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T Vallot

Publications and source records attributed to T Vallot.

At least 55 records · Page 3Linked to original sources
PubMed1990

[pH gradient support and antacid action of gastroesophageal coating agents. In vitro pharmacologic study using a model of "the artificial stomach"].

The effects of gastroesophageal mucosal coating agents could be related to a) the decrease of aggressive contents of gastric juice and/or b) the presence of a pH gradient between intraluminal (IL) contents and mucosa. Antacid capacities of Gaviscon and Topaal, containing sodium alginate or alginic acid, respectively, were measured using the "artificial stomach" model. This model, reproducing two major gastric dynamic functions, secretion and gastric emptying, allows to evaluate the pH variations in the IL contents and at its surface, by a double pH metric recording. Experiments were performed when drugs to be tested were added either to 100 ml of human gastric juice (100 mmol/l or 88 mmol/l with biliary reflux) or to 100 ml of 0.1 N HCl, without and with 1 percent meat extract. Simulated secretion was represented by a 3 ml/min flux of either 0.1 N HCl or gastric juice and "gastric emptying" fluxes varied from 1.5, 3.0 to 4.5 ml/min. When 0.1 N HCl solution was used, the pH levels at the surface of IL contents were close to pH 3.0 when intragastric pH reached pH 1.0 independently of "gastric" emptying flux variations. In the presence of proteins or biliary reflux material, these pH levels were higher, close to pH 4.5 and persisted for a longer time. Antacid activity was calculated as the resistance to acidification of the IL contents, as the amount of H+ ions consumed after addition of antacid to recover initial pH, i.e. 37 and 22 mmol in human gastric juice, between 37 and 17.5 mmol in 0.1 N HCl for Gaviscon and Topaal, according to emptying fluxes.(ABSTRACT TRUNCATED AT 250 WORDS)

Alginates↗
PubMed1990

New approach for the in vitro evaluation of antacids.

Evidence is given that the in vitro evaluation of antacids has been incomplete, not regarding physiopathological conditions. As a consequence arbitrary antacid potency classifications were introduced and in clinical practice high dosages of antacid drugs were prescribed. The main reason is that the in vitro evaluation procedures used did not take into account the actual conditions of gastric acid secretion. The proposed methods allow to assess antacid activity under conditions similar to those during gastric secretion. "Pharmacologically", the capacity of binding H+ ions in acid milieu can be quantified and the antacid mechanism can be characterized. "Therapeutical efficacy" might be analysed under acid conditions taking into account gastric intraluminal flux variations by using the "artificial stomach" model. This procedure also allows to evaluate the influence of gastric protein content on antacid activity and to simulate the actual gastric conditions by using human gastric juice as gastric content and as simulated "secretion". The antacid-induced resistance to acidification largely corresponds to the therapeutical antacid activity. Data obtained with aluminum containing antacids are presented.

Antacids↗
PubMed1989

Intestinal infections in patients with acquired immunodeficiency syndrome. A prospective study in 132 patients.

We studied prospectively 132 patients with acquired immunodeficiency syndrome to define the spectrum of enteric pathogens during this disease, with special reference to the correlation between the lesions, the infections, and the symptoms. Forty-four percent of the patients harbored at least one enteric pathogen: the most frequently recovered were Cryptosporidium (28), cytomegalovirus (16), Entamoeba histolytica (13), Giardia lamblia (9), and Mycobacterium avium intracellulare (7). Patients harboring pathogens were more likely to be diarrheics (69%) than patients without a pathogen (38%; P = 0.01) and more likely to have endoscopic lesions (29%) than patients without a pathogen (4%; P less than 0.001). The most common pathogen associated with diarrhea was Cryptosporidium. Cytomegalovirus, Entamoeba histolytica, and Salmonella typhimurium were each significantly associated with endoscopic lesions. Patients with cytomegalovirus infection tended to have a greater incidence of ulcer than patients without cytomegalovirus infection. Stool analysis diagnosed 61% of the infections, while endoscopy diagnosed 44%. Seven percent were recognized by stool analysis and endoscopy. When considering the 24 patients in whom accurate diagnosis warranted endoscopic biopsies, stool examination alone would have given an incomplete diagnosis in 14 patients (due to the presence of polyinfection). The frequency of inaccurate diagnosis of infection by stool determination alone, plus the development of new antiviral agents that suppress cytomegalovirus, may favor the earlier application of endoscopic evaluation in these patients.

Acquired Immunodeficiency Syndrome↗
PubMed1989

[Tri-annual rhythm of basal acid secretion and secretion stimulated by pentagastrin in duodenal ulcer].

Duodenal ulcer is a recurrent disease with seasonal periodicity for pain and complications such as hemorrhage and perforation. Ulcer craters or symptoms seem to occur preferentially in early spring and autumn. Since acid secretion is one of the pathogenetic factors of the disease, we analyzed retrospectively basal and maximal (pentagastrin) acid secretion data obtained in 341 consecutive patients according to the month in which they were obtained. The patients were classified according to the activity of their ulcer (active, non active) and to the level of the peak acid secretion (hypersecretors, normosecretors). Basal acid concentration and output, and peak acid output were, both overall and month by month, higher in patients with active duodenal ulcer disease than in those who were non active, and in hypersecretors than in normosecretors. For all 341 patients as well as for normosecretors and non active ulcer patients, a triannual rhythm was detected for stimulated acid concentration and peak acid output. The highest values were noted in February, June, and October (period: 4 months). The amplitude of these rhythms was 3 to 4 percent, with differences between highest and lowest values of 30.4 mmol/l for concentration and 17.1 mmol/h for peak acid output. These rhythms for acid secretion during the year may contribute to the periodicity of duodenal ulcer events and should be analyzed in association with other factors which could be implied in ulcerogenesis. Moreover, this seasonal periodicity of acid secretion in duodenal ulcer should be taken into account in all therapeutic trials in which acid secretion is analyzed.

Adolescent↗
PubMed1988

[The effect of ranitidine on gastric pH measured by continuous monitoring over 24 hours in healthy subjects. Comparison of 2 methods of administration: 150 mg morning and night, vs 300 mg in a single dose at night].

The gastric pH of 8 healthy subjects was determined, in a continuous fashion, during three different 24 hour periods corresponding to the 3 following treatments: Placebo, ranitidine 150 mg twice per day, and ranitidine 300 mg in the evening. During each period, the feeding conditions were normal and standardized. The results are expressed in terms of the number of hours under a threshold pH value. In comparison with the placebo, ranitidine, regardless of its mode of administration, results in a significant decrease of the mean number of hours under pH 1.5, 2 and 3 during 24 hours; no significant difference was demonstrated between the two modes of administration in 24 hours. During the 12 night-hours, a single dose of 300 mg of ranitidine was more effective to ranitidine taken in 2 doses for pH thresholds of 2 and 3, while during the 12 day-hours, no difference was demonstrated for pH thresholds of 1.5, 2 and 3. The analysis of the mean pH graphs in relation to time, suggests that a single 300 mg dose is more effective than the same dose divided into 2 doses during the day. These results tally with the variations of ranitidine plasma levels in 24 hours. These results justify, from a pharmacological standpoint, the prescription of a single dose of ranitidine, in the evening.

Adult↗
PubMed1983

Evaluation of antisecretory drug therapy of Zollinger-Ellison syndrome (ZES) using 24-hour pH monitoring.

Clinical and endoscopic findings were compared with 24-hr pH profiles in 8 patients with Zollinger-Ellison syndrome (ZES), who were being treated, during consecutive periods, with doses of cimetidine or ranitidine. There was a positive correlation between the effect on gastric pH and the outcome of treatment, with ranitidine proving to be more effective. The reduction of gastric acidity was correlated with ranitidine plasma levels. In the medical management of ZES patients, the 24-hr pH profile appears to be a measurement which is of value in the choice of appropriate drug regimes and which promises to increase our understanding of treatment failure.

Adult↗