Biomedical subjects
Publications and source records attributed to A Di Biase.
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Studies were carried out using an isolated rat liver system to define: the contribution of exogenous phosphatidylcholine (PC) to biliary phospholipid secretion; and its hepatic metabolism during perfusion of the livers with conjugated bile salts with different hydrophilic/hydrophobic properties. A tracer dose of sn-1-palmitoyl-sn-2-[14C]linoleoylPC was injected as a bolus into the recirculating liver perfusate, under constant infusion of 0.75 mumol/min of tauroursodeoxycholate or taurodeoxycholate. The effects on bile flow, biliary lipid secretion, 14C disappearance from the perfusate and its appearance in bile, as well as hepatic and biliary biotransformation were determined. With both the bile salts, about 40% of the [14C]PC was taken up by the liver from the perfusate over 100 min. During the same period less than 2% of the given radioactivity was secreted into bile. More than 95% of the 14C recovered in bile was located within the identical injected PC molecular species. The biliary secretion of labeled as well as unlabeled PC, however, was significantly higher in livers perfused with taurodeoxycholate than tauroursodeoxycholate, while the reverse was observed with respect to bile flow and total bile salt secretion. The exogenous PC underwent extensive hepatic metabolization which appeared to be influenced by the type of bile salt perfusing the liver. After 2 h perfusion, the liver radioactivity was found, in decreasing order, in PC, triacylglycerol, phosphatidylethanolamine and diacylglycerol. In addition, the specific activity of triacylglycerol was significantly higher in tauroursodeoxycholate than in taurodeoxycholate-perfused livers (P less than 0.025), while the reverse was true for the specific activity of hepatic PC (P less than 0.01). Because taurodeoxycholate and tauroursodeoxycholate showed opposite effects on both biliary lipid secretion and hepatic PC biotransformations, we conclude that the hepatic metabolism of glycerolipids is influenced by the physiochemical properties of bile salts.
The metabolic fate of exogenous deoxycholate administered either intraperitoneally or intragastrically to male Hartley guinea-pigs was investigated. Two animals received a constant infusion of [24-14C]deoxycholate through an intraperitoneal catheter for 2 hr. Bile was quantitatively collected in 30 min samples during infusion and for 2 additional hours. Each bile sample was analyzed for composition and radioactivity. Five animals received for 15 days, through an intragastric catheter, 35 mg/kg/day of deoxycholate. The biliary bile acid composition was compared with that of a sham-operated control group. The studies with both animal models indicated that guinea-pigs, as the only species so far known, extensively oxidize deoxycholate to form 3-oxo,12 alpha-hydroxy-cholanic acid, which is secreted in bile mostly conjugated with glycine. In addition a small fraction (approx. 7%) of the administered deoxycholate is 7 alpha hydroxylated to form cholic acid. The metabolites being more hydrophilic than administered deoxycholate, it is suggested that guinea-pig liver counteracts the adverse increase in bile acids detergency, which follows deoxycholate administration, by converting most of the latter into less detergent compounds.
Bile salts and phospholipids from bile of chicken, dog, sheep, rat, ox, pig, guinea-pig and man were analyzed by high-performance liquid chromatography. Bile salts showed marked differences in their hydrophilic properties, owing to hydroxyl structure and type of conjugation. Phospholipids were generally similar, containing 90-95% of phosphatidylcholine which was made of molecular species containing palmitic acid in the sn-1 position. The comparative analysis of bile salts and phosphatidylcholines profile demonstrated that bile salts hydrophilicity influences the quantity of phosphatidylcholine in bile but not the quality.
The aim of the present study was to establish whether the oral administration of bile acids with different hydrophilic properties affects the amount of phosphatidylcholine as well as the pattern of PC molecular species secreted in bile. We studied the biliary output of total and individual PC species in cholecystectomized T-tube patients, with a total biliary outflow, after oral administration of 750 mg of ursodeoxycholate (3 patients) or deoxycholate (3 patients). The latter experiments were repeated after 3 days of taurine supplementation (1500 mg daily) in order to increase, by means of the tauro-conjugation, the hydrophilicity of the secreted BA. A linear function was observed, during all the studies, between BA and PC biliary secretion, but the amount of PC secreted per mole of BA was higher for the less hydrophilic BA, such as deoxycholate, than for the more hydrophilic ursodeoxycholate or during deoxycholate plus taurine experiments. With regard to the pattern of PC molecular species, we observed no changes after administration of ursodeoxycholate. An increase in the secretion of the major polyenoic species (i.e., 16:0-18:2 and 16:0-20:4), with respect to the secretion of the monoenoic, was revealed during deoxycholate experiments. Conversely, during the deoxycholate plus taurine experiments, the secretion of the major monoenoic PC species (i.e., 16:0-18:1) increased more than that of the polyenoic species. We suggest that the observed modifications of the pattern of PC molecular species, secreted in bile, represent the result of a physicochemical effect of BA on liver membranes.
The finding of high plasma free fatty acid (FFA) levels in cirrhotic patients has been attributed either to decreased hepatic clearance or to enhanced fat mobilization. To better clarify these hypotheses, total and individual FFA and glycerol levels were determined in 21 cirrhotic patients with different degrees of hepatocellular damage (evaluated by liver function tests), portal hypertension (evaluated by endoscopy and clinical signs), and nutritional status (evaluated by anthropometric and biohumoral parameters) and in 10 age- and sex-matched healthy subjects. Glucose tolerance and insulin and glucagon levels were determined in all individuals. Well-nourished and malnourished patients were identified within the cirrhotic group. Plasma FFA and glycerol concentrations were well correlated (r = 0.47, P less than 0.05), levels being significantly higher in cirrhotic individuals than in controls (746.6 +/- 46.29 SE v 359.22 +/- 40.82 mumol/L, P less than 0.001 for plasma FFA; 150.1 +/- 3.12 v 82.5 +/- 9.2 mumol/L, P less than 0.01 for glycerol). Plasma FFA and glycerol showed no correlation with the liver function test results or portal hypertension parameters. Interestingly, plasma levels of FFA and glycerol were influenced by the nutritional status, significantly higher FFA levels being observed in the well-nourished than in the malnourished patients (842.5 +/- 47.5 v 563.4 +/- 78 mumol/L, P less than 0.005). Furthermore, a positive correlation was found between plasma glycerol level and percentage of triceps skinfold (r = 0.45, P less than 0.05). No correlation was found between plasma levels of FFA or glycerol and glucose tolerance, insulin and glucagon.(ABSTRACT TRUNCATED AT 250 WORDS)
In this paper we propose a novel, rapid and simple high-performance liquid chromatographic (HPLC) method for the identification and quantitation of individual phosphatidylcholine (PC) molecular species from natural mixtures. To overcome difficulties deriving from the lack of adequate standards and from the variability of the responses to UV spectrophotometric detectors currently used in HPLC analysis, we first fractionated and quantitated the major molecular species of a commercial egg PC by means of a preparative column. The identification of PC molecular species was confirmed by gas-liquid chromatographic analysis of fatty acids. We employed the fractions recovered from preparative HPLC to determine the detector calibration factors of the individual molecular species separated using an analytical, high-speed, reversed-phase HPLC column. The proposed method seems to be adequate for the analysis of PC from many biological sources. Its application to the analysis of human hepatic and gallbladder biliary PC is shown.
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The fatty acid composition of biliary phosphatidylcholine was analyzed in 13 patients with radiolucent gallstones undergoing elective cholecystectomy, and in 11 normolipemic patients without gallstone undergoing abdominal surgery. The only difference in the percentage fatty acid composition between the two groups was a significantly (p less than 0.05) higher percentage arachidonic acid in the first group. This acid was exclusively located in the sn-2 position of phosphatidylcholine (PC), accounting for 13.0 +/- 4.9% in the first group and 8.2 +/- 4.9% in the second (p less than 0.05). The percentage arachidonic acid of PC was negatively correlated (p less than 0.001) with the percentage biliary chenodeoxycholate in gallstone patients, but not in controls. Explanation of these findings is, at present, only speculative.
UNLABELLED: Serum and biliary unsulfated bile acids were studied using a gas chromatographic method in 8 patients before and 2 months after portacaval anastomosis. Total serum bile acids were 21.6 +/- 3.6 mumol/liter before and 68.0 +/- 8.6 mumol/liter after surgery (P less than 0.005). Cholic acid rose from 26.5 +/- 3.4% to 33.8 +/- 4.8% (P less than 0.02) of the total serum bile acids, while chenodeoxycholic acid decreased from 67.9 +/- 4.1% to 60.8 +/- 4.3% (P less than 0.05). The relative concentration of cholic and chenodeoxycholic acids in bile increased slightly but not significantly after surgery, while deoxycholate fell from 8.5 +/- 1.7% to 2.1 +/- 0.6%. CONCLUSIONS: (1) in cirrhosis the serum and biliary bile acid composition are markedly different, the cholic-chenodeoxycholic ratio being much lower in serum than in bile; (2) after portacaval anastomosis serum and biliary bile acid patterns tend to become similar; (3) percent biliary deoxycholate decreases significantly after surgery.
Brain development is a sequential anatomical process characterised by specific well-defined stages of growth and maturation. One of the fundamental and necessary events in the normal development of the central nervous system in vertebrates is the formation of a myelin sheath. It is becoming more evident that this process is influenced by dietary lipids. A number of findings have indicated that the administration of a diet deficient in essential fatty acids during development causes hypomyelination in the rat brain. Our studies have shown that lipids can also play a role in accelerating myelinogenesis in the brain of rats whose mothers had been fed, during pregnancy and lactation, a lipid fraction extracted from yeast grown on n-alkanes. Further studies have shown that accelerated myelinogenesis is connected to a precocious appearance of behavioural reflexes. Thus, the use of particular lipids in human nutrition must be carefully screened for possible effects on brain development.
Fifteen patients with a stenosis of the internal carotid artery superior than a 70% were studied in order to analyze the effects of TEA on the ocular hemodynamics. Analysis was made by ophthalmodynamography and electrofunctional studies. An improvement of the ocular hemodynamics was found, particularly by ophthalmodynamography and visual evoked potentials.
The connective tissues of the bovine optic nerve and left recurrent nerve have been investigated at the ultrastructure level by TEM and freeze-fracture. The outermost of three concentric sheaths enveloping the nerve appear very similar; the intermediate sheaths appear different enough to suggest different functionalities, while the innermost sheaths are completely dissimilar. The ultrastructural aspects of the extracellular matrix suggest that all the connective tissues may mainly play a passive role as a packing material for the nerve fibers, while none of the sheaths seems apt to withstand mechanical stresses.
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