GIS)-based procedure for the precise estimation of solid waste generation, computed using the local population density and income group distribution. Using a triangulated irregular network (TIN) in a GIS environment, the procedure further determines the command area for waste allocation to a particular bin which is generally located so the route slopes towards the collection points for ease of transportation by cart pullers. Computational results of bin location, type, size and the frequency of removal are presented for a typical urban area with known population density, income group distribution, road network and topology.

Cities↗
PubMed1997

Fascin, a sensitive new marker for Reed-Sternberg cells of hodgkin's disease. Evidence for a dendritic or B cell derivation?

Immunohistochemical localization of human fascin, a distinct 55-kd actin-bundling protein, was determined for a wide variety of lymphoid tissues (364 specimens total). In non-neoplastic tissues, reactivity was highly selective and localized predominantly in dendritic cells. In the thymus, this protein was distinctly localized to medullary dendritic cells. In reactive nodes, interdigitating reticulum cells of T zones, cells in subcapsular areas, and cells of the reticular network were reactive, with variable reactivity observed for follicular dendritic cells. Splenic dendritic cells of the white pulp and sinus-lining cells of the red pulp were reactive. Endothelial cells of all tissues exhibited variable reactivity. Lymphoid cells, myeloid cells, and plasma cells were uniformly nonreactive. In the peripheral blood, only dendritic (veiled) cells were reactive for fascin. A striking finding was observed for cases of Hodgkin's disease (total 187 cases). In all cases of nodular sclerosis (132), mixed cellularity (34), lymphocyte depletion (2), and unclassified types (5), all or nearly all Reed-Sternberg cells and variants were immunoreactive for fascin. Neoplastic cells exhibited strong diffuse cytoplasmic staining and frequently assumed dendritic shapes, particularly in the nodular sclerosis type, producing an interdigitating meshwork or syncytial network of cells. In cases of mixed cellularity type, neoplastic cells generally appeared more discrete. In all 14 cases of nodular lymphocyte predominance type, L&H variants were nonreactive. By contrast, neoplastic lymphoid cells of only 24 of 156 (15%) other lymphoid neoplasms (127 B cell, 27 T cell, and two null cell evaluated) were reactive for fascin. Fascin represents a highly effective marker for detection of certain dendritic cells in normal and neoplastic tissues, is an extremely consistent marker for Reed-Sternberg cells and variants of Hodgkin's disease (except L&H types), and may be helpful to distinguish between Hodgkin's disease and non-Hodgkin's lymphoma in difficult cases. The staining profile for fascin raises the possibility of a dendritic cell derivation, particularly an interdigitating reticulum cell, for the neoplastic cells of Hodgkin's disease, notably in nodular sclerosis type. However, as fascin expression may be induced by Epstein-Barr virus infection of B cells, the possibility that viral induction of fascin in lymphoid or other cell types must also be considered in Epstein-Barr virus-positive cases.

B-Lymphocytes↗
PubMed2003

[The French Airborne Pollen Network: current situation and prospects for improvement].

The french network of aeropalynology includes traps very close together and vast areas without any trap as well. A study was launched in order to optimise this network, without the number of traps increasing too much. Five criteria are successively reviewed to rationalise the spatial cover. Equi-distance of sites has to be balanced by the number of concerned people. But the need for having long time series is incentive to delete only as a last resort the traps which are reliable for a long time. Moreover, apart from the general network, some local or regional features make indispensable a trap in such-and-such a place (health resort), or justify a higher density of traps in such-and-such an area (the Rhône-Alpes concerning ragweed, the Mediterranean South concerning cypress).

Air↗
PubMed2001

Epileptogenic networks: cerebral dysplasias and cerebral ectopias.

There are three areas in which functional imaging may be applied to malformations of cortical development (MCD) that give rise to epilepsy: the localization of epileptic activity; the identification of areas of functional abnormality; the mapping of normal cerebral functions, and how these may be displaced. Single photon emission computerized tomography (SPECT) commonly shows interictal hypoperfusion and ictal hyperperfusion. Positron emission tomography (PET), using (18)F-fluorodeoxyglucose, often shows glucose metabolism in ectopic grey matter and hypometabolism in MCD, compared with normal cortex. Cognitive activation tasks, using PET or fMRI, have shown that malformed cortex may participate in cerebral functions, but also widespread atypical cortical organization. Cognitive activation tasks using fMRI are useful when planning surgical resections close to eloquent cortex. Binding of (11)C-flumazenil to central benzodiazepine receptors (cBZR) is often abnormal in MCD, and in areas of cortex that appear normal on MRI, with increased and decreased binding. MR Spectroscopy also reveals abnormalities that are more extensive than the MRI visible lesion, implying more widespread structural and functional abnormalities. The recording of EEG during fMRI has allowed the latter to be used to localize cerebral areas involved in the generation of interictal epileptiform activity. Electroencephalograph source localization and magneto-encephalography may also prove to be useful in the localization of interictal epileptiform activity, particularly when fMRI data are used to constrain the solutions.

Cerebral Cortex↗
PubMed2004

[Communal health promotion in child and adolescent health services -- report on the experience with a organisational model for setting up an interdisciplinary network in a socially important area].

This report focusses on health promotion for children adolescents und families and on the aspects of organisation and resources. In 1991 the Public Youth Health Care (KJGD), a community health service for children und adolescents, set up a multi-professional "district committee" of distributors in leading positions in a socially important area (social workers, school teachers, kindergarten teachers, councillors, medical personnel, architects and town planners etc.). Medical examinations of all school beginners and children with special educational needs formed the basis of the social paediatric observations and data. Until 2003 the author was responsible for the management and coordination of this local interdisciplinary district committee of leading representatives from local social and educational organisations as well as town councillors who created a local multi-professional network. The district health reports of the discussions in the district committee including the different professional aspects of health promotion were passed on to the local politician actively involved in the discussions with specialists and invested in social and health promotion projects. Social paediatric issues and preventative strategies became part of the work in social and educational organisations in the area und the city. A healthy environment for children und families was promoted. For the KJGD the conceptual work with distributors in leading positions led to initiatives for communal health promotion making time-saving use of existing resources.

Adolescent↗
PubMed1977

The end-stage renal disease networks: an attempt through Federal regulation to regionalize health care delivery.

Recognizing the needs of patients with end-stage renal disease (ESRD), the federal government passed legislation in 1972, establishing Medicare coverage for 92 per cent of the diseased victims regardless of age. However, federal health planners did not in many areas, take into account what was already being accomplished on the state and local level. As a result, the implementation of the provision has created complications of its own. This case study of New Jersey illustrates that until existent informal health delivery networks are incorporated into federal health planning, the taxpayer and health care consumer will not get the most mileage for his or her dollar.

Certificate of Need↗
PubMed2001

Self-organized critical drainage networks.

We introduce time-dependent boundary conditions in a model of drainage network evolution based on local erosion rules. The changing boundary conditions prevent the model from becoming stationary; it approaches a state where fluctuations of all sizes occur. The fluctuations in the sizes of the drainage areas show power law behavior with an exponent that differs significantly from that of the static distribution of the drainage areas. Thus, the model exhibits self-organized criticality and proposes a novel concept for predicting fractal properties of drainage networks.

Journal Article↗
PubMed2004

Distribution of the neuropeptide FF1 receptor (hFF1) in the human hypothalamus and surrounding basal forebrain structures: immunohistochemical study.

Neuropeptides with C-terminal RFamide and their receptors NPFF1 (FF1) and NPFF2 (FF2) have been implicated in a wide variety of functions, including nociception and autonomic and neuroendocrine regulation. Recent studies indicate that the FF1, but not FF2, mRNA is highly expressed in the human hypothalamus. In the present study, localization of FF1 in the human hypothalamus and surrounding regions was studied immunohistochemically by using an antibody against human FF1 (hFF1). Brain sections from healthy 30-50-year-old individuals were used for hFF1 immunohistochemistry. The highest density of hFF1-stained cells was found in the posterior division of the bed nucleus of the stria terminalis and in the zona incerta. A moderate density of cells was observed in the perifornical nucleus, infundibular nucleus, tuberomammillary nucleus, and lateral tuberal nucleus. A lesser density was revealed in the dorsomedial hypothalamic nucleus, basal nucleus of Meynert, and anterior amygdaloid area. Only scattered hFF1 cells were found in the suprachiasmatic nucleus and hypothalamic paraventricular nucleus. hFF1 cells and fibers were absent in the supraoptic and mammillary nuclei. Single and double strands of hFF1-immunopositive punctate varicosities marked cellular processes of different caliber. The density of hFF1-immunostained fiber networks did not always coincide with that of hFF1-immunostained cells. hFF1 immunoreactivity was also found in the wall of blood vessels within most brain areas studied. Localization of hFF1 in discrete regions of the hypothalamus and extended amygdala may provide important insights into the role of amidated neuropeptides in central autonomic and neuroendocrine control in the human brain.

Adult↗
PubMed2000

[Spreading of porcine kidney epithelial cells under normal conditions and under the effect of inhibitors of energy metabolism. II. Behavior of cellular organelles].

In the present work the behavior of mitochondria and lysosomes during cell spreading has been investigated in normal conditions and under ATP-synthesis inhibitors: sodium aside and N,N-dicyclohexylcarbodiimide (DCCD). In the control culture, microtubules run along the stable edge and perpendicular to the leading edge in most of spreading cells. As a whole, microtubules form a dense network in these cells. However, the radial cells contain bundles of microtubules, radiating from the perinuclear area or form circular arrays around the nucleus. The microtubule network is more dense under inhibitory treatment, than in control conditions. In the control culture the spherical cells display numerous small mitochondria (staining with Rhodamine 123). In the process of cell spreading some elongated mitochondria appear, most of them being localized in the perinuclear area. The mitochondria of cells with radial microtubule organization are directed towards the cell periphery, while in cells with circular bundles of microtubules the mitochondria are localized chaotically. Under DCCD treatment the mitochondria retain the staining for 2-3 h. In the spreading cells, round mitochondria may be distributed all over the cytoplasm. In the presence of sodium aside the mitochondria are not stained. However, by means of phase contrast microscopy some disoriented thread-shaped structures are observed, obviously corresponding to mitochondria. In the control conditions, lysosomes (stained with Acridine orange) in spreading cells are dispersed chaotically, all over the cytoplasm, or are localized in the perinuclear area. In the presence of sodium aside lysosomes are observed only in the perinuclear area. Under DCCD treatment lysosomes do not accumulate the dye. Thus, the cytoskeleton modification and changes in the properties of membrane organelles, induced by ATP-synthesis inhibitors, do not prevent attachment, spreading or cell polarization.

Adenosine Triphosphate↗
PubMed2003

Design and training of a neural network for predicting the solvent accessibility of proteins.

A feed-forward neural network has been developed to predict the solvent accessibility/accessible surface area (ASA) of proteins using improved design and training methods. Several network issues ranging from the coding of ASA states to the problem of local minima of learning curve, have been addressed. Successful new approaches to overcome these problems are presented. Set of trained network weights for each ASA threshold is provided. It has been established that the prediction accuracy results with neural network are better than other reported results of ASA prediction, despite a high test to training data ratio.

Amino Acids↗
PubMed1996

The Yoruba farm market as a communication channel in guinea worm disease surveillance.

Disease eradication programmes are by definition time bound and require strategies that facilitate timely intervention. Surveillance, which undergirds eradication, also requires timely strategies. Finding such strategies is especially challenging when the target disease is endemic in remote areas, e.g. guinea worm disease, the focus of this study. A strategy of market based surveillance was pilot tested in Ifeloju Local Government Area (LGA) of Oyo State, Nigeria. The project goal was to design a surveillance system that both fit into the natural communication network of rural people, and also enlisted their active involvement. Ethnographic research methods were employed to learn about market location, structure, catchment area and attendance pattern. Four larger farm markets (serving 164 hamlets with 17,000 population) were chosen. Each hamlet was visited and a volunteer 'reporter' was recruited. Reporters were trained on case recognition and detection, first aid and prevention, with a sensitivity to distinguishing indigenous and clinical perceptions of guinea worm. The market cycle was based on the traditional four-day week. Field workers visited every second market 16 times between October 1990 and February 1991. The reporter was expected to identify correctly the first case of the season and thus label the village as endemic for the season. Reporters gave oral reports, and positive indications were followed up within 48 hr by field workers, who verified the case and administered first aid. All hamlets were visited once a month to verify negative reports. Reporter attendance was monitored. Those who had a formal role in the market, e.g. sales agents, had better attendance than ordinary farmers who came only to sell their own produce. Knowledge of market structure and attender roles offers a guide for adapting this surveillance approach to other cultural systems and health issues.

Adolescent↗