No abstract

The incorporation of 14C-labelled pyruvate into glyceride fatty acids and glyceride glycerol has been measured in fat cells prepared from epididymal adipose tissues of normal rats, rats starved for 24 h, rats starved for 24 h and refed a carbohydrate diet for 24 h or rats starved for 24 h and refed a fat diet for 24 h. Rates of fatty acid synthesis were decreased in starved and starved, fat refed cells and increased in starved, carbohydrate refed cells. I n all four dietary states, addition of palmitate to the incubation medium resulted in increased rates of glyceride glycerol formation and decreased rates of fatty acid synthesis from 14C-labelled pyruvate. In normal cells these effects of palmitate were maximal below 1 mM palmitate. Dietary-induced alterations in incorporation of 14C-labelled pyruvate into glyceride glycerol, maximised by addition of palmitate, correlated well with corresponding alterations in the activity of extramitochondrial phosphoenolpyruvate carboxykinase in the cells, but did not correlate with alterations in the activity of pyruvate carboxylase or mitochondrial phosphoenolpyruvate carboxykinase. Use of marker enzymes allowed an assessment to be made of the distribution of these enzymes between extramitochondrial and mitochondrial spaces.The incubated rat epididymal fat pad, using pyruvate as the sole substrate, has been shown to be able to synthesise both the glycerol and fatty acid portions of glycerides [l-51. Isotopic evidence has been presented that the formation of glyceride glycerol from pyruvate proceeds through the carboxylation of pyruvate to oxalacetate, the formation of phosphoenolpyruvate from oxalacetate, and subsequently the production of glycerol phosphate through a partial reversal of glycolysis [6,7]. It has been suggested that this pathway may be important for the maintenance of glyceride turnover in metabolic situations associated with a decreased availability of glucose [6,8,9]. The presence of both pyruvate carboxylase and phosphoenolpyruvate carboxykinase has been demonstrated in both soluble and mitochonEnzymes. Citrate (isocitrate) hydro-lyase or aconitate hydratase (EC 4.2

In Italy, data on aluminium concentration in food items are scarce although aluminium containers are widely used to cook, to freeze or to wrap foods (foil) and it is known that aluminium can migrate from containers to foods. Therefore, an experimental study was carried out to quantify aluminium exposure from ingestion of actual total diets and from migration from containers to foods in conditions representative of the actual use. Samples of 24 h diets were collected, homogenized, lyophilized and the amount of aluminium was determined by atomic absorption spectrometry. The aluminium concentrations ranged from 1.0 to 2.1 mg/kg of food; the intake of aluminium ranged from 2.5 to 6.3 mg/day. The amount of aluminium migrating from aluminium cookware was determined by cooking various representative foods in aluminium and in glass or stainless steel containers. From comparison of the results, the increase in aluminium because of migration from cookware was relatively low, with the highest release into acidic and salty foods. The daily intake of aluminium even if all the foods were prepared and stored in aluminium containers would be approximately 6 mg/day, a very low value compared with the Provisional Tolerable Weekly Intake of 7 mg/kg body weight (equivalent to 60 mg/day for an adult man) established by the Joint FAO/WHO Expert Committee on Food Additives.

Diets high in fish oil containing polyunsaturated fatty acids of the n-3 family, have been suggested to decrease the risk of cardiovascular disease. However these lipids are highly susceptible to oxidative deterioration. In order to investigate the influence of n-3 fatty acids on oxidative status, the effect of feeding rats with fish oil or coconut oil diets was studied by measuring different parameters related to an oxidative free radical challenge. Synthetic diets containing 15% (w/v) fish oil or coconut oil were used to feed growing rats for 4 weeks. As compared to control diet, the fish oil containing diet produced a significant decrease of cholesterol and triglyceride concentration in serum, however there was a significant increase in lipid peroxidation products. In addition, in fish oil fed animals, there was also a decrease in vitamin E and A concentration. Furthermore, the rate of lipid peroxidation in isolated microsomes was three fold higher in rats fed fish oil as compared to rats with coconut oil diet. No significant differences between the two experimental groups were observed in superoxide dismutase (SOD) and phospholipid hydroperoxide glutathione peroxidase (PHGPX) activities. However, there was a decrease in glutathione peroxidase (GPX) activity. These results suggest that fish oil feeding at an amount compatible with human diet, although decreasing plasma lipids, actually challenge the antioxidant defence system, thus increasing the susceptibility of tissues to free radical oxidative damage.

The results indicate that coffee brewed in the Italian way does not alter blood levels of total cholesterol, HDL-cholesterol and LDL-cholesterol, since no significant differences were observed in these blood parameters after a 6-week break from coffee consumption.