Prooxidant-antioxidant equilibrium in rowers: effect of a single dose of vitamin E.

AIM: The purpose of this research was to explain whether a single dose of vitamin E influences on disturbances of pro-oxidant-antioxidant equilibrium induced a laboratory 2,000 m rowing test. METHODS: The athletes were divided into two groups: vitamin E (1.000 mg alfa-tocopherol acetate) and P (placebo: cod-liver oil) supplemented 3 h before exercise. In the subjects' blood levels of following parameters were estimated: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), lipid peroxidation products (TBARS) and protein carbonyls (PC). Creatine kinase (CK) and beta-glucuronidase (betaG) activities were also measured as markers of muscle damage. RESULTS: The applied exercise at maximal intensity (lactate: vitamin E=14.39+/-1.77 mmol/L, P=14.09+/-1.4 mmol/L) caused significant changes in the tested parameters in both groups: SOD (vitamin E Ø30%, P Ø50%), CAT (vitamin 70%, P 12%), GPx (vitamin 49%, P 45%), TBARS (vitamin 70%, P 71%), PC (vitamin 41%, P 78%), CK (vitamin 19%, P 32%), betaG (vitamin 42%, P 47%). The P/A ratio (TBARS/SOD+CAT+GPx) was significantly lower in vitamin E in comparison with placebo, but after 30 min and 24 h restitution it returned to pre-exercise level. Between P/A ratio and PC concentration there was observed positive correlation (P<0.001). No effect of vitamin E on CK and betaG activities were observed. CONCLUSIONS: A single dose of 1,000 mg vitamin E enhances oxidative defense thus attenuates oxidative damage but it is not so much relevant to recommend the antioxidant supplementation by rowers.

Microstructural analysis of bile: relevance to cholesterol gallstone pathogenesis.

The study of physical-chemical factors and pathways leading to cholesterol crystallization in bile has important clinical relevance. The major processes in cholesterol gallstone formation can be subdivided into nucleation, formation and precipitation of solid crystals (crystallization), crystal growth, crystal agglomeration and stone growth. A clear understanding of the microstructural events occurring during the earliest stages of these processes in bile is crucial for the identification of factors possibly delaying or preventing precipitation of cholesterol crystals and, therefore, gallstone formation in bile. Detection and characterization of microstructures in native and model biles can be achieved by both direct and indirect techniques. Direct imaging techniques provide more readily interpretable information, but sample preparation problems, particularly for electron microscopy, are a source of artifacts. Moreover, microscopic techniques provide only qualitative data without the possibility to quantitate or to analyse the composition of microstructures. Several indirect techniques have been used to obtain additional microstructural information about nucleating bile. These techniques have the disadvantage of often being model dependent in addition to constraints specific for each method. The systematic, judicious use of a combination of complementary direct and indirect techniques have led to a comprehensive understanding of the various microstructural processes and interactions occurring during bile secretion, flow in the biliary tract and storage in the gallbladder. This forms the basis for our current understanding of cholesterol nucleation, crystallization and gallstone formation.

The incorporation of fatty acids of different chain length into liver and biliary lipids in the perfused rat liver.

In an attempt to correlate the incorporation of fatty acids (FA) of different chain length into liver and biliary lipids, isolated rat livers were perfused for 2 h with Krebs-Ringer bicarbonate containing 1% albumin and 10 mumol of [1-14C]-labeled FA: C2, C8, C10, C12, C16, and C18:1. One to 1.36 mumol of medium-chain fatty acids (MCFA, C8, C10, and C12) and 6.6 mumol of long-chain FA (LCFA) were incorporated into liver lipids, 40% of the latter into phosphatidylcholine (PC). 14C-acetate (13 nmol) was incorporated into biliary cholesterol; 14C-MCFA contributed only 3.2-5 nmol; LCFA did not lead to newly synthesized cholesterol. Newly synthesized liver PC (2.75 to 3.25%) and newly synthesized liver cholesterol (6.5 to 10%) were secreted into bile. The specific radioactivity of biliary PC after infusion of all-saturated FA was 3.8-6.8 times higher than that of liver PC; for C18:1 it was only 1.7-fold. The specific radioactivity of biliary cholesterol, as compared to liver cholesterol, was 12 times higher for C2 and five times higher for MCFA. This indicates that a considerable proportion of the newly synthesized lipids was secreted into bile prior to significant mixing with preexisting liver PC and cholesterol pools. Liver PC contained 8% of unchanged 14C-C12; while 14C-C10 was not detected. Biliary PC, in contrast, contained 18% of unchanged 14C-C12 and 3% 14C-C10. These results suggest that after prolonged infusion of medium-chain triacylglycerols/long-chain triacylglycerols to patients, biliary PC may become enriched with MCTA. In addition, the oxidation of these FA may provide C-2 units which increase cholesterol synthesis.

Biosynthesis of medium-chain triacylglycerols and phospholipids by HepG-2 cells.

In an attempt to understand the metabolism by the liver of fatty acids (FA) of different chain length, we have studied the incorporation of [1(-14)C]-labeled C2, C8, C10, C12, and C16 into cellular lipids by HepG-2 cells. Over 90% of the radiolabeled FA were detected in phospholipids (PL) and triacylglycerols (TAG). The incorporation of C12 and C16 was three to four times higher than that of C8 and C10 (and reached 35 nmoles per mg protein after 1.5 h). The radioactivity of C2, C8, and C10 was recovered mainly in PL. C12 and C16 were incorporated at approximately equal amounts into PL and TAG. The radioactivity of both C2 and C8 was recovered exclusively in long-chain FA, suggesting oxidation of C8 into C2 units prior to FA synthesis. C10 likewise yielded mainly long-chain FA. However 10% of unchanged C10 was found in PL and up to 30% in TAG. 14C-C12 was largely incorporated unchanged. Under these conditions, the presence of C10 and C12 in PL and TAG was shown also by gas-liquid chromatography. In the presence of either C2, C8, or C10, up to 30% of 14C-monounsaturated FA were detected in PL and TAG. With C12 and C16, the fraction of 14C-monounsaturated FA was much smaller suggesting that extensive desaturation occurred during de novo synthesis.

The effects of dietary phospholipids enriched with phosphatidylethanolamine on bile and red cell membrane lipids in humans.

The role of phospholipids in biliary cholesterol solubilization and crystallization has only recently begun to be appreciated. Phospholipid vesicles are believed to be the metastable carrier from which cholesterol nucleates. Cholesterol crystallization is influenced by the phospholipid species in bile. Feeding rats and hamsters with diets enriched in phospholipids or their precursors, especially ethanolamine, resulted in reduced cholesterol saturation of bile. Although whole phospholipids are normal dietary constituents, the effects and safety of phospholipid components have not been tested in humans. In the present study, we have evaluated the effects of a dietary phospholipid mixture, enriched with phosphatidylethanolamine, on human bile and red blood cell membrane lipid composition. Five ambulatory volunteers having a chronic indwelling T-tube, with an intact enterohepatic circulation, were investigated. Thirty-six grams of phospholipids (54% phosphatidylethanolamine, 54% linoleyl acyl chains) were added to their daily diet for fourteen days. Biliary nucleation time, cholesterol carriers, as well as plasma, red blood cell membrane, and bile lipid compositions, were monitored. Following phospholipid supplementation, the proportion of linoleyl chains (18:2) in biliary phospholipids increased significantly from 31.1 +/- 1.2 to 37.7 +/- 5.3%, while that of oleyl chains (18:1) decreased from 11.4 +/- 1.6 to 9.6 +/- 1.1%. These changes were accompanied by an increase of linoleate and its metabolite, arachidonate, in red cell membranes. Phospholipid feeding did not cause any side effects, and no significant changes in biliary nucleation time, cholesterol, phospholipid, or bile salt concentrations, or in the distribution of cholesterol within micelles or vesicles. We conclude that phospholipid feeding is safe, and can be effective as a vehicle for lecithin fatty acyl chain modulation of bile and lipid membranes. These findings may provide a basis for a controlled modulation of biliary phospholipids to increase cholesterol solubility in bile.

Cellular sites for the competence-provoking factor of streptococci.

Immune globulins against competent cells of group H streptococci, strains Challis and Wicky, inhibited genetic transformation to streptomycin resistance when added to competent cultures. Antibodies against noncompetent cells did not inhibit transformation of competent cells. Strain Challis is spontaneously highly transformable. Strain Wicky is very poorly transformable but can be converted to high transformability with the exocellular competence-provoking factor (CPF) produced by strain Challis. Globulins against noncompetent cells of strain Challis and Wicky also inhibited transformation when added to noncompetent cultures prior to conversion to competence. Antibodies against cells of the related strain Blackburn, however, did not inhibit transformation under any circumstances. It is concluded that, although globulins prepared against competent cells block the deoxyribonucleic acid receptor sites present in these cells, the globulins prepared against noncompetent cells prevent conversion to competence by blocking the access of CPF to specific cellular sites for this factor. Strain Blackburn seems not to contain CPF-receptive sites and is, therefore, nontransformable.

A new continuous biofilm bioreactor for immobilized oil-degrading filamentous fungi.

A new type of horizontal biofilm bioreactor for continuous bioconversion of emulsified oily substrate by immobilized growing biofilm of filamentous fungi was designed, constructed, and feasibility tested. The new reactor design provides "self"-immobilization of homogenized mycelium leading to even biofilm development. This was accomplished by using stainless steel screens of optimal mesh, mounted in parallel and stretching outward from a main rotating axis of a biological rotating contractor. Each screen was equipped with a pair of stainless steel blades mounted on supports allowing for continuous biofilm "shaving" beyond a predetermined thickness, thus retaining freshly growing active biofilm surface. The feasibility of the new bioreactor was demonstrated by decalactone production from emulsified castor oil by immobilized filamentous fungi (Tyromyces sambuceus). The combination of oriented metal screens and moving blades was found to be highly effective for a model system in maintaining stable substrate emulsion in the reactor in either batchwise or continuous processing, as well as maintaining biofilm thickness with continuous removal of excess growing hyphae.

Polymorphism of indomethacin. Part II. Identification and rapid determination of polymorphic forms of indomethacin by IR spectrometry.

A procedure is described, which make it possible to determine the content of individual polymorphic forms of indomethacin in their mixture by IR spectrometry. IR spectra recorded in the range of 1600--1800 cm-1 have been used in the determinations. The method is especially useful for analytical control of the technological process of preparing the most pharmacologically active-gemma-form of indomethacin.

Polymorphism of indomethacin. Part I. Preparation of polymorphic forms of indomethacin.

Technologically useful methods of preparing defined polymorphic forms of indomethacin (especially gemma-form) have been described. The influence of various crystallization parameters on the formation of individual form of indomethacin have been discussed.

Management of gallstone ileus--a controversial issue.

Four cases of gallstone ileus were treated during a 3-year period. Three patients aged 74-81 years underwent a one-stage operation consisting of enterotomy, stone extraction, cholecystectomy, and suturing of the entero-biliary fistula. One 83-year-old patient was considered a poor risk and underwent only enterotomy with stone extraction, without cholecystectomy. In all four patients the postoperative course was uneventful. In one, carcinoma of the gallbladder was found. On the basis of this experience as well as that reported in the literature, it is concluded that the procedure to be preferred in stabilized patients is a one-stage operation, whereas in debilitated patients only relief of the obstruction should be sought.

Effect of three intravenously administered fat emulsions containing different concentrations of fatty acids on the plasma fatty acid composition of premature infants.

The effects of an intravenously administered lipid emulsion supplemented with gamma-linolenic acid on the fatty acid profile of premature infants were compared with those of two conventional lipid emulsions. Fifty-nine premature neonates receiving total parenteral nutrition were randomly assigned to receive either fat emulsion containing gamma-linolenic acid and long-chain triglycerides (LCT), an LCT emulsion, or a 50% (wt/wt) mixture of medium-chain triglycerides and LCT emulsion. Forty-nine infants completed the study. During the 6-day study there was a significant tenfold increase in the plasma levels of gamma-linoleic acid in the supplemented group versus the other two groups. A significant threefold to fivefold increase in the omega 6 long-chain polyunsaturated fatty acids was observed in all groups. These changes seemed to be attributable mostly to linoleic acid from the lipid emulsion, despite the 50% lower dose in the medium- and long-chain triglycerides group. The increase in the omega 3 long-chain polyunsaturated fatty acids also was mainly caused by a similar increase in the level of alpha-linolenic acid. No differences were recorded in the linoleic/alpha-linolenic acid ratio among the groups. Plasma levels of some of the semiessential fatty acids were significantly higher in the medium- and long-chain triglycerides group than in the LCT group. This may be related to slower elimination of LCT, to the difference between emulsions, or to less substrate inhibition on delta-6-desaturase, which seems to be less of a rate-limiting enzyme than previously considered. Further intravenous feeding trials are needed to identify the optimal balance of fatty acids for nutrition of these premature infants.

Does lipid infusion affect bile composition in humans?

A prospective study was performed to investigate the effect of short-term lipid infusion on bile composition and its lithogenicity in humans. The study group comprised 44 patients scheduled for laparotomy. The patients were hospitalized 48 h prior to elective surgery and randomized to be infused with a lipid emulsion of either long chain triglycerides (LCT) or a mixture of medium and long chain triglycerides (MCT/LCT) for 6 h of each 24 h, or with glucose-saline. Bile samples were obtained by puncture of the gallbladder during operation. In non-gallstone patients, both lipids caused an elevation of biliary cholesterol and phospholipids, but this effect was more pronounced and significant (P <0.001) only with the mixture of MCT/LCT emulsion. The fatty acid composition of biliary phospholipids was not affected by either lipid infusion. The Cholesterol Saturation Index increased significantly (P <0.005) with the MCT/LCT emulsion and there was insignificant shortening in the nucleation time. In contrast to patients with cholelithiasis, no effects could be demonstrated on gallbladder bile composition, cholesterol saturation index, nucleation time, or fatty acid composition of phospholipids. The effects of both lipid emulsions on plasma lipids and lipoproteins were similar in all groups. Our results indicate that lipid emulsions containing MCT/LCT induce lithogenic changes in the composition of human bile. We propose that the lack of effect of lipid infusion on bile composition in patients with cholelithiasis may be due to precipitation of excess cholesterol in the gallbladder of cholesterol gallstone patients whose bile is already saturated. These findings imply that patients with cholesterol gallstones cannot be grouped with non-gallstone patients in studies of alterations of bile composition.

Are bilirubin and plasma lipid profiles of premature infants dependent on the lipid emulsion infused?

The effect of a lipid emulsion containing long-chain triglycerides (LCT) and supplemented with L-carnitine on plasma lipids and bilirubin in premature neonates on total parenteral nutrition was compared to that of lipid emulsions containing either LCT or a mixture of LCT and medium-chain triglycerides (MCT). In a double-blind randomized study 49 premature neonates received one of the three fat emulsions, given intravenously, over 16-20 h daily for 6 days. Plasma carnitine levels increased significantly in the supplemented group only; the addition of carnitine did not seem to affect any of the parameters studied. Mean plasma triglycerides rose by 193 and 199% in the carnitine-supplemented and the LCT groups, respectively, and by 314% in the MCT/LCT group. On the sixth day of the study free fatty acids were significantly higher in the MCT/LCT group than in the other two groups. Plasma phospholipids and free cholesterol increased (p < 0.05) progressively in all groups and were correlated (r = 0.74, p < 0.001). At the end of the 6-day study all groups showed a similar decline in free and total bilirubin levels despite the significant increase in plasma lipids and free fatty acids resulting from the stepwise increase in lipid load. No correlation was found between free fatty acids and free bilirubin. Since hyperbilirubinemia and hypertriglyceridemia appear to be clinically independent factors, the infusion of lipids should not be withheld from jaundiced infants on total parenteral nutrition.

The effects of short term lipid infusion on plasma and hepatic bile lipids in humans.

BACKGROUND: Patients on parenteral nutrition have an increased incidence of gall bladder sludge and gallstone disease, thought to be related to bile stasis. Intravenous lipid emulsions, especially those containing medium chain triglycerides, have also been shown to have a lithogenic effect on the composition of bile in the gall bladder. AIMS: To determine whether lipid infusion influences hepatic bile composition in patients with an indwelling T tube following cholecystectomy and choledochotomy. METHODS: In eight patients undergoing the above surgical procedure, the time at which effects of the interrupted enterohepatic circulation were minimal was determined. Twenty two cholesterol gallstone patients with bile fistula were then randomised to receive an infusion of a lipid emulsion containing either long chain triglycerides or a mixture of long and medium chain triglycerides. RESULTS: Lipid infusion resulted in a significant increase in plasma levels of triglycerides and phospholipids. Both lipid emulsions caused an increase in hepatic biliary cholesterol level and cholesterol saturation index, but this effect was more pronounced with medium chain triglycerides. The fatty acid composition of biliary phospholipids showed a significant enrichment of linoleic acid by both lipid infusions. CONCLUSIONS: Infusion of triglycerides causes lithogenic changes in hepatic bile composition in humans, the lithogenic effect of infusion of medium chain triglycerides being more pronounced than that of long chain triglycerides. This effect, coupled with gall bladder stasis, may be responsible for the increased risk of biliary sludge and gallstone formation in patients on long term lipid infusion.