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Biomedical subjects

J Boyer

Publications and source records attributed to J Boyer.

At least 73 records · Page 4Linked to original sources
PubMed1997

Interobserver agreement in the staging of rectal cancer using endoscopic ultrasonography.

BACKGROUND AND STUDY AIMS: In rectal tumors invasion of the rectal fat and perirectal lymph nodes are generally regarded as independent prognostic factors in most prospective series. There are no studies in the literature concerning interobserver agreement on the staging of rectal cancer by endorectal ultrasonography (EUS). The aim of the present study was to assess interobserver agreement using EUS in the TN staging of rectal cancer. PATIENTS AND METHODS: Thirty-seven patients with rectal cancer were investigated at two centers using EUS as part of the pretherapeutic staging (Olympus EUM-3 or EUM-20). All examinations were videotaped and reviewed six months later by four independent observers who assessed the stage of the tumor (from uT1 to uT4) and lymphatic invasion on a blinded basis. When the tumor was assessed as uT3, the observers specified the degree of involvement of the rectal fat (in millimeters). Interobserver agreement was estimated using the kappa coefficient (k) and the intraclass correlation coefficient (ICC). Agreement was classed as poor (k < 0.40), fair to good (0.40 < or = k < 0.75) or excellent (k < or = 0.75). RESULTS: Agreement was fair for uT1 tumors (k = 0.40) and poor for uT2 tumors (k = 0.20). Agreement was good (k = 0.58; CI 0.51 to 0.65) for uT3 tumors; there was a significant interobserver correlation for the exact measure of the extent of rectal fat (ICC = 0.65). The agreement was also good (k = 0.54, CI 0.47 to 0.61) for metastatic lymph nodes. CONCLUSION: As in the case of esophageal cancer, interobserver agreement on the staging of uT2 tumors is poor with EUS. The evaluation of rectal tumors with a poor prognosis shows good interobserver agreement.

Adenocarcinoma↗
PubMed1997

Genetic immunization: a new era in vaccines and immune therapeutics.

DNA inoculation represents a novel approach to vaccine and immune therapeutic development. The direct injection of gene expression cassettes into a living host transforms a number of cells into factories for production of the introduced gene products. Expression of these delivered genes has important immunological consequences and may result in the specific immune activation of the host against the novel expressed antigens. The recent demonstration by laboratories that these immune responses are protective in some infectious disease experimental models as well as cancers is viewed with cautious optimism. Further, the relatively short development times, ease of large-scale production, low development, manufacturing, and distribution costs all combine with immunological effectiveness to suggest that this technology will dramatically influence the production of a new generation of experimental vaccines and immune therapies. It is hoped that DNA inoculation will ultimately lead to new vaccines that are immunologically effective and economically accessible to all nations.

Animals↗
PubMed1997

Development of genetic vaccines for pathogenic genes: construction of attenuated vif DNA immunization cassettes.

OBJECTIVE: To develop a putative immunization cassette using HIV-1 vif accessory gene derived from HIV-1 clinical specimens as a component of a DNA vaccine for HIV-1. METHODS: vif genes were cloned from HIV-1-infected patients and the sequence variation present within the patients was analyzed. Prototypic genetic variants were selected and the ability of these clones to induce humoral and cellular immune responses was studied in animals. The selected protective genetic variants were biologically characterized through transcomplementation assays using primary cells infected with a vif-defective HIV-1 proviral clone. RESULTS: Analysis of vif variants from different patients revealed that vif is highly conserved with the open reading frame remaining intact in vivo. It was shown that attenuated vif clones from HIV-1-infected subjects can effectively induce both humoral and cellular responses against Vif protein in mice. Evaluation of the cellular responses in vitro using human cellular targets infected with a clinical HIV-1 isolate showed that vif clones could induce cellular responses capable of destroying the virus. CONCLUSIONS: The vif variants developed in this study exhibited non-productive phenotypes, yet were capable of inducing specific immune responses against HIV-1. These constructs could be used as part of a DNA vaccine strategy for HIV-1. This vaccine adaptation strategy could be used for the development of immunogens for any pathogen resulting in cross-reactive immunity and attenuated gene pathogenesis.

AIDS Vaccines↗
PubMed1997

[Treatment of common bile duct lithiasis: first-line endoscopic sphincterotomy and celioscopic cholecystectomy].

The aim of this study was to assess retrograd cholangiogram findings and first-line endoscopic sphincterotomy followed by laparoscopic cholecystectomy for the treatment of main bile duct lithiasis. Clinical, biological and echographic criteria predictive of main bile duct lithiasis were observed in 125 patients (32 men, 93 women, mean age 44.2 years) who underwent retrograde cholangiography. Results suggested lithiasis of the main bile duct in 105 case (87.5%) and were confirmed at endoscopic sphincterotomy in 99. There were no deaths; four complications occurred (3 moderate cases of pancreatitis, 1 cholecystitis). Conversion was required in 11.6%, usually because of difficulties in dissecting. No residual lithiasis was observed. Mean duration of hospitalization was 11.4 days. This sequential treatment scheme for main bile duct lithiasis appears to be effective, minimally invasive and safe.

Adult↗
PubMed1996

[Endoscopic retrograde cholangiography and endosonography. Respective indications in case of suspicion of common bile duct calculi].

The new methods for diagnosis and treatment of biliary lithiasis, including laparoscopic cholecystectomy, have encouraged work into new means of searching for a stone in the main bile duct. The management strategy for an individual patient can only be determined on the basis of the clinical situation and the relative expectations of the different diagnostic and therapeutic methods available. The current strategy does not take into consideration the contribution of magnetic resonance cholangiography which must be evaluated in comparison with endosonography. In general, when operative risk is moderate or low, endosonography is indicated, with or without sphincterotomy. In high-risk patients, endoscopic retrograde cholangiography would be indicated. Of course, this strategy depends on the facilities available and the experience of the surgical team. A self-assessment procedures will help determine the most cost-effective strategy.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1996

Sequence and analysis of a 26.9 kb fragment from chromosome XV of the yeast Saccharomyces cerevisiae.

We have determined the nucleotide sequence of a fragment of chromosome XV of Saccharomyces cerevisiae cloned into cosmid pEOA048. The analysis of the 26,857 bp sequence reveals the presence of 19 open reading frames (ORFs), and of one RNA-coding gene (SNR17A). Six ORFs correspond to previously known genes (MKK1/SSP32, YGE1/GRPE/MGE1, KIN4/KIN31/KIN3, RPL37B, DFR1 and HES1, respectively), all others were discovered in this work. Only five of the new ORFs have significant homologs in public databases, the remaining eight correspond to orphans (two of them are questionable). O5248 is a probable folypolyglutamate synthetase, having two structural homologs already sequenced in the yeast genome. O5273 shows homology with a yeast protein required for vanadate resistance. O5268 shows homology with putative oxidoreductases of different organisms. O5257 shows homology with the SAS2 protein and another hypothetical protein from yeast. The last one, O5245, shows homology with a putative protein of Caenorhabditis elegans of unknown function. The present sequence corresponds to coordinates 772,331 to 799,187 of the entire chromosome XV sequence which can be retrieved by anonymous ftp (ftp. mips. embnet. org).

Agglutinins↗
PubMed1996

Selective modulation of membrane sphingomyelin fatty acid turnover by nigericin. A study in the rat reticulocyte.

Exposure of rat reticulocytes to Nigericin produced a selective modulation of fatty acid incorporation into sphingomyelin (SM) of the cell membrane, via changes in SM acylation kinetics. At physiological fatty acid concentration, Nigericin accelerated 8-fold SM acylation by decreasing the apparent K(m) for oleate from 14.7 microM to 2.0 microM. The response was diminished in high K(+)-containing media, suggesting an effect of Nigericin as K+ transporter. This constitutes a novel piece of evidence for the important role of ions in SM metabolism.

Acylation↗
PubMed1996

Endoscopic ultrasonographic signs of portal hypertension in cirrhosis.

BACKGROUND: Endoscopic ultrasonography (EUS) has been suggested to investigate portal hypertension (PHT). We compared EUS and endoscopy in the exploration of PHT in cirrhosis. METHODS: In 58 patients with cirrhosis and 16 controls, the presence of esophageal varices and gastric varices was recorded by both endoscopy and EUS, peridigestive varices and perforating veins by EUS. Relationships of patterns with each other and with clinical and biologic data were evaluated. RESULTS: In patients with cirrhosis: esophageal varices were found by endoscopy and EUS in 88% and 55% of cirrhotic cases (p < 0.01), and gastric varices in 17% and 41%, respectively (p < 0.01). Perforating veins, below the gastroesophageal junction, were diagnosed by EUS in 40% of cases and never in controls. A significant relationship was found between perforating veins and the following patterns: peri-digestive varices, gastric varices at EUS, and esophageal varices at endoscopy. In patients with and without cirrhosis: after multivariate analysis, only esophageal varices at endoscopy were independently related to cirrhosis. However, in Child-Pugh class A patients, both esophageal varices and perforating veins were independently related to cirrhosis (diagnostic accuracy, 92%). CONCLUSIONS: EUS is of limited value in the diagnosis of cirrhosis because it gives little additional information to upper gastrointestinal endoscopy. The relationships between perforating veins, varices, and peridigestive varices support the hypothesis that perforating veins are important in the pathogenesis of esophageal and gastric varices.

Endoscopy, Gastrointestinal↗
PubMed1996

Pharmacological and second messenger signalling selectivities of cloned P2Y receptors.

1. Four different phospholipase C (PLC)-activating P2Y receptors have been cloned and stably expressed in 1321N1 human astrocytoma cells. These include the human homologues of the P2Y1, P2Y2 and P2Y4 receptors and the rat homologue of the P2Y6 receptor. 2. The nucleotide selectivities of these four receptors have been compared directly by measuring inositol phosphate accumulation in response to nucleotides under conditions in which the initial purity and stability of agonist was rigidly assured and quantitatively assessed. 3. The P2Y1 receptor is specific for adenine nucleotides and slightly more sensitive to disphosphates than triphosphates. When expressed in 1321N1 astrocytoma cells, it couples selectively to the stimulation of PLC and not to the inhibition of adenylyl cyclase. 4. The P2Y2 receptor is activated by UTP and ATP with similar potency and is not activated by nucleoside diphosphates. Diadenosine terraphosphate is a potent agonist at this receptor. 5. The P2Y4 receptor is highly selective for UTP over ATP and is not activated by nucleoside disphosphates. 6. The P2Y6 receptor is activated most potently by UDP, but weakly or not at all by UTP, ADP and ATP. The P2Y6 receptor appears to be identical to the uridine nucleotide-specific receptor previously characterized in C6-2B rat glioma cells. 7. We have identified a P2Y receptor on C6 glioma cells that inhibits adenylyl cyclase but has no effect on PLC. This receptor exhibits a pharmacological selectivity similar but not identical to that of the P2Y1 receptor. When the P2Y1 receptor was expressed in these C6 cells, it conferred an inositol lipid signalling response to adenine nucleotides that was pharmacologically identical to that of the P2Y1 receptor. Thus, the P2Y receptor of C6 glioma cells represents an additional receptor that exhibits the classical pharmacological selectivity of a P2Y1-R, but which couples to adenylyl cyclase rather than to PLC.

Adenosine Triphosphate↗
PubMed1996

Evidence of airway obstruction in children with idiopathic scoliosis.

Restrictive pulmonary function abnormalities are reported in children and adolescents with idiopathic scoliosis. We hypothesized that spirometry alone, without more extensive testing, including the measurement of lung volumes, is inadequate in characterizing lung function in these children and may miss obstructive abnormalities including significant gas trapping. To examine this hypothesis, we reviewed the pulmonary function tests of 44 children (36 female, 8 male) between the ages of 10 and 18 years with idiopathic scoliosis prior to surgical correction. Spirometry, measurements of lung volumes with both plethysmographic and helium dilution techniques, and bronchodilator response were analyzed for evidence of reversible airway obstruction and gas trapping. Eighteen of 44 (41%) subjects had significant restriction. Only 3 (7%) subjects met standard criteria for airflow obstruction. However, 20 (46%) subjects had an elevated total gas volume by plethysmography-functional residual capacity by helium dilution ratio indicative of moderate or severe gas trapping, 10 (23%) subjects showed mild gas trapping, 8 (18%) subjects had a ratio suggestive of gas trapping, and only 6 (14%) subjects were normal. Additionally, significant improvement in airway mechanics was noted after bronchodilator administration. Specific conductance improved in all subjects, with a mean increase of 62% +/- 8.0 (p<0.001). The residual volume-total lung capacity ratio and total gas volume by plethysmography also decreased significantly (mean decrease, 22.5% +/- 3.0 and 15% +/- 1.0, respectively, p<0.001) in response to inhaled bronchodilators. In conclusion, although restrictive defects are commonly present in children with idiopathic scoliosis, significant gas trapping and responses to bronchodilators also commonly occur. These abnormalities may be missed without extensive pulmonary function testing.

Adolescent↗
PubMed1996

[Mucinous ductal ectasia. Apropos of 2 cases].

Mucinous ectasia of the pancreas ducts is a recently described cystic lesion which usually occurs in acute pancreatitis. Endoscopic retrograde pancreatography provides diagnosis. Mucinous ductal ectasia is considered to be a precancerous lesion. Surgical exeresis is recommended. Our two cases emphasize the difficulties encountered for differential diagnosis with other cystic lesions of the pancreas.

Aged↗
PubMed1995

Purification and properties of a monoacylglycerol lipase in human erythrocytes.

A membrane-bound monoacylglycerol lipase (MAGL) activity, previously demonstrated in intact human erythrocytes [Boyer, Somma, Vérine, L'Hôte, Finidori, Merger and Arnaud (1981) J. Clin. Endocrinol. Metab. 53, 143-148], has now been purified to apparent homogeneity by a five-step procedure involving solubilization in CHAPS and sequential chromatographies on Sephacryl S-400, DEAE-Trisacryl, Zn(2+)-chelating Sepharose and Superose 12 columns. The purified protein has a molecular mass of 68 +/- 2 kDa, as determined by SDS/PAGE and gel filtration, suggesting that the enzyme behaves as a monomer. The concentration-dependence of MAGL activity with monooleoylglycerol, the preferred substrate showed kinetics typical of an interfacial lipolytic enzyme displaying optimal activity on emulsified substrate particles; apparent Km values were 0.27 mM and 0.49 mM for the sn-1(3)- and sn-2-isomers respectively. MAGL had no, or negligible, activity towards tri-oleoylglycerol, di-oleoylglycerol, oleoylcholesterol, oleoyl-CoA and phosphatidylcholine; it was inhibited by di-isopropylfluorophosphate, PMSF and diethyl p-nitrophenyl phosphate, suggesting that MAGL is a serine hydrolase. MAGL activity was not modified by bile salt or apolipoprotein C-II, whereas a dose-dependent inhibition was observed with apolipoprotein A-I.

Apolipoprotein A-I↗