Biomedical subjects
Publications and source records attributed to C Dupont.
We report a case of seizures with acute encephalopathy in a female patient under sulfasalazine treatment for polyarthritis. Neurotoxicity secondary to sulfasalazine was suspected. This side effect has seldom been reported in the literature.
The phoA gene technology was used to investigate secreted proteins of the intracellular pathogen Mycobacteriumn avium subspecies paratuberculosis. This led to the identification of sodC, a gene which codes for a copper and zinc cofactored superoxide dismutase (Cu,ZnSOD) which has been implicated as a virulence factor for some pathogens. The predicted protein possessed a 76% identity with Cu,ZnSOD of Mycobacterium tuberculosis. To characterize Cu,ZnSOD from M. avium subspecies paratuberculosis, the gene was cloned and overexpressed in Escherichia coli. The renatured, affinity-purified recombinant protein possessed enzymatic activity that was inhibited by the presence of cyanide, which is characteristic of a Cu,ZnSOD.
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Helicobacter pylori infection is frequent in children. Its incidence in Europe, around 6% in children aged 6-16 years, varies with the socio-economic level and nutritional status. It may reach 46% in Africa and up to 75% in some institutions. Clinical manifestations debated. Vomiting, dyspepsia and acute pain related to ulcer disease may undisputedly be linked to H. pylori, whereas its role in chronic abdominal has yielded contradictory reports. Direct isolation of the bacterium is classically done through perendoscopic antral biopsies followed by culture and histology. Non-invasive diagnosis methods get a wider use in children. Serodiagnosis is reproducible and easy only in older children. The 13C-urea breath test is sensitive and specific, and seems perfectly suitable in pediatrics. The H. pylori stool antigen test for the detection of infection seems promising but not yet of current clinical use. Triple therapy using amoxicillin-clarithromycin (or metronidazole or tinidazole) and anti-secretory agents is recognised as the most efficient association.
Endoxylanases are a group of enzymes that hydrolyze the beta-1, 4-linked xylose backbone of xylans. They are predominantly found in two discrete sequence families known as glycoside hydrolase families 10 and 11. The Streptomyces lividans xylanase Xyl10A is a family 10 enzyme, the native structure of which has previously been determined by x-ray crystallography at a 2.6 A resolution (Derewenda, U., Swenson, L., Green, R., Wei, Y., Morosoli, R., Shareck, F., Kluepfel, D., and Derewenda, Z. S. (1994) J. Biol. Chem. 269, 20811-20814). Here, we report the native structure of Xyl10A refined at a resolution of 1.2 A, which reveals many features such as the rare occurrence of a discretely disordered disulfide bond between residues Cys-168 and Cys-201. In order to investigate substrate binding and specificity in glycoside hydrolase family 10, the covalent xylobiosyl enzyme and the covalent cellobiosyl enzyme intermediates of Xyl10A were trapped through the use of appropriate 2-fluoroglycosides. The alpha-linked intermediate with the nucleophile, Glu-236, is in a (4)C(1) chair conformation as previously observed in the family 10 enzyme Cex from Cellulomonas fimi (Notenboom, V., Birsan, C., Warren, R. A. J., Withers, S. G., and Rose, D. R. (1998) Biochemistry 37, 4751-4758). The different interactions of Xyl10A with the xylobiosyl and cellobiosyl moieties, notably conformational changes in the -2 and -1 subsites, together with the observed kinetics on a range of aryl glycosides, shed new light on substrate specificity in glycoside hydrolase family 10.
OBJECTIVE: To assess the efficacy of highly active antiretroviral treatment (HAART) on AIDS-Kaposi's sarcoma (KS). DESIGN: Prospective cohort of patients followed for 24 months. SETTING: Four referral hospitals of the West Paris metropolitan area. PATIENTS/INTERVENTION: Thirty-nine AIDS-KS patients, 42 +/- 9 years old, who began HAART (HIV-protease inhibitor and two nucleoside analogues) between March and December 1996, were enrolled. One was lost to follow-up at month 12. MAIN OUTCOME MEASURES: KS response, using criteria of the AIDS clinical trials group (ACTG), CD4 cell counts, and plasma HIV-RNA, assessed every 6 months. ACTG TIS staging of KS. RESULTS: Eighteen patients had T1 KS and 21 T0 KS. One patient died from KS at month 6. KS improved progressively, with complete and partial response rates of 46% and 28% at month 24, respectively. Only six patients were still receiving systemic KS therapy at month 24. Complete response was observed in 10 of the 19 patients without systemic KS therapy at inclusion. Patients with complete response at month 24 had higher CD4 cell counts than others (465 +/- 343 versus 185 +/- 167 x 10(6)/l; P < 0.01), but the proportion of patients with HIV-1 RNA < 500 copies/ml was not significantly different. An increase in CD4 cell counts from inclusion to month 12 of > 150 x 10(6)/l [odds ratio (OR), 13.4; 95% confidence interval (CI), 2-82] and T0 KS at inclusion: [OR, 7; 95% CI, 1.1-42] were predictive of complete response at month 24. CONCLUSIONS: HAART appears to have prolonged efficacy on AIDS-KS, even without specific KS therapy, and this effect appears to be linked to the restoration of immune function.
The signal peptide of the xylanase A gene of Streptomyces lividans was replaced by the signal sequence of the cellulase A preceded by a 57 nucleotides (nt) upstream sequence. This latter contains a 5 nt inverted repeat (5'-TGGGAACGCTCCCA). The 3'-end of the inverted repeat contains a 5 nt box (TCCCA), which is complementary to the 16S rRNA of S. lividans. The effects on the production of xylanase resulting from deletions in the inverted repeat and from variations in the length of the box are shown. Removal of the inverted repeat and box decreased the xylanase production by 75%. Increasing the complementarity of the box with the 16S rRNA to 17 nt decreased the production by 90%. A reduction in the length of the inverted repeat, and consequently in the box, from 5 to 4 nt decreased the production by 40%. Preserving the 4 nt inverted repeat but lengthening the box from 5 to 6 nt increased the production by 1.5-fold. Finally, removing the inverted repeat but introducing an 8 nt box increased the xylanase production by 1.9-fold which then averaged 2.3 g/l of xylanase. The most efficient boxes contained 6-8 nt and were located between 14 and 19 nt downstream from the first initiation codon.
OBJECTIVE: To determine the predictors of virological and clinical failure in patients receiving a protease inhibitor as part of triple therapy. METHODS: From the French Hospital Database on HIV, 1402 protease inhibitor-naive patients starting a highly active antiretroviral therapy regimen with ritonavir, saquinavir-hard gel capsule (hgc) or indinavir between July 1996 and March 1997, and with measured HIV RNA at baseline and at 12 months, were studied for progression to a new AIDS-defining event (ADE) or death. Virological failure was defined as plasma HIV RNA > 1000 copies/ml at 12 months. Multivariate analyses were performed using Cox models for clinical outcomes and logistic regression for virological outcomes. RESULTS: During a median follow-up of 14.1 months, 94 (6.7%) patients experienced an ADE or died. At 12 months, 700 patients (49.9%) had virological failure. In the multivariate analysis, baseline CD4 cell count and viral load were found to be independent predictors of both virological and clinical failure. Neither the type of the first protease inhibitor taken nor previous antiretroviral therapy experience was associated with risk of clinical progression. For virological failure, the use of saquinavir-hgc was associated with a significant 1.96-fold increase in risk compared with indinavir; pre-treated patients were at higher risk than antiretroviral therapy-naive patients. CONCLUSION: In this study with large samples of patients, the use of saquinavir-hgc was associated with higher risk of virological failure at 12 months than were ritonavir and indinavir; no differences between protease inhibitors were found for clinical progression. As biases cannot be excluded, a longer duration of follow-up will be necessary to answer the question of whether the results are really discrepant or simply reflect the delay between virological failure and clinical manifestations.
We report on the follow-up of 22 infants allergic to cow's milk proteins who did not tolerate extensively hydrolyzed protein formulas. After successful use of an amino acid-based diet for a duration of 11.8 +/- 8.7 months, evolution differed according to the presence or absence of associated allergy to other foods. Cow's milk protein tolerance occurred earlier in the patients (n = 9) whose allergy was limited to cow's milk proteins and to extensively hydrolyzed protein formulas.
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A thermostability screening assay was developed using an Escherichia coli expression system to express Streptomyces lividans xylanase A (XlnA). The screening system was tested using mutants randomized at position 49 of the S. lividans XlnA gene, a position previously shown to confer thermostability with a I49P point mutation. The library was cloned into an E. coli expression vector and transformed into XL1-blue bacteria. The resulting clones were screened for increased thermostability with respect to wild-type XlnA. Using this assay, we isolated the I49P mutant previously shown to be thermostable, as well as novel I49A and I49C mutants. The I49A and I49C mutants were shown to have 2.8- to 8-fold increase in thermostability over that of wild-type XlnA. The results show that the screening assay can selectively enrich for clones with increased thermostability and is suitable for screening small- to medium-sized libraries of 5000-20,000 clones.
Induction of specific gene expression may provide an alternative or a support to conventional cytotoxic chemotherapy of cancer, as well as to therapy for sickle cell diseases. In this respect, pharmacological induction of expression of the endogenous gamma-globin gene is a realistic approach to therapy of beta-globin disorders. Erythroid differentiation and inhibition of proliferation of the human CML K562 cell line was induced by guanosine 5'-triphosphate (GTP). The hemoglobin production in cells was correlated to an increase in alpha- and gamma-globin mRNA expression. At the transcriptional level, we showed that both the expression of the major erythroid transcription factor GATA-1 (protein and mRNA) and its binding capacity to the gamma-globin gene promoter was transiently increased. Moreover, GTP moderately stimulated the gamma-globin gene promoter after 48 h of treatment. At the post-transcriptional level, GTP treatment led to a drastic increase of the gamma-globin mRNA half-life. This stabilizing effect of GTP was mediated via the 3'-untranslated region (3'-UTR) of the gamma-globin mRNA. In conclusion, mechanism of GTP-mediated differentiation of K562 cells is linked to an early activation of gamma-globin gene transcription followed by a stabilization of its mRNA.
AIM: To describe the clinical course of a dog infected with Mycobacterium bovis causing a granulomatous pneumonia. CLINICAL FINDINGS: The dog initially presented with a persistent cough, inappetence and weight loss. Clinical findings included a fever, dyspnoea and tachypnoea, with haematological evidence of a mild neutrophilia and hypoalbuminaemia. Radiographs of the chest demonstrated a concomitant pneumothorax, pleural effusion, and a consolidated area within the left caudal lung lobe. An exploratory thoracotomy revealed this to be a ruptured granulomatous lesion. Subsequent histopathological, microbiological and genetic studies identified M. bovis as the causal agent. CLINICAL SIGNIFICANCE: Mycobacterium bovis infections should be included in the differential diagnosis of pulmonary disease and pleural effusions in dogs living in regions of New Zealand known to have a high incidence of mycobacterial infection in wildlife and farm animals.
The expression of food protein allergy in man is very heterogeneous, varies with the age of the subject and is to a certain extent genetically determined. Skin prick tests with standardized food extracts are a sensitive method for detection of immunoglobulin E bound to reactive cells such as mast cells. Various tests on cellular immunity have been developed, especially because T-cell mediated reactions are considered to play a role in mainly delayed gastrointestinal reactions to cow's milk proteins. Food allergy may involve the entire gut, from mouth to rectum, including the esophagus. Abnormalities in intestinal permeability are the hallmarks of the inflamed gut, and may contribute to diagnosis of food induced enteropathy. What determines the characteristics of the intestinal inflammatory response is largely the cytokine responses triggered by the pathologic mechanism, whatever its origin, in the stomach, the small intestine, and the colon. A so-called T-helper type 2 response is characteristic of the allergic subject. A secretion of tumor necrosis factor-alpha alpha by blood cells of children allergic to milk was shown. All means of investigation may help in analyzing food substitutes for allergic infants.
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BACKGROUND: The purpose of this multicenter case-control study was to search for causes and risk factors related to the severe upper digestive tract lesions often seen in neonates. METHODS: Case patients were full-term neonates with endoscopically confirmed severe bleeding or ulcerative lesions of the esophagus and/or stomach. Matched control subjects were the next infant born in the same maternity unit who met the same criteria and had no clinical abnormality (and, for ethical reasons, no endoscopy). The analysis was based on 137 case-control pairs and considered data showing the mothers' medical and obstetric background, the infants' clinical status and laboratory results, feeding details, and the State and Trait Anxiety Inventory (STAI) questionnaire, which was used to assess the anxiety of the mothers. RESULTS: Cases and controls did not differ in any demographic or social factors. Antacid and anti-ulcer drugs were used significantly more frequently during the last month of pregnancy by case mothers than by control mothers (28% and 10%, respectively; P < 0.001). Mode of delivery was similar. Case infants more frequently experienced cardiac deceleration during labor and delivery (28% and 12.9%; P = 0.003). Breastfeeding at birth was less frequent for case infants (36% and 49%; P = 0.05). The mean trait anxiety scores did not differ between the two groups, but the mean state anxiety score was higher in case mothers. Multivariate logistic regression found that three factors were independently and significantly associated with esophageal and gastric lesions: use of antacid and antiulcer treatments (odds ratio [OR], 3.9; P < 0.001), cardiac deceleration (OR, 2.2; P = 0.03), and breast-feeding (OR, 0.5; P = 0.02). CONCLUSIONS: Antacid drug use by mothers during the last month of pregnancy was associated with esophageal and gastric lesions. Breast-feeding may play a protective role against severe lesions in neonates.
BACKGROUND: The easiest way to identify the presence of current or past Helicobacter pylori infection is to test for antibodies. The aim of this study was to compare an enzyme-linked immunosorbent assay (ELISA) technique based on the detection of IgG antibodies directed against a global antigenic preparation with immunoblotting based on the analysis of IgG antibody reactivity to separate proteins. METHODS: Sera were collected from 80 children (mean age, 9.9 +/- 4.3 years). The reference tests were microbiologic and histologic examination of gastric biopsies obtained at upper endoscopy. RESULTS: The immunoblotting was more sensitive (100%) and specific (88%) than ELISA (96 and 79%, respectively) in the evaluation of H. pylori infection in children. Its positive predictive value was 92%, and its negative predictive value was 100%. The best performance index of immunoreactive bands to detect antibodies was obtained with the 26-kDa (88.7%), 30-kDa (77.5%) and 19.5-kDa (70%) antigens. Antibodies by immunoblot technique against the CagA antigen were present in 43.1% of children. CONCLUSION: Immunoblotting is highly sensitive and more specific than ELISA in children and provides additional information about the full serologic profile. Immunoblotting may therefore be a useful complement to serology, particularly in cases with doubtful ELISA results.
Food allergies are frequent in infants where digestive signs predominate. The symptoms are extremely variable and most often non-specific. The signs may be immediate or delayed. The pathology of eosinophilia seems to be frequent and may occur in all parts of the intestine. Diagnosis will be orientated to skin tests, prick and/or patch, measurement of IgE and search for eosinophils in digestive biopsies. Exclusion diet of the suspect food, followed by reintroduction of the food will give certainty to the diagnosis.