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A Le Quellec

Publications and source records attributed to A Le Quellec.

At least 37 records · Page 2Linked to original sources
PubMed1996

Colonic fermentation and proximal gastric tone in humans.

BACKGROUND & AIMS: Some carbohydrates escape small intestinal absorption, and their presence in the ileum can affect proximal gut motility. Carbohydrates reaching the colon can inhibit gastric and pancreatic secretions. The hypothesis of this study was that colonic fermentation products of carbohydrates (short-chain fatty acids [SCFAs]) affect proximal gut motility and especially gastric tone. METHODS: Healthy volunteers were studied after oral administration of 20 g lactulose (n = 6) and intracolonic infusions of 20 g lactose (n = 7) and SCFAs (54 mmol/180 mL and 90 mmol/180 mL, respectively). Gastric tone (electronic barostat) and H2 concentrations in exhaled air were simultaneously monitored, and peripheral intestinal peptide levels were measured by specific radioimmunoassays. RESULTS: After oral lactulose administration (but not after saline), a significant decrease in gastric tone was observed, which rapidly followed the increase in H2 concentrations. Gastric tone also decreased after intracolonic infusions of both lactose and SCFAs; the most marked effect occurred after the highest SCFA dose. No significant changes in the level of plasma oxyntomodulin-like immunoreactivity and glucagon-like peptide 1 were found, whereas the level of peptide YY increased significantly over time, but not differently after saline and test solutions. CONCLUSIONS: Colonic fermentation of undigestible carbohydrates can inhibit gastric tone, and SCFAs may be responsible for this colonic brake. The role of intestinal peptides, if any, was not identified.

Adult↗
PubMed1995

Microdialysis probes calibration: gradient and tissue dependent changes in no net flux and reverse dialysis methods.

Probe calibrations are required for accurate estimations of extracellular concentrations in microdialysis experiments. Several methods have been developed and validated for in vivo determination of dialysis membrane recovery such as the perfusion rate method and the No Net Flux method. In this study, the No Net Flux and the reverse dialysis methods were investigated. Both measure the net transport of drug across the dialysis membrane. The recovery was defined as R = (Cin - Cout)/Cin, where Cin and Cout were the concentrations of a compound in the perfusate and in the dialysate, respectively. First, the accuracy of the No Net Flux method to estimate in vivo recovery was compared in two situations: diffusion from the probe into the dialysis medium and diffusion from the outer medium into the probe. The point of no net transport was used to estimate the concentration surrounding the probe. Neither difference between extracellular concentrations (intercept values) nor difference between recoveries were observed. Then the reverse dialysis method was tested to estimate the relative loss of drug from the perfusate when the probe was placed in a drug-free medium. Finally comparisons of the behavior of the drug diffusion across the membrane under increasing gradient conditions have shown an asymptotic profile, specific of the tissue; blood, muscle, and adipose tissue. The faster a drug was removed by microvascular transport (blood > muscle > adipocytes), the higher was the recovery, until the perfusate concentration reached a threshold value where the transport process became gradient limited and no more tissue limited.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Microdialysis: an alternative for in vitro and in vivo protein binding studies.

The aim of the present study was to compare the performance of conventional equilibrium dialysis method with a microdialysis method in studying drug protein binding. The two methods were assessed by comparing the measured mean unbound drug fraction in different plasma species in vitro in plasma of four different species and at two concentrations of the non-indolic melatonin analog S 20098. For the microdialysis study, the unbound drug fraction was calculated after correction for membrane recovery. Plasma protein binding of S 20098 ranged from 75 to 95%. In humans, rabbits and rats (10 ng/ml), equal unbound percentages were found between equilibrium dialysis and microdialysis. Microdialysis gave slightly but significantly higher values in rat (2000 ng/ml), and in monkey plasma independent of the drug concentration. Microdialysis was also performed in vivo in freely moving rats under steady-state conditions, yielding similar unbound fraction values (26.0 +/- 0.9%) to those obtained using microdialysis probes in rat plasma in vitro (24.4 +/- 1.6%). These results support the use of in vivo microdialysis in pharmacokinetic studies in freely moving animals.

Acetamides↗
PubMed1994

Indocyanine green pharmacokinetics in rats with progressive carbon tetrachloride-induced hepatocellular insufficiency.

Indocyanine green (ICG, CAS 3599-32-4) kinetics were used to assess hepatic function in rats with progressive hepatic disease induced by carbon tetrachloride administered by two different routes (intragastric and intraperitoneal). Four groups of animals with hepatic insufficiency (4, 6, 8, 10 weeks of intoxication) and two control groups (with or without phenobarbital/oil) were studied. After an i.v. bolus (1 mg/kg) of ICG, blood samples were collected for 120 min at definite time. For the intragastric route, ICG clearance and volume of distribution at steady-state were significantly decreased (p < 0.05), area under the curve and terminal half-life were significantly increased (p < 0.05). By contrast, no significant difference was observed after intraperitoneal administration, although the same pathological pattern was observed between the two routes of administration. This study proved the clinical importance of drug pharmacokinetics knowledge in liver disease and confirmed that ICG disposition is an adequate method for assessing hepatic function and dysfunction in animals with progressive liver disease.

Animals↗
PubMed1993

[Oxyntomodulin, a new hormonal marker of intestinal malabsorption syndromes].

Plasma oxyntomodulin-like immunoreactivity (OLI) concentrations were found to be significantly elevated in 6 patients with coeliac disease when compared with those observed in 38 healthy subjects. Furthermore, OLI hypersecretion is related to the degree of malabsorption. This marker could be used as a test for detection and follow-up of patients with malabsorptive disorders.

Adult↗
PubMed1993

Diurnal profile of oxyntomodulin-like immunoreactivity in duodenal ulcer patients.

Plasma concentrations of oxyntomodulin-like immunoreactivity, a group of intestinal peptides capable of mediating an enterogastrone signal, were measured during a 24-h period in 6 duodenal ulcer patients and compared with those of 16 age-matched controls. Each subject was submitted to 18 oxyntomodulin-like immunoreactivity determinations. Four standardized meals were given during the test. Furthermore, each patient was evaluated for peak acid output after pentagastrin stimulation. The values of the duodenal ulcer subjects were predominantly within normal acid secretion limits. Fasting levels, meal-induced variations, and nocturnal production of oxyntomodulin-like immunoreactivity were similar in the two groups. A negative correlation was observed between peak acid output and oxyntomodulin-like immunoreactivity evaluated either as nocturnal production or as maximum nyctohemeral concentration. We conclude that, taken as a whole, duodenal ulcer disease is not caused by a defect in oxyntomodulin-like immunoreactivity secretion. However, this study does not rule out the possibility of a selective deficiency of these peptides in some duodenal ulcer subgroups such as hypersecretory patients.

Adult↗
PubMed1992

Oxyntomodulin-like immunoreactivity: diurnal profile of a new potential enterogastrone.

The biological specificity of oxyntomodulin toward the gastric mucosa results from its C-terminal octapeptide. A RIA using a specific antibody raised against this region permitted quantification of the whole set of proglucagon-derived peptides that interact with the oxyntomodulin recognition systems, corresponding to the new concept of oxyntomodulin-like-immunoreactivity (OLI). The present report describes the physiological 24-h OLI profile in human plasma (eight men and eight women; mean age, 45 yr; range, 20-77 yr). Blood was withdrawn every hour from 0700-1900 h and every 2 h from 2100-0500 h. A meal-dependent profile was found for circulating OLI, with basal values (60 +/- 7 ng/L) at 0500 h and rises elicited by each food intake. The highest value (136 +/- 21 ng/L) was obtained at 2100 h. Plasma concentrations and diurnal variations of OLI were similar to those of the other intestinal peptides known to exert an endocrine function. The mean circulating OLI values increased with age, whereas no change was noticed according to sex. The inhibitory effect exerted by the peptides of the OLI family on gastric acid secretion, the meal dependence of their plasma concentrations, and the observed synchronism of their diurnal profile with that previously described for somatostatin make them candidates for an enterogastrone action.

Age Factors↗
PubMed1992

[Evaluation of the effects of molsidomine and propranolol-molsidomine combination on portal hemodynamics by pulsed Doppler ultrasound].

Molsidomine, a long acting vasodilator with antianginal properties, has been shown to decrease porto-hepatic pressure gradient in patients with cirrhosis. The present study aimed at assessing the effects of molsidomine, propranolol and of the association of these two drugs on portal vein blood flow as measured using Doppler and B-mode sonography. In 10 patients without liver disease (group 1), portal flow time average mean velocity (TAV) and portal vein blood flow (PVBF) were measured under basal conditions, 1 hour then 2 hours after ingestion of 4 mg of molsidomine. The same measurements were performed in 15 patients with cirrhosis (group 2) under basal conditions, 1 then 2 hours after double-blind administration of either molsidomine (10 patients) or placebo (5 patients). Fifteen further patients with cirrhosis (group 3) were studied after the double blind administration of 80 mg of propranolol and two hours later of 4 mg of molsidomine (10 patients) or placebo (5 patients); TAV and PVBF were measured under basal conditions, two hours after propranolol ingestion or placebo, then one and two hours after molsidomine or placebo ingestion. TAV and PVBF remained unchanged in patients treated with placebo. Molsidomine reduced TAV by 23.8 +/- 19.5% in group 1 (P < 0.01) and by 25.6 +/- 21.4% in group 2 (P < 0.01). In group 3, a 10% decrease was observed after propranolol (NS). When molsidomine was added, TAV was further decreased (-17.6 +/- 13.3% vs baseline, P < 0.01). PVBF remained unchanged in the three groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Oxyntomodulin and related peptides control somatostatin secretion in RIN T3 cells.

We studied the effects of oxyntomodulin (OXM), of its C-terminal (19-37) fragment (OXM (19-37)) and of glucagon (GLU) on somatostatin release, cyclic AMP accumulation and inositol phosphate turnover in somatostatin-secreting RIN T3 cells in culture. Rapid changes in cellular free Ca2+ were also measured using fura-2. Carbachol was used as a control test agent for the parameters involving the inositol phosphate/Ca2+ cascade. OXM, GLU and OXM (19-37) were all able to stimulate somatostatin release with relative ED50 of approx. 1, 22 and 45, respectively. OXM and GLU stimulated cyclic AMP levels with relative ED50 of approx. 1 and 30, respectively, whereas OXM (19-37) was totally ineffective on this parameter. In contrast to carbachol, none of the peptides significantly modified the inositol phosphate turnover or induced rapid changes in cellular free Ca2+. We conclude that the RIN T3 cells contain a receptor-cyclic AMP system similar to that found in gastric mucosa and that this system is linked to somatostatin release. Another receptor-second messenger mechanism linked to somatostatin release is triggered by the (19-37) fragment. This mechanism is not the inositol phosphate/Ca2+ cascade triggered in the same cells by cholinergic agents.

Animals↗
PubMed1990

[Hemorrhagic necrosis of the mesenteric lymph nodes in adult celiac disease. Physiopathologic interpretation of 1 case].

The authors report the case of a 35 year old woman dead of cachexia in the course of a refractory adult coeliac disease. The autopsy revealed multiple lymphadenopathies exclusively found in the small intestinal mesentery; all these lymph nodes were destroyed by an extensive haemorrhagic necrosis. There was neither lymphoma nor cavitation. These original findings are interpreted as the consequence of a localized intravascular coagulation, and probably a step towards cavitation or atrophy.

Adult↗