Adsorption of Organic Dyes on Magnetic Iron Oxide Nanoparticles. Part I: Mechanisms and Adsorption-Induced Nanoparticle Agglomeration.

This series of two papers is devoted to the effect of organic dye (methylene blue, MB; or methyl orange, MO) adsorption on the surface of either bare or citrate-coated magnetic iron oxide nanoparticles (IONPs) on their primary agglomeration (in the absence of an applied magnetic field) and secondary field-induced agglomeration. The present paper (Part I) is focused on physicochemical mechanisms of dye adsorption and adsorption-induced primary agglomeration of IONPs. Dye adsorption to oppositely charged IONPs is found to be mostly promoted by electrostatic interactions and is very sensitive to pH and ionic strength variations. The shape of adsorption isotherms is correctly reproduced by the Langmuir law. For the particular MB/citrated IONP pair, the maximum surface density of adsorbed MB seems to correspond to the packing density of an adsorbed monolayer rather than to the surface density of the available adsorption sites. MB is shown to form H-aggregates on the surface of citrate-coated IONPs. The effective electric charge on the IONP surface remains nearly constant in a broad range of surface coverages by MB due to the combined action of counterion exchange and counterion condensation. Primary agglomeration of IONPs (revealed by an exponential increase of hydrodynamic size with surface coverage by MB) probably comes from correlation attractions or π-stacking aromatic interactions between adsorbed MB molecules or H-aggregates. From the application perspective, the maximum adsorption capacity is 139 ± 4 mg/g for the MB/citrated IONP pair (pH = 4-11) and 257 ± 16 mg/g for the MO/bare IONP pair (pH ∼ 4). Citrated IONPs have shown a good potential for their reusability in water treatment, with the adsorption efficiency remaining about 99% after nine adsorption/desorption cycles.

Integration of fiber Bragg grating temperature sensors in plasma facing components of the WEST tokamak.

Plasma Facing Components (PFC) temperature measurement is mandatory to ensure safe high power and long pulse tokamak operation. IR thermography systems which are widely used in magnetic fusions devices become challenged with the choice of tungsten as a PFC material in the ITER tokamak, mainly due to emissivity uncertainties and reflection issues in a hot environment. Embedded temperature measurements are foreseen to cross-check the IR thermography measurements. Fiber Bragg grating sensors are potentially of great interest for this application because they are immune to electromagnetic interference and allow the measurement of a large number of temperature spots on a single fiber. Four optical fiber temperature sensing probes, each of them including 11 regenerated fiber Bragg gratings equally spaced by 12.5 mm (equivalent to one ITER-like tungsten monoblock), have been specifically designed and manufactured for the WEST project (W-tungsten Environment and Steady State Tokamak). The four probes are embedded in W-coated graphite components at two different distances from the surface, 3.5 mm and 7 mm, to cover a wide range of temperatures up to 900 °C. This paper addresses the design and integration issues and the qualification and performance assessment performed in the laboratory. It also shows the first measurements of this new diagnostic achieved in a tokamak environment during baking of the machine and during early diverted plasma exposure.

Short increase of BDNF messenger RNA triggers kainic acid-induced neuronal hypertrophy in adult mice.

Neurotrophin gene expression in adult brain varies according to physiological activity and following brain injury, suggesting a role in neuronal maintenance and plasticity. However, the exact roles and mechanisms of action of neurotrophins in the adult brain are still poorly understood. We have recently demonstrated that neurons of the adult mouse dentate gyrus can develop a conspicuous morphogenetic response to intrahippocampal injection of kainic acid. This response is correlated with long-lasting overexpression of the brain-derived neurotrophic factor gene, suggesting a causal relationship between molecular and structural changes. To test this hypothesis, brain-derived neurotrophic factor messenger RNA were sequestered in vivo by administration of antisense oligodeoxynucleotides. When administered before 20 h post-kainate, antisense oligodeoxynucleotides totally prevented the kainate-induced neuronal hypertrophy, while sense or missense sequences had no effect. On the other hand, the hypertrophic response was observed when antisense administration was begun 24 h post-kainate, indicating an involvement of brain-derived neurotrophic factor messenger RNA in the initiation of structural changes, but not in their evolution. The hypertrophy was blocked by inhibition of tyrosine kinase activities by K252a, suggesting an involvement of Trk high affinity receptors. Administration of human recombinant brain-derived neurotrophic factor without previous treatment by kainate failed to induce any morphogenetic response. These results show that a short activation of the brain-derived neurotrophic factor gene can, in association with neuronal activation by kainate, trigger dramatic and long-lasting morphological changes in adult neurons. A physiological role of brain-derived neurotrophic factor in adult brain could therefore be to link, by autocrine/paracrine action, activation of glutamate receptors and neuronal morphological adaptive responses.

Morphogenetic effect of kainate on adult hippocampal neurons associated with a prolonged expression of brain-derived neurotrophic factor.

Intraperitoneal or intrahippocampal injections of kainate induce both hippocampal cell death and axonal remodeling of the dentate gyrus granular neurons. We report here that injection of kainate into the dorsal hippocampus of adult mice may also trigger a conspicuous and long-lasting global trophic response of granule cells. Morphological changes include somatic and dendritic growth and increased nuclear volume with ultrastructural features characteristic of neuronal development. The trophic response is correlated with a specific overexpression of brain-derived neurotrophic factor that is maintained for at least six months. This shows that plasticity in adult neurons can, in addition to axonal remodeling, extend to generalized cell growth. Our results further suggest that brain-derived neurotrophic factor could be involved in the activation and/or maintenance of this phenomenon.

Decreased pentylenetetrazol-induced expression of zif/268 in NGF-transgenic mice.

Expression of the proto-oncogene zif/268 was investigated by in situ hybridization in the hippocampus and cerebral cortex of nerve growth factor (NGF)-transgenic mice during pentylenetetrazol (PTZ)-induced seizures. NGF-transgenic mice displayed normal basal levels of zif/268 mRNA in cortex and hippocampal formation except for the dentate gyrus which contained significantly reduced levels. PTZ induced a similar transient increase of zif/268 mRNA in cortex and Ammon's horn of normal and NGF-transgenic mice. On the other hand, increase of zif/268 mRNA in the dentate gyrus was significantly lower in transgenic mice. Reduced PTZ-induced activation of zif268 may reflect a decreased sensitivity of NGF-transgenic animals to epilepsy by direct or indirect interaction of NGF with immediate early genes.

[Intracranial dural arteriovenous fistula with spinal venous drainage]. / Fistules artério-veineuses durales intracrâniennes à drainage veineux médullaire.

Two cases of intracranial dural arteriovenous fistulae draining into the medullary veins are reported. One patient was a 68-year old man who experienced brief and repeated episodes of paraplegia, followed by a permanent spinal cord syndrome. The other patient was a 74-year-old woman who rapidly developed a syndrome of the medulla and spinal cord. In both cases spinal cord angiography failed to show vascular malformations, but myelography revealed venous imprints and magnetic resonance imaging of the cervical spinal cord disclosed a pre-medullary signal. Cerebral angiography showed an intracranial arteriovenous fistula fed by the external carotid artery and draining into the veins of the posterior fossa and the spinal venous network. Complete occlusion of the fistula was achieved by embolization with microparticles. Intracranial dural arteriovenous fistulae draining into the medullary veins are rare: to our knowledge, only 4 cases have been reported. Such lesions must be considered whenever a spinal cord syndrome has no detectable cause.

Bioethical language and its dialects and idiolects.

In their search for answers to the relevant theoretical questions on importing knowledge in practical ethics, the authors take an instrumental approach to metaphor. This figure of language allows one to compare language and linguistic variants to bioethics and knowledge. As defined by the dictionary, an 'idiom' is the official language of a nation, a 'dialect' is a regional variant of an idiom, and an 'idiolect' is an individual variant of a dialect. The bioethical idiom is thus seen as a linguistic set constituting a 'bioethical nation'. Since it is situated above particular dialects, it exercises more than a regulatory role over the discipline. In this article, in order to focus on the process of transmission of knowledge in bioethics, the authors chose Diego Gracia's work as a paradigmatic reference to the question on the transculturation of dialects and the relations in bioethics which are considered 'peripheral' or 'central'. Although this researcher found the key question pointing to the core of the problem of importing dialects, he is still searching for a proper answer to the cultural/bioethical context/contradiction.

[Possible exploitation of a pharmacovigilance center concerning the risk of teratogenesis]. / Exploitation possible d'un centre de pharmacovigilance concernant le risque de tératogenèse.

Evaluating a teratogenic risk remains a difficult problem, since the existing data in this field is fragmentary. One can consider using the material obtained by the follow-up of pregnancies which have motivated a telephone consultation to an Information Center. The material could, within limits, be used to give some security. If the present numbers do not change, it would take around four years to obtain data concerning 150 women exposed during the first trimester of their pregnancy.

[Ethical behavior in the daily professional practice of nurses]. / O agir ético na prática profissional cotidiana das enfermeiras.

The daily practice of nurses is full of situations that demand a close analysis of the sociocultural context, so that the appropriate decisions are made. These decisions can either be of technical or ethical nature. In the present study, the authors reflect about the professional practice of nurses, focusing especially on the process of ethic decision making. They also relate these decisions to some of the ethic theoretical frameworks in order to indicate the references that guide the nurse's practices in the different professional situations.

Progress of the ITER equatorial vis/IR wide angle viewing system optical design.

The equatorial vis/IR wide angle viewing system is present in four ITER diagnostic equatorial ports. This instrument will cover a large field of view with high spatial and temporal resolutions, to provide real time temperature measurements of plasma facing components, spectral data in the visible range, information on runaway electrons, and pellet tracking. This diagnostic needs to be reliable, precise, and long lasting. Its design is driven by both the tokamak severe environment and the high performances required for machine protection. The preliminary design phase is ongoing. Paramount issues are being tackled, relative to wide spectral band optical design, material choice, and optomechanical difficulties due to the limited space available for this instrument in the ports, since many other diagnostics and services are also present. Recent progress of the diagnostic optical design and status of associated R&D are presented.

New reproductive technologies, ethics and legislation in Brazil: a delayed debate.

This paper focuses on the debate about the utilization of new reproductive technologies in Brazil, and the paths taken in the Brazilian National Congress in an attempt to draw up legislation to regulate the clinical practice of human assisted reproduction. British documents, such as the Warnock Report and Human Fertilization and Embriology [sic] Authority (HFEA) are used for thorough reference. The analysis of the Law Projects in the National Congress, the Resolution by the Federal Medicine Council, Resolution 196/96 and documents by the the Ministerio Publico (Public Prosecution Office), supplied the bases for the discussion. The principal question involved is the observation of different technical and moral prientations [sic] that influence the conduct of the issue in the legislative process. It is possible to observe that the main focus of the projects relates to the rights and interests of the children, to those possibly benefited by the technique and to embryo reduction. Very little attention has been directed to the issues of sexual and reproductive rights and to the health of the women submitted to the new reproductive techologies [sic].

Correlated axonal sprouting and dendritic spine formation during kainate-induced neuronal morphogenesis in the dentate gyrus of adult mice.

Several examples of structural plasticity in the adult brain have been provided in the hippocampus, among which the most striking concerns axonal remodeling of the dentate gyrus granule cells. We have recently demonstrated that a single injection of kainic acid into the dorsal hippocampus of adult mice triggers a conspicuous morphogenetic response of granule cells. Cellular labeling with biocytin 1, 2, and 4 weeks after injection of kainate revealed a progressive increase in dendritic thickness and length (up to 2.5-times), combined with an increase in the number of dendritic spines. This correlation resulted in the conservation of total spine density. No modifications of the dendritic arborization pattern were noted. In addition to dendritic changes, the number of axonal profiles observed within the hypertrophied granular layer and the inner part of the molecular layer appeared dramatically increased. Timm staining and anterograde labeling of two of the main extra-hippocampal afferent systems (i.e., septal, entorhinal) evidenced sprouting of mossy fibers and of septal afferents. Entorhinal fibers were not obviously modified. As revealed by calretinin-immunohistochemistry, commissural afferents also responded by an extensive sprouting. In addition, increases of dendritic spine number and dendritic length were noticeably greater in portions of dendrites that receive mossy fiber collaterals and septal and hypothalamic afferents, than in the external portion which receives entorhinal afferents. Although qualitative, this correlation suggests a relationship between kainate-induced structural plasticity of mature granule cells and the specific capacities of afferent systems to elaborate axon collaterals.