The effect of fasting lipid levels on alimentary lipemia.
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Obesity is a major public health problem. The increasing number of obese individuals in the US adds urgency to the efforts to understand the mechanisms underlying pathological overeating. Imaging studies using positron emission tomography implicate the involvement of brain dopamine (DA) in normal and pathological food intake in humans. In normal body weight, fasting subjects, food presentation that could not be consumed was associated with increases in striatal extracellular DA, which provides evidence of an involvement of DA in non-hedonic motivational properties of food intake. In pathologically obese subjects, the authors showed reductions in striatal D2 receptor availability that were inversely associated with the weight of the subject. The involvement of the DA system in reward and reinforcement has led to the hypothesis that low brain DA activity in obese subjects predisposes them to excessive use of food. A better understanding of the role of the DA system in the motivation for food intake will help the development of better therapeutic interventions.
Summarized are the significance of fasting in Islam, the rules and regulations of fasting, types of fasting, nullification of fasting, and food practices and habits of Muslims during the fasting month of Ramadan. Some problems pertaining to fasting and their solutions are also considered, and applications of fasting to America have been pointed out. It is hoped that this paper may bring a new dimension to the sphere of cultural nutrition and encourage partial fasting as a means of curbing inflation and helping the poor, the needy, and hungry all over the world.
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In 10 dogs with Heidenhain pouches (HP) a gastrojejunostomy (GEA) was constructed and later converted into a Roux en-Y anastomosis in order to abolish or reduce transstomal reflux. Next, duodenal inhibition was abolished by duodenal transection, and finally the duodenal bulb was excised. Twenty-four hour HP acid output increased after GEA, some 70% of the increase being attributable to transstomal reflux, the rest to decreased duodenal inhibition. Abolished duodenal inhibition caused a new rise, not significantly different from that caused by the combined effect of reflux and decreased duodenal inhibition after GEA. Twenty-four hour fasting HP acid output and 5 hr food-stimulated HP acid output rose after GEA by the same amount as that caused by abolished duodenal inhibition. A significant correlation was found between integrated gastrin and total HP acid output after food stimulation. Both fasting and food-stimulated gastrin concentration rose after GEA, the latter caused by reflux alone. Elimination of duodenal inhibition caused an unexpected rise in both fasting and food-stimulated gastrin concentration.
Leptin is a key factor in the regulation of food intake and is an important factor in the pathophysiology of obesity. However, more than a decade after the discovery of leptin in mouse, information regarding leptin in any nonmammalian species is still scant. We report the identification of duplicate leptin genes in common carp (Cyprinus carpio). The unique gene structure, the conservation of both cysteines that form leptin's single disulfide bridge, and stable clustering in phylogenetic analyses substantiate the unambiguous orthology of mammalian and carp leptins, despite low amino acid identity. The liver is a major yet not the only site of leptin expression. However, neither 6 d nor 6 wk of fasting nor subsequent refeeding affected hepatic leptin expression, although the carp predictably shifted from carbohydrate to lipid metabolism. Animals that were fed to satiation grew twice as fast as controls; however, they did not show increased leptin expression at the termination of the study. Hepatic leptin expression did, however, display an acute and transient postprandial increase that follows the postprandial plasma glucose peak. In summary, leptin mRNA expression in carp changes acutely after food intake, but involvement of leptin in the long-term regulation of food intake and energy metabolism was not evident from fasting for days or weeks or long-term feeding to satiation. These are the first data on the regulation of leptin expression in any nonmammalian species.
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1. The effects of food and antacid on the pharmacokinetics of tenidap were investigated in this randomised, 3-way cross-over study. 2. Twenty-one healthy young men, mean age 27.4 years, received single oral doses of tenidap sodium 120 mg at weekly intervals after either an overnight fast, with food or with 20 ml of the antacid Maalox (aluminum hydroxide 1.8 g and magnesium hydroxide 1.2 g). Plasma samples collected immediately before and up to 96 h after each tenidap dose were assayed for tenidap using a validated h.p.l.c. method. The assay data were used to determine the pharmacokinetic parameters of tenidap in each group. 3. Co-administration of tenidap with food produced a statistically significant delay in the rate of absorption (tmax, 4.4 h) (P < 0.001). There was no statistically significant change in Cmax. However, co-administration with the antacid significantly decreased both the mean rate and extent of absorption of tenidap compared with the fasting state: AUC, 420.93 micrograms ml-1 h (antacid), 476.31 micrograms ml-1 h (fasting) (P = 0.026); Cmax 14.3 micrograms ml-1 (antacid), 18.0 micrograms ml-1 (fasting) (P = 0.001); tmax 4.5 h (antacid), 2.9 h (fasting) (P < 0.001). Neither food nor the antacid had any effect on the elimination of tenidap. These changes in tmax are unlikely to be of any clinical significance owing to the long half-life of tenidap. 4. Treatment was well tolerated. Only two adverse events were reported that were considered by the investigator to be related to tenidap. There were no reports of laboratory or cardiovascular abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)
OBJECTIVE: To study the role of ghrelin as a hunger signal during energy restriction and to test the hypothesis that changes in fasting leptin concentrations during energy restriction are associated with changes in fasting ghrelin concentrations. RESEARCH METHODS AND PROCEDURES: Thirty-five healthy, lean men (23 +/- 3 years of age; BMI: 22.3 +/- 1.6 kg/m(2)) participated in a controlled intervention study. Fasting ghrelin and leptin concentrations were measured before and after 2 days of 62% energy restriction and after a 2-day period of ad libitum food intake. Energy intake during the latter period was assessed. RESULTS: On average, ghrelin concentrations did not change (0.05 mug/liter; 95% confidence interval, -0.03; 0.12) during energy restriction. Changes in ghrelin concentration during energy restriction were not associated with energy intake during the ad libitum period (r = 0.07; not significant). Ad libitum energy intake was, however, associated with the change in ghrelin concentrations during the same period (r = -0.34; p = 0.05). Ghrelin and leptin concentrations were not associated. In addition, the ratio of percentage changes in ghrelin and leptin during energy restriction was not correlated with ad libitum food intake after energy restriction (r = -0.26; p = 0.14). DISCUSSION: Fasting ghrelin concentrations did not rise after a 2-day energy restriction regimen. Moreover, changes in ghrelin concentrations during energy restriction were not associated with subsequent ad libitum food intake, suggesting that fasting ghrelin does not act as a hunger signal to the brain. The data did not support our hypothesis that leptin suppresses ghrelin levels.
Two studies were performed to examine the influence of fasting and food intake on the absorption and retention of nickel added to drinking water and to determine if nickel sensitization played any role in this regard. First, eight nonallergic male volunteers fasted overnight before being given nickel in drinking water (12 micrograms Ni/kg) and, at different time intervals, standardized 1400-kJ portions of scrambled eggs. When nickel was ingested in water 30 min or 1 h prior to the meal, peak nickel concentrations in serum occurred 1 h after the water intake, and the peak was 13-fold higher than the one seen 1 h after simultaneous intake of nickel-containing water and scrambled eggs. In the latter case, a smaller, delayed peak occurred 3 h after the meal. Median urinary nickel excretion half-times varied between 19.9 and 26.7 h. Within 3 days, the amount of nickel excreted corresponded to 2.5% of the nickel ingested when it was mixed into the scrambled eggs. Increasing amounts were excreted as the interval between the water and the meal increased, with 25.8% of the administered dose being excreted when the eggs were served 4 h prior to the nickel-containing drinking water. In the second experiment, a stable nickel isotope, 61Ni, was given in drinking water to 20 nickel-sensitized women and 20 age-matched controls, both groups having vesicular hand eczema of the pompholyx type. Nine of 20 nickel allergic eczema patients experienced aggravation of hand eczema after nickel administration, and three also developed a maculopapular exanthema. No exacerbation was seen in the control group. The course of nickel absorption and excretion in the allergic groups did not differ and was similar to the pattern seen in the first study, although the absorption in the women was less. A sex-related difference in gastric emptying rates may play a role. Thus, food intake and gastric emptying are of substantial significance for the bioavailability of nickel from aqueous solutions.
Organisms through phenotypic plasticity can cope with multiple changed environmental conditions. Theory predicts that animals in streams and rivers should be able to balance demands of the needs to obtain food efficiently and to adjust response to hydrodynamic variability. This study examined effects of variations in food availability and current velocity on the feeding structure and growth rate of Simulium noelleri blackfly larvae. The larvae developed larger labral fans and more rays under slow current and low food regimes than in fast current and high food conditions. In both fast and slow current regimes, growth rates were higher and development periods to the final-instar stage were shorter in high food treatments. The estimated flux rates of food particles through labral fans under high food treatments for both fast and slow current regimes were higher than those under low food treatments. Although both food and current velocity appeared to have selected for flexibility of feeding structure and growth rate, food availability was a more important factor for phenotypic and developmental plasticity than current velocity. The results indicate a strong link between environmental changes in food availability and current velocity, phenotypic plasticity, and growth rate of S. noelleri. This study suggests that plasticity of ecomorphs with macroevolutionary significance may play a role in the early evolutionary stages of blackfly larvae.
Moricizine, a unique Class I antiarrhythmic agent, was orally administered with and without a meal to 24 healthy male subjects to determine the effect of food on moricizine absorption and bioavailability. Relative to the fasting state, a standardized breakfast delayed the time to peak plasma moricizine concentration (1.2 vs. 0.9 hr; P less than .03) and lowered peak plasma moricizine concentration by 24% (0.55 vs. 0.72 microgram/mL; P less than .03). Bioavailability, as measured by area under the plasma moricizine concentration versus time curve, was not significantly altered by the meal.
Juvenile bullfrogs from natural populations doubled their glycogen stores during their predormancy period, while their blood glucose and lipid stores declined. Glycogen stores were replenished in natural populations as food consumption decreased. Some liver glycogen was stored during fasting if the bullfrogs were collected in the storage phase of their energy reserve cycle, but the amount of glycogen stored was increased by feeding.
Syrian hamsters do not increase their food intake following several metabolic challenges, including food deprivation and blockade of metabolic fuel utilization, in contrast to the response of other small rodents to these challenges. Perhaps hamsters respond to such challenges differently, for example by altering hoarding. In the present experiments, we have begun to question the role of food hoarding in the total energy balance of Siberian hamsters. Therefore, we developed a simulated burrow system, where food was available outside the burrow for consumption and/or hoarding during a 15-h period surrounding the 8-h dark portion of the photocycle. Food hoarding, but not food intake, increased dramatically after 32- and 56-h fasts and was greater following the longer fast. Food-restricted weight-reduced hamsters (80% of ad libitum-fed controls) were refed and given the opportunity to hoard. Initially, when body weights were low, food hoarding was maximal and then decreased gradually to control levels as body weights reached those of the ad libitum-fed controls. Food intake was not affected. Neither hoarding nor food intake was affected by treatment with long-acting protamine zinc insulin, given to enhance the storage of metabolic fuels, at any dose tested. Finally, neither food intake nor hoarding was affected by treatment with the glucose utilization blocker 2-deoxy-D-glucose, the fatty acid utilization blocker methyl palmoxirate, or a combination of the two treatments, all at doses that stimulate food intake in laboratory rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Tonic immobility (TI) fear reactions and heterophil/lymphocyte (H/L) ratios were measured in individually caged Brown Leghorn pullets before and after their exposure to one of three procedures lasting approximately 72 hr. These were: ad lib feeding (controls), fasting (removal of food) or frustration of feeding (fasting plus denial of access to visible food). H/L ratios were elevated after fasting or frustration, illustrating the stressful nature of these procedures, but remained unaltered in the controls. Pretreatment TI responses were similar in all groups. Susceptibility and response duration were reduced upon retesting presumably through habituation, but this effect was relatively homogeneous across groups. Any direct effect of fasting/frustration upon fearfulness seemed unlikely because the mean TI responses of control and stressed birds were similar. However, whereas a rank order based on TI durations was repeatable upon retesting in the controls, it was destabilised in the stressed groups. Positive intraindividual correlations were found between pretreatment TI durations and subsequent H/L responses to fasting/frustration. This suggests that leucocytic responses to chronic stressors may be greater in fearful pullets than in less fearful birds.
AIMS: Exemestane (Aromasin) is an irreversible aromatase inactivator used for the treatment of postmenopausal women with advanced breast cancer. The objective of this study was to evaluate the effect of formulation comparing a sugar-coated tablet (SCT) with a suspension and food on the pharmacokinetics (PK) and pharmacodynamics (PD) with respect to plasma estrone sulphate (E1S) concentrations of exemestane, using a PK/PD approach. METHODS: This was an open, three-period, randomized, crossover study. Twelve healthy postmenopausal women received single oral doses of 25 mg exemestane as a SCT after fasting or food and as a suspension after fasting. Exemestane and E1S concentrations were determined before and up to 14 days after drug administration. Population analysis was performed in two steps: (i) a compartmental PK model was selected incorporating the effect of food and formulation; (ii) conditional on the PK model, a PD model was developed employing indirect response models. Model selection was performed using standard statistical tests. Validation and assessment of the predictive capability of the selected model was performed using real test data sets obtained from the literature. RESULTS: A three-compartment model with first-order elimination rate best described exemestane disposition (k12 0.454, k21 0.158, k13 0.174, k31 0.016 and k 0.738 h(-1)). Absorption was described by a mono-exponential function [ka 2.3 (SCT after fasting), 1.1 (SCT after food) and 7.6 h(-1) (suspension); lag time 0.2 h]. The PD model assumed that E1S plasma concentrations are determined by a zero-order synthesis rate (6.5 pg ml(-1) h(-1)) and a first-order elimination constant (0.032 h(-1)). Exemestane inhibited E1S synthesis with a C50 value of 22.1 pg ml(-1). The mean population estimates were used to simulate the administration of different doses of the drug (0.5, 1, 2.5, 5 and 25 mg day(-1)). The model predictions were in agreement with historical data. CONCLUSIONS: Exemestane absorption is influenced by the formulation of the drug and by food, but its disposition is independent of both. PK differences do no translate into clinically important differences in the PD. The PK/PD model developed was able to predict successfully the response to different doses and administration schedules with respect to oestrogen suppression.
Eighteen patients with New York Heart Association class III congestive heart failure were given single 100 mg oral doses of fenoldopam with food or fasting in a random-order single-blind crossover trial. Before and after each fenoldopam dose, thermodilution cardiac output, right atrial pressure, pulmonary artery pressure, and pulmonary capillary wedge pressure (PCWP) were measured with a balloon-tipped pulmonary artery catheter, and heart rates and blood pressures were recorded with an automated sphygmomanometer. Compared with fasting, bioavailability of fenoldopam was decreased significantly when administered with food: mean peak plasma fenoldopam level decreased from 26.5 (+/- 4.1 SEM) ng/ml to 10.9 (+/- 1.7 SEM) ng/ml (p = 0.0004) and mean area under the concentration-time curve was decreased from 44.7 (+/- 5.8 SEM) ng.hr/ml to 26.8 (+/- 4.1 SEM) ng.hr/ml (p = 0.0001). Fenoldopam administration to fasting patients resulted in decreases in mean arterial pressure, systemic vascular resistance, and PCWP and significant increases in cardiac index without change in heart rate. The maximum changes in mean cardiac index, systemic vascular resistance, and PCWP were greatest 1 hour after oral administration and did not persist beyond 3 hours after administration. In fasting patients, changes in cardiac index were correlated with plasma fenoldopam levels, whereas changes in PCWP and mean arterial pressure did not correlate significantly with the observed fenoldopam level.