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Biomedical subjects

R L Atkinson

Publications and source records attributed to R L Atkinson.

At least 91 records · Page 5Linked to original sources
PubMed1984

A comprehensive approach to outpatient obesity management.

Obesity is a predominantly physiological disorder that has a poor success rate of treatment. Recent evidence suggests that body weight is defended from change and that obese human beings regulate at a higher body weight than do lean human beings. A comprehensive program, including nutrition education, behavior modification, increased activity, and psychological support, has been developed at the University of Virginia Medical Center. The program is administered by dietitians and nurses under a physician's supervision. The major emphasis of the program is on weight maintenance. Several diet options are offered, with a very-low-calorie ketogenic diet being the most drastic. Analysis of the first 4 years of operation shows that 39% of all patients who had entered the program were still active (i.e., still returning for checkups); their average weight loss was 21.4 kg, and the average time in the program was 12.1 months. Inactive patients averaged a loss of 14.6 kg and 8.9 months in the program. Those results suggest that nonphysicians provide excellent obesity treatment at a lower cost than physicians. The use of multidisciplinary teams to treat obesity may be preferable to primary physician care.

Ambulatory Care↗
PubMed1983

Energy balance and regulation of body weight after intestinal bypass surgery in rats.

This study evaluated the possibility that intestinal bypass surgery alters energy balance and regulation of body weight. In two sets of experiments, male Sprague-Dawley rats underwent bypass or sham bypass surgery. In experiment 1, half of each group was overfed and half was underfed. Bypass reduced net calorie intake (intake - fecal loss) at 2 wk but not at 6 wk. Body weights were maintained at a much lower level in the bypass rats, yet apparent energy expenditure was greater. In experiment 2, bypass rats were compared with sham bypass and sham bypass who were food restricted for paired-weight-loss to bypass (PWL sham). Net calorie intake and body weights of bypass and sham bypass followed a similar pattern as in experiment 1. At similar levels of body weight postoperatively, bypass rats required more calories per kilogram than did the PWL shams, suggesting that bypass resets downward the level at which body weight is regulated. Calorie requirements correlated with food intake better than with absolute body weight. Further studies to determine the mechanism of altered energy expenditure may provide methods for weight loss without extensive surgery.

Animals↗
PubMed1983

Elevated pulse flow resistance in awake obese subjects with obstructive sleep apnea.

We measured resistance to air flow using the pulse technique in 5 normal subjects and in 12 male patients with obstructive sleep apnea while awake. At the end of an expiration, a constant flow pulse of 0.3 L/s of air was blown into a subject's mouth, while transpulmonary pressure and total transrespiratory pressure were recorded. Resistance was calculated by dividing the initial pressure step by the pulse flow rate. Nocturnal sleep studies were performed in patients with an ear oximeter, esophageal catheter, and face mask pneumotachometer; in the normal subjects, the studies were performed with an oximeter. A desaturation index was calculated by multiplying the average maximal percent desaturation during each apneic episode by the average number of desaturation episodes per hour of sleep. Transpulmonary and total transrespiratory system pulse flow resistance (RI and Rtot) were highly correlated with desaturation index (r = 0.94, p less than 0.001 and r = 0.88, p less than 0.001, respectively). The elevated pulse flow airway resistance in our patients may be caused by upper airway narrowing because of compression by fat, by lax tone in pharyngeal muscles, or by both. Measurements of RI and Rtot may be useful to detect and follow subjects with obstructive sleep apnea.

Adolescent↗
PubMed1983

Fluoroscopic and computed tomographic features of the pharyngeal airway in obstructive sleep apnea.

Because it has been suggested that patients with obstructive sleep apnea have a narrower pharyngeal airway than normal persons, we performed lateral fluoroscopy and computed tomographic (CT) scans of the pharynx in patients with this syndrome. Fluoroscopy in 6 sleeping patients showed that the obstruction always began during inspiration when the soft palate touched the tongue and posterior pharyngeal wall. The CT scans in 9 awake subjects demonstrated that the narrowest section of the airway in patients and in control subjects was the region posterior to the soft palate. The cross-sectional area of this region was significantly narrower in patients than it was in control subjects (p less than 0.001). Because a narrow airway would be more likely to collapse during inspiration than a normal one would (Bernoulli's Principle), we conclude that the narrow airways we observed in awake patients may be an important contributing factor in the pathogenesis of obstructive sleep apnea.

Adult↗
PubMed1983

The Prader-Willi syndrome: a study of 40 patients and a review of the literature.

Forty patients with the Prader-Willi syndrome have been examined. The typical features begin in gestational life with poor fetal vigor and difficulties with birth and post-partum feeding. The classical features of hypotonia, small hands and feet, cryptorchidism can be identified at this time. The delayed milestones, mental retardation and obesity become more prominent later. The average height of the patients in this series who were admitted to the Clinical Study Center was 149 cm and their weight was 114 kg. The weight and height curves show that Prader-Willi individuals are consistently shorter and heavier than normal children. Tests of endocrine function showed normal glucose tolerance. Insulin secretion was increased in relation to obesity. The rise in growth hormone (hGH) after injecting insulin to induce hypoglycemia and after the infusion of arginine was comparable to other obese individuals but was low in comparison to normal weight subjects. There was no rise in growth hormone with L-dopa administration, but there was a rise in hGH with the administration of 2-deoxy-D-glucose. The hypoglycemia produced by insulin was greater in the Prader-Willi patient than in obese controls. The rise in TRH (thyrotropin-releasing hormone) following the injection of TSH (thyrotropin stimulating hormone) was greater in the Prader-Willi patients than in the obese controls. Hypogonadism was routine in this series, and the response to LRH (luteinizing releasing hormone) was absent in all tested subjects. Treatment with clomiphene for 30 to 90 days significantly increased the response to LRH in three adult individuals who had not been treated with gonadal steroids previously and who were hypogonadal. Rectal temperature declined in three of the five Prader-Willi patients during exposure to an ambient temperature of 4 degrees C, but none of the three obese controls showed a decline. Food intake averaged 5167 kcal/d when six patients were given trays containing more food than they could eat. Food intake was not reduced when tryptophan was added to the diet. Salivary secretion was reduced in the Prader-Willi patients. A number of pulmonary function tests were significantly reduced in the study patients compared to obese or normal weight controls. The anatomic findings in four autopsied patients with the Prader-Willi syndrome showed no significant differences from those of obese subjects without this syndrome. The chromosomal pattern showed a deletion or translocation at chromosome 15 in 3 of 12 patients in whom this test was performed. These findings in 40 patients with the Prader-Willi syndrome have been compared with the information contained in 159 reports published in the medical literature.

Body Height↗
PubMed1982

Role of the small bowel in regulating food intake in rats.

This study tested the hypothesis that exposure of the lower intestine to nutrients decreases subsequent food intake. Eight male Sprague-Dawley rats underwent jejunoileal bypass surgery with 8 cm of proximal jejunum anastomosed to 5 cm of terminal ileum in an end-to-side fashion. Eight control rats had sham bypass surgery with similar intestinal incisions that were reanastomosed in normal continuity. Another group of eight rats underwent ileal transposition (IT). A 10-cm segment of terminal ileum was transected, leaving the mesentery and blood supply intact, and transposed to the jejunum 8 cm from the ligament of Treitz. Thus total intestinal length was intact. Eight control rats had similar intestinal transections reanastomosed in normal continuity. A similar pattern of decreased food intake in the first 1-2 wk occurred in both bypass and IT rats. The values were significantly different from the respective sham surgery control groups. Body weights decreased, but the fall was greater in bypass rats. These data suggest that partially digested food in the lower intestine decreases food intake.

Animals↗
PubMed1982

Appetite suppressant activity in plasma of rats after intestinal bypass surgery.

Male Sprague-Dawley rats with a jejunoileal bypass ate 32% less in the 1st h of refeeding after an overnight fast than did sham-bypass rats. Fasted recipients injected intraperitoneally with 6-7 ml of bypass plasma also ate 32% less (P less than 0.001) during the 1st h of refeeding than did recipients of sham-bypass plasma, but subsequent intake was not significantly different. Rectal temperature, hematocrit, white blood cell count, and percent polymorphonuclear leukocytes were not different between bypass and sham-bypass rats. A test for aversive conditioning suggested that the effect of bypass plasma was not due to illness or discomfort. These data suggest that intestinal bypass produces a transferable humoral factor that suppresses food intake and that the effect is not due to illness or discomfort. If the decreased food intake in humans after intestinal bypass is due to a similar mechanism, the possibility exists that this humoral appetite-suppressant factor may be clinically useful in the treatment of morbid obesity.

Animals↗
PubMed1982

The relationship of parthenogenetic development in Broad Breasted White turkey eggs to level of production and environmental factors.

One hundred and twenty Broad Breasted White turkey hens were taken through two production periods with a 10-week dark house treatment between cycles. Incidence of parthenogenesis was established on each virgin female prior to artificial insemination to determine fertility and hatch of fertile eggs. Following the dark house treatment, the hens were again checked for incidence of parthenogenetic development assuming that no viable spermatozoa remained in the oviduct. A number of environmental factors affecting the hens and their egg production were checked to determine the effect on parthenogenesis. There was a strong correlation between the incidence of parthenogenetic development in the two cycles. In addition, incidence of parthenogenetic development was correlated with low ambient temperature at time of ovulation. Parthenogenetic development had a heritability of .2 and a sizable genetic correlation with both production and hatch of fertile eggs. All other relationships showed little or no correlation.

Animals↗
PubMed1982

Intravenous lidocaine for the treatment of intractable pain of adiposis dolorosa.

Adiposis dolorosa (Dercum's disease) is a syndrome of painful adipose tissue which occurs most often in post-menopausal women and is associated with obesity, asthenia, and emotional disturbances. The etiology is uncertain, but is probably multifactorial. Numerous treatments to relieve the pain have generally been unsuccessful. A patient with adiposis dolorosa was treated with intravenous infusions of lidocaine over a two-year period. Relief from pain lasted from two to 12 months after each infusion. A single-blind placebo infusion did not relieve the pain. Lidocaine infusions did not relieve the pain of diabetic neuropathy or of angina in this patient. The mechanism of relief of pain of adiposis dolorosa by lidocaine is uncertain, but previously reported central effects of lidocaine suggest that alterations in the central nervous system may be responsible.

Adiposis Dolorosa↗
PubMed1982

Altered dietary preference for fat and sucrose after intestinal bypass surgery in rats.

We studied changes in dietary preference for sucrose and fat before and after intestinal bypass surgery or sham bypass surgery in Sprague-Dawley rats. During 6-d test periods before and after surgery, rats were offered both ground regular rat chow (chow) and ground chow adulterated with 20 percent fat as vegetable oil (Expt 1) or ground chow adulterated with 25 percent sucrose (Expt 2). A control group was fed only ground chow throughout (Expt 3). Before surgery in both experiments with adulterated chow, the rats preferred the fat or sucrose adulterated chow over regular chow by at least a 7:1 margin. After surgery, the bypass rats continued to prefer the adulterated diets, but by only 2.5:1 and 4:1 margins, respectively. The sham bypass rats continued their preoperative pattern of intake. Total calorie intake decreased by 25 percent to 36 percent in the bypass rats fed fat and sucrose chow. In both experiments the decrease came from decreased intake of the adulterated foods only. Bypass rats in the control group decreased food intake by only 9 percent. Sham bypass rats maintained their preoperative calorie intake and patterns of intake after surgery. Body weights of bypass rats decreased significantly compared to preoperative weights and compared to weights of the sham bypass rats. These data suggests that preference for both fat and sweet foods decreases in the initial period of rapid weight loss after bypass and this decreased preference may play a role in weight loss after bypass.

Animals↗
PubMed1981

Adrenergic modulation of glucagon and insulin secretion in obese and lean humans.

The adrenergic modulation of immunoreactive insulin (IRI) and glucagon (IRG) secretion was studied in 5 massively obese subjects hospitalized ion a metabolic ward. Epinephrine was infused alone or in combination with propranolol, a beta adrenergic blocking drug, or with phentolamine, an alpha adrenergic blocking drug. Epinephrine infusion produced a significant (p less than .02) rise in IRG levels which was blocked by addition of either phentolamine or propranolol. Pure alpha adrenergic stimulation with propranolol-epinephrine infusion inhibited IRG secretion (p less than .02). IRI levels decreased with propranolol-epinephrine infusion (p less than .02), increased with phentolamine-epinephrine infusion, and were not affected by infusion of epinephrine alone. Glucose concentrations rose with all 3 infusions but were less with phentolamine-epinephrine. A control group of 4 lean outpatients on a ad lib diet demonstrated a similar pattern but the changes of IRG secretion were smaller than in the obese subjects and were not statistically significant. We conclude that in obese humans IRI secretion is increased by beta adrenergic stimulation, is decreased by alpha adrenergic stimulation, and is unaffected by combined alpha and beta adrenergic stimulation. In contrast, IRG secretion is stimulated by combined alpha and beta adrenergic stimulation, is inhibited by pure alpha adrenergic stimulation, and is unaffected by pure beta adrenergic stimulation.

Adult↗
PubMed1981

Lipoprotein lipase activity in adipose tissue from obese human beings.

The activity of lipoprotein lipase (LPL) released from human adipose tissue was measured before and after an oral glucose load in obese (n = 8) and normal (n = 7) weight subjects. The enzymatic activity of LPL release from fat tissue by heparin rose significantly one hour after glucose in the normal subjects. There was no such rise in LPL in adipose tissue from obese subjects. Serum triglyceride, insulin and glycerol were higher in the obese than in the lean subjects.

Adipose Tissue↗
PubMed1981

Nonphysician supervision of a very-low-calorie diet. Results in over 200 cases.

Nonphysician nutritional therapists treated 234 obese patients with a 12-week behavioral modification, nutrition education program followed by up to 12 weeks on a very-low-calorie diet (VLCD). Mean weight decreased from 104.5 kg to 85.8 kg after 12 weeks on VLCD. Mean maximal weight loss for all patients was 17.2 kg. Blood pressure decreased from 133/86 to a low of 111/70 during VLCD. In 91 hypertensive patients, blood pressure fell from 145/95 to 128/81 after 12 weeks of VLCD. No serious side effects of VLCD were noted, although two patients developed mild cases of gout and one patient was taken off the fast when premature ventricular contractions were noted on ECG. Cost analysis reveals that physician care is almost three times as expensive as care by non-physician nutritional therapists. We conclude that the treatment of obesity should be performed by nutritional therapists under physician supervision using a comprehensive program of behavioral modification and VLCD.

Adolescent↗
PubMed1980

Effects of insulin at two dose levels on gluconeogenesis from alanine in fasting man.

We have determined the effect of insulin infused at 1 and 5 mU/kg/min on gluconeogenesis from alanine in 48-hr fasted men. The conversion of alanine to glucose was measured by the arterial-hepatic venous catheterization technique combined with the infusion of 14C-alanine. During insulin infusion, euglycemia was maintained by variable glucose infusion. When insulin was infused at 1 mU/kg/min the net splanchnic production of 14C-glucose was suppressed by 80% but glucagon infused at the end of the study resulted in substantial release of 14C-glucose from the liver suggesting marked accumulation of labeled glucose in glycogen. When insulin was infused at 5 mU/kg/min the splanchnic release of 14C-glucose was also markedly suppressed but in contrast to the lower insulin dose very little labeled glucose accumulated in glycogen. Neither the high nor the low dose insulin infusion had any effect on net splanchnic alanine uptake and plasma glucagon levels fell by 35% in both protocols. These data demonstrate that in 48-hr fasted man, (1) a small increment in insulin concentration will suppress glucose production but mostly by diverting the newly formed glucose into glycogen; (2) at higher concentrations, insulin will inhibit glucose production mainly by suppressing glucoeogenesis; and (3) this insulin-induced suppression of gluconeogenesis is due to an intrahepatic effect rather than an effect on the splanchnic extraction of alanine.

Alanine↗
PubMed1980

Insulin-induced insulin resistance of lipolysis in human adipocytes in organ culture.

Adipose tissue derived from open biopsies was used to develop a system for studying insulin resistance in human tissue in vitro. Subcutaneous adipose tissue obtained from obese donors was incubated in Parker's medium 199 in the absence or presence of insulin for 24 h under sterile conditions. Adipocytes were then isolated by collagenase digestion, washed thoroughly, and incubated for 2 h with multiple insulin concentrations in Krebs-Ringer phosphate buffer with 4% bovine serum albumin. Lipolysis was estimated by measuring glycerol. Basal lipolysis in adipocytes cultured with insulin did not differ significantly from that of adipocytes cultured without insulin (2.49 +/- 0.18 vs. 2.67+/- 0.58 mumol glycerol/mmol triglyceride). The maximum acute response in adipocytes prepared from tissue exposed to insulin during culture was 55% inhibition of basal lipolysis, whereas the maximum response in cells prepared from tissue not exposed to insulin chronically was 80%. Statistical analysis by paired t test showed a significant difference (P < 0.01) in the reaction of the two groups of cells to acute exposure to insulin. The insulin dose required to produce the half-maximal effect was increased from 3 to 24 microU/ml. Thus, after chronic exposure to insulin, adipocytes were not as responsive to the acute antilipolytic action of the hormone. We conclude that chronic exposure to insulin induces insulin resistance in human adipocytes.

Adipose Tissue↗