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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Substantial data are available to indicate that the diet influences serum levels of cholesterol and lipoproteins. These data are derived from studies in laboratory animals, from epidemiologic studies, and from human investigations. Most research has focused on effects of diet on serum total cholesterol concentrations. In recent years, however, attention has shifted to individual lipoproteins, i.e., low density lipoproteins (LDL), high density lipoproteins (HDL), and very low density lipoproteins (VLDL). Three nutritional factors have been identified that raise serum LDL levels; these are saturated fatty acids, cholesterol itself, and excess caloric intake leading to obesity. The major cholesterol-raising saturated fatty acid in the diet is palmitic acid. Several nutrients can be substituted for saturated fatty acids to produce a reduction in LDL-cholesterol levels. These are polyunsaturated fatty acids, monounsaturated fatty acids, carbohydrates, and even one saturated fatty acid, stearic acid. The latter appears to be converted rapidly into a monounsaturated fatty acid in the body. Any of these nutrients can be used for replacement of cholesterol-raising saturated fatty acids in the diet. However, their relative effects on other metabolic processes remain to be determined fully. At present it appears that carbohydrates and monounsaturated fatty acids represent the preferred replacements for saturated fatty acids, although modest increases in polyunsaturated fatty acids and stearic acid, at the expense of cholesterol-raising saturates, probably are safe and may provide for greater variety in the diet.
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PMID:Dietary influences on serum lipids and lipoproteins. 220 99

The role of the sympathetic nervous system in free fatty acid (FFA) mobilization was assessed in this study. FFA turnover rate using 1-14C-palmitic acid and metabolic rate by using indirect calorimetry were measured in ten white and 12 Pima Indian males after an overnight fast and during propranolol infusion (120 micrograms/kg fat-free mass [FFM] bolus and 1.2 micrograms/kg FFM/min). Baseline FFA turnovers were similar in both racial groups and decreased similarly following propranolol infusion (-16% +/- 4%; P less than .001, n = 22). This decrease was greater in more obese subjects (decrease in FFA turnover v % body fat, r = -.59, P less than .01, n = 22). Propranolol also induced an increase in lipid oxidation, which was more marked in the subjects with a high ratio of abdomen to thigh circumference (A/T ratio) (r = .63, P less than .01, n = 22). On average the resting metabolic rate (RMR) was unchanged during propranolol infusion, but individuals with lower A/T ratio had greater decreases in RMR than subjects with higher A/T ratio (r = .48, P less than .05). Assuming that the change in FFA turnover following beta-blockade is proportional to the role that the catecholamines (and therefore the sympathetic nervous system) play in mobilization of FFA, the greater fall in FFA turnover after propranolol infusion in more obese subjects suggests that they have a higher basal sympathetic activity. Furthermore, the lack of decrease in metabolic rate in response to beta-blockade in persons with a high A/T ratio could be the reflection of an even greater SNS activity in individuals with central obesity.
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PMID:The effect of propranolol on free fatty acid mobilization and resting metabolic rate. 272 82

Obese strain (OS) chickens hatched in the NIU vivarium were observed, primarily with respect to serum lipid and lipoprotein parameters, over a period of 36 weeks. The hypothyroid birds began to show differences in total serum lipids as compared to non-OS controls as early as 4 weeks post-hatching. All lipaemic chickens displayed lack (or deficiency) of thyroid tissue. Although all the thyroid deficient chickens showed increases in serum lipids, they were individually highly variable with respect to both quantity of serum lipid and time of onset of severe lipaemia. Six of twenty four OS birds became severely hyperlipaemic. One of these displayed a level of serum lipid amounting to 323 mg/ml. The increased serum lipid consisted primarily of triglyceride and phospholipid and was not accompanied by corresponding increases in apoproteins B or A-I. However, because of its high content of palmitic acid, oleic acid and phospholipid, the bulk of the serum lipid in OS birds appeared to be derived from the liver rather than directly from the diet. It is concluded that sufficient phospholipid was present in the plasma to form micelles, thus reducing requirements for association of solubilizing apoproteins. Livers were considerably enlarged in hyperlipaemic birds, possibly to compensate for decreases in lipid synthesizing enzymes per unit mass of tissue. However, results of gamma-irradiation of OS chickens (showing exacerbation of hyperlipaemia) indicated that hyperlipaemia in OS birds may be largely due to widespread failure of the body's cells to utilize foodstuffs and of adipose tissue to store excessive amounts of fatty acids as triglyceride.
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PMID:Serum lipids and lipoproteins in hypothyroidism. 379 54

Compared to its lean litter mate (Fa/--) the Zucker rat (fa/fa) develops obesity without hyperphagia in the first week of lite. It is characterized by adipocyte hypertrophy and higher lipid content in adipose tissue. In vitro utilization as well as in vitro oxidation by diaphragm of palmitic acid was decreased in 1 week old Zucker rat.
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PMID:[Lipid metabolism in the newborn genetically obese (fa/fa) rat]. 644 38

The influence of a diet including 18 per cent by weight of long-chain (LCT) or medium-chain (MCT) triacylglycerols on adipose tissue development, and on in-vitro adipose tissue triacylglycerol (TG) synthesis from glucose and palmitic acid, was studied using genetically obese, fa/fa, and control, Fa/-, Zucker rats. The adipose tissue mass was greater with the LCT diet than with either the MCT or control diets, but there was no significant difference between the MCT and control diets. TG synthesis from labelled substrates was not modified by the MCT diet when compared with the control, but was decreased by the LCT diet. The results suggested that the use of MCT in treating human obesity would necessitate levels too high to be therapeutically practical.
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PMID:Effects of medium- and long-chain triacylglycerols on adipose tissue metabolism in the obese Zucker rat. 686 60

The aim of the investigation was to see whether a defect in energy expenditure could be found in the Zucker rat at the onset of obesity. Obese (fa/fa) and lean (Fa/fa) 7-day-old pups were studied at three ambient temperatures. At 33 degrees C fa/fa pups showed a reduction in oxygen consumption, respiratory CO2 production, in vivo oxidation of injected [1-14C]palmitic acid, as well as in core temperature. When the pups were kept at 28 degrees C, the difference between genotypes was considerably accentuated, thus indicating a subnormal thermogenic response of the fa/fa pups to a mildly cold environment. At 20 degrees C, however, the metabolic rates dropped to the same low level, and the core temperature equilibrated with ambient temperature in both genotypes. The results demonstrate that the 1-wk-old fa/fa pup has a defect in thermoregulatory thermogenesis. The magnitude of the deficit in energy expenditure was more than adequate to account for the 50% greater fat content of 7-day-old fa/fa pups.
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PMID:Evidence of a defect in energy expenditure in 7-day-old Zucker rat (fa/fa). 688 26

Mice fed a high-fat diet develop hyperglycemia and obesity. Using non-insulin-dependent diabetes mellitus (NIDDM) model mice, we investigated the effects of seven different dietary oils on glucose metabolism: palm oil, which contains mainly 45% palmitic acid (16:0) and 40% oleic acid (18:1); lard oil, 24% palmitic and 44% oleic acid; rapeseed oil, 59% oleic and 20% linoleic acid (18:2); soybean oil, 24% oleic and 54% linoleic acid; safflower oil, 76% linoleic acid; perilla oil, 58% alpha-linolenic acid; and tuna fish oil, 7% eicosapentaenoic acid and 23% docosahexaenoic acid. C57BL/6J mice received each as a high-fat diet (60% of total calories) for 19 weeks (n = 6 to 11 per group). After 19 weeks of feeding, body weight induced by the diets was in the following order: soybean > palm > or = lard > or = rapeseed > or = safflower > or = perilla > fish oil. Glucose levels 30 minutes after a glucose load were highest for safflower oil (approximately 21.5 mmol/L), modest for rapeseed oil, soybean oil, and lard (approximately 17.6 mmol/L), mild for perilla, fish, and palm oil (approximately 13.8 mmol/L), and minimal for high-carbohydrate meals (approximately 10.4 mmol/L). Only palm oil-fed mice showed fasting hyperinsulinemia (P < .001). By stepwise multiple regression analysis, body weight (or white adipose tissue [WAT] weight) and intake of linoleic acid (or n-3/n-6 ratio) were chosen as independent variables to affect glucose tolerance. By univariate analysis, the linoleic acid intake had a positive correlation with blood glucose level (r = .83, P = .02) but not with obesity (r = .46, P = .30). These data indicate that (1) fasting blood insulin levels vary among fat subtypes, and a higher fasting blood insulin level in palm oil-fed mice may explain their better glycemic control irrespective of their marked obesity; (2) a favorable glucose response induced by fish oil feeding may be mediated by a decrease of body weight; and (3) obesity and a higher intake of linoleic acid are independent risk factors for dysregulation of glucose tolerance.
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PMID:High-fat diet-induced hyperglycemia and obesity in mice: differential effects of dietary oils. 896 89

A follow-up study was conducted to identify the heart disease risk-factor status and dietary changes of surviving elderly subjects in Crete who took part in the Seven Countries Study in 1960. In 1991, data were obtained from 245 of the 686 original male participants (169 of the original 40-49-y age group and 76 men 50-59 y age group). In 1991, the men were 70-79 and 80-89 y old. There was a significant (11.5%) increase in serum total cholesterol concentrations between 1960 and 1991. Body mass index and systolic and diastolic blood pressures also increased significantly, and all age groups were characterized by central obesity. A representative subsample of 21 men took part in a 3-d weighed food record study. Dietary data indicated increases in the intake of saturated fat and decreases in monounsaturated fat over the 30-y period. Comparison with a 1962 representative Cretan sample indicated a significantly increased concentration of adipose palmitic acid (16:0) in our surviving sample. The observed changes occurred during a period when many developed countries were observing a decline in most heart disease risk factors.
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PMID:Heart disease risk-factor status and dietary changes in the Cretan population over the past 30 y: the Seven Countries Study. 917 87

To understand the role of free fatty acid (FFA) incorporation in the accumulation of lipids in the adipocyte and ultimately in the development of obesity, 13C nuclear magnetic resonance was used to study lipid metabolism in differentiating preadipocytes. The incorporation of 13C=O-labeled FFA into cellular lipids in primary cultured rat preadipocytes and 3T3L1 preadipocytes at different stages of differentiation was monitored by the 13C carbonyl chemical shift. Significant incorporation of palmitic acid into phosphatidylcholine in both the alpha and beta acyl chain positions was found in cells at early stages of differentiation. At later differentiation stages or after extended incubation periods, most of the 13C=O signals were found in the triacylglycerol (TG) molecules. Unsaturated 13C=O-labeled acyl chains were detected in the TG molecules when cells were incubated with saturated 13C=O-labeled FFA, indicating that intracellular dehydrogenation had occurred in the 13C=O-labeled palmitoyl chain. By using 13C-labeled methyl myristate as an internal intensity reference, incorporation of 13C FFA into each acyl chain position of the major intracellular lipids was determined quantitatively.
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PMID:A 13C nuclear magnetic resonance study of free fatty acid incorporation in acylated lipids in differentiating preadipocytes. 962 91

Twenty-nine obese female Zucker rats (fa/fa) were fed with a laboratory chow supplemented or not with a selenium-rich yeast (Selenion), or Selenion + vitamin E, or vitamin E alone. Twelve lean female Zucker rats (Fa/Fa) of the same littermates fed with the same diet were used as control. After 32 wk of diet, obesity induced a large increase in plasma insulin and lipid levels. A significant decrease in the plasma vitamin E/triglycerides ratio (p<0.005) and an increase in plasma thiobarbituric reactive substances (TBARS) (p<0.005) were also observed. Plasma selenium and vitamin E increased in all supplemented rats. The plasma insulin level was decreased by selenion supplementation and the vitamin E/triglycerides ratio was completely corrected by double supplementation with Selenion + vitamin E. TBARS were also efficiently decreased in two obese groups receiving vitamin E. In plasma, adipose tissue and aorta, obesity induced an increase in palmitic acid (C16:0), a very large increase in monounsaturated fatty acids (palmitoleic acid C16:1, stearic acid C18:1) associated with a decrease in polyunsaturated n-6 fatty acids (linoleic acid C18:2 n-6, arachidonic C20:4 n-6). These alterations in fatty acid distribution were only partly modulated by Se and vitamin E supplements. However, in the aorta, antioxidant treatment in obese rats significantly reduced the increase in C16:0 and C16:1 (p<0.05 and p<0.01, respectively) and the decrease in arachidonic acid (p<0.05). These changes could be beneficial in the reduction of insulin resistance and help to protect the vascular endothelium.
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PMID:Effect of selenium and vitamin E supplementation on lipid abnormalities in plasma, aorta, and adipose tissue of Zucker rats. 989 95


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