Relevance of hepatic lipase to the metabolism of triacylglycerol-rich lipoproteins.

HL (hepatic lipase) is a glycoprotein that is synthesized and secreted by the liver, and which binds to heparan sulphate proteoglycans on the surface of sinusoidal endothelial cells and on the external surface of parenchymal cells in the space of Disse. HL catalyses the hydrolysis of triacylglycerols and phospholipids in different lipoproteins, contributing to the remodelling of VLDL (very-low-density lipoprotein) remnants, as well as IDL, LDL and HDL (intermediate-, low- and high-density lipoprotein respectively). HL deficiency in humans is associated with diminished conversion of VLDL remnants into IDL and a near-complete absence of IDL-to-LDL conversion. Remnant lipoproteins and IDL are major determinants of coronary artery disease risk, and accumulation of these lipoproteins in the presence of low HL activity might lead to increased atherosclerosis. In addition to and independently of its lipolytic activity, HL participates as a ligand in promoting the hepatic uptake of remnants and IDL particles, and the latter may represent an additional mechanism linking low HL levels to plasma accumulation of these atherogenic lipoproteins. On the other hand, high HL activity may also result in an increased atherosclerotic risk by promoting the formation of atherogenic small, dense LDL particles. Finally, HL is also synthesized by human macrophages, suggesting that, at the arterial wall site, HL may also contribute locally to promote atherosclerosis by enhancing the formation and retention in the subendothelial space of the arterial wall of VLDL remnants, IDL and small, dense LDL. In conclusion, by interfering with the metabolism of apolipoprotein B100-containing lipoproteins, HL may have pro- as well as anti-atherogenic effects. The anti- or pro-atherogenic role of HL is likely to be modulated by the concurrent presence of other lipid abnormalities (i.e. LDL-cholesterol levels), as well as by the genetic regulation of other enzymes involved in lipoprotein metabolism.

[Subjects of the risk assessment]. / I soggetti della valutazione del rischio.

The Dlgs 626/94 describes a safety management system based on organizational and procedural actions, and leaves technical actions to a discretionary/secondary moment. This article debates how safety in the workplace takes place through planning and engineering of prevention measures. The most important mechanism is the "Risk Evaluation Proceeding", a process which encompasses three main steps: risks identification prevention measures identification planning of health/medical examinations and information/formation activities Due to the complexity of the risk evaluation, law obliges the employer to perform the process together with the Safety Manager, the Health Manager (Competent Persons), and after discussing with the Safety Representative. The writing specifically analyses the roles of the aforementioned actors in the risk evaluation proceeding, their civil as well as penal responsibilities.

Reduced susceptibility to oxidation of low-density lipoprotein in patients with overproduction of nitric oxide (Bartter's and Gitelman's syndrome).

BACKGROUND: The oxidation of low-density lipoprotein (LDL) might play an important role in the development of atherosclerosis. OBJECTIVE: To establish whether greater than normal production of nitric oxide (NO) in vivo protects LDL from oxidation. PATIENTS AND METHODS: We studied nine subjects affected by Bartter's and Gitelman's syndrome (both characterized by greater than normal production of NO), and 10 subjects matched for age, sex and lipid levels as controls. LDL particles were isolated from plasma by density gradient ultracentrifugation. Susceptibility of LDL to oxidation was evaluated after incubation with copper sulfate solution, by measuring the formation of conjugated dienes, the thiobarbituric acid-reactive substances, and the volatile peroxidation products of n-3 (propanal) and n-6 (pentanal and hexanal) polyunsaturated fatty acids. Phospholipid fatty acid composition of LDL was determined by gas chromatography. LDL alpha-tocopherol concentrations were measured. RESULTS: Patients with Bartter's and Gitelman's syndrome had LDL particles smaller and/or denser than those of controls [Rf = 0.38 +/- 0.03 versus 0.42 +/- 0.02 (mean +/- SD), P < 0.01], which hence were assumed to be more oxidizable. The phospholipid fatty acid composition of LDL and the alpha-tocopherol concentrations did not significantly differ between patients and controls. The duration of the lag phase, which is the time preceding formation of conjugated dienes, did not differ between groups, but the lag phase times were related to urinary excretion of nitrite/nitrate from patients (r = 0.66, P < 0.05). Moreover, patient LDL had produced less thiobarbituric acid-reactive substances after 5 h (P < 0.04), and less pentanal and hexanal after 5 and 6 h (P < 0.04 and P < 0.02, respectively) than had that of controls. CONCLUSIONS: Greater than normal production of NO in vivo is associated with lower than normal susceptibility of LDL to oxidation in vitro, suggesting that NO plays a protective role in the development of atherosclerosis.

[Mixed venous oxygen saturation monitoring in selected patients in heart surgery]. / Monitoraggio della SvO2 in pazienti selezionati in cardiochirurgia.

Continuous SvO2 was monitored in 25 patients undergoing cardiac surgery, selected by preoperative conditions, risk and perioperative indications. SvO2 trends were compared to cutaneous temperature, left atrial pressure and pulse oximetry. The results indicate a good correlation of all trends.

Multiple chromosomal associations and paracentromeric region instability in a case of acute leukemia.

A case of acute myelomonocytic leukema is described, which was characterized cytogenetically by the presence of centromeric elongations, somatic crossovers, selective endoreduplication figures, and multiple chromosomal clusters. The demonstration of these phenomena by selective staining techniques for the chromosome bands (Q, C, G and S) and the nucleolar areas (acridine-orange, amido black B 10) raises some biological aspects involved in the proliferation of leukemic cells, such as nucleolar persistance during the metaphase and the non-separation of chromatids in the clusters during the anaphase. These structural abnormalities may represent the background for the explanation of the appearance of subclones in neoplastic disorders.