Resveratrol inhibits fatty acid and triacylglycerol synthesis in rat hepatocytes.

BACKGROUND: The putative role of resveratrol, a polyphenol present in grapes and other plants, in modulating dislypidemia, thus preventing cardiovascular diseases, is generally based on proliferating cell lines and in vivo studies in different pathological conditions. The aim of the present study was to investigate whether resveratrol plays a role on lipid biosynthesis in rat hepatocytes. MATERIALS AND METHODS: The effect of resveratrol on total rate of fatty acid, cholesterol and complex lipid synthesis, assayed by the incorporation of [1-(14)C]acetate into these lipid fractions, was investigated in rat hepatocyte suspensions. Enzyme activities of acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) as well as 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA-R), pace-setting steps of de novo fatty acid and cholesterol synthesis, respectively, were in situ measured in digitonin-permeabilized hepatocytes. RESULTS: Resveratrol-treated hepatocytes exhibited a short-term (30 min) inhibition (IC(50) approximately 25 microm) of total fatty acid synthesis from [1-(14)C]acetate. Among neosynthesized fatty acids, palmitic acid formation was mainly reduced, thus suggesting that enzymatic step(s) of de novo fatty acid synthesis was affected by resveratrol. In digitonin-permeabilized hepatocytes, only ACC activity was noticeably reduced, while no change in FAS activity was observed. A noticeable resveratrol-induced reduction of label incorporation into triacylglycerols was also detected. Conversely, cholesterol synthesis and HMG-CoA-R activity were unaffected by resveratrol. CONCLUSION: Results here reported show that in isolated hepatocytes from normal rats a resveratrol-induced short-term inhibition of fatty acid and triacylglycerol synthesis occurs. This finding may represent a potential mechanism contributing to the reported hypolipidemic effect of resveratrol.

Quercetin inhibits fatty acid and triacylglycerol synthesis in rat-liver cells.

BACKGROUND: Quercetin plays a cardiovascular protective role because of its antioxidant capacity and ability to modulate dyslipidemia. As alterations in hepatic lipid synthesis are crucial to the regulation of serum lipid levels, we investigated the quercetin effect on lipogenesis in rat liver cells. MATERIALS AND METHODS: The effect of quercetin on the rate of synthesis of fatty acids, cholesterol, neutral lipids, phospholipids and very-low-density lipoproteins (VLDL) was investigated in rat hepatocyte suspensions following [1-(14)C]acetate incorporation into these lipid fractions. Enzyme activities of acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) as well as diacylglycerol acyltransferase (DGAT) and 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA-R), pace-setting steps of de novo fatty acid, triacylglycerol (TAG) and cholesterol synthesis respectively were assayed in digitonin-permeabilized hepatocytes. RESULTS: Within 30 min of quercetin addition to the hepatocytes, inhibition (IC50 approximately 25 microM) of fatty acid synthesis occurred. A reduction in label incorporation mainly into TAG was observed. Among neosynthesized fatty acids, palmitic acid formation was greatly reduced, suggesting that enzymatic step(s) of de novo fatty synthesis was affected. Only ACC activity was noticeably reduced, but no change in FAS activity was observed. DGAT activity was also inhibited. The decreased intracellular TAG content was paralleled by a reduction in acetate incorporation into VLDL-TAG. Conversely, cholesterol synthesis and HMG-CoA-R were not significantly affected by quercetin. CONCLUSIONS: In hepatocytes from normal rats, the quercetin-induced decrease in both de novo fatty acid and TAG synthesis, with a consequent reduction in VLDL-TAG formation, may represent a potential mechanism contributing to the reported hypotriacylglycerolemic effect of quercetin.

Changes in lipid composition and lipogenic enzyme activities in liver of lambs fed omega-6 polyunsaturated fatty acids.

Twenty-four lambs (Ovis aries) were used in a 45-day finishing study to evaluate the effects of feeding diets high in linoleic acid (C(18:2), omega-6) on liver lipid composition and on lipogenic enzyme activities in subcellular fractions of liver. Lambs were fed either a 5% safflower oil (SO, high linoleic acid) supplemented diet or a control diet without added oil. SO feeding caused a reduction in the amount of serum and liver triacylglycerols and cholesterol, whereas the level of phospholipids in both tissues was hardly affected. In liver of SO-treated lambs an increase in the levels of C(18:2) and arachidonic acid (C(20:4), omega-6), together with a simultaneous decrease of saturated fatty acids, was observed. In comparison to rat liver, rather low activities of enzymes in the pathway for de novo fatty acid synthesis, i.e. acetyl-CoA carboxylase and fatty acid synthase, were found in lamb-liver cytosol. Both enzyme activities, as well as those of the NADPH-furnishing enzymes, were significantly reduced by SO feeding. In contrast, microsomal and especially mitochondrial fatty acid chain elongation activity, the latter being much higher than that of rat liver, were significantly increased in SO-treated lambs. In these animals, a stimulation of triangle up(9)-desaturase activity was observed in liver microsomes.

Traumas of the middle skull base with TMJ involvement. Case report.

The authors report their experience with temporomandibular joint (TMJ) traumas involving breakage of the roof of the glenoid cavity, an infrequent event that occurs in those cases in which, as a result of the condylar neck not fracturing, the traumatic energy is transmitted to the middle skull base. As the literature contains no valid series for establishing standardized protocols for the treatment of these fractures, we propose our own orthopedic-functional approach. The patient observed by us had suffered a cranio-facial trauma and presented the classical symptoms and signs of TMJ traumas and complete bilateral Bell paralysis. He was subjected to a CAT scan and then to 2-stage treatment consisting of functional rest with liquid diet followed by physiotherapy. An almost total recovery in TMJ function was observed after 1 month. At 1-year follow-up the facial paralysis had resolved completely. On the basis of our experience, breakages of the glenoid cavity can be compared, in terms of treatment procedure, to intracapsular fractures of the TMJ with surgery confined to cases of ankylosis sequelae. To avoid the onset of ankylosis careful control of clinical, functional and radiological follow-up is required.

Effect of starvation on the activity of the mitochondrial tricarboxylate carrier.

The effect of starvation on the activity of the tricarboxylate carrier has been investigated in intact rat liver mitochondria and in a reconstituted system. In both experimental conditions, the rate of citrate transport, when compared to control, is greatly reduced (35-40%) in starved rats. Similar behaviour is shown by the cytosolic lipogenic enzymes. Kinetic analysis of the carrier activity in intact mitochondria and in the proteoliposomal system has showed that during starvation only the Vmax of this process decreases while there is no change in the Km. No difference in the Arrhenius plot and in the lipid composition has been detected, which indicates that the reduced transport activity in fasted animals is not due to a change in the carrier lipid microenvironment. In starved rats, a reduction of the carrier activity has occurred even after the addition of increasing cardiolipin concentrations to proteoliposomes. These findings thus suggest that starvation-induced decrease of citrate carrier activity could be due to a change of the intrinsic properties of the transport protein.

Characterization of pore-forming activity in liver mitochondria from Anguilla anguilla. Two porins in mitochondria?

A fast purification procedure for the isolation and purification of eukaryotic porin (De Pinto et al., (1987) Biochim. Biophys. Acta 905, 499-502) was applied to liver mitochondria of the fish Anguilla anguilla. A protein preparation was obtained which formed slightly anionically selective pores in reconstitution experiments with lipid bilayer membranes. The distribution of single-channel conductances had two maxima of 2.4 nS and 4.0 nS in 1 M KCl. Sodium dodecylsulfate electrophoretograms of the protein preparation showed the presence of two bands of very similar electrophoretic mobility (32 and 32.5 kDa). Both bands cross-reacted with antibodies raised against purified bovine heart porin and with antibodies raised against the 19 amino acids N-terminal end of human porin. No cross-reactivity was observed with antibodies against yeast porin. The peptide maps of the two bands showed slight differences. The possibility of the presence of two different porins in liver mitochondria of Anguilla anguilla is discussed. An extensive immunological comparison of different mitochondrial porins is presented.

Effect of hyperthyroidism on lipogenesis in brown adipose tissue of young rats.

Fatty acid synthetic capacity, investigated both in subcellular fractions and in vivo, is very active in brown adipose tissue of room temperature-acclimated rats. In hyperthyroid animals this tissue, analogously to the liver, exhibits an increased activity of acetyl-CoA carboxylase, fatty acid synthetase and microsomal fatty acid chain elongation, this last mechanism remaining unaffected in mitochondria. An enhancement of reducing capacities of a group of cytoplasmic NADP-dependent enzymes has also been observed in brown adipose tissue of hyperthyroid rats, probably due to a greater use of NADPH in lipogenesis under these conditions. An increase in palmitate oxidation and in polyenoic fatty acids was observed in mitochondria of brown adipose tissue from hyperthyroid animals. The latter increase is related to the importance of these compounds in the regulation of membrane fluidity and probably to an increased resistance to cold in the hyperthyroid state.

Citrate carrier activity and cardiolipin level in eel (Anguilla anguilla) liver mitochondria.

The activity of the tricarboxylate (citrate) carrier has been assayed in intact liver mitochondria from yellow eel (Anguilla anguilla) and compared to that from rat. The eel-citrate carrier specific activity was approximately 1.7-fold higher than that assayed in rat-liver mitochondria. The content of the main mitochondrial phospholipids, phosphatidylethanolamine and phosphatidylcholine, did not show a significant difference between the two species, while in eel a higher cardiolipin level was observed. Fatty acid composition of eel-liver mitochondrial phospholipids was characterised by a large amount of unsaturated fatty acids, dominated by octadecaenoic acid (C(18:1) (n-9)) and docosahexaenoic acid (C(22:6) (n-3)). The cardiolipin fatty acid pattern of eel-liver mitochondria showed, with respect to the rat, a higher C(20:5) (n-3) and C(22:6) (n-3) content and a lower amount of C(18:2) (n-6) and C(20:4) (n-6). A noticeable activity of lipogenic enzymes was also detected in eel liver cytosol. The results of this study suggest that the remarkable activity of the citrate carrier in eel-liver mitochondria can most likely be ascribed to a considerable cardiolipin level. A covariance of citrate carrier and lipogenic enzyme activities was observed.

Fatty acid chain elongation synthesis in eel (Anguilla anguilla) liver mitochondria.

The properties of fatty acid chain elongation synthesis have been investigated in liver mitochondria of the European eel (Anguilla anguilla). The incorporation of [1-(14)C]acetyl-CoA into fatty acids shows a specific activity of 0.43+/-0.05 nmol/min x mg protein (n=6), which is more than twice higher than that previously reported in rat liver mitochondria. Label incorporation into fatty acids was, in mitochondria disrupted by freezing and thawing, much higher than in intact organelles thus suggesting a probable localization of this pathway inside mitochondria. Only a negligible acetyl-CoA incorporation into fatty acids occurs in the absence of ATP, Mg2+ or reduced pyridine nucleotides; NADH alone seems to be as effective as NADH + NADPH as a hydrogen donor for the reducing steps. CoASH, without effect up to 10 microM, showed a strong inhibition at higher concentrations. From the ratio of total radioactivity and radioactivity in carboxyl carbon it can be inferred that in eel-liver mitochondria only chain elongation of preexisting fatty acids occurs. A significant fatty acid chain elongation activity is also present when, instead of acetyl-CoA, [2-(14)C]malonyl-CoA is used as a carbon unit donor. Moreover, the synthesized fatty acids were actively incorporated into phopholipids, mainly phosphatidylcholine, phosphatidylethanolamine and sphyngomyelin.

Effect of hypothyroidism on the lipid composition of rat plasma and erythrocyte membranes.

The effect of hypothyroidism on plasma and erythrocyte membrane lipid components has been investigated. This pathological state is accompanied by a) a cholesterol increase of about 60% in plasma, and at the same time a 22% reduction in erythrocyte membranes; b) 44% and 30% phospholipid level decreases in both plasma and red cell membranes, respectively; and c) almost unaffected phospholipid and fatty acid compositions of both plasma and erythrocyte membranes. All changes were corrected by treatment of the hypothyroid rats with triiodothyronine for two days. These findings suggest that in hypothyroid rats a reduced transfer of cholesterol from plasma to erythrocyte membrane probably takes place. This could explain, at least in part, the increased hematic cholesterol level observed in hypothyroid animals. In red cell membranes, the simultaneous decrease in cholesterol and phospholipid levels does not alter the cholesterol/phospholipid molar ratio, thus avoiding their abnormal function.

Lipid composition of liver mitochondria and microsomes in hyperthyroid rats.

Triiodothyronine-induced alteration of the lipid pattern in rat-liver mitochondria and microsomes has been investigated. In mitochondria, a 25% total cholesterol decrease and a 14% phospholipid increase have been detected. In these hyperthyroid rat liver organelles, a strong decrease in the total cholesterol/phospholipid molar ratio occurs. On the contrary, in microsomes from the same animals, a decrease of about 23% has been measured for both total cholesterol and phospholipids; hence, in this fraction, the total cholesterol/phospholipid molar ratio is unaffected by hyperthyroidism. The liver mitochondrial phospholipid composition, unlike the microsomal composition, is altered significantly in hyperthyroid rats; a 7.4% phosphatidylcholine decrease is accompanied by a similar additive percentage increase of both phosphatidylethanolamine and cardiolipin. In regard to total phospholipid fatty acid composition in liver microsomes from hyperthyroid rats, no variation has been observed compared with the control rats, whereas in mitochondria from the same animals, a meaningful linoleic acid decrease with a similar arachidonic acid increase has been found. In addition to fatty acid alteration, the separated mitochondrial phospholipid classes also exhibit some increase in stearic acid. Among phospholipids, cardiolipin changes the most of the esterified fatty acids in hyperthyroid rat liver. In this compound, a strong increase in the percentage of both palmitic and stearic acid and a 32.4% decrease of linoleic acid have been found.

Change in cholesterol levels and in lipid fatty acid composition in safflower oil fed lambs.

The influence of safflower oil supplemented (5%) diet both on cholesterol level and on lipid fatty acid composition was investigated in serum, liver and muscle (Longissimus dorsi) of lambs. The fatty acid pattern varied similarly in all the three tissues. An increase in linoleic acid and in some other polyunsaturated fatty acids, and a simultaneous reduction of the saturated fatty acids (mostly palmitic and stearic acid) were observed. On the contrary, cholesterol content decreased notably (44%) in the liver, with a much less evident decrease in serum and muscle of treated animals.

Abnormalities of canines eruption.

The aim of this article is to present the personal experience on the treatment of 2 groups of patients presenting the same problem: the recovery of teeth 13 and 23 in the dental arch. The 1(st) group consists of adult patients aged approximately 20-28 years with a retained position of the permanent canines and permanence of the respective deciduous teeth in the dental arch. In the 2(nd) group, the loss of the deciduous teeth had not been followed by the physiological eruption of the permanent teeth. The authors' aim is to demonstrate that similar orthodontic treatments can represent valid solutions for the treatment of pathologies with different etiopathogenesis.

[Skull base fractures with TMJ involvement: literary review and case report]. / Fratture della base cranica con interessamento dell'ATM: review della letteratura e presentazione di un caso clinico.

The authors report their experience in the treatment of middle skull base fractures with TMJ involvement of ten patients affected by fractures of the glenoid cavity and of the petrous part of the temporal bone, with TMJ disfunction and facial nerve palsy. The treatment has been based on functional rest, a liquid diet for 5 days and than a functional physiotherapy aimed at rehabilitation of the TMJ. The efficacy of treatment has been showed after 2 months by restoring the dental occlusion and the TMJ's function in nine out of ten cases. Three out of four patients (75%) at the same control showed a full resolution of the facial nerve palsy. At an eighth month's follow-up all the cases had a complete resolution of the symptoms. Finally no significant studies have been reported in literature to set standardized protocols for the treatment of glenoid cavity fractures. According to the experience of authors the fractures of the medium cranial base involving the glenoid cavity should be treated as the current trends of intracapsular TMJ fractures. The orthopedic-functional treatment turns out particularly efficacious when there isn't a reduction of mandibular vertical heights.