Insulin-like growth factor I (IGF-I) and liver cirrhosis

Insulin-like growth factor I (IGF-I) is a polypeptide hormone secreted by multiple tissues in response to growth hormone (GH). It is partly responsible for GH activity, and also has glucose-lowering and anabolizing effects. Ninety percent of circulating IGF-I originates in the liver and has autocrine, paracrine, and endocrine effects, the latter on multiple tissues. Liver cirrhosis results in a progressive decline of hepatic IGF-I output, and this factor may become undetectable in advanced disease. Some cirrhosis complications, mainly those nutritional and metabolic in nature (insuline resistance, malnutrition, osteopenia, hypogonadism, intestinal disorders), may be at least partly related to this IGF-I deficiency, since some IGF-I effects represent a reverse image of cirrhosis complications. Despite this, IGF-I replacement therapy has been never suggested for cirrhosis. A number of experimental studies in cirrhotic rats showed that therapy using low-dose recombinant IGF-I exerts two types of effect on experimental cirrhosis: a) liver improvement driven by improved hepatocellular function, portal hypertension, and liver fibrosis; and b) cirrhosis-related extrahepatic disorder improvement driven by improved food efficiency, muscle mass, bone mass, gonadal function and structure, and intestinal function and structure, with a normalization of sugar and amino acid malabsorption, and improved intstinal barrier function, manifested by reduced endotoxemia and bacterial translocation. Subsequently, the first randomized, double-blind, placebo-controlled, pilot clinical trial in a small number of cirrhotic patients showed increased serum albumin and improved energy metabolism as a result of IGF-I use. Further clinical trials are needed to identify adequate IGF-I doses, administration duration and frequency, and the subgroup of cirrhotic patients who will benefit most from this replacement therapy

Evaluation of the nutritional aspects and cholesterol oxidation products of pork liver and fish patés

A comparative study between traditional patés elaborated with pork liver and fish patés (salmon, anchovy and cod) was carried out. The nutritional value and their security related to cholesterol oxidation products (COP) content were evaluated. Salmon paté showed similar fat content (24-28%) and energetic value (300Kcal/100g) to pork liver patés, whereas patés made with anchovy and cod showed less fat (13-16%) and calories (200-236 Kcal/100g). PUFA/SFA ratios were much higher in all fish patés (1.55-4.95) than in liver pork patés (0.36-0.44). No great differences were found in ω-6/ω-3 ratio between salmon and pork liver patés (11.34-18.4), being even much higher this ratio in anchovy (32.32) and cod patés (62.77). EPA and DHA supply was around 0.63 for salmon, 0.21 for anchovy and 0.07 for cod patés. Cholesterol amounts were lower in fish patés (31-37mg/100g) than in pork liver patés (77-102mg/100g). Total COP ranged 0.38-2.83ppm, without clear differences between pork liver and fish patés

LISA and LISA PathFinder, the endeavour to detect low frequency GWs

This is a review about LISA and its technology demonstrator, LISA PathFinder. We first describe the conceptual problems which need to be overcome in order to set up a working interferometric detector of low frequency Gravitational Waves (GW), then summarise the solutions to them as currently conceived by the LISA mission team. This will show that some of these solutions require new technological abilities which are still under development, and which need proper test before being fully implemented. LISA PathFinder (LPF) is the the testbed for such technologies. The final part of the paper will address the ideas and concepts behind the PathFinder as well as their impact on LISA.Comment: 25 pages, 21 figures, presented at the Spanish Relativity Meeting, Mallorca September 2006. Will be published in Journal of Physics: Conference Series, IOP. To be published in Journal of Physics: Conference Series, IO

Prediction of peptide and protein propensity for amyloid formation

Understanding which peptides and proteins have the potential to undergo amyloid formation and what driving forces are responsible for amyloid-like fiber formation and stabilization remains limited. This is mainly because proteins that can undergo structural changes, which lead to amyloid formation, are quite diverse and share no obvious sequence or structural homology, despite the structural similarity found in the fibrils. To address these issues, a novel approach based on recursive feature selection and feed-forward neural networks was undertaken to identify key features highly correlated with the self-assembly problem. This approach allowed the identification of seven physicochemical and biochemical properties of the amino acids highly associated with the self-assembly of peptides and proteins into amyloid-like fibrils (normalized frequency of β-sheet, normalized frequency of β-sheet from LG, weights for β-sheet at the window position of 1, isoelectric point, atom-based hydrophobic moment, helix termination parameter at position j+1 and ΔGº values for peptides extrapolated in 0 M urea). Moreover, these features enabled the development of a new predictor (available at http://cran.r-project.org/web/packages/appnn/index.html) capable of accurately and reliably predicting the amyloidogenic propensity from the polypeptide sequence alone with a prediction accuracy of 84.9 % against an external validation dataset of sequences with experimental in vitro, evidence of amyloid formation

Antioxidant status and glutathione metabolism in peripheral blood mononuclear cells from patients with chronic hepatitis C

BACKGROUND/AIMS: Oxidative stress could play a role in the pathogenesis of hepatitis C virus infection. We investigated the oxidant/antioxidant status in peripheral blood mononuclear cells from patients with chronic hepatitis C and controls. METHODS/RESULTS: Lipid peroxidation products and superoxide dismutase activity in peripheral blood mononuclear cells were higher in chronic hepatitis C patients than in healthy subjects while glutathione S-transferase activity was reduced in patients as compared to controls. Catalase, glutathione peroxidase and glutathione reductase were similar in chronic hepatitis C and normal individuals. No statistically significant differences were found between patients and controls with regard to glutathione levels in peripheral blood mononuclear cells, but 35% of patients with chronic hepatitis C showed values of glutathione and oxidized glutathione which were below and above, respectively, the limits of normal controls. Finally, the glutathione synthetic capacity of the cytosol of peripheral blood mononuclear cells was significantly higher in patients than in controls, indicating increased glutathione turnover in lymphocytes from patients with chronic hepatitis C. CONCLUSIONS: Oxidative stress is observed in peripheral blood mononuclear cells from chronic hepatitis C patients. This process might alter lymphocyte function and facilitate the chronicity of the infection

From laboratory experiments to LISA Pathfinder: achieving LISA geodesic motion

International audienceThis paper presents a quantitative assessment of the performance of the upcoming LISA Pathfinder geodesic explorer mission. The findings are based on the results of extensive ground testing and simulation campaigns using flight hardware and flight control and operations algorithms. The results show that, for the central experiment of measuring the stray differential acceleration between the LISA test masses, LISA Pathfinder will be able to verify the overall acceleration noise to within a factor two of the LISA requirement at 1 mHz and within a factor 10 at 0.1 mHz. We also discuss the key elements of the physical model of disturbances, coming from LISA Pathfinder and ground measurement, that will guarantee the LISA performance

Assessment of oesophageal emptying in achalasia patients by intraluminal impedance monitoring

Oesophageal emptying can be assessed by radiographic and scintigraphic tests with radiation exposure or by multichannel intraluminal impedance monitoring (MII). The aim of this study was to evaluate the applicability of MII for the assessment of oesophageal emptying in achalasia patients. In 10 achalasia patients, impedance tracings were scored independently by three observers after ingestion of a 100-mL barium bolus. Bolus clearance time (BCT) and height of barium column were scored using fluoroscopic images acquired at 20-s intervals. All patients showed a low baseline impedance level in the distal oesophagus. Air trapping in the proximal oesophagus was detected in nine patients. BCT on MII was similar to that on fluoroscopy in 40-70% of the patients. Correlations between height of barium on fluoroscopy and fluid level on MII were poor to moderate at different time intervals. Concordance (Kendall's coefficient) between the three observers for assessment of fluid level on MII was 0.31 (P = 0.04) at 1 and 5 min, 0.26 (P = 0.08) at 10 and 0.44 (P = 0.01) at 15 min. We conclude that in achalasia patients, low baseline impedance levels and air entrapment in the proximal oesophagus limit the value of intraluminal impedance monitoring as a test of oesophageal emptying

La psicofísica de la velocidad en el contexto de la conducción real de automóviles

Performance in real traffic environments. Previous studies on speed estimation in traffic have been performed in very different scenarios, varying from the complexity of real traffic situations to the simpler and more controlled simulated conditions. The aim of this research was to compare the performance in real traffic environments (road and highway) with a closed track used in some recent experimental studies (Recarte and Nunes, 1996), and to analyze the effect of sex and driving experience on speed estimation. Thirty-six participants (18 male and 18 female, half of each group being dr ivers and half non-drivers) estimated the speed of the car in which they traveled as passengers. The actual speed values varied in the range of 40 to 100 kph. for road, and 70 to 120 kph. for the highway condition. Linear, logarithmic and power functions ha ve been fitted, but linear fit was the best in most cases. Accounted variances by linear fit were: r2 = . 86 and r2= . 81, for closed track and open road, respectively; r2 = . 87 and r2= . 83, for drivers and non-drivers, respectively; and r 2= . 85, for both sexes. Results obtained on the closed track by Recarte and Nunes (1996) were replicated in the same condition and also verified for the conventional road scenario. However, a different pattern of errors was found on the highway. From the viewpoint of psychophysics, the participants were more accurate on the closed track than in real traffic conditions considered as a whole. The differences found between road and highway and the effects of the participant variables are discussed.En la investigación presente se ha estudiado la psicofísica de la velocidad en un contexto de conducción real de vehículos, teniendo en cuenta si los sujetos tenían o no experiencia como conductores, y si la conducción se realizaba en un escenario natural con tráfico o en un circuito sin tráfico, con el objeto de comparar los resultados con los de otra investigación reciente (Recarte and Nunes, 1996). Treinta y seis sujetos, divididos en cuatro grupos por sexo y experiencia de nueve sujetos cada uno, estimaron la velocidad de un coche en el que viajaban como acompañantes del conductor en dos escenarios: un circuito cerrado con ausencia de tráfico y una carretera/autovía con una densidad media de tráfico. El rango de velocidades utilizadas fue de 40 a 140 Km./h. en el circuito y de 40 a 120 Km./h. en la carretera/autovía. Se han ajustado tres funciones: lineal, logarítmica y potencial. El valor de r2 de los tres ajustes es muy similar en todos casos, pero generalmente mayor para la función linea. Considerando el escenario el ajuste lineal en el circuito fue mayor que en la autovía/carretera, r2= 0,86 y r2 =0,81, respectivamente. También el ajuste lineal para el grupo de los sujetos con experiencia de conducir es mejor que en el de no conductores, r2= 0,87 y r2=0,83, respectivamente. En cambio, no se observa diferencia alguna entre los varones y las mujeres, r2= 0,85 para los dos grupos. Analizando la tendencia de los errores en cada velocidad se observa un patrón diferente para ambos escenarios: los resultados en el circuito son similares a los encontrados por Recarte and Nunes (1996), a saber, disminución de la infraestimación con el aumento de la velocidad; sin embargo en autovía la infraestimación aumenta con la velocidad. Se discuten las implicaciones de los resultados con respecto a la normativa de limitación de velocidad

La estimación de la velocidad desde el punto de vista de la consistencia de los sujetos

Consistence of speed estimations. Speed perception, using a vehicle, has been studied from a psychophisical point of view, taking into account diverse variables. Nonetheless, only in a few investigations, errors have been analysed from the individual consistence point of view of. In the present research the consistence of speed estimations has been investigated in four experimental conditions: vehicle on track, vehicle on open road, video on track, and video on open road. There were thirty-six participants, half males and half females, 24.36 and 2.06 years of mean and standard deviation, respectively. Task consisted in estimating speed in a range from 40 to 120 kph or 140 kph. on the highway and closed track, respectively. Results have been analysed from the perspective of the individual ability, studying the covariation of estimation errors. Linear correlations intra experimental condition were high, ranging from .83 to .88, but correlations inter experimental conditions ranged from .21 to .52. On the other hand, for each pair of speeds in one experimental condition, the nearer speeds, the higher the correlation. These results indicate that subjects behaved as consistent estimators when they estimated speed in the same experimental paradigm, but this ability was not generalised into another experimental paradigm. We make the hypothesis that speed perception would be related to the gestalt compounded by a set of aspects in each scene, and that subjects would estimate in the same way (infra-estimating or over-estimating) those speeds with similar pattern of scenic attributes.La percepción de la velocidad con vehículo real se ha estudiado desde una perspectiva psicofísica y analizando la influencia de diversas variables sobre la misma. Sólo en algunas investigaciones se ha abordado, pero muy secundariamente, el estudio de los errores desde la perspectiva de la consistencia de los sujetos como estimadores. En la investigación presente se ha estudiado la consistencia de las estimaciones de la velocidad a través de varias condiciones experimentales: vehículo en circuito, vehículo en carretera/autovía, vídeo en circuito y vídeo en carretera/autovía. Treinta y seis sujetos, la mitad varones y la mitad mujeres, con una edad media de 24,36 años y una desviación típica de 2,06 años, estimaron la velocidad de un automóvil utilizando un rango desde 40 a 120 Km./h. ó 140 Km./h en autovía y circuito, respectivamente. Los resultados se han analizado desde la perspectiva de las habilidades individuales estudiando la covariación entre los errores de estimación. La correlaciones intra- condición experimental han sido muy altas, oscilando desde .83 hasta .88. En cambio, las correlaciones entre condiciones experimentales oscilaron desde .21 hasta .52. Por otra parte, dentro de cada condición experimental, para cada par de velocidades se observó que en la medida en que eran más cercanas la correlación entre los errores fue más alta, mientras que cuando las velocidades eran más distan tes la correlación disminuyó. Este patrón se replicó de una forma muy similar en cada una de las condiciones experimentales, indicando que los sujetos fueron altamente consistentes cuando las estimaciones se realizaron en el mismo contexto experimental, pero que su habilidad para estimar no fue generalizable a otro contexto. Estos resultados indican que la percepción de la velocidad, considerada como habilidad individual, estaría asociada a unos atributos de la escena, que se percibirían a modo de gestalt y que la forma de estimar sería generalizable a otra escena en la medida en que el patrón de atributos de la misma fuese similar

Óxidos de colesterol en langostinos frescos y congelados, crudos y a la plancha

Los óxidos de colesterol (COPs) se relacionan con diferentes efectos tóxicos entre los que destacan su implicación en los procesos de aterosclerosis. Se estudió la presencia de óxidos de colesterol en langostinos comercializados en fresco y en congelación, tanto en crudo, como sometidos a una tecnología culinaria habitual (plancha). La determinación se realizó por cromatografía de gases acoplada a espectrometría de masas (CG-EM). En los langostinos frescos se detectaron todos los COPs analizados con excepción del 7-hidroxicolesterol, presentando una cantidad total de 33,15 μg COPs/g grasa. Por el contrario, en los langostinos comercializados congelados sólo se detectaron el 7-ketocolesterol y el 7-hidroxicolesterol, dando lugar a una cantidad total de 2,38 μg COPs/g grasa. Estos resultados indican la gran efectividad de la comercialización bajo condiciones de congelación de este tipo de alimentos en cuanto a ralentizar la formación de COPs. El tratamiento culinario incrementó el contenido de COPs en ambos tipos de langostinos, alcanzando 55,43 μg COPs/g grasa en los frescos y sólo 13,06 μg COPs/g grasa en los congelados.Cholesterol oxidation products (COPs) have been related to different toxic effects, being the atherosclerotic process one of the best known. The presence of cholesterol oxides in freshly and frozenly commercialised shrimps, both raw and grilled, was studied. The determination was made by gas chromatography-mass spectrometry (GCMS). Fresh shrimps showed significant amounts of all analysed COPs, except for 7-hydroxycholesterol, accounting in total for 33.15 μg COPs/g fat. In contrast, in frozen commercialised shrimps only 7-ketocholesterol and 7-hydroxycholesterol were detected. These results point out the great effectiveness of the commercialisation of this type of products under freezing, in terms of to the minimisation of the COPs formation. The cooking method (grilling) increased the COPs content in both types of shrimps, reaching 55.43 μg COPs/g fat in fresh shrimps and only 13.06 μg COPs/g fat in frozen ones