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Biomedical subjects

C W le Roux

Publications and source records attributed to C W le Roux.

13 recordsLinked to original sources
PubMed2006

Progressive rise in gut hormone levels after Roux-en-Y gastric bypass suggests gut adaptation and explains altered satiety.

BACKGROUND: Bariatric surgery is the most effective treatment for achieving long-term weight loss in morbidly obese patients. This study investigated prospective changes in gut hormones and metabolic indices after Roux-en-Y gastric bypass (RYGB). METHODS: Six patients were seen before, and at 1, 3 and 6 months after operation. Blood was collected after a 12-h fast and at regular intervals after a mixed 420-kcal meal. Hormonal responses were determined, and comparisons between basal levels and areas under the curve were made. Visual analogue scores were used to assess satiety, hunger and nausea. RESULTS: Mean body mass index decreased from 48.3 kg/m(2) before surgery to 36.4 kg/m(2) 6 months after RYGB. This was accompanied by a decrease in fasting leptin (P < 0.001) and insulin (P = 0.021) levels. At 1, 3 and 6 months after operation, progressively increasing peptide YY (P < 0.001), enteroglucagon (P = 0.045) and glucagon-like peptide 1 (P = 0.042) responses were observed. There was no change in fasting ghrelin levels (P = 0.144). Postprandial satiety was significantly increased by 1 month after surgery and this was maintained until the end of the study (P < 0.001). CONCLUSION: RYGB resulted in substantial weight loss with enhanced postprandial satiety, a sustained weight plateau, and proportionate reduction in fasting insulin and leptin levels. Lack of the expected increase in appetite and food intake as components of a counter-regulatory response may be explained by gut adaptation and the consequent graded rise in the levels of gut hormones that promote satiety.

Adaptation, Physiological↗
PubMed2005

Attenuated peptide YY release in obese subjects is associated with reduced satiety.

The responses of the gut hormone peptide YY (PYY) to food were investigated in 20 normal-weight and 20 obese humans in response to six test meals of varying calorie content. Human volunteers had a graded rise in plasma PYY (R2 = 0.96; P < 0.001) during increasing calorific meals, but the obese subjects had a lower endogenous PYY response at each meal size (P < 0.05 at all levels). The ratio of plasma PYY(1-36) to PYY(3-36) was similar in normal-weight and obese subjects. The effect on food intake and satiety of graded doses of exogenous PYY(3-36) was also evaluated in 12 human volunteers. Stepwise increasing doses of exogenous PYY(3-36) in humans caused a graded reduction in food intake (R2 = 0.38; P < 0.001). In high-fat-fed (HF) mice that became obese and low-fat-fed mice that remained normal weight, we measured plasma PYY, tissue PYY, and PYY mRNA levels and assessed the effect of exogenous administered PYY(3-36) on food intake in HF mice. HF mice remained sensitive to the anorectic effects of exogenous ip PYY(3-36). Compared with low-fat-fed fed mice, the HF mice had lower endogenous plasma PYY and higher tissue PYY but similar PYY mRNA levels, suggesting a possible reduction of PYY release. Thus, fasting and postprandial endogenous plasma PYY levels were attenuated in obese humans and rodents. The PYY(3-36) infusion study showed that the degree of plasma PYY reduction in obese subjects were likely associated with decreased satiety and relatively increased food intake. We conclude that obese subjects have a PYY deficiency that would reduce satiety and could thus reinforce their obesity.

Animals↗
PubMed2005

Ghrelin does not stimulate food intake in patients with surgical procedures involving vagotomy.

CONTEXT: Patients with gastric or esophageal surgery and transection of the vagus nerve may suffer from appetite and weight loss but without dysphagia or mechanical obstruction to eating. The gastric hormone ghrelin stimulates food intake and GH release in rodents and man. However, rodents with vagotomy are not sensitive to the feeding effects of ghrelin. OBJECTIVE: The objective of the study was to determine whether humans with vagotomy are sensitive to ghrelin. STUDY DESIGN: The design was a double-blind, randomized, placebo-controlled trial. SETTING: This was a hospital-based study. PATIENTS: Six men and one woman who all had a previous complete truncal vagotomy with lower esophageal or gastric surgery entered and completed the study. INTERVENTION: Each patient received 120-min infusions of saline, 1 pmol/kg.min ghrelin, and 5 pmol/kg.min ghrelin on 3 separate days. After 90 min, a buffet meal was served. MAIN OUTCOME MEASURE: Energy intake at the buffet meal was measured. RESULTS: Ghrelin-stimulated GH release in a dose-dependent manner was measured, confirming bioactivity. However, no change in energy intake was observed with either dose of ghrelin [energy intake (kilojoules): saline 2805 +/- 812; ghrelin 1 pmol/kg.min, 2486 +/- 767; ghrelin 5 pmol/kg.min, 2382 +/- 543; P = not significant]. CONCLUSIONS: Ghrelin is unlikely to be an effective appetite-stimulatory treatment for patients with vagotomy and esophageal or gastric surgery. Our results suggest that an intact vagus nerve may be required for exogenous ghrelin to increase appetite and food intake in man.

Aged↗
PubMed2005

Peptide YY, appetite and food intake.

Obesity is taking on pandemic proportions. The laws of thermodynamics, however, remain unchanged, as energy will be stored if less energy is expended than consumed; the storage is usually in the form of adipose tissue. Several neural, humeral and psychological factors control the complex process known as appetite. Recently, a close evolutionary relationship between the gut and brain has become apparent. The gut hormones regulate important gastrointestinal functions such as motility, secretion, absorption, provide feedback to the central nervous system on availability of nutrients and may play a part in regulating food intake. Peptide YY (PYY) is a thirty-six amino acid peptide related to neuropeptide Y (NPY) and is co-secreted with glucagon-like peptide 1. Produced by the intestinal L-cells, the highest tissue concentrations of PYY are found in distal segments of the gastrointestinal tract, although it is present throughout the gut. Following food intake PYY is released into the circulation. PYY concentrations are proportional to meal energy content and peak plasma levels appear postprandially after 1 h. PYY3-36 is a major form of PYY in both the gut mucosal endocrine cells and the circulation. Peripheral administration of PYY3-36 inhibits food intake for several hours in both rodents and man. The binding of PYY3-36 to the Y2 receptor leads to an inhibition of the NPY neurones and a possible reciprocal stimulation of the pro-opiomelanocortin neurones. Thus, PYY3-36 appears to control food intake by providing a powerful feedback on the hypothalamic circuits. The effect on food intake has been demonstrated at physiological concentrations and, therefore, PYY3-36 may be important in the everyday regulation of food intake.

Appetite↗
PubMed2004

Postprandial plasma ghrelin is suppressed proportional to meal calorie content in normal-weight but not obese subjects.

Circulating levels of the gastric hormone ghrelin rise before and decrease after a meal. In normal-weight subjects, postprandial suppression of ghrelin is proportional to calories consumed. Obese individuals have lower fasting ghrelin levels; however, it is unclear whether the obese show normal postprandial suppression. This study aimed to compare postprandial ghrelin responses in normal-weight and obese subjects, using mixed macronutrient meals with varied fat and calorie content. Postprandial ghrelin response was measured in normal-weight insulin-sensitive subjects and obese insulin-resistant subjects, after six test meals with different fat and calorie content (250-3000 kcal). Increasing the calorie content of meals in normal-weight subjects progressively lowered nadir levels of ghrelin. The obese had lower fasting ghrelin levels, and the reduction after the consumption of all test meals was less than the normal-weight subjects. The lowest postprandial levels in the obese were no different to the nadir in normal-weight volunteers after 1000-, 2000-, and 3000-kcal meals. Thus, circulating ghrelin levels decreased in normal-weight subjects after mixed meals. Obese subjects demonstrated a much reduced ghrelin postprandial suppression. This reduced suppression may influence satiety, thus reinforcing obesity.

Energy Intake↗
PubMed2004

A new antiglycolytic agent.

BACKGROUND: Glycolysis is not completely or predictably inhibited by the glucose preservative currently in use, with glucose values falling by as much as 0.5 mmol/L during a 2-4-h period after sample collection. Immediate centrifugation of all samples is also impractical and therefore misdiagnosis of disease can occur, especially if more emphasis is being placed on fasting glucose for the diagnosis of diabetes. METHODS: Glycolysis at room temperature was evaluated over time using glyceraldehyde alone as well as in conjunction with standard antiglycolytic agents. RESULTS: Glyceraldehyde alone does not inhibit glycolysis completely. The combination of 11 mmol/L glyceraldehyde, 119 mmol/L sodium fluoride and 21.7 mmol/L potassium oxalate gave the best antiglycolytic results. The glucose values measured in samples stored at room temperature for 48 h was no different from those measured in samples centrifuged immediately after venepuncture and this is clinically superior to conventionally used sodium fluoride and potassium oxalate. CONCLUSION: Plasma glucose concentrations obtained from blood collected into tubes containing glyceraldehyde, sodium fluoride and potassium oxalate will more closely reflect those of the patient at venepuncture.

Blood Glucose↗
PubMed2003

Free cortisol index is better than serum total cortisol in determining hypothalamic-pituitary-adrenal status in patients undergoing surgery.

Serum total cortisol has traditionally been used for the interpretation of tests of the hypothalamic-pituitary-adrenal axis. Approximately 80% of total cortisol is bound to cortisol-binding globulin (CBG), and variation in CBG significantly affects serum total cortisol levels. Reliable assessment of hypothalamic-pituitary-adrenal axis reserve is difficult in severely ill patients, because CBG falls substantially during the acute phase response. The free cortisol index (FCI), defined as the ratio of total cortisol/CBG, correlates well with serum free cortisol. We evaluated the FCI in the context of severe stress and the acute phase response by measuring total cortisol and CBG pre- and postoperatively in 31 patients undergoing major elective surgery. Serum total cortisol increased by 55% from 453 +/- 35.2 (mean +/- SEM) nmol/liter (range, 88-882) to 700 +/- 47.2 (range, 294-1631) nmol/liter. Serum CBG decreased by 30% from 45 +/- 1.7 (range, 26.6-64.1) to 31.4 +/- 1.62 (range, 16.1-51.9) mg/liter, but FCI increased by 130% from 10 +/- 0.8 (range, 2-18) to 23 +/- 1.7 (range, 13-58) nmol/mg. In seven patients (23%), postoperative serum total cortisol was less than 500 nmol/liter, but their postoperative CBG levels were significantly lower than levels in the rest of the group (P < 0.01). However, there was no difference in the FCI between this subgroup and the rest of the group. This study demonstrates the importance of CBG measurement and the calculation of FCI for the interpretation of serum total cortisol in situations where CBG changes significantly.

Adrenal Glands↗
PubMed2003

Clinical authorization: what is best for the patient?

In this issue, Prinsloo and Gray report the results of a 137-laboratory audit on clinical authorization using the guidelines and standards from the Royal College of Pathologists. Only 33% of laboratories were found to be compliant with the standards, although many showed evidence of good practice. Clinical authorization is resource-hungry and the question raised by this study is whether adhering to the letter of the standards set by the Royal College of Pathologists is actually in the best interest of the patient and provides overall value for money, when the latter is key to optimizing the quality of service.

Chemistry, Clinical↗
PubMed2002

Growth hormone replacement does not increase serum prostate-specific antigen in hypopituitary men over 50 years.

OBJECTIVE: Epidemiological studies have shown an increased risk for prostate carcinoma in men with serum IGF-I in the upper part of the age-related reference range. Recombinant human GH (rhGH) is widely used in patients with GH deficiency, usually raising the serum IGF-I levels into the normal range: safety surveillance is therefore mandatory, with particular regard to neoplasia. The aim was to examine whether rhGH replacement in hypopituitary adults is associated with changes in serum prostate-specific antigen (PSA) as a surrogate marker of changes in prostatic growth. DESIGN AND METHODS: A prospective longitudinal study was used with a median follow-up of 22 (range 2.5-32) months, in which 41 men aged over 50 years with adult onset hypopituitarism and GH deficiency during rhGH replacement were examined. Serum PSA and IGF-I were measured at baseline and at latest follow-up. RESULTS: Mean serum PSA remained unchanged during rhGH replacement, with a median follow-up of 2 years. No correlation was found between the individual changes in serum IGF-I and changes in serum PSA. CONCLUSIONS: These data are reassuring thus far regarding the safety of GH replacement in relation to the prostate in this patient group.

Aged↗