Plasma Triglyceride Fatty Acid Research Articles

Fenofibrate ameliorates insulin resistance in lipoprotein lipase heterozygous knockout mice and its possible mechanisms

Objective To investigate the effect of fenofibrate on glucolipid metabolism and insulin sensitivity in lipoprotein lipase heterozygous knockout(LPL+ /-)mice, and to explore its mechanism. Methods LPL+ /- mice and wild type(WT)C57 mice were selected and divided into 3 groups(n=6 each group): LPL+ /-(FB)group, LPL+ /-(W)group, and WT group. Mice in LPL+ /-(FB)group were gavaged with fenofibrate(50 mg·kg-1·d-1)for 8 weeks. Mice in LPL+ /-(W)and WT groups were orally fed with the same volume water as that in LPL+ /-(FB)group for 8 weeks. Body weight was observed. Plasma triglyceride(TG)and free fatty acid(FFA)were measured. Intraperitoneal glucose tolerance test in 3 groups of mice were performed. The glucose area under the curve(AUCG)and homeostasis model assessment for insulin resistance index(HOMA-IR)were calculated. Insulin-stimulated Ser473 Akt phosphorylation in liver and skeletal muscle was measured by Western blot. Reactive oxygen species(ROS)levels in liver and skeletal muscle were determined by dihydroethidium staining method and superoxide dismutase(SOD)and catalase(CAT)mRNA expression levels were detected by real-time PCR. Results Compared with LPL+ /-(W)mice, body weight of LPL+ /-(FB)mice was lowered, plasma TG and FFA levels were decreased by about 46.0% and 76.5% respectively, and fasting insulin level and HOMA-IR were decreased while there were no significant differences in fasting glucose level and AUCG between two groups. Insulin-stimulated Ser473 Akt phosphorylation levels in liver and skeletal muscle of LPL+ /-mice were enhanced by fenofibrate. ROS level in skeletal muscle of LPL+ /-(FB)mice was lower than that in LPL+ /-(W)mice while there was no significant difference in ROS of liver between two groups. Fenofibrate significantly increased SOD and CAT mRNA expressions in skeletal muscle of LPL+ /-mice, but not in liver. Conclusion Fenofibrate reduces body weight, ameliorates lipid metabolism, and improves insulin sensitivity in LPL+ /- mice, with reduced oxidative stress. (Chin J Endocrinol Metab, 2018, 34: 867-871) Key words: Lipoprotein lipase; Insulin resistance; Fenofibrate; Oxidative stress

Cholecystokinin is involved in triglyceride fatty acid uptake by rat adipose tissue.

The incorporation of plasma triglyceride (TG) fatty acids to white adipose tissue (WAT) depends on lipoprotein lipase (LPL), which is regulated by angiopoietin-like protein-4 (ANGPTL-4), an unfolding molecular chaperone that converts active LPL dimers into inactive monomers. The production of ANGPTL-4 is promoted by fasting and repressed by feeding. We hypothesized that the postprandial hormone cholecystokinin (CCK) facilitates the storage of dietary TG fatty acids in WAT by regulating the activity of the LPL/ANGPTL-4 axis and that it does so by acting directly on CCK receptors in adipocytes. We report that administration of CCK-8 (a bioactive fragment of CCK) to rats: (i) reduces plasma ANGTPL-4 levels; (ii) represses Angptl-4 expression in WAT and (iii) simultaneously enhances LPL activity in this tissue without inducing Lpl expression. In vivo CCK-8 effects are specifically antagonized by the CCK-2 receptor (CCK-2R) antagonist, L-365,260. Moreover, CCK-8 downregulates Angptl-4 expression in wild-type pre-adipocytes, an effect that is not observed in engineered pre-adipocytes lacking CCK-2R. These effects have functional consequences as CCK-8 was found to promote the uptake of dietary fatty acids by WAT, as demonstrated by means of proton nuclear magnetic resonance (1H-NMR). The efficacy of acute CCK-8 administration was not reduced after chronic CCK-8 treatment. Moreover, the effects of CCK-8 on WAT were not associated to the increase of circulating insulin. Our results show that cholecystokinin promotes lipid storage in WAT by acting on adipocyte CCK-2R, suggesting a pivotal role for CCK in TG homeostasis.

Abstract 26: Identification of a Novel Gene, DENND5B, Associated With Plasma High Density Lipoprotein Levels and Intestinal Fat Absorption

In an effort to identify novel high density lipoprotein (HDL) receptors expressed by the liver, a bacteriophage library expressing liver cDNA fragments was used to screen for clones that bind to HDL. The gene DENND5B showed significant enrichment for HDL binding over 3 cycles of biopanning, with negative selection against low density lipoprotein binding. Although little is known about the recently described DENN-domain containing family of proteins, some members act as guanine nucleotide exchange factors involved in the activation of Rab proteins and membrane trafficking. To examine the influence of DENND5B on HDL physiology, a DENND5B knockout mouse was generated using a custom zinc finger nuclease. DENND5B -/- mice had decreased plasma total cholesterol (-30.9%, p < 0.0001) and phosphatidylcholine (-31.4%, p < 0.0001). When plasma was analyzed by size-exclusion chromatography, the lipid effects were attributed entirely to decreased HDL. When fed western diet for 4 months, DENND5B -/- mice showed significantly smaller increases in plasma lipids and body weight compared to wild type mice. After sacrifice, DENND5B -/- mice were found to have a distended small intestine that was whitish in color. To evaluate fat absorption, mice were given an oral gavage of vegetable oil (10 uL/gram body weight) and plasma lipids were measured at 0, 2, and 4 hours post-gavage. DENND5B -/- mice had significantly reduced plasma triglyceride (p < 0.05) and free fatty acids (p < 0.01) in response to oil gavage compared to wild type mice. To identify a possible role for this gene in human lipoprotein metabolism, we examined gene expression data from 5,458 participants in the Framingham Heart Study. Consistent with the mouse data, a significant negative relationship exists between DENND5B expression and plasma HDL-C (p = 4.82 x 10 -5 ). In summary, using a phage display screening approach, we have identified a novel gene associated with circulating HDL levels in mice and humans. Additionally, in a homozygous knockout mouse model, a defect in intestinal fat absorption is present. Future studies will be aimed at evaluating the influence of this gene on HDL function, fat absorption, and atherosclerotic disease burden.

Treatment with CNX-011-67, a novel GPR40 agonist, delays onset and progression of diabetes and improves beta cell preservation and function in male ZDF rats

BackgroundThe role of G protein-coupled receptor (GPR40), which is highly expressed in pancreatic beta cells, has been studied extensively in the amelioration of beta cell dysfunction in T2D using rat and mouse islets, beta cell lines and in animal models of diabetes. But its potential as a therapeutic target has not been fully explored. This aim of the study is to evaluate the therapeutic potential of CNX-011-67, a highly selective, potent and orally bioavailable GPR40 agonist, in controlling diabetes and other metabolic parameters.MethodsSeven week old male ZDF rats were treated with either vehicle or CNX-011-67, 5 mg/kg twice daily, for seven weeks. The animals were subjected to oral glucose tolerance and insulin tolerance tests. Plasma glucose, insulin, triglyceride, HbA1c, fructosamine and free fatty acids were measured at selected time points. Pancreas from control and treated animals were subjected to insulin and pancreatic and duodenal homeobox 1 (PDX1) immunohistochemistry and were also evaluated by electron microscopy. Also the potential impact of CNX-011-67 on islet insulin secretion, content, ATP levels and markers of both glucose oxidation, beta cell health in rat islets under chronic glucolipotoxic conditions was evaluated.ResultsTreatment of male ZDF rats with CNX-011-67 for 7 weeks significantly enhanced insulin secretion in response to oral glucose load, delayed the onset of fasting hyperglycemia by 3 weeks, reduced nonfasting glucose excursions, fasting free fatty acids and triglyceride levels. A significant increase in PDX1 expression and insulin content and reduction in plasma fructosamine, HOMA-IR, and beta cell apoptosis were observed. CNX-011-67 improves glucose mediated insulin secretion, insulin gene transcription and islet insulin content in cultured rat islets under chronic glucolipotoxic condition. Also enhanced glucose oxidation in the form of increased islet ATP content and overall improvement in beta cell health in the form of reduced expression of stress markers (TXNIP and CHOP mRNA) were observed.ConclusionsThese findings, suggest that long-term oral therapy with CNX-011-67 could be of clinical value to provide good glycemic control and improve islet beta cell function.

Abstract 70: PPARdelta Agonist GW1516 Attenuates Diet-Induced Dyslipidemia, Insulin Resistance and Aortic Inflammation in Ldlr -/- Mice

Objective: The peroxisome proliferator-activated receptor (PPAR) delta has been implicated in systemic lipid homeostasis and inflammation. However, the role of PPARdelta agonists as anti-atherogenic agents remains unclear. In the present study, we used low-density lipoprotein receptor-null mice (Ldlr-/-) fed a high fat (HF) diet to test the hypothesis that a selective PPARdelta agonist corrects metabolic dysregulation and attenuates inflammation associated with atherosclerosis. Methods and Results: Ldlr -/- mice were fed chow or HF (42% fat, 0.2% cholesterol) for 4 weeks. Subsequently, the HF group was fed either HF or HF plus GW1516 (3mg/kg/d) for a further 8 weeks. Fasting plasma triglyceride, total cholesterol and free fatty acids were significantly decreased (-50%) by intervention with GW1516. In addition, GW1516 normalized fasting blood glucose and improved glucose and insulin tolerance. GW1516 also enhanced total energy expenditure compared to HF-fed mice. In the aorta, ER-stress markers CHOP and GRP78 were significantly elevated in HF-fed mice, which were markedly attenuated by GW1516-intervention. Aortae of HF-fed mice also showed marked elevations in the expression of proinflammatory cytokines including Ccl3, Il1beta, Icam1, Tnf, Il6 and Ccl2. Furthermore, HF-aortae, compared to chow, displayed reduced expression of the M2 macrophage marker arginase-1(Arg1). Intervention with GW1516 significantly attenuated aortic expression of all examined proinflammatory cytokines, and restored Arg1 expression. Enhanced MAPKerk signalling and decreased AKT/FoxO1 signalling are known to induce inflammatory cytokine expression in vitro. HF-feeding induced phosphorylation (p) of the MAP kinases ERK1/2 and p38 and dampened levels of pAKT and pFoxO1 in the aorta. In contrast, aortae of GW1516-treated animals displayed normalized levels of pERK1/2, p-p38, pAKT and pFoxO1. Conclusions: These studies demonstrate that PPARdelta activation ameliorates dyslipidemia and insulin resistance in HF-fed Ldlr -/- mice. Furthermore, PPARdelta activation inhibits aortic ER-stress as well as dysregulation of MAPK and AKT/FoxO1 signalling induced by HF-feeding, resulting in inhibition of the inflammatory response within the aorta.

High dietary sucrose triggers hyperinsulinemia, increases myocardial β-oxidation, reduces glycolytic flux and delays post-ischemic contractile recovery

Although the causal relationship between insulin resistance (IR) and hypertension is not fully resolved, the importance of IR in cardiovascular dysfunction is recognized. As IR may follow excess sucrose or fructose diet, the aim of this study was to test whether dietary starch substitution with sucrose results in myocardial dysfunction in energy substrate utilization and contractility during normoxic and post-ischemic conditions. Forty-eight male Wistar rats were randomly allocated to three diets, differing only in their starch to sucrose (S) ratio (13, 2 and 0 for the Low S, Middle S and High S groups, respectively), for 3 weeks. Developed pressure and rate x pressure product (RPP) were determined in Langendorff mode-perfused hearts. After 30 min stabilization, hearts were subjected to 25 min of total normothermic global ischemia, followed by 45-min reperfusion. Oxygen consumption, beta-oxidation rate (using 1-13C hexanoate and Isotopic Ratio Mass Spectrometry of CO2 produced in the coronary effluent) and flux of non-oxidative glycolysis were also evaluated. Although fasting plasma glucose levels were not affected by increased dietary sucrose, high sucrose intake resulted in increased plasma insulin levels, without significant rise in plasma triglyceride and free fatty acid concentrations. Sucrose-rich diet reduced pre-ischemic baseline measures of heart rate, RPP and non-oxidative glycolysis. During reperfusion, post-ischemic recovery of RPP was impaired in the Middle S and High S groups, as compared to Low S, mainly due to delayed recovery of developed pressure, which by 45 min of reperfusion eventually resumed levels matching Low S. At the start of reperfusion, delayed post-ischemic recovery of contractile function was accompanied by: (i) reduced lactate production; (ii) decreased lactate to pyruvate ratio; (iii) increased beta-oxidation; and (iv) depressed metabolic efficiency. In conclusion, sucrose rich-diet increased plasma insulin levels, in intact rat, and increased cardiac beta-oxidation and coronary flow-rate, but reduced glycolytic flux and contractility during normoxic baseline function of isolated perfused hearts. Sucrose rich-diet impaired early post-ischemic recovery of isolated heart cardiac mechanical function and further augmented cardiac beta-oxidation but reduced glycolytic and lactate flux.

Effects of insulin treatment on intracellular lipid metabolism in liver of diabetic rats

The effects and the mechanism of insulin treatment on intracellular lipid metabolism in liver of diabetic rats were evaluated. Type 2 diabetic rats were induced by injecting the streptozotocin (25 mg/kg) and fat rich food. According to the results of oral glucose tolerance test (OGTT) and glucose-induced insulin secretion test (IRT), the rats were divided into two groups: untreated group (UT) and insulin-treated group (IT). Normal rats (NC) served as controls. The treatment with either Humulin N (4--6 U/kg every day), or saline lasted for 4 weeks. Body weight, OGTT, IRT, blood lipids, intracellular lipids in liver, hepatic fatty acid oxidation and the activity of fatty acid synthase (FAS) were detected. The change of liver histology was observed. The insulin sensitivity index (ISI) was applied to assess the status of insulin resistance. The results showed that as compared with NC group, the plasma and hepatic intracellular Triglyceride (TG), total cholesterol (TC) and free fatty acids (FFAs) were increased significantly in UT group (P < 0.05), and lipid droplets could be seen dispersedly in the liver specimens, the hepatic fatty acid oxidation was increased markedly (P < 0.05), while the fatty acid synthase activity decreased (P < 0.05). Insulin treatment resulted in a further accumulation of lipids in liver by 55.7%, 19.87% and 22.2% increase in TG, TC, FFAs respectively. The size of hepatocytes was enlarged and the cells were filled with fat drops. Plasma lipids showed little decrease and still significantly higher than those in NC group after the insulin treatment. Meanwhile, insulin treatment was companied by 20% decrease in the rate of fatty acid oxidation and 31% increase in hepatic FAS activity compared to UT group. It was concluded that treatment with insulin on type 2 diabetic rat increases hepatic intracellular lipid accumulation by inhibiting hepatic fatty acid oxidation and activating FAS.

Pancreatic Islet Function in ω3 Fatty Acid-Depleted Rats: Glucose Metabolism and Nutrient-Stimulated Insulin Release

In order to gain information on the determinism of the perturbation of fuel homeostasis in situations characterized by a depletion in long-chain polyunsaturated omega3 fatty acids (omega3), the metabolic and hormonal status of omega3-depleted rats (second generation) was examined. When required, these rats were injected intravenously 120 min before sacrifice with a novel medium-chain triglyceride-fish oil emulsion able to provoke a rapid and sustained increase of the omega3 content in cell phospholipids. The measurement of plasma glucose, insulin, phospholipid, triglyceride, and unesterified fatty acid concentration indicated modest insulin resistance in the omega3-depleted rats. The plasma triglyceride and phospholipid concentrations were decreased in the omega3-depleted rats with abnormally low contribution of omega3 in both circulating and pancreatic islet lipids. The protein, insulin, and lipid content of the islets, as well as their intracellular and extracellular spaces, were little affected in the omega3-depleted rats. The metabolism of D-glucose in the islets of omega3-depleted rats was characterized by a lesser increase in D-[5-3H]glucose utilization and D-[U-14C]glucose oxidation in response to a given rise in hexose concentration and an abnormally low ratio between D-glucose oxidation and utilization. These abnormalities could be linked to an increased metabolism of endogenous fatty acids with resulting alteration of glucokinase kinetics. The release of insulin evoked by D-glucose, at a close-to-physiological concentration (8.3 mM), was increased in the omega3-depleted rats, this being considered as consistent with their insulin resistance. Relative to such a release, that evoked by a further rise in D-glucose concentration or by non-glucidic nutrients was abnormally high in omega3-depleted rats, and restored to a normal level after of the intravenous injection of the omega3-rich medium-chain triglyceride-fish oil emulsion. Because the latter procedure failed to correct the perturbation of D-glucose metabolism in the islets of omega3-depleted rats, it is proposed that the anomalies in the secretory behaviour of islets in terms of their response to an increase in hexose concentration or non-nutrient secretagogues is mainly attributable to alteration in K+ and Ca2+ handling, as indeed recently documented in separate experiments.

Quantitative trait loci for lipid metabolism in the study of OLETF x (OLETF x Fischer 344) backcross rats.

1. The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is a model of type II diabetes with accompanying dyslipidaemia and obesity. 2. To define chromosomal intervals associated with obesity (abdominal fat weight and plasma leptin levels), dyslipidaemia (plasma triglyceride, cholesterol and free fatty acids) and hyperglycaemia (plasma glucose levels), we have performed genome-wide quantitative traits loci (QTL) analyses of 115 male OLETF x (OLETF x Fischer 344) backcross animals at 16 weeks of age. 3. The Diabetes Mellitus OLETF type I (Dmo1) locus on rat chromosome 1 showed statistically significant involvement in elevations of plasma levels of triglycerides (P = 4.87 x 10(-6) at D1Rat90) and total cholesterol (P = 1.16 x 10(-5) at D1Rat306). 4. No other loci produced significant linkage to these observed phenotypes. 5. These analyses have confirmed the importance of Dmo1 in lipid homeostasis at younger ages as well as during overt diabetes, which appears later. Thus, alterations at the Dmo1 locus are a major risk factor for pathogenesis in the strain, a finding that agrees with physiological studies that indicate a role for dyslipidaemia in the type II diabetic syndrome of OLETF rats.

RELATIONSHIP OF ISOMERIC FATTY ACIDS IN HUMAN CORD BLOOD TO N3 AND N6 STATUS.† 1808

Trans isomers (t) and cis positional isomers (cp) of unsaturated fatty acids in the food supply are transferred from mother to fetus during pregnancy. Several European studies have found an inverse relationship between human fetal/preterm t and long chain n3 and n6 fatty acids derived from the essential fatty acids, which could have consequences for growth and neurodevelopment. We measured maternal (M) and cord blood (CB) plasma phospholipid (PL) and triglyceride (TG) fatty acids in 50 mother-term infant pairs. Plasma lipids were extracted, PL and TG separated, and fatty acid methyl esters (FAMES) prepared by standard procedures. FAMES were separated by capillary (SP-2560, 100 m × 0.25 mm) gas chromatography. M t intake(Harvard/Willett Food Frequency Questionnaire) correlated with MPL 18:1 t(n7-n11, g/100 g total fatty acids), which correlated with CBTG and CBPL 18:1 t (FASEB J 1996, in press). MPL 18:1 t and 18:1 cp (n5-n7) were also correlated (r=0.636, p<0.0001), and MPL 18:1 cp correlated with 18:1 cp in both CBTG (r=0.330, p<0.03) and CBPL (r=0.383, p<0.01). Having demonstrated relationships between M and CB 18:1 t and cp, we asked if these fatty acids in CB were related to CBPL docosahexaenoic acid (DHA, 22:6n3) and arachidonic acid (AA, 20:4n6). Both CBTG 18:1 t and cp were inversely related to CBPL DHA (r=-0.316, p<0.03 and r=-0.587, p<0.0001, respectively). CBTG 18:1 cp (but not t) was also inversely related to CBPL AA (r=-0.513, p<0.0001). Like CBTG 18:1 cp, CBPL 18:1 cp (but not t) was inversely correlated with CBPL AA (r=-0.498, p<0.0003) and CBPL DHA (r=-0.614, p<0.0001). Compared with t, cp may have been a more sensitive indicator of the inverse relationships between isomeric fatty acids and CBPL DHA and AA because cp was found in 3.6-fold (CBTG) and 6.3-fold (CBPL) higher amounts. On the basis of the relationships shown here, higher circulating M t and cp can be linked to poorer DHA and AA status at term birth, the consequences of which remain to be determined. Supported by Medical Student Research Fellowship Grant (USPHS GR DK07405).

Determination of plasma non-esterified fatty acids and triglyceride fatty acids by gas chromatography of their methyl esters after isolation by column chromatography on silica gel.

Non-esterified fatty acids (NEFA) and triglycerides were isolated from human plasma by column chromatography on silica gel. Eight principal fatty acids of each of these lipid classes were determined by gas chromatography of their methyl ester derivatives and quantified relative to multipoint standard curves. Within-day relative standard deviations for plasma non-esterified fatty acid and triglyceride fatty acid determinations were 2.4 and 3.2%, respectively. Day-to-day relative standard deviations for plasma non-esterified fatty acid and triglyceride fatty acid determinations were 1.4 and 1.1%, respectively. The total plasma concentration and the relative proportions of the eight non-esterified fatty acids determined by this method were significantly different from results obtained according to two generally accepted methods for direct plasma non-esterified fatty acid determination without a specific isolation step. These comparisons suggested that considerable fatty acid ester lipid hydrolysis occurred during these direct determination procedures, and that this hydrolysis resulted in 3-fold overestimation of plasma NEFA content by those methods. Measured levels of arachidonic acid are substantially overestimated by these direct determination methods in which non-esterified fatty acids are not isolated before derivatization.

Individual Responsiveness to a Cholesterol-Lowering Diet in Postmenopausal Women with Moderate Hypercholesterolemia

Background: The efficacy of the step 1 diet in outpatient women with hypercholesterolemia has been debated. Methods: Forty-one normotriglyceridemic women whose low-density lipoprotein (LDL) cholesterol levels were 3.62 to 5.17 mmol/L (140 to 200 mg/dL) participated in a twoperiod outpatient diet counseling study that used a 1-month high-fat, high-saturated fatty acid period (Hi-Sat diet) and a 4-month low-fat, low-saturated fatty acid period (step 1 diet). All women were postmenopausal and were not taking hormone replacement therapy. Levels of lipids, lipoproteins, and plasma triglyceride fatty acids were measured five times during the last 2 weeks of each dietary period. Dietary intake was assessed by 7-day food records. Results: The mean reduction in total cholesterol level achieved by the step 1 diet was 0.36 mmol/L (14 mg/ dL). The reduction in total cholesterol level was seen in both LDL cholesterol levels (0.28 mmol/L [11 mg/dL];P Conclusions: A step 1 diet lowers total and LDL cholesterol levels in postmenopausal women. A nonsignificant reduction in high-density lipoprotein cholesterol levels was also observed. Since some women achieved LDL cholesterol levels low enough to obviate the need for drug therapy as primary prevention of coronary heart disease, dietary therapy should remain the first step in the management of hypercholesterolemia in postmenopausal women. (Arch Intern Med. 1994;154:1977-1982)

Meal frequency influences circulating hormone levels but not lipogenesis rates in humans

To determine whether human lipogenesis is influenced by the frequency of meal consumption, 12 subjects were divided into two groups and fed isocaloric nutritionally adequate liquid diets over 3 days, either as three larger diurnal (n = 6) or as six small, evenly spaced (n = 6) meals per day. On day 2 (08:00 h) of each diet period, 0.7 g deuterium (D) oxide/kg body water was administered and blood was collected every 4 hours over 48 hours for measurement of plasma insulin and glucose-dependent insulinotropic polypeptide (GIP) levels. At each time point, the incorporation of D into plasma triglyceride fatty acid (TG-FA) was also determined by isotope ratio mass spectrometry after TG-FA extraction and combustion/reduction. Insulin and GIP levels were elevated over daytime periods in subjects fed three versus six meals per day. Contribution of de novo synthesis to total TG-FA production was not significantly different for days 2 and 3 in subjects consuming three (6.56% +/- 1.32% and 6.64% +/- 2.08%, respectively) and six (7.67% +/- 2.29% and 7.88% +/- 1.46%, respectively) meals per day. Net TG-FA synthesis rates over days 2 and 3 were 1.47 +/- 0.33 and 1.55 +/- 0.53 g/d, respectively, for subjects fed three meals per day, and 1.64 +/- 0.47 and 1.69 +/- 0.30 g/d for subjects fed six meals per day. These findings suggest that consuming fewer but larger daily meals is not accompanied by increases in TG-FA synthesis, despite the observation of hormonal peaks.

Individual Responsiveness to a Cholesterol-Lowering Diet in Postmenopausal Women With Moderate Hypercholesterolemia

The efficacy of the step 1 diet in outpatient women with hypercholesterolemia has been debated. Forty-one normotriglyceridemic women whose low-density lipoprotein (LDL) cholesterol levels were 3.62 to 5.17 mmol/L (140 to 200 mg/dL) participated in a two-period outpatient diet counseling study that used a 1-month high-fat, high-saturated fatty acid period (Hi-Sat diet) and a 4-month low-fat, low-saturated fatty acid period (step 1 diet). All women were postmenopausal and were not taking hormone replacement therapy. Levels of lipids, lipoproteins, and plasma triglyceride fatty acids were measured five times during the last 2 weeks of each dietary period. Dietary intake was assessed by 7-day food records. The mean reduction in total cholesterol level achieved by the step 1 diet was 0.36 mmol/L (14 mg/dL). The reduction in total cholesterol level was seen in both LDL cholesterol levels (0.28 mmol/L [11 mg/dL]; P < .005) and high-density lipoprotein cholesterol levels (0.08 mmol/L [3 mg/dL]; P = .08). Although individual LDL responsiveness to diet was normally distributed, there was marked variation in response, which could be explained only partially by compliance (change in saturated fat intake, 10%), change in body weight (3%), and an interaction between the palmitic acid content of the plasma and body weight (3%). A step 1 diet lowers total and LDL cholesterol levels in postmenopausal women. A nonsignificant reduction in high-density lipoprotein cholesterol levels was also observed. Since some women achieved LDL cholesterol levels low enough to obviate the need for drug therapy as primary prevention of coronary heart disease, dietary therapy should remain the first step in the management of hypercholesterolemia in postmenopausal women.

The effect of cimetidine in meal-stimulated gastric functions measured with a new method.

A new method to measure gastric functions after meal-stimulation without infusion of bicarbonate into the stomach is presented. Six healthy volunteers were investigated after stimulation of the gastric functions with a 300-ml fluid test meal with and without cimetidine infusion. Cimetidine reduced the acid output substantially but had no effect on gastric emptying.

Individual responses to a cholesterol-lowering diet in 50 men with moderate hypercholesterolemia

Dietary modification is the recommended first step in the treatment of hypercholesterolemia. However, the efficacy of the National Cholesterol Education Program Step 1 Diet in outpatients with hypercholesterolemia has been debated. Fifty normotriglyceridemic men whose ad libitum low-density lipoprotein (LDL) cholesterol levels were 4.14 to 5.69 mmol/L (160 to 220 mg/dL) participated in a two-period outpatient diet counseling study that used a 1-month high-fat, high-saturated fatty acid period (Hi-Sat) and a 4-month low-fat, low-saturated fatty acid period (Step 1 Diet). Lipid, lipoprotein levels, and plasma triglyceride fatty acids were measured five times during the last 2 weeks of each dietary period and averaged for each patient. Dietary intake was assessed by 7-day food records. During the Hi-Sat period, an LDL turnover study was done to determine the fractional catabolic rate of LDL. The mean reduction in total and LDL cholesterol levels achieved by diet was 0.54 mmol/L (21 mg/dL) and 0.39 mmol/L (15 mg/dL), respectively. These responses equaled those predicted from metabolic ward investigations. While dietary responsiveness was normally distributed, there was marked individual variation in response. The mean (+/- SD) for quartiles of LDL responsiveness were +0.41 +/- 0.21 mmol/L (+16 +/- 8 mg/dL), -0.16 +/- 0.13 mmol/L (-6 +/- 5 mg/dL), -0.57 +/- 0.16 mmol/L (-22 +/- 6 mg/dL), and -1.16 +/- 0.26 mmol/L (-45 +/- 10 mg/dL). These differences in response were partially explained by dietary adherence, baseline fractional catabolic rates of LDL, and the change in plasma triglyceride palmitate level. The Step 1 Diet is effective in lowering LDL cholesterol levels for many hypercholesterolemic men, and with appropriate counseling, outpatients can achieve results predicted by inpatient metabolic diet studies. Nonetheless, the responsiveness for individuals is highly variable, and this variability is influenced by both compliance and biologic factors. Since many men achieved LDL cholesterol levels low enough to remove the need for drug therapy in primary prevention for coronary heart disease, dietary therapy should remain the initial approach to the treatment of hypercholesterolemia.

Individual Responses to a Cholesterol-Lowering Diet in 50 Men With Moderate Hypercholesterolemia

<h3>Background:</h3> Dietary modification is the recommended first step in the treatment of hypercholesterolemia. However, the efficacy of the National Cholesterol Education Program Step 1 Diet in outpatients with hypercholesterolemia has been debated. <h3>Methods:</h3> Fifty normotriglyceridemic men whose ad libitum low-density lipoprotein (LDL) cholesterol levels were 4.14 to 5.69 mmol/L (160 to 220 mg/dL) participated in a two-period outpatient diet counseling study that used a 1-month high-fat, high—saturated fatty acid period (Hi-Sat) and a 4-month low-fat, low—saturated fatty acid period (Step 1 Diet). Lipid, lipoprotein levels, and plasma triglyceride fatty acids were measured five times during the last 2 weeks of each dietary period and averaged for each patient. Dietary intake was assessed by 7-day food records. During the Hi-Sat period, an LDL turnover study was done to determine the fractional catabolic rate of LDL. <h3>Results:</h3> The mean reduction in total and LDL cholesterol levels achieved by diet was 0.54 mmol/L (21 mg/ dL) and 0.39 mmol/L (15 mg/dL), respectively. These responses equaled those predicted from metabolic ward investigations. While dietary responsiveness was normally distributed, there was marked individual variation in response. The mean (±SD) for quartiles of LDL responsiveness were +0.41±0.21 mmol/L (+16±8 mg/dL), —0.16±0.13 mmol/L (—6±5 mg/dL), —0.57±0.16 mmol/L (—22±6 mg/dL), and —1.16±0.26 mmol/L (—45±10 mg/ dL). These differences in response were partially explained by dietary adherence, baseline fractional catabolic rates of LDL, and the change in plasma triglyceride palmitate level. <h3>Conclusions:</h3> The Step 1 Diet is effective in lowering LDL cholesterol levels for many hypercholesterolemic men, and with appropriate counseling, outpatients can achieve results predicted by inpatient metabolic diet studies. Nonetheless, the responsiveness for individuals is highly variable, and this variability is influenced by both compliance and biologic factors. Since many men achieved LDL cholesterol levels low enough to remove the need for drug therapy in primary prevention for coronary heart disease, dietary therapy should remain the initial approach to the treatment of hypercholesterolemia. (Arch Intern Med. 1994;154:317-325)

Lipid Tolerance Testing in Pregnancy

Macrosomia in the infant of the well-controlled diabetic mother suggests that a substrate other than glucose may influence fetal growth. We hypothesized that GDM alters lipid homeostasis during pregnancy. Our objective was to determine if an LTT could assist in identification of lipid abnormalities in the GDM individual. The LTT consisted of bolus infusion of 1.0 mg/kg 10% Intralipid (Cutter Vitrum, Berkeley, CA) followed by measurements of plasma glucose, insulin, glycerol, total triglycerides, and triglyceride fatty acids (18:1 and 18:2), total FFAs, and total phospholipids for 30 min before and 90 min after the bolus. The study groups were composed of 8 nonpregnant, nondiabetic subjects, 8 pregnant, nondiabetic subjects, 8 GDM patients receiving insulin, and 8 GDM patients who were diet controlled. Plasma glucose and plasma insulin concentrations did not change significantly after the bolus. No significant difference was noted in the K2 for glycerol of the nonpregnant, nondiabetic group compared with the pregnant groups. The K2 for total triglycerides, plasma triglyceride 18:1, and plasma triglyceride 18:2 indicated increased rates of disappearance of these substrates for the nonpregnant nondiabetic group compared with all pregnant groups. No significant differences were observed among the pregnant groups for any of these parameters. Pregnancy may be associated with a decreased rate of triglyceride lipolysis compared with nonpregnancy. No differences in lipid metabolism were noted among normal pregnant and relatively well-controlled GDM patients.

Measurement of human lipogenesis using deuterium incorporation.

In order to determine human triglyceride fatty acid (TG-FA) synthesis rates, the incorporation of deuterium from the plasma water pool in vivo into TG-FA was measured over 48 h in six healthy males under steady state conditions. Subjects consumed a nutritionally complete liquid diet as six evenly spaced small meals per day for 3 days and drank 0.7 g D2O/kg estimated body water, (99.8 APE) at 0800 h on day 2. D2O was added to the liquid diets to maintain plasma deuterium enrichment at plateau over days 2 and 3. Blood samples were obtained prior to dosing and every 4 h thereafter. Total TG-FA were obtained from plasma at each timepoint and combusted. The resultant water was vacuum-distilled into Zn-containing Pyrex tubes, reduced to hydrogen gas, and analyzed for deuterium abundance by isotope ratio mass spectrometry. TG-FA deuterium enrichment reached a plateau at approximately 12 h post-dose. To establish the amount of newly synthesized TG-FA in the total plasma TG-FA pool, two models were developed relating the maximum observed deuterium enrichment to the calculated theoretical maximum enrichment. In model A, it was assumed that TG-FA come solely from chylomicrons. This yields a value of 8.8 +/- 4.6 g/day (mean +/- SD) de novo synthesized TG-FA. On the opposite extreme in model B, it was assumed that all the TG-FA are derived from recycled very low density lipoprotein (VLDL); the amount of newly synthesized TG-FA calculated by this model was 1.7 +/- 0.8 g/day.(ABSTRACT TRUNCATED AT 250 WORDS)

Parenteral nutrition using MCT/LCT or LCT: Effect on the fatty acid composition of plasma triglycerides and platelet phospholipids

Plasma triglyceride fatty acids and platelet phospholipid fatty acids were compared in 20 malnourished patients before and after 8–10 days of total parenteral nutrition which included either a conventional lipid emulsion (LCT) or a new emulsion containing medium chain triglyercides (MCT/LCT). The use of both lipid emulsions altered the fatty acid profiles. The percentage of linoleic acid in the plasma triglycerides increased with both lipid emulsions, but more markedly with LCT. The median percentage after LCT was 25.9 (range 16.9–31.5) which was significantly higher (p < 0.01) than after MCT/LCT — 14.8 (range 6.1–20.2), or in healthy volunteers. After 8–10 days on MCT/LCT the fatty acid profile retained some features of the malnourished state, despite correction of the linoleic acid content. The percentage of linolenic and arachidonic acid in the platelet phospholipids tended to be lower than after LCT use, and the percentage of linoleic acid was significantly less (p < 0.01), the median (range) being 8.2 (4.5–23.8) after MCT/LCT and 11.7 (4.8–16.0) on LCT. Short term use of MCT/LCT emulsion may correct the fatty acid changes of malnutrition rather more slowly and results in a different fatty acid profile to that seen after LCT use. Whether this has any clinical effects is unclear.