Production of adipic acid by short- and long-chain fatty acid acyl-CoA oxidase engineered in yeast Candida tropicalis

In this study, to produce adipic acid, mutant strains of Candida tropicalis KCTC 7212 deficient of AOX genes encoding acyl-CoA oxidases which are important in the β-oxidation pathway were constructed. Production of adipic acid in the mutants from the most favorable substrate C12 methyl laurate was significantly increased. The highest level of production of adipic acid was obtained in the C. tropicalis ΔAOX4::AOX5 mutant of 339.8 mg L^-1 which was about 5.4-fold higher level compared to the parent strain. The C. tropicalis ΔAOX4::AOX5 mutant was subjected to fed-batch fermentation at optimized conditions of agitation rate of 1000 rpm, pH 5.0 and methyl laurate of 3% (w/v), giving the maximum level of adipic acid of 12.1 g L^-1 and production rate of 0.1 g L^-1 h^-1.

Analysis on the Substrate Specificity of Recombinant Human Acyl-CoA Synthetase ACSL4 Variants

Acyl-CoA synthetase long-chain family members (ACSLs) are a family of enzymes that convert long-chain free fatty acids into their acyl-CoAs. ACSL4 is an ACSL isozyme with a strong preference for arachidonic acid (AA) and has been hypothesized to modulate the metabolic fates of AA. There are two ACSL4 splice variants: ACSL4V1, which is the more abundant transcript, and ACSL4V2, which is believed to be restricted to the brain. In the present study, we expressed recombinant human ACSL4V1 and V2 in Spodoptera frugiperda 9 (Sf9) cells using the baculovirus expression system and then partially purified both variants by cobalt affinity column chromatography. We then established a novel ACSL assay system with LC-MS/MS, which is highly sensitive and applicable to various kinds of fatty acids, and used it to investigate the substrate specificity of recombinant human ACSL4V1 and V2. The results showed that both ACSL4 variants preferred various kinds of highly unsaturated fatty acids (HUFAs), including docosahexaenoic acid (DHA), adrenic acid (docosatetraenoic acid) and eicosapentaenoic acid (EPA), as well as AA as a substrate. Moreover, our kinetic studies revealed that the two variants had similar relative affinities for AA, EPA and DHA but different reaction rates for each HUFA. These results confirmed the importance of both of ACSL4 variants in the maintenance of membrane phospholipids bearing HUFAs. Structural analysis of these variants might reveal the molecular mechanism by which they maintain membrane phospholipids bearing HUFAs.

Acute Effects of Hibiscus Sabdariffa Calyces on Postprandial Blood Pressure, Vascular Function, Blood Lipids, Biomarkers of Insulin Resistance and Inflammation in Humans

Background/Objectives: The acute impact of Hibiscus sabdariffa calyces (HSC) extract on postprandial vascular function and other cardiometabolic risk factors have not been studied previously. This study investigated the acute impact of HSC extract consumption on blood pressure (BP), vascular function and other cardiometabolic risk markers. Subjects/Methods: Twenty-five men with 1% to 10% cardiovascular disease (CVD) risk (determined by QRISK^®2) were randomised to consume either 250 mL of the aqueous extract of HSC or water with breakfast in a randomised, controlled, single-blinded, 2-meal cross-over study (ClinicalTrials.gov, NTC02165553) with a two weeks washout period between study days. BP was measured at baseline and hourly for 4 h. Flow mediated dilatation (FMD) of the branchial artery was measured at baseline, 2 and 4 h post intervention drink consumption. Results: Acute consumption of aqueous extract of HSC caused a significant increase in % FMD (p < 0.001), a non-significant decrease in systolic BP (SBP) and diastolic BP (DBP); non-significant increase in urinary and plasma nitric oxide (NOx) and reduced response of serum glucose, plasma insulin, serum triacylglycerol and C-reactive protein (CRP) levels; significant (p = 0.026) improvement in the area under systemic antioxidant response curve (0 to 2 h); no significant changes in arterial stiffness following the acute consumption of the extract of HSC. Gallic acid, 4-O-methylgallic acid, 3-O-methylgallic acid and hippuric acid reached a maximum plasma concentration at 1 to 2 h post consumption of the extract of HSC. Conclusion: The extract of HSC improved postprandial vascular function and may be a useful dietary strategy to reduce endothelial dysfunction and CVD risk, although this requires confirmation.

The degree of acceptability of swine blood values at increasing levels of hemolysis evaluated through visual inspection versus automated quantification

The pronounced fragility that characterizes swine erythrocytes is likely to produce a variable degree of hemolysis during blood sampling, and the free hemoglobin may then unpredictably bias the quantification of several analytes. The aim of this study was to evaluate the degree of acceptability of values obtained for several biochemical parameters at different levels of hemolysis. Progressively increased degrees of physical hemolysis were induced in 3 aliquots of 30 nonhemolytic sera, and the relative effects on the test results were assessed. To define the level of hemolysis, we used both visual estimation (on a scale of 0 to 3+) and analytical assessment (hemolytic index) and identified the best analytical cutoff values for discriminating the visual levels of hemolysis. Hemolysis led to a variable and dose-dependent effect on the test results that was specific for each analyte tested. In mildly hemolyzed specimens, C-reactive protein, haptoglobin, β1-globulin, β2-globulin, α1-globulin, γ-globulin, sodium, calcium, and alkaline phosphatase were not significantly biased, whereas α2-globulin, albumin, urea, creatinine, glucose, total cholesterol, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, nonesterified fatty acids, bilirubin, phosphorus, magnesium, iron, zinc, copper, lipase, triglycerides, lactate dehydrogenase, unbound iron-binding capacity, and uric acid were significantly biased. Chloride and total protein were unbiased even in markedly hemolyzed samples. Analytical interference was hypothesized to be the main source of this bias, leading to a nonlinear trend that confirmed the difficulty in establishing reliable coefficients of correction for adjusting the test results.

Methylprednisolone Protects Cardiac Pumping Mechanics from Deteriorating in Lipopolysaccharide-Treated Rats

It has been shown that a prolonged low-dose corticosteroid treatment attenuates the severity of inflammation and the intensity and duration of organ system failure. In the present study, we determined whether low-dose methylprednisolone (a synthetic glucocorticoid) can protect male Wistar rats against cardiac pumping defects caused by lipopolysaccharide-induced chronic inflammation. For the induction of chronic inflammation, a slow-release ALZET osmotic pump was subcutaneously implanted to infuse lipopolysaccharide (1 mg kg(-1) d(-1)) for 2 weeks. The lipopolysaccharide-challenged rats were treated on a daily basis with intraperitoneal injection of methylprednisolone (5 mg kg(-1) d(-1)) for 2 weeks. Under conditions of anesthesia and open chest, we recorded left ventricular (LV) pressure and ascending aortic flow signals to calculate the maximal systolic elastance (E max) and the theoretical maximum flow (Q max), using the elastance-resistance model. Physically, E max reflects the contractility of the myocardium as an intact heart, whereas Q max has an inverse relationship with the LV internal resistance. Compared with the sham rats, the cardiodynamic condition was characterized by a decline in E max associated with the increased Q max in the lipopolysaccharide-treated rats. Methylprednisolone therapy increased E max, which suggests that the drug may have protected the contractile status from deteriorating in the inflamed heart. By contrast, methylprednisolone therapy considerably reduced Q max, indicating that the drug may have normalized the LV internal resistance. In parallel, the benefits of methylprednisolone on the LV systolic pumping mechanics were associated with the reduced cardiac levels of negative inotropic molecules such as peroxynitrite, malondialdehyde, and high-mobility group box 1 protein. Based on these data, we suggested that low-dose methylprednisolone might prevent lipopolysaccharide-induced decline in cardiac intrinsic contractility and LV internal resistance, possibly through its ability to reduce the aforementioned myocardial depressant substances. However, since our results were obtained in anesthetized open-chest rats, extrapolation to what may occur in conscious intact animals should be done with caution.

Prevention of arterial stiffening by using low-dose atorvastatin in diabetes is associated with decreased malondialdehyde

Introduction

Without affecting the lipid profile, a low-dose treatment with atorvastatin contributes to the reduction of oxidative stress, inflammation, and adverse cardiovascular events in diabetes. In this study, we investigated whether low-dose atorvastatin exerts any beneficial effect on vascular dynamics in streptozotocin (STZ)-induced diabetes in male Wistar rats.

Methods

Diabetes was induced using a single tail-vein injection of STZ at 55 mg kg⁻¹. The diabetic rats were treated daily with atorvastatin (10 mg kg⁻¹ by oral gavage) for 6 weeks. They were also compared with untreated age-matched diabetic controls. Arterial wave reflection was derived using the impulse response function of the filtered aortic input impedance spectra. A thiobarbituric acid reactive substances measurement was used to estimate the malondialdehyde content.

Results

The high plasma level of total cholesterol in the diabetic rats did not change in response to this low-dose treatment with atorvastatin. Atorvastatin resulted in a significant increase of 15.4% in wave transit time and a decrease of 33.5% in wave reflection factor, suggesting that atorvastatin may attenuate the diabetes-induced deterioration in systolic loads imposed on the heart. This was in parallel with its lowering of malondialdehyde content in plasma and aortic walls in diabetes. Atorvastatin therapy also prevented the diabetes-related cardiac hypertrophy, as evidenced by the diminished ratio of left ventricular weight to body weight.

Conclusion

These findings indicate that low-dose atorvastatin might protect diabetic vasculature against diabetes-associated deterioration in aorta stiffness and cardiac hypertrophy, possibly through its decrease of lipid oxidation-derived malondialdehyde.

Effects of acetyl-L-carnitine and oxfenicine on aorta stiffness in diabetic rats

BACKGROUND

We compared the haemodynamic and metabolic effects of acetyl-L-carnitine (one of the carnitine derivatives) and of oxfenicine (a carnitine palmitoyltransferase-1 inhibitor) in streptozotocin-induced diabetes in male Wistar rats.

MATERIALS AND METHODS

Diabetes was induced by a single tail vein injection of 55mgkg(-1) streptozotocin. The diabetic animals daily treated with either acetyl-L-carnitine (150mgkg(-1) in drinking water) or oxfenicine (150mgkg(-1) by oral gavage) for 8weeks,were compared with the untreated age-matched diabetic controls. Arterial wave reflection was derived using the impulse response function of the filtered aortic input impedance spectra. Thiobarbituric acid reactive substances (TBARS) measurement was used to estimate malondialdehyde (MDA) content.

RESULTS

Oxfenicine, but not acetyl-L-carnitine, increased total peripheral resistance in diabetes, which paralleled its elevation in plasma levels of free fatty acids. By contrast, acetyl-L-carnitine, but not oxfenicine, resulted in a significant increase in wave transit time and a decrease in wave reflection factor, suggesting that acetyl-L-carnitine may attenuate the diabetes-induced deterioration in systolic loading condition for the left ventricle. This was in parallel with its lowering of MDA/TBARS content in plasma and aortic walls in diabetes. Acetyl-L-carnitine therapy also prevented the diabetes-related cardiac hypertrophy, as evidenced by the reduction in ratio of the left ventricular weight to body weight.

CONCLUSION

 Acetyl-L-carnitine, but not oxfenicine, attenuates aortic stiffening and cardiac hypertrophy, possibly through its decrease of lipid oxidation-derived MDA/TBARS in the rats with insulin deficiency.

Potent anti-obesity effect of enteric-coated lactoferrin: decrease in visceral fat accumulation in Japanese men and women with abdominal obesity after 8-week administration of enteric-coated lactoferrin tablets

Lactoferrin (LF), a multifunctional glycoprotein in mammalian milk, is reported to exert a modulatory effect on lipid metabolism. The aim of the present study was to elucidate whether enteric-coated LF (eLF) might improve visceral fat-type obesity, an underlying cause of the metabolic syndrome. Using a double-blind, placebo-controlled design, Japanese men and women (n 26; aged 22-60 years) with abdominal obesity (BMI>25 kg/m2, and visceral fat area (VFA)>100 cm2) consumed eLF (300 mg/d as bovine LF) or placebo tablets for 8 weeks. Measurement of the total fat area, VFA and subcutaneous fat area from computed tomography images revealed a significant reduction in VFA ( - 14.6 cm2) in the eLF group, as compared with the placebo controls ( - 1.8 cm2; P = 0.009 by ANCOVA). Decreases in body weight, BMI and hip circumference in the eLF group ( - 1.5 kg, - 0.6 kg/m2, - 2.6 cm) were also found to be significantly greater than with the placebo (+1.0 kg, +0.3 kg/m2, - 0.2 cm; P = 0.032, 0.013, 0.041, respectively). There was also a tendency for a reduction in waist circumference in the eLF group ( - 4.4 cm) as compared with the placebo group ( - 0.9 cm; P = 0.073). No adverse effects of the eLF treatment were found with regard to blood lipid or biochemical parameters. From these results, eLF appears to be a promising agent for the control of visceral fat accumulation.

Carnitine deficiency aggravates carboplatin nephropathy through deterioration of energy status, oxidant/anti-oxidant balance, and inflammatory endocoids

We have recently shown that carnitine deficiency could represent a risk factor in paracetamol hepatotoxicity. By the same token, d-carnitine-induced carnitine deficiency aggravated carboplatin nephropathy following challenge with a single dose (35mg/kg, IP) of the platinum drug in male Swiss albino rats. The combination modality induced marked degenerative changes and severe inflammation in kidney tissues that surpassed either carboplatin or d-carnitine given alone. The combined regimen synergistically increased the serum levels of creatinine, blood urea nitrogen (BUN), tumor necrosis factor alpha (TNF-alpha), palmitate, and kidney malondialdehyde (MDA), adenosine triphosphate (ATP), nitric oxide (NO) contents as well as kidney myeloperoxidase (MPO) activity. The only parameter that has been notably decreased was the kidney reduced glutathione (GSH) level. Exaggeration by carnitine deficit of the deleterious effects of carboplatin is most probably ascribed to energy starvation. The reduction in kidney content of ATP parcels was associated with elevation of serum palmitate level that reflected debilitated fatty acid oxidation, and this further deteriorated energy resources in kidney tissues. Compromising the oxidant/anti-oxidant balance and modulating the release of some inflammatory endocoids namely, TNF-alpha and NO could also possibly account for such combinatorial detrimental toxicity. The current study was further extended to elucidate any possible nephroprotective effects of l-carnitine. Interestingly, carnitine supplementation ahead of carboplatin challenge ameliorated and almost normalized all the biochemical parameters and also mitigated the injurious effects of the cytotoxic drug. Thus, one could conclude that carnitine deficiency, whether being a causative clue or a sequela, might represent a risk factor in carboplatin nephropathy.

High-selenium yeast supplementation in free-living North American men: no effect on thyroid hormone metabolism or body composition

In a prior study, we observed decreased serum 3,3',5-triiodothyronine (T(3)), increased serum thyrotropin and increased body weight in five men fed 297 microg/d of selenium (Se) in foods naturally high in Se while confined in a metabolic research unit. In an attempt to replicate and confirm those observations, we conducted a randomized study of high-Se yeast supplements (300 microg/d) or placebo yeast administered to 42 healthy free-living men for 48 weeks. Serum thyroxine, T(3) and thyrotropin did not change in supplemented or control subjects. Body weight increased in both groups during the 48-week treatment period and remained elevated for the 48-week follow-up period. Body fat increased by 1.2 kg in both groups. Energy intake and voluntary activity levels were not different between the groups and remained unchanged during the treatment period. Dietary intakes of Se, macronutrients and micronutrients were not different between groups and remained unchanged during the treatment period. These results suggest that our previous observation of a hypothyroidal response to high-Se foods was confounded by some aspect of the particular foods used, or were merely chance observations. Because of the high dose and long administration period, the present study suggests that the effects of Se supplements on thyroid hormone metabolism and energy metabolism in healthy North American men with adequate Se status do not represent a significant risk for unhealthy weight gain.

N-ethylmaleimide-resistant acyl-coenzyme A oxidase from Arthrobacter ureafaciens NBRC 12140: molecular cloning, gene expression and characterization of the recombinant enzyme

N-ethylmaleimide (NEM)-resistant acyl-coenzyme A oxidase (ACO) has been desired for the determination of free fatty acids (FFAs). In order to meet this demand, we prepared recombinant ACO from Arthrobacter ureafaciens NBRC 12140. The coding region of the gene was 2109, encoding a protein of 703 amino acids with a predicted molecular mass of 76.5 kDa. The heterologous expression level in Escherichia coli was 520-fold higher than that in the native strain. The purified enzyme retained more than 60% activity after incubation in the presence of 10 mM NEM at 37 degrees C for 4 h, while other commercially available ACOs showed only less than 10% activities after the same NEM treatment. We presume that this is due to the presence of only three cysteines in ACO from A. ureafaciens. Site-directed mutagenesis studies and close scrutiny of the three-dimensional structures of other related ACOs suggested that these cysteines were buried in the protein and unreactive to NEM. The recombinant enzyme was used for the colorimetric determination of free fatty acid, which gave a linear calibration.

Evaluation of the hypolipemic property of Camellia sinensisVar. ptilophylla on postprandial hypertriglyceridemia

A naturally decaffeinated tea, Camellia sinensis var. ptilophylla (cocoa tea), has long been popular in southern China as a healthy beverage. Our experiments indicate that a single oral administration of 500 mg/kg of cocoa tea extract suppresses increases in plasma triacylgycerol (TG) levels when fed with 5 mL/kg of olive or lard oil in mice and that the inhibition rates are 22.9% and 31.5%, respectively, compared with controls. Under the same condition, cocoa tea extract did not affect the level of plasma free fatty acid. Likewise, the extract reduced the lymphatic absorption of lipids at 250 and 500 mg/kg. Also, cocoa tea extract and polyphenols isolated from cocoa tea inhibit pancreatic lipase. These findings suggest that cocoa tea has hypolipemic activity, which may be due to the suppression of digestive lipase activity by the polyphenols contained within the tea.

Micro method for determination of nonesterified fatty acid in whole blood obtained by fingertip puncture

Diagnostic tools for early identification of subjects at high risk for type 2 diabetes and other obesity-related disorders are important in prevention of these diseases. Nonesterified fatty acids (NEFAs) have been suggested to serve as a prediagnostic marker of diabetes and obesity-related disorders. In the current study, we developed a sensitive and reproducible micro method for quantification of NEFA in less than 10 microl whole blood. The method involves only two steps: (i) conversion of NEFA to fatty acid acyl-coenzyme A (acyl-CoA) esters using an acyl-CoA synthetase and (ii) quantification of the formed acyl-CoA esters with a fluorescent biosensor based on bovine acyl-CoA binding protein (ACBP). Lys50 of ACBP was mutagenized to a cysteine residue that was covalently modified with 6-bromoacetyl-2-dimethylaminonaphthalene to make a fluorescent acyl-CoA indicator (FACI-50). FACI-50 exhibits high fluorescence emission yield with maximum at 490 nm in the presence of CoA when excited at 387 nm. The addition of palmitoyl-CoA to a CoA-saturated FACI-50 lowered fluorescence emission by eightfold. Ethanol extract from 1 microl whole blood was incubated with ATP, CoA, and FACI-50. Following background fluorescence reading, NEFAs were converted to acyl-CoA by the acyl-CoA synthetase and the NEFA content was calculated from fluorescence emission changes using palmitic acid as external standard. The FACI-50 NEFA method was compared with two commercially available methods for quantification of NEFA.

BSB: a new mouse model of multigenic obesity

We report here a new mouse model of multigenic obesity. Backcross progeny ((C57BL/6J x Mus spretus)F1 x C57BL/6J), designated as BSB mice, range from 1% to 50% body fat. Since both parental strains are relatively lean, the wide range of the phenotype in the BSB mice indicates the involvement of multiple genes to produce obesity. Obesity in BSB mice results from increases in both intra-abdominal and subcutaneous fat and is associated with hyperinsulinemia, hyperglycemia, and hyperlipidemia. Female and male BSB mice do not differ in the degree of obesity obtained. Stimulated plasma corticosterone levels are reduced in obese male and female mice. The development of appropriate genetic markers and statistical methods have made it feasible to analyze quantitative polygenic traits in animal models by employing F2 or backcross progeny. Thus, this BSB model is uniquely suited to the genetic analysis of the multifactorial quantitative trait of obesity and its associated phenotypes.

Preference for safflower oil in rats exposed to a cold environment under free-feeding conditions

There are several benefits to a high-fat diet for animals exposed to cold, including improved tolerance to severe cold conditions and increased survival rates in cold environments. It is therefore of interest to examine whether animals exposed to cold will selectively consume lipids. We examined the intake of safflower oil (SO) by rats exposed to cold (4 +/- 2 degrees C) under a feeding condition in which the rats were given free access to SO. Rats exposed to cold consumed more SO than those housed at 25 +/- 2 degrees C. This finding suggests that rats prefer SO in a cold environment. There was no significant difference in the ratio of calories of SO ingested to that of matter (standard laboratory chow plus SO) ingested between rats exposed to cold and those at 25 +/- 2 degrees C. The high SO intake also affected cold tolerance and metabolite kinetics in the rats. Factors that affected the SO intake of rats exposed to cold are also discussed.

Cholesterol improves the utilization of parenteral lipid emulsions

Lipid emulsions have become an indispensable component of parenteral nutrition. Commercially available emulsions mostly have an identical composition of triglycerides (from plant oils) and egg-yolk phospholipids as emulsifier. Previous attempts to improve the composition of lipid emulsions have focused mainly on the triglyceride moiety. In the first fundamental modification of a lipid emulsion since their broader introduction into clinical medicine, we included free cholesterol in a lipid emulsion. We evaluated elimination and hydrolysis of triglycerides and lipid oxidation (by indirect calorimetry) in 10 healthy male normolipemic volunteers, comparing a conventional lipid emulsion (20% triglycerides) with an otherwise identical emulsion with the addition of 4 g/l free cholesterol. The rise in plasma triglycerides was mitigated during infusion of the cholesterol-enriched solution (323.8 +/- 27.5 vs. 202.0 +/- 18.9 mg.dL-1, p < 0.001), plasma half-life was reduced (41.6 +/- 5.4 vs. 29.3 +/- 5.1 min, p < 0.05), and total-body clearance was enhanced (0.96 +/- 0.1 vs. 1.52 +/- 0.2 ml.b.w.(.)min-1, p < 0.02). The rise in plasma free fatty acids (400.7 +/- 39.0 vs. 532.2 +/- 64.0 mumol.L-1; p < 0.02) and ketone bodies (beta-hydroxybutyrate) (151.6 +/- 37.0 vs. 226.3 +/- 33.01 mumol.L-1; p < 0.02) was augmented. Increases in plasma insulin and glucagon were less pronounced (p < 0.05). The fall in respiratory quotient was greater and the fraction of lipid oxidation as a percentage of total energy expenditure was increased (66.2% +/- 6.0 vs. 70.9% +/- 6.3, p < 0.05) during infusion of the modified solution. No impairment of gas exchange or other side effects were observed. Taken together these results indicate that the elimination of a cholesterol-supplemented lipid emulsion is accelerated, triglyceride hydrolysis is enhanced, and lipid oxidation is augmented. Thus, addition of cholesterol to a lipid emulsion might not only present a means of providing cholesterol in parenteral nutrition but also help to reshape artificial lipid particles to a more chylomicron-resembling composition and improve lipid utilization.

Hypertriglyceridemia associated with decreased post-heparin plasma hepatic triglyceride lipase activity in hypoxic rats

Exposure of sated rats to 45% N2 in air for 5h increased serum triglyceride levels by 212% over the levels in normoxic rats. This increase in triglyceride levels was accompanied by a decrease in plasma triglyceride hydrolase activity after intravenous injection of heparin. Further fractionation of the activity by inhibition of lipoprotein lipase indicated that the low triglyceride hydrolase activity is mainly due to a reduction in hepatic triglyceride lipase, which is inversely correlated with the serum triglyceride level. The hypoxic exposure decreased the arterial blood [acetoacetate]/[beta-hydroxybutyrate] ratio in the sated rats, which is believed to reflect the oxidation-reduction state in hepatic mitochondria, but did not affect the level of serum enzymes indicative of tissue damage. On the other hand, triglyceride levels did not change during hypoxic exposure in fasted rats. Thus, hypertriglyceridemia in sated rats following exposure to hypoxia may result from impaired removal of circulating triglycerides by hepatic triglyceride lipase located in the sinusoidal surface of the liver.

A randomized study over 13 cycles to assess the influence of oral contraceptives containing ethinylestradiol combined with drospirenone or desogestrel on carbohydrate metabolism

In this open-label, randomized study we compared the influence of a new oral contraceptive containing 30 microg ethinylestradiol and 3 mg drospirenone (Yasmin) with a reference preparation containing 30 microg ethinylestradiol and 150 microg desogestrel (Marvelon) on variables of carbohydrate metabolism by means of oral glucose tolerance tests at baseline and in the 6th and 13th treatment cycle. The mean levels of fasting glucose and insulin were similar at baseline and after 13 treatment cycles, whereas C-peptide and free fatty acid levels decreased slightly in both groups. All blood glucose and insulin values measured in the oral glucose tolerance tests were within normal ranges, despite a slight increase in the mean areas under the curves of 0-3 h [AUCs (0-3 h)] of both variables from baseline to treatment cycle 13. Differences between both treatments were not statistically significant. The mean AUCs (0-3 h) for C-peptide were not markedly changed in any treatment group. Free fatty acid levels decreased by 42% in the drospirenone group and increased by 48.9% in the desogestrel group, in terms of means of individual changes. Both preparations were well tolerated and equally efficacious regarding contraception and cycle control. The mean body weight was slightly decreased in most cycles during treatment with the drospirenone combination, as compared to baseline, while it was slightly increased versus baseline in all cycles during treatment with the desogestrel combination. The combination with drospirenone had less impact on blood pressure than the combination with desogestrel. In conclusion, Yasmin, a combined low-dose oral contraceptive with 30 microg ethinylestradiol and 3 mg of the novel progestogen drospirenone, as well as the reference Marvelon, containing 30 microg ethinylestradiol and 150 microg desogestrel had little impact on carbohydrate metabolism when used for 1 year. The observed changes were small and not suggestive of a clinically relevant deterioration of carbohydrate metabolism.

Hypolipemic effect of Cyclocarya paliurus (Batal) Iljinskaja in lipid-loaded mice

We investigated the inhibitory effect of Cyclocarya paliurus (Batal.) Iljinskaja (C. paliurus) extract on postprandial hyperlipemia in mice. A single oral administration of C. paliurus extract (250 mg/kg) suppressed an increase in plasma triacylgycerol (TG) levels when fed with 5 ml/kg of lard and olive oil. The inhibition rates were 28.6% and 24.1%, respectively, but free fatty acid (FFA) levels in plasma were not significantly affected as compared with control group mice. In addition, C. paliurus extract showed inhibitory activity toward pancreatic lipase, a key enzyme of dietary TG absorption, with an IC(50) of 9.1 microg/ml in vitro. Our results suggested that the hypolipemic action of C. paliurus extract was probably interrelated with suppression of the activity of digestive lipase, and as a result, the blood lipid level was reduced.

Effect of feeding on growth hormone response to growth hormone-releasing hormone in polycystic ovarian syndrome: relation with body weight and hyperinsulinism

The plasma growth hormone (GH) response to direct stimulation with growth hormone-releasing hormone (GHRH) before and after a standard meal was investigated in 14 polycystic ovarian syndrome (PCOS) subjects. Data were compared with those obtained from 14 healthy normovulatory matched patients. All women underwent an oral glucose tolerance test (OGTT) (75 g) and basal plasma hormone concentrations were evaluated. On a different day all subjects had a GHRH test (50 microg GHRH) both before and after lunch randomly. In obese PCOS subjects the GH response to GHRH was blunted after a meal, while in obese control patients there was an enhanced response of GH to GHRH after a meal. Normal control subjects showed an inhibition of the GH response after feeding and lean PCOS subjects showed a trend toward an augmented GHRH related secretion after a meal significantly higher than normal controls (P < 0.05) but not significantly higher than the pre-prandial response. In conclusion, the data indicate in PCOS a derangement of GH secretion related to food ingestion; in particular obese PCOS patients did not exhibit any change of GH response after a meal compared with the paradoxical response observed in obese controls. Several other factors beyond body mass index and hyperinsulinism could be involved in these pathophysiological events.

Determination of plasma free fatty acids by high-performance liquid chromatography with electrochemical detection

Determination of free fatty acids (FFAs) in control serum and human plasma was carried out by high-performance liquid chromatography with electrochemical detection. Peak height for palmitic, palmitoleic, stearic, oleic, linoleic, and arachidonic acids at a detection potential of -415 mV vs a saturated calomel electrode showed a linear relation to acid amount in the range 50-1600 pmol. The present method for plasma free fatty acid determination required only 10 microL of plasma sample. The method is simple and the time for blood pretreatment is short. Change in plasma FFA with blood glucose level was monitored before and after meal ingestion by this method, using one male and one female subject. It was possible to rapidly reduce plasma FFA and increase blood glucose subsequent to the meal. The present method is thus shown to have potential for clinical application.

Glucose-insulin relationships and thyroid status of cockerels selected for high or low residual food consumption

The plasma glucose-insulin relationships and thyroid status were investigated in two lines of adult cockerels divergently selected for high (R+) or low (R-) residual food consumption (RFC). For a given body weight, R+ birds had a 74% higher food intake than R- birds. Plasma glucose concentrations were significantly lower in the R+ line compared with the R- when fasted, whereas R+ birds exhibited a significantly lower plasma insulin concentration than R- birds either in fed or fasted state. After an overnight fast, R+ birds also exhibited a higher sensitivity to exogenous insulin in view of its more pronounced hypoglycaemic effect. After an oral glucose load, the glucose disposal of R+ cockerels was faster despite lower glucose-induced plasma insulin concentration. Whilst plasma triacylglycerol concentrations were lower in the R+ line when fed, plasma non-esterified fatty acid concentrations were higher in fasted R+ than R- cockerels (684 v. 522 mumol/l). Higher plasma triiodothyronine concentrations were observed in fed R+ compared with R- birds (3.0 v. 2.1 nmol/l respectively). The higher plasma concentrations of triiodothyronine associated with lower concentrations of insulin could account for the leanness and the elevated diet-induced thermogenesis previously observed in the R+ line.

No increased insulin sensitivity after a single intravenous administration of a recombinant human tumor necrosis factor receptor: Fc fusion protein in obese insulin-resistant patients

Inhibition of tumor necrosis factor (TNF)-alpha results in a marked increase in insulin sensitivity in obese rodents. We investigated the influence of a TNF antagonist [Ro 45-2081, a recombinant fusion protein that consists of the soluble TNF-receptor (p55) linked to the Fc portion of human IgG1] on insulin sensitivity of patients with android obesity. Seven patients (five women and two men; mean +/- SD age, 41 +/- 4 yr; body mass index, 36.1 +/- 4.7 kg/m2; waist to hip ratio, 0.99 +/- 0.11) were studied (three patients with normal glucose tolerance and four patients with impaired glucose tolerance or mild diabetes; all were hyperinsulinemic). Each patient underwent two consecutive euglycemic hyperinsulinemic glucose-clamp tests: 48 h after injection of placebo and 48 h after a single i.v. injection of 50 mg Ro 45-2081. In both tests, steady-state plasma glucose and insulin levels were similar. Insulin-mediated glucose disposal (2.23 +/- 0.74 vs. 2.38 +/- 0.99 mg/kg(-1) x min(-1)) and glucose metabolic clearance rate (2.28 +/- 0.85 vs. 2.48 +/- 1.03 mL/kg(-1) x min(-1)) were similar after placebo and after the drug. Indirect calorimetry showed no difference in substrate oxidation rates between the two experimental conditions. In conclusion, under the conditions of this study, no improvement in insulin sensitivity was observed in obese insulin-resistant patients following a single i.v. administration of a recombinant TNF receptor: Fc fusion protein.

Comparison of metabolic deterioration between insulin analog and regular insulin after a 5-hour interruption of a continuous subcutaneous insulin infusion in type 1 diabetic patients

An interruption of continuous sc insulin infusion (CSII) of the insulin analog lispro should result in a more rapid metabolic deterioration of type 1 diabetic patients because of its pharmacokinetic characteristics. We analyzed the metabolic changes occurring during a 5-h interruption of CSII and the 5 h after restarting the pump in 10 type 1 diabetic patients. The study was a randomized, cross-over, open label design comparing insulin analog [Lispro (LP)] and regular insulin [Velosuline (VE)]. Plasma glucose, free insulin, glucagon, betahydroxybutyrate (beta-OHB), and nonesterified fatty acids (NEFA) were measured every hour from 0700 h (time zero) to 1700 h (600 min). After stopping CSII, the plasma glucose level was significantly higher in the LP group than in the VE group (P < 0.05-0.01). The plasma free insulin level decreased significantly with the two treatments, but was significantly lower with LP than with VE (P < 0.05-0.01). Plasma NEFA increased more rapidly and was significantly higher in the LP group than in the VE group (P < 0.01-0.05). Plasma beta-OHB increased earlier with LP, but was not statistically different between the treatments. After restarting the pump, plasma glucose decreased with LP, but continued to increase with VE, and the plasma free insulin peak occurred earlier and was greater with LP than with VE (P < 0.05). Plasma NEFA and beta-OHB levels decreased significantly with the two treatments, but more dramatically with LP treatment. Thus, a short interruption of Lispro in CSII is associated with an earlier, greater metabolic deterioration, but Lispro corrected this metabolic deterioration more effectively.

Long-term effects of oral estradiol and dydrogesterone on carbohydrate metabolism in postmenopausal women

OBJECTIVE

To determine in postmenopausal women the long-term effects on carbohydrate metabolism of the administration of oral micronized 17 beta-estradiol (2 mg/day continuously) and cyclical dydrogesterone (10 mg/day for 14 days per 28-day cycle).

METHODS

A 2-year open-label prospective, non-comparative study was carried out of 13 healthy postmenopausal women receiving cyclical estradiol and dydrogesterone and serving as their own controls. Concentrations of blood glucose, plasma insulin, C-peptide, glucagon and free fatty acids (FFAs) were determined before treatment (base-line) and at 6, 12 and 24 months of hormone replacement therapy under fasting conditions and during a standard 75-g, 3-h, oral glucose tolerance test (OGTT).

RESULTS

Fasting blood glucose levels were unchanged throughout the study, and the mean areas under the curves (AUCs) for glucose response increased slightly but non-significantly versus baseline; fasting plasma insulin levels tended a decrease, and AUCs for insulin responses to the glucose load fell by 23% from baseline (not significant); fasting C-peptide levels and AUCs were unchanged; plasma glucagon fasting levels and responses were in the normal range and stable throughout the study; and plasma FFA fasting levels decreased significantly, as well as FFA AUCs during OGTTs, at the 12th and 24th months of the study.

CONCLUSIONS

During a 2-year treatment with oral estradiol and cyclical dydrogesterone, a direct progesterone derivative, tolerance to glucose was unchanged, fasting plasma insulin and insulin response to repeated glucose loads were decreased, and C-peptide levels remained unchanged, indicating a potential improvement in insulin sensitivity and clearance, as in younger women; additionally, a slightly enhanced antilipolytic activity of insulin was observed.

Blood lipid profile in ischaemia reperfusion injury

BACKGROUND

Lipid components are considered to play an important role in ischaemia reperfusion injury although the mechanism of their action remains unknown. Accumulation of lipid metabolites in ischaemic tissues is a consistent observation, but exactly how these lipids are cleared from the tissues by the circulating blood during reperfusion is still open to speculation. In the present study, levels of blood lipids (fatty acids, phospholipids, triglycerides, cholesterol, lysolecithin and lysolecithin platelet activating factor (lyso PAF)) and the enzyme phospholipase A2 were determined in an experimental animal model (dogs) of ischaemic reperfusion injury.

METHODS

The injury was induced by 4 h of aortic clamping followed by 2 h of reperfusion (unclamping). Blood samples were collected before clamping and at predetermined time intervals (0, 15, 60 and 120 min) after the release of clamp. The lipid contents were analysed and compared with sham-treated control dogs.

RESULTS

The results showed significantly elevated levels of triglycerides and phospholipase A2, during ischaemia and reperfusion in experimental animals indicating tissue damage in the ischaemic phase continuing into the reperfusion phase and the risk of systemic damage from these toxic substances. Total fatty acid content in the circulating blood showed decreasing trends during the same time interval, which suggested possible reduced clearance of accumulated fatty acids from the affected tissues. Serum cholesterol, phospholipids, lyso PAF and lysolecithin did not show any significant variation compared with control dogs.

CONCLUSIONS

It is possible that the delayed clearance of fatty acids may be due to the presence of fatty acids binding proteins in the ischaemic tissue, which trap these fatty acids in the tissues during ischaemic reperfusion injury. The prolonged retention of the accumulated fatty acids in the tissues in association with elevated triglycerides and phospholipase A2 activity may contribute to ischaemia reperfusion injury.

Effect of carbohydrate ingestion on sprint performance following continuous and intermittent exercise

PURPOSE

This investigation was conducted to study the effects on sprint performance of glucose and fructose ingestion during a 15-min rest period half way through 90 min of continuous and intermittent exercise. On three occasions, eight subjects cycled at 76 +/- 2% VO2max for 90 min (continuous trials: CON trials) with a 15-min half-time break.

METHODS

On another three occasions, they cycled for 90 min between moderate (65% VO2max) and high (100% VO2max) intensity (intermittent trials: INT trials) with the same half-time. In both trials, 90-min exercise was followed by a 40-s Wingate test to evaluate remaining sprint capacity. During half-time, they consumed either 20% glucose polymer (G), 20% fructose (F) or sweet placebo (P). Ingestion of G maintained plasma glucose levels, carbohydrate oxidation rate and lower value of ratings of perceived exertion (RPE) in both trials and indicated higher sprint performance compared with P (mean power of CON trials: 614.3 +/- 23.3 W vs 574.0 +/- 22.7 W, P < 0.001, INT trials: 629.5 +/- 27.6 W vs 596.3 +/- 25.5 W, P < 0.01).

RESULTS

Ingestion of F showed similar effect in CON trials (603.8 +/- 26.1 W vs 574.0 +/- 22.7 W, P < 0.01) but had no positive effect in INT trials. Additionally, mean power of G was higher than F (629.5 +/- 27.6 W vs 598.4 +/- 34.2 W, P < 0.01) in INT trials.

CONCLUSIONS

These results indicated that ingestion of G during half-time of 90-min exercise could maintain carbohydrate utilization and improve sprint performance in both CON and INT trials.

Use of intravenous lipids in critically ill patients with sepsis without and with hepatic failure

BACKGROUND

Fat is the preferred energy fuel both in patients with sepsis and with hepatic failure. Thus lipid emulsions should serve as an ideal nutritional substrate in parenteral nutrition. However, previous studies have generated conflicting results on the utilization of artificial lipids in these disease states, and systematic studies in critically ill patients with combined organ dysfunctions and additional complications are lacking. We compared the elimination, hydrolysis, and oxidation of a 20% lipid emulsion in critically ill patients on respiratory support with sepsis and with sepsis plus hepatic failure and in healthy control subjects.

SETTING

Medical critical care unit of a university hospital.

SUBJECTS AND METHODS

Eight critically ill patients with sepsis, 8 patients with sepsis and decompensated chronic hepatic failure, and 10 healthy volunteers were investigated. Elimination and hydrolysis was evaluated during constant i.v. infusion of 4.5 mg.kg body wt-1.min-1 of triglycerides during 120 minutes. Concentrations of plasma triglycerides, free fatty acids, and glycerol were measured, and elimination parameters were analyzed from plasma curves of triglycerides by using a two-compartment model. Resting energy expenditure and substrate oxidation were measured by indirect calorimetry.

RESULTS

In patients with sepsis without and with hepatic failure the rise in plasma triglycerides was blunted and the clearance of triglycerides was enhanced by 20% and 40% (p < .05), respectively, compared with healthy controls. Basal free fatty acid concentrations were elevated, and the rise of free fatty acids and glycerol was comparable to healthy subjects. Energy expenditure was increased and lipid oxidation (as fraction of total energy expenditure) was slightly elevated in both patient groups; the rise in lipid oxidation during lipid infusion was comparable to controls. No side effects or impairment of gas exchange was seen.

CONCLUSIONS

In a clinically relevant dosage range, the utilization of an i.v. lipid emulsion, the elimination and hydrolysis of triglycerides, and the lipid oxidation is not impaired in ventilated critically ill patients with sepsis or sepsis and chronic hepatic failure. Lipid emulsions thus are efficiently metabolized in critically ill patients with combined organ dysfunctions and associated sepsis.

Effect of elevated blood FFA levels on endurance performance after a single fat meal ingestion

PURPOSE

This study was designed to examine the effect of elevated blood free fatty acid (FFA) levels on carbohydrate (CHO) oxidation and cycling performance after ingesting a single fat meal (FM).

METHODS

Four hours before cycling exercise, nine trained males consumed either a FM (4711 kJ; 30% CHO, 61% fat, and 9% protein) or control meal (CM) (4877 kJ; 58% CHO, 31% fat, and 11% protein). The intensity of exercise employed was 67% of the maximal oxygen consumption (VO2max) for the first 120 min of exercise, followed by an increase to 78% VO2max.

RESULTS

The FM ingestion significantly (P < 0.05 and P < 0.01) elevated serum FFA levels above those resulting from CM ingestion almost throughout the entire exercise. A significantly (P < 0.05 and P < 0.01) lower respiratory exchange ratio in the FM versus the CM trials was observed during the first hour of exercise. This was accompanied by a significantly greater amount of fat oxidized at 20 (P < 0.01) and 60 min (P < 0.05) of FM trials and a significantly smaller amount of CHO oxidized at 20 min (P < 0.05) of FM trials. However, endurance time and work production did not differ between the FM (141 +/- 8 min, 134333 +/- 6049 kg x m (SEM)) and CM (138 +/- 5 min, 131450 +/- 4737 kg x m) trials. Also, there were no significant differences in oxygen consumption, heart rate, and perceived exertion or in glucose, lactate, and triglyceride levels in the blood.

CONCLUSIONS

These results suggest that the elevated blood FFA levels after a single FM ingestion reduce CHO oxidation early in exercise, but this decrease in CHO oxidation would not be adequate enough to contribute to an increased endurance.

An enzymatic method for the determination of free fatty acids in serum/plasma

Estimation of serum free fatty acids (FFA) in serum based on the formation of inorganic phosphate has been simplified by eliminating complex stages. The principle of the present method is based on breakdown of pyrophosphate, formed by thioesterification of free fatty acids with ATP and CoA with the aid of acyl-CoA synthetase (EC 6.2.1.3) to inorganic phosphate. This is measured using the reaction with molybdate. The reaction equations are as follows: [formula: see text] The recovery of free fatty acids was 96%. The interferences of citrate, phosphatidylserine, succinate, ascorbic acid and lecithin were between 0.5 and 2%. The correlation between the new enzymatic and the classic enzymatic method was 0.966. The lower detection limit was 0.018 mmol/l. The method was linear between 0.02 and 2.0 mmol/l. The within-assay and between-assay imprecision (CV) of control sera was 5.5% and 8%, respectively.

Cellular uptake of stearic, oleic, linoleic, and linolenic acid and their effects on synthesis and secretion of lipids in Hep-G2 cells

The present study was undertaken to examine the cellular uptake of stearic (18:0), oleic (18:1), linoleic (18:2), and linolenic acid (18:3), and their effects on synthesis and secretion of lipids in Hep-G2 cells. The cells were grown for 6 days in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum. On day 7, cells were incubated in a serum-free DMEM containing 0.25-1.0 mM of 18:0, 18:1, 18:2 or 18:3. The cellular uptake of these fatty acids was almost linear during the 4 hr incubation period, and no significant differences were noted among the fatty acids tested, regardless of their degree of unsaturation. The treatment of cells with 1.0 mM of these fatty acids stimulated triglyceride (TG) synthesis nearly ten-fold and phospholipid (PL) synthesis approx, two-fold compared with those of the control. The lipoprotein-TG secretion also increased and was the highest with 18:1 followed in descending order by 18:2, 18:3, and 18:0. The fatty acid treatment of cells also significantly increased the incorporation of 14C-acetate into the cellular and lipoprotein cholesterol compared with that of the control (p < 0.05). In addition, notable changes occurred in the fatty acid composition of cellular and medium lipids, which were enriched with the particular fatty acid present in the incubation medium. The findings that 18:0, 18:1, 18:2, and 18:3 were taken up by Hep-G2 cells at almost identical rates demonstrate that differences in the cellular synthesis of lipids and their secretion are attributable to the metabolic specificity of those fatty acids, rather than variable rates of their uptake.

Diet-induced thermogenesis in cockerels is modulated by genetic selection for high or low residual feed intake

Energy balance of adult cockerels genetically selected for high (R+) or low (R-) residual feed consumption was investigated by using indirect calorimetry. Although no between-line difference was found in digestion of ingested energy, the true metabolizable energy (ME) intake was 40% greater in R+ than in R- birds. Basal heat production (HP) did not significantly differ between genotypes. Diet-induced thermogenesis (DIT) was significantly enhanced in R+ compared with R- birds, i.e., +84% when expressed as the difference in kilojoules of heat production determined in feed-deprived and fed cockerels, +31% when calculated as a percentage of ME intake (P < 0.01). The difference in DIT calculated from the regression between HP and physical activity explained 75% of the difference in HP; the remaining 25% could be explained by activity-related HP. The results cannot be explained by differences in the plasma concentration of circulating thyroid hormones: plasma thyroxine concentration did not differ between genotypes, whereas plasma triiodothyronine concentration was lower in feed-deprived R+ than in R- birds and indistinguishable in fed birds of the two lines. Heat production, however, was higher in the R+ line. Propranolol decreased HP only in the R+ line, suggesting a beta-adrenergic control of DIT at least in cockerels of this line. Plasma triglyceride concentration was lower in the R+ than in the R- line in fed cockerels, and plasma nonesterified fatty acid concentration was higher in the R+ than in the R- line in feed-deprived cockerels. These results are consistent with the leanness of the R+ compared with the R- line. The R+ and R- lines constitute an original model of diet-induced thermogenesis (DIT), a process that is under genetic control of appetite and allows R+ birds to balance all of their excessive energy intake without any adipose tissue storage.

Effect of calcium soaps of fatty acids and administration of somatotropin in early lactation on productive and reproductive performance of high producing dairy cows

This study examined the mechanisms by which calcium soaps of fatty acids and bovine somatotropin (bST) affect production and reproduction of high producing cows. Calcium soaps of fatty acids were fed at 2.2% dry matter, and 500 mg of Zn-sometribove (Monsanto Inc., St Louis, MO) were injected subcutaneously every 14 d from 10 to 150 d in milk (DIM). Production of fat-corrected milk was increased by 3.5 kg/d when calcium soaps of fatty acids were fed, by 6.1 kg/d when bST was administered, and by 7.4 kg/d when calcium soaps of fatty acids were fed and bST was administered. Body weight was similar for cows on all treatments until 85 DIM after which cows that were treated with bST had lower body weights. Body condition scores decreased more for cows treated with bST and began increasing later and more slowly. Treatment with bST resulted in more cows that experienced first ovulation after 30 DIM, and more cows on the control treatment exhibited first estrus before 35 DIM. Days open were greater when bST was administered. After the first artificial insemination, conception rates were similar for cows on the control treatment and for cows fed calcium soaps of fatty acids; conception rates after the first artificial insemination were low for all cows treated with bST. Pregnancy rates at 120 and 150 DIM were decreased by bST. Number of DIM to first ovulation, number of DIM to first estrus, and days open were negatively correlated with glucose and cholesterol concentrations in plasma. Production of fat-corrected milk was correlated with days open and with concentrations of triglycerides in plasma, nonesterified fatty acids, and cholesterol. Increased production had different effects on reproduction when induced by calcium soaps of fatty acids or bST treatment. Some of the adverse effects of bST treatments were alleviated by calcium soaps of fatty acids.

Acylcarnitine removal in a patient with acyl-CoA beta-oxidation deficiency disorder: effect of L-carnitine therapy and starvation

Carnitine levels and acylcarnitine profiles in a patient with mild multiple acyl-CoA dehydrogenase deficient beta-oxidation were compared with control results. Whereas blood and urine total carnitine levels were moderately decreased, blood esterified carnitine levels in the patient were about 2-fold higher than in controls. Urinary acylcarnitine profiles presented with a larger variety of carnitine esters than in controls and included propionylcarnitine, butyrylcarnitine, 2-methylbutyrylcarnitine, hexanoylcarnitine and octanolycarnitine. Total carnitine levels in body fluids were similarly affected by chronic oral L-carnitine administration in patient and controls. By contrast, esterified carnitine level increase was 2-fold more important in controls than in patient. Whereas no qualitative changes in urinary acylcarnitine profiles were induced by L-carnitine therapy in controls, several alterations of these profiles were observed in the patient. The effect of starvation on metabolites was also studied, especially beta-oxidation rates assessed by free fatty acids to 3-hydroxybutyric acid ratios in blood from the patient in the untreated and L-carnitine treated states. In the L-carnitine-supplemented patient, the effect of starvation on the time course of carnitine levels and acylcarnitine profiles could also be documented. The ability of chronic oral L-carnitine administration to remove relatively less important amounts of acylcarnitines in the patient than in controls is further discussed, as well as qualitative alterations of acylcarnitine profiles induced by this therapy in the pathological condition.

A lack of direct action of glucagon on kidney metabolism, hemodynamics, and renal sodium handling in the dog

Although several reports suggest that pharmacologic amounts of glucagon may promote natriuresis, the influence of a physiological or even pathophysiological increase in circulating glucagon levels on kidney function has never been convincingly demonstrated. The present study was therefore undertaken to determine whether a moderate increase in plasma glucagon concentration of blood perfusing the kidney may influence kidney function and promote urinary sodium excretion. To this end, glucagon was infused directly into one renal artery of anesthetized dogs at a rate of 1 ng x kg(-1) x min(-1), calculated to increase glucagon concentration in the blood perfusing the kidney within the pathophysiologic range and thus to levels seen in some catabolic states such as poorly controlled diabetes or starvation. The contralateral kidney was infused with saline only. The estimated concentration of glucagon in blood perfusing the hormone-infused kidney increased with glucagon infusion from 227 pg x mL(-1) during the control period to mean of 779 pg x mL(-1). There was a significant increase in glucagon extraction by this kidney, from 33% in baseline conditions to 61% upon intrarenal infusion of the hormone, and hence venous glucagon levels were only slightly higher than in the contralateral kidney. Despite a more than threefold increase in glucagon levels in blood perfusing the hormone-infused kidney versus the contralateral kidney, this experimentally induced hyperglucagonemia was without influence on renal plasma flow (RFP), glomerular filtration rate (GFR), renal vascular resistance, renal uptake of oxygen and energy-providing substrates. Excretion of Na+, K+, Cl-, and PO4(3-) was likewise unaffected. These results indicate that hyperglucagonemia, at least of a magnitude comparable to that seen in starvation or diabetic decompensation, is devoid of any detectable direct influence on renal hemodynamics or tubular function.

Metabolic and endocrine changes induced by chronic heatexposure in broiler chickens : biological and endocrinological variables

Abstract:

The present study was designed to investigate the effect of chronic heat exposure (32° constant) on plasma metabolites and hormone concentrations in broiler chickens. At 2 and 4 weeks of age, fifty-four male Shaver broiler chickens were allocated to one of three treatments: 22° ad lib. feeding (22AL), 32°ad lib. feeding (32AL) and 22°,pair-feeding with the 32AL group (22PF). Ambient temperature was kept constant at either 22 or 32° for 2 weeks. Plasma glucose, triacylglycerols, phospholipids, non-esterified fatty acids (NEFA), individual amino acids, uric acid, insulin, triiodothyronine (T3), thyroxine, corticosterone were determined. Sensitivity to exogenous insulin was also measured at 7 weeks of age. At 4 and 6 weeks of age, i.e. after 2 weeks at high ambient temperature, fasted 32AL chickens displayed similar concentrations of glucose and triacylglycerols to those of 22AL birds. When fed, 32AL chickens exhibited higher plasma levels of glucose and decreased concentrations of NEFAand amino acids. Feed restriction resulted in intermediate values. Concentrations of all plasmafree amino acids were decreased under heat exposure except for aspartic acid, glutamic acid andphenylalanine. At 6 weeks of age, plasma T3 was reduced irrespective of the nutritional state, while plasma corticosterone concentrations were increased in 32AL birds compared with 22AL birds. Heat exposure did not change plasma insulin concentration in either fasted or fed chickens. The 32AL chickens displayed significantly reduced sensitivity to exogenous insulin when fasted,but an enhanced response to insulin when fed, compared with both 22° groups. Such endocrinological changes could stimulate lipid accumulation through increased de novo lipogenesis, reduced lipolysis and enhanced amino acid catabolism under chronic heat exposure.

Short administration of metformin improves insulin sensitivity in android obese subjects with impaired glucose tolerance

In a double-blind, randomized, cross-over study, the metabolic effects of a short treatment with metformin (2 x 850 mg day-1 for 2 days and 850 mg 1 h before evaluation) were compared to those of placebo in 15 obese subjects (BMI: 33.2 +/- 0.9 kg m-2), with abdominal distribution of adipose tissue and impaired glucose tolerance. An intravenous glucose tolerance test (0.3 g glucose kg-1) was performed after each period of treatment. Areas under the curve (AUC0-180 min) were calculated for plasma glucose, insulin, and C-peptide levels. Glucose tolerance was estimated by the coefficient of glucose assimilation (KG). Insulin sensitivity (SI) and glucose effectiveness (SG) indices were calculated using Bergman's minimal model. Insulin secretion rate (ISR) was determined by deconvolution of plasma C-peptide levels and insulin metabolic clearance rate (MCR) was estimated by dividing AUC 1SR by AUC insulin. Fasting plasma insulin levels were reduced after metformin (89.3 +/- 15.9 vs 112.4 +/- 24.3 pmol l-1; p = 0.04). AUC glucose, KG and SG were similar in both tests. However, AUC insulin was reduced (39.7 +/- 6.5 vs 51.8 +/- 10.4 nmol min l-1; p = 0.02), while SI (6.98 +/- 1.14 vs 4.61 +/- 0.42 10(-5) min-1 pmol-1 l; p = 0.03) and insulin MCR (715 +/- 116 vs 617 +/- 94 ml min-1 m-2; p = 0.03) were increased after metformin. The demonstration that metformin rapidly improves insulin sensitivity should encourage further research to evaluate the long-term effects of metformin in android obese subjects with impaired oral glucose tolerance.

Unique cholesteryl glucosides in Helicobacter pylori: composition and structural analysis

A chloroform-methanol-extracted lipid of Helicobacter pylori was studied. Three kinds of glycolipids, accounting for about 25% (wt/wt) of the total lipid, were detected and identified to be cholesteryl glucosides. The structures of two of them were determined to be cholesteryl-alpha-D-glucopyranoside and cholesteryl-6-O-tetrade-canoyl-alpha-D-glucopyranoside, and the plausible structure of the third one was identified as cholesteryl-6-O-phosphatidyl-alpha-D-glucopyranoside. Cholesteryl glucosides are very rare in animals and bacteria. Furthermore, those in H. pylori had an alpha-glycosidic linkage, which is rather unusual for natural glycosides, and a phosphate-linked cholesteryl glycoside like the cholesteryl-6-O-phosphatidyl-alpha-D-glucopyranoside has not been reported previously. As the cholesterol glucosides were detected in strains obtained from diverse geographical locations, the presence of cholesteryl glucosides in H. pylori is a very unique and a characteristic feature of the species. These findings add a new facet to the physiology and biochemistry, especially the cholesterol and glucose metabolism, of H. pylori. Furthermore, the cholesteryl glucosides of H. pylori showed hemolytic activities.

Comparison of the effects of a range of dietary lipids upon serum and tissue lipid composition in the rat

Since the type of fat consumed in the diet may play a role in the development of several disorders, it is important to ascertain the effects of different dietary fats upon parameters such as serum lipid levels and adipose deposition. The aim of this study was to determine the effects of feeding rats a range of fats with differing fatty acid compositions. Weanling male rats were fed for 10 weeks on a low fat (LF) diet or on one of five high fat diets, which contained 20% by weight of either hydrogenated coconut oil (HCO), olive oil (OO), safflower oil (SO), evening primrose oil (EPO) or menhaden (fish) oil (MO). Food intake, animal growth, tissue weights at sacrifice, serum and liver lipid concentrations and serum, heart, brain and adipose tissue fatty acid compositions were studied. The food intake of the LF-fed animals was greater than that of animals fed on the high fat diets; there were no differences in food intake between animals fed the high fat diets. The total energy intake was lower for animals fed on the HCO diet than for those fed on the LF, OO, EPO or MO diets; there were no other differences in energy intake between the groups. Animals fed the different diets had almost identical rates of weight gain up to 5 weeks; after this period of rapid growth, the increase in weight was slower in all groups but especially in the LF-fed animals. The LF-fed rats had a lower total weight gain and smaller final weights than rats fed on the high fat diets. Animals fed on the MO diet had a greater weight gain than those fed on the OO or EPO diets and their final weights were greater. The MO diet resulted in greatly increased liver weight compared with each of the other diets. The HCO, OO and EPO diets also increased liver weight compared with the LF diet. The total lipid content of the livers from rats fed the high fat diets was greater than that of those from rats fed the LF diet; the livers from animals fed the MO diet contained more lipid than those from animals fed each of the other diets. MO feeding increased the free cholesterol, cholesterol ester and triacylglycerol contents of the liver.(ABSTRACT TRUNCATED AT 400 WORDS)

Increased ketone utilization by the kidney reduces renal lactate uptake but does not affect tubular sodium reabsorption

The purpose of the present study was to assess whether a moderate increase in ketonemia interferes with renal uptake of energy-providing substrates, and whether it may promote natriuresis similar to that occurring spontaneously during the early phase of starvation. To this end, the sodium salt of D(-)3-hydroxybutyrate (3OHB) was infused to 10 anesthetized dogs at a rate of 20 mumol/kg.min-1 over 135 minutes. To allow comparison, an equivalent amount of sodium was infused as sodium bicarbonate to 10 other dogs (to induce an alkalinization similar to that resulting from the utilization of the sodium salt of 3OHB), while 10 additional dogs received an equimolar infusion of NaCl to provide reference values. Before 3OHB or bicarbonate infusion, lactate represented the major fuel taken up by the kidney (28 +/- 3 mumol/100 g kidney.min-1 on average). While small but significant amounts of 3OHB were taken up by the kidney in control conditions (0.7 +/- 0.1 mumol/100 g.min-1; P < .05), there was no significant uptake of free fatty acids (FFA) or glucose. Upon 3OHB infusion, which increased plasma 3OHB levels to 1.7 mmol/L, the renal uptake of this substrate increased to 25 +/- 3 mumol/100 g.min-1, in proportion to renal 3OHB availability (r = .73, P < .001). Despite an increase in arterial lactate levels that occurred during 3OHB infusion, renal lactate uptake and the extraction ratio of this substrate were decreased (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of the apoA-II gene locus on HDL levels and fatty streak development in mice

Previous studies have shown that distal mouse chromosome 1 contains the apolipoprotein AII (apoAII) gene, encoding the second most abundant apolipoprotein in high density lipoproteins (HDLs), as well as a gene termed Ath-1 that controls aortic fatty streak development and HDL cholesterol levels in response to a high-fat, high-cholesterol diet. We report genetic studies confirming that the genes are distinct. Using molecular markers for mouse chromosome 1, we have further mapped the two genes, and our results indicate that they are separated by a minimum of 2 cM. We also report evidence that in mice on a low-fat chow diet, the apoAII gene locus influences HDL cholesterol levels. Thus, statistical analysis of two sets of recombinant inbred strains revealed concordant segregation patterns of HDL cholesterol levels and the apoAII gene locus. The effect of apoAII expression on HDL cholesterol levels was further tested by using a congenic strain that exhibits increased apoAII synthesis in comparison to the background strain. The results support the concept that increased synthesis of apoAII results in increased HDL cholesterol levels. Unexpectedly, increased expression of apoAII appeared to promote rather than retard aortic fatty streak development.

Reappraisal of the role of insulin on sodium handling by the kidney: f1fect of intrarenal insulin infusion in the dog

Since several studies suggest that increased insulin levels may induce antinatriuresis, the present work was undertaken to determine whether a physiological increase in insulin levels in blood perfusing the kidney may exert direct effect on kidney function, and more specifically on sodium reabsorption. To this end, insulin was infused directly into one renal artery of 10 anaesthetized dogs at the rate of 4 mU min-1 for a period of 90 min. The contralateral kidney was infused with saline alone, to provide reference values. Insulin level in the renal vein of the insulin-infused kidney went up from 1.4 +/- 0.9 before to 30.6 +/- 7.1 microU ml-1 after 90 min of insulin perfusion. There was no significant effect on renal plasma flow, glomerular filtration rate and renal uptake of substrates or oxygen between ipsi- and contralateral kidney. The fractional excretion of sodium was likewise unaffected, since it averaged at the end of insulin infusion 0.41 +/- 0.11% vs. 0.50 +/- 0.14% for the contralateral saline infused kidney. Even if one may assume that the baseline low insulin concentrations promote tubular sodium reabsorption, the results of the present study suggest that a moderate hyperinsulinaemia is without any additional effect on renal sodium handling.

Lipolytic enzyme and phospholipid level changes in intraoperative salvaged blood

Autotransfusion is becoming increasingly popular, mainly because it eliminates the risk of disease transmission. One of the techniques available is intra-operative blood salvage and retransfusion with or without washing of the collected blood. The blood collected during this process is subjected to a variety of chemical and physical insults which can alter the normal composition of the plasma by activating plasma and cellular homeostatic mechanisms. In this study, we measured the plasma levels of total phospholipids, lysolecithin and non-esterified fatty acids, and the lipolytic enzymes phospholipase A2 (PLA2) and lipase in the salvaged blood before and after washing. In the unwashed salvaged blood the mean levels of PLA2, non-esterified fatty acids and lysophospholipids increased by 144, 96 and 149%, respectively, while those of total phospholipids and lipase did not change to any extent. All these substances were reduced to well below the patients circulating plasma levels by washing the collected blood. The changes indicate that the lipid profile of salvaged blood is significantly altered and that potentially dangerous substances such as PLA2 and its metabolites, lysolecithin and non-esterified fatty acids, are present in increased amounts. Washing the blood is recommended prior to reinfusion.