1,721,110 research outputs found
Lipoprotein-X fifty years after its original discovery
No full textAims: To review the formation, catabolism, and the possible atherogenic properties of Lp-X. Data Synthesis: The conversion of cholesterol to bile acids is regulated by several mechanisms including cholesterol 7 alpha hydroxylase, fibroblast growth factor 19, and farnesoid X receptors. During cholestasis these mechanisms are altered and there is an accumulation of bile acids and cholesterol in plasma. The hypercholesterolemia observed in cholestasis is due to the presence of an anomalous lipoprotein called lipoprotein-X (Lp-X). Lp-X is a lipoprotein rich in phospholipid and free cholesterol present in plasma of patients with cholestasis and, with some variations, in patients with lecithin-cholesterol-acyl-transferase deficiency (LCAT), and after lipid infusion. Lp-X is formed from a bile lipoprotein moving to the blood vessels where it incorporates small quantities of triglycerides, apo-C and esterified cholesterol and becomes a “mature” Lp-X. The activity of the phosphatidilcholine canalicular transporter Mdr2 P-glycoprotein (homologous to the human ABCB4) is essential for LpX appearance, since its suppression abolishes Lp-X formation. However, the concentration of Lp-X in plasma is determined also by the degree of the cholestasis, the residual liver function, and the LCAT deficiency. The Lp-X catabolism seems to be mediated by the reticuloendothelial system and possibly the kidney. Conclusions: Lp-X might be considered a defense mechanism against the toxic effect of free cholesterol in cholestasis. The frequency of cardiovascular events in patients affected by primary biliary cholangitis, in whom the Lp-X is present in high concentration, are not increased. Further studies could now clarify the remaining open questions on the role of Lp-X in the dyslipidemia of cholestasis
La prevenzione secondaria della cardiopatia coronarica nell’anziano
No full textThe World Health Organization (WHO) estimated that 48% of death in industrialized countries is caused by cardiovascular diseases. In elderly subjects cardiovascular diseases are the first cause of morbidity and mortality, and it has been estimated that about 80% of deaths from coronary heart disease occur in this specific class of age. The guidelines for the primary prevention of coronary heart disease have been already well established, but recently also the secondary prevention has been turned in account in the light of new knowledges like the high cost/benefit ratio of primary prevention, the observation that in patients with coronary heart disease the incidence of new events is still related to the risk factors, the success of several secondary prevention trials. The main objective of secondary prevention is to slow the progression of coronary atherosclerosis and to reduce the risk for thrombotic complications, reducing in this way the incidence of new coronary fatal and non-fatal ..
Extreme but asymptomatic hypergastrinemia with gastroparesis in a young woman with insulin dependent diabetes mellitus.
No full textFamilial chylomicronemia syndrome. A sixty year follow-up in two siblings and their kindreds. Nosological and clinical considerations
No full textFamilial chylomicronemia syndrome (FCS) is a rare and severe genetic disorder, characterized by marked elevation of plasma triglycerides, often diagnosed in infancy. We describe the long-term follow-up (almost 60 years), the diagnostic assessment and the management of two siblings with severe hypertriglyceridemia and a history of pancreatitis who also developed cardiovascular complications later in life. We recently disclosed that the surviving index case was homozygous for a pathogenic LPL gene variant (c.984 G>T, p.M328I). The same variant was also found in two apparently unrelated siblings with FCS living in the same geographical area as the index case
The history of Autosomal Recessive Hypercholesterolemia (ARH): from clinical observation to gene identification
No full textThe most frequent form of monogenic hypercholesterolemia, also known as Familial Hypercholesterolemia (FH), is characterized by plasma accumulation of cholesterol transported in Low Density Lipoproteins (LDLs). FH has a co-dominant transmission with a gene-dosage effect. FH heterozygotes have levels of plasma LDL-cholesterol (LDL-C) twice normal and present xanthomas and coronary heart disease (CHD) in adulthood. In rare FH homozygotes plasma LDL-C level is four times normal, while xanthomas and CHD are present from infancy. Most FH patients are carriers of mutations of the LDL receptor (LDLR); a minority of them carry either mutations in the Apolipoprotein B (ApoB), the protein constituent of LDLs which is the ligand for LDLR, or gain of function mutations of PCSK9, the protein responsible for the intracellular degradation of the LDLR. From 1970 to the mid 90s some publications described children with the clinical features of homozygous FH, who were born from normocholesterolemic parents, strongly suggesting a recessive transmission of FH. In these patients the involvement of LDLR and APOB genes was excluded. Interestingly, several patients were identified in the island of Sardinia (Italy), whose population has a peculiar genetic background due to geographical isolation. In this review, starting from the early descriptions of patients with putative recessive hypercholesterolemia, we highlight the milestones that led to the identification of a novel gene involved in LDL metabolism and the characterization of its encoded protein. The latter turned out to be an adaptor protein required for the LDLR-mediated endocytosis of LDLs in hepatocytes. The loss of function of this protein is the cause of Autosomal Recessive Hypercholesterolemia (ARH
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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