Impact of hyperhomocysteinemia on histo-morphometry and histochemistry of pancreas in sand rat, Psammomys obesus

Introduction. The sand rat, Psammomys obesus, a diurnal rodent, which lives in the south-east of the Algerian Sahara, is an excellent animal model for the study of diabetes, atherosclerosis, and metabolic syndrome. Hyperhomocysteinemia (Hhcy), defined by high plasma homocysteine level, is associated with many diseases affecting various organs (heart, blood vessels, liver…). Objectives. The objective of this study was to determine the effect of Hhcy on the sand rats pancreas. Material and methods. The rats were divided into two groups: a control group received its natural diet with halophile plant of the Chenopodiacae family (Suaedamollis), and an experimental group received the same diet associated with an intraperitoneal administration of methionine (150 mg/kg body weight/day) during 6 months. Histological and histochemical analysis of Psammomys pancreas were realized and completed by a morphometric study. Results. The methionine excess led to a hyperhomocysteinemia in Psammomys obesus. Several alterations were observed in pancreas extracellular matrix of hyperhomocysteinemic rats, marked by an accumulation of fibrillar collagens, and glycoproteins leading to a fibrosis. This accumulation was observed in the Langerhans islets, and in the exocrine pancreas (interstitial tissue, around blood vessels, and excretory channels). A disorganization of the vascular wall, and a micro- and macrovesicular steatosis were also observed in the pancreas of hyperhomocysteinemic rats. Conclusion. The hyperhomocysteinemia, generated by the methionine excess, leads to a pancreatic extracellular matrix remodeling in Psammomys obesus

Effet in vitro du glucose sur le fibroblaste adventitiel aortique de Psammomys obesus

L‟athérosclérose est la principale cause de décès dans les pays occidentaux et apparaît en nette progression dans les pays en voie de développement. Plusieurs études cliniques et épidémiologiques ont montré que le diabète est associé à cette maladie et pourrait donc représenter un facteur de risque. Nous avons analysé l‟effet du glucose à forte concentration (15 mM) sur des fibroblastes adventitiels aortiques en culture à un passage précoce (P6) chez Psammomys obesus, excellent modèle pour l‟étude des maladies cardio-vasculaires. Cette étude in vitro a concerné la prolifération cellulaire ainsi que quelques paramètres cellulaires et nucléaires. Cette étude met en évidence une augmentation significative de la prolifération des fibroblastes adventitiels incubés en présence d‟un milieu enrichi en glucose ainsi qu‟une augmentation de leur diamètre, de leurs grands et petits axes nucléaires et du nombre de nucléoles. Mots clés : Athérosclérose - Fibroblaste adventitiel - Glucose - Paroi artérielle - Psammomys obesus

Impact d’une hyperhomocystéinémie sur les lipoprotéines plasmatiques et sur la structure hépatique du Rat des sables, Psammomys obesus

Durant les dernières décennies, plusieurs études ont montré que l‟hyperhomocystéinémie est associée aux maladies cardiovasculaires. Nous avons également mis en évidence, cette association chez le Rat des sables, Psammomys obesus. Un état d‟hyperhomocystéinémie est installé par une administration chronique d‟un excès de méthionine à raison de 70 mg/kg de poids corporel/jour durant 6 mois sur un modèle athéro-sensible à savoir Psammomys obesus. L‟objectif de ce travail est d‟analyser d‟une part, l‟impact de cette hyperhomocystéinémie sur les lipoprotéines plasmatiques et, d‟autre part, sur la structure histologique et histochimique du foie de ce modèle. L‟administration d‟un excès de méthionine a provoqué chez Psammomys, l‟apparition de la lipoprotéine (a), une augmentation des VLDL-LDL (Very Low Density Lipoprotein et Low Density Lipoprotein), molécules athérogènes et une diminution spectaculaire des HDL (High density lipoprotein), molécules cardioprotectrices. Le foie de Psammomys obesus hyperhomocystéinémique est le siège de plusieurs altérations focalisées représentées essentiellement par une fibrose interstitielle et périvasculaire, un changement de forme des noyaux des hépatocytes et une stéatose hépatique.Mots clés : Méthionine ; Hyperhomocystéinémie ; Foie ; Psammomys obesus ; Athérosclérose

Sintering and mechanical properties of porcelains prepared from algerian raw materials Sinterização e propriedades mecânicas de porcelanas preparadas com matéria-prima argelina

Porcelain is a type of ceramics highly valued for its beauty and strength. The overall goal of this work is to utilize local raw materials within the following fractions: 37 wt.% kaolin, 35 wt.% feldspar and 28 wt.% quartz. This composition has been selected on the basis of the ternary phase diagrams (kaolin-feldspar-quartz). The densification behaviour indicated that specimens sintered at 1200 °C for 2 h with a heating rate of 5 °C/min, have a bulk density of about 2.50 g/cm³. This value is slightly higher than that reported for the conventional porcelain products (2.45 g/cm³). Porcelain specimens with and without calcination sintered at 1200 °C for 2 h have tensile strength values of about 45 and 73 MPa, respectively (equivalent flexural strength values of about 122 and 197 MPa, respectively). The flexural strength values of both specimens are much higher than those reported for conventional porcelains (ranged between 60 and 80 MPa). Furthermore, the value of micro-hardness of the fired samples without calcination at 1200 °C is 9.3 ± 0.2 GPa which is higher than the commercial porcelain products (5.5 GPa).<br>A porcelana é um tipo de cerâmica altamente valorizada pela sua beleza e resistência mecânica. O objetivo geral deste trabalho é utilizar matérias-primas locais nas seguintes frações: 37% em peso de caulim, feldspato 35% em peso e 28% em peso de quartzo. Esta composição foi escolhida com base em diagramas de fase ternários (caulim, feldspato-quartzo). O comportamento de densificação indicou que amostras sinterizadas a 1200 °C por 2 h com taxa de aquecimento de 5 °C/min, tem uma densidade de cerca de 2,50 g/cm³. Este valor é ligeiramente superior ao relatado para os produtos de porcelana convencional (2,45 g/cm³). Espécimes de porcelana, com e sem calcinação sinterizadas a 1200 °C por 2 h têm valores de resistência à tração de cerca de 45 e 73 MPa, respectivamente (valores equivalentes de resistência à flexão de aproximadamente 122 e 197 MPa, respectivamente). Os valores de resistência à flexão de ambos os espécimes são muito superiores aos relatados para porcelanas convencionais (variou entre 60 e 80 MPa). Mais ainda, o valor da micro-dureza das amostras sem calcinação a 1200 °C é de 9,3 ± 0,2 GPa que é maior do que os produtos comerciais de porcelana (5,5 GPa)