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PubMed1991

Lipid metabolism in the obese Zucker rat. Disposal of an oral [14C]triolein load and lipoprotein lipase activity.

Oxidation in vivo of [14C]triolein to 14CO2 was significantly lower in obese (fa/fa) Zucker rats as compared with their lean (+/?) controls. In response to a 24 h starvation period, both lean and obese rats showed an enhanced rate of [14C]triolein oxidation. There were, however, no changes in the rate of intestinal absorption of [14C]triolein between the lean and obese animals. Conversely, the total tissular [14C]lipid accumulation was significantly higher in white adipose tissue, carcass and plasma in the obese animals, whereas that of brown adipose tissue was lower. This was associated with a marked hyperinsulinaemia and hypertriglyceridaemia in the fa/fa animals. Starvation dramatically decreased [14C]lipid accumulation in white adipose tissue of the lean Zucker rats, but had no effect in the obese rats. The lipogenic rate of the obese rats was significantly higher than that of lean rats in liver, white adipose tissue, skeletal muscle and carcass. Lipoprotein lipase activity (per g of tissue) was significantly lower in both white and brown adipose tissue of obese versus lean rats; however, total activity was higher in both tissues. Starvation significantly lowered perigenital-adipose-tissue lipoprotein lipase activity in the lean groups, and had no effect in the obese ones. These results demonstrate that the tissue capacity of exogenous lipid uptake is involved, but cannot be the only factor influencing the maintenance of obesity in these animals. Thus, in the adult fa/fa rat, the large increase in obesity is not solely dependent on a deviation of energy-producing substrate metabolism towards the storage of lipids in white fat. Other factors, such as a low rate of oxidation, a high lipogenic rate and decreased brown-adipose-tissue activity are involved in the perseverance of the obesity syndrome.

Animals↗
PubMed1998

Metabolism of parenterally administered fat emulsions in the rat: studies of fatty acid oxidation with 1-13C- and 8-13C-labelled triolein.

To reassess the hypothesis that fatty acid catabolism occurs to completion via beta-oxidation, male Sprague-Dawley rats receiving continuous total parenteral nutrition (TPN) including 43% energy as fat were infused with [1-(13)C]- or [8-(13)C]triolein. Expired CO2 was collected continuously for 4 h and its 13C:12C ratio determined by isotope-ratio mass spectrometry. Bicarbonate retention was also assessed over 4 h by infusion of NaH14CO3 and measurement of the expired 14CO2. A possible loss of label from [8-(13)C]oleic acid from the citric acid cycle via labelled acetyl-CoA without oxidation to CO2 was assessed by infusing further animals with acetate labelled with 14C either at C atoms 1 or 2 and determination of its conversion to expired 14CO2. At isotopic steady state, 63.2 (SE 1.6)% (n 8) of the infused [1-(14)C]acetate and 46.0 (SE 1.2)% (n 8) of [2-(14)C]acetate was recovered as expired 14CO2. After correction for bicarbonate retention and non-oxidative isotope loss, 37.3 (SE 1.2)% (n 20) of the [1-(13)C]triolein was found to have been oxidized, whereas 32.6 (SE 1.0)% (n 20) of the [8-(13)C]triolein was oxidized (P < or = 0.01). The lower oxidation of the C atom at position 8 of oleic acid than that at position 1 indicates incomplete oxidative breakdown of the fatty acid after entering beta-oxidation.

Acetates↗
PubMed2007

Selective removal of organochlorine pesticides (OCPs) from aqueous solution by triolein-embedded composite adsorbent.

A novel composite adsorbent (CA-T) was used for the selective removal of organochlorine pesticides (OCPs) from aqueous solution. The adsorbent was composed of the supporting activated carbon and the surrounding triolein-embedded cellulose acetate membrane. Scanning electron microscopy (SEM), N2 adsorption isotherms and fluorescence methods were used to characterize the physicochemical properties of CA-T. Triolein was perfectly embedded in the cellulose acetate membrane and deposited on the surface of activated carbon. The adsorbent was stable in water and no triolein leakage was detected during the test periods. Some organochlorine pesticides (OCPs), such as dieldrin, endrin, aldrin, and heptachlor epoxide, were used as model contaminants and removed by CA-T in laboratory batch experiments. The adsorption isotherm followed the Freundlich equation and the kinetic data fitted well to the pseudo-second-order reaction model. Results also indicated that CA-T appeared to be a promising adsorbent with good selectivity and satisfactory removal rate for lipophilic OCPs from aqueous solutions when present in trace amounts. The adsorption rate and removal efficiency for lipophilic OCPs were positively related to their octanol-water partition coefficients (log K(ow)). Lower residual concentrations of OCPs were achieved when compared to granular activated carbon (GAC).

Adsorption↗
PubMed1987

Rapid induction of essential fatty acid deficiency by intragastric infusion of triolein-supplemented total parenteral nutrition solutions: evidence of increased hepatic cholesterol esterification in the rat.

Rats were fed linoleic acid from a safflower oil emulsion or triolein-supplemented total parenteral nutrition solutions by continuous intragastric infusion for 7 and 14 d. Biochemical signs of essential fatty acid deficiency (EFAD) developed in rats supplemented with triolein compared with those receiving linoleic acid, and the relationship between hepatic cholesterol esterification and the distribution of free cholesterol in plasma lipoproteins was investigated in the EFAD and control animals. Results indicate that hepatic triglyceride (TG) and cholesterol ester content are greater and plasma levels of TG and cholesterol are lower in triolein-supplemented groups. Hepatic accumulation of cholesterol esters is associated with an increase in hepatic acyl-CoA:cholesterol acyltransferase activity and also with plasma very low density lipoprotein (VLDL) and high-density lipoprotein (HDL), which contain a greater proportion of cholesterol esters. These data suggest that EFAD can be rapidly induced with continuous intragastric feeding and that hepatic accumulation of cholesterol esters and enrichment of VLDL and HDL with cholesterol esters are early indicators of EFAD in the rat.

Acyl Coenzyme A↗
PubMed2000

Fat malabsorption assessed by 14C-triolein breath test in HIV-positive patients in different stages of infection: is it an early event?

The aim of this study was to evaluate fat absorption in HIV-positive (HIV+) patients in different phases of HIV infection using a 14C-triolein breath test. We distributed 47 HIV+ patients according to the 1993 Centers for Disease Control Revised Classification: 20 in Group 2 (A1 or A2) and 27 in Group 3 (B1, B2, A3, B3, or C). Ten HIV-negative healthy subjects comprised the control group (Group 1). All individuals underwent a 14C-triolein breath test. Parasitic infection was evaluated through three stool exams, including Cryptosporidium and Isospora investigation. The median value of cumulative 6 hours' 14C excretion expressed as percentage of the 14C given as triolein was significantly higher in Group 1 (8.4%) than Group 2 (5.5%) or Group 3 (3.4%), p = 0.04 and p << 0.01, respectively. Fat malabsorption was found in 25% of Group 2 individuals, 52.6% of those without diarrhea in Group 3, and was correlated with CD4+ lymphocyte counts (p << 0.01). Fat malabsorption is a common feature in advanced stages of HIV infection, even in the absence of diarrhea and is also present in asymptomatic HIV+ patients. These findings suggest that malabsorption is an early event in HIV-infected individuals and is correlated with the degree of immunosuppression.

Adult↗
PubMed2004

Effect of triolein emulsion on the blood-testis barrier in cats.

PURPOSE: Although the blood-testis barrier (BTB) is beneficial physiologically, it acts as an obstacle to chemotherapy. We wished to determine whether a triolein emulsion could alter the permeability of the BTB in cats. MATERIALS AND METHODS: An emulsion of 0.05-mL triolein in 20 mL of saline was infused into the abdominal aorta just proximal to the branching of the renal arteries of each of 15 cats (embolic group). As controls, 12 cats were each similarly infused with 20 mL of normal saline (control group). Pre and postcontrast MR images were obtained 30 minutes and 2 hours after embolization. The images were analyzed for the presence and degree of contrast enhancement (qualitative analysis), and the contrast enhancement ratios (CER) derived from one testis of each animal were compared and statistically analyzed by the mixed linear model (quantitative analysis). RESULTS: Contrast enhancement of the testis was observed in both groups at both time points, but it was more prominent in the embolic group. The CERs in the embolic group (0.63 at 30 minutes, 0.42 at 2 hours) were significantly higher than in the control group (0.36 at 30 minutes, 0.28 at 2 hours; P = 0.0001). In each group, the CERs at 2 hours were significantly lower than those at 30 minutes (P = 0.006). CONCLUSION: Intra-arterial infusion of triolein emulsion increased the permeability of the BTB. This result may be useful in future studies of BTB disruptions caused by fat emulsions.

Animals↗
PubMed2004

Evaluation of the 13C-triolein breath test for fat malabsorption in adult patients with cystic fibrosis.

BACKGROUND AND AIMS: A simple non-invasive test not requiring the use of radioactive isotopes is required to assess fat malabsorption in adult cystic fibrosis (CF) patients. Breath tests using substrates labeled with 13C meet these conditions. The 14C-triolein breath test is sensitive and specific for measuring fat malabsorption, but involves radiation exposure. The aim of this study was to examine the utility of a test using a 13C label and to determine whether pancreatic replacement therapy would return the test to the values of a normal control group. METHODS: 13CO2 recovery was assessed after an overnight fast in six adult patients with CF, both with and without pancreatic enzyme replacement therapy (PERT) in the usual dose for a light snack, in a randomized order, on different days. Studies were also performed in eight healthy volunteers after oral ingestion. Subjects drank 50 mL of a liquid meal mixed with 200 microL 13C-triolein and breath samples were collected by blowing through a straw into collection tubes every 30 min for 6 h. The effect of gastric emptying was assessed by comparison of oral ingestion with intraduodenal infusion. Intra-individual variability was assessed in nine volunteers by repeating the breath test after drinking the test meal on a separate day. RESULTS: Compared with healthy subjects there was virtually no recovery of 13CO2 in CF patients without PERT. The median (interquartile range) cumulative percentage dose recovery (cPDR) at 6 h was 3% (0-8) in CF patients compared with 28% (22-41) in healthy controls (P < 0.01). Fat absorption was normalized (37%) (36-43) after ingestion of PERT. Gastric emptying delayed the peak in 13CO2 recovery, but there was no difference in the cPDR at 6 h. There was no difference in recovery between days 1 and 2. CONCLUSIONS: The 13C-triolein breath test is a simple and reproducible method to measure fat malabsorption. The test provides a screening technique for fat malabsorption in adult CF patients and may be useful for monitoring the lowest effective dose of PERT.

Administration, Oral↗
PubMed1983

The effect of duodenal administration of fatty acids, triolein, liquid paraffin and lecithin on plasma neurotensin-like immunoreactivity (p-NTLI) in the rat.

The effect of intraduodenal administration of various types of lipids on the concentration of p-NTLI has been studied on anesthetized rats. Oleic acid, sodium oleate, triolein, linoleic acid, linolenic acid, arachidonic acid, butyric acid, liquid paraffin, phosphatidyl choline (lecithin) and saline were administered. Oleic acid, triolein, linoleic acid and linolenic acid significantly increased the integrated response of p-NTLI. The maximal concentration of p-NTLI was reached 40 min after administration of oleic acid. However after instillation of triolein, the maximal concentration was reached at 100 min which was significantly later. The results indicate that the response of p-NTLI following administration of fat into the duodenum of rats is a specific event caused by fatty acids rather than by lipophilic substances in general. Of the substances tested 18-carbon fatty acids were the most effective in increasing the concentration of p-NTLI. Shorter- or longer-chain fatty acids were less effective. The degree of unsaturation, i.e. the presence of one or more double bounds is also of importance. Triglycerides seem to be hydrolysed to fatty acids before they may bring about an increase in the concentration of p-NTLI. The charge of lipids seems to be critical since the sodium salt of oleic acid had limited effects. Arachidonic acid did not change the integrated response of p-NTLI indicating that products of cyclooxygenase and lipoxygenase pathways are not involved in the fatty acid induced release of NTLI.

Animals↗
PubMed1991

Plasma clearance of emulsified triolein in conscious rats: effects of phosphatidylcholine species, cholesterol content and emulsion surface physical state.

In vivo clearance of an emulsified triglyceride from rat plasma is strongly influenced by the phosphatidylcholine molecular species and the cholesterol content of the emulsion. Chylomicron-sized, glycerol-tri[9,10-3H]oleate (triolein)-sonicated emulsions containing 2-3 or 9-14 mol% unesterified cholesterol and specific phosphatidylcholines (egg, dimyristoyl, dipalmitoyl, distearoyl) were prepared above the phospholipid gel----liquid crystalline transition temperatures and injected intravenously into awake, non-fasting rats in bolus doses of 1-3 mg lipid. The emulsified triolein was cleared from plasma both by lipolysis during circulation and by uptake of emulsion particles or their remnants into tissues. Increasing the cholesterol content greatly accelerated particle clearance from plasma when emulsions were made with mixed-chain (egg) phosphatidylcholine, but prolonged their circulation time when the emulsions contained saturated phosphatidylcholines. The relative amounts cleared by reticuloendothelial versus liver parenchymal cells were influenced both by the cholesterol content and the phosphatidylcholine species of the emulsions. Significant triolein lipolysis in plasma occurred only with egg or dimyristoyl phosphatidylcholine emulsions containing 2-3% cholesterol and this lipolysis was blocked by increasing the cholesterol content. No lipolysis occurred when emulsions contained dipalmitoyl or distearoyl phosphatidylcholine, irrespective of cholesterol content.

Animals↗
PubMed1990

Effect of diet on triolein absorption in weanling rats.

To determine the effect of altered dietary fat intake on the rate of fat absorption in the intact animal, we fed male weanling rats either a high fat-low carbohydrate (HF-LC) (calories: 67% fat, 10% carbohydrate, 20% protein) or low fat-high carbohydrate (LF-HC) (calories: 10% fat, 67% carbohydrate, 20% protein) diet for 8 days. Absorption of [14C]triolein was estimated by determining 1) 14CO2 expiration in breath, 2) intestinal triglyceride output using Triton WR-1339, an inhibitor of lipoprotein lipase, and 3) quantitating the disappearance of labeled triolein from the gastrointestinal tract. Changes in the activity of pancreatic lipase and amylase confirmed the adaptation to altered fat and carbohydrate intake. Animals fed the HF-LC diet exhibited approximately twofold greater triolein disappearance, oxidation, and intestinal triglyceride output compared with animals fed LF-HC. There was also a highly significant linear relationship between 14CO2 excretion and intestinal triglyceride output in both diet groups. These data show that high dietary fat content markedly enhances in vivo fat absorption in the weanling rat.

Animals↗
PubMed1983

Sequential hydrolysis of three acyl ester bonds in triolein molecule by human gastric juice lipase.

Specificity of gastric juice lipase concerning the sequential hydrolysis of three acyl ester bonds of triolein molecule has been compared with that of pancreatic lipase. The rates of the individual hydrolytic steps were calculated by applying the method based on the amounts of chromatographically separated hydrolysis products present upon the incubation of tritium-labelled triolein with a lipolytic enzyme. It was found that in the case of gastric lipase the rates of all three steps of triolein hydrolysis are similar, whereas in the case of pancreatic lipase the last step proceeds at a much slower rate than the preceding ones.

Gastric Juice↗
PubMed1978

Intestinal lymph chylomicron cholesteryl ester during duodenal triolein infusion at increasing rate.

Chylomicron lipid composition in mesenteric lymph fistula rats was followed during duodenal triolein infusion at three rates. Esterified cholesterol decreased progressively in all groups as triglyceride transport continued, and the rate of decrease was reciprocally related to the triolein infusion rate. Suppression of cholesterol ester synthesis may spare unesterified cholesterol for chylomicron membrane formation. Ratios of triglyceride to phospholipid and to unesterified cholesterol increased with the duration of triglyceride secretion, while the chylomicron surface lipid composition remained constant over time. The rate of increase in the core:surface lipid ratios was the same irrespective of the triolein transport rate.

Animals↗
PubMed1982

Effect of dietary fat and cholesterol on uptake of oleic acid and triolein by everted sacs of bovine small intestine.

The influence of dietary fats on in vitro lipid absorption by bovine intestine was studied in 14 calves. Holstein bull calves were fed for 16 wk five liquid diets containing skim milk plus either 3.5% milk fat, 3.5% tallow, 3.5% tallow and .2% cholesterol, 7.0% tallow, or 7.0% tallow and .2% cholesterol. Uptake of oleic acid or triolein by everted jejunal or ileal sacs was measured after incubation for 30 min at 37 degrees C in pH 7.4 micellar solutions containing tritium-labeled oleic acid or tritium-labeled triolein. Lipids were extracted from homogenates of sacs and separated into lipid classes by thin layer chromatography. Equal amounts of oleic acid were taken up by jejunal or ileal sacs. Triolein uptake was less than oleic acid uptake, but uptakes by jejunal or ileal sacs did not differ. Oleic acid incorporation into triglyceride was three to four times greater in intestinal sacs from milk fat-fed calves than in sacs from calves fed either 3.5 or 7% tallow. Oleic acid incorporation in intestinal sacs from calves fed cholesterol as well as tallow was equal to that in milk fat-fed calves. Intestinal uptake and metabolism of oleic acid proceeded faster when calves were fed milk fat than when fed tallow. The lower intestinal incorporation with tallow increased if cholesterol was fed, suggesting that cholesterol either stimulated absorption or increased esterification.

Animals↗
PubMed1975

Effect of partial constriction of the superior mesenteric artery upon absorption of d-xylose, labeled triolein and labeled albumin.

Intestinal adsorption of triolein, Risa and d-xylose was determined before and after reduction of blood flow in the superior mesenteric artery. Absorption of d-xylose did not change, but absorption of triolein and Risa appeared to be slightly improved after arterial constriction, even if the artery was completely thrombosed. Enhancement in absorption of Risa and triolein was probably the result of extensive collateral formation around the constricted superior mesenteric artery.

Animals↗
PubMed1975

Effects and distribution of acute fat embolism in spontaneously breathing dogs using radioactive carbon triolein.

The acute effects of a triolein infusion in dogs were secondary to the mechanical effects of this neutral fat which was distributed in the pulmonary and systemic vascular tree of all organs without inflammatory change. Hypoxia developed immediately and became progressively worse as the infusion was continued. Pulmonary hypertension developed during the fat infusion without pneumonia, congestive heart failure or pulmonary edema. There was a slow leak of 14C triolein into the systemic circulation rather than a rapid shower, and this radioactive fat was recirculated between the pulmonary and systemic vasculature. Seventy-six per cent of the 14C triolein was retained in the lungs. Terminally, the dogs had a respiratory arrest without cardiac decompensation, cardiac arrest or pulmonary edema; cerebral fat embolism in addition to severe hypoxia appears to be the cause.

Acute Disease↗
PubMed1983

Estimation of lipid assimilation from faecal samples using 14C-triolein as tracer and 51CrCl3 as non-absorbable marker.

14C-triolein was investigated as tracer of dietary lipids from faecal measurements in 48 consecutive gastrointestinal patients. Simultaneously, 51CrCl3 was investigated as non-absorbable marker. Faecal 51Cr was measured in a whole-body scintillation counter and faecal 14C by means of a combustion technique. This technique permitted accurate measurement of faecal 51Cr and faecal 14C in each stool collected over a 6-day period. The investigation showed that the transit time of 51Cr was slightly shorter than the transit time of 14C-triolein in patients with high faecal excretion of 14C. Nevertheless, total faecal 14C, estimated from the ratio between 14C and 51Cr in two stools, correlated very closely with measured, cumulative faecal 14C (r = 0.99, P less than 0.001). 51CrCl3 was therefore considered useful as a non-absorbable marker. The 14C-labelling of triolein was stable during gastrointestinal transit. Qualitatively, estimated faecal 14C agreed with faecal fat diagnosing steatorrhoea in 97% (95% confidence limits 90-100%) of the patients with quantitative faecal collections. Quantitatively, a significant correlation with faecal fat was found (r = 0.82, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Rat liver retinyl palmitate hydrolase activity. Relationship to cholesteryl oleate and triolein hydrolase activities.

Studies were conducted to explore relationships in rat liver between retinyl palmitate hydrolase activity and the hydrolytic activities against cholesteryl oleate and triolein. Previous studies have shown positive correlations between these three lipid ester hydrolase activities. In order to extend this work, the hydrolase activities were further purified and characterized. The activities against cholesteryl oleate and triolein resembled retinyl palmitate hydrolase activity in showing great variability from rat to rat as assayed in vitro. The relative levels of the three activities were highly correlated with each other over a 50-fold range of activity in a series of 66 liver homogenates. Partial purification (approx. 200-fold) in the absence of detergents was achieved by sequential chromatography of an acetone powder extract of liver on columns of phenyl-Sepharose, DEAE-Sepharose and heparin-Sepharose. The three hydrolase activities copurified during each of these chromatographic steps. The properties of the three copurifying activities were similar with regard to stimulation of activity by trihydroxy bile salts, pH optimum (near 8.0), and observance of Michaelis-Menten-type saturation kinetics. The three activities were different in their sensitivity towards the serine esterase inhibitors diisopropylfluorophosphate and phenylmethanesulfonyl fluoride, and in their solubility properties in 10 mM sodium acetate, pH 5.0. Thus, triolein hydrolase activity was much less sensitive than the other two activities to the two inhibitors. In addition, the activity against cholesteryl oleate could be separated from the other two activities by extraction of an acetone powder with acetate buffer, pH 5.0. These results indicate that the three lipid hydrolase activities are due to at least three different catalytically active centers, and at least two distinct and separable enzymes. It is likely that three separate but similar enzymes, that appear to be coordinately regulated, are involved.

Animals↗
PubMed1984

Measurement of fatty acid oxidation in premature newborn infants with the 13C-triolein breath test.

The 13C-triolein breath test is a method giving evidence of extent and rate of fatty acid oxidation in newborn infants on parenteral nutrition. The test has the special advantage of being non-invasive. Triolein labeled with the stable carbon isotope 13C and emulsified in soybean-oil is used as a tracer. 10 mg of 13C triolein per kg body weight are administered intravenously. The 13CO2 resulting from the fatty acid oxidation is analysed in expired breath by ratio-mass-spectrometry. The calculated 13C elimination is representative of the rate of fatty acid oxidation during the examination period. First studies on 15 premature infants have shown that an average of 27.0 +/- 1.8% of the dose administered is oxidized within 4 h. The present results suggest that the oxidation rate may be related to the maturity of the prematurely born infants.

Journal Article↗