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Biomedical subjects

J C Melchior

Publications and source records attributed to J C Melchior.

At least 19 recordsLinked to original sources
PubMed1991

Lack of plasmic beta-endorphin response to a gastronomic meal in healthy humans.

In order to study the relationship between the endogenous opiate system and food intake in man, plasma concentrations of beta-endorphin were measured in ten healthy subjects. Time course of beta-endorphinemia was compared under the following conditions: basal (fasting), after an injection of pentagastrin (6 micrograms/kg), or after a gastronomic meal. No changes in plasma beta-endorphin or ACTH concentrations were observed with pentagastrin nor after the meal, despite the combination of very high sensory pleasure with intake of a very large amount of food. It is concluded that blood beta-endorphin concentration is not a sensitive index of the effects of food intake on the endogenous opioid system in man.

Adult↗
PubMed1991

Immunoreactive beta-endorphin increases after an aspartame chocolate drink in healthy human subjects.

It has been claimed that sucrose intake induces a rise in beta-endorphins. In an attempt to discriminate between the sensorial and metabolic effects of sucrose intake in this process, the effects of two chocolate drinks were compared: one sweetened with 50 g of sucrose, the other with 80 mg of aspartame. Plasma beta-endorphin concentrations were more elevated after the aspartame drink than after sucrose or fasting, while insulin increased after drinking as much with aspartame as with sucrose. We suggest that the increase in beta-endorphin after aspartame edulcorated chocolate is related with insulin secretion in the absence of marked changes in blood glucose or with a direct effect of aspartame itself on beta-endorphin liberation.

Adolescent↗
PubMed1991

A kappa opiate agonist, U50,488H, enhances energy expenditure in rats.

The effect of U50,488H (a selective kappa opiate agonist) on oxygen consumption was measured in either resting and free-moving rats. In both states, U50,488H provokes an increase in oxygen consumption. In resting rats, the increase occurs at lower doses than in free-moving rats. The explanation could be that in the free-moving rats the drug results in an increase in energy expenditure, partially compensated by a decrease in activity.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1991

Resting energy expenditure is increased in stable, malnourished HIV-infected patients.

Resting energy expenditure (REE) was measured by reference to body composition in 50 malnourished patients with human immunodeficiency virus (HIV) infection and compared with that of 14 healthy subjects. Among HIV patients, 40 had acquired immune deficiency syndrome (AIDS) and 10 had AIDS-related complex (ARC). All were in stable condition and had a previous history of progressive wasting, ie, a mean body weight loss of 14.2 +/- 8.1 kg over 16.6 mo (range 2-49 ms). The mean REE was 14% higher than estimated basal energy expenditure (EBEE), according to the Harris and Benedict formula. Thirty-four patients (68%) were classified as hypermetabolic (REE greater than 110% EBEE). The best predictable variable for REE was fat-free mass (FFM), as determined by an anthropometric method (r = 0.72; P less than 0.001). The mean REE was 12% higher in HIV patients than in the control group FFM (156 +/- 19 vs 124 +/- 17 kJ.kg FFM-1.d-1). We concluded that in stable and malnourished HIV patients, the progressive wasting may be partly related to an increase in REE. The mechanism of this hypermetabolic state remains to be established.

Body Composition↗
PubMed1991

Energy-metabolism adaptation in obese adults on a very-low-calorie diet.

In this study, six obese women received a very-low-calorie diet (VLCD) for 3 wk. At day 0, body composition was assessed with a bioelectric impedance analyzer. The evolution in lean body mass (LBM) during the VLCD was estimated from nitrogen balance, measuring urine and fecal losses and taking into account skin, nitrate, and menstrual losses to avoid underestimation bias that could explain the decreased ratio of resting metabolic rate (RMR) to LBM previously reported. RMR was measured at days 0, 3, 5, and 21. The RMR-LBM ratio declined significantly during the VLCD period and decreased faster during the first week; the day 3, day 5, and day 21 ratio values were 94%, 91%, and 82%, respectively, of the original. The RMR-LBM ratio decrease after 21 d of a VLCD was near that found in chronic undernutrition. Results of previous studies that did not find any drop in the RMR-LBM ratio in obese adults on VLCDs might be explained by their LBM-assessment methods.

Adaptation, Physiological↗
PubMed1990

Negative allesthesia and decreased endogenous opiate system activity in anorexia nervosa.

The combined effects of an intragastric load of glucose compared to water and of naltrexone compared to placebo were tested on preference for sucrose in six anorectic patients. While in normal subjects, glucose-induced negative allesthesia is known to disappear upon loss of weight, it persisted in anorexia nervosa (AN) despite a major weight loss; furthermore, in contrast with its effects in normoponderal subjects, naltrexone at the dose of 25 mg did not decrease the preference for sucrose nor did it enhance glucose-induced allesthesia. Basal plasma beta endorphin level determined by radioimmunoassay was higher in AN than in normal subjects (75 +/- 6.1 pmoles/l vs. 13 +/- 3.8 pmoles/l) (p less than 0.001). It is suggested that a decrease in endogenous system opiate activity might be associated with food refusal and body weight loss in anorexia nervosa.

Adolescent↗
PubMed1989

Effects of a low dose of naltrexone on glucose-induced allesthesia and hunger in humans.

In order to study the effects of a low dose of the opioid antagonist naltrexone on ingestive behavior for sucrose in humans, preference for sucrose solutions and feelings of hunger were scored on visual analogical scale by 14 healthy subjects with or without naltrexone. Effects of intragastric glucose load or water, and naltrexone (25 mg) or placebo were tested. At this low dose, naltrexone alone had a slight effect on allesthesia, and it produced a strong potentiation of glucose-induced allesthesia.

Adult↗
PubMed1989

[Anorexia nervosa: absence of sensitivity to nutritional protein markers. Study of 23 patients and comparison to a paired group with colonic Crohn's disease].

One of the most important therapeutic goal in anorexia nervosa is to define with the patient a body weight to obtain. To do so, objective criteria are needed. For this purpose, we studied in a longitudinal way, 9 nutritional parameters in 23 patients with anorexia nervosa, as compared with 23 age - and sex - matched patients with Crohn's disease: body weight, tricep's skinfolds, mid-arm muscle circumferences; serum albumin, prealbumin, transferrin, hemoglobin, cholesterol; urinary creatinine and calcium, magnesium, zinc and copper serum levels and urinary outputs. Despite losses of body weight, of lean body mass and of fatty mass higher in patients with anorexia nervosa than in those with Crohn's disease, the former had higher nutritional protein's serum levels than the latter. These nutritional protein markers were not in anorexia nervosa different from normal values. In anorexia patients, zinc and copper serum levels and urinary outputs were very low. This study suggests that nutritional protein markers of hepatic synthesis are not sensitive markers for malnutrition evaluation and can not be used to follow renutrition efficacy.

Adult↗
PubMed1989

Energy expenditure economy induced by decrease in lean body mass in anorexia nervosa.

In anorexia nervosa, the low energy input associated with the classic overactivity during the malnourished state needs a sparing of energy expended at rest and also during physical activity. Therefore, we measured energy expenditure, both at rest and during moderate bicycling exercise (30W, 6 min), in 11 adult anorectic patients (weight 35.15 +/- 4.30 kg, mean +/- s.d.) at the beginning of their treatment and again after a mean weight gain of about 8.4 kg. During the malnourished state, the resting energy expenditure (REE) was lower than that predicted according to Harris and Benedict (P less than 0.001). Although it was significantly increased after weight gain (P less than 0.05), the REE per kg of lean body mass remained unchanged after repletion. The total oxygen consumption related to exercise remained unchanged after refeeding (2114 +/- 487 ml/15 min, basal vs 2168 +/- 394 ml/15 min, repletion) (n.s.). Thus in anorexia nervosa, weight loss and malnutrition did not induce economy either in energy expended at rest per unit of lean body mass nor in the energy expended in moderate cycling activity.

Adolescent↗
PubMed1987

Hemodynamic effects of continuous norepinephrine infusion in dogs with and without hyperkinetic endotoxic shock.

We compared, at constant preload maintained by polygeline (gelatin) infusion, the hemodynamic effects of continuous infusion of norepinephrine (0.5, 1, and 1.5 micrograms/kg X min) in anesthetized dogs with and without hyperdynamic endotoxic shock. In both groups, norepinephrine infusion increased systolic, diastolic and mean aortic BP, cardiac index, stroke index, index of myocardial contractility, and mean pulmonary artery pressure. No significant change in right atrial pressure, left ventricular end-diastolic pressure, heart rate, systemic vascular resistance, or pulmonary vascular resistance was observed. Oxygen consumption index and oxygen extraction ratio remained unchanged. Increases in systolic aortic BP were dose-related, whereas maximal effects on other variables were obtained at 0.5 to 1 microgram/kg X min. The rise in aortic pressure resulted from an increased cardiac index but not from an increased systemic vascular resistance. Stroke index increased as contractility improved. The slight alpha-adrenergic effect of continuous, low-dose norepinephrine infusion did not impede the beneficial effects of the marked beta-adrenergic stimulation on cardiac function. The combination of these two effects improved hemodynamic disturbances of hyperdynamic endotoxic canine shock.

Animals↗
PubMed1987

Rapid gas-chromatographic assay of bupivacaine in plasma.

A method for estimating bupivacaine concentration in human plasma by capillary gas-chromatography using solid injection and nitrogen-specific detection is described. Etidocaine, another anilidetype local anesthetic was used as internal standard and added to the sample before single-step extraction with diethylether. This method demonstrates high sensitivity (6 ng/ml plasma) and combines selectivity, rapidity, and simplicity. Results of this procedure correlate well with those obtained by an HPLC method.

Bupivacaine↗
PubMed1987

[Analysis of factors related to early mortality in digestive hemorrhage caused by portal hypertension].

In order to determine immediate criteria of prognosis for patients with portal hypertension hospitalized for digestive hemorrhage, in an intensive care unit, 18 variables were recorded during the 24 hours following admission in 65 patients. Data related to death were age, ascites, hepatic encephalopathy, shock, active hemorrhage, acute pneumonia, decrease in prothrombin time, use of esophageal balloon tamponade, use of mechanical ventilation, number of red blood cell units transfused. Discriminant analysis yielded a linear combination of 4 variables which best separated survivors from non survivors with the following equation: F = 0.330 X hepatic encephalopathy + 0.433 X shock + 0.226 X active hemorrhage + 0.0097 X age - 0.396. The threshold decision of the hemorrhage prognosis index (HPI) was F = 0.57; 80 p 100 of all patients were correctly classified. In order to be validated, HPI was compared with a general (SAPS) and specific (Pugh's classification) scoring system, in a prospective study of 57 episodes of digestive hemorrhage. In this study, sensitivity was better with HPI than with SAPS (0.70 versus 0.45), specificity was higher with HPI than with Pugh's classification (0.86 versus 0.70). Percentage of correctly classified patients was higher using HPI (81 p. 100) than SAPS (77 p. 100) and Pugh's classification (68 p. 100). We suggest that the HPI, determined with 4 easily defined and recorded variables should be used prospectively to compare efficacy of different treatments.

Adult↗
PubMed1986

What changes can be expected during high frequency jet ventilation when the rate of ventilation, the I:E ratio and the driving pressure are modified? A laboratory study.

Changes in minute ventilation, tracheal airway pressure and lung volume have been measured using a jet ventilator (VS 600) during different rates of ventilation, I:E ratios and driving pressures. A lung model with a slightly increased compliance and an increased airway resistance was used. Five rates of ventilation (from 60 to 230 b.p.m.), three I:E ratios (0.25, 0.43, 0.67) and three driving pressures (200, 300 and 400 kPa) were studied. The increases in the rate of ventilation did not modify minute ventilation significantly, decreased peak airway pressure only slightly and increased end-expiratory pressure and lung volume. The increases in I:E ratio produced increases in minute ventilation, peak airway pressure, end-expiratory pressure and lung volume. The increases in driving pressure induced changes similar to those produced by the alterations in I:E ratio.

Airway Resistance↗
PubMed1985

Circulatory responses to thiopentone and tracheal intubation in patients with coronary artery disease. Effects of pretreatment with labetalol.

The haemodynamic responses to induction and tracheal intubation have been studied in patients with coronary artery disease randomly assigned to a labetalol pretreatment group (n = 14) or to a placebo group (n = 16). Twelve hour before operation, treated patients received a bolus dose of labetalol 0.5 mg kg-1 followed by a constant infusion of 0.1 mg kg-1 h-1 i.v. Anaesthesia was induced with thiopentone and phenoperidine, and intubation performed following the administration of suxamethonium. At intubation, the changes in heart rate (P less than 0.01), mean arterial pressure (P less than 0.05) and rate-pressure product (P less than 0.01) were significantly smaller in the labetalol group compared with the placebo group. Labetalol pretreatment appears satisfactory and may be useful in patients with coronary artery disease who have a normal left ventricular ejection fraction.

Anesthesia, General↗