3D culture of postnatal retinal stem cells using self assembling polymers

PURPOSE We have previously shown that retinal stem cells (RSCs) can be isolated from the radial glia population of the newborn mouse retina (Angénieux et al., 2006). These RSCs have a great capacity to renew and to generate a large number of neurons including cells differentiated towards the photoreceptor lineage (Mehri-Soussi et al., 2006). However, recent published results from our lab revealed that such cells have a poor integration and survival rate after grafting. The uncontrolled environment of a retina seems to prevent good integration and survival after grafting in vivo. To bypass this problem, we are evaluating the possibility of generating in vitro a hemi-retinal tissue before transplantation. METHODS RSC were expanded and cells passaged <10 were seeded in a solution containing poly-ethylene-glycol (PEG) polymer based hydrogels crosslinked with peptides that are chosen to be substrates for matrix metalloproteinases. Various doses of cross linkers peptides allowing connections between PEG polymers were tested. Different growth factors were studied to stimulate cell proliferation and differentiation. RESULTS Cells survived only in the presence of EGF and FGF-2 and generated colonies with a sphere shape. No cells migrated within the gel. To improve the migration and the repartition of the cells in the gels, the integrin ligand RGDSP was added into the gel. In the presence of FGF-2 and EGF, newly formed cell clusters appeared by cell proliferation within several days, but again no outspreading of cells was observed. No difference was even seen when the stiffness of the hydrogels or the concentration of the integrin ligand RGDSP were changed. However, our preliminary results show that RSCs still form spheres when laminin is entrapped in the gel, but they started to spread out having a neuronal morphology after around 2 weeks. The neuronal population was assessed by the presence of the neuronal marker b-tubulin-III. This differentiation was achieved after successive steps of stimulations including FGF-2 and EGF, and then only FGF-2. Glial cells were also present. Further characterizations are under process. CONCLUSIONS RSC can be grown in 3D. Preliminary results show that neuronal cell phenotype acquisition can be instructed by exogenous stimulations and factors linked to the gel. Further developments are necessary to form a homogenous tissue containing retinal cells.

Transjugular liver biopsy: prospective evaluation of the angle formed between the hepatic veins and the vena cava main axis and modification of a semi-automated biopsy device in cases of an unfavorable angle.

In cases of transjugular liver biopsies, the venous angle formed between the chosen hepatic vein and the vena cava main axis in a frontal plane can be large, leading to technical difficulties. In a prospective study including 139 consecutive patients who underwent transjugular liver biopsy using the Quick-Core biopsy set, the mean venous angle was equal to 49.6 degrees. For 21.1% of the patients, two attempts at hepatic venous catheterization failed because the venous angle was too large, with a mean of 69.7 degrees. In all of these patients, manual reshaping of the distal curvature of the stiffening metallic cannula, by forming a new mean angle equal to 48 degrees , allowed successful completion of the procedure in less than 10 min.

Modelling of crowded polymers elucidate effects of double-strand breaks in topological domains of bacterial chromosomes.

Using numerical simulations of pairs of long polymeric chains confined in microscopic cylinders, we investigate consequences of double-strand DNA breaks occurring in independent topological domains, such as these constituting bacterial chromosomes. Our simulations show a transition between segregated and mixed state upon linearization of one of the modelled topological domains. Our results explain how chromosomal organization into topological domains can fulfil two opposite conditions: (i) effectively repulse various loops from each other thus promoting chromosome separation and (ii) permit local DNA intermingling when one or more loops are broken and need to be repaired in a process that requires homology search between broken ends and their homologous sequences in closely positioned sister chromatid.

A novel semi-fragile forensic watermarking scheme for remote sensing images

Peer-reviewed

Spatial filtering for pilot-aided WCDMA systems: a semi-blind subspace approach

This paper proposes a spatial filtering technique forthe reception of pilot-aided multirate multicode direct-sequencecode division multiple access (DS/CDMA) systems such as widebandCDMA (WCDMA). These systems introduce a code-multiplexedpilot sequence that can be used for the estimation of thefilter weights, but the presence of the traffic signal (transmittedat the same time as the pilot sequence) corrupts that estimationand degrades the performance of the filter significantly. This iscaused by the fact that although the traffic and pilot signals areusually designed to be orthogonal, the frequency selectivity of thechannel degrades this orthogonality at hte receiving end. Here,we propose a semi-blind technique that eliminates the self-noisecaused by the code-multiplexing of the pilot. We derive analyticallythe asymptotic performance of both the training-only andthe semi-blind techniques and compare them with the actual simulatedperformance. It is shown, both analytically and via simulation,that high gains can be achieved with respect to training-onlybasedtechniques.

Drosophila rely on learning while foraging under semi-natural conditions

Learning is predicted to affect manifold ecological and evolutionary processes, but the extent to which animals rely on learning in nature remains poorly known, especially for short-lived non-social invertebrates. This is in particular the case for Drosophila, a favourite laboratory system to study molecular mechanisms of learning. Here we tested whether Drosophila melanogaster use learned information to choose food while free-flying in a large greenhouse emulating the natural environment. In a series of experiments flies were first given an opportunity to learn which of two food odours was associated with good versus unpalatable taste; subsequently, their preference for the two odours was assessed with olfactory traps set up in the greenhouse. Flies that had experienced palatable apple-flavoured food and unpalatable orange-flavoured food were more likely to be attracted to the odour of apple than flies with the opposite experience. This was true both when the flies first learned in the laboratory and were then released and recaptured in the greenhouse, and when the learning occurred under free-flying conditions in the greenhouse. Furthermore, flies retained the memory of their experience while exploring the greenhouse overnight in the absence of focal odours, pointing to the involvement of consolidated memory. These results support the notion that even small, short lived insects which are not central-place foragers make use of learned cues in their natural environments.

Feijão guandu cru na alimentação de frangos caipiras criados em sistema semi-intensivo

O objetivo deste trabalho foi avaliar os efeitos da substituição do farelo de soja pelo feijão guandu cru na alimentação de frangos caipiras criados em sistema semi-intensivo. Foram utilizados 525 frangos de corte da linhagem Caipira Pesadão, com idade inicial de 35 dias, distribuídos em cinco tratamentos com cinco repetições de 21 aves cada um. Os tratamentos consistiram na substituição de 0, 5, 10, 15 e 20% do farelo de soja pelo feijão guandu cru moído. Foram avaliados o ganho de peso, o consumo de ração, a conversão alimentar, o rendimento de carcaça e de cortes, o peso do pâncreas e a qualidade da carne. A substituição do farelo de soja pelo feijão guandu em até 15,45%, nas dietas de frangos caipiras de corte, com idade de 57 a 71 dias, não altera o ganho de peso. O aumento dos níveis de feijão guandu na ração não afeta o rendimento de carcaça, o peso do pâncreas e os parâmetros de qualidade da carne.

RELAÇÕES HÍDRICAS INTERNAS DO UMBUZEIRO SOB CONDIÇÕES SEMI-ÁRIDAS

Realizou-se um estudo na Embrapa-Centro de Pesquisa Agropecuária do Trópico Semi-Árido (CPATSA), Petrolina-PE, objetivando identificar os mecanismos, através dos quais o umbuzeiro (Spondias tuberosa Arr. Cam.) mantém o balanço hídrico interno durante as estações de seca e chuvosa. Os resultados obtidos basearam-se em observações do potencial hídrico e de seus componentes, utilizando-se da câmara de pressão e câmaras higrométricas / microvoltímetro. Sob condições de seca, os valores mais baixos de potencial hídrico e potencial osmótico foram observados em torno das 8 h, atingindo, respectivamente --0,97 MPa e --1,17 MPa, resultando em uma pressão de turgor de 0,2 MPa. A pressão mais baixa ocorreu às 16 h, atingindo 0,16 MPa. Entretanto, a recuperação hídrica não foi observada, até o final dia. Durante a estação chuvosa, os valores de mais baixos de potencial hídrico foram obtidos às 14 h , quando foram detectados, respectivamente --1,55 MPa. Neste momento, o potencial osmótico atingiu --1,57 MPa , culminando com uma pressão de turgor de 0,02 MPa. Entretanto, até o final do dia, a condição hídrica da planta foi similar à observada no início do dia. Estes resultados sugerem que o umbuzeiro apresenta duas estratégias para manter, durante o dia, um balanço hídrico interno favorável, dentro das condições ambientais estudadas. Sob condições de sequeiro, o balanço seria mantido através da utilização da água armazenada nas túberas e uma baixa transpiração. Durante a estação das chuvas, o balanço hídrico pode ter sido mediado por um ajuste osmótico, a julgar pelas variações observadas à tarde entre níveis de potencial hídrico e potencial osmótico.

The power of support: an exploration of the mentoring relationship

Tutkimuksen pääasiallisena tavoitteena on selvittää ne moninaiset näkökulmat, joita mentori sekä mentoroitava läpikäyvät osallistuessaan mentorointiohjelmaan. Tutkimuksen avulla pyritään myös selvittämään vastaavanlaisen tuen saannin tehokkuutta sekä mentoroinnin sisältäminen elementtien hyödyllisyyttä. Pyrkimyksenä on myös selvittää sekä ymmärtää ne dynaamiset mentorointiprosessin ominaisuudet molempien prosessiin osallistuvien tahojen näkökulmasta. Tutkimuksen teoriaosuudessa käsitellään mentorointia, mentorointiin liittyviä vuorovaikutussuhteita sekä näihin liittyviä eri näkökulmia. Teoria koostuu monipuolisesta, kansainvälisestä sekä kotimaisesta kirjallisuudesta. Tutkimuksen aineiston keruu suoritetaan puolistrukturoiduilla avoimilla haastatteluilla, jotka suoritetaan järjestämällä kahdenkeskisiä teemahaastatteluita. Mentorointisuhteella on todettu olevan voimakas vaikutus siihen osallistuvien henkilöiden elämään. Mentorointisuhteen tarkoituksellisuus on tullut todettua myös kun itse vuorovaikutussuhde on osoittautunut hyödylliseksi osallistujille. Mentoroitavilla on odotuksia, että mentorit täyttävät seuraavanlaisia rooleja: neuvonantaja, roolimalli sekä mahdollisesti tukea antava ystävä. Kaikissa läpikäydyissä tapauksissa mentori pystyi tarjoamaan jonkun näistärooleista mentoroitavalle. Mentoroitava, puolestaan, otti tämän tuen vastaan jahyötyi siitä.

Asiakaspalveluprosessin mittariston luominen: Case Borealis Polymers Oy

Työn tavoitteena oli luoda asiakaspalveluprosessin mittaristo päivittäisen operatiivisen toiminnan seuraamiseksi ja parantamiseksi. Tarkoituksena oli mitata tilaustoimitusketjun suorituskykyä sekä tutkia mahdollisia kehitys ja parannuskohteita. Työ tehtiin Borealis Polymers Oy:n Fenolin Liiketoimintayksikölle. Yhtiön käytössä on Balanced Scorecard KPI- mittaristo. Asiakaspalveluprosessin mittaristo luotiin BSC asiakasnäkökulman mukaisesti soveltuen yhtiön toimintaympäristöön ja tavoitteisiin. Mittariston tarkoituksena on täydentää KPI- mittareita keskittyen päivittäisen asiakaspalveluprosessin suorituskyvyn ja asiakastyytyväisyyden parantamiseen. Asiakaspalveluprosessia kuvaavia mittareita testattiin suorittamalla asiakastyytyväisyyskysely, joka käytännössä toteutettiin sähköpostitse tehtynä tyytyväisyysmittauksena. Mittauksella haluttiin selvittää asiakastyytyväisyyden taso, palvelun eritekijöiden suhteellinen tärkeys asiakkaille eli mitkä laadun tekijät ovat asiakkaille tärkeimmät sekä miten asiakas kokee Borealiksen asiakaspalvelun suhteessa kilpailijoihin. Asiakaspalvelukysely on osa yhtiön kuluen vuoden aikana tehtävää asiakastyytyväisyysselvitystä. Lisäksi työn tavoitteena oli luoda jatkuvan toiminnan seuraamiseksi tulevaisuutta varten mittarit asiakkaille tärkeimpien laadun tekijöiden seuraamiseksi.

Estudi de les estratègies comportamentals dels gripau corredor (Bufo Calamita) a la zona semi-àrida de Mas de Melons (terme municipal de Lleida) durant l'hivern i principis de primavera del 2007

En aquest treball s’han radiomarcat, un total de 4 gripaus corredors (Bufo calamita) que posteriorment foren alliberats a la Bassa de l’Astor, per tal d’estudiar les estratègies comportamentals de l’espècie en una zona semi-àrida. Dels 4 animals alliberats, un es perdé als pocs dies, la resta foren seguits mitjançant radioseguiment uns 64 dies, entre finals d’hivern i principis de primavera del 2007. En el treball de seguiment s’anotà en cada una de les localitzacions la temperatura ambiental del moment i la freqüència a la qual emetia l’emissor. Donat que es tenien els emissors calibrats, a partir d’aquesta freqüència es podia obtenir la temperatura a la qual es trobava l’emissor, és a dir la temperatura corporal del gripau en aquest cas. Mitjançant programes estadístics s’ha pogut determinar que durant el període hivernal i principis de primavera existeix una relació estadísticament significativa entre la variació de la temperatura ambiental i la temperatura corporal dels gripaus. Aquesta relació no es dona però en el període estival. Això fa pensar que el comportament del calamita esdevé una forma de termoregulació actuant per tal d’evitar extrems crítics de temperatura i humitat. S’ha pogut determinar també que gràcies a les característiques dels refugis utilitzats en la zona d’estudi (munts de pedres o caus d’altres espècies) els gripaus aconsegueixen mantenir-se en ambients on la variació de temperatura és inferior a la variació de la temperatura exterior. Així la variació de la temperatura corporal dels gripaus és també inferior. Pel que fa als moviments entre els diferents refugis, aquests han variat en funció de cada animal. La distància mitja recorreguda en el total dels desplaçaments ha estat d’uns 185 metres lineals. Aquests desplaçaments s’han donat sempre en dies de pluja o l’endemà d’un dia de pluja.

Gas exchange of the umbu tree under semi-arid conditions

A study was carried out at Embrapa Semi-Árido, Petrolina-PE, Brazil, aiming to understand the gas exchange process of the umbu tree (Spondias tuberosa Arr. Cam.) in the dry and rainy seasons. Stomatal conductance, transpiration, photosynthesis and internal CO2 concentration were obtained with a portable infrared gas analyzer (IRGA). During the dry season the umbu tree showed a much lower stomatal conductance early in the morning, as soon as the vapor pressure deficit increased, apparently affecting CO2 assimilation more than transpiration. The highest values were detected around 6:00 am but decreased to the lowest points between 10:00 am and 2:00 pm. During the rainy season, however, stomatal conductance, transpiration and photosynthesis were significantly higher, reaching the highest values between 8:00 and 10:00 am and the lowest around 2:00 pm. It was also observed at 4:00 pm, mainly during the rainy season, an increase on these variables indicating that the umbu tree exhibits a two-picked daily course of gas exchange.