Impaired autophagic flux is associated with increased endoplasmic reticulum stress during the development of NAFLD

This work is licensed under a Creative Commons Attribution-NonCommercialNoDerivs 3.0 Unported License.-- et al.The pathogenic mechanisms underlying the progression of non-alcoholic fatty liver disease (NAFLD) are not fully understood. In this study, we aimed to assess the relationship between endoplasmic reticulum (ER) stress and autophagy in human and mouse hepatocytes during NAFLD. ER stress and autophagy markers were analyzed in livers from patients with biopsy-proven non-alcoholic steatosis (NAS) or non-alcoholic steatohepatitis (NASH) compared with livers from subjects with histologically normal liver, in livers from mice fed with chow diet (CHD) compared with mice fed with high fat diet (HFD) or methionine-choline-deficient (MCD) diet and in primary and Huh7 human hepatocytes loaded with palmitic acid (PA). In NASH patients, significant increases in hepatic messenger RNA levels of markers of ER stress (activating transcription factor 4 (ATF4), glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP)) and autophagy (BCN1) were found compared with NAS patients. Likewise, protein levels of GRP78, CHOP and p62/SQSTM1 (p62) autophagic substrate were significantly elevated in NASH compared with NAS patients. In livers from mice fed with HFD or MCD, ER stress-mediated signaling was parallel to the blockade of the autophagic flux assessed by increases in p62, microtubule-associated protein 2 light chain 3 (LC3-II)/LC3-I ratio and accumulation of autophagosomes compared with CHD fed mice. In Huh7 hepatic cells, treatment with PA for 8 h triggered activation of both unfolding protein response and the autophagic flux. Conversely, prolonged treatment with PA (24 h) induced ER stress and cell death together with a blockade of the autophagic flux. Under these conditions, cotreatment with rapamycin or CHOP silencing ameliorated these effects and decreased apoptosis. Our results demonstrated that the autophagic flux is impaired in the liver from both NAFLD patients and murine models of NAFLD, as well as in lipid-overloaded human hepatocytes, and it could be due to elevated ER stress leading to apoptosis. Consequently, therapies aimed to restore the autophagic flux might attenuate or prevent the progression of NAFLD.We acknowledge the following grant support: SAF2012-33283 (MINECO, Spain), Comunidad de Madrid S2010/BMD-2423, EFSD and Amylin Paul Langerhans Grant and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM, ISCIII, Barcelona, Spain) to AMV.; SAF2010-16037, SAF2013-43713-R (MINECO) and Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD, ISCIII) to PMS. RD12/0042/0019 (ISCIII) and S2010/BMD-2478 (Comunidad de Madrid) to LB, PI 13/01299 and Fundación Mutua Madrileña 2012 to C G-M and AIRC IG-2012 to GMF.Peer Reviewe

Extracción de pectinas

Pectins are a group of substances formed from polysaccharides, which are found in the intercellular spaces at the level of the average of vegetables. They allow the binding of the cells and the absorption of large quantities of to transfer them to cells distant from the tissues of the conductors that maintain firmness and texture of the fruits. This practice had as objective the obtaining and characterization of the pectins from the husk of various fruits,, which was carried out by means of the extraction by hydrolysis in acid medium and then with ethyl alcohol, obtaining the following results: small ripe orange (26, 76g), large ripe orange (24.73 g), green orange (14.58), lemon (1.90) and passion fruit (0).Las pectinas son un grupo de sustancias formadas a partir de polisacáridos, que se encuentran en los espacios intercelulares a nivel de la lámina media de los vegetales. Permiten la ligazón de las células y la absorción de grandes cantidades de H2 O, para transferirlas a aquellas células distantes de los tejidos conductores aportando firmeza y textura a los frutos. En el presente trabajo de investigación se tuvo como objetivo la obtención de pectinas a partir de la cascara de diversos frutos; se llevó a cabo mediante extracción por hidrólisis en medio ácido y precipitación con alcohol etílico. Los mejores resultados se alcanzaron con cáscara de naranja madura y cortes pequeños (menores a 3.0 mm2 ), seguidos con la utilización de naranja madura pero con cortes grandes (mayores a 3.0 mm2 ); la naranja verde presentó un contenido intermedio de pectinas, mientras la cáscara de limón y de maracuyá mostraron bajos contenidos de pectinas

Extracción de pectinas

Pectins are a group of substances formed from polysaccharides, which are found in the intercellular spaces at the level of the average of vegetables. They allow the binding of the cells and the absorption of large quantities of to transfer them to cells distant from the tissues of the conductors that maintain firmness and texture of the fruits. This practice had as objective the obtaining and characterization of the pectins from the husk of various fruits,, which was carried out by means of the extraction by hydrolysis in acid medium and then with ethyl alcohol, obtaining the following results: small ripe orange (26, 76g), large ripe orange (24.73 g), green orange (14.58), lemon (1.90) and passion fruit (0).Las pectinas son un grupo de sustancias formadas a partir de polisacáridos, que se encuentran en los espacios intercelulares a nivel de la lámina media de los vegetales. Permiten la ligazón de las células y la absorción de grandes cantidades de H2 O, para transferirlas a aquellas células distantes de los tejidos conductores aportando firmeza y textura a los frutos. En el presente trabajo de investigación se tuvo como objetivo la obtención de pectinas a partir de la cascara de diversos frutos; se llevó a cabo mediante extracción por hidrólisis en medio ácido y precipitación con alcohol etílico. Los mejores resultados se alcanzaron con cáscara de naranja madura y cortes pequeños (menores a 3.0 mm2 ), seguidos con la utilización de naranja madura pero con cortes grandes (mayores a 3.0 mm2 ); la naranja verde presentó un contenido intermedio de pectinas, mientras la cáscara de limón y de maracuyá mostraron bajos contenidos de pectinas

Energy recovery method of damping oscillations of the vehicle suspension

Abstract. The paper analyses the existing methods of energy recovery of vehicle suspension oscillation damping. It reveals the most preferred method in which an electromagnetic device of rotational type with a ball screw gear is used. The influence of the road parameters on the dynamic loads in the drive of an electromechanical generator is etermined by mathematical modellin

Impaired autophagic flux is associated with increased endoplasmic reticulum stress during the development of NAFLD.

The pathogenic mechanisms underlying the progression of non-alcoholic fatty liver disease (NAFLD) are not fully understood. In this study, we aimed to assess the relationship between endoplasmic reticulum (ER) stress and autophagy in human and mouse hepatocytes during NAFLD. ER stress and autophagy markers were analyzed in livers from patients with biopsy-proven non-alcoholic steatosis (NAS) or non-alcoholic steatohepatitis (NASH) compared with livers from subjects with histologically normal liver, in livers from mice fed with chow diet (CHD) compared with mice fed with high fat diet (HFD) or methionine-choline-deficient (MCD) diet and in primary and Huh7 human hepatocytes loaded with palmitic acid (PA). In NASH patients, significant increases in hepatic messenger RNA levels of markers of ER stress (activating transcription factor 4 (ATF4), glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP)) and autophagy (BCN1) were found compared with NAS patients. Likewise, protein levels of GRP78, CHOP and p62/SQSTM1 (p62) autophagic substrate were significantly elevated in NASH compared with NAS patients. In livers from mice fed with HFD or MCD, ER stress-mediated signaling was parallel to the blockade of the autophagic flux assessed by increases in p62, microtubule-associated protein 2 light chain 3 (LC3-II)/LC3-I ratio and accumulation of autophagosomes compared with CHD fed mice. In Huh7 hepatic cells, treatment with PA for 8 h triggered activation of both unfolding protein response and the autophagic flux. Conversely, prolonged treatment with PA (24 h) induced ER stress and cell death together with a blockade of the autophagic flux. Under these conditions, cotreatment with rapamycin or CHOP silencing ameliorated these effects and decreased apoptosis. Our results demonstrated that the autophagic flux is impaired in the liver from both NAFLD patients and murine models of NAFLD, as well as in lipid-overloaded human hepatocytes, and it could be due to elevated ER stress leading to apoptosis. Consequently, therapies aimed to restore the autophagic flux might attenuate or prevent the progression of NAFLD

Increased hepatic CD36 expression with age is associated with enhanced susceptibility to nonalcoholic fatty liver disease

CD36 has been associated with obesity and diabetes in human liver diseases, however, its role in age-associated nonalcoholic fatty liver disease (NAFLD) is unknown. Therefore, liver biopsies were collected from individuals with histologically normal livers (n=30), and from patients diagnosed with simple steatosis (NAS; n=26). Patients were divided into two groups according to age and liver biopsy samples were immunostained for CD36. NAFLD parameters were examined in young (12-week) and middle-aged (52-week) C57BL/6J mice, some fed with chow-diet and some fed with low-fat (LFD; 10% kcal fat) or high-fat diet (HFD; 60% kcal fat) for 12-weeks. CD36 expression was positively associated with age in individuals with normal livers but not in NAS patients. However, CD36 was predominantly located at the plasma membrane of hepatocytes in aged NAS patients as compared to young. In chow-fed mice, aging, despite an increase in hepatic CD36 expression, was not associated with the development of NAFLD. However, middle-aged mice did exhibit the development of HFD-induced NAFLD, mediated by an increase of CD36 on the membrane. Enhanced CD36-mediated hepatic fat uptake may contribute to an accelerated progression of NAFLD in mice and humans. Therapies to prevent the increase in CD36 expression and/or CD36 from anchoring at the membrane may prevent the development of NAFLD