Interêt de la Refraction Sous Cycloplegie chez l’Adulte Jeybe a Citonou

Les vices de réfraction ou amétropies sont représentés par toutes les situations où le système optique de l’œil ne permet pas de focaliser l’image d’un objet sur la rétine. Cette recherche se voulait d’étudier les variations de la réfraction sous cycloplégie chez l’adulte jeune. Elle était rétrospective sur 05 ans à l’ex Hôpital d’Instruction des Armées – Centre Hospitalier Universitaire de Cotonou considérant 2224 yeux de patients âgés de 18 à 38 ans respectant les critères d’inclusion. La régression linéaire a été utilisée en vue d’étudier la relation entre la puissance des sphères, du cylindre et l’équivalent sphérique avant et après la cycloplégie. L’âge moyen des patients était de 27,2 ans ± 6,1. Les céphalées représentaient 56,1% des motifs de consultation et la douleur oculaire 51,8%. Avant la cycloplégie, on comptait 57,7% de myopes et 29,8% d’hypermétropes ; après la cycloplégie, 20,5 % de myopes et 74,1% d’hypermétropes. À partir des équivalents sphériques, la variation moyenne de la puissance des sphères était statistiquement significative (p < 0,0001). Elle était de 0,14 D chez les myopes, de 0,26 D chez les hypermétropes. La cycloplégie a une influence significative sur l’équivalent sphérique dans toutes les tranches d’âge jusqu’à 38 ans (p < 0,0001). L’estimation de la réfraction sans cycloplégie n’est donc pas précise. En effet, la cycloplégie en relâchant l’accommodation permet d’estimer de façon pertinente la valeur exacte et précise de la réfraction.   Refractive errors or ametropias encompass situations where the optical system of the eye fails to focus the image of an object onto the retina. This study aimed to investigate variations in refraction under cycloplegia in young adults. It was a retrospective study conducted over a period of 5 years at the former Military Teaching Hospital - University Hospital Center of Cotonou, involving 2224 eyes of patients aged 18 to 38 years who met the inclusion criteria. Linear regression was employed to examine the relationship between the power of spheres, cylinders, and spherical equivalent before and after cycloplegia. The average age of patients was 27.2 years ± 6.1. Headaches accounted for 56.1% of the reasons for consultation, and ocular pain for 51.8%. Before cycloplegia, 57.7% were myopic, and 29.8% were hyperopic; after cycloplegia, 20.5% were myopic, and 74.1% were hyperopic. Based on spherical equivalents, the average change in sphere power was statistically significant (p < 0.0001). It was 0.14 D for myopes and 0.26 D for hypermetropes. Cycloplegia had a significant influence on the spherical equivalent across all age groups up to 38 years (p < 0.0001). Therefore, estimating refraction without cycloplegia is not accurate. Indeed, cycloplegia, by relaxing accommodation, allows for a relevant estimation of the exact and precise value of refraction

Green mecanochemical process for carbon nanotubes coating with humic acid: application and ecotoxicity evaluation.

Nanomaterials (NM) are promising for environmental remediation due to their unreleased properties such as high surface area and reactivity. Chemical oxidations (H2SO4/HNO3) have been applied to carbon NM in order to favor their application, but these are expensive and hazardous. In this work, industrial grade multiwalled carbon nanotubes (raw-MWCNT) were coated with humic acid (HA) by a ball milling processing (solid state). The aim was to apply a green mechanochemical process to improve the colloidal stability of MWCNTs and their removal capacity of metals. The HA-MWCNT complex was studied by atomic force microscope (AFM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), dynamic light scattering (DLS), electrophoretic light scattering (ELS) and ultraviolet-visible spectroscopy (UV-Vis). Cu2+ sorption from water by HA-MWCNT, MWCNT-COOH and milledMWCNT were compared. Acute bioassays (96h) were performed with Daphnia magna exposed to 0.0; 0.1; 1.0; 5.0 and 10.0 mg/L of HA-MWCNT. Our results showed that the coating process enhanced the zeta potential of raw-MWCNT of -25.4±0.2 mV to -37.4±0.7 mV and reduced their hydrodynamic diameter of 393.2±27.3 nm to 212.5±5.6 nm in ultrapure water. AFM images of HA-MWCNT showed that it has an irregular surface, due to the humic acid coating. The complex was 4 times (84±1.8%) more efficient to remove Cu2+ than MWCNTCOOH (20.0±1.4%) and 11 times compared to milled-MWCNT (7.6±3.1%). The increases in Oxygen and the reductions in Carbon on surface of HA-MWCNT relative to raw-MWCNT and milled-MWCNT indicated the introduction of functional oxygenated groups on MWCNT. The HA-MWCNT did not show acute toxicity against D. magna. These results suggest that the coating changes the MWCNT surface, resulting in a material with potential to metal remediation, prepared without oxidizing acids and that did not show toxicity on D. magna

Nanoecotoxicity and uptake of TiO2@MWCNT hybrid material on Danio rerio embryos.

A process that is being widely used for environmental remediation is photocatalysis. The use of nanotechnology can highly improve this field, and there is already a wide range of nanomaterials employed in photocatalytic research and applications. A material that has been highlighted in this field is the TiO2@MWCNT, this combination increase the photocatalytic efficiency, and therefore being an extremely effective method for remediation of contaminants. Due to the importance of these hybrid materials, the production of such particles has been encouraged. However, concerns about their toxicity and safety when released into the environment should be considered. Therefore, to understand the role of TiO2@MWCNT in the environment, our main objective was to study the photocatalytic activity and toxicity of TiO2@MWCNT composite on Danio rerio embryos (zebrafish). For this purpose, TiO2@MWCNT nanomaterial was synthetized, by mechanical mixing method, and an early life stage assay was performed with zebrafish embryos. The parameters assessed were acute toxicity, hatching rate, growth, yolk sac size, and the sarcomere length. In addition, we employed ?-probe X-ray fluorescence spectroscopy to observe if nanoparticles were being uptake by zebrafish larvae. Also, the photocatalytic efficiency of the TiO2@MWCNT was assessed through indigo blue dye degradation using UV-Vis spectroscopy. TiO2@MWCNT characterization was performed by SEM, TEM and TGA analysis. Our results shown that the preparation method was efficient to loaded the TiO2 on the surface of MWCNT, and the composite was more photocatalytic than TiO2. Besides, no acute toxicity, nor sublethal effects in Danio rerio embryos was observed until 100 mg L-1. Nevertheless, µ-XRF showed that the larvae were ingesting the nanoparticle. In conclusion, TiO2@MWCNT is a promising material for environmental remediation, presenting high efficiency and low toxicity

Importância da padronização do meio de exposição nas avaliações nanoecotoxicológicas.

As propriedades dos nanomateriais (NMs) dependem, dentre outras, da composição iônica do meio de exposição. Porém, a descrição do mesmo é negligenciada em diversas publicações na área. Apesar de existirem protocolos padronizados para estudos ecotoxicológicos com embriões de Danio rerio, o meio de exposição pode variar. O objetivo deste trabalho foi avaliar a influência da composição do meio de exposição na toxicidade de NMs. Estudou-se o carvão ativo nanoestruturado - sem (ACBP) e com nanopartículas de prata (ACBP-AgNPs) - sintetizado no LNNano. Esse novo material alia a capacidade de adsorção do carvão com a atividade antimicrobiana da prata, podendo ser utilizado na remediação ambiental. Embriões de D. rerio foram expostos aos NMs em concentrações de 1 a 100 mg/L, em dois diferentes meios de exposição: M1 (0,3 mS/cm, pH 7,5) e M2 (3 mS/cm, pH 7,5). A exposição em M2 apresentou maior toxicidade [CL50-96h = 25,83 (22,2-30,5) mg/L] do que em M1 [ CL50-96h de 90,09 (73,40-113,5) mg/L]. A toxicidade observada está relacionada às AgNPs, visto que a exposição a ACBP não apresentou toxicidade. A maior concentração de íons cloreto (17,9.10-4 mol/L) presente em M2 com relação a M1 (5.10-5 mol/L) pode estar relacionada à toxicidade observada. A literatura relata haver dissolução parcial das AgNPs na presença de cloretos, com formação de cloreto de prata. Nossos resultados evidenciam a necessidade de padronização dos meios de exposição em estudos nanotoxicológicos

Ecotoxicidade de nanotubos de carbono revestidos com ácido húmico sobre Daphnia magna.

Devido à crescente produção e aplicação de nanomateriais em diversos setores industriais, a avaliação de sua ecotoxicidade é fundamental. Todavia, a estabilidade coloidal é um dos fatores que mais a influenciam, desempenhando efeitos substanciais sobre a biodistribuição e destino destes materiais no ambiente aquático. Nanotubos de carbono de paredes múltiplas foram revestidos com ácido húmico por um processo mecanoquímico, sem uso de solventes químicos, com a finalidade de alcançar uma dispersão coloidal adequada para estudos de ecotoxicidade de nanotubos de carbono. Ensaios de ecotoxicidade aguda (48 h) foram realizados com o microcrustáceo Daphnia magna nas concentrações de 0,1;1,0; 5,0 e 10 mg/L de nanotubos revestidos. A estabilidade coloidal foi monitorada por meio da análise do tamanho das partículas (diâmetro hidrodinâmico) e potencial Zeta (carga superficial) no meio de cultivo dos organismos (água reconstituída). O diâmetro hidrodinâmico e o potencial Zeta das partículas mantiveram-se constantes durante as 48 horas de exposição, e não foram observados efeitos de ecotoxicidade aguda. Microscopia de força atômica, espectroscopia ultravioleta-visível e termogravimetria foram empregadas para a caracterização dos nanotubos. Concluímos que o método/processo de dispersão empregado foi eficiente para proporcionar estabilidade coloidal ao nanomaterial em água reconstituída, permitindo assim, uma avaliação correta de sua ecotoxicidade sobre D. magna

TiO2-carbon nanotubes nanohybrid toxicity in Danio rerio embryo.

Recent findings indicate that the combination of titanium dioxide (TiO2) with carbon nanotubes (CNT) increase the photocatalytic efficiency. Due to the importance of these new technologies, the production of such particles has been encouraged. However, concerns about their toxicity and safety when released into the environment are considerable. Therefore, to understand the role of TiO2-MWCNT in the environment, our gold was to synthesize TiO2-MWCNT nanomaterial, by mechanical mixing method, and evaluate its toxicity. For this purpose, an early life stage assay was performed with Danio rerio embryos. The parameters assessed were acute toxicity, hatching rate and growth. Also, the photocatalytic efficiency of the TiO2-MWCNT was assessed through indigo blue dye degradation. Characterization was performed by electron transmission microscopy. The synthesis was efficient to loaded the TiO2 on the surface of MWCNT, and the composite was more photocatalytic than TiO2. Also, there was no acute toxicity, nor sublethal effects in Danio rerio embryos, until 100 mg L?1. Therefore, the nanohybrid TiO2-MWCNT is a promising material, presenting high efficiency and low toxicity

Endophytic actinomycetes from spontaneous plants of Algerian Sahara: indole-3-acetic acid production and tomato plants growth promoting activity

Twenty-seven endophytic actinomycete strains were isolated from five spontaneous plants well adapted to the poor sandy soil and arid climatic conditions of the Algerian Sahara. Morphological and chemotaxonomical analysis indicated that twenty-two isolates belonged to the Streptomyces genus and the remaining five were non- Streptomyces. All endophytic strains were screened for their ability to produce indole-3-acetic acid (IAA) in vitro on a chemically defined medium. Eighteen strains were able to produce IAA and the maximum production occurred with the Streptomyces sp. PT2 strain. The IAA produced was further extracted, partially purified and confirmed by thin layer chromatography (TLC) analysis. The 16S rDNA sequence analysis and phylogenetic studies indicated that strain PT2 was closely related to Streptomyces enissocaecilis NRRL B 16365T, Streptomyces rochei NBRC 12908T and Streptomyces plicatus NBRC 13071T, with 99.52 % similarity. The production of IAA was affected by cultural conditions such as temperature, pH, incubation period and L-tryptophan concentration. The highest level of IAA production (127 lg/ml) was obtained by cultivating the Streptomyces sp. PT2 strain in yeast extract-tryptone broth supplemented with 5 mg L-tryptophan/ ml at pH 7 and incubated on a rotary shaker (200 rpm) at 30°C for 5 days. Twenty-four-hour treatment of tomato cv. Marmande seeds with the supernatant culture of Streptomyces sp. PT2 that contained the crude IAA showed the maximum effect in promoting seed germination and root elongation

Avaliação da toxicidade do nanomaterial hibrido tio2@mwcnt em embri.

A aplicação do nanomaterial hibrido de TiO2 e CNT vem crescendo consideravelmente, isso principalmente devido a sua alta eficiência fotocatalítica, no entanto, ainda não existem estudos que abordem a toxicidade deste material. Portanto, esse estudo tem o objetivo de comparar e avaliar a toxicidade no nano-hibrido TiO2@MWCNT e das nanopartículas de TiO2 em diferentes condições de exposição (com e sem luz UV). A síntese do nanomaterial hibrido foi feita através da moagem de TiO2 e MWCNT comercial. A caracterização foi feita através de TEM, MEV e DLS. Para a avaliação toxicológica foram utilizados ensaios de toxicidade com embrião de Danio rerio, os parâmetros analisados foram, mortalidade, taxa de eclosão, tamanho da larva, tamanho do saco vitelínico e tamanho do sarcômero. Adicionalmente, foi avaliado a internalização do nanomaterial nas larvas através da espectroscopia de micro fluorescência de raios-x. Não foi observado toxicidade aguda e efeitos subletais para a exposição de 100 mg L-1 de TiO2@MWCNT. No entanto, para as nanopartículas de TiO2 foram observados efeitos subletais significativos para a taxa de eclosão, tamanho das larvas e tamanho do saco vitelínico. Também foi observada a ingestão das partículas de TiO2 e TiO2@MWCNT pelas larvas. ?- The applications of TiO2 and carbon nanotubes (CNT) hybrids have been grown considerably, due to their enhanced photocatalytic efficiency, however, to our knowledge, there are no reports available in literature to the scientific community about their toxicity. Therefore, this study aims to compare the toxicity of TiO2 nanoparticles and TiO2-MWCNT composites under different exposure conditions (with and without UV light exposure). The hybrid nanomaterial was synthesized by milling commercial TiO2 and MWCNT. The Characterization were performed by TEM, MEV, TGA and DLS. The toxicity assay was performed with Danio rerio embryos, the parameters assessed were acute toxicity, hatching rate, growth, yolk sac size, and sarcomere length. In addition, ?-probe X-ray fluorescence spectroscopy was employed to observe if nanoparticles are being uptaken by zebrafish larvae. Neither TiO2 nanoparticles nor TiO2-MWCNT composites present acute toxicity to the embryos and larvae of zebrafish until 100 mg L-1. Moreover, only TiO2 nanoparticles present sublethal effects (with and without UV light exposure) on D. rerio embryos. Nevertheless, µ-XRF showed that the larvae were ingesting the TiO2 nanoparticles and the composites

Effect of diazoxide on Friedreich ataxia models

Friedreich ataxia (FRDA) is an inherited recessive disorder caused by a deficiency in the mitochondrial protein frataxin. There is currently no effective treatment for FRDA available, especially for neurological deficits. In this study, we tested diazoxide, a drug commonly used as vasodilator in the treatment of acute hypertension, on cellular and animal models of FRDA. We first showed that diazoxide increases frataxin protein levels in FRDA lymphoblastoid cell lines, via the mammalian target of rapamycin (mTOR) pathway. We then explored the potential therapeutic effect of diazoxide in frataxin-deficient transgenic YG8sR mice and we found that prolonged oral administration of 3 mpk/d diazoxide was found to be safe, but produced variable effects concerning efficacy. YG8sR mice showed improved beam walk coordination abilities and footprint stride patterns, but a generally reduced locomotor activity. Moreover, they showed significantly increased frataxin expression, improved aconitase activity, and decreased protein oxidation in cerebellum and brain mitochondrial tissue extracts. Further studies are needed before this drug should be considered for FRDA clinical trials

Enacting Resilience: A Performative Account of Governing for Urban Resilience

Resilience is an increasingly important urban policy discourse that has been taken up at a rapid pace. Yet there is an apparent gap between the advocacy of social-ecological resilience in scientific literature and its take-up in policy discourse on the one hand, and the demonstrated capacity to govern for resilience in practice on the other. This paper explores this gap by developing a performative account of how social-ecological resilience is dealt with in practice through case study analysis of how protection of biodiversity was negotiated in response to Melbourne’s recent metropolitan planning initiative. It is suggested that a performative account expands the possible opportunities for governing for social-ecological resilience beyond the concept’s use as a metaphor, measurement, cognitive frame or programmatic statement of adaptive management/co-management and has the potential to emerge through what has been called the everyday ‘mangle of practice’ in response to social-ecological feedback inherent to policy processes