Influência da velocidade de circulação do leite na adesão de Pseudomonas aeruginosa sobre aço inoxidável

A influência da velocidade de circulação do leite na adesão bacteriana de Pseudomonas aeruginosa foi avaliada em teste de uso simulado por meio de um modelo de circuito de processamento de leite. O circuito é composto por uma tubulação de aço inoxidável AISI 304, com 1,9 cm de diâmetro e 5,8 m de comprimento, além de um tanque de 25 L, utilizado como reservatório do produto e das soluções sanitizantes. O reservatório foi acoplado a uma bomba centrífuga de ½ HP, para impulsionar o alimento ou soluções de higienização pelo sistema equipado com cupons de prova em aço inoxidável nas formas cilíndrica, cotovelo 90º e T. As velocidades de circulação foram de 0,5, 1,0 e 1,5 m.s-1, correspondentes a fluxo turbulento com número de Reynolds de 14.000, 28.000 e 42.000, respectivamente. Quando se utilizou velocidade de 0,5 m.s-1, permaneceram aderidas à superfície 10,7% das células. Já nas velocidades e 1,0 e 1,5 m.s-1 as porcentagens de adesão foram de 5,36 e 4,9%, respectivamente, o que demonstra uma menor remoção de células aderidas à medida que o fluxo diminui, permitindo assim que mais células permaneçam aderidas na linha de produção, o que pode favorecer a formação de biofilmes.

Effect of huitlacoche (Ustilago maydis DC Corda) paste addition on functional, chemical and textural properties of tortilla chips

AbstractThis study analyzed the addition of huitlacoche paste (HP) in baked tortilla chips (TC), evaluating its effects on functional, physicochemical and structural changes during processing. Two blue corn grains were nixtamalized, stone milled, air dried and milled to obtain flour; commercial blue corn flour (TM1) and commercial TC (TM2) were used as controls. Additions of 0, 3, 6 and 9% of HP were formulated; masas were prepared at 55% moisture content (MC), precooked and baked in an industrial machine. TC crispiness was influenced by grain characteristics and percentage of HP. Huitlacoche paste addition caused an increase in total dietary fiber (from 5.27 to 14.54%), total soluble phenolics content (from 17.52 to 37.60 mg GAE/100 g) and antioxidant capacity (from 6.74 to 7.98 μmol TE/g) in TC. Results suggest that tortilla chips added with huitlacoche can be an alternative to prepare this traditional edible fungus and produce healthier snacks, not fried and enriched with bioactive compounds.

Aspectos clínicos da doença renal policística autossômica recessiva DRPAR

INTRODUÇÃO: A Doença Renal Policística Autossômica Recessiva (DRPAR) é uma causa importante de morbidade e mortalidade pediátricas, com um espectro variável de manifestações clínicas. MÉTODOS: A apresentação e evolução clínica de 25 pacientes (Pts) foram analisadas através da revisão de prontuários, aplicando-se os formulários propostos por Guay-Woodford et al. As morbidades associadas à doença foram avaliadas quanto à frequência e à idade de manifestação. RESULTADOS: A idade média de diagnóstico foi de 61,45 meses (0 a 336,5 meses), com distribuição similar entre os sexos (52% dos pts do sexo feminino). Houve histórico familiar da doença em 20% dos casos (5/25), com dois casos de consanguinidade. Na análise inicial, diagnosticou-se hipertensão arterial (HAS) em 56% dos Pts (14/25); doença renal crônica estágio > 2 (DRC > 2) em 24% (6/25); infecções do trato urinário (ITU) em 40% (10/25) e hipertensão portal (HP) em 32% dos casos (8/25). Das ultrassonografias abdominais iniciais, 80% demonstraram rins ecogênicos com cistos grosseiros e 64% detectaram fígado e vias biliares normais. Inibidores da ECA foram utilizados em 36% dos Pts, betabloqueadores em 20%, bloqueadores de canais de cálcio em 28% e diuréticos em 36% dos casos. Na análise final, após um tempo de acompanhamento médio de 152,2 meses (29,8 a 274,9 meses), HAS foi diagnosticada em 76% dos Pts, DRC > 2 em 44%, ITU em 52% e HP em 68%. CONCLUSÃO: As altas morbidade e mortalidade associadas à DRPAR justificam a construção de um banco de dados internacional, visando ao estabelecimento de um tratamento de suporte precoce.

Associação entre gamopatia monoclonal de significado indeterminado e hiperparatireoidismo primário no diagnóstico diferencial das hipercalcemias - Relato de caso

A gamopatia monoclonal de significado indeterminado (GMSI) é uma doença pré-maligna rara assintomática, definida por uma concentração de imunoglobulina monoclonal no soro menor que 3 g/dL e uma proporção de células plasmocitárias na medula óssea menor que 10%, na ausência de lesões líticas ósseas, anemia, hipercalcemia e insuficiência renal relacionadas com a proliferação de células plasmáticas monoclonais. O hiperparatireoidismo primário (HP) é uma doença relativamente frequente, afetando aproximadamente um em cada 1000 indivíduos. Alguns trabalhos sugerem que a frequência de HP está aumentada em neoplasias, ampliando o espectro da etiologia da hipercalcemia nesses pacientes. Relata-se, aqui, um caso de paciente de 63 anos admitido para investigação de anemia, parestesias e dores em membros inferiores, além de insuficiência renal. Durante investigação, verificou-se hipercalcemia, pico monoclonal sérico de IgA/lambda, sem critérios para mieloma múltiplo, e adenoma de paratireoide. O mesmo foi submetido à paratireoidectomia, cujo anatomopatológico revelou adenoma de paratireoide. Após a cirurgia, houve retorno dos níveis de cálcio e de função renal ao normal.

Utilizing hemicelluloses – the first step : controlled extraction with hot water

Människor utnyttjar ofta kemi mångsidigt i sitt vardagliga liv utan att närmare tänka på detaljerna. Nuförtiden kan man framställa en ökande mängd av produkter ur förnybara råmaterial och en av de mest mångsidiga nybara råmaterialet i Norden är barrträd. Den lyriska lägerelden eller spiselden och möbler av ved samt papper är en väsentlig del av vardagen. Också livsmedel och läkemedel kan innehålla föreningar ur ved. Ved som råmaterial består av tre huvudkomponenten: cellulosa, som är uppbyggd av druvsockermolekyler är en långkedjad, oförgrenad polymer; lignin, som sammanhåller fibrerna i vedmaterialet som lim samt hemicellulosor, som ofta är uppbyggda av olika sockerarter och är en förgrenad polymer. Följaktligen består vedmaterialet av 70 % socker. I detta arbete har vi koncentrerat på i hemicellulosa och dess extraktion ur gran, samt bestämning av hemicellulosans egenskaper. Den slutliga målsättningen i forskningen var att skapa nya produkter ur gran. Forskning i extraktionens hemligheter eller hur hemicellulosa kan effektivt extraheras i den önskade formen kräver nya typers experimentellasanläggningar och experiment samt matematisk modellering. Den långkedjade hemicellulosan är lämplig för att användas t.ex. i skyddshinnor eller i livsmedel. Medel- och småmolekylär hemicellulosa kan användas som utgångsämne för framställning av bränslen, smörjmedel, sockersyror och alkoholer, av vilka xylitol är mest känd för alla pga hälsobefrämjande effekter. Det är utomordentligt viktigt ur miljöns och energiekonomins synvinkel att sträva efter effektivering av utnyttjandet av den värdefullaste och största naturtillgången, skogen i vårt land, med alla möjliga sätt. Resultaten av denna forskning utnyttjar avsevärt den växande, nya, på skogen baserande biobaseradeindustrin, som framställer nya spetsprodukter samt skapar nya arbetsplatser. ----------------------------------------------------- Ihmiset hyödyntävät usein huomaamattaan kemiaa monipuolisesti jokapäiväisessä elämässä. Nykyään kasvava määrä tuotteista kyetään valmistamaan uusiutuvista raaka-aineista ja yksi monipuolisimmista uusiutuvista luonnonvaroistamme pohjolassa ovat havupuut. Tunnelmallinen nuotio tai takkatuli ja puiset huonekalut sekä paperi ovat olennainen osa arkea. Myös elintarvikkeet ja lääkkeet voivat sisältää puusta peräisin olevia yhdisteitä. Puu materiaalina koostuu rakenteeltaan pääosin kolmesta osasta; selluloosasta, joka on rypälesokerista koostuva pitkäketjuinen haaroittumaton polymeeri, ligniinistä, joka toimii puun koossa pitävänä liima-aineena ja hemiselluloosasta, joka on useista eri sokereista rakentunut haaroittunut polymeeri. Näin ollen puusta 70 % on sokeria. Tässä työssä olemme keskittyneet hemiselluloosaan ja sen uuttamiseen kuusesta, sekä ominaisuuksien kartoittamiseen. Tutkimusaiheen lopullinen tavoite on luoda uusia tuotteita kuusesta. Uuton salojen tutkiminen eli miten hemiselluloosa saadaan tehokkaasti uutettua halutunlaisena vaatii uudenlaisia koelaitteistoja ja kokeita, sekä matemaattista mallintamista. Suurikokoinen hemiselluloosa on sopivaa käytettäväksi esimerkiksi suojakalvoissa tai elintarvikkeissa. Keskikokoista ja pienimolekyylistä hemiselluloosaa voidaan käyttää lähtöaineena valmistettaessa polttoaineita, voiteluaineita, sokerihappoja ja sokerialkoholeja, joista xylitoli on terveysvaikutustensa vuoksi kaikille tuttu. Niin ympäristömme kuin myös energiataloutemme kannalta on ensiarvoisen tärkeää pyrkiä kaikin keinoin tehostamaan maallemme arvokkaan, sekä luonnonvaroistamme yhden suurimman, metsän, vastuullista hyödyntämistä. Tämän tutkimuksen tulokset hyödyntävät merkittävästi maahamme nousevaa uutta metsään pohjautuvaa biojalostusteollisuutta, joka valmistaa uusia huipputuotteita sekä luo työpaikkoja.

Utilização do teste de raios-X na avaliação da qualidade de sementes de canafístula (Peltophorum dubium (Sprengel) Taubert

Sementes de leguminosas florestais, como canafístula, muitas vezes são alvos de injúrias durante sua extração e processamento, além de apresentarem problemas de má-formação do embrião. Estes danos não são comumente detectados, devido à presença de tegumento espesso e duro que impede a visualização das estruturas internas das sementes. O objetivo deste trabalho foi definir a metodologia e verificar a possibilidade de utilização do teste de raios-X, na avaliação dos danos internos em sementes de canafístula, bem como, verificar o efeito desses danos na germinação das sementes. Sementes de três lotes de canafístula foram expostas a radiação em aparelho de raios-X Faxitron HP modelo 43855A por vários tempos e intensidades. Posteriormente, foram divididas em três categorias, de acordo com a anatomia interna visualizada nas radiografias, em sementes cheias, sementes com pequenos danos e sementes com danos severos. Após tratamento para a quebra da dormência, as sementes das diferentes categorias foram submetidas ao teste de germinação. A morfologia interna de sementes de canafístula pode ser visualizadas, com exposição a raios-X por 60 segundos na intensidade de 25 KVp. Os danos na morfologia interna visualizados em radiografias, classificados como severos (mais de 50% da área do embrião danificada) afetam drasticamente a germinação das sementes, justificando sua remoção para promover a melhoria da qualidade física e fisiológica de lotes de sementes de canafístula.

N-tyypin johdepolymeerien tutkimus

Konjugoituneiden polymeerien sähkönjohtavuutta voidaan parantaa useita kertaluokkia varauksensiirtoreaktiona tapahtuvan seostuksen avulla. P-tyypin seostuksessa polymeeri hapettuu osittain ja saa positiivisen varauksen. N tyypin seostuksessa polymeeri taas pelkistyy osittain ja saa negatiivisen varauksen. Monia konjugoituneita polymeerejä on käytetty aukkoja kuljettavana p-tyypin materiaalina, mutta yhtä paljoa ei ole tutkittu elektroneja kuljettavia n-tyypin johdepolymeerejä. Kasvava kiinnostus orgaaniseen elektroniikkaan tekee kuitenkin uusien n-tyypin polymeerimateriaalien kehittämisen tarpeelliseksi. Tutkielmassa käsitellään n-tyypin johdepolymeerejä, niiden valmistusta ja ominaisuuksia sekä niiden hyödyntämistä orgaanisen elektroniikan sovelluksissa. Korkealaatuisten ohutkalvojen hallittu kasvatus on yksi tärkeimmistä edellytyksistä n tyypin johdepolymeerien hyödyntämiselle orgaanisessa elektroniikassa. Tutkielman kokeellisessa osassa tutkittiin menetelmiä, joilla kahdesta tarkastellusta n tyypin johdepolymeeristä, poly(etyleenioksidi)lla funktionalisoidusta poly(bentsimidatso-bentsofenantroliini)sta (BBL–PEO) ja poly(atsoantrakinoni)sta, voitaisiin toistettavasti valmistaa korkealaatuisia ohutkalvoja. Valmistettujen ohutkalvojen laatua ja ominaisuuksia tutkittiin spektroskooppisin, mikroskooppisin ja sähkökemiallisin menetelmin. Lisäksi tutkittiin materiaalien valosähköisiä ominaisuuksia ja niiden soveltuvuutta aurinkoenergiaa hyödyntäviin sovelluksiin. Molemmista tutkituista johdepolymeereistä onnistuttiin valmistamaan ohutkalvoja, kun niille löydettiin sopivat liuottimet ja esikäsittelymenetelmät. Laadukkaimmat polymeeriohutkalvot valmistettiin spin–spray-pinnoitusmenetelmällä sekä dynaamisella spin coating -menetelmällä, joissa polymeeriliuosta sumutettiin (spin¬–spray) tai pipetoitiin (spin coating) pyörivän substraattilevyn pintaan. Näillä pinnoitus-menetelmillä pystyttiin hyvin hallitsemaan polymeeriohutkalvojen kasvatusta. BBL–PEO-ohutkalvot olivat tutkimusten perusteella selvästi laadukkaampia kuin poly(atsoantrakinoni)kalvot. BBL–PEO-kalvot olivat huomattavasti tasaisempia ja niiden valon absorbointikyky oli merkittävästi parempi. BBL–PEO näyttäisikin soveltuvan erinomaisesti korkealaatuisten ohutkalvojen valmistukseen. Valosähköisiä ominaisuuksia tutkittaessa havaittiin, että kohdistamalla valoa sähkökemiallisesti pelkistettyyn BBL–PEO-ohutkalvoon pystytään tuottamaan pieniä määriä sähkövirtaa. Vaikka tuotettujen virtojen suuruudet olivat hyvin pieniä, tulokset olivat lupaavia, kun huomioidaan valaisuun käytettyjen ledien pienet tehot. BBL–PEO-ohutkalvoja tulisi kuitenkin tutkia ja kehittää huomattavasti lisää, jotta niitä tulevaisuudessa voitaisiin hyödyntää orgaanisissa valosähköisissä sovelluksissa.

Chemical changes in biomass during torrefaction

Torrefaction is moderate thermal treatment (~200-300 °C) of biomass in an inert atmosphere. The torrefied fuel offers advantages to traditional biomass, such as higher heating value, reduced hydrophilic nature, increased its resistance to biological decay, and improved grindability. These factors could, for instance, lead to better handling and storage of biomass and increased use of biomass in pulverized combustors. In this work, we look at several aspects of changes in the biomass during torrefaction. We investigate the fate of carboxylic groups during torrefaction and its dependency to equilibrium moisture content. The changes in the wood components including carbohydrates, lignin, extractable materials and ashforming matters are also studied. And at last, the effect of K on torrefaction is investigated and then modeled. In biomass, carboxylic sites are partially responsible for its hydrophilic characteristic. These sites are degraded to varying extents during torrefaction. In this work, methylene blue sorption and potentiometric titration were applied to measure the concentration of carboxylic groups in torrefied spruce wood. The results from both methods were applicable and the values agreed well. A decrease in the equilibrium moisture content at different humidity was also measured for the torrefied wood samples, which is in good agreement with the decrease in carboxylic group contents. Thus, both methods offer a means of directly measuring the decomposition of carboxylic groups in biomass during torrefaction as a valuable parameter in evaluating the extent of torrefaction. This provides new information to the chemical changes occurring during torrefaction. The effect of torrefaction temperature on the chemistry of birch wood was investigated. The samples were from a pilot plant at Energy research Center of the Netherlands (ECN). And in that way they were representative of industrially produced samples. Sugar analysis was applied to analyze the hemicellulose and cellulose content during torrefaction. The results show a significant degradation of hemicellulose already at 240 °C, while cellulose degradation becomes significant above 270 °C torrefaction. Several methods including Klason lignin method, solid state NMR and Py-GC-MS analyses were applied to measure the changes in lignin during torrefaction. The changes in the ratio of phenyl, guaiacyl and syringyl units show that lignin degrades already at 240 °C to a small extent. To investigate the changes in the extractives from acetone extraction during torrefaction, gravimetric method, HP-SEC and GC-FID followed by GC-MS analysis were performed. The content of acetone-extractable material increases already at 240 °C torrefaction through the degradation of carbohydrate and lignin. The molecular weight of the acetone-extractable material decreases with increasing the torrefaction temperature. The formation of some valuable materials like syringaresinol or vanillin is also observed which is important from biorefinery perspective. To investigate the change in the chemical association of ash-forming elements in birch wood during torrefaction, chemical fractionation was performed on the original and torrefied birch samples. These results give a first understanding of the changes in the association of ashforming elements during torrefaction. The most significant changes can be seen in the distribution of calcium, magnesium and manganese, with some change in water solubility seen in potassium. These changes may in part be due to the destruction of carboxylic groups. In addition to some changes in water and acid solubility of phosphorous, a clear decrease in the concentration of both chlorine and sulfur was observed. This would be a significant additional benefit for the combustion of torrefied biomass. Another objective of this work is studying the impact of organically bound K, Na, Ca and Mn on mass loss of biomass during torrefaction. These elements were of interest because they have been shown to be catalytically active in solid fuels during pyrolysis and/or gasification. The biomasses were first acid washed to remove the ash-forming matters and then organic sites were doped with K, Na, Ca or Mn. The results show that K and Na bound to organic sites can significantly increase the mass loss during torrefaction. It is also seen that Mn bound to organic sites increases the mass loss and Ca addition does not influence the mass loss rate on torrefaction. This increase in mass loss during torrefaction with alkali addition is unlike what has been found in the case of pyrolysis where alkali addition resulted in a reduced mass loss. These results are important for the future operation of torrefaction plants, which will likely be designed to handle various biomasses with significantly different contents of K. The results imply that shorter retention times are possible for high K-containing biomasses. The mass loss of spruce wood with different content of K was modeled using a two-step reaction model based on four kinetic rate constants. The results show that it is possible to model the mass loss of spruce wood doped with different levels of K using the same activation energies but different pre-exponential factors for the rate constants. Three of the pre-exponential factors increased linearly with increasing K content, while one of the preexponential factors decreased with increasing K content. Therefore, a new torrefaction model was formulated using the hemicellulose and cellulose content and K content. The new torrefaction model was validated against the mass loss during the torrefaction of aspen, miscanthus, straw and bark. There is good agreement between the model and the experimental data for the other biomasses, except bark. For bark, the mass loss of acetone extractable material is also needed to be taken into account. The new model can describe the kinetics of mass loss during torrefaction of different types of biomass. This is important for considering fuel flexibility in torrefaction plants.

Teste de raios x na avaliação da qualidade de sementes de abóbora

As sementes de cucurbitáceas apresentam tegumento espesso, o que dificulta a visualização de sua morfologia interna. Para avaliar a eficiência da utilização do teste de raios X na detecção de danos internos e na avaliação da qualidade de sementes de abóbora, foram utilizados dez lotes de diferentes níveis de qualidade. As sementes foram submetidas às intensidades de 40, 45 e 50 kV por 20, 25 e 30 segundos em aparelho de raios X Faxitron HP modelo 43855A. Definidos a intensidade e o tempo de exposição que proporcionaram melhor visualização das estruturas internas das sementes, o teste de raios X foi realizado em quatro repetições de 100 sementes, por lote, para determinar a porcentagem de sementes vazias, cheias e translúcidas. Os sete lotes que apresentaram sementes das três categorias, em quantidade suficiente, foram submetidos ao teste de germinação para avaliação da influência da morfologia interna na qualidade fisiológica. Em uma segunda fase, as sementes dos outros três lotes foram divididas, sendo uma fração radiografada e outra não e ambas armazenados por um ano. O teste de raios X realizado na intensidade de 45 kV por 25 segundos é eficiente para identificar danos internos em sementes de abóbora, que afetam negativamente sua qualidade fisiológica. A exposição das sementes a essa radiação não afeta a sua qualidade fisiológica, avaliada mesmo após seu armazenamento pelo período de um ano.

Viologen based electroactive polymers and composites for durable electrochromic systems

Electrochromism, the phenomenon of reversible color change induced by a small electric charge, forms the basis for operation of several devices including mirrors, displays and smart windows. Although, the history of electrochromism dates back to the 19th century, only the last quarter of the 20th century has its considerable scientific and technological impact. The commercial applications of electrochromics (ECs) are rather limited, besides top selling EC anti-glare mirrors by Gentex Corporation and airplane windows by Boeing, which made a huge commercial success and exposed the potential of EC materials for future glass industry. It is evident from their patents that viologens (salts of 4,4ʹ-bipyridilium) were the major active EC component for most of these marketed devices, signifying the motivation of this thesis focusing on EC viologens. Among the family of electrochromes, viologens have been utilized in electrochromic devices (ECDs) for a while, due to its intensely colored radical cation formation induced by applying a small cathodic potential. Viologens can be synthesized as oligomer or in the polymeric form or as functionality to conjugated polymers. In this thesis, polyviologens (PVs) were synthesized starting from cyanopyridinium (CNP) based monomer precursors. Reductive coupling of cross-connected cyano groups yields viologen and polyviologen under successive electropolymerization using for example the cyclic voltammetry (CV) technique. For further development, a polyviologen-graphene composite system was fabricated, focusing at the stability of the PV electrochrome without sacrificing its excellent EC properties. High electrical conductivity, high surface area offered by graphene sheets together with its non-covalent interactions and synergism with PV significantly improved the electrochrome durability in the composite matrix. The work thereby continued in developing a CNP functionalized thiophene derivative and its copolymer for possible utilization of viologen in the copolymer blend. Furthermore, the viologen functionalized thiophene derivative was synthesized and electropolymerized in order to explore enhancement in the EC contrast and overall EC performance. The findings suggest that such electroactive viologen/polyviologen systems and their nanostructured composite films as well as viologen functionalized conjugated polymers, can be potentially applied as an active EC material in future ECDs aiming at durable device performances.

The infared optical properties of Sr2RuO4 and SmTiO3 including an object-oriented resistivity interface /

The perovskite crystal structure is host to many different materials from insulating to superconducting providing a diverse range of intrinsic character and complexity. A better fundamental description of these materials in terms of their electronic, optical and magnetic properties undoubtedly precedes an effective realization of their application potential. SmTiOa, a distorted perovskite has a strongly localized electronic structure and undergoes an antiferromagnetic transition at 50 K in its nominally stoichiometric form. Sr2Ru04 is a layered perovskite superconductor (ie. Tc % 1 K) bearing the same structure as the high-tem|>erature superconductor La2_xSrrCu04. Polarized reflectance measurements were carried out on both of these materials revealing several interesting features in the far-infrared range of the spectrum. In the case of SmTiOa, although insulating, evidence indicates the presence of a finite background optical conductivity. As the temperature is lowered through the ordering temperature a resonance feature appears to narrow and strengthen near 120 cm~^ A nearby phonon mode appears to also couple to this magnetic transition as revealed by a growing asymmetry in the optica] conductivity. Experiments on a doped sample with a greater itinerant character and lower Neel temperature = 40 K also indicate the presence of this strongly temperature dependent mode even at twice the ordering temperature. Although the mode appears to be sensitive to the magnetic transition it is unclear whether a magnon assignment is appropriate. At very least, evidence suggests an interesting interaction between magnetic and electronic excitations. Although Sr2Ru04 is highly anisotropic it is metallic in three-dimensions at low temperatures and reveals its coherent transport in an inter-plane Drude-like component to the highest temperatures measured (ie. 90 K). An extended Drude analysis is used to probe the frequency dependent scattering character revealing a peak in both the mass enhancement and scattering rate near 80 cm~* and 100 cm~* respectively. All of these experimental observations appear relatively consistent with a Fermi-liquid picture of charge transport. To supplement the optical measurements a resistivity station was set up with an event driven object oriented user interface. The program controls a Keithley Current Source, HP Nano-Voltmeter and Switching Unit as well as a LakeShore Temperature Controller in order to obtain a plot of the Resistivity as a function of temperature. The system allows for resistivity measurements ranging from 4 K to 290 K using an external probe or between 0.4 K to 295 K using a Helium - 3 Cryostat. Several materials of known resistivity have confirmed the system to be robust and capable of measuring metallic samples distinguishing features of several fiQ-cm.

Carbohydrate refeeding rapidly reverses the adaptive upregulation of human skeletal muscle pyruvate dehydrogenase kinase following a high fat diet

The time course for the reversal of the adaptive increase in pyruvate dehydrogenase kinase (PDK) activity following a 6d high fat diet (HP: 4.2 ± 0.2 % carbohydrate; 75.6 ± 0.4 % fat; 19.5 ± 0.8 % protein) was investigated in human skeletal muscle (vastus lateralis). HF feeding increased PDK activity by 44% (from 0.081 ± 0.025 min"' to 0.247 ± 0.025 mm\p < 0.05). Following carbohydrate re-feeding, (88% carbohydrate; 5% fat; 7% protein), PDK activity had returned to baseline (0.111 ± 0.014 min"') within 3h of re-feeding. The active fraction of pyruvate dehydrognease (PDHa) was depressed following 6d of the HF diet (from 0.89 ± 0.21 mmol/min/kg WW to 0.32 ± 0.05 mmol/min/kg ww,p <0.05) and increased to pre-HF levels by 45 min of post re-feeding (0.74 ±0.19 mmol/min/kg ww) and remained elevated for 3h. Western blotting analysis of the PDK isoforms, PDK4 and PDK2, revealed a 31% increase in PDK4 protein content following the HF diet, with no change in PDK2 protein. This adaptive increase in PDK4 protein content was reversed with carbohydrate re-feeding. It was concluded that the adaptive up-regulation in PDK activity and PDK4 protein content was fiilly reversed by 3h following carbohydrate re-feeding.

Modulation of Oxytocin Receptors in Right Ventricular Hypertrophy

L’hypertension pulmonaire (HP) est une maladie dont l’étiologie est inconnue et qui entraîne ultimement une défaillance du ventricule droit (VD) et le décès. L’HP peut être induite chez le rat par la la monocrotaline (MCT), un alcaloïde pyrrolizidique extrait de la plante Crotalaria Spectabilis, causant des lésions à l’endothélium des artères pulmonaires, menant à un épaississement de ces dernières et à une augmentation de la résistance vasculaire. Ceci à pour conséquence de causer une hypertrophie du VD, de l’inflammation, une dysfonction endothéliale NO-dépendante des artères coronariennes et une augmentation des peptides natriurétiques circulants. Objectif: Nous avons testé l’hypothèse selon laquelle l’étiopathologie de l’HP impliquerait le récepteur à ocytocine (OTR) dû à son implication fonctionnelle avec les cytokines inflammatoires et la libération du peptide natriurétique atrial (ANP) et du NO. Méthodes: Des rats mâles Sprague-Dawley pesant 220-250g reçurent une seule injection sous-cutanée de MCT (60 mg/kg). 6 à 7 semaines (46±1 jours) suivant l’injection, les rats furent sacrifiés et l’expression génique et protéique fut déterminée par PCR en temps réel et par western blot, respectivement, dans le VD et le ventricule gauche (VG) Résultats: Les rats traités au MCT démontrèrent une augmentation significative du VD. Une hypertrophie du VD était évidente puisque le ratio du VD sur le VG ainsi que le poids du septum étaient près de 77% plus élevés chez les rats traités au MCT que chez les rats contrôles. Le traitement au MCT augmenta l’expression génique d’ANP (3.7-fois dans le VG et 8-fois dans le VD) ainisi que le NP du cerveau (2.7-fois dans le VG et 10-fois dans le VD). Les transcrits de trois récepteurs de NP augmentèrent significativement (0.3-2 fois) seulement dans le VD. L’expression protéique de la NO synthase (iNOS) fut également augmentée de façon sélective dans le VD. Par contre, les transcripts de NOS endothéliale et de NOS neuronale étaient plus élevés (0.5-2 fold) dans le VG. L’ARNm et l’expression protéique d’OTR furent diminués de 50% dans le VD, tandis qu’une augmentation de l’expression des cytokines IL-1β and IL-6 fut observée. L’ARNm de Nab1, un marqueur d’hypertrophie pathologique, fut augmentée de deux-fois dans le VD. Conclusion: L’augmentation d’expression génique de NP dans le VD des rats traités au MCT est associée à une augmentation des transcripts du récepteur NP, suggérant une action locale de NP dans le VD durant l’HP. L’expression d’OTR est atténuée dans le VD, possiblement par des cytokines inflammatoires puisque le promoteur du gène de l’OTR contient de multiples éléments de réponse aux interleukines. Diminuer l’expression d’OTR dans le VD durant l’hypertension pulmonaire pourrait influencer de manière positive la fonction cardiaque car l’OTR régule la contractilité et le rythme cardiaque. Mots clés: hypertension pulmonaire, hypertrophie du ventricule droit monocrotaline, récepteur à ocytocine, inflammation, peptides natriurétiques.

Problèmes de perception de la parole dans le bruit chez les enfants présentant un trouble de traitement auditif

Il est bien connu que les enfants qui présentent un trouble de traitement auditif (TTA) ont de la difficulté à percevoir la parole en présence de bruit de fond. Cependant, il n’existe aucun consensus quant à l’origine de ces difficultés d’écoute. Ce programme de recherche est consacré à l’étude des incapacités sous-jacentes aux problèmes de perception de la parole dans le bruit chez les enfants présentant un TTA. Le Test de Phrases dans le Bruit (TPB) a été développé afin d’examiner si les difficultés de perception de la parole dans le bruit d’enfants ayant un TTA relèvent d’incapacités auditives, d’incapacités cognitivo-linguistiques ou des deux à la fois. Il comprend cinq listes de 40 phrases, composées de 20 phrases hautement prévisibles (HP) et de 20 phrases faiblement prévisibles (FP), de même qu’un bruit de verbiage. Le niveau de connaissance du mot clé (mot final) de chaque phrase a été vérifié auprès d’un groupe d’enfants âgés entre 5 et 7 ans. De plus, le degré d’intelligibilité des phrases dans le bruit et le niveau de prévisibilité ont été mesurées auprès d’adultes pour assurer l’équivalence entre les listes. Enfin, le TPB a été testé auprès d’un groupe de 15 adultes et d’un groupe de 69 enfants sans trouble auditif avant de l’administrer à des enfants ayant un TTA. Pour répondre à l’objectif général du programme de recherche, dix enfants présentant un TTA (groupe TTA) et dix enfants jumelés selon le genre et l’âge sans difficulté auditive (groupe témoin) ont été soumis aux listes de phrases du TPB selon différentes conditions sonores. Le groupe TTA a obtenu des performances significativement plus faibles comparativement au groupe témoin à la tâche de reconnaissance du mot final des phrases présentées en même temps qu’un bruit de verbiage compétitif, aux rapports signal-sur-bruit de 0, +3 et +4 dB. La moyenne de la différence des scores obtenue entre les phrases HP et FP à chaque condition expérimentale de bruit était similaire entre les deux groupes. Ces résultats suggèrent que les enfants ayant un TTA ne se distinguent pas des enfants du groupe témoin au plan de la compétence cognitivo-linguistique. L’origine des difficultés d’écoute de la parole dans le bruit dans le cas de TTA serait de nature auditive. Toutefois, les résultats des analyses de groupe diffèrent de ceux des analyses individuelles. Les divers profils de difficultés d’écoute identifiés auprès de cette cohorte appuient l’importance de continuer les investigations afin de mieux comprendre l’origine des problèmes de perception de la parole dans le bruit dans le cas de TTA. En connaissant mieux la nature de ces difficultés, il sera possible d’identifier les stratégies d’intervention de réadaptation spécifiques et efficaces.

Impact de la maladie du greffon contre l’hôte sur la reconstitution immunitaire suite à une greffe de moelle osseuse allogénique

La transplantation allogénique de cellules souches hématopoïétiques est une technique très efficace pour traiter différents cancers du sang. Malheureusement la réaction du greffon contre l’hôte (GVHD) demeure la cause principale de morbidité et de mortalité post-greffe. La GVHD entraîne une diminution de la reconstitution immunitaire ce qui accentue considérablement l’immunosuppression associée à ce traitement et de ce fait augmente les risques d’infection et de rechute. Notre laboratoire a démontré précédemment que les niveaux élevés d’IL-7 dans des hôtes lymphopéniques interféraient avec la capacité des cellules dendritiques (DC) à soutenir la prolifération homéostatique (PH) des lymphocytes T CD4+. Puisque les niveaux d’IL-7 sont aussi élevés dans un contexte de GVHD, nous avons émis l’hypothèse que la signalisation de l’IL-7 sur les DC pouvait contribuer à diminuer la reconstitution immunitaire des lymphocytes T CD4+. Pour répondre à cette question, nous avons utilisé le modèle murin de GVHD C57BL/6 (B6) dans B6D2F1. Afin de régénérer une niche hématopoïétique permissive à la PH des lymphocytes T CD4+, nous avons transplanté des souris B6D2F1 avec de la moelle osseuse de souris B6 IL-7Rα-/-. La GVHD a été induite en transférant des lymphocytes T B6 réactifs aux cellules B6D2F1. Dans les souris contrôles, la PH des lymphocytes T CD4+ est maintenue. Par contre, la PH est absente dans les souris en GVHD malgré la présence d’une niche périphérique qui ne répond pas à l’IL-7. L’absence de PH des lymphocytes T CD4+ durant la GVHD est associée à une diminution du nombre de DC. En utilisant un test de cytotoxicité in vivo nous démontrons que les DC B6 générées dans une hôte B6D2F1 sont éliminées par les lymphocytes T B6 alloréactifs. En conclusion, nos résultats démontrent que l’immunosuppression associée à la GVHD est en partie causée par une élimination des DC par les lymphocytes T allogéniques. Nous postulons donc que la perte des DC, et non la signalisation de l’IL-7 sur les DC, est le facteur limitant la PH des lymphocytes T CD4+ durant la GVHD.