Regulation of energy balance.
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Adipose Tissue, Brown↗
Biomedical subjects
R Woo
Publications and source records attributed to R Woo.
The effect of increasing physical activity on voluntary food intake and energy balance.
Energy homeostasis with increased physical activity is dependent upon compensatory changes in intake. Results from metabolic balance studies in obese women indicate a dissociation of energy intake from that expended as exercise. Voluntary intake remained fixed at a sedentary level whether activity was added to or subtracted from total daily expenditure. The importance of physiological factors such as excess energy stores or psychological factors such as habit or sensory perceptions in obesity needs consideration.
Adult↗
Elevated postprandial insulin levels do not induce satiety in normal-weight humans.
To determine whether an elevated insulin level contributes to satiety, two experiments were conducted using a covert system of monitoring food intake. Normal-weight volunteers received intravenous infusion of either 0.15 M saline or a mixture of glucose and insulin during a single-course meal. In the first group, the glucose-insulin infusion (0.03 U insulin X kg-1 X h-1 and 0.25 g glucose X kg-1 X h-1) was begun 30 min before the start of the test meal and ended 15 min after subjects had voluntarily stopped eating. Plasma insulin was raised threefold, and glucose increased 20 mg/dl above preinfusion base line at time of eating. In the second group, the glucose-insulin mixture (insulin bolus of 12 mU/kg plus 0.03 U insulin X kg-1 X h-1 and 0.125 g glucose X kg-1 X h-1) was delivered 12 min after an appetizer was served and just as the test meal began. This infusion was stopped 12 min after the end of the meal. Serum insulin was fourfold higher than saline infusion levels at onset of eating, but glucose remained the same. The changes induced in these studies by the glucose-insulin infusions mimicked normal insulin and glucose levels seen shortly before satiation is complete in a meal. No effect on meal size or duration was observed. Therefore normal postprandial elevation of insulin is unlikely to signal satiety in humans.
Eating↗
Mobilization of triglyceride but not cholesterol or tocopherol from human adipocytes during weight reduction.
Adipocyte triglyceride, cholesterol, and tocopherol contents were examined in three human obese subjects, all over 150% of ideal weight, who were placed on weight reduction formula diets for 11, 21, and 25 wk, respectively. Body weight decreased from 77 to 63 kg, 188 to 147 kg, and 147 to 99 kg, respectively. All subjects had normal serum cholesterol and triglyceride levels, and these did not vary greatly during weight reduction. Subcutaneous fat was obtained at frequent intervals by needle aspiration from the buttocks before and during weight reduction. Adipocyte size was measured by osmium tetroxide fixation technique, tissue cholesterol content by GLC, tissue triglyceride content by lipid extraction, and tissue tocopherol by thin-layer chromatography. Initial adipocyte size was 0.54, 1.06, and 0.96 micrograms of lipid per cell, respectively (normal 0.60), and the mean cell size decrease during weight reduction was 40%, all due to triglyceride mobilization. Adipocyte cholesterol and tocopherol content did not change significantly during weight reduction. These data are consistent with the concepts that triglycerides but not cholesterol or tocopherol are mobilized from the fat cell during up to 6 months of weight reduction and that independent mechanisms control the efflux of these adipocyte constituents.
Adipose Tissue↗
Effect of exercise on spontaneous calorie intake in obesity.
The effect of increased physical activity on energy intake and balance was investigated in six obese women (mean 167% above ideal body weight) voluntarily hospitalized for metabolic balance studies. Three 19-day treatments-one sedentary and two with treadmill exercise which increased daily expenditure to 110% (mild) and 125% (moderate) of sedentary expenditure-were imposed on each subject. Individual daily expenditure and ad libitum intake were determined by activity diaries and covert monitoring, respectively. Subjects selected and did not not change an intake level which allowed for energy balance during the sedentary period only. Therefore, the difference between intake and expenditure between treatments was significantly different (sedentary 11, mild -114, and moderate -369 kcal/day). The negative balance observed with mild and moderate exercise was obtained because while expenditure was raised with exercise, no compensatory increase in intake occurred. Moderate, realistic levels of activity did not regulate intake.
Adult↗
Voluntary food intake during prolonged exercise in obese women.
The effect of 57 days of moderate physical activity on the energy intake and balance of three obese women (187% of ideal weight) was investigated in a metabolic balance study. Food was offered in extra quantity, prepared in a palatable but simple fashion, and intake was covertly monitored. Expenditure was measured using the factorial method and indirect calorimetry done every 3 to 4 days. After a 5-day evaluation phase which no exercise was done, individual treadmill assignments were given to subjects to increase daily expenditure to 125% of sedentary levels. Mean dialy intake (1903 kcal/day) and expenditure (2882 kcal/day) did not change with time. As a result, negative energy balance was obtained and sustained. A consistent rate of weight loss (0.12 kg/day) at a reasonable cost (8200 kcal/kg)occurred. Therefore, obese women doing long-term moderate exercise do not compensate by an increase in caloric intake. This can produce a negative caloric balance when exercise is coupled with ad libitum selection of ordinary foods.
Adolescent↗
Normal responses of rats with transplanted neonatal islets to stress, epinephrine, and cortisol.
Sympathetic responses were evaluated in rats transplanted with neonatal pancreatic tissue. Transplantation was by one of two methods: mild collagenase digestion with subsequent intraportal injection, or direct placement of intact pancreatic tissue under the renal capsule. Compared with control intact animals, both groups of transplanted rats reverted to normal fasting and postglucose load plasma glucose and insulin. The hyperglycemia characteristic of stress or of injected exogenous epinephrine was present and similar in all three groups. The response to an intragastric glucose load or to tolbutamide injection during stress was similar in transplanted and in control animals. All three groups of rats responded to sustained cortisol injection with a compensatory hyperinsulinemia but maintained normal plasma glucose, water intake, and urine volume. No evidence could be detected in this study of an exaggerated "denervated" response of the transplanted islets. The normal sympathetic responses of these neonatal islet preparations in which little or no collagenase was used, in comparison with the abnormal responses previously reported for collagenase-treated individually isolated adult rat islets, suggest differences in recuperative powers of the sympathetic innervation in islets, possibly related to age and to method of preparation of transplanted tissue.
Animals↗
Biliary clonorchiasis.
Parasitic infection of the biliary tree may be seen more frequently because of changing patterns in travel, and may come to the attention of the surgeon when obstruction or secondary bacterial infection occurs. In this case, intraoperative cholangiography indicated common duct abnormalities, and choledochotomy led to the diagnosis of Clonorchis sinensis. A recommendation is made to follow up patients with bilary parasite infections to determine the long-term sequelae.
Adult↗
Selection of a practical method of pancreatic islet transplantation in the rat.
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Animals↗
The effect of pediatric orthopaedic experience on interobserver and intraobserver reliability of the herring lateral pillar classification of Perthes disease.
An analysis was done of the effect of surgeons' pediatric orthopaedic experience on the classification of Perthes disease according to the lateral pillar classification described by Herring. Five observers with varied pediatric orthopaedic experience reviewed anteroposterior (AP) pelvis radiographs of 33 patients in the fragmentation phase of Perthes disease and classified each case on three separate occasions at least 24 hours apart. Frog-leg lateral-view radiographs taken at the same time were also classified using the same criteria based on the femoral head anterior column. Kappa statistics showed good agreement for intra- and interobserver reliability of classification for both AP and frog lateral radiographs. There were no statistically significant variations among the reviewers. Twenty-four percent of the cases had a classification one grade worse on the lateral radiograph compared to the AP view. The lateral pillar classification provides a reproducible radiographic technique for Perthes disease characterization independent of pediatric orthopaedic experience.
Adolescent↗