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Biomedical subjects

C Dupont

Publications and source records attributed to C Dupont.

At least 109 records · Page 6Linked to original sources
PubMed1999

Fecal tumor necrosis factor alpha, eosinophil cationic protein and IgE levels in infants with cow's milk allergy and gastrointestinal manifestations.

Infants with atopic eczema exhibit a specific fecal protein pattern after oral challenge with cow's milk, characterized by an increase in both eosinophil cationic protein (ECP) and tumor necrosis factor (TNF)alpha. The aim of our study was to determine the pattern of these proteins in allergic infants with intestinal manifestations. TNFalpha, ECP and immunoglobulin E (IgE) were measured in stools from 13 infants with intestinal symptoms and 10 healthy infants. The allergic infants underwent two stool collections, one before a cow's milk challenge and the other after the challenge, either at the onset of clinical manifestations (n=6) or 15 days after the challenge if no clinical manifestations occurred (n=7). Baseline TNFalpha, ECP and IgE levels were low in all infants. The concentration of TNFalpha increased after the challenge in infants positive to challenge (p<0.05) but not in those negative to challenge. ECP and IgE levels remained low after the challenge in all the allergic infants. These data confirm that fecal TNFalpha and ECP levels indicate various reaction types of food allergy and that different immunologic disturbances lead to atopic eczema or intestinal symptoms during food allergy. Fecal protein pattern can thus be a useful tool in diagnosing food allergy in infants with intestinal manifestations.

Blood Proteins↗
PubMed1999

Mutations in the cationic trypsinogen gene and evidence for genetic heterogeneity in hereditary pancreatitis.

Hereditary pancreatitis (HP) is a rare inherited disorder, characterised by recurrent episodes of pancreatitis often beginning in early childhood. The mode of inheritance suggests an autosomal dominant trait with incomplete penetrance. The gene, or at least one of the genes, responsible for hereditary pancreatitis has been mapped to the long arm of chromosome 7 and a missense mutation, an arginine to histidine substitution at residue 117 in the trypsinogen cationic gene (try4) has been shown to segregate with the HP phenotype. The aim of this work was to investigate the molecular basis of hereditary pancreatitis. This study was performed on 14 HP families. The five exons of the trypsinogen cationic gene were studied using a specific gene amplification assay combined with denaturing gradient gel electrophoresis (DGGE). The present paper describes three novel mutations, namely K23R and N29I and a deletion -28delTCC in the promoter region. We also found a polymorphism in exon 4, D162D. In eight of these families we found a mutation which segregates with the disease. A segregation analysis using microsatellite markers carried out on the other families suggests genetic heterogeneity in at least one of them. Our findings confirm the implication of the cationic trypsinogen gene in HP and highlight allelic diversity associated with this phenotype. We also show that the pattern of inheritance of HP is probably complex and that other genes may be involved in this genetic disease.

Cations↗
PubMed1999

[Chronic laryngitis in children: the role of gastroesophageal reflux].

UNLABELLED: Gastro-oesophageal reflux (GOR) is associated with a number of inflammatory ENT disorders in the adult and is correlated with recurrent croup in the child. AIM: To estimate the frequency of GOR in a population of children consulting for chronic laryngotracheal symptoms. METHOD: The study included 17 children, aged between 2 and 14 years (mean: 7 years) all of whom suffered from dysphonia or a chronic cough. After a clinical ENT examination, each child had a fibreoptic laryngoscopy and a long duration pH-study lasting between 18 and 24 hours. RESULTS: Pathological GOR was discovered in 10 children, i.e. 59%. Overall the number of refluxes per study varied from 6 to 816 (mean 156). The vast majority of these refluxes occurred when the child was awake. CONCLUSION: In our series of children with chronic laryngotracheal disorders, at least 59% were shown to suffer from pathological GOR.

Adolescent↗
PubMed1999

[Intrication of smooth and striated muscle during the development of the ano-rectal sphincter].

The development of the foetal anorectal continence is related to the appearance of the anatomical components of the sphincter. The present study has been carried out in order to analyse the development of the smooth and striated components of the anorectal sphincter, in a series of 7 embryo and foetuses aged from 10 to 40 weeks of pregnancy. Our results indicate that the external sphincter, the puborectalis muscle and the internal sphincter are present before 24 weeks, although they obviously play variable roles in the establishment of the foetal continence. The internal sphincter becomes quantitatively important after 14 weeks, and is likely to be responsible for the establishment of the initial continence. The growth of the striated components during the foetal period corresponds to the maturation of the innervation and of the voluntary mechanisms controlling continence. Intrication of smooth and striated muscle components in the external sphincter starts after the end of the embryonic period. All the anatomical components of the anorectal sphincter are present at birth.

Anal Canal↗
PubMed1999

Effect of carbon source, growth and temperature on the expression of the sec genes of Streptomyces lividans 1326

The mRNA level in sec genes of Streptomyces lividans was studied as a function of growth temperature, glucose effect, and growth using two different carbon sources. Glucose and xylan, a complex hemicellulose, were used as carbon sources for the growth of S. lividans. For both substrates, the mRNA levels of secA, secD, secE, secF, and secY genes were almost constant during the early and log phases, but showed a marked decrease at the beginning of the stationary phase followed by a full recovery of mRNA level in the late stationary phase. This indicates that the sec genes are actively transcribed during the differentiation process. The mRNA level in xylan was generally from 1.5- to 2-fold that in glucose. At growth temperatures of 28 degrees C, 34 degrees C, or 40 degrees C, there was no significant difference in the sec gene mRNA levels.

Journal Article↗
PubMed1998

Identification of Glu-120 as the catalytic nucleophile in Streptomyces lividans endoglucanase celB.

Streptomyces lividans CelB is a family-12 endoglucanase that hydrolyses cellulose with retention of anomeric configuration. A recent X-ray structure of the catalytic domain at 1.75 A resolution has led to the preliminary assignment of Glu-120 and Glu-203 as the catalytic nucleophile and general acid-base respectively [Sulzenbacher, Shareck, Morosoli, Dupont and Davies (1997) Biochemistry 36, 16032-16039]. The present study confirms the identity of the nucleophile by trapping the glycosyl-enzyme intermediate with the mechanism-based inactivator 2', 4'-dinitrophenyl 2-deoxy-2-fluoro-beta-D-cellobioside (2FDNPC). The kinetics of inactivation proceeded in a saturable fashion, yielding the parameters kinact=0.29+/-0.02 min-1 and Kinact=0.72+/-0.08 mM. Uncompetitive inhibition was observed at high concentrations of 2FDNPC (Ki=9+/-1 mM), a behaviour that was also observed with the substrate 2',4'-dinitrophenyl beta-D-cellobioside (kcat=40+/-1 s-1, Km=0.35+/-0.03 mM, Ki=24+/-4 mM). Protection against inactivation was afforded by the competitive inhibitor cellobiose. The electrospray ionization (ESI) mass spectrum of the intact labelled CelB indicated that the inactivator had labelled the enzyme stoichiometrically. Reactivation of the trapped intermediate occurred spontaneously (kH2O=0.0022 min-1) or via transglycosylation, with cellobiose acting as an acceptor ligand (kreact=0.024 min-1, Kreact=54 mM). Digestion of the labelled enzyme by pepsin followed by LC-ESI-tandem MS (MS-MS) operating in neutral loss mode identified a labelled, singly charged peptide of m/z 947.5 Da. Isolation of this peptide by HPLC and subsequent collision-induced fragmentation by ESI-MS-MS produced a daughter-ion spectrum that corresponded to a sequence (QTEIM) containing Glu-120. The nucleophile Glu-120 and the putative acid-base catalyst Glu-203 are conserved in all known family-12 sequences.

Amino Acid Sequence↗
PubMed1998

Magnesium deficiency-dependent audiogenic seizures (MDDASs) in adult mice: a nutritional model for discriminatory screening of anticonvulsant drugs and original assessment of neuroprotection properties.

A great many animal models for audiogenic seizures have been described. The extent to which these models may provide insight into neuroscience fields such as abnormal locomotor behavior (wild running), seizures and anticonvulsants, and neuroinsults and neuroprotectors is examined here by our study of magnesium deficiency-dependent audiogenic seizures (MDDASs) in adult mice. MDDASs were induced in all of the eight tested adult murine strains and are presented as a sequence of four successive components (latency, wild running, convulsion, and recovery phase periods). Compared with several classic seizure tests, the nutritional MDDAS model responded to low doses of prototype antiepileptic drugs (AEDs), including phenytoin (PHT), carbamazepine (CBZ), phenobarbital (PB), valproic acid (VPA), ethosuximide (ESM), and diazepam (DZP). Modulation by AEDs of the four components of MDDAS indicated that this seizure test was discriminatory, distinguishing between phenytoinergic (PHT, CBZ), GABAergic (PB, VPA, DZP), and ethosuximide (ESM) compounds. Suitability of the MDDAS test for evaluation of neuroprotective compounds was also examined: it showed partial (melatonin) and complete (WEB2170, an anti-PAF agent) reduction of recovery phase by non-anticonvulsant doses of test compounds. These neuroprotective responses were compared with neuroprotective potentials determined in a model of neonatal cerebral injury induced by focal injection of ibotenate (a glutamate analog). WEB2170 and melatonin reduced the size of lesions in white matter, but only WEB2170 protected cortical plate against ibotenate-induced lesions. In addition to the original neuroprotective behavior of WEB2170, studies on the neuroprotectors also supported GABAergic anticonvulsant activity of melatonin in the MDDAS test.

Acoustic Stimulation↗
PubMed1998

Substrate-binding domains of glycanases from Streptomyces lividans: characterization of a new family of xylan-binding domains.

The substrate-binding domains of six glycanases from Streptomyces lividans were investigated to determine their specificity towards cellulose and xylan. Based upon amino acid sequence similarities, four of the six domains could be assigned to existing cellulose-binding domain families. However, the binding domains of xylanase A and arabinofuranosidase B could not be classified in any of the known families and should therefore be classified as members of a new family. Evidence is also presented that this new family is one of true xylan-binding domains.

Amino Acid Sequence↗
PubMed1998

[Gastroesophageal reflux in children].

Gastro-oesophageal reflux is a common disease in childhood, indicating either a variation from normal in the first months of life or a genuine disease in older infants or children. Digestive symptoms dominate in the young infant whereas respiratory ones should not be overlooked when the child grows. Diagnosis relies on history and clinical examination. (Esophageal pH-metry and/or upper endoscopy may be required. Most of the time, medical management appears sufficient.

Child, Preschool↗
PubMed1998

Prophylactic tranexamic acid and epsilon-aminocaproic acid for primary myocardial revascularization.

BACKGROUND: The efficacy of prophylactic epsilon-aminocaproic acid and tranexamic acid to reduce transfusions after primary myocardial revascularization was evaluated in a teaching hospital context. METHODS: Patients (n = 134) received either epsilon-aminocaproic acid (15-g bolus + infusion of 1 g/h), high-dose tranexamic acid (10-g bolus + placebo infusion), or normal saline solution in a double-blind fashion. Anticoagulation and conduct of cardiopulmonary bypass were standardized. RESULTS: Tranexamic acid and epsilon-aminocaproic acid produced a significant reduction in postoperative blood loss compared with placebo (median loss, 438 mL, 538 mL, and 700 mL, respectively). Transfusion of red cells was similar in all three groups. Nonetheless, the percentage of patients receiving hemostatic blood products was significantly decreased in the epsilon-aminocaproic acid group compared with the placebo group (20% versus 43%; p = 0.03). Both tranexamic acid and epsilon-aminocaproic acid significantly decreased total exposure to allogeneic blood products compared with placebo (p = 0.01 and p = 0.05, respectively), and this reduction was clinically important (median exposure, 2, 2, and 7.5 units, respectively). Fibrinolysis was inhibited significantly in both treatment groups. CONCLUSIONS: We conclude that either high-dose tranexamic acid or epsilon-aminocaproic acid effectively reduces transfusions in patients undergoing primary, elective myocardial revascularization.

Aminocaproic Acid↗
PubMed1998

[Prevalence of Helicobacter pylori infection in children according to their age. A retrospective study].

UNLABELLED: The aim of this study was to evaluate the prevalence of H pylori infection in a Parisian children population. PATIENTS AND METHODS: During a 3-year period, H pylori infection was investigated in 623 children admitted to our hospital. Children were enrolled into two groups; either a symptomatic children group with clinical gastritis manifestations as infant colics or recurrent abdominal pain for more than 3 months in whom H pylori infection was suspected, or a control children group with growth retardation of more than -2 standard deviation (SD). Ethnic origin for all enrolled children was identified. A written parental consent was obtained for all children. H pylori infection was identified by enzyme-linked immunosorbent assay (ELISA) (Cobas Core Roche, IgG, 2nd generation, Roche, France). RESULTS: H pylori infection was identified in 99 children out of 623 (15.8%). There was no difference between the two groups of children for age, sex, ethnic origin and prevalence of H pylori infection. The prevalence of H pylori infection was widely dependent on age and rose regularly with an annual acquisition rate of 2.1%. The prevalence of this infection varied from 1.8% during the first year of life to 30% in 15-year-old children. CONCLUSION: The latter prevalence is quite similar to that found in adults, suggesting that infection might occur in early life.

Adolescent↗
PubMed1998

[The 13C-urea breath test in Helicobacter pylori gastric infection in children].

Helicobacter pylori gastric infection in children is a public health problem. Classical diagnostic tools such as endoscopy are excessively invasive in the usual clinical context. Serology at this age has multiple drawbacks. The urea-13C breath test seems today the most appropriate alternative method. The principle of the test relies upon the indirect detection of H pylori through its high urease activity. The test uses a stable (ie, non radioactive) isotope, which allows its repeated use. The main indications are the detection and the follow-up of H pylori infection.

Adult↗
PubMed1998

Intracellular neutralization of HIV transcytosis across tight epithelial barriers by anti-HIV envelope protein dIgA or IgM.

Human immunodeficiency virus, generated during contact between HIV-infected cells and the apical surface of an epithelial cell, can cross a tight epithelial barrier by transcytosis. We show that transcytosis of primary HIV isolates is blocked by dimeric IgA or IgM against HIV envelope proteins. Neutralization occurs intracellularly within the apical recycling endosome, and immune complexes are specifically recycled to the mucosal surface. One epitope involved in neutralization is a conserved sequence of the gp41 HIV envelope protein subunit. Finally, transcytosis also occurs across functional human mucosal tissue in a process inhibited by a serosal internalization of IgM against the HIV envelope protein. These results suggest that induction of mucosal immunity to HIV envelope proteins may impair the transcytotic route of HIV mucosal transmission.

Antigen-Antibody Complex↗
PubMed1998

Hoarseness and gastroesophageal reflux in children.

The importance of a hoarse voice or voice change in children has not been stressed in the literature in the same way as it has been in adults. We present 21 children who had been suffering from chronic hoarseness for more than three months and had on fibre-optic laryngoscopy findings suggestive of gastroesophageal reflux. None of them had complained of gastroesophageal symptoms. Twenty-four hour pH monitoring revealed that 13 (62 per cent) of these children had gastroesophageal reflux, seven (33 per cent) having gastroesophageal reflux more than three times the upper limit of normal. The pH graphs highlighted frequent refluxes, ranging from 0.4 to 37.4 refluxes per hour (median of 7.3 refluxes/hour). The majority of these refluxes occurred when the child was awake as opposed to asleep, with a median of 14.8 refluxes/hour and 0.9 refluxes/hour respectively (p = 0.0009). The refluxes were classically of short duration. This study suggests that gastroesophageal reflux plays a direct role in the pathogenesis of chronic laryngitis and hoarseness in children.

Child↗
PubMed1998

Dietary treatment for regurgitation--recommendations from a working party.

Regurgitation is a common manifestation in infants below the age of 1 y, and is a frequent reason for counselling of general practitioners and paediatricians. Current recommended therapeutic management starts with parental reassurance and dietary measures, followed by prokinetics. In this paper, the efficacy, safety and nutritional implications of the dietary treatment of regurgitation are evaluated. Industrially prepared thickened feeds may contain cereals of fibres; some have a low lipid content and are casein-predominant. Milk-thickened agents can also be added to regular infant feeding. Formulae claimed as "anti-regurgitation formulae", or positioned as such, should be considered as medical foods or therapeutic diets, and only be available on medical prescription. It is proposed to limit the "anti-regurgitation" (AR) label to those diets which have been proven clinically effective on regurgitation and which are nutritionally safe.

Gastroesophageal Reflux↗
PubMed1998

Site-directed mutagenesis study of a conserved residue in family 10 glycanases: histidine 86 of xylanase A from Streptomyces lividans.

Xylanases from family 10 glycanases contain three conserved histidine residues in their active site. The role of H86 in the structure-function of xylanase A from Streptomyces lividans (XlnA) was studied by site-directed mutagenesis. Six mutant proteins (H86A/E/F/K/Q/W) were produced, purified and characterized. The six mutations reduced the affinity of XlnA towards xylan without having any major effect on the catalytic constant. All these mutations also lowered the pKa of the acid-base catalyst by 0.46-1.94 pH units. The mutations decreased the enzyme stability at 60 degrees C by up to 95% and the transition temperature by 2.2-5.8 degrees C. Unfolding of the protein with guanidine hydrochloride (GdnxHCl) showed that five out of six mutations decreased the concentration required to denature 50% of the XlnA, confirming the importance of H86 for the stability of the enzyme. The increase in m value ¿m=d(deltaG)/d[GdnxHCl]¿ also suggested the involvement of residue H86 in the structure of the denatured state of XlnA. It can be concluded from this study that this active site residue was conserved in family 10 glycanases for its function in maintaining the elevated pKa of the acid-base catalyst and in the stability of the protein, while being of little importance for the activity.

Binding Sites↗