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Biomedical subjects

C Dupont

Publications and source records attributed to C Dupont.

At least 127 records · Page 7Linked to original sources
PubMed1998

The 13carbon urea breath test for the noninvasive detection of Helicobacter pylori in children: comparison with culture and determination of minimum analysis requirements.

BACKGROUND: The purpose of the study was to determine the accuracy of the labelled 13carbon urea breath test for the diagnosis of Helicobacter pylori in children and to simplify the 13carbon urea breath test in identifying the most discriminating sampling time. METHODS: H. pylori was searched for in 100 children aged 10.5+/-4.5 years by histology, bacteriological counts, and culture on antral biopsies together with serology and 13carbon urea breath test. Breath samples were obtained before ingestion (T0) of 75 mg urea-13C and every 10 minutes after until T60. 13CO2 excess ratio was measured by isotope ratio mass spectrometry, and values expressed as delta per mil over baseline enrichment (delta 13CO2). The arithmetic mean (Mdelta 13CO2) of T20 to T60 values was calculated and the test considered positive with Mdelta 3CO2 higher than Mdelta 13CO2 + 3 SD as determined in noninfected children. RESULTS: Mdelta 13CO2 of noninfected children as assessed by culture was 1.4+/-0.6 per mil, determining a positive cut-off value of 3.44 per mil. Mdelta 13CO2 was correlated in 11 children with biopsy bacteriological counts. Both culture and 13carbon urea breath test were positive in 38 of 100 children, without any discordance. Plotting 13carbon urea breath test results at each sampling time versus Mdelta 13CO2 showed weaker correlations at T20, T30, T50, and T60, than at T40. The two-sample method at T0 and T30, T40, T50, had high sensitivity and specificity. Single-sample analysis obtained at T40 gave a comparable sensitivity and a slightly reduced specificity. CONCLUSION: 13carbon urea breath test is sensitive and specific in children. Two samples collected at T0 and T40 provide the most discriminating procedure.

Adolescent↗
PubMed1998

Effect of metronidazole resistance on bacterial eradication of Helicobacter pylori in infected children.

A prospective study was performed with 23 Helicobacter pylori-infected children (mean age, 9.5 +/- 4.4 years) with clinical symptoms of gastritis and positive results of culture and histologic examination of gastric biopsy specimens to evaluate the influence of antibiotic resistance on eradication. Positive children were treated for 4 weeks with lansoprazole and for 2 weeks with either amoxicillin-metronidazole or spiramycin (a macrolide)-metronidazole. At endoscopy 1 month after the discontinuation of therapy, the eradication rate and improvement of histologically related gastritis were significantly dependent on the susceptibility or the resistance of the infecting organism to metronidazole (83 versus 17% and 88 versus 16.6%, respectively). Pretreatment determination of the susceptibility is appropriate in any anti-H, pylori regimen, including one with metronidazole.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1998

Possible protection by breast-feeding against severe esophageal and gastric lesions in the neonate. A case-control study.

The development of safe fiberoptic endoscopy in neonates led to the identification of the occurrence of severe esophageal and gastric lesions (EGL) in the first days of life. The cause of these early acute lesions, which are associated most of the time with severe clinical symptoms, remains unknown. 34 neonates with EGL were compared with controls born in the same maternity unit immediately after those enrolled in the EGL series. Clinical and obstetric data were not different in the 2 groups. Breast-feeding was less frequent (p < 0.01) and given later (p = 0.0001) in babies with EGL. This retrospective analysis yielded no indication relative to the causative phenomenon leading to such mucosal alterations. In contrast, it provides the first evidence of a possible protective role of breast-feeding.

Apgar Score↗
PubMed1998

Optimized non-radioactive protein truncation test for mutation analysis of the adenomatous polyposis coli (APC) gene.

Germline mutations in the adenomatous polyposis coli gene cause familial adenomatous polyposis, a colon cancer predisposition syndrome. More than 95% of the identified mutations result in the generation of stop codons or reading frame shifts and encode a truncated gene product, a mutation profile also found in other tumor predisposition genes such as the breast cancer or the hereditary non-polyposis coli. Therefore the protein truncation test is ideally suited for screening of mutations in these genes, starting from simple blood samples. Gene segments of interest are amplified from genomic DNA or mRNA, thereby incorporating a T7 promoter at the 5'-end. After in vitro transcription and translation of the PCR products, the resulting protein is analysed by gel electrophoresis. Truncated translation products indicate the presence of a stop mutation. We have developed a non-radioactive protein truncation test that uses a biotinylated Lys-t-RNA to label the translation products and allows a chemiluminescent detection instead of the standard radioactive method. This generic protein truncation test kit was then used to develop a parameter-specific protein truncation test for adenomatous polyposis coli. The adenomatous polyposis coli gene was divided in 5 overlapping segments, and primers were optimized to produce distinct bands with very low background in the protein truncation test. The assay was tested on 20 familial adenomatous polyposis patient samples, where 18 mutations were found, demonstrating the efficiency of this method.

Adenomatous Polyposis Coli↗
PubMed1997

The Streptomyces lividans family 12 endoglucanase: construction of the catalytic cre, expression, and X-ray structure at 1.75 A resolution.

Cellulases are the glycoside hydrolases responsible for the enzymatic breakdown of the structural plant polymer cellulose. Together with xylanases they counteract the lmitless accumulation of plant biomass in nature and are of considerable fundamental and biotechnological interest. Endoglucanase CelB from Streptomyces lividans performs hydrolysis of the beta-1,4-glycosidic bonds of cellulose, with net retention of anomeric configuration. The enzyme is a member of glycoside hydrolase family 12 [Henrissat, B., and Bairoch, A. (1996) Biochem. J. 316, 695-696], which had previously eluded detailed structural analysis. A truncated, but cataytically competent form of CelB, locking the flexible linker region and cellulose-binding domain, has been constructed and overexpressed in a S. lividans expression system. The three-dimensional X-ray structure of the resulting catalytic domain, CelB2, has been solved by conventional multiple isomorphous replacement methods and refined to an R factor of 0.187 at 1.75 A resolution. The overall fold of the enzyme shows a remarkable similarity to that of family 11 xylanases, as previously predicted by hydrophobic clustering analysis [Törrönen, A., Kubicek, C.P., and Henrissat, B. (1993) FEBS Lett. 321, 135-139]. The 23 kDa protein presents a jelly-roll topology, built up mainly by antiparallel beta-sheets arranged in a sandwich-like manner. A deep substrate-binding cleft runs across the surface, as has been observed in other endoglucanase structures, and is potentially able to accommodate up to five binding subsites. The likely catalytic nucleophile and Brønsted acid/base, residues Glu 120 and Glue 203, respectively, have their carboxylate groups separated by a distance of approximately 7.0 A and are located approximately 15 A from one end of the cleft, implying a -3 to +2 active site.

Binding Sites↗
PubMed1997

Non-endoscopic techniques for the evaluation of the pediatric airway.

In children with stridor, a detailed evaluation of the airway is often required to assess precisely its anatomical and functional status. Various methods of assessment have been developed and airway management may include, as well as rigid and flexible endoscopy, the use of imaging techniques such as plain X-rays, a barium oesophagogram, ultrasound, a CT scan, a magnetic resonance image (MRI) and an angiogram, as well as respiratory function tests including acoustic rhinometry and flow volume loops or even pH monitoring. This article aims to highlight the valuable information these alternative techniques can provide.

Airway Obstruction↗
PubMed1997

Characterization of two important histidine residues in the active site of xylanase A from Streptomyces lividans, a family 10 glycanase.

The active site of xylanase A (XlnA) from Streptomyces lividans contains three histidine residues, two of which (H81 and H207) are almost completely conserved in family 10 glycanases. The structural analysis of the enzyme shows that H81 and H207 are part of an important hydrogen bond network in the vicinity of the two catalytic residues (E128 and E236). In order to investigate the role of these two histidine residues for the structure/function of XlnA, three mutant enzymes were produced at each position, namely, H81R/S/Y and H207E/K/R. The specific activity of these mutant enzymes is reduced by more than 95%, revealing the importance of these two residues for the catalytic function of XlnA. The kinetic parameters of the three more active enzymes were determined, of which mutation H207K increased the K(M) 3-fold. The k(cat) of the mutant enzymes is reduced proportionally to the specific activity. Furthermore, the pKa values of the two catalytic residues are decreased in all six mutations, demonstrating a role for H81 and H207 in the hydrogen bond network responsible for maintaining the ionization state of the two catalytic residues. In most cases, the unfolding of mutated XlnA in guanidine hydrochloride (Gdn-HCl) showed that the concentration required to denature 50% of the XlnA decreased, thus demonstrating the importance of those two residues for the stability of the enzyme. Moreover, the m value [m = d(deltaG)/d[Gdn-HCl]] for the unfolding of XlnA in Gdn-HCl is increased for each of the six mutations, suggesting that the mutant proteins have less residual structure in the denatured state than does the wild-type enzyme.

Amino Acid Sequence↗
PubMed1997

In vivo antigenotoxic effects of dietary allyl sulfides in the rat.

The effects of dietary administration of diallyl sulfide (DAS), diallyl disulfide (DADS) and allyl mercaptan (AM) on the genotoxicity of different chemicals were studied in two experimental systems: (i) measurement of hepatic DNA single-strand breaks induced in rats by aflatoxin B1 (AFB1), N-nitrosodimethylamine (NDMA) or methylnitrosourea (MNU); (ii) mutagenicity of AFB1 or NDMA on Salmonella typhimurium TA100 using hepatic S9 from rats fed allyl sulfides as the activation system. All compounds strongly reduced hepatic DNA breaks induced by AFB1 and NDMA but did not modify the genotoxicity of MNU. In the Ames test, the mutagenicity of NDMA was strongly inhibited by hepatic S9 from rats fed either compound. The mutagenicity of AFB1 was also reduced but to a lesser extent. Such effects are likely related to the modulation of drug-metabolizing enzymes which play a key role in metabolic activation as well as detoxication of NDMA and AFB1.

Aflatoxin B1↗
PubMed1997

New alpha-L-arabinofuranosidase produced by Streptomyces lividans: cloning and DNA sequence of the abfB gene and characterization of the enzyme.

A fully secreted alpha-l-arabinofuranosidase was cloned from the homologous expression system of Streptomyces lividans. The gene, located upstream adjacent to the previously described xylanase A gene, was sequenced. It is divergently transcribed from the xlnA gene and the two genes are separated by an intercistronic region of 391nt which contains a palindromic AT-rich sequence. The deduced amino acid sequence of the protein shows that the enzyme contains a distinct catalytic domain which is linked to a specific xylan-binding domain by a linker region. The purified enzyme has a specific arabinofuranose-debranching activity on xylan from Gramineae, acts synergistically with the S. lividans xylanases and binds specifically to xylan. From small arabinoxylo-oligosides, it liberates arabinose and, after prolonged incubation, the purified enzyme exhibits some xylanolytic activity as well.

Amino Acid Sequence↗
PubMed1997

Mixed Candida glabrata and Candida albicans disseminated candidiasis in a heroin addict.

The case of a white-heroin addict who developed disseminated candidiasis following coinfection by Candida glabrata and Candida albicans is reported. Genomic random amplified polymorphic DNA typing suggested that the Candida glabrata blood isolates originated in the oral cavity of the patient. This case strengthens the evidence that Candida species other than Candida albicans can be involved in the pathogenesis of disseminated candidiasis in heroin addicts.

AIDS-Related Opportunistic Infections↗
PubMed1997

The relation between gastro-oesophageal reflux, sleeping-position and sudden infant death and its impact on positional therapy.

UNLABELLED: Many infants do regurgitate. The recommended therapeutic approach starts with postural and dietary measures, followed by antacids and prokinetics. However, the recent findings regarding the increased risk for sudden infant death (SID) in the prone sleeping position challenge the current recommendations. Management of regurgitation should in the first place aim at reducing parental anxiety. Postural treatment favouring the prone-elevated (30 degrees) position is no longer recommended as a first line treatment of regurgitation, despite its efficacy, because of the unexplained association of SID with the flat prone sleeping position. Favouring the prone elevated position would result in an increased parental anxiousness. CONCLUSION: Positional treatment can only be recommended in children beyond the age of SID risk, or as an adjuvant therapy in cases resistant to reassurance, thickeners and prokinetics and in whom other diagnostic possibilities (infection, etc.) are considered rejected.

Gastroesophageal Reflux↗
PubMed1997

A critical appraisal of current management practices for infant regurgitation--recommendations of a working party.

Regurgitation is a common manifestation in infants below the age of 1 year and a frequent reason of counselling of general practitioners and paediatricians. Current management starts with postural and dietary measures, followed by antacids and prokinetics. Recent issues such as an increased risk of sudden infant death in the prone sleeping position and persistent occult gastro-oesophageal reflux in a subset of infants receiving milk thickeners or thickened "anti-regurgitation formula" challenge the established approach. Therefore, the clinical practices for management of infant regurgitation have been critically evaluated with respect to their efficacy, safety and practical implications. The updated recommendations reached by the working party on the management of infant regurgitation contain five phases: (1 A) parental reassurance; (1 B) milk-thickening agents; (2) prokinetics; (3) positional therapy as an adjuvant therapy; (4 A) H2-blockers; (4 B) proton pump inhibitors; (5) surgery.

Antacids↗
PubMed1997

Human recombinant growth hormone increases small bowel lengthening after massive small bowel resection in piglets.

BACKGROUND/PURPOSE: Dramatic improvement in small bowel lengthening and in weight gain has been demonstrated in newborn rats treated with human growth hormone (GH) after massive small bowel resection. The aim of this study was to confirm these results in another animal model and to specify the part food intake plays in small bowel lengthening induced by GH. METHODS: Twenty-five piglets underwent laparotomy at day 28 of life. Intestinal length was measured under general anesthesia, and animals had an 80% resection of small bowel, leaving a similar length of jejunum and ileon. There were no perioperative deaths. One animal died 3 days after surgery. Animals were assigned to five groups: (1) S (n = 4): sham, mere laparotomy; (2) GH-S (n = 4): sham and GH treatment (0.1 IU/kg/d subcutaneously); (3) R (n = 7): intestinal resection; (4) GH-R (n = 6); and (5) GH-R AdL (n = 4): intestinal resection and GH treatment. S, GH-R, and GH-R AdL had a free diet; GH-S and GH-R were pair-fed with S and R, respectively. Animals were killed 28 days later. RESULTS: Weight gain was not different in the two nonresected groups (S, 144 +/- 6% of initial weight; GH-S, 150 +/- 3%) and was significantly higher than in the resected groups (R, 67 +/- 28%; GH-R, 74 +/- 16%; GH-R AdL, 55 +/- 16%; NS). GH did not enhance small bowel lengthening in the nonresected groups; S, 41.9 +/- 23% and GH-S, 36.9 +/- 9%, in sharp contrast with the resected groups; R, 28 +/- 9 cm versus GH-R, 96 +/- 39 cm (P = .0008) and versus GH-R AdL, 89 +/- 41 cm (P = .003). Compared with initial length, the increase was R, 16.2 +/- 5%; GH-R, 56.5 +/- 24%; GH-R AdL, 51 +/- 25%. Villus height and diameter, average number of mitosis per field, intestinal muscular layer, wall thickness, and crypt ratio were higher in resected groups than in unresected ones, with no difference observed between resected groups. CONCLUSIONS: GH improves the postoperative intestinal adaptation process after massive small bowel resection in newborn piglets in terms of small bowel lengthening. In contrast to rats, GH did not improve weight gain. In addition, no difference was observed whether animals were on a free or a controlled diet.

Adaptation, Physiological↗
PubMed1997

Allergy to extensively hydrolyzed cow milk proteins in infants: identification and treatment with an amino acid-based formula.

We report on 13 infants allergic to extensively hydrolyzed protein formulas (EHFs) who were first seen with chronic digestive symptoms. Feeding with an amino acid-based formula decreased symptoms and improved weight gain. A challenge with EHF produced positive results in all these infants. Allergy to EHF must be considered in patients who are allergic to cow milk and have persisting symptoms on an EHF diet.

Amino Acids↗