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DGAT1 polymorphism in Bos indicus and Bos taurus cattle breeds.

As a result of multiple QTL-mapping projects in recent years, a quantitative trait locus for milk fat percentage and milk yield has been described on BTA14. Recent reports name the acyl-CoA : diacylglycerol acyltransferase (DGAT1) gene on BTA14 as a potential candidate gene, with a nonconservative substitution of lysine by alanine (K232A) producing a major effect on milk composition and yield. DGAT1K appears to be the ancestral allele and the K232A substitution probably occurred after the divergence of the Bos indicus and Bos taurus lineages. These findings prompted us to genotype 1748 DNA samples of 38 different Bos taurus and Bos indicus cattle breeds from 13 countries on five continents (Europe, Africa, Asia, North America and South America), to examine the occurrence of the DGAT1 polymorphism and characterize the K232A substitution in cattle breeds of different origins and selected for different purposes (e.g., beef, dairy and dual purpose). Calculating pairwise FST values for pooled subpopulations showed least divergence for Bos indicus breeds with high milk fat percentage. Fixation of DGAT1A was found in some Bos taurus breeds and fixation of DGAT1K in one Bos indicus breed. Breeds of no known organized breeding background from the Near East domestication centre of Bos taurus and taurine African N'Dama cattle were found to possess intermediate frequencies of DGAT1K. While beef breeds tended to harbour higher DGAT1A levels, dairy cattle showed everything from very low levels of DGAT1K to unexpectedly high frequencies of this allele.

Acyltransferases↗

Use of laminar cup liners for the preparation of fatty samples for pesticide analysis.

Residue analyses have been developed for hundreds of pesticides and their metabolites in foods. Normally, the fat is extracted with a non-polar solvent, followed by a re-extraction of the analytes into a polar solvent, removal of the remaining fat by several clean-up steps and finally determination by gas chromatography (GC). Over the last 3 years, experience has been gained in the use of laminar cup liners for GC injectors. The geometry of the laminar cup liner allows the injection of sample extracts with a residual fat content of tip to 5%. The cup prevents fatty compounds entering the capillary GC column. Using this approach, several residue methods can be simplified without losing precision or recovery. The preparation of the samples, such as cows milk, human milk, avocado and cosmetics can be reduced to one solvent extraction step with petroleum ether and one single cleanup step with an Extrelut column. No further clean up with Florisil or GPC is then necessary. The proposed method using a laminar cup and GC/ECD has been tested for the analysis of organochlorine and organophosphorous pesticides, PCBs, nitro-musk fragrances, together with pyrethroids and pyrethrins in the above matrices. Polycyclic musk substitutes were analysed by GC/MS.

Animals↗

Detection of polychlorinated biphenyls and dioxins in Belgian cattle and estimation of the maximal potential exposure in humans through diets of bovine origin.

The methodology used to detect a polychlorinated biphenyl (PCB)/dioxin contamination in a Belgian cattle population that was not exposed to the PCB/dioxin incident in 1999 is presented. This population is directly or indirectly destined for human consumption. The methodology consisted in the systematic sampling of all calf-fattening stations and groups of cattle destined for export, and in the random sampling of slaughter cattle. This approach is compared to the method described in directive 96/23/CE from the European Council. When PCB concentrations exceeded the tolerance level of 0.2 micro g/g body fat (seven congeners with numbers 28, 52, 101, 118, 138, 153, and 180), dioxins (seventeen 2,3,7,8-substituted congeners of PCDD and PCDF) were also determined. The prevalence of Belgian slaughter cattle with PCB concentrations above this cutoff was 0.3% (95% confidence interval: 0.01-1.50%). Results indicate that the incidence of contamination was minimal, with environmental origin and common in all industrial countries. The maximal potential exposure of an adult human consumer to dioxins through diet of bovine origin is estimated in two worst-case scenarios. The first one corresponds to the consumption of contaminated food products by a small number of consumers during a long period (local consumption) and the second simulates the consumption of contaminated products by a large number of consumers during a short period (supermarket purchase). The theoretical maximum daily intake of dioxins in adults was respectively 374 and 123 pg TEQ/d. The estimated maximum increase of dioxin body burden corresponds to 7 pg TEQ/g fat in the local consumption scheme and 0.07 pg TEQ/g fat in the supermarket consumption scheme.

Adult↗

Chronic ethanol feeding suppresses beta-adrenergic receptor-stimulated lipolysis in adipocytes isolated from epididymal fat.

Chronic ethanol consumption disrupts G protein-dependent signaling pathways in rat adipocytes. Because lipolysis in adipocytes is regulated by G protein-mediated cAMP signal transduction, we hypothesized that cAMP-regulated lipolysis may be vulnerable to long-term ethanol exposure. Male Wistar rats were fed a liquid diet containing ethanol as 35% of total calories or pair-fed a control diet that isocalorically substituted maltose dextrins for ethanol for 4 wk. Lipolysis was measured by glycerol release over 1 h with or without agonists in adipocytes isolated from epididymal fat. Chronic ethanol feeding decreased beta-adrenergic receptor-stimulated lipolysis, but had no effect on basal lipolysis. In response to beta-adrenergic activation, the early peak of cAMP accumulation was suppressed after ethanol feeding, although the basal cAMP concentration in adipocytes did not differ between pair- and ethanol-fed rats. The suppression in cAMP accumulation caused by ethanol feeding was associated with increased activity of phosphodiesterase 4. Chronic ethanol feeding also decreased beta-adrenergic receptor-stimulated protein kinase A activation and phosphorylation of its downstream proteins, perilipin A and hormone-sensitive lipase, the primary lipase-mediating lipolysis. In conclusion, these data suggest that chronic ethanol feeding increased phosphodiesterase 4 activity in adipocytes, resulting in decreased accumulation of cAMP in response to beta-adrenergic activation and a suppression of beta-adrenergic stimulation of lipolysis.

3',5'-Cyclic-AMP Phosphodiesterases↗

Effects of dietary protein on body weight, mucosal growth, and calcium absorption in the rat.

Previous studies of dietary protein intake and calcium balance demonstrate decreased fecal calcium excretion with high-protein diets. To determine whether a duodenal or ileal calcium transport response could account for these findings, we examined calcium transport by these two segments directly by in situ perfusion. Weight-matched growing rats were pair-fed isocaloric diets for 6-8 days containing 89% protein (casein), 39% and 0% protein. Sucrose was substituted for the decreased casein in the 39% and 0% protein diets. Each diet also contained 5% fat, a mineral mix, and vitamins. Calcium content of all diets was 0.5%. Body weight was maintained by the 39% protein group; weight loss was 5% for the 89% protein group and 18% for the 0% protein group. Small-intestinal weight as a percentage of body weight was the same for the three groups. For both the duodenum and the ileum, mucosal dry weight per centimeter was greater in the 39% protein group than either the 89% protein or 0% protein group. Calcium absorption per gram dry weight of mucosa (absorptive specific activity) was the same for all diet groups, but because of the greater mucosal weight per unit length in the 39% protein group, absorption per centimeter was increased in this group. In conclusion, although we found no direct relation between dietary protein and mucosal absorptive specific activity for calcium, calcium absorption was determined by the amount of mucosa which was dependent on protein intake and reflected the nutritional status of the body.

Animals↗

Analysis of mono-, di- and triglycerides in pharmaceutical excipients by capillary supercritical fluid chromatography.

Mono-, di- and triglycerides are important components of oils, fats and other natural products. Since in general fatty acids are mixtures and glycerol can be differently substituted, finger-prints of the composition are suitable for better characterization. Since capillary supercritical fluid chromatography (SFC) employing carbon dioxide as mobile phase is compatible with flame ionization detection, it is possible to analyse many solutes at trace levels. Supercritical carbon dioxide offers higher solute diffusivity compared with the inert carrier gas conventionally used in gas chromatography and has a lower viscosity than the liquid solvents used in HPLC. Thus, glycerides of fatty acids can be separated and eluted at a lower temperature and with shorter analysis time in SFC. In this study the analysis of mono-, di- and triglyceride mixtures in several pharmaceutical excipients is reported using capillary SFC. Quantitative analysis is possible on the basis of a response factor established for each analyte. The accuracy of the method and its advantages are demonstrated.

Caprylates↗

Placental, fetal, and neonatal carbohydrate metabolism.

In summary, glucose metabolism in the placenta and fetus is characterized by a fairly exact balance between exogenous glucose supply from the mother and placental and fetal glucose utilization (directly and as lactate produced from glucose). The rate of glucose utilization and its rate of oxidation are largely determined by the maternal glucose concentration and are mediated in part by insulin. Thus, glucose and insulin act together to substitute glucose oxidation for the oxidation of other energy substrates and to direct glucose carbon into glycogen, fat, and protein accretion. After birth, endogenous glucose production and dietary glucose intake (as glucose or as galactose) must account for the maintenance of glucose supply. In many cases, however, the balance among glucose intake, glucose production, and glucose utilization is inexact in the transition from intrauterine to extrauterine life, leading to both hypoglycemia and hyperglycemia. Basic measurements of the glucose production rate and the glucose utilization rate can be made now in the fetus as well as in the neonate, but the factors producing perturbations in glucose supply and utilization and in regulating the responses to these perturbations remain to be measured.

Animals↗

The pathophysiology of faecal spotting in obese subjects during treatment with orlistat.

BACKGROUND: The intermittent loss of oil or liquid faeces ('spotting') is an adverse effect that occurs in obese patients during treatment with the lipase inhibitor orlistat; the pathophysiology is unknown. AIM: To investigate the effects of orlistat on anorectal sensorimotor function and continence. METHODS: Obese subjects susceptible to spotting were identified by an unblind trial of orlistat. Obese spotters (n = 15) and non-spotters (n = 16) completed a randomized, double-blind, cross-over trial of orlistat and placebo. Anorectal function was assessed by rectal barostat and anal manometry, together with a novel stool substitute retention test, a quantitative measurement of faecal continence. RESULTS: Orlistat increased stool volume and raised faecal fat and water. Treatment had no effect on anorectal motor function, but rectal sensation was reduced; on retention testing, the volume retained was increased. Subjects susceptible to spotting had lower rectal compliance, heightened rectal sensitivity and weaker resting sphincter pressure than non-spotters. On retention testing, gross continence was maintained; however, spotters lost small volumes of rectal contents during rectal filling. CONCLUSION: Treatment with orlistat has no direct adverse effects on anorectal function or continence. Spotting occurs during treatment with orlistat when patients with sub-clinical anorectal dysfunction are exposed to increased stool volume and altered stool composition.

Adult↗

Physicochemical properties of some organophosphates in relation to their chronic toxicity.

Organophosphates in increasing amounts and wider varieties of molecular structure are being used to replace the organochlorine pesticides. It has been assumed that the organophosphates as a class would have a minimal chronic toxicity due to rapid hydrolysis and an unfavorable partitioning as regards to lipids. The physicochemical properties of a number of representative organophosphates were determined, including the octanol/water partition coeffecient, hydrolysis, and binding to proteins. Those having a halogenated aryl substitution were found to have partition coefficients not largely different from the organochlorines, suggesting the possibility of fat deposition. Certain of these compounds are sufficiently stable toward hydrolysis to allow bioaccumulation to occur. These preliminary findings appear to indicate a correlation between readily determined physical properties and the potential for chronic effects in this class of compounds.

Animals↗

Glucocorticoid-dependency of increased adiposity in a model of hypothalamic obesity.

UNLABELLED: It is known that rats treated, at neonatal age, with monosodium L-glutamate (MSG) develop neuroendocrine and metabolic abnormalities, resulting in a phenotype of hypothalamic obesity, characterized by increased adiposity, corticosteronemia and leptinemia. OBJECTIVE: We explored whether adrenal manipulations could result in the reversion of this phenotype of hypothalamic obesity. EXPERIMENTAL DESIGNS: Newborn male rats, treated with MSG or vehicle (CTR), were submitted to sham operation, bilateral adrenalectomy (ADX) or bilateral adrenal enucleation (AE) on day 120 of age. Animals were examined 21 days after ADX, combined or not with corticosterone (B) substitution (ADX+B), and on days 21 and 35 after AE. Food intake, body weight and body fat mass were monitored; additionally circulating levels of insulin, leptin, ACTH and B were measured. RESULTS: Our data indicate that: a) normalization of basal B circulating levels in, 21 day-ADX and -AE, MSG rats fully reversed hyperinsulinemia, hyperleptinemia and significantly decreased body fat mass; and b) recovery of hypercorticosteronemia in, 35 day-AE, MSG rats fully restored this phenotype of hypothalamic obesity. CONCLUSION: Our study strongly supports that high glucocorticoid production is the main factor responsible for the development of enhanced adiposity in MSG rats and, importantly, that this abnormality could be reversed by an appropriate therapy.

Adipose Tissue↗

Replacement of margarine on bread by rapeseed and olive oils: effects on plasma fatty acid composition and serum cholesterol.

The effects of zero erucic acid rapeseed oil and olive oil on plasma fatty acid composition and serum cholesterol were studied in margarine users (n = 46). The replacement of margarine on bread by these oils accounted, on average, for 16% of the total fat and 7% of the total energy intake. Fatty acid analysis of total plasma indicated a dose-dependent rise in alpha-linolenic (alpha-LLA) and oleic acid (OA) levels during rapeseed and olive oil substitutions, respectively. Rapeseed oil substitution increased the proportion of eicosapentaenoic acid (0.4%- units, on average) in plasma phospholipids. A slight decrease in low-density lipoprotein cholesterol (LDL-C) and an increase in high-density lipoprotein cholesterol (HDL-C, 4.5%, p < 0.01) led to a significantly higher HDL-C/total cholesterol (TC) ratio (1.9%-units). The results suggest a marked competitive effect for alpha-LLA, not only among plasma phospholipid fatty acids, but also in the relationships with serum lipids, since the changes in alpha-LLA, rather than in OA, were associated with those in LDL-C and the HDL-C/TC ratio. No competitive action of polyunsaturated acids comparable to rapeseed oil was found during olive oil substitution. In contrast to the rapeseed oil diet, the reduced proportion of linoleic acid (LA) in plasma phospholipids was not restored; this may be unfavorable if the habitual intake of LA is low. However, the effects on LDL-C levels were beneficial: the concentration decreased by 5.9% (p < 0.01), correlating inversely with the increase in OA. In addition, the concentration of HDL-C remained unchanged during olive oil substitution.

Adult↗

The nutritional value of high-oil corn for broiler chicks.

A variety of corn (Natan) with high fat and protein contents (6.7 and 9.8%, respectively) was developed at Newe Ya'ar, Israel. The nutritive value of this corn for broiler chicks from 7 to 28 d of age was evaluated in two experiments. In the first experiment, Natan and a local conventional corn variety (LCC-2.9% fat and 7.2% protein) were incorporated in a relatively low-protein diet designated for the determination of AMEn by the substitution method. The AMEn content of Natan was found to be 3,658 kcal/kg, whereas that of LCC was 3,437 kcal/kg. There were no differences in feed intake or weight gain between chicks fed the two corn varieties, but feed efficiency of those fed the diet containing Natan was improved (P < .05). In the second experiment, the effects on the performance of chicks of diets adequate in protein and containing either imported conventional corn (ICC), or Natan, or ICC-enriched with corn oil and soybean meal (to equalize its fat and protein content to that of the diet containing Natan), were compared. There were no differences in feed intake or weight gain among chicks fed the three diets and in feed efficiency among chicks fed the diet containing Natan and those fed the other two diets, whereas, the enrichment of the ICC-containing diet significantly improved feed efficiency. It was concluded, therefore, that in spite of the high nutritional value of the high-oil corn, its effect on improving the performance of chicks, when replacing a conventional corn in a well-balanced diet, was not pronounced.

Animal Feed↗

Fat emulsion for intravenous administration: clinical experience with intralipid 10%.

A 10% soybean oil emulsion (Intralipid 10%), used extensively in Europe for intravenous alimentation, has now been clinically evaluated in the United States. Controlled studies have shown that the soybean oil emulsion can be substituted for glucose to supply one-third to two-thirds of the total calories, and can be administered peripherally without significant vein irritation. Essential fatty acid deficiencies, frequently encountered in patients dependent on parenteral alimentation with fat-free solutions, are prevented and corrected by use of this preparation. Data on long-term tolerance to Intralipid 10% infusions are presented for 292 patients treated for more than 6,000 patient days. The soybean oil emulsion was usually well tolerated. Side effects were reported in two of 133 adults and 12 of 159 pediatric patients.

Adult↗

Evidence that cysteine, not selenocysteine, is in the catalytic site of type II iodothyronine deiodinase.

Recent cloning of the cDNA for Type I iodothyronine deiodinase revealed that the mRNA contains a UGA codon encoding the amino acid selenocysteine. Mutagenesis of the selenocysteine codon to a cysteine codon produced a protein with lower deiodinase activity. The presence or absence of selenocysteine in Type II deiodinase, which differs from the Type I enzyme in a number of parameters, has not been determined. Gold inhibits the activity of both the Type I deiodinase and the only other known eukaryotic selenocysteine-enzyme, glutathione peroxidase. Substitution of cysteine for selenocysteine in Type I deiodinase reduced its sensitivity to inhibition by gold 500-fold. We found that gold thioglucose was a competitive inhibitor with respect to the iodothyronine substrate of both deiodinases. However, the Type II enzyme from brown fat and pituitary was 100 to 1000-fold less sensitive to gold than was Type I activity in liver and pituitary, similar to the results with the cysteine-substituted Type I enzyme. This suggests that Type II deiodinase contains cysteine instead of selenocysteine in the active site.

Adipose Tissue, Brown↗

The regulation of adipose tissue distribution in humans.

The regulation of adipose tissue distribution is an important problem in view of the close epidemiological and metabolic associations between centralized fat accumulation and disease. With visceral fat accumulation multiple endocrine perturbations are found, including elevated cortisol and androgens in women, as well as low growth hormone (GH) and, in men, testosterone (T) secretion. These abnormalities probably derive from a hypersensitive hypothalamo-pituitary-adrenal axis, with hyperinsulinemia related to a marked insulin resistance as a consequence. These hormonal changes exert profound effects on adipose tissue metabolism and distribution. At the adipocyte level cortisol and insulin promote lipid accumulation by expressing lipoprotein lipase activity, while T, GH and probably estrogens exert opposite effects. The consequences will most likely be more expressed in visceral than subcutaneous adipose tissues because of a higher cellularity, innervation and blood flow. Furthermore, the density of cortisol and androgen receptors seems to be higher in this than other adipose tissue regions. The endocrine perturbations found in visceral obesity with an abundance of the lipid accumulating hormones cortisol and insulin, and a relatively low secretion of the lipid mobilizing sex steroid hormones and GH would therefore be expected to be followed by visceral fat accumulation. The potential significance of local synthesis of steroid hormones in adipose tissue requires more attention. Although studies in vitro are informative when elucidating detailed mechanisms of hormonal interactions, they might not give a true picture of the regional integrated regulation of adipose tissue lipid storage and mobilization. Such information can be obtained by regional measurements of lipid mobilization by free fatty acid turnover or by microdialysis techniques, both showing lower rates of mobilization in leg than in upper body adipose tissues. More detailed information can be obtained by physiological oral administration of triglycerides, labelled with a small amount of oleic acid, followed by measurements of the regional uptake and turn-over of adipose tissue triglycerides. Such studies show lipid uptake in the order omental = retroperitoneal > subcutaneous abdominal > subcutaneous femoral adipose tissues in men, with a similar rank order for half-life of the triglyceride, indicating also a turn-over of triglycerides in that order. T amplifies these differences in men. In premenopausal women subcutaneous abdominal has a higher turnover than femoral adipose tissue. Results of studies in vitro indicate that this difference is diminished at the menopause, and restored by estrogen substitution, suggesting that the functional effects of estrogens in women are similar to those of T in men. The mechanisms are, however, probably indirect because of the apparent absence of specific estrogen and progesterone receptors in human adipose tissue. This interpretation from the studies referred to above fits well with physiological, and clinical conditions with increased visceral fat mass, where the balance between the lipid accumulating hormone couple (cortisol and insulin) and the hormones which prevent lipid accumulation and instead activate lipid mobilization pathways (sex steroid hormones and GH) is shifted to the advantage of the former. Such conditions include Cushing's syndrome, the polycystic ovary syndrome, menopause, aging, GH-deficiency, depression, smoking and excess alcohol intake. With appropriate interventions against hypercortisolemia and substitution of deficient sex steroids and GH, visceral fat mass is decreasing. Based on this evidence from physiological, clinical, interventional observations and detailed studies of mechanisms at cellular and molecular levels it is suggested that the combined endocrine abnormalities in the syndrome of visceral obesity direct storage fat to visceral adipose depots. Therefore, measurements of visceral fat accumulat

Adipose Tissue↗

[Changes in body composition in adult patients with hypopituitarism after substitutive treatment with growth hormone].

BACKGROUND: Adult growth hormone (GH) deficiency is associated with changes in body composition, with lower total body water (TBW) and fat free mass (FFM) and higher fat mass (FM). These changes can be modified after sustitutive treatment with GH. PATIENTS AND METHODS: We studied 20 patients, 14 males and 6 females with hypopituitarism and GH deficiency, the mean age was 40.3 years, as well as 20 comparable controls. The diagnosis of GH deficiency was based on the lack of GH response after an hypoglycemic test. We determined body composition by bioelectrical impedance. An initial 6 month double-blind placebo controlled phase was followed by an open treatment phase ending when the patients had received GH for 18 or 24 months. The initial dose was 0.125 U/kg/week during the first month and after 0.25 U/kg/week. RESULTS: The patients showed lower TWB and FFM and higher BF in relation to controls and after 3 months of GH treatment an increase of the TBW, FFM and a decrease in BF and waist/hip ratio was observed with a steady state in the changes of body composition after 3 months that continued 6 months after the GH treatment withdraw. Two patients presented maleolar oedema, 4 arterial hypertension that was settled with GH dose reduction and in the fourth patient the treatment had to be withdraw. Three patients presented carpal tunnel syndrome. In 4 patients the treatment was withdrawn. CONCLUSIONS: In patients with adult GH deficiency, we can observe differences in the body composition that can be significantly modified by GH treatment.

Adult↗