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Biomedical subjects

C Dupont

Publications and source records attributed to C Dupont.

At least 19 recordsLinked to original sources
PubMed1992

[Relationship between gastroesophageal reflux and severe malaise in infants].

The relationship between gastroesophageal reflux (GER) and sudden infant death syndrome (SIDS) has been widely investigated. Reflux-induced apnoea is triggered through a vagal mechanism. During acute phases of sleep, the different means of protection of the upper respiratory tract are blunted, awakening reactions are cancelled or delayed and hypoxemia occurs rapidly. GER could play a leading part in SIDS occurring during this acute phase of sleep. Numerous studies are needed to further dismantle the link between SIDS and GER. In children with severe malaise, a systematic search for GER is mandatory.

Death, Sudden↗
PubMed1992

Effect of diosmectite on intestinal permeability changes in acute diarrhea: a double-blind placebo-controlled trial.

The effect of diosmectite on intestinal permeability changes in acute diarrhea was measured during a double-blind placebo-controlled trial carried out in 59 Gabonese children aged 5-35 months. Intestinal permeability tests (IPTs), measuring the urinary elimination of orally administered lactulose and mannitol at a dosage of 1 g/10 kg each, were performed during the morning following admission and repeated 2 days later after treatment by diosmectite or placebo. During the first IPT, urine volume and lactulose and mannitol urinary recoveries were comparable in the diosmectite and in the placebo groups: 50 vs. 35.5 ml (median; p = 0.21), 1.01 vs. 1.27% (p = 0.35), and 2.20 vs. 2.87% (p = 0.12). As a result, the lactulose/mannitol (L/M) ratio was similar in the two groups: 44.44 vs. 35.33% (p = 0.98). During the second IPT, the urinary lactulose recovery decreased similarly in both groups (-0.18 vs. -0.29%; p = 0.76), whereas the urinary mannitol recovery exhibited opposite variations, the increase in the diosmectite group (+ 1.43%) contrasting significantly with the decrease in the placebo group (-0.47%; p = 0.01). When comparing the first and the second IPT, the decrease of the L/M ratio was significant in the diosmectite group (44.44 vs. 28.32%; p = 0.02) and not in the placebo group (35.33 vs. 48.23%; p = 0.91). During gastroenteritis, diosmectite appears to enhance absorption of mannitol, a marker of intestinal absorptive area.

Acute Disease↗
PubMed1992

O-acetylated peptidoglycan: its occurrence, pathobiological significance, and biosynthesis.

Bacterial cell walls and their structural units, particularly peptidoglycan, induce a vast variety of biological effects in host organisms. The pathobiological effects of peptidoglycan are greatly enhanced by various modifications and substitutions to its basic composition and structure. One such modification is the presence of acetyl moieties at the C-6 hydroxyl group of N-acetylmuramyl residues, and to date, 11 species of eubacteria, including some important human pathogens, such as Neisseria gonorrhoeae, Proteus mirabilis, and Staphylococcus aureus, are known to possess O-acetylated peptidoglycan. This review addresses the influence of O-acetylation of peptidoglycan on its resistance to degradation both in vitro and in vivo, the clinical importance of the modification, and the currently held views on the pathway for its biosynthesis.

Acetates↗
PubMed1992

Influence of intestinal parasitism on lactose absorption in well-nourished African children.

Hydrogen breath tests were performed in Gabon (Central Africa) after a loading dose of lactose in 67 well-nourished African children (50 with intestinal parasites and 17 unparasitized) and in 18 unparasitized young adults. All had normal nutritional status, and none had diarrhea or digestive symptoms. Parasites that were found included Ascaris lumbricoides in 76% of the parasitized children, Trichuris trichiura in 58%, Giardia in 24%, Entamoeba histolytica in 20%, Schistosoma intercalatum in 16%, and Necator Americanus in 14%. A similar proportion of parasitized (64%) or unparasitized (62.8%) subjects were lactose malabsorbers. Giardia infection was associated with a higher, but not significantly different, proportion of lactose intolerance (10 of 12, 83.3%). The presence of infection with A. lumbricoides or T. trichiura did not increase the percentage of lactose malabsorption. These data indicate that a decrease of lactase activity in well-nourished African children is not related to the presence or the importance of Ascaris or other intestinal parasites if the nutritional status is normal.

Animals↗
PubMed1992

[Multicenter study of sodium alginate in the treatment of regurgitation in infants].

An open multicenter study was performed to assess the efficacy and safety of alginic acid in two different dosages in 76 pediatric patients with gastroesophageal reflux confirmed by pH monitoring. Among the 69 patients in whom endoscopy was carried out before treatment, 18 had erythematous esophagitis and 5 had erosive esophagitis. Irrespective of the dosage used, the frequency of regurgitation and vomiting decreased significantly (p < 0.00001 and p = 0.01, respectively). Clinical and biochemical tolerance were outstanding and no adverse effects were recorded. On the basis of these data, the recommended dosage is 1 to 2 ml/kg/day in divided doses after meals.

Alginates↗
PubMed1992

[Diagnosis of food allergy in children].

In infants, food allergies are usually manifested by digestive symptoms and the most commonly involved antigens are cow's milk proteins. Although the full range of clinical manifestations of cow's milk protein sensitivity may occur as soon as birth, enteropathy is the most common pattern. As the infant grows, cow's milk antigens lose their predominance as the causative agents of adverse reactions to foods. All foods may be involved, and consequently diagnostic evaluation is more difficult. The gastrointestinal tract is no longer the preferred target organ and symptoms of food allergy may be systemic, cutaneous or, in a smaller number of cases, respiratory. History taking is the first step of the diagnostic process and provides very valuable data. Skin tests and in vitro detection of specific IgE antibodies are then performed. Results of the skin tests may help select the most appropriate in vitro tests. Diagnosis is always established by diet modifications using diets free of the suspected offending food, followed by challenge tests. Intestinal permeability tests provide a noninvasive means for demonstrating intestinal reactivity.

Biopsy↗
PubMed1992

[Value of the intestinal permeability test with lactulose-mannitol for screening and monitoring of celiac disease in children].

An intestinal permeability test (IPT) analysing the mannitol (M) and lactulose (L) clearances and the L/M ratios was performed in 15 children followed for celiac disease, before the onset of exclusion diet, during the gluten-free diet and after the reintroduction of gluten. The results showed a significant increase of the L/M ratios under normal diet, with respect to a control population. This increase was related to an increased L urinary excretion and to a decrease in M excretion. During gluten-free diet a normalization of the L/M ratios was observed. Reintroducing gluten altered the L/M ratios by increasing the L intestinal permeability and decreasing the M intestinal permeability. This study shows the value of the non invasive L/M IPT for the screening and monitoring of celiac disease in children.

Celiac Disease↗
PubMed1991

Dependence of lysozyme-catalysed solubilization of Proteus mirabilis peptidoglycan on the extent of O-acetylation.

The degree of peptidoglycan O-acetylation in 14 strains of Proteus mirabilis has been accurately determined by a procedure which employs the quantitation of mild-base-released acetic acid by HPLC, and the estimation of peptidoglycan concentration by cation-exchange amino acid analysis. The beta-D-N,6-O-diacetylmuramyl content of all isolated and purified peptidoglycans was ranged 20-52.8%, relative to the total muramic acid concentration. Each of the O-acetylated peptidoglycans was found to be resistant to solubilization by both human and hen egg-white lysozymes and for hen egg-white lysozyme, the extent of this resistance was dependent upon the degree of O-acetylation. The steady-state parameters, Km and V, for the hen-egg-white-lysozyme-catalysed solubilization of various peptidoglycan preparations were determined at pH 6.61 and 25 degrees C. Values of Km for the different peptidoglycan samples were found to increase with increasing O-acetylation, whereas with V no such relationship appeared to exist. An increase in the overall change in the standard Gibbs free energy of activation [delta(delta G#)], a consequence of increasing O-acetylation, was observed, and is shown to result from the weaker affinity of the enzyme for the modified substrates.

Acetylation↗
PubMed1991

Evidence for N----O acetyl migration as the mechanism for O acetylation of peptidoglycan in Proteus mirabilis.

O-acetylated peptidoglycan was purified from Proteus mirabilis grown in the presence of specifically radiolabelled glucosamine derivatives, and the migration of the radiolabel was monitored. Mild-base hydrolysis of the isolated peptidoglycan (to release ester-linked acetate) from cells grown in the presence of 40 microM [acetyl-3H]N-acetyl-D-glucosamine resulted in the release of [3H]acetate, as detected by high-pressure liquid chromatography. The inclusion of either acetate, pyruvate, or acetyl phosphate, each at 1 mM final concentration, did not result in a diminution of mild-base-released [3H]acetate levels. No such release of [3H]acetate was observed with peptidoglycan isolated from either Escherichia coli incubated with the same radiolabel or P. mirabilis grown with [1,6-3H]N-acetyl-D-glucosamine or D-[1-14C]glucosamine. These observations support a hypothesis that O acetylation occurs by N----O acetyl transfer within the sacculus. A decrease in [3H]acetate release by mild-base hydrolysis was observed with the peptidoglycan of P. mirabilis cultures incubated in the presence of antagonists of peptidoglycan biosynthesis, penicillin G and D-cycloserine. The absence of free-amino sugars in the peptidoglycan of P. mirabilis but the detection of glucosamine in spent culture broths implies that N----O transacetylation is intimately associated with peptidoglycan turnover.

Acetates↗
PubMed1991

In vitro synthesis and O acetylation of peptidoglycan by permeabilized cells of Proteus mirabilis.

The synthesis and O acetylation in vitro of peptidoglycan by Proteus mirabilis was studied in microorganisms made permeable to specifically radiolabelled nucleotide precursors by treatment with either diethyl ether or toluene. Optimum synthesis occurred with cells permeabilized by 1% (vol/vol) toluene in 30 mM MgCl2 in in vitro experiments with 50 mM Tris-HCl buffer (pH 6.80). Acetate recovered by mild base hydrolysis from sodium dodecyl sulfate-insoluble peptidoglycan synthesized in the presence of UDP-[acetyl-1-14C]N-acetyl-D-glucosamine was found to be radioactive. Radioactivity was not retained by peptidoglycan synthesized when UDP-[acetyl-1-14C]N-acetyl-D-glucosamine was replaced with both unlabelled nucleotide and either [acetyl-3H]N-acetyl-D-glucosamine or [glucosamine-1,6-3H]N-acetyl-D-glucosamine. In addition, no radioactive acetate was detected in the mild base hydrolysates of peptidoglycan synthesized in vitro with UDP-[glucosamine-6-3H]N-acetyl-D-glucosamine as the radiolabel. Chasing UDP-[acetyl-1-14C]N-acetyl-D-glucosamine with unlabelled material served to increase the yield of O-linked [14C]acetate, whereas penicillin G blocked both peptidoglycan synthesis and [14C]acetate transfer. These results support the hypothesis that the base-labile O-linked acetate is derived directly from N-acetylglucosamine incorporated into insoluble peptidoglycan via N----O transacetylation and not from the catabolism of the supplemented peptidoglycan precursors followed by subsequent reactivation of acetate.

Acetylation↗
PubMed1991

Importance of blood flow to the local distribution of drugs after percutaneous absorption in the bipediculated dorsal flap of the hairless rat.

In order to study the importance of cutaneous blood flow variations to percutaneous drug absorption and local distribution, a bipediculated dorsal flap was created in the hairless rat. This model allowed us to compare the percutaneous drug absorption on both sides of the flap, one with normal blood flow and the other with a reproducible blood flow decrease (60%) obtained by ligation of one pedicle. 14C-labelled compounds, progesterone (lipophilic), caffeine (amphiphilic) and urea (hydrophilic) were applied in ethanolic solution during 4 h on the two sides of the flap. When the cutaneous blood flow was lowered, the skin radioactivity increased greatly for caffeine (76% in superficial dermis, 67% in deep dermis), less for progesterone (37% in superficial dermis, 30% in deep dermis). For urea, no significant difference was observed between the two sides of the flap. Nevertheless, when the absorption of urea was promoted by application on stripped skin, radioactivity was greatly increased on the ligated side of the flap (240% in superficial dermis, 423% in deep dermis). Our results showed that a hydrophilic compound poorly absorbed (urea) was insensitive to cutaneous blood flow modifications whereas compounds readily absorbed (caffeine, amphiphilic; urea on stripped skin) or slightly absorbed (progesterone, lipophilic) exhibited local concentration phenomena in relation to cutaneous blood flow lowering.

Animals↗