Effect of the Size and Shape of Dendronized Iron Oxide Nanoparticles Bearing a Targeting Ligand on MRI, Magnetic Hyperthermia, and Photothermia Properties—From Suspension to In Vitro Studies

Functionalized iron oxide nanoparticles (IONPs) are increasingly being designed as a theranostic nanoplatform combining specific targeting, diagnosis by magnetic resonance imaging (MRI), and multimodal therapy by hyperthermia. The effect of the size and the shape of IONPs is of tremendous importance to develop theranostic nanoobjects displaying efficient MRI contrast agents and hyperthermia agent via the combination of magnetic hyperthermia (MH) and/or photothermia (PTT). Another key parameter is that the amount of accumulation of IONPs in cancerous cells is sufficiently high, which often requires the grafting of specific targeting ligands (TLs). Herein, IONPs with nanoplate and nanocube shapes, which are promising to combine magnetic hyperthermia (MH) and photothermia (PTT), were synthesized by the thermal decomposition method and coated with a designed dendron molecule to ensure their biocompatibility and colloidal stability in suspension. Then, the efficiency of these dendronized IONPs as contrast agents (CAs) for MRI and their ability to heat via MH or PTT were investigated. The 22 nm nanospheres and the 19 nm nanocubes presented the most promising theranostic properties (respectively, r2 = 416 s−1·mM−1, SARMH = 580 W·g−1, SARPTT = 800 W·g−1; and r2 = 407 s−1·mM−1, SARMH = 899 W·g−1, SARPTT = 300 W·g−1). MH experiments have proven that the heating power mainly originates from Brownian relaxation and that SAR values can remain high if IONPs are prealigned with a magnet. This raises hope that heating will maintain efficient even in a confined environment, such as in cells or in tumors. Preliminary in vitro MH and PTT experiments have shown the promising effect of the cubic shaped IONPs, even though the experiments should be repeated with an improved set-up. Finally, the grafting of a specific peptide (P22) as a TL for head and neck cancers (HNCs) has shown the positive impact of the TL to enhance IONP accumulation in cells.

In situ liquid transmission electron microscopy reveals self-assembly-driven nucleation in radiolytic synthesis of iron oxide nanoparticles in organic media

We have investigated the early stages of the formation of iron oxide nanoparticles from iron stearate precursors in the presence of sodium stearate in an organic solvent by in situ liquid phase transmission electron microscopy (IL-TEM). Before nucleation, we have evidenced the spontaneous formation of vesicular assemblies made of iron polycation-based precursors sandwiched between stearate layers. Nucleation of iron oxide nanoparticles occurs within the walls of the vesicles, which subsequently collapse upon the consumption of the iron precursors and the growth of the nanoparticles. We then evidenced that fine control of the electron dose, and therefore of the local concentration of reactive iron species in the vicinity of the nuclei, enables controlling crystal growth and selecting the morphology of the resulting iron oxide nanoparticles. Such a direct observation of the nucleation process templated by vesicular assemblies in a hydrophobic organic solvent sheds new light on the formation process of metal oxide nanoparticles and therefore opens ways for the synthesis of inorganic colloidal systems with tunable shape and size.

A Confinement-Driven Nucleation Mechanism of Metal Oxide Nanoparticles Obtained via Thermal Decomposition in Organic Media

Thermal decomposition is a very efficient synthesis strategy to obtain nanosized metal oxides with controlled structures and properties. For the iron oxide nanoparticle synthesis, it allows an easy tuning of the nanoparticle's size, shape, and composition, which is often explained by the LaMer theory involving a clear separation between nucleation and growth steps. Here, the events before the nucleation of iron oxide nanocrystals are investigated by combining different complementary in situ characterization techniques. These characterizations are carried out not only on powdered iron stearate precursors but also on a preheated liquid reaction mixture. They reveal a new nucleation mechanism for the thermal decomposition method: instead of a homogeneous nucleation, the nucleation occurs within vesicle-like-nanoreactors confining the reactants. The different steps are: 1) the melting and coalescence of iron stearate particles, leading to "droplet-shaped nanostructures" acting as nanoreactors; 2) the formation of a hitherto unobserved iron stearate crystalline phase within the nucleation temperature range, simultaneously with stearate chains loss and Fe(III) to Fe(II) reduction; 3) the formation of iron oxide nuclei inside the nanoreactors, which are then ejected from them. This mechanism paves the way toward a better mastering of the metal oxide nanoparticles synthesis and the control of their properties.

Unveiling the role of surface, size, shape and defects of iron oxide nanoparticles for theranostic applications

Iron oxide nanoparticles (IONPs) are well-known contrast agents for MRI for a wide range of sizes and shapes. Their use as theranostic agents requires a better understanding of their magnetic hyperthermia properties and also the design of a biocompatible coating ensuring their stealth and a good biodistribution to allow targeting of specific diseases. Here, biocompatible IONPs of two different shapes (spherical and octopod) were designed and tested in vitro and in vivo to evaluate their abilities as high-end theranostic agents. IONPs featured a dendron coating that was shown to provide anti-fouling properties and a small hydrodynamic size favoring an in vivo circulation of the dendronized IONPs. While dendronized nanospheres of about 22 nm size revealed good combined theranostic properties (r₂ = 303 mM s^-1, SAR = 395 W g_Fe^-1), octopods with a mean size of 18 nm displayed unprecedented characteristics to simultaneously act as MRI contrast agents and magnetic hyperthermia agents (r₂ = 405 mM s^-1, SAR = 950 W g_Fe^-1). The extensive structural and magnetic characterization of the two dendronized IONPs reveals clear shape, surface and defect effects explaining their high performance. The octopods seem to induce unusual surface effects evidenced by different characterization techniques while the nanospheres show high internal defects favoring Néel relaxation for magnetic hyperthermia. The study of octopods with different sizes showed that Néel relaxation dominates at sizes below 20 nm while the Brownian one occurs at higher sizes. In vitro experiments demonstrated that the magnetic heating capability of octopods occurs especially at low frequencies. The coupling of a small amount of glucose on dendronized octopods succeeded in internalizing them and showing an effect of MH on tumor growth. All measurements evidenced a particular signature of octopods, which is attributed to higher anisotropy, surface effects and/or magnetic field inhomogeneity induced by tips. This approach aiming at an analysis of the structure-property relationships is important to design efficient theranostic nanoparticles.

Iron Stearate Structures: An Original Tool for Nanoparticles Design

Iron carboxylates are widely used as iron precursors in the thermal decomposition process or considered as in situ formed intermediate precursors. Their molecular and three-dimensional (3D)-structural nature has been shown to affect the shape, size, and composition of the resulting iron oxide nanoparticles (NPs). Among carboxylate precursors, stearates are particularly attractive because of their higher stability to aging and hydration and they are used as additives in many applications. Despite the huge interest of iron stearates, very few studies aimed up to now at deciphering their full metal-ligand structures and the mechanisms allowing us to achieve in a controlled manner the bottom-up NP formation. In this work, we have thus investigated the molecular structure and composition of two iron stearate precursors, synthesized by introducing either two (FeSt₂) or three (FeSt₃) stearate (St) chains. Interestingly, both iron stearates consist of lamellar structures with planes of iron polynuclear complexes (polycations) separated with stearate chains in all-trans conformation. The iron content in polycations was found very different between both iron stearates. Their detailed characterizations indicate that FeSt₂ is mainly composed of [Fe₃-(μ₃-O)St₆·xH₂O]Cl, with no (or few) free stearate, whereas FeSt₃ is a mixture of mainly [Fe₇(μ₃-O(H))₆(μ₂-OH)_xSt_12-2x]St with some [Fe₃(μ₃-O)St₆·xH₂O]St and free stearic acid. The formation of bigger polynuclear complexes with FeSt₃ was related to higher hydrolysis and condensation rates within the iron(III) chloride solution compared to the iron(II) chloride solution. These data suggested a nucleation mechanism based on the condensation of polycation radicals generated by the catalytic departure of two stearate chains from an iron polycation-based molecule.

Small iron oxide nanoparticles as MRI T1 contrast agent: scalable inexpensive water-based synthesis using a flow reactor

Small iron oxide nanoparticles (IONPs) were synthesised in water via co-precipitation by quenching particle growth after the desired magnetic iron oxide phase formed. This was achieved in a millifluidic multistage flow reactor by precisely timed addition of an acidic solution. IONPs (≤5 nm), a suitable size for positive T1 magnetic resonance imaging (MRI) contrast agents, were obtained and stabilised continuously. This novel flow chemistry approach facilitates a reproducible and scalable production, which is a crucial paradigm shift to utilise IONPs as contrast agents and replace currently used Gd complexes. Acid addition had to be timed carefully, as the inverse spinel structure formed within seconds after initiating the co-precipitation. Late quenching allowed IONPs to grow larger than 5 nm, whereas premature acid addition yielded undesired oxide phases. Use of a flow reactor was not only essential for scalability, but also to synthesise monodisperse and non-agglomerated small IONPs as (i) co-precipitation and acid addition occurred at homogenous environment due to accurate temperature control and rapid mixing and (ii) quenching of particle growth was possible at the optimum time, i.e., a few seconds after initiating co-precipitation. In addition to the timing of growth quenching, the effect of temperature and dextran present during co-precipitation on the final particle size was investigated. This approach differs from small IONP syntheses in batch utilising either growth inhibitors (which likely leads to impurities) or high temperature methods in organic solvents. Furthermore, this continuous synthesis enables the low-cost (<£10 per g) and large-scale production of highly stable small IONPs without the use of toxic reagents. The flow-synthesised small IONPs showed high T1 contrast enhancement, with transversal relaxivity (r2) reduced to 20.5 mM-1 s-1 and longitudinal relaxivity (r1) higher than 10 mM-1 s-1, which is among the highest values reported for water-based IONP synthesis.

Micotoxinas na dieta de bovinos de corte: revisão

Esta revisão foi realizada com o objetivo de fazer um breve histórico, caracterizar, descrever as alterações metabólicas, sinais clínicos, métodos de prevenção, controle e detoxificação das principais micotoxinas consumidas por bovinos de corte. Após a descoberta da aflatoxina e dos problemas que esta pode causar para os animais e também em humanos, principalmente câncer, as pesquisas científicas aumentaram ano após ano, e hoje são descritos mais de 18000 metabólitos secundários produzidos por fungos, porém os mais estudados são: aflatoxinas, ocratoxina A, tricotecenos, zearalenona, patulina, fumonisina e alcaloides de Ergot. Os ruminantes de uma forma geral necessitam de maiores concentrações de micotoxinas na dieta quando comparados aos monogástricos para apresentarem sintomas clínicos de intoxicação. Isso acontece pelo fato de que algumas de micotoxinas podem ser parcialmente ou totalmente degradadas pelos microrganismos ruminais. Porém, a fermentação ruminal não resulta necessariamente em inativação da toxina, e a extensão da metabolização depende além do tipo de micotoxina consumida, da espécie animal, idade, sexo, raça, tipo de dieta e consequentemente dos tipos de microrganismos que habitam o rúmen. Além disso, algumas micotoxinas possuem ação antimicrobiana, e podem alterar negativamente o metabolismo ruminal. A presença de micotoxinas na dieta pode afetar além da saúde o desempenho produtivo e reprodutivo o que pode levar a altas perdas econômicas. Assim os sistemas de produção de alimentos para bovinos devem adotar práticas agrícolas que minimizem a produção desses metabólitos.

Unravelling the Thermal Decomposition Parameters for The Synthesis of Anisotropic Iron Oxide Nanoparticles

Iron oxide nanoparticles are widely used as a contrast agent in magnetic resonance imaging (MRI), and may be used as therapeutic agent for magnetic hyperthermia if they display in particular high magnetic anisotropy. Considering the effect of nanoparticles shape on anisotropy, a reproducible shape control of nanoparticles is a current synthesis challenge. By investigating reaction parameters, such as the iron precursor structure, its water content, but also the amount of the surfactant (sodium oleate) reported to control the shape, iron oxide nanoparticles with different shape and composition were obtained, in particular, iron oxide nanoplates. The effect of the surfactant coming from precursor was taking into account by using in house iron stearates bearing either two or three stearate chains and the negative effect of water on shape was confirmed by considering these precursors after their dehydration. Iron stearates with three chains in presence of a ratio sodium oleate/oleic acid 1:1 led mainly to nanocubes presenting a core-shell Fe1-xO@Fe3-xO₄ composition. Nanocubes with straight faces were only obtained with dehydrated precursors. Meanwhile, iron stearates with two chains led preferentially to the formation of nanoplates with a ratio sodium oleate/oleic acid 4:1. The rarely reported flat shape of the plates was confirmed with 3D transmission electronic microscopy (TEM) tomography. The investigation of the synthesis mechanisms confirmed the major role of chelating ligand and of the heating rate to drive the cubic shape of nanoparticles and showed that the nanoplate formation would depend mainly on the nucleation step and possibly on the presence of a given ratio of oleic acid and chelating ligand (oleate and/or stearate).

[Feline sarcoid in a 1-year-old domestic short-haired cat caused by bovine papillomavirus type 14 in Switzerland]

INTRODUCTION

A 1-year- old domestic short haired cat, living on a farm in Switzerland, was presented to the veterinarian with a 5 cm in diameter mass, bulging from her left nostril. The mass was only incompletely removed because of its unfavourable location. Histologically, the lesion consisted of an infiltrative growing spindeloid proliferation in close approximation to the epidermis and was diagnosed as a feline sarcoid tumour. The presence of Bovine Papillomavirus type 14 (BPV-14) specific DNA could be identified in the tissue by using two PCR assays. The amplified sequences of 194 and 549 base pairs (bp) were 99% and 100% identical with a virus isolated after autopsy, from a cat with feline sarcoid in the USA. The cat recovered completely after an even incomplete surgical excision and no recurrence could be observed 10 months later.

Dietas insulina-estimulantes para las hembras porcina

Esta revisión bibliográfica tiene como objetivo presentar los efectos de la insulina modulada por la dieta en el rendimiento reproductivo y productivo de las cerdas. La insulina es una hormona que tiene papel de intermediario entre la nutrición y la reproducción, causando la síntesis de gonadotropinas, FSH y LH, a través de efectos directos sobre los ovarios. Los niveles de insulina endógena pueden estar influidos tanto por los nutrientes ingeridos como por la fuente de energía. Los estudios científicos han demostrado que las dietas donde los lípidos son la fuente principal de energía no producen mejoras en la condición corporal de las cerdas reproductoras durante la lactancia y tampoco en el desarrollo reproductivo después del destete. De hecho, puede empeorar la condición catabólica, debido al aumento de grasa en la producción de leche. Por otra parte, aumentar el contenido de carbohidratos durante la lactación puede mejorar el balance de energía, la secreción de gonadotropina y los perfiles de insulina y glucosa. Se ha demostrado que es posible modular los niveles de insulina en plasma mediante el consumo de hidratos de carbono complejos, tales como el almidón, que puede producir picos más prolongados de glucosa en comparación con los carbohidratos simples como dextrosas o sacarosas, promoviendo así el desarrollo folicular de los ovocitos, a partir de la síntesis de la hormona luteinizante a nivel en el ovario.

Divergence of annual and perennial species in the Brassicaceae and the contribution of cis-acting variation at FLC orthologues

Variation in life history contributes to reproductive success in different environments. Divergence of annual and perennial angiosperm species is an extreme example that has occurred frequently. Perennials survive for several years and restrict the duration of reproduction by cycling between vegetative growth and flowering, whereas annuals live for 1 year and flower once. We used the tribe Arabideae (Brassicaceae) to study the divergence of seasonal flowering behaviour among annual and perennial species. In perennial Brassicaceae, orthologues of FLOWERING LOCUS C (FLC), a floral inhibitor in Arabidopsis thaliana, are repressed by winter cold and reactivated in spring conferring seasonal flowering patterns, whereas in annuals, they are stably repressed by cold. We isolated FLC orthologues from three annual and two perennial Arabis species and found that the duplicated structure of the A. alpina locus is not required for perenniality. The expression patterns of the genes differed between annuals and perennials, as observed among Arabidopsis species, suggesting a broad relevance of these patterns within the Brassicaceae. Also analysis of plants derived from an interspecies cross of A. alpina and annual A. montbretiana demonstrated that cis-regulatory changes in FLC orthologues contribute to their different transcriptional patterns. Sequence comparisons of FLC orthologues from annuals and perennials in the tribes Arabideae and Camelineae identified two regulatory regions in the first intron whose sequence variation correlates with divergence of the annual and perennial expression patterns. Thus, we propose that related cis-acting changes in FLC orthologues occur independently in different tribes of the Brassicaceae during life history evolution.

Níveis de fósforo digestível para suínos machos castrados dos 30 aos 50 kg

Realizou-se este estudo com o objetivo de avaliar níveis de fósforo digestível em dietas para suínos machos castrados, com alto potencial para deposição de carne magra, dos 30 aos 50 kg. Foram utilizados 80 suínos, com peso inicial de 31,97 ± 2,5 kg, distribuídos em delineamento de blocos ao acaso, com cinco níveis de fósforo digestível (0,219; 0,257; 0,294; 0,332 e 0,370 %), oito repetições e dois animais por unidade experimental. Os níveis de fósforo não influenciaram (p>0,05) o consumo de ração, ganho de peso e a conversão alimentar. O consumo diário de fósforo digestível aumentou linearmente (p0,05) a profundidade de músculo, área de olho de lombo, espessura de toucinho, percentual e quantidade de carne magra na carcaça. Constatou-se aumento linear (p

Glutamina para frangos de corte criados em ambiente quente

Realizou-se este estudo com o objetivo de avaliar planos de suplementação de glutamina para frangos de corte, de um a 42 dias de idade, criados em ambiente quente. Utilizou-se 690 pintainhos de corte machos da linhagem Cobb distribuídos em delineamento em blocos casualizados com cinco planos de suplementação de glutamina: 0 % de um a 42 dias de idade; 0,5 % de um a 7 dias e 0 % de 8 a 42 dias; 1,0 % de um a 7 dias e 0 % de 8 a 42 dias; 1,0 % de um a 7 dias, 0,5 % de 8 a 14 dias e 0 % de 15 a 42 dias; 1,0 % de um a 7 dias, 1,0 % de 8 a 14 dias, 0,5 % de 15 a 21 dias e 0 % de 22 a 42 dias e 6 repetições de 23 aves cada. Adotou-se o peso inicial das aves como critério de bloqueamento. Os dados obtidos foram submetidos à análise de covariância e quando ocorreram diferenças significativas as médias foram comparadas pelo teste de Tukey a 5 % de probabilidade. Constatou-se que as aves alimentadas com as dietas suplementadas com 1,0 % de glutamina de um a 14 dias e 0,5 % de glutamina de 14 a 21 dias apresentaram maior peso corporal final, ganho de peso e maiores pesos de carcaça, de peito e de dorso. Para aves criadas sob temperaturas elevadas, recomenda-se a suplementação de glutamina de 1,0 % de um a 14 dias e 0,5 % de 14 a 21 dias e 0 % de 22 a 42 dias de idade, a qual proporciona maior peso corporal, ganho de peso, pesos de carcaça e de peito e rendimento de carcaça.

Minerais orgânicos e licopeno na alimentação de poedeiras: desempenho zootécnico e qualidade dos ovos

Objetivou-se avaliar o efeito da utilização de minerais orgânicos e do licopeno em rações para poedeiras sobre o desempenho zootécnico e a qualidade dos ovos. Utilizaram-se 288 poedeiras, distribuídas em DIC em esquema fatorial 2 x 3 (fontes de minerais x níveis de licopeno), com seis tratamentos, seis repetições e oito aves por unidade experimental. As rações experimentais foram: minerais inorgânicos (MI) sem a adição de licopeno; MI com a adição de licopeno (400mg/kg); MI com a adição de licopeno (800mg/kg); minerais orgânicos (MOR) sem a adição de licopeno; MOR com a adição de licopeno (400mg/kg); MOR com a adição de licopeno (800mg/kg). Foram avaliados: consumo de ração, porcentagem de postura, massa dos ovos, conversão alimentar (kg/kg e kg/dz), peso do ovo, porcentagens de casca, albúmen e gema, espessura da casca, gravidade específica, unidade Haugh, índice e coloração de gema, pH do albúmen e da gema. Os minerais orgânicos aumentam o consumo de ração quando associados a níveis de 0 e 800mg de licopeno. A associação de 400mg de licopeno com minerais inorgânicos aumenta o consumo de ração. A adição de minerais orgânicos ou de 400mg de licopeno às rações melhora a porcentagem de postura e massa dos ovos de poedeiras com 58 semanas de idade. A coloração de gema é mais acentuada para as fontes inorgânicas em relação às orgânicas e mais acentuada em rações com 800mg de licopeno. A unidade Haugh é maior em rações sem licopeno e com minerais inorgânicos e em rações com 400mg de licopeno e com minerais orgânicos. Rações com fonte orgânica associada a 800mg de licopeno proporcionam maior unidade Haugh em relação a fonte orgânica sem licopeno.

Mananoligossacarídeo e ß-glucano em dietas de leitões desmamados

Avaliou-se o efeito da suplementação de mananoligossacarídeo, ß-glucano e antibiótico em dietas de leitões machos castrados, durante a fase de creche (21 aos 54 dias de idade), sobre o desempenho, características morfo-histológicas da mucosa intestinal e ocorrência de diarreia. Foram utilizados 368 leitões de mesma linhagem, distribuídos em delineamento inteiramente ao acaso, com quatro tratamentos (1: 330g de mananoligossacarídeo t/ração (oriundos do núcleo), 2: 1.830g de mananoligossacarídeo t/ração (330g oriundos do núcleo + 1.550g da suplementação), 3: 330g de mananoligossacarídeo (oriundos do núcleo) + 500g de ß-glucano t/ração e 4: 330g de mananoligossacarídeo (oriundos do núcleo) + 250g de Colistina t/ração) e quatro repetições com 23 animais por unidade experimental. O desempenho foi avaliado pelo ganho de peso, consumo de ração e conversão alimentar. As características morfo-histológicas da mucosa intestinal estudadas foram altura de vilosidade, profundidade das criptas intestinais, perímetro de vilosidade e a relação altura de vilosidade:profundidade de cripta do duodeno, jejuno e íleo. A ocorrência de diarreia foi observada diariamente pela avaliação de escore fecal. A suplementação de mananoligossacarídeo, β-glucano e antibiótico na dieta de leitões machos castrados, na fase de creche, não influenciaram o desempenho e a ocorrência de diarreia. Maior altura de vilosidade e maior profundidade de criptas no duodeno e íleo foram verificadas nos animais suplementados com ß-glucano. No jejuno foi observado maior perímetro de vilosidade nos animais suplementados com ß-glucano e nos animais que não receberam suplemento adicional na dieta.

Lisina digestível em dietas de baixa proteína para frangos de corte tipo caipira de um aos 28 dias

Avaliou-se a inclusão de diferentes porcentagens de lisina digestível em dietas de baixa proteína para frangos de corte tipo caipira, machos e fêmeas, com idade entre um e 28 dias. Utilizaram-se 792 machos e 792 fêmeas de linhagem comercial, de um dia de idade, distribuídos em delineamento inteiramente ao acaso, em esquema fatorial 2x6 (sexo x porcentagem de lisina digestível: 0,85; 0,90; 0,95; 1,00; 1,05 e 1,10%) com seis repetições de 22 aves. Não foi constatada interação (P>0,05) de sexo versus inclusão de lisina. Observou-se superioridade (P<0,05) dos machos em relação às fêmeas para todas as variáveis avaliadas. O ganho de peso dos frangos diminuiu linearmente (P<0,05) em função do aumento da porcentagem de lisina digestível na dieta e observou-se redução linear (P<0,01) nos consumos de ração e de proteína. O consumo de lisina digestível aumentou linearmente (P<0,01) em função do aumento de sua concentração na dieta. Não houve diferença (P>0,05) para conversão alimentar. Da composição centesimal da carcaça, apenas o percentual de matéria mineral foi influenciada (P<0,05) pela porcentagem de lisina digestível. Conclui-se que 0,85% de lisina para frangos tipo caipira de pescoço pelado atende à exigência nutricional de lisina digestível em dietas com baixa concentração proteica.

Classification of mild cognitive impairment and Alzheimer disease using model-based MR and magnetization transfer imaging

BACKGROUND AND PURPOSE

Early stratification of degenerative processes is a prerequisite to warrant therapeutic options in prodromal Alzheimer disease. Our aim was to investigate differences in cerebral macromolecular tissue composition between patients with AD, mild cognitive impairment, and age- and sex-matched healthy controls by using model-based magnetization transfer with a binary spin-bath magnetization transfer model and magnetization transfer ratio at 1.5 T.

MATERIALS AND METHODS

We investigated patients with de novo AD (n=18), MCI (n=18), and CTRLs (n=18). A region-of-interest analysis of the entorhinal cortex, hippocampal head and body, insula, and temporal neocortex was performed with fuzzy clustering to associate every subregion to a cluster representative for each group.

RESULTS

Cluster analysis achieved a concordance of 0.92 (50 of 54 subjects) between a combination of the calculated mMT parameters (kf,kr,T2r,F,T2f) in the entorhinal cortex and the neuropsychological diagnosis. The sensitivity and specificity for the discrimination of AD from MCI reached 1 and 0.94, with a positive predictive value of 0.95 and a negative predictive value of 1. Compared with mMT, the concordance for MTR was 0.83 (45 of 54 subjects) with a lower specificity of 0.5 and positive predictive value of 0.67 to discriminate patients with AD and MCI.

CONCLUSIONS

mMT imaging detects macromolecule-related alterations and allows an improved classification of patients with early AD and MCI compared with MTR.

Planos nutricionais de lisina para suínos da fase inicial a terminação

Este estudo foi conduzido com o objetivo de avaliar planos nutricionais de lisina para suínos criados em lotes mistos, dos 63 aos 164 dias de idade. Foram utilizados 240 animais, com peso inicial de 24,6±1,5 kg, distribuídos em delineamento de blocos ao acaso com quatro planos nutricionais (A: 1,05-0,88-0,82-0,78-0,78; B: 1,05-0,87-0,80-0,76-0,76; C: 1,05-0,85-0,77-0,71-0,71 e D: 1,05-0,82-0,75-0,70-0,69 % de lisina digestível, respectivamente dos 63 aos 74 dias, dos 75 aos 89 dias, dos 90 aos 111 dias, dos 112 aos 135 dias e dos 136 aos 164 dias), com seis repetições e dez animais cada. Os planos contendo as sequências nutricionais de A e B melhoraram a conversão alimentar dos suínos quando comparados aos demais planos nutricionais. Os suínos alimentados com o plano nutricional contendo a sequência D apresentaram menor peso de carcaça quente. O plano nutricional correspondente a sequência C, respectivamente para suínos dos 63 aos 74 dias, dos 63 aos 89 dias, dos 63 aos 111 dias, dos 63 aos 135 dias e dos 63 aos 164 dias atende as necessidades nutricionais e maximiza o desem-penho e as características de carcaça da fase inicial a terminação.

Susceptibility-weighted MR imaging for diagnosis of capillary telangiectasia of the brain

BACKGROUND AND PURPOSE

BCT is a benign entity, whose appearance on conventional MR imaging makes its differentiation from neoplastic, inflammatory, or subacute ischemic disease challenging. SWI is sensitive to susceptibility effects from deoxyhemoglobin with excellent spatial resolution. Only scarce case reports have described the utility of SWI in cases of BCT. Our aim was to show the diagnostic value of SWI applied to a larger series of cases.

MATERIALS AND METHODS

This was an observational retrospective study of 33 BCTs in 27 consecutive patients examined from August 2009 to January 2011 with MR imaging, including SWI. Morphology, signal intensity characteristics, and additional vascular malformations were analyzed. Preceding or follow-up examinations were available in 18 patients with a median time interval of 14.5 months (range, 2-115 months).

RESULTS

Twenty-five pontine and 8 supratentorial BCTs demonstrated distinct signal-intensity loss on SWI in combination with postcontrast enhancement. Mean lesion diameter was 4.9 mm (range, 1.5-17 mm). Thirty-nine percent showed slight signal-intensity changes on T1 and/or T2; the remainder were isointense to normal brain. In 30%, a prominent draining vessel was observed. Additional cerebral vascular malformations were found in 5 patients.

CONCLUSIONS

SWI represents a valuable tool for confirmation of presumed BCT. Demonstration of signal-intensity loss on SWI in an enhancing focal brain lesion, otherwise unremarkable on conventional MR images, is highly specific for BCT, thus excluding serious pathology and reassuring the patient and referring physician. This is particularly helpful for BCT in less typical locations.

Simulação técnico-econômica da inclusão de ractopamina em dietas de suínos em terminação

Foi realizada simulação técnico-econômica a partir de resultados de publicações para avaliar a inclusão de ractopamina em dietas de suínos em terminação. Foram utilizados 18 artigos, que avaliaram níveis de 0, 5, 10 e/ou 20ppm de ractopamina na dieta, totalizando 2.991 animais. A partir dos resultados técnicos das publicações avaliadas, foram geradas equações que foram utilizadas na simulação do desempenho técnico-econômico. Verificou-se que os custos independem do sistema de receitas do produtor e oscilam de 3 a 6ppm de ractopamina adicionada à dieta. O lucro máximo foi obtido com os níveis de 10 e 12ppm de ractopamina, respectivamente, para os sistemas de receita por peso vivo e por bonificação. Os resultados evidenciam melhor desempenho econômico da utilização de ractopamina, na dieta dos suínos em terminação, pelo sistema de receita por bonificação. As análises de sensibilidade para a variação na receita dos produtores apresentam valores ótimos de 9 a 12ppm de ractopamina, com oscilação de até R$ 49,00/cabeça entre os cenários testados.

Plastidic trnFUUC pseudogenes in North American genus Boechera (Brassicaceae): mechanistic aspects of evolution

The origin and maintenance of a plastidic tandem repeat next to the TRNF (UUC) gene were analyzed in the genus BOECHERA in a phylogenetic context and were compared to published analogous examples that emerged in parallel in the Asteraceae and Juncaceae, respectively. Although we identified some features common to these taxonomic groups with respect to structure and origin of the region, obvious differences were encountered, which argue against a specific mechanism or evolutionary principle underlying the parallel origin and maintenance of the TRNF-tandem repeats in those families. In contrast to the situation in the Asteraceae, no reciprocal recombinant repeat types have been observed in the Brassicaceae. Forty copy types, classified into three groups, were isolated from 103 chloroplast haplotypes of BOECHERA and it was demonstrated that they are composed of four subregions of various origins. We discuss various mutation mechanisms such as DNA replication slippage, and inter- and intrachromosomal recombination which were reported to mediate variation in copy numbers and other types of observed sequence length polymorphism. It is shown that the observed molecular structure of the tandem repeat region did not fully fit the particular patterns expected under a scenario of evolution including any of the known mechanisms. Nevertheless, it appeared that intermolecular unequal crossing-over is most likely the driving force in the evolution of this tandem repeat. However, it remains to be explained, why no reciprocal recombinant copy types have been observed. The reconstructed phylogenetic relationships among copies reflected different evolutionary scenarios as follows: (1) A single and ancient origin of copies pre-dates the radiation of BOECHERA. (2) Parallel expansion and shortening of the tandem repeat within different BOECHERA lineages. (3) Conservation of the first copy, as it was the only one present in all chloroplast haplotypes.

Resposta de suínos em crescimento mantidos em diferentes temperaturas

Foram utilizados 24 suínos machos castrados, distribuídos em delineamento inteiramente ao acaso composto por dois tratamentos e doze repetições, com o objetivo de avaliar o comportamento, respostas fisiológicas e o desempenho dos animais. As temperaturas médias do período experimental foram 21,5oC e 31,3oC, respectivamente, nos ambientes de conforto térmico e de estresse por calor. Suínos sob estresse por calor permaneceram significativamente menos tempo na posição em pé, mais tempo na posição deitado, menos tempo no comedouro, mais tempo no bebedouro, mais tempo na posição deitado no bebedouro e mais tempo dormindo em relação àqueles mantidos sob conforto térmico. Suínos sob estresse por calor apresentaram consumos de energia, proteína, lisina e ração, ganho de peso e conversão alimentar reduzidos e apresentaram menores pesos de órgãos, exceto do estômago, e freqüência respiratória e temperaturas retal e de superfície aumentadas. Suínos sob conforto térmico apresentaram maior eficiência de utilização da proteína e energia e maiores deposições diárias de proteína e gordura na carcaça. Temperaturas que provocam estresse por calor afetam negativamente o comportamento de suínos em crescimento.

Comparison of spatial and temporal pattern for fMRI obtained with BOLD and arterial spin labeling

Functional magnetic resonance imaging (fMRI) is presently either performed using blood oxygenation level-dependent (BOLD) contrast or using cerebral blood flow (CBF), measured with arterial spin labeling (ASL) technique. The present fMRI study aimed to provide practical hints to favour one method over the other. It involved three different acquisition methods during visual checkerboard stimulation on nine healthy subjects: 1) CBF contrast obtained from ASL, 2) BOLD contrast extracted from ASL and 3) BOLD contrast from Echo planar imaging. Previous findings were replicated; i) no differences between the three measurements were found in the location of the activated region; ii) differences were found in the temporal characteristics of the signals and iii) BOLD has significantly higher sensitivity than ASL perfusion. ASL fMRI was favoured when the investigation demands for perfusion and task related signal changes. BOLD fMRI is more suitable in conjunction with fast event related design.

Résultats de la chirurgie des ostéomes du coude chez le cérébro-lésé

PURPOSE OF THE STUDY

Neurogenic paraosteoarthropathy of the elbow is a frequent complication in head injury patients. The functional impairment may be severe. The purpose of this work was to evaluate the efficacy of our medico-surgical approach and to determine indications for surgery.

MATERIAL AND METHODS

We analyzed retrospectively a continuous series of 44 patients (51 elbows) with neurogenic heterotopic new bone of the elbow joint managed from 1993 to 2000. The heterotopic bone had developed on a central deficit limb in 70% of the patients. Flexion-extension was limited in all patients, and pronation-supination in nine. The ulnar nerve was compressed by the heterotopic bone in half of the patients. A 3D reconstruction CT-scan with contrast injection was obtained in all patients. We consider did not the classical criteria for bone maturation to assess operability. Using an adapted approach, we removed the heterotopic new bone to enable complete elbow motion. Associated procedures were performed in fifteen patients due to persistent intraoperative joint stiffness related to muscle-tendon retraction. We did not prescribe diphosphonates or radiotherapy postoperatively.

RESULTS

At 45 months follow-up, one patient had been lost. Relative gain was considered very good in 34 elbows, good in 13 and fair in 3. There were no cases of lost motion. There were no recurrences causing joint limitation, but two of nine cases of radioulnar synostosis recurred.

DISCUSSION

Neurogenic paraosteopathy of the elbow impairs joint function and may lead to ulnar nerve compression. The goal of surgery is to improve function. The analysis of our results show that early surgery yields good results without complementary treatment, irrespective of the patient's overall functional deficit or cognitive status and irrespective of the localization of the hetertopic bone. The essential prognostic factor for the quality results is the neurological status of the limb, particularly the degree of spasticity and muscle-tendon retraction.

Exigência de aminoácidos sulfurados digestíveis para suínos machos castrados mantidos em ambiente termoneutro dos 15 aos 30kg

Determinou-se a exigência de aminoácidos sulfurados para suínos machos castrados, mantidos em ambiente termoneutro, dos 15 aos 30kg. Utilizaram-se 70 leitões mestiços, distribuídos em delineamento experimental de blocos ao acaso, com cinco tratamentos (0,465; 0,511; 0,558; 0,605 e 0,652% de metionina + cistina digestível), sete repetições e dois animais por repetição. As rações experimentais e a água foram fornecidas à vontade. A temperatura no interior da sala foi mantida em 21,8±0,4ºC e a umidade relativa, em 73,8±4,9%. Os níveis de metionina + cistina digestível da dieta influenciaram de forma quadrática o ganho de peso diário, que aumentou até o nível de 0,596%, e a conversão alimentar, que reduziu até o nível de 0,627%. O consumo de ração dos animais não variou com os tratamentos. Os tratamentos influenciaram a deposição de proteína na carcaça, que aumentou de forma quadrática até o nível de 0,630%, enquanto a de gordura não variou. A exigência de aminoácidos sulfurados digestíveis para suínos machos castrados, mantidos em ambiente termoneutro, dos 15 aos 30 kg, é de 0,63%, correspondente à relação metionina + cistina digestível:lisina digestível de 67%, para máximo desempenho e composição de ganho.

Locally induced hypothermia for treatment of acute ischaemic stroke: a physical feasibility study

During the treatment of stroke by local intra-arterial thrombolysis (LIT) it is frequently possible to pass the blood clot with a micro-catheter, allowing perfusion of brain tissue distally to the occlusion. This possibility allows for new early treatments of ischaemic brain tissue, even before the blood clot has been removed. One potential new approach to preserve brain tissue at risk may be locally induced endovascular hypothermia. Physical parameters such as the required micro-catheter input pressure, output velocity and flow rates, and a heat exchange model, applicable in the case of a micro-catheter placed within a guiding catheter, are presented. Also, a simple cerebral temperature model is derived that models the temperature response of the brain to the perfusion with coolant fluids. Based on this model, an expression has been derived for the time needed to reach a certain cerebral target temperature. Experimental in vitro measurements are presented that confirm the usability of standard commercially available micro-catheters to induce local hypothermia of the brain. If applied in vivo, the model predicts a local cooling rate of ischaemic brain tissue of 300 g of approximately 1 degrees C in 1 min, which is up to a factor 30-times faster than the time-consuming systemic hypothermia via the skin. Systemic body temperature is only minimally affected by application of local hypothermia, thus avoiding many limitations and complications known in systemic hypothermia.

Multiresolution fuzzy clustering of functional MRI data

Recent developments in the analysis of functional MRI data reveal a shift from hypothesis-driven statistical tests to unsupervised strategies. One of the most promising approaches is the fuzzy clustering algorithm (FCA), whose potential to detect activation patterns has already been demonstrated. But the FCA suffers from three drawbacks: first the computational complexity, second the higher sensitivity to noise and third the dependence on the random initialization. With the multiresolution approach presented here, these weak points are significantly improved, as is demonstrated in our tests with simulated and real functional MRI data.

Diffusion-weighted MRI in acute spinal cord ischaemia

Acute spinal cord ischaemia is often undetectable with conventional MRI. Diffusion-weighted MRI (DWI) has been difficult to use in the spine because of susceptibility artefacts. We assessed the diagnostic value of echoplanar DWI for early confirmation of spinal cord ischaemia. We performed conventional MRI and DWI in two men and three women, aged 54-75 years with clinically suspected acute spinal cord ischaemia. Imaging was performed 9-46 h after the onset of symptoms, and 2-9 days later to assess the extent of ischaemic signal change. Spatial resolution of DWI within the spine using standard equipment was poor, but in all patients, early DWI revealed areas of high signal indicating decreased diffusion, confirmed by measurement of apparent diffusion coefficients. Follow-up MRI showed high signal on T2-weighted images and contrast enhancement at the expected levels. Neurological deficits corresponded with radiological findings in four patients: various syndromes, including isolated bilateral weakness or sensory change and combined deficits, were found. Echoplanar DWI may be helpful for confirmation of spinal cord ischaemia in the acute stage, but follow-up T2-weighted images have superior spatial resolution and correlation with clinical findings and lesion extent.

[Surgical treatment of orthopedic deformities due to spasticity in the lower limb]

Orthopedic deformities in the lower limb concern all joints (hip, knee, ankle, foot) with a wide range of clinical forms. Spasticity, contracture, stiffness, laxity, neurological deficit are assessed to establish the surgical procedure. Surgical techniques are adapted to the goals that are detailed with the patient and his family: standing, transferring, walking, hygiene, devices (shoes, orthosis, canes, wheelchair). Surgical procedures can associate: lengthening of contractured muscles (tenotomy with or without sutures, fractional lengthening at the musculo-tendinous junction or desinsertion), strengthening of antagonists (passive or active tendon transfer) and correction of joint deformity (arthrolysis, arthrodesis, arthroplasty). In adults, the most common deformities are the equinus or equinovarus foot, toe curling, hip adductum, knee flessum. Talus or knee recurvatum are less frequently observed. The association of various deformities raises questions concerning the hierarchy of surgical procedure, from an anatomical point of view (do we start with proximal or distal joint first?) as from chronological concerns (shall we do one or more procedures?). Pluridisciplinary assessment using neurological anesthetic blocs and dynamic EMG or gait analysis is necessary to detail the aims of surgery and choose the surgical procedures.

[Clinical evaluation of spasticity]

Spasticity is one component of the upper motor neurone syndrome. Unlike motor deficit and co-contraction, spasticity is responsive to treatment. Thus it receives more attention than the other features of the upper motor neuron syndrome. In order to treat correctly the patients, we need to know expectations of the patient and family. Detailed clinical evaluation including functional analysis is necessary to determine whether the objectives are reasonable. This evaluation is not always very easy because of complex clinical features. Simply aiming to reduce spasticity is not a final treatment goal. There must be a purpose behind it. It is actually very difficult to evaluate functional effect of spasticity treatments. Few studies show a real functional improvement. Yet patients are satisfied with the results and the goals are often achieved. One explanation is that functional scales usually used do not fit to the spasticity problem.

Slow rhythmic oscillations in intracranial CSF and blood flow: registered by MRI

Since Lundberg first described slow oscillations as so called B-waves during ICP-monitoring, similar oscillations have been found in various physiological systems. Thus, the detection of slow waves in intracranial CSF- and blood-flow with MR-techniques seemed very likely. We examined the interventricular CSF-flow and cerebral blood flow of 11 healthy volunteers with dynamic echo-planar imaging by simultaneous registration of respiration and peripheral pulse. The spectral analysis was restricted to slow waves, which were divided into B-waves (0.008-0.05 Hz), Mayer- or C-waves (0.05-0.15 Hz) and respiration-related waves (0.15-0.6 Hz). In the CSF, the integrated amplitude of B-waves accounted for 18.2%, Mayer- or C-waves for 26.9% and respiration-related waves for 55.0%. Proportional values were recorded in the artery and peripheral pulse. In the venous sinus, a higher percentage of B- and Mayer-/C-waves and a lower percentage of respiration related waves were found. In conclusion, with MR-EPI technique, slow rhythmic oscillations in the cerebral blood- and CSF-flow can be analysed non-invasively and independently from the cardiac cycle. The comparable distribution of slow waves in the pulse, arteries and CSF may reflect an origin in autoregulation, whereas divergent patterns like in the incompressible venous sinus may be of a passive origin.

Apparent diffusion coefficient mapping of infarcted tissue and the ischaemic penumbra in acute stroke

MRI assessment of diffusion changes in acute cerebral ischaemia necessitates analysis of the apparent diffusion coefficient (ADC). We used the concept of relative weighted mean ADC (rwmADC) to obtain an accurate estimate of the extent of infarcted tissue. We studied ten patient with of acute ischaemic stroke, using diffusion- and perfusion- weighted MRI. The rwmADC was used to calculate a corrected ADC-lesion volume (DLVR), which was compared with the diffusion-lesion volume (DLV), initial perfusion lesion volumes and the follow-up infarct volume on T2-weighted images. We looked at correlations between the MRI and clinical findings. DLVR was closest to the final infarct size and had the best clinicoradiological correlation (r=0.77). Weighting the mean ADC within the ischaemic and normal parenchyma can give a more correct estimate of the volume of infarcted brain parenchyma, thus improving the definition of the penumbra.

Diffusion and perfusion MRI for the localisation of epileptogenic foci in drug-resistant epilepsy

Drug-resistant epilepsy is an important clinical challenge, both diagnostically and therapeutically. More and more surgical options are being considered, but precise presurgical assessment is necessary. We prospectively studied eight patients with drug-resistant epilepsy, who underwent clinical examination, single photon emission computed tomography (SPECT) and interictal MRI, including diffusion- and perfusion-weighted echoplanar sequences. Lesions suspected on SPECT of being epileptogenic showed mild hypoperfusion, while the diffusion-weighted MRI (DWI) revealed increased apparent diffusion coefficients relative to the other side. However, these abnormalities were not visible on the corresponding maps. We showed that DWI and perfusion-weighted MRI could be used confirm the characteristics and site of an epileptogenic area in patients with drug-resistant epilepsy.

Focal status epilepticus: follow-up by perfusion- and diffusion MRI

Diffusion-weighted MRI demonstrated bright right temporoparietal cortex, right hippocampus, and left cerebellum in a 63-year-old female suffering a focal convulsive status epilepticus. Hyperperfusion was noted in the right temporoparietal region. Two days later, a tendency to normalization of most of the diffusion and perfusion changes was noted, apart from the right hippocampus which became brighter on diffusion- and T2-weighted images. On the tenth day the apparent diffusion coefficient was slightly elevated, getting brighter on T2-weighted images with suspected mild post-contrast enhancement. We postulate that the discharging right hippocampus suffered cytotoxic edema, which later progressed to cell damage.

Identification and characterization of a mammalian enzyme catalyzing the asymmetric oxidative cleavage of provitamin A

In vertebrates, symmetric versus asymmetric cleavage of beta-carotene in the biosynthesis of vitamin A and its derivatives has been controversially discussed. Recently we have been able to identify a cDNA encoding a metazoan beta,beta-carotene-15,15'-dioxygenase from the fruit fly Drosophila melanogaster. This enzyme catalyzes the key step in vitamin A biosynthesis, symmetrically cleaving beta-carotene to give two molecules of retinal. Mutations in the corresponding gene are known to lead to a blind, vitamin A-deficient phenotype. Orthologs of this enzyme have very recently been found also in vertebrates and molecularly characterized. Here we report the identification of a cDNA from mouse encoding a second type of carotene dioxygenase catalyzing exclusively the asymmetric oxidative cleavage of beta-carotene at the 9',10' double bond of beta-carotene and resulting in the formation of beta-apo-10'-carotenal and beta-ionone, a substance known as a floral scent from roses, for example. Besides beta-carotene, lycopene is also oxidatively cleaved by the enzyme. The deduced amino acid sequence shares significant sequence identity with the beta,beta-carotene-15,15'-dioxygenases, and the two enzyme types have several conserved motifs. To establish its occurrence in different vertebrates, we then attempted and succeeded in cloning cDNAs encoding this new type of carotene dioxygenase from human and zebrafish as well. As regards their possible role, the apocarotenals formed by this enzyme may be the precursors for the biosynthesis of retinoic acid or exert unknown physiological effects. Thus, in contrast to Drosophila, in vertebrates both symmetric and asymmetric cleavage pathways exist for carotenes, revealing a greater complexity of carotene metabolism.

Analysis of the blind Drosophila mutant ninaB identifies the gene encoding the key enzyme for vitamin A formation invivo

Visual pigments (rhodopsins) are composed of a chromophore (vitamin A derivative) bound to a protein moiety embedded in the retinal membranes. Animals cannot synthesize the visual chromophore de novo but rely on the uptake of carotenoids, from which vitamin A is formed enzymatically by oxidative cleavage. Despite its importance, the enzyme catalyzing the key step in vitamin A formation resisted molecular analyses until recently, when the successful cloning of a cDNA encoding an enzyme with beta,beta-carotene-15,15'-dioxygenase activity from Drosophila was reported. To prove its identity with the key enzyme for vitamin A formation in vivo, we analyzed the blind Drosophila mutant ninaB. In two independent ninaB alleles, we found mutations in the gene encoding the beta,beta-carotene-15,15'-dioxygenase. These mutations lead to a defect in vitamin A formation and are responsible for blindness of these flies.

Robustness and diffusion of pointer states

Classical properties of an open quantum system emerge through its interaction with other degrees of freedom (decoherence). We treat the case where this interaction produces a Markovian master equation for the system. We derive the corresponding distinguished local basis (pointer basis) by three methods. The first demands that the pointer states mimic as closely as possible the local nonunitary evolution. The second demands that the local entropy production be minimal. The third imposes robustness on the inherent quantum and emerging classical uncertainties. All three methods lead to localized Gaussian pointer states, their formation and diffusion being governed by well-defined quantum Langevin equations.