Sterol carrier protein 2 gene transfer changes lipid metabolism and enterohepatic sterol circulation in mice

BACKGROUND & AIMS

Sterol carrier protein 2 (SCP-2) enhances sterol cycling and facilitates cholesterol translocation between intracellular organelles and plasma membrane in cultured cells, including hepatocytes. We examined the role of SCP-2 in hepatic cholesterol and lipid trafficking through the sinusoidal and canalicular secretory pathways of the liver in vivo.

METHODS

Recombinant adenovirus-mediated SCP-2 gene transfer was used to obtain hepatic overexpression of SCP-2 in C57BL/6 mice.

RESULTS

SCP-2 overexpression in the mouse liver resulted in an 8-fold increase of SCP-2 protein levels and determined various effects on lipid metabolism. It decreased high-density lipoprotein cholesterol and increased low-density lipoprotein (LDL) cholesterol concentrations. The expressions of hepatic LDL receptor, apolipoprotein (apo) A-I, apoB, and apoE were decreased. SCP-2 overexpression also increased hepatic cholesterol concentration, associated with decreased cholesterol neosynthesis. Increased biliary cholesterol and bile acid secretion, bile acid pool size, and intestinal cholesterol absorption were also observed.

CONCLUSIONS

These results indicate that modulation of SCP-2 expression in the liver determines important modifications on lipoprotein metabolism, hepatic cholesterol synthesis and storage, biliary lipid secretion, bile acid metabolism, and intestinal cholesterol absorption.

Risk factors and pathogenesis of cholesterol gallstones: state of the art

The aim of this article is to present an update of selected aspects of the pathogenesis and risk factors of cholesterol gallstones, a highly prevalent Western disease. The etiology of cholesterol cholelithiasis is considered to be multifactorial, with interaction of genetic and environmental factors. Mechanisms of cholesterol lithogenesis include biliary cholesterol hypersecretion, supersaturation and crystallization, stone formation and growth, and bile stasis within the gallbladder. Each of these various steps could be under genetic control and/or be influenced through intermediate pathogenic steps linked to a variety of environmental factors.

Enrichment of canalicular membrane with cholesterol and sphingomyelin prevents bile salt-induced hepatic damage

These studies were undertaken to characterize the role of plasma membrane cholesterol in canalicular secretory functions and hepatocyte integrity against intravenous taurocholate administration. Cholesterol and sphingomyelin concentrations and cholesterol/phospholipid ratios were significantly increased in canalicular membranes of diosgenin-fed rats, suggesting a more resistant structure against solubilization by taurocholate. During taurocholate infusion, control rats had significantly decreased bile flow, whereas diosgenin-fed animals maintained bile flow. Maximal cholesterol output increased by 176% in diosgenin-fed rats, suggesting an increased precursor pool of biliary cholesterol in these animals. Maximal phospholipid output only increased by 43% in diosgenin-fed rats, whereas bile salt output remained at control levels. The kinetics of glutamic oxalacetic transaminase, lactic dehydrogenase, and alkaline phosphatase activities in bile showed a significantly faster release in control than in diosgenin-fed rats. After 30 min of intravenous taurocholate infusion, necrotic hepatocytes were significantly increased in control animals. Preservation of bile secretory functions and hepatocellular cytoprotection by diosgenin against the intravenous infusion of toxic doses of taurocholate was associated with an increased concentration of cholesterol and sphingomyelin in the canalicular membrane. The increase of biliary cholesterol output induced by diosgenin was correlated to the enhanced concentration of cholesterol in the canalicular membrane.

[Mutations of the p53 suppressor gene in gastric adenocarcinoma]

BACKGROUND

We have shown numeric alterations such as hyperploidy and hypoploidy with loss of chromosome 17 in primary gastric cancer. This chromosome maps p53 suppressor gene that induces the transcription of genes related to cellular cycle control, DNA synthesis and repair, cellular differentiation and apoptosis.

AIM

To analyze, at a molecular level, the possible alterations of p53 suppressor gene in samples of gastric cancer and non tumoral mucosa.

MATERIAL AND METHODS

Tissue samples of gastric carcinoma and non tumoral gastric mucosa coming from 26 patients subjected to a total gastrectomy were analyzed. The mutation of p53 suppressor gene exons 7 to 9 were determined using a conformational polymorphism analysis in single strands of the gene and indirect sequencing in some cases.

RESULTS

Alterations in p53 gene were found in 77% of tumoral and 19% of non tumoral samples. T insertions in codons 260, 317 and 321, G insertion in codon 328 and G-T transvertion in codon 302 were found. Aminoacid sequence analysis of p53 protein obtained with sequencing data showed that T insertion in codon 260 could translate three erroneous aminoacids after the mutation and produce a truncated protein due to the creation of a stop codon. No associations between alterations of p53 gene and clinical or pathological variables such as age, sex, tumor localization, histological type and presence of lymph node metastases were observed.

CONCLUSIONS

Mutations of p53 suppressor gene are frequent in gastric carcinoma.

[Sweet's syndrome. Presentation of six cases and review of the literature]

The acute febrile neutrophilic dermatosis or Sweet syndrome, initially described in 1964 by Robert Sweet (1). It is characterized fever, neutrophilic leucocytosis, abrupt appearance of erythematous, painful, cutaneous plaquets and dense dermal infiltrate consisting of mature neutrophils without vasculitis sings. Malignancy has been described in the 10-15% of the reported cases. We report our series of 6 patients diagnosticated of this illness in our department. One of this patients has Sweet syndrome associated with a malignancy disorder. All of them had diagnostic criteria of the described disease and had good response to corticotherapy. We also report a bibliographic review of this infrequent syndrome.

Pituitary and adrenals are required for hyperglycemic reflex initiated by stimulation of CBR with cyanide

We have previously shown that stimulation of carotid body receptors (CBR) with sodium cyanide (NaCN) elicits a rapid hyperglycemic reflex. Here we explore whether the pituitary and adrenals, two glands involved in glucose homeostasis, are necessary for this reflex. Experiments were performed on anesthetized rats that were artificially ventilated. Measurements of hepatic venous-arterial glucose difference indicated that CBR stimulation with a bolus of 5 micrograms/100 g NaCN produced an immediate increase in the output of glucose by the liver. The same dose of NaCN failed to increase hepatic output of glucose in rats with bilateral adrenalectomy or in rats 1 wk after surgical removal of neurohypophysis. Reflex glucose output by the liver was maintained after adenohypophysectomy or in adrenalectomized rats after adrenal autotransplantation to epiploon. Measurements of epinephrine in plasma and in the grafted adrenal tissue showed that the adrenal autograft can store and secrete catecholamines Immunocytochemical observations indicated that the grafted adrenals retain medullary cells. These results indicate that neurohypophysis and adrenals are necessary for the hyperglycemic reflex initiated by CBR stimulation with NaCN and that the participation of these two organs in this reflex is probably humoral.

[Acute sinusitis, bacteremia and meningitis caused by group F beta-hemolytic Streptococcus]

A 32-year old man without immunodepression developed sinusitis followed by acute pyogenic meningitis and beta-hemolytic Streptococcus group F bacteremia. Amplicillin treatment produced a favorable outcome with sequela of righ neurosensorial deafness. Beta-hemolytic Streptococcus group F meningitis, sinusitis and bacteremia is a rare association.

[HELLP syndrome: case report and review of the literature]

The case of a 32-years-old primipara in her thirty-second week of pregnancy who presented acute epigastric pain, citopenia, elevation in hepatic enzymes and analytical signs of hemolysis is presented. Ultrasonography demonstrated multiple hyperechogenic nodular images in the liver leading to a wide differential diagnosis. Liver biopsy findings, together with the mentioned clinico-biological alterations were indicative of the HELLP syndrome. Following caesarean, the patient presented rapid and total, symptomatic and analytical, improvement. Based on this case, a review of this entity in the literature and its prognostic implications and possible therapeutic approaches are reported.

[Dysphagia as an unusual form of presentation of malignant pleural mesothelioma]

Dysphagia is an unusual presenting symptom as of extradigestive tumors. Malignant mesothelioma, is a rare tumor localized in the pleural cavity in 80% of all cases and it rarely appears with dysphagia as first symptom. We describe the case of a 74-year-old woman admitted with progressive dysphagia for solid and liquid food, atypical epigastric pain, with in conclusive endoscopic and radiologic studies. Nuclear Magnetic Resonance established the diagnostic suspicion of malignant mesothelioma which was confirmed by the histologic study of a biopsy taken by thoracotomy. We think of interest to report this case of paraesophageal mesothelioma because of its unusual localization and presentation.

[Muscular tumors of the digestive tract: an analysis of 53 cases]

We present 53 cases of gastrointestinal smooth tumors (43 leiomyomas and 10 leiomyosarcomas) which have being diagnosed in Virgen del Camino Hospital during a period of 17 years. The aim of the research is to know the incidence of such tumors, their clinical presentation, the usefulness of radiologic and endoscopic studies for their diagnosis, as soon as to make a bibliographic revision of new diagnostic and therapeutic methods. This kind of tumor had an incidence of 3.1 cases per year. The symptomatology because of which the patients consulted depended on the location and the size of the tumors, though 18% of the cases were asymptomatic and were found in surgical operations. Endoscopic biopsy had a diagnostic sensibility of 28%; it didn't obstruct later exeresis. It has to be emphasized that, according to our bibliographic revision, there is a growing importance of endoscopic echography, not only as for diagnosis, but also as for non surgical treatment of this kind of tumor. Endoscopic resection can be a valid alternative for exeresis of small tumors (less than 2 cm according to some authors); haemorrhage is the most frequent complication, though it can be easily controlled.

[Hepatic markers (Ac-HVA-IgM and AcHBc-IgM) in cases of infectious hepatitis in Dominican children]

The presence of IgM antibodies for the HVA and HBc antigens in 90 children of 15 or less years with acute hepatitis were investigated, finding that 62% (58) were positive for HVA, 8.9% (8) for HBc and 27.8% (25) did not show antibodies for HVA or HBc (non-A non-B hepatitis); comments are made on some clinical and epidemiological findings such as a higher frequency of blood transfusions in HNANB, more males in HB and HNANB, and more hepatomegaly and liver sensitivity in HNANB.