Search PubMed⌕ Search

Biomedical subjects

C Silvain

Publications and source records attributed to C Silvain.

At least 37 records · Page 2Linked to original sources
PubMed1996

Evaluation of monoclonal antibodies with specificity for human IgA, IgA subclasses and allotypes and secretory component. Results of an IUIS/WHO collaborative study.

51 monoclonal antibodies (McAb) with putative specificity for human IgA, the IgA subclasses, Am allotypes or secretory component (SC) were evaluated for immunoreactivity and specificity by nine laboratories employing immunodiffusion, agglutination, immunohistological assays, immunoblotting and direct binding and competitive inhibition enzyme immunoassays. McAbs specific for IgA PAN (n = 24), IgA1 (n = 7), IgA2 (n = 3), IgA2m(2) (n = 2), non-IgA2m(2) (n = 4) and SC or secretory IgA (n = 5) were identified that were immunoreactive and specific in the assays employed. The McAbs identified as IgA- or SC-reactive were shown to be non-reactive to human IgG, IgM, IgD, IgE, kappa and lambda by direct binding and competitive inhibition immunoassays. Interestingly, no McAbs with restricted specificity for IgA2m(1) were identified. Some McAbs displayed higher affinity and/or better performance in one or several of the assay groups. The IgA- and SC-specific McAbs identified in this international collaborative study have potential as immunochemical reference reagents to identify and quantitate monomeric and polymeric IgA in human serum and secretions.

Animals↗
PubMed1996

Non-steroidal anti-inflammatory drugs and variceal bleeding: a case-control study.

BACKGROUND/AIM: The aim of this case-control study was to assess the risk of bleeding from esophageal varices associated with aspirin and non-steroidal anti-inflammatory drug consumption. METHODS: Between January 1992 and May 1994, patients admitted for bleeding from esophageal or gastric lesions related to portal hypertension were matched with a control patient of the same age and sex, who was free of gastrointestinal bleeding. A structured interview was conducted with the cases and controls to determine drug consumption during the 2 weeks preceding admission. Fifty-nine cases and 59 controls were recruited. RESULTS/CONCLUSIONS: Use of aspirin was more prevalent among the cases than the controls (odds ratio 3.81; 95% confidence interval 1.36-11.64; p = 0.004). This difference remained significant in the subgroups of patients with a first episode of variceal bleeding (odds ratio 3.9; 95% confidence interval 1.2-13.9, p = 0.01), but was not significant in the subgroups of patients with a recurrent episode of variceal bleeding. The use of aspirin was associated with a high risk of a first episode of variceal bleeding, suggesting that patients with portal hypertension should avoid taking these drugs.

Adult↗
PubMed1995

Altered expression of monocyte IgA Fc receptors is associated with defective endocytosis in patients with alcoholic cirrhosis. Potential role for IFN-gamma.

Expression, saturation, and endocytosis of IgA Fc receptors (Fc alpha R) were analyzed in blood phagocytic cells of patients with alcoholic liver cirrhosis (ALC). Surface Fc alpha R expression was decreased in monocytes but not in neutrophils, as evaluated by IgA binding and anti-Fc alpha R mAb. The Fc alpha R of ALC patients were saturated by IgA1 and IgA2. ALC Fc alpha R had a higher M(r) (60 to 90 kDa) than those of controls (55 to 75 kDa) with a similar 32-kDa protein core after N-glycanase treatment, suggesting the expression of Fc alpha R molecules with altered carbohydrate moieties. Treatment of U937 cells with IFN-gamma induced a decrease of surface Fc alpha R expression in a dose-dependent manner, with a similar M(r) as observed for ALC patient Fc alpha R (60 to 90 kDa). Fc alpha R endocytosis was induced by anti-Fc alpha R or IgA. Neutrophils internalized Fc alpha R molecules faster than did monocytes. Endocytosed Fc alpha R co-localized with cathepsin D, suggesting an endolysosomal compartment pathway. In ALC monocytes, Fc alpha R endocytosis was defective, with nearly 50 to 60% of receptors detected on the cell surface even after 90 min at 37 degrees C. Similarly, delayed Fc alpha R endocytosis was observed on IFN-gamma-treated U937 cells as compared with PMA-activated cells. Defective internalization of surface-bound IgA with reflux of IgA to cell surface was also observed on ALC monocytes, but not on normal cells preincubated with patients' plasma, ruling out direct effects of IgA. The inverse correlation between monocyte Fc alpha R levels and serum IgA levels associated with defective endocytosis suggest that altered Fc alpha R expression might contribute to receptor saturation and generation of increased plasma levels of IgA and IgA-immune complexes in ALC patients.

Antibodies, Monoclonal↗
PubMed1995

Value of endoscopic ultrasonography in the diagnosis of common bile duct stones: comparison with surgical exploration and ERCP.

An accurate and safe preoperative method of imaging the common bile duct is essential for the proper diagnosis of calculous biliary tract disease, especially in the current era of laparoscopic cholecystectomy. The value of endoscopic ultrasonography in detecting common duct stones has been reported, albeit in small series. The aim of this retrospective study was to assess the accuracy of EUS in a large series of patients. We compared EUS to direct cholangiography in the evaluation of 422 patients for common duct stones. Ductal stones were imaged by EUS in 168 patients (43.4%). No complications were encountered. EUS failed in 2.3% of cases, ERCP failed in 8.3%, and surgical exploration failed in 0.5%. Comparison of EUS with surgical exploration in 185 patients showed a sensitivity of 94.9%, a specificity of 97.8%, and an accuracy of 95.9%. EUS was compared to ERCP in 219 patients. All common duct stones found by ERCP were evident by EUS. Concordance was obtained in 91.3% of cases. Review of videotapes disclosed 3 false-positives and 16 unequivocal true-positives. We conclude that EUS is a safe and highly accurate means of detecting common duct stones and should be proposed before laparoscopic cholecystectomy in patients at risk of choledocholithiasis.

Adolescent↗
PubMed1995

Phenotypic and functional characteristics of colonic lymphocytes isolated from patients with primary sclerosing cholangitis and inflammatory bowel disease.

Because primary sclerosing cholangitis (PSC) frequently is associated with inflammatory bowel disease, the phenotypic and functional characteristics of lymphocytes isolated from colonic mucosa were studied in patients with primary sclerosing cholangitis (PSC), patients with ulcerative colitis and patients with other colonic and hepatic disorders. To accomplish this, lymphocytes isolated from colonic biopsies obtained at the time of colonoscopy were expanded in vitro in the presence of interleukin 2 (IL2). Cell propagation was similar in patients with PSC with or without associated inflammatory bowel disease but was diminished significantly when compared to results obtained in patients with ulcerative colitis not associated with PSC. The CD4:CD8 ratio of the propagated lymphocytes was increased in patients with PSC compared to controls. The Leu 19+ subset of cells was also increased in PSC patients. In patients with inflammatory bowel disease, increased cytotoxicity was noted at low effector to target cell ratios with SK-HEP (hepatocellular carcinoma) but not RPMI 7451 (cholangiocarcinoma) targets. No differences between PSC patients and controls were observed for NK sensitive and NK resistant targets. Based upon these studies it can be concluded that: 1) expansion of lymphocytes obtained from endoscopic colonic biopsies using recombinant IL2 represents an alternative method by which intestinal lymphocytes can be studied; 2) natural killer cells are increased in the colonic mucosa of patients with primary sclerosing cholangitis; 3) colonic cytotoxic T lymphocytes may be more active in patients with chronic liver disease and particularly those with associated inflammatory bowel disease.

Adult↗
PubMed1994

Randomised trial of prevention of biliary stent occlusion by ursodeoxycholic acid plus norfloxacin.

Biliary stents are liable to clog. We investigated whether a choleretic plus an antibiotic could delay clogging. 20 consecutive patients with a malignant biliary stricture were randomised after endoscopic insertion of a polyethylene stent to receive ursodeoxycholic acid plus norfloxacin (13-15 mg/kg and 400 mg, daily) or conservative treatment. The drug combination was associated with: a longer median patency of first (49 vs 6 weeks) and all stents (38 vs 7 weeks); a prolonged median survival (67 vs 18 weeks); and a shorter mean hospital stay (0.2 vs 1.0 days per week of survival). Thus ursodeoxycholic acid plus norfloxacin may prevent stent clogging.

Administration, Oral↗
PubMed1994

Anatomic and radiologic bases of combined transplantation of liver and small intestine in the pig.

In order to assess the tolerance induced by hepatic transplantation in a multivisceral graft, a model of a transplant combining the liver and small intestine was developed in the pig, using animals of Large White Isogroup O, typed in the system of major incompatibility as "Swine lymphocyte antigen" (SLA), whose weight varied from 30 to 40 kg. In order to limit the duration of warm ischemia, dissection of the graft was performed on the donor animal with respect for the following anatomic features: absence of intestinal attachment to the posterior parietal peritoneum, anti-clockwise torsion of 360 degrees of the intestine around the superior mesenteric a. with the small intestine convolutions on the right and the colonic helix on the left. The bifid pancreas follows this rotation and its resection must respect the vascularisation of the proximal small intestine; the hepatic a. arises from a common trunk with a gastrosplenic branch of the aorta between the crura of the diaphragm and travels sagittally from behind forward toward the liver pedicle, which it reaches ar the upper border of the duodenum; the hepatic a. and its branches are dorsal in relation to the portal vein; the hepatic arterial distribution follows a right-left and antero-posterior systematisation for the six hepatic lobes of this quadruped animal.

Anastomosis, Surgical↗
PubMed1993

Characterization of melatonin binding sites in chicken and human intestines.

The radioligand 2-[125I]iodomelatonin was used to study melatonin binding sites in chicken and human intestines. In the chicken duodenum, 2-[125I]iodomelatonin binding sites were enriched in the musculosa layer (Bmax approximately 1 fmol/mg protein) as compared to the mucosa/submucosa layer (Bmax approximately 0.2 fmol/mg protein). 2-[125I]iodomelatonin bound with a Kd of 68 +/- 18 pM (mean +/- S.E.M., n = 13) and was displaced by melatonin with a Ki of 0.3 nM. The Kd value for 2-[125I]iodomelatonin was increased 2- to 4-fold by a GTP analog, suggesting that the binding sites might be coupled to a G-protein. The affinity order of nine melatonin analogs at the enteric binding sites was in agreement with the pharmacological profile of melatonin receptors described in other tissues. In the human jejunum, 2-[125I]iodomelatonin binding could be observed in the mucosa/submucosa layer (Kd = 150-200 pM, Bmax = 0.7 fmol/mg protein). The radioligand was efficiently displaced by melatonin (Ki = 0.6 nM) but only marginally by N-acetyltryptamine (Ki = 22 microM) and serotonin (Ki = 14 microM).

Animals↗
PubMed1993

A human myeloma IgA with a hybrid heavy chain resulting from putative somatic gene conversion.

A human monoclonal IgA1-IgA2 lambda hybrid molecule was detected in a myeloma patient homozygous for the A2m(1) allotype during a systematic study of monoclonal IgA with subclass-specific monoclonal antibodies (mAb) and the lectin jacalin. This monoclonal immunoglobulin (GAU) reacted with both, although not with all, anti-alpha 1 and anti-alpha 2 mAb. Its heavy (H) chain contained an alpha 1 hinge region as shown by jacalin reactivity, the presence of disulfide-linked H and light chains in spite of its belonging to the IgA2m(1) allotype and amino acid composition of the isolated hinge region. The complete sequence of the H chain was deduced from that of complementary DNA clones from bone marrow cells. The CH1 domain, hinge region and beginning of the CH2 domain and the membrane peptide were encoded by the alpha 1 gene, with an insertion of an alpha 2m(1) gene sequence accounting for the end of the CH2 and part or all of the CH3 domain (sequence identity between the two normal genes precludes a precise definition of breakpoints). The region of the 5' recombination site included a repeat of a six base pair sequence which might play a role in the genetic exchange. The GAU hybrid alpha gene was undetectable in the patient's genomic DNA from polymorphonuclear cells. The genetic event which occurred at the level of the proliferating plasma cell clone is most likely to be a gene conversion.

Antibodies, Monoclonal↗
PubMed1993

Treatment and long-term outcome of chronic radiation esophagitis after radiation therapy for head and neck tumors. A report of 13 cases.

The natural history of chronic radiation esophagitis occurring in previously normal esophagus is still unknown. We describe here the long-term outcome of chronic esophagitis arising after neck irradiation for oropharynx and larynx carcinomas in 13 consecutive adult patients. The first clinical signs of radiation esophagitis were dysphagia or impossibility of oral intake, which appeared within 26 months (range 2-120 months) after the end of radiation for pyriform fossae carcinoma (N = 5), tonsil carcinoma (N = 2), larynx carcinoma (N = 2), pharynx carcinoma (N = 2), base of the tongue (N = 1), and thyroid carcinomas (N = 1). During upper endoscopy, an esophageal stenosis was found in 11 cases and was associated with ulceration in three cases. An isolated esophageal ulceration was present in only two cases. Chronic radiation esophagitis diagnosis was confirmed by histology and surgery in seven cases. In the last six cases, diagnosis was supported by the absence of first cancer relapses within a median follow-up of two years (16 months to nine years) and by endoscopic findings. Seven patients received parenteral or enteral nutrition. Ten patients were treated by peroral dilatations. These treatments allowed nearly normal oral diet in 11/13 patients. Only one patient was lost of follow-up after 20 months. Four patients died from chronic radiation esophagitis. One of these patients died from massive hemorrhage after peroral dilatation. Four patients died of a second carcinoma with no first cancer recurrence. Four patients were alive after six months to nine years of follow-up. Moderate dysphagia was still present, allowing nearly normal oral feeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Hepatic fibrin-ring granulomas in giant cell arteritis.

Hepatic fibrin-ring granulomas were found in a 70-year-old man with prolonged fever and inflammatory syndrome. Diagnosis of giant cell arteritis was confirmed by temporal artery biopsy. Other diseases usually associated with fibrin-ring granulomas in liver, such as Q fever, cytomegalovirus hepatitis, infectious mononucleosis, Hodgkin's disease, non-Hodgkin's lymphoma, allopurinol treatment, and visceral leishmaniasis, were ruled out. This report suggests that giant cell arteritis should be considered as an additional cause of hepatic fibrin-ring granulomas.

Aged↗