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C Dupont

Publications and source records attributed to C Dupont.

At least 181 records · Page 10Linked to original sources
PubMed1995

Design, expression, and initial characterization of MB1, a de novo protein enriched in essential amino acids.

Using recently emerging protein folding principles we have designed a protein enriched in the essential amino acids methionine, threonine, lysine and leucine. Our preliminary study of consensus residues (based on charge, hydrophobicity and volume) of natural alpha-helical bundle proteins indicated that the residues M, T, K, and L could be inserted in an alpha-helical bundle structure. We therefore attempted to create a stable de novo protein, highly enriched in these essential amino acids, that would adopt the alpha-helical bundle fold. The design process was an iterative one. The consensus residues (based on the properties profile) for bundle helices were found considering the four helices taken together, helices I to IV individually, or only their N- and C-termini. Using these data, the helices in our de novo protein were designed by inserting the residues M, T, K and L as often as possible at positions where their volume, hydrophobicity and charge match the consensus found in natural bundle helices. Short sequences of strong turn formers were used to join the helices and adjust the predicted p1 to 7.7, while a number of local and global factors were used to refine our design. Further, the sequence was checked to eliminate various known protease targets in E. coli. The sequence of our de novo protein, MB1, is: MAT-EDMTDMMTTLFKTMQLLTK-SEPTA-MDEATKTATTMKNHLQNLMQK-TKNKE DMTDMATTYFKTMQLLTK-TEPSA-MDEATKTATTMKNHLQNLMQK-GVA+ ++ , where dashes separate long helices from short, turn forming linkers. A gene coding for this protein was assembled from synthetic oligonucleotides, then fused to the maltose binding protein gene under the control of a tac promoter. The fusion protein was expressed in E. coli, purified and cleaved to yield maltose binding protein and our de novo protein, MB1. MB1 was found to be helical, to have the expected molecular weight (11 kDa) and the expected content (57%) of the essential amino acids M, T, K and L.

ATP-Binding Cassette Transporters↗
PubMed1995

[Dysphagia with fever revealing mediastinal lymph node tuberculosis. Apropos of 2 cases].

The oesophagus is a rare localization of extrapulmonary tuberculosis. We report 2 cases of tuberculous mediastinal lymph nodes revealed by dysphagia and fever in immunocompetent subjects. With the actual outbreak of tuberculosis, this localization is worth mentioning, as the precocity of the diagnosis and the therapeutic handling is an important prognostic factor.

Adult↗
PubMed1994

[Helicobacter pylori gastric infections in children].

OBJECTIVES: Numerous reports have established the association of Helicobacter pylori and recurrent abdominal pain in children. We investigated the clinical, bacteriological and therapeutic features of our patients seen over a 1 year period. METHODS: We investigated 121 children during 1992 in Hospital Saint Vincent-de-Paul, Paris. At endoscopy, biopsies were taken and sent for histology and bacteriology and urease testing. A decision regarding treatment by amoxicillin and metronidazol was made after positive results of bacteriology and/or histology. RESULTS: Heliobacter pylori was found in 47 antral biopsies after pathology examination with Giemsa staining alone 16 times, bacterial culture 9 times and both methods 22 times. Abdominal pain was the prominent symptom, occurring in 35.5% of Helicobacter pylori+patients. In 25 of the positive negative patients, a nodular gastritis was observed (53.1%) and in 27.6% of them a weight loss or a delay in weight gain. Few patients became after combined treatment with amoxicillin and metronidazol whereas eradication rates after triple therapy with amoxicillin-metronidazol and H2 antagonist or proton pump blocker were higher. CONCLUSION: Helicobacter pylori related gastritis is a common cause of abdominal complaints in children. The most common symptom is recurrent abdominal pain. Antral nodularity is a peculiar endoscopic finding in children. Two-drug therapy associating amoxicillin-metronidazol is often ineffective to eradicate the bacteria whereas eradication rates after triple therapy amoxicillin-metronidazol and H2 antagonist or proton pump blocker are higher.

Adolescent↗
PubMed1994

Site-directed mutagenesis of the catalytic base glutamic acid 400 in glucoamylase from Aspergillus niger and of tyrosine 48 and glutamine 401, both hydrogen-bonded to the gamma-carboxylate group of glutamic acid 400.

Replacement of the catalytic base Glu400 by glutamine in glucoamylase from Aspergillus niger affects both substrates ground-state binding and transition-state stabilization. Compared to those of the wild-type enzyme, Km values for maltose and maltoheptaose are 12- and 3-fold higher for the Glu400-->Gln mutant, with kcat values 35- and 60-fold lower, respectively, for the same substrates. This unusually high residual activity for a glycosylase mutant at a putative catalytic group is tentatively explained by a reorganization of the hydrogen bond network, using the crystal structure of the related Aspergillus awamori var. X100 glucoamylase in complex with 1-deoxynojirimycin [Harris, E. M. S., Aleshin, A. E., Firsov, L. M., & Honzatko, R. B. (1993) Biochemistry 32, 1618-1626]. Supposedly Gln400 in the mutant hydrogen bonds to the invariant Tyr48, as does Glu400 in the wild-type enzyme. For Tyr48-->Trp A. niger glucoamylase kcat is reduced 80-100-fold, while Km is increased only 2-3-fold. Gln401 also hydrogen bonds to Glu400, but its mutation to glutamic acid has only a minor effect on activity. The Tyr48-->Trp and Glu400-->Gln glucoamylases share particular features in displaying unusually high activity below pH 4.0-which reflects lack of the wild-type catalytic base function- and unusually low binding affinity at subsite 2. Both mutants have lost 13-16 kJ mol-1 in transition-state stabilization energy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspergillus niger↗
PubMed1994

[Measuring gastroesophageal reflux in children].

The risk of gastroesophageal reflux in children has been recognized in many situations, particularly in ear, nose and throat affections and in chronic recurrent respiratory diseases. In addition, in the sudden infant death, a certain number of malaises may be directly related to gastroesophageal reflux via a vagal mechanism. Search for improved comfort for babies exposed to painful oessophagitis is another reason for careful evaluation, particularly since effective treatment is available. The evaluation of gastroesophageal reflux aims at identifying the underlying mechanism. Simultaneous recordings of lower sphincter pressures and pH variations demonstrate the essential role of inappropriate sphincter activity. Oesophagitis results from both prolonged exposure to acid and probably to pepsin, leading to local inflammation. The oesophagitis in turns aggravates sphincter hypotonicity. The oesophageal orifice of the diagphragm could also be involved. The clinical examination is essential to distinguish among the myriad of signs observed in infants and children with suspected reflux. When the symptomatology is particularly scant or when the general health status is unaffected further exploration may not be required. If however, respiratory manifestations appear to be a complication of reflux, complimentary tests are needed. While the diagnosis may be confirmed with pH metry, fibroscopy may be needed to evaluate the anatomical situation and the effect of the oesophagitis on the upper digestive tract. Much progress has also been made with endoscopic explorations which can identify cardial insufficiency and precisely describe the anatomy of the hiatal region. Treatment relies basically on prokinetic agents. The effectiveness of postural measures are currently questioned.

Age Factors↗
PubMed1994

[Abdominal pain in children caused by lactose intolerance. Prospective use of the hydrogen breath test].

OBJECTIVES: We performed the breath hydrogen test in children consulting for abdominal pain in order to determine the minimal quantity of lactose required to prove malabsorption with least patient incomfort and to evaluate the effect of an adapted diet in children with a positive test. METHODS: The breath hydrogen test after lactose intake was performed in 109 children (51 boys, 58 girls, mean age 8.2 + 3.2 years, range 3 to 15) seen for unexplained abdominal pain. All these children had complained of abdominal pain daily for at least 6 months and no other cause could be identified. Children with acute or chronic diarrhoea or constipation were excluded. Nineteen children had been transferred from the surgery unit and 6 had been followed by the psychiatry unit. All these children drank milk regularly. RESULTS: The diagnosis of lactose intolerance was established in 83 children (76.1%) on the basis of a hydrogen peak in the breath after lactose ingestion. One-fourth of the children were of French origin and the others had at least one grandparent who was of Mediterranean or African origin. A lactose-free diet was proposed and led to the disappearance of abdominal pain in 24% and a clear improvement in 32%. CONCLUSION: The breath hydrogen test is a simple non-invasive test which allows a selection of children who could benefit from a lactose-free diet although it cannot be used to predict the effect of diet.

Abdominal Pain↗
PubMed1994

Mononuclear cells from infants allergic to cow's milk secrete tumor necrosis factor alpha, altering intestinal function.

BACKGROUND/AIMS: Intestinal dysfunction observed during cow's milk allergy (CMA) is incompletely understood, and neither the effector cells nor the mediators responsible have been clearly identified. This study was undertaken to better characterize the implication of mononuclear cells in food allergy. METHODS: Peripheral blood mononuclear cells (PBMC) from infants with CMA were cultured in the presence of cow's milk proteins (CMP), and the release of tumor necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), and interleukin 4 and 6 was measured. The effect of culture supernatants was tested on HT29 cl.19A intestinal cell monolayers mounted in Ussing chambers. RESULTS: When stimulated by CMP, PBMC from infants with CMA released more TNF-alpha than those from control infants (429 +/- 92 vs. 205 +/- 34 pg/mL). Culture supernatants did not directly stimulate electrogenic chloride secretion by HT29 cl.19A cells, but epithelial barrier capacity was altered as shown by the significant decrease in electrical resistance (85 +/- 17 vs. 135 +/- 14 omega.cm2 in controls) and the increases in intact horseradish peroxidase, [14C]mannitol, and 22Na+ fluxes. These effects were reversed when culture supernatants were neutralized with anti-TNF-alpha antibodies. Recombinant human-TNF-alpha altered the HT29 cl.19A epithelial barrier capacity, and its effect was highly potentiated by IFN-gamma. CONCLUSIONS: These results indicate that during CMA, the high level of TNF-alpha released by mononuclear cells after milk protein challenge acts synergistically with IFN-gamma to increase the intestinal permeability.

Cell Line↗
PubMed1994

Distinct features of upper gastrointestinal endoscopy in the newborn.

Between January 1987 and December 1990, 293 upper GI endoscopic procedures were performed in 219 neonates < 1 month of age. No lesion was found in 57 cases (26%; group 1), whereas esophagitis was present in 158 cases, alone in 45 cases (20.6%; group 2) and associated with gastritis in 113 cases (51.8%; group 3). The association of esophagitis with gastritis seems to be a specific feature of neonates and not older children. The presence of gastritis with esophagitis suggests that a primary peptic mechanism is unlikely to explain all endoscopic findings, although the presence of such a mechanism secondary to esophagitis could contribute to the esophageal lesions. Acute fetal distress was more frequent in group 3 than in the other groups. Symptoms associated with endoscopic lesions in groups 2 and 3 were, respectively, malaise (38 and 42%), hematemesis (4 and 35%), frequent regurgitation (45 and 26%), and difficult feeding and/or failure to thrive (26 and 24%). In Group 3, minor symptoms often led to the diagnosis of severe mucosal lesions, and antireflux therapy elicited prompt relief of clinical symptoms. The causes of neonatal esophagogastritis remain unknown. Wide use of endoscopy in the presence of discrete clinical abnormalities is likely to considerably improve the clinical condition of some children in their first days of life.

Endoscopy, Gastrointestinal↗
PubMed1994

Stimulation by recombinant human growth hormone of growth and development of remaining bowel after subtotal ileojejunectomy in rats.

The impact of human recombinant growth hormone (GH) after massive small bowel resection was studied in 38 weaning female Wistar rats (65 +/- 5 days old; 193 +/- 26 g). Animals underwent a 80% small bowel resection, leaving in place similar lengths of jejunum and ileum. Animals were assigned to four groups: group A (n = 9), small bowel resection only; group B (n = 10), resection and treatment with 0.2 GH units (GHU) s.c. every other day; group C (n = 9), resection and 0.4 GHU; and group D (n = 10), laparotomy without intestinal resection. Twenty-eight days later, weight gain (percentage of initial weight) was 1 +/- 3 in group A, 12 +/- 8 in group B, 12 +/- 9 in group C, and 16 +/- 7 in group D; p < 0.001, groups B-D. Time to recover initial weight was 26.2 +/- 3.3 days in group A; 11.7 +/- 5.4 days in group B (p < 0.001); and 16 +/- 6.1 days in group C (p < 0.001 vs. A). The size of the intestinal remnant after the rats were killed was 1.3 +/- 0.6 cm (13 +/- 10% of initial length) in A; 5.15 +/- 2.4 cm (37 +/- 18%) in B (p < 0.01); 4.2 +/- 2.3 cm (33 +/- 20%) in C (p < 0.01 vs. A); and 4.4 +/- 3.5 cm (5.8 +/- 4.9%) in D (p < 0.001 vs A). Villus height and diameter, average number of mitosis per field, and muscular layer and wall thickness were greater in groups A, B, and C than in group D (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Allergy to nondairy proteins in mother's milk as assessed by intestinal permeability tests.

The intestinal permeability test is a noninvasive method which, when done during a food provocation procedure, can detect the deleterious effect of food on the intestinal mucosa in allergic children. We report on a 1-month-old breast-fed boy with a history of regurgitation, diarrhea, difficult feeding, and malaise suggesting food allergy. Intestinal permeability tests were done with the mother's milk and showed breast-milk-induced alterations of intestinal permeability. No improvement occurred in the child's clinical symptoms or in the results of the intestinal permeability test when the mother withdrew dairy products from her diet. Disappearance of the child's symptoms and normalization of intestinal permeability during provocation with the milk were obtained after elimination of egg and pork from the mother's diet. This observation suggests that dietary proteins different from cow's milk antigens may be transferred to breast milk and induce adverse reactions in hypersensitive infants.

Animals↗
PubMed1994

Allergy to cow's milk proteins in mother's milk or in hydrolyzed cow's milk infant formulas as assessed by intestinal permeability measurements.

An intestinal permeability test analyzing the differential urinary elimination of lactulose and mannitol orally ingested at the same dosage allowed us to establish a significant correlation between alterations of intestinal permeability and ingestion of reputedly hypoallergenic foods, breast milk, and hydrolyzed protein formulas in some infants with cow's milk allergy. In all, clinical disappearance of symptoms was observed after removal of milk from the mother's diet and/or elimination from the child's diet of any cow's-milk-based hypoallergenic formula.

Animals↗
PubMed1994

A 2-year study of Helicobacter pylori in children.

From September 1990 to October 1992, Helicobacter pylori was searched for in 426 children, 2 days to 16 years old, requiring upper fibroscopy for various symptoms. H. pylori was detected in 77 children (18.1%). Recurrent abdominal pain was present in 63.3% of the patients with H. pylori versus 48.6% of a control group of 74 age-matched children negative for H. pylori, weight loss was present in 6.5% of the patients versus 0% of the control subjects, and a family history of peptic ulcer was present in 14.2% of the patients versus 5.4% of the controls. Micronodular gastritis was observed in 31 children with H. pylori infection (40.2%). Among the 24 children (31.1%) with H. pylori infection and a normal mucosa at endoscopy, 18 (75%) complained of recurrent abdominal pain. H. pylori was also found in 21 of 38 children (55.2%) being examined because of short stature. These findings indicate that H. pylori should be looked for in children with recurrent abdominal pain with or without weight loss or a family history of peptic ulcer. Its relevance in short-stature syndrome requires further clarification.

Abdominal Pain↗