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S Dessi

Publications and source records attributed to S Dessi.

At least 19 recordsLinked to original sources
PubMed2005

Dietary restriction counteracts age-related changes in cholesterol metabolism in the rat.

The effects of ageing on the metabolism of cholesterol were examined in three different organs (liver, aorta and brain) of 6-, 12- and 24-month-old male Sprague-Dawley rats. Ageing was associated with a significant increase in intracellular cholesterol esters in all three organs. Steady state mRNA levels of multidrug resistance protein (MDR) and acylCoA:cholesterol acyl transferase (ACAT), enzymes involved in cholesterol import and esterification, were also increased. By contrast, expression of mRNA for neutral cholesterol ester hydrolase (nCEH) and caveolin-1, proteins involved in cholesterol ester hydrolysis and export, were significantly reduced. Dietary restriction is the only intervention shown to extend lifespan and retard age-related declines in function in mammals. To further explore the possible correlation between changes in cholesterol esterification and ageing, we analysed cholesterol metabolism in liver, aorta, and brain of aged rats exposed to two dietary restriction regimens: intermittent (alternate-day) fasting (IF) and food intake restriction (60% of ad libitum feeding). Both dietary regimens attenuated the age-related changes in cholesterol esters and in the expression of genes involved in cholesterol metabolism. These results provide evidence that distinctive age-associated changes in intracellular cholesterol metabolism occur in rats. Furthermore, these modifications can be partially reversed by dietary restriction, a condition known to affect the ageing process. Age-related changes in cholesterol metabolism may play a role in triggering and/or aggravating senescence-related disorders characterized by altered cholesterol homeostasis.

Aging↗
PubMed2000

Cell cholesterol esters and high-density lipoprotein plasma levels during liver hyperplasia in choline-fed male and female rats.

Sexual dimorphism exists in the response of rats to lead nitrate, liver hyperplasia occuring earlier and being more pronounced in males. Excess dietary choline in females shifted the growth pattern towards that of males. To determine whether phosphatidylcholine-induced growth modulations could be related to a derangement of cholesterol metabolism, liver accumulation of cholesterol esters and plasma lipoprotein patterns were investigated. In males, lead-induced liver hyperplasia was associated with increased total cholesterol hepatic content, accumulated cholesterol esters and reduced concentration of plasma High Density Lipoprotein (HDL) cholesterol. Females were less responsive to the liver mitogenic signal of lead nitrate; there was no elevation of cholesterol content nor any marked accumulation of cholesterol esters. This is consistent with the lack of change in the plasma levels of HDL cholesterol. Continuous choline feeding displaced the liver cholesterol ester pattern and plasma HDL cholesterol levels in females, and in parallel that of DNA synthesis, towards those of males. Choline was not observed to have any effect in males. These results suggest that the derangement of phosphatidylcholine metabolism induces growth-related changes in cholesterol turnover; they are consistent with the proposal that the intracellular content of cholesterol esters may have a role in regulating liver growth rates.

Animals↗
PubMed1997

Role of cholesterol synthesis and esterification in the growth of CEM and MOLT4 lymphoblastic cells.

CEM and MOLT4 are human T-cell lines isolated from patients with acute cell leukaemia. In culture they show important differences in cholesterol metabolism, CEM being less efficient at synthesizing cholesterol and having a lower activity of 3-hydroxy-3-methylglutaryl-CoA (HMGCoA) reductase. To investigate further the relationship between regulation of intracellular cholesterol metabolism at various steps and rate of cell growth, cholesterol synthesis, esterification and efflux were evaluated in CEM and MOLT4 cells at different times during exponential and stationary growth in vitro. It was shown that, although CEM cells have a lower rate of cholesterol synthesis, they grow at a faster rate than MOLT4 cells. However, CEM cells exhibit an increased capacity to esterify cholesterol associated with a decreased efflux of newly synthesized cholesterol into the medium. These results provide evidence for an association between the capability to synthesize and retain cell cholesterol esters and the growth rate potential.

Acetates↗
PubMed1995

HDL subfractions as altered in cancer patients.

Previous studies from the authors' laboratories have shown that cancer patients are characterized by lower levels of high-density lipoprotein cholesterol (HDL-C) compared with those of normal subjects. HDLs are a complex class of lipoproteins which can be divided mainly into two categories, HDL2 and HDL3, that have not only different lipid and protein composition but also different functions. Therefore, for a better understanding of the metabolism of HDL during tumour growth, the different subfractions of HDL (HDL2 and HDL3) were analysed in the serum of neoplastic patients using a rapid and simple high-performance liquid chromatography (HPLC) method for the analysis. The results obtained showed that serum from neoplastic patients exhibits a peculiar pattern in the distribution of HDL subfractions, consisting of a sharp decrease in HDL3 and a consequent increase of the normal HDL2/HDL3 ratio. It is suggested that evaluation of the HDL subfractions may be of clinical relevance for cancer status and that due to its simplicity, short analytical time and small sample volume required, the HPLC technique used in this study can be easily applied to routine analysis in cancer patients.

Adult↗
PubMed1992

Serum lipoprotein profile in the Mediterranean variant of glucose-6-phosphate dehydrogenase deficiency.

Sardinian males with erythrocyte glucose-6-phosphate dehydrogenase (G-6-PD) deficiency have lower serum levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and apolipoprotein B (ApoB), compared to normals. Since the enzyme deficiency is expressed also in nucleated cells, we studied cholesterol (C) and DNA synthesis and LDL-receptor expression in freshly isolated circulating mononuclear cells from normal and G-6-PD-deficient Sardinians. Synthesis of C (as 14C-acetate incorporation) and of DNA (as 3H-thymidine incorporation) was clearly reduced, both in basal state and after PHA stimulation, in G-6-PD-deficient cells compared to normal cells. On the other hand, no clear influence of G-6-PD deficiency on LDL-receptor expression could be demonstrated. The Mediterranean variant of G-6-PD deficiency is characterized, whatever the metabolic mechanism may be, by a serum lipoprotein pattern of reduced atherogenicity.

Adult↗
PubMed1992

Altered pattern of lipid metabolism in patients with lung cancer.

Cholesterol distribution in tumoral tissues and lipid composition in the plasma compartment were determined in patients affected by different histologic types of lung cancer. The results showed that tumoral lung tissues contained 2-fold more total cholesterol and 3.5-fold more esterified cholesterol than normal lung tissues. In the patients the alterations in intracellular cholesterol were also associated with peculiar changes in cholesterol distribution in the plasma compartment. Serum high-density lipoprotein (HDL) cholesterol levels were markedly lower in than in controls. No significant changes in other lipid parameters were observed in these patients. We suggest that the reduced levels of serum HDL cholesterol observed in patients with lung tumors may be a consequence of the disease, probably mediated by the greater utilization of cholesterol for new membrane biogenesis and by the accumulation of esterified cholesterol in tumoral tissues.

Adult↗
PubMed1988

Relationship between DNA and cholesterol synthesis in kidney after refeeding.

DNA and cholesterol synthesis were investigated in the kidneys of fasted-refed rats. Refeeding resulted in an increase in kidney DNA synthesis, as measured by 3H-thymidine incorporation, starting at 72 h. The increase in DNA synthesis was accompanied by a stimulation of cholesterol synthesis, as measured by 14C-acetate incorporation into cholesterol.

Animals↗
PubMed1988

Comparative effects of insulin and refeeding on DNA synthesis, HMP shunt and cholesterogenesis in diabetic and fasted rats.

DNA synthesis, cholesterogenesis and the enzymes of the hexosemonophosphate (HMP) shunt pathway were investigated in liver of diabetic rats treated with insulin and in fasted/re-fed rats. Both insulin and refeeding were found to induce liver cell proliferation, accompanied by a remarkable increase in cholesterogenesis. An enhancement of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (G6PD) activities was also found in insulin-treated diabetic rats and in re-fed rats, supporting the concept that these two enzymes are involved in the proliferative process. Since insulin did not exert the same biochemical effects in a non replicating cell population, such as in insulin-treated normal rats, these studies provide new evidence of a close correlation between DNA, cholesterol synthesis and HMP shunt enzymes during cell proliferation.

Animals↗
PubMed1987

Hexose monophosphate shunt and cholesterogenesis in lead-induced kidney hyperplasia.

De novo cholesterol synthesis and hexose monophosphate (HMP) shunt were studied in rat kidney stimulated to proliferate by a single administration of lead nitrate. Lead-treated rat kidneys showed an increase in DNA synthesis, as measured by [3H]thymidine incorporation starting at 18 h and with a maximum at 24 h. Renal DNA synthesis was preceded by an increase in de novo cholesterol synthesis and an enhancement in the activity of the HMP shunt, as indicated by increased activity of G6PDH and 6PGDH. These findings indicate that enhancement of cholesterol synthesis and of the HMP shunt is closely associated with the active proliferative process induced in the kidney by treatment with lead nitrate.

Animals↗
PubMed1986

Acinar cell carcinoma of rat pancreas: regulation of cholesterol esterification.

The regulation of cholesterol esterification during cell proliferation was studied. The serum free cholesterol, cholesterol esters and lecithin: cholesterol acyltransferase (LCAT) activity of nude mice with and without pancreatic acinar cell tumours and rats with proliferating tissues were determined. In addition, the apparent activity of acyl-CoA: cholesterol acyltransferase (ACAT) in homogenates of nude mouse tumours and proliferating rat tissues were determined and compared with those of normal nude mouse and rat tissues. Serum cholesterol ester levels were significantly lower in host nude mice with tumours and in rats with regenerating liver, and increased significantly in pregnant rats when compared with respective controls. Circulating LCAT activity levels decreased in host nude mice, in pregnant rats, and in rats with regenerating pancreas and regenerating liver. Apparent ACAT activity levels increased significantly in nude mouse tumours and in foetal and postnatal rat pancreata and also in postnatal liver. At the same time, apparent ACAT activity levels decreased in foetal and regenerating rat livers when compared with respective control tissues. These results suggest that serum cholesterol esters, circulating LCAT and cellular ACAT levels are modulated during cell proliferation.

Animals↗
PubMed1985

Mature and immature synaptosomal membranes have a different lipid composition.

Subfractionation of the optic tectum in chick embryos results in the isolation of two fractions enriched in synaptosomes (fraction A and fraction B). In chicks after hatching, this fractionation results in the isolation of a single synaptosomal fraction (fraction B) and of a fraction enriched in myelin membranes devoid of synaptosomes (fraction A). The lipid composition of synaptosomal fractions (A and B) and corresponding synaptosomal plasma membranes has been analyzed and compared to the lipid composition of similar fractions isolated from 2-3 day-old chicks. The phospholipid composition of fraction A in embryos was mainly represented by phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The PE content was significantly lower than that of PC, which accounted for by approximately 50%. Sphingomyelin (SP) and phosphatidylinositol (PI) accounted for by only 6% of the total membrane phospholipids. Fraction A isolated from the young chicks showed many significant changes. PC accounted for by approximately 40% and PE made up 35%. The amount of phosphatidylserine (PS) and SP increased. These data parallel our previous morphological observations, which showed that fraction A contains immature synaptosomes in embryos but myelin membranes and no synaptosomes in the young chicks. Fraction B has been shown to contain synaptosomes at all stages considered. It possessed in embryos a lipid composition similar to fraction A, except that PC content was higher in young embryos. The analyses on membrane fractions confirmed these results. On the contrary, this fraction showed many significant changes after hatching. The content of PC was significantly reduced, PE/PC ratio was significantly increased as well as ethanolamine plasmalogen (PLE) content. The percentage of PS, PI and SP were increased. The composition of fatty acids of the total fraction of phospholipids was also examined. The results parallel the observations on phospholipid classes.

Age Factors↗
PubMed1984

Changes in serum and hepatic cholesterol in lead-induced liver hyperplasia.

Lead nitrate when injected intravenously as a single dose to male Wistar rats causes a strong hepatic proliferative response followed by reabsorption of excess tissue within 10-14 days. The rate of cell proliferation in this hyperplastic model was positively correlated with hepatic de novo synthesis of cholesterol, stimulation of the hexose monophosphate shunt pathway of glucose metabolism and with alterations in serum lipoproteins.

Animals↗
PubMed1983

[Botulism caused by preserved mushrooms].

We describe two cases of botulism caused by home-prepared under olive oil mushrooms. We stress the importance of an accurate anamnestic study and of the recovery of the toxic material for the diagnosis and therapy. The serological test on patient's blood, the isolation and the identification of botulinic toxin give the possibility to confer a specific character to the serotherapy The prevention of these toxic infections require a wide education on the preparation and storage of foods.

Adult↗
PubMed1978

[Salmonellosis in Cagliari].

The therapy (generally ineffective) and the prophylactic measures of "Salmonellosis" are examined critically during a period of three years, 1974 -- 1976, when a large increase of infection was present in children (without letal cases). The extension of mass-vaccination, particularly by oral treatment with microbic pap of attenuate living (or dead) stock that represent the most significant antigenic groups (4, 9, 3, 6, 7, 8) is suggested.

Adult↗