Lithocholic acid-cholesterol interactions in rat liver plasma membrane fractions.

This study was designed to elucidate the steps involved in the incorporation of lithocholic acid and the increase in cholesterol in liver plasma membranes after lithocholic acid injection. In vitro, cholesterol incorporation or binding to liver plasma membrane fractions enriched in bile canalicular structures occurred only when cholesterol was added simultaneously with lithocholic acid. The addition of cholic acid did not prevent the incorporation or binding of lithocholic acid and of cholesterol. However, when cholic acid was incubated with membranes already containing lithocholic acid and cholesterol, the ratio of cholesterol to lithocholic acid increased from 2 to more than 3 via a reduction of lithocholic acid. The binding of lithocholic acid and cholesterol to membranes rose 5-fold in the presence of cytosolic proteins. By electron microscopy the canalicular membrane structures with a high cholesterol content exhibited few microvilli, and their lumen appeared to have collapsed. These data suggest that simultaneous interaction of lithocholic acid and cholesterol, and not prior incorporation or binding of lithocholic acid to the membrane, may be a prerequisite to cholesterol accumulation in the membrane.

The potential of the hydrocarbon breath test as a measure of lipid peroxidation.

The straight chain aliphatic hydrocarbons ethane and pentane have been advocated as noninvasive markers of free-radical induced lipid peroxidation in humans. In in vitro studies, the evolution of ethane and pentane as end products of n-3 and n-6 polyunsaturated fatty acids, respectively, correlates very well with other markers of lipid peroxidation and even seems to be the most sensitive test available. In laboratory animals the use of both hydrocarbons as in vivo markers of lipid peroxidation has been validated extensively. Although there are other possible sources of hydrocarbons in the body, such as protein oxidation and colonic bacterial metabolism, these apparently are of limited importance and do not interfere with the interpretation of the hydrocarbon breath test. The production of hydrocarbons relative to that of other end products of lipid peroxidation depends on variables that are difficult to control, such as the local availability of iron(II) ions and dioxygen. In addition, hydrocarbons are metabolized in the body, which especially influences the excretion of pentane. Because of the extremely low concentrations of ethane and pentane in human breath, which often are not significantly higher than those in ambient air, the hydrocarbon breath test requires a flawless technique regarding such factors as: (1) the preparation of the subject with hydrocarbon-free air to wash out ambient air hydrocarbons from the lungs, (2) the avoidance of ambient air contamination of the breath sample by using appropriate materials for sampling and storing, and (3) the procedures used to concentrate and filter the samples prior to gas chromatographic determination. For the gas chromatographic separation of hydrocarbons, open tubular capillary columns are preferred because of their high resolution capacity. Only in those settings where expired hydrocarbon levels are substantially higher than ambient air levels might washout prove to be unnecessary, at least in adults. Although many investigators have concentrated on one marker, it seems preferable to measure both ethane and pentane concurrently. The results of the hydrocarbon breath test are not influenced by prior food consumption, but both vitamin E and beta-carotene supplementation decrease hydrocarbon excretion. Nevertheless, the long-term use of a diet high in polyunsaturated fatty acids, such as in parenteral nutrition regimens, may result in increased hydrocarbon exhalation. Hydrocarbon excretion slightly increases with increasing age. Short-term increases follow physical and intellectual stress and exposure to hyperbaric dioxygen.(ABSTRACT TRUNCATED AT 400 WORDS)

Storage of medium-chain triglycerides in adipose tissue of orally fed infants.

The effect of the fatty acid content of the diet on that of adipose tissue was studied in 5 newborn infants studied prior to feeding and 30 infants fed ad libitum from birth with either human milk or a commercial formula as the sole nutrient. Significant positive linear correlations of dietary intake on adipose tissue content of fatty acids were found for both long- and medium-chain fatty acids (MCFA). Infants stored up to 12% of MCFAs in their subcutaneous fat. The technique of direct transesterification improved the recovery of the volatile MCFAs and could explain the finding that medium-chain triglyceride storage in adipose tissue is more extensive than in previous reports. This study documents that MCFAs are not used solely as a source of energy: they can be reesterified or serve for chain elongation, before being deposited in fat stores.

Taurine prevents cholestasis induced by lithocholic acid sulfate in guinea pigs.

The hypothesis that the amino acid used for the conjugation of sulfolithocholate (S-LCA) is a critical determinant of its cholestatic potential was tested in the guinea pig which conjugates 90% of its bile acids with glycine. Twelve groups of animals were used to study the effect of taurine feeding at a concentration of 0.5% in the drinking water for periods of 1, 3, and 5 days before an iv injection of 18 mumol/100 g body weight of S-LCA. Bile flow was monitored in 30-min aliquots over a 3-h period and the bile acid secretion as well as the glycine/taurine ratio of conjugated bile acids were determined. At the end of the various time periods, the livers were examined by light and electron microscopy. Within 3 days after taurine administration there was an increase in bile flow and a reversal of the glycine/taurine ratio with taurine conjugates becoming predominant. Liver morphology was unchanged except for a slight accumulation of lipids after 5 days of taurine feeding. In animals who were not pretreated with taurine, S-LCA injection led to a progressive decrease in bile flow such, that it was reduced to less than 20% at the end of the 3-h collection. S-LCA was conjugated almost exclusively with glycine. In contrast, in the groups fed taurine for 1, 3, and 5 days before the S-LCA injection, bile flow was comparable to that of the groups fed taurine alone. The S-LCA recovered in bile was to a large extent conjugated with taurine. S-LCA animals pretreated with taurine did not exhibit any liver cell changes while the group which had not received taurine before the S-LCA injection showed numerous cytoplasmic vacuoles with normal bile canaliculi. These data show that increasing the availability of taurine through dietary means may exert a protective effect against cholestasis induced by monohydroxy bile acids.

Supplementation with carotenoids corrects increased lipid peroxidation in children with cystic fibrosis.

Evidence of lipid peroxidation previously documented in cystic fibrosis (CF) implies an imbalance between free radical generation and antioxidant defense mechanisms. The aim of the present study was to examine the relation between plasma concentrations of malondialdehyde, a marker of lipid peroxidation, and the exogenous antioxidant line of defense. Malondialdehyde concentrations (90.2 +/- 4.7 nmol/L) in 25 children with CF aged 9.6 +/- 0.8 y were higher (P < 0.001) than concentrations (69.1 +/- 2.6 nmol/L) in 17 children used as control subjects and were not correlated with any marker of disease severity. In contrast with their all-rac-alpha-tocopherol status, which was normal as a result of routine supplementation with a 200-mg dose of all-rac-alpha-tocopheryl acetate/d, beta-carotene was very low. A 2-mo open trial in which 12 children with CF aged 11.5 +/- 0.8 y were given 4.42 mg (8.23 mumol) beta-carotene three times per day led to normalization of the malondialdehyde concentration in all but 1 patient, in conjunction with an increase of plasma beta-carotene from 0.08 +/- 0.03 to 3.99 +/- 0.92 mumol/L. Their plasma concentrations were inversely correlated (r = -0.54, P = 0.006) [corrected] with malondialdehyde when the values measured pre- and posttreatment were pooled. We conclude that beta-carotene deficiency contributes to lipid peroxidation in CF and that supplementation may eventually prove to be a useful adjunct for the management of the disease.

The composition of preterm milk in relation to the degree of prematurity.

Fifty-one samples of 24-h milk collections obtained during the 1st month of lactation from mothers who delivered after gestations of 26 to 31 wk (VPT) contained higher concentrations of nitrogen (297 +/- 11 mg/dl), total fatty acids (4.46 +/- 0.17 g/dl), percentage medium chain fatty acids (10.8 +/- 0.7), and energy (78.3 +/- 2.0 kcal/dl) than either or both those from 32 to 36 wk (PT) and term (T) gestations. PT collections did not differ from T milk with regard to nitrogen (250 +/- 13 versus 259 +/- 13), total fatty acids (3.94 +/- 0.20 versus 3.20 +/- 0.30), percentage medium chain fatty acids (9.1 +/- 0.5 versus 8.1 +/- 0.7) and energy (69.0 +/- 2.7 versus 66.6 +/- 2.4). Although postpartum age (5 to 10 versus 11 to 30 days) did not change the nutrient and energy content of VPT, PT, and T collections, it is only in 11 to 30 day VPT milk that nitrogen and energy content became higher (p less than 0.05) than either or both PT and T milk. We conclude that the differences in macronutrient composition of PT milk are limited to VPT milk and the data from repeated milk collections in the same mother (28 wk) suggest that there is considerable variability in its composition.

Beneficial effects of fish-oil supplements on lipids, lipoproteins, and lipoprotein lipase in patients with glycogen storage disease type I.

Glycogen storage disease type I (GSD-I) is frequently complicated by severe hyperlipoproteinemia and the increased potential risk of premature atherosclerosis. The effects of fish-oil supplementation [MaxEPA, 10 g.(1.73 m2)-1 for 3 mo] were investigated prospectively in seven hyperlipoproteinemic patients with GSD-I. Hypertriglyceridemia and hypercholesterolemia improved after 3 mo of fish-oil treatment, decreasing 49% (P < 0.005) and 23%, respectively. This was accompanied by a reduction in both low-density-lipoprotein (LDL) cholesterol (25%, P < 0.03) and apolipoprotein B (40%) and by increased high-density-lipoprotein increased (HDL) cholesterol (30%, P < 0.002) and apolipoprotein A-I (31%, P < 0.05). Low pretreatment ratios of HDL to total cholesterol and HDL to LDL, indicators of elevated atherosclerosis risk, increased significantly (P < 0.05). Plasma lipoprotein profile as well as lipoprotein composition [triglyceride (TG) enrichment and cholesteryl depletion] improved. Reduced TG concentrations were due to enhanced fat catabolism, as evidenced by the significantly increased hepatic and extrahepatic lipoprotein lipase activity (P < 0.05). Withdrawal of fish oil for 3 mo was associated with a return to pretreatment abnormalities in plasma lipids and lipoproteins. Fish-oil supplementation thus improves the hyperlipoproteinemia in GSD-I and may significantly reduce the risk of premature atherosclerotic cardiovascular disease.

High incidence of upper gastrointestinal tract involvement in children with Crohn disease.

This retrospective study of Crohn disease in 230 children and adolescents with a mean age of 12.5 years at the time of diagnosis and an average follow-up of 6.6 years showed that 30% had lesions of the esophagus, stomach, and duodenum. Three patients had Crohn disease isolated to the upper gastrointestinal tract. The 169 patients with both small and large bowel disease were at greater risk (33%, P less than .05) of having upper gastrointestinal lesions than the 37 with isolated small bowel disease and the 21 with disease limited to the colon and/or rectum. An aggregate of symptoms and signs more likely present in those with upper gastrointestinal involvement included: dysphagia, pain when eating, nausea and/or vomiting, and aphthous lesions of the mouth. Furthermore, weight loss was more severe and hypoalbuminemia more frequent. Because upper gastrointestinal series x-ray studies failed to detect upper gastrointestinal lesions in 13 patients of 69 of those with upper gastrointestinal disease, endoscopy should be considered in all children and adolescents in whom a diagnosis of Crohn disease is entertained. Endoscopy and biopsy of the upper gastrointestinal tract should be done in any patient with symptoms suggestive of proximal involvement. Finally, in view of the fact that endoscopy established the diagnosis of Crohn disease in five patients previously thought to have chronic ulcerative colitis, the procedure should routinely be performed in all patients with chronic ulcerative colitis or indeterminate colitis before surgery is performed.

Taurine improves the absorption of a fat meal in patients with cystic fibrosis.

The effect of taurine supplementation on the absorption of a fat meal was evaluated in patients with cystic fibrosis. In a cross-over design study, five patients with cystic fibrosis (12.1 +/- 2.6 years of age) and three control subjects received either placebo or taurine (30 mg/kg/d) for two 1-week periods, a month apart, followed by a fat meal test. Blood samples were drawn 0, 1, 2, 3, 5, 8 hours after the meal. Four patients with cystic fibrosis and severe steatorrhea despite appropriate enzyme therapy showed a significant (P less than .05) improvement in the absorption of triglycerides, total fatty acids, and linoleic acid while receiving taurine supplements. Three control subjects and one child with cystic fibrosis and mild steatorrhea receiving enzyme therapy did not experience such an effect. The difference in triglyceride absorption, when calculated as the area under the curve, receiving and not receiving taurine was significantly (P less than .05) correlated with the degree of steatorrhea. Furthermore, in contrast to control subjects, the fatty acid composition of chylomicrons in these four study patients showed important discrepancies with that of the fat meal and was corrected, in part, by taurine supplementation. These results suggest that taurine supplementation could be a useful adjunct in the management of patients with cystic fibrosis with ongoing fat malabsorption and essential fatty acid deficiency.

Reye's syndrome: relapses and neurological sequelae.

Twenty-two children aged 2 months to 11 years were seen at our institution from January 1970 to March 1975 with clinical, laboratory, and/or histological features consistent with the diagnosis of Reye's syndrome. There were three pairs of siblings. Severity of the illness ranged from relatively benign to rapidly fatal forms. Five received live attenuated vaccines within the three weeks prior to admission. Four relapsed 1 to 21 months after the initial episode, and in one there were multiple recurrences. Six developed major neurological sequelae. All patients graded levels IV and V by EEGs on admission subsequently died in contrast to none from grades 1 and 2. Peritoneal dialysis was carried out in the more severely affected patients. The procedure did not influence final outcome as predicted by the first EEG and is thought to be of limited value.

Primary sclerosing cholangitis in children: study of five cases and review of the literature.

Primary sclerosing cholangitis in five children is described and 78 cases in the pediatric age group are reviewed. In 24% of the cases, primary sclerosing cholangitis is not associated with an underlying disease and may appear to be prolonged cholestasis of infancy. When an associated condition is present, chronic inflammatory bowel disease, in particular ulcerative colitis, is most common (47%). Histiocytosis X and a variety of immune disorders account for 15% and 10% of cases, respectively. Primary sclerosing cholangitis should be considered in the differential diagnosis of chronic liver disease in the pediatric age group, even in young infants. Results of this survey demonstrate that neither clinical features nor liver function tests are reliable diagnostic predictors, that histologic changes are often nonspecific, and that cholangiography is essential to establish the correct diagnosis.

Effect of taurine on total parenteral nutrition-associated cholestasis.

A decrease in the formation/secretion of bile has been well documented in animals on total parenteral nutrition (TPN). Either an excess or an imbalance of amino acids (AA) has been most often implicated. In view of recent work showing that taurine promotes bile flow, bile acid secretion, and protects against hepatotoxic bile acids, the effect of adding taurine (15 mg/dL) to an AA solution was examined in guinea pigs on TPN for 3 days. The TPN-taurine group had a larger bile flow than the group without taurine and had bile acid secretory rates (BASR) similar to those of controls who were on saline by central catheter and had free access to food. Bile composition showed an increase in the secondary bile acid, 7-ketolithocholate and a concomitant decrease in chenodeoxycholate (CDC) in both experimental groups. Taurine led to a reversal of the usual predominance of glycine over taurine conjugated bile acids as well as to increases in HCO3 in cholesterol secretion. In response to a challenge with a large load of CDC, the TPN-taurine animals increased their BASR beyond those observed in the two other groups. These observations suggest that the addition of taurine to TPN solutions could play a role in the prevention of altered biliary function associated with AA solutions.

Continuous elemental enteral alimentation in the treatment of children and adolescents with Crohn's disease.

Ten pediatric patients, aged 8.5-19 years, with active symptomatic Crohn's disease, received a three-week period of continuous elemental enteral alimentation with no other form of treatment. All patients in this study were selected according to the following criteria, which were applied consecutively: (1) newly diagnosed patients with no previous treatment for Crohn's disease, (2) disease activity index over 200, and (3) no complication requiring surgery. All patients experienced a clinical remission and improved their immunologic and nutritional status during the elemental enteral alimentation. The mean disease activity index for the whole group was 307.0 +/- 23.6 (range: 203 to 413) before and 69.2 +/- 11.4 (range: 15 to 114) after the feeding period. Significant increases in body weight, triceps skinfold, mid-arm circumference, serum transferrin and mean percentage of T lymphocytes were also observed. Following cessation of enteral alimentation, a small declining dose of prednisone was used during a one-year follow-up period. Eight of the ten patients were still in clinical remission three months after the feeding period and their nutritional status had continued to improve during that period of time.

Total parenteral nutrition-associated cholestasis in rats: comparison of different amino acid mixtures.

It has been suggested that the quantity of amino acids perfused is a pathogenetic factor in total parenteral nutrition (TPN)-associated hepatotoxicity. However, the effect of the qualitative pattern of amino acid solutions has not been studied. Rats on parenteral nutrition for 5 days received 10.2 g of dextrose and 3.4 g of amino acids daily. Bile flow (microliter/min/g liver protein) after administration of Vamin was 16.2 +/- 0.8, which was similar to that in controls given chow and dextrose iv, but it was significantly higher (p less than 0.001) than those on Travasol (12.3 +/- 0.8). The decrease in bile flow was not related to the large concentrations of alanine and glycine present in Travasol. However, the addition to Travasol of serine present only in Vamin increased bile flow significantly. Bile acid secretion rate, biliary lipid constituents, calcium, sodium, and glucose showed little change. In contrast, alpha-amino nitrogen was increased (p less than 0.05) in Vamin-perfused animals. Steatosis was noted in only a few animals in the Travasol group, and was not associated with an increase in the triglycerides content of the liver. Glycogen and protein content of the livers did not differ. The data show that the composition of amino acid solutions may be a determinant of TPN-induced cholestasis and suggest that the presence of methyl donor amino acids may have a protective effect.

Childhood antecedents of adult degenerative disease.

The pathogenetic links between diet and diseases such as hypertension and atherosclerosis remain the subject of much controversy. This article reviews the evidence about the relationship between diet and these two widespread adult conditions, proposes an approach for their early recognition, examines the rationale and safety of dietary changes, and formulates specific recommendations.

Steatorrhea and disorders of chylomicron synthesis and secretion.

Knowledge concerning the absorptive phase of fat remains relatively scanty as compared to the wealth of information available on the digestive phase. However, the past years have seen important developments in our understanding of chylomicron formation and secretion. This has come about thanks to clinical studies of rare congenital disorders of chylomicron synthesis and exocytosis and to the creation of experimental models.

Bile formation and hepatic plasma membrane composition in guinea-pigs and rats.

We compared bile formation, and biliary and liver plasma membrane composition in guinea-pigs and rats in an attempt to explain the observation that the bile flow rate and the bile acid independent fraction of bile flow (BAIF) in guinea-pigs is about five to seven times higher than in rats. Analysis of electrolytes in bile showed that bicarbonate was significantly [acid] higher in guinea-pigs while Cl-, phosphate and Ca2+ were markedly lower than in rats. High bile independent secretion in guinea-pigs was associated with a significantly lower concentration of total bile acid, phospholipid and cholesterol than in rats. Bile acid distribution studies showed that glycine conjugated chenodeoxycholate and ketolithocholate were the main bile acids in guinea-pigs, while taurine conjugated cholate and muricholate were the predominant bile acids in rats. Total fatty acid analysis of bile indicated that in rats the major fatty acids were palmitic acid (C16:0) and linoleic acid (C18:2, n-6). In guinea-pigs, the contribution of these fatty acids was lower than in rats and compensated with a significantly higher percentage of oleic acid (C18:1, n-9). Concentrations of anionic polypeptide fraction (APF), an acidic calcium binding apoprotein closely associated with biliary phospholipid and cholesterol secretion was also significantly lower in guinea-pigs. Canalicular plasma membrane analysis showed that as compared with rats, specific activities of Na+,K+ ATPase, and cholesterol and phospholipid content were markedly lower in guinea-pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid abnormalities in pancreatic tissue of streptozotocin-induced diabetic rats.

Pancreatic lipid and fatty acid composition was determined in streptozotocin-induced diabetic rats and compared to control and insulin-treated diabetic rats. A pronounced decrease of total fatty acids was recorded and mainly accounted for by a drop of fatty acids in glycerides. Cholesterol, on the other hand, was significantly increased two- to three-fold, leading to an elevated cholesterol/phospholipid ratio. Morpho-cytochemical studies confirmed these findings because the multiple lipid droplets present in acinar cells of diabetic animals were found to be of cholesterol nature. The major alterations in phospholipid-fatty acid composition were characterized by an increase of linoleate coupled to a decrease of monounsaturates and arachidonate, suggesting defective metabolism of saturates and of linoleate. This was further supported by fatty acid ratios that suggested low delta 5 and delta 9 desaturation. Daily administration of insulin for 10 days restored and overcorrected the various lipid alterations. This study suggests that there are alterations in lipid composition and metabolism in the exocrine pancreas of chronic streptozotocin-induced diabetic rats. Their possible role in the mechanism regulating pancreatic function and secretion remains to be elucidated.

Plasma and lipoprotein fatty acid composition in glycogen storage disease type I.

Nocturnal intragastric feeding has been shown to be an effective means to improve clinical and biochemical features in glycogen storage disease type I (GSD-I). In this study, we investigated the fatty acid patterns in a whole plasma and in circulating lipoproteins in patients on this therapy. The results demonstrated massive concentration of total fatty acids coupled with higher levels of triglycerides, free cholesterol, cholesterol ester and phospholipids. This hyperlipidemia involved all fatty acids without distinction of carbon or bond numbers. However, the increase was more pronounced for saturated than polyunsaturated fatty acids, as was demonstrated by the ratios of both oleic acid to linoleic acid (1.91 +/- 0.40 vs 0.80 +/- 0.09 in controls) and of omega 3 + omega 6 to omega 9 fatty acid families (0.92 +/- 0.11 vs 1.66 +/- 0.08 in controls). The fatty acid patterns in very low (VLDL), low (LDL) and high (HDL) density lipoprotein showed substantial differences in composition, reflecting an association between an abnormal lipoprotein pattern and essential fatty acid deficiency. Furthermore, GSD-I patients exhibited a significant increase in VLDL (17 +/- 2 vs 47 +/- 7 mg/dl) and LDL cholesterol (124 +/- 7 vs 206 +/- 24 mg/dl), coupled with a decrease in HDL cholesterol (49 +/- 4 vs 28 +/- 3 mg/dl). These data documenting high LDL cholesterol and low HDL cholesterol associated with an increased concentration and proportion of saturated fatty acids suggest that GSD-I patients on nocturnal intragastric feeding are at high risk for atherosclerosis and its complications.

The role of gastric lipolysis on fat absorption and bile acid metabolism in the rat.

In vivo studies were carried out in young Sprague-Dawley rats to examine the role of gastric lipolysis on fat absorption and bile acid metabolism. When fed by gastric perfusion 5 times (corn oil, 4 g/day) their usual dietary intake of fat, rats deprived of lingual lipase by the creation of an esophageal fistula had a significant degree of fat and bile acid malabsorption as well as a shortened bile acid half-life when compared to animals with a gastrostomy. The % fat absorption, bile acid loss and bile acid pool were normal in 2 groups of esophageal fistula rats fed the same quantity of corn oil or twice (8 g/day) that amount as a fine emulsion. In view of a negligible gastric lipase activity in animals with an esophageal fistula and of decreased hydrolysis of a triglyceride test meal, these data suggest that gastric lipolysis is of physiological importance in situations where lipolytic mechanisms are stressed by a large fat intkae. Its principal role is to potentiate intestinal lipolysis by facilitating the emulsification of dietary lipids through its formed products and, therefore, the contact of pancreatic lipase with its substrates.