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J Boisvert

Publications and source records attributed to J Boisvert.

At least 19 recordsLinked to original sources
PubMed2001

Quantitative analysis of hepatitis C virus in peripheral blood and liver: replication detected only in liver.

Prior studies seeking evidence of viral replication in peripheral lymphocytes of hepatitis C virus (HCV)-infected patients have yielded conflicting results. This study sought to quantitatively determine whether a permissive HCV cell interaction could be detected in leukocytes from infected patients. Peripheral leukocytes from chronically infected patients were purified and were tested for HCV RNA. The results show that virus load is highest in B cells. Other subsets of peripheral leukocytes consistently had very low levels of viral RNA or were negative. Negative-strand HCV was found only in hepatocytes. To determine whether HCV replication could be induced by activation, B cells from HCV-infected patients were stimulated in vitro. No HCV replicating in peripheral leukocytes was detected by a highly sensitive assay. If HCV replication occurs in the leukocyte subsets analyzed here, it is at extremely low levels or occurs under alternate physiological conditions.

Adult↗
PubMed2001

CCR7 expression and memory T cell diversity in humans.

CCR7, along with L-selectin and LFA-1, mediates homing of T cells to secondary lymphoid organs via high endothelial venules (HEV). CCR7 has also been implicated in microenvironmental positioning of lymphocytes within secondary lymphoid organs and in return of lymphocytes and dendritic cells to the lymph after passage through nonlymphoid tissues. We have generated mAbs to human CCR7, whose specificities correlate with functional migration of lymphocyte subsets to known CCR7 ligands. We find that CCR7 is expressed on the vast majority of peripheral blood T cells, including most cells that express adhesion molecules (cutaneous lymphocyte Ag alpha(4)beta(7) integrin) required for homing to nonlymphoid tissues. A subset of CD27(neg) memory CD4 T cells from human peripheral blood is greatly enriched in the CCR7(neg) population, as well as L-selectin(neg) cells, suggesting that these cells are incapable of homing to secondary lymphoid organs. Accordingly, CD27(neg) T cells are rare within tonsil, a representative secondary lymphoid organ. All resting T cells within secondary lymphoid organs express high levels of CCR7, but many activated cells lack CCR7. CCR7 loss in activated CD4 cells accompanies CXC chemokine receptor (CXCR)5 gain, suggesting that the reciprocal expression of these two receptors may contribute to differential positioning of resting vs activated cells within the organ. Lymphocytes isolated from nonlymphoid tissues (such as skin, lung, or intestine) contain many CD27(neg) cells lacking CCR7. The ratio of CD27(neg)/CCR7(neg) cells to CD27(pos)/CCR7(pos) cells varies from tissue to tissue, and may correlate with the number of cells actively engaged in Ag recognition within a given tissue.

Biomarkers↗
PubMed2001

Direct functional analysis of epitope-specific CD8+ T cells in peripheral blood.

The functional status of virus-specific CD8+ T cells is important for the outcome and the immunopathogenesis of viral infections. We have developed an assay for the direct functional analysis of antigen-specific CD8+ T cells, which does not require prolonged in vitro cultivation and amplification of T cells. Whole blood samples were incubated with peptide antigens for <5 h, followed by staining with peptide-MHC tetramers to identify epitope-specific T cells. The cells were also stained for the activation marker CD69 or for the production of cytokines such as interferon-gamma (IFNgamma) or tumor necrosis factor-alpha (TNFalpha). With the combined staining with tetramer and antibodies to CD69 or cytokines the number of antigen-specific CD8+ T cells as well as the functional response of each individual cell to the cognate antigen can be determined in a single experiment. Virus-specific CD8+ T cells that are nonfunctional, as well as those that are functional under the same stimulating conditions can be simultaneously detected with this assay, which is not possible by using other T-cell functional assays including cytotoxicity assay, intracellular cytokine staining, and enzyme-linked immunospot (ELISPOT) assay.

Antigens, Viral↗
PubMed2001

Bonzo/CXCR6 expression defines type 1-polarized T-cell subsets with extralymphoid tissue homing potential.

Chemokine receptor expression is finely controlled during T-cell development. We show that newly identified chemokine receptor Bonzo/CXCR6 is expressed by subsets of Th1 or T-cytotoxic 1 (Tc1) cells, but not by Th2 or Tc2 cells, establishing Bonzo as a differential marker of polarized type 1 T cells in vitro and in vivo. Priming of naive T cells by dendritic cells induces expression of Bonzo on T cells. IL-12 enhances this dendritic cell-dependent upregulation, while IL-4 inhibits it. In blood, 35-56% of Bonzo+ CD4 T cells are Th1 cells, and 60-65% of Bonzo+ CD8 T cells are Tc1 cells, while few Bonzo+ cells are type 2 T cells. Almost all Bonzo+ Tc1 cells contain preformed granzyme A and display cytotoxic effector phenotype. Most Bonzo+ T cells lack L-selectin and/or CCR7, homing receptors for lymphoid tissues. Instead, Bonzo+ T cells are dramatically enriched among T cells in tissue sites of inflammation, such as rheumatoid joints and inflamed livers. Bonzo may be important in trafficking of effector T cells that mediate type 1 inflammation, making it a potential target for therapeutic modulation of inflammatory diseases.

Arthritis↗
PubMed2000

Lymphocyte CC chemokine receptor 9 and epithelial thymus-expressed chemokine (TECK) expression distinguish the small intestinal immune compartment: Epithelial expression of tissue-specific chemokines as an organizing principle in regional immunity.

The immune system has evolved specialized cellular and molecular mechanisms for targeting and regulating immune responses at epithelial surfaces. Here we show that small intestinal intraepithelial lymphocytes and lamina propria lymphocytes migrate to thymus-expressed chemokine (TECK). This attraction is mediated by CC chemokine receptor (CCR)9, a chemoattractant receptor expressed at high levels by essentially all CD4(+) and CD8(+) T lymphocytes in the small intestine. Only a small subset of lymphocytes in the colon are CCR9(+), and lymphocytes from other tissues including tonsils, lung, inflamed liver, normal or inflamed skin, inflamed synovium and synovial fluid, breast milk, and seminal fluid are universally CCR9(-). TECK expression is also restricted to the small intestine: immunohistochemistry reveals that intense anti-TECK reactivity characterizes crypt epithelium in the jejunum and ileum, but not in other epithelia of the digestive tract (including stomach and colon), skin, lung, or salivary gland. These results imply a restricted role for lymphocyte CCR9 and its ligand TECK in the small intestine, and provide the first evidence for distinctive mechanisms of lymphocyte recruitment that may permit functional specialization of immune responses in different segments of the gastrointestinal tract. Selective expression of chemokines by differentiated epithelium may represent an important mechanism for targeting and specialization of immune responses.

Animals↗
PubMed1999

Quantitative analysis of hepatitis C virus-specific CD8(+) T cells in peripheral blood and liver using peptide-MHC tetramers.

It is believed that the hepatitis C virus (HCV)-specific CD8(+) cytotoxic T lymphocytes (CTLs) play a role in the development of liver cell injury and in the clearance of the virus. To develop a direct binding assay for HCV-specific CTLs, we generated two peptide-MHC tetramers by using the recombinant HLA A2.1 molecule and A2-restricted T cell epitopes of the HCV NS3 protein. With these reagents we are able to detect specific CD8(+) cells in the blood of 15 of 20 HLA-A2(+), HCV-infected patients, at a frequency ranging from 0.01% to 1.2% of peripheral CD8(+) T cells. Phenotypic analysis of these specific cells indicated that there is a significant variation in the expression of the CD45 isoforms and CD27 in different patients. A 6-hour incubation of one patient's blood with NS3 peptides resulted in the activation of the epitope-specific CD8(+) cells, as indicated by their expression of CD69 and IFN-gamma. We also detected NS3-specific CD8(+) T cells in the intrahepatic lymphocyte population isolated from liver biopsies of two HCV-infected patients. The frequency of these specific CD8(+) cells in the liver was 1-2%, at least 30-fold higher than in the peripheral blood. All of the intrahepatic NS3-specific CD8(+) T cells were CD69(+), suggesting that they were activated CTLs. Direct quantitation and characterization of HCV-specific CTLs should extend our understanding of the immunopathogenesis and the mechanism of clearance or persistence of HCV.

Antigens, CD↗
PubMed1999

Liver disease in children with cystic fibrosis: US-biochemical comparison in 195 patients.

PURPOSE: To determine if abnormal liver architecture at ultrasonography (US) is related to abnormal function in children with cystic fibrosis (CF). MATERIALS AND METHODS: For 1 year, all 195 children (112 boys, 83 girls; mean age, 8.5 years) attending a CF clinic underwent abdominal US and a standard set of liver function tests. Aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyltransferase levels were analyzed. US signs were interpreted as follows: hypoechogenicity with prominent portal tracks as edema, hyperechogenicity as steatosis, and increased attenuation and nodules within or at the edge of the liver as cirrhosis. Signs of portal hypertension also were sought. US signs were compared with liver function test results. RESULTS: Liver sonograms were abnormal in 38 children (19%); of these, 24 (63%) had abnormal test results. The 157 children with normal liver architecture had a much lower prevalence of biochemical abnormality (33 patients [21%]; P < or = .001). All eight children with signs of portal hypertension had abnormal test results. Fourteen (82%) of 17 children with signs of cirrhosis had abnormal liver function. Eight (57%) of 14 patients with signs of steatosis had abnormal function. Diffuse hypoechogenicity of the liver with prominent portal tracks in 16 patients was associated with abnormal function in only five patients. CONCLUSION: The relation between abnormal liver architecture at US and results of three liver function tests in children with CF was significant. The most specific US abnormalities related to abnormal function are signs suggestive of portal hypertension and cirrhosis.

Child↗
PubMed1997

Quantification of ketoprofen enantiomers in human plasma based on solid-phase extraction and enantioselective column chromatography.

An HPLC method for the quantification of ketoprofen enantiomers in human plasma is described. Following extraction with a disposable C18 solid-phase extraction column, separation of ketoprofen enantiomers and I.S. (3,4-dimethoxy benzoic acid) was achieved using a chiral column [Chirex 3005; (R)-1-naphthylglycine 3,5-dinitrobenzoic acid] with the mobile phase, 0.02 M ammonium acetate in methanol, set at a flow-rate of 1.2 ml/min. Baseline separation of ketoprofen enantiomers and I.S., free from interferences, was achieved in less than 20 min. The calibration curves (n = 14) were linear over the concentration range of 0.16 to 5.00 micrograms/ml per enantiomer [mean r2 of 0.999 for both enantiomers, root mean square error were 0.015 for R(-) and 0.013 for S(+)]. The inter-day coefficient of variation for duplicate analysis of spiked samples was less than 7% and the accuracy was more than 93% over the over the concentration range of 0.2 to 4.0 micrograms/ml for individual enantiomer using 1 ml of plasma sample. This method has been applied to a pharmacokinetic study from healthy human volunteers following the administration of a ketoprofen extended release product (200 mg). This method is simple, fast and should find wide application in monitoring pharmacokinetic studies of ketoprofen.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1992

Intussusception in children: reliability of US in diagnosis--a prospective study.

To assess the diagnostic value of ultrasound (US) in clinically suspected acute intestinal intussusception in children, the authors prospectively compared US and enema studies in 83 episodes. None of the cases negative at US proved to be intussusception at enema study (negative predictive value = 100%). The sensitivity of US was 100%, and the specificity was 88%. Most of the sonograms were initially obtained and examined by residents. Several unsuspected abnormalities were also found with US. The authors conclude that a few months of training in US appears to be sufficient for high-accuracy investigation of clinically suspected intussusception, enabling selection of those patients in need of an enema.

Barium Sulfate↗
PubMed1992

Development of the fetal brain in the second trimester: an anatomic and ultrasonographic demonstration.

The authors provide an anatomic and ultrasonographic description of the fetal brain from the 16th to the 27th week of development. During the second trimester the primitive brain is smooth and homogeneous and has few sulci and relatively large lateral ventricles. The cerebral hemispheres consist largely of cells migrating from the periventricular germinal matrix to the primitive cortex. The "featureless" hemispheres yield homogeneous ultrasonographic images very different from the more complex and familiar cerebral anatomy of fetuses and premature babies in the third trimester.

Brain↗
PubMed1991

Prenatal diagnosis of fetal anomalies during the second trimester of pregnancy: their characterization and delineation of defects in pregnancies at risk.

During a follow-up study of 19,790 pregnancies at risk for a genetic disease, from 1968 to 1989, 1083 fetuses were found to have an anomaly during the second trimester, leading to 977 terminations of pregnancy. Neural tube defects (31.4 per cent), chromosomal disorders (27.1 per cent), and Mendelian or multifactorial diseases (10.6 per cent) were the main causes of fetal anomaly. More than half (52.9 per cent) of the fetal anomalies were detected by routine ultrasound examination. Forty-two per cent of cystic hygromas were secondary to a chromosomal defect. We stress the importance of a comprehensive fetal and newborn examination to ensure an accurate diagnosis so that subsequently accurate counselling can be provided.

Abdominal Muscles↗
PubMed1991

In utero sonographic diagnosis of diaphragmatic hernia with hepatic protrusion into the pericardium mimicking an intrapericardial tumour.

A case of right-sided congenital diaphragmatic hernia was detected at 33 weeks of gestation. Fetal echocardiography revealed the presence of an intrapericardial mass (3.5 x 3 cm) localized at the right of the heart and surrounded by a massive pericardial effusion. This mass had the same echogenicity as the liver, with which it shared vascular channels. The diagnosis of right diaphragmatic hernia with protrusion of hepatic tissue into the pericardial sac and secondary pericardial effusion was made and confirmed after birth. In utero diagnosis of this anomaly enabled correct assessment of perinatal risk, and optimal fetal and infant management.

Adult↗
PubMed1991

Antenatal diagnosis of ovarian cysts: natural history and therapeutic implications.

A retrospective study from 1980 to 1990 shows 29 ovarian cysts in 27 patients diagnosed by prenatal ultrasound performed between 28 and 38 weeks of gestation. Ten patients underwent surgery, 17 patients were observed with serial ultrasound. Delayed good quality sonograms after spontaneous resolution of the cyst in a selected group of 7 patients showed restoration of a normal ovarian anatomy. The size of the cyst and/or its sonographic characteristics are the 2 main factors for deciding a conservative or a surgical management.

Female↗
PubMed1990

Normal portal venous diameter in children.

A study was conducted on 156 children, in whom the portal veins were measured using standard real time ultrasonography. Knowledge of the normal dimension may be important in patients with liver disease.

Adolescent↗
PubMed1990

Fetal lobation. An anatomo-ultrasonographic correlation.

Remnants of the fusion of fetal renunculi have been mistaken for renal scars or tumors. We compared anatomic cuts of 24 cadaveric kidneys with fetal lobation (ages ranged from 16 weeks gestation to 49 years) to identical ultrasonographic sections performed in a water bath and to sonograms of healthy persons of similar ages as the cadavers. Fetal lobation was characterized as follows: there were fine, linear demarcations indenting the renal surface, separating normal lobes, consisting of a central pyramid and surrounding cortex. Separate renunculi seen in early fetal life progressively fuse throughout gestation, leaving interlobar grooves. During the third trimester, the renal surface becomes smoother and the interlobar grooves become invisible. One prominent indentation of the renal surface, the interrenuncular junction, incorporates perirenal fat and invaginates the anterior surface of the upper third of the kidney to the hilum and is the most easily visible remnant of fetal lobation. The sharply defined linear remnants of interlobar grooves should not be mistaken for scars, which are wider, less well defined and always associated with loss of renal cortex.

Adolescent↗
PubMed1987

Investigation of childhood blunt abdominal trauma: a practical approach using ultrasound as the initial diagnostic modality.

During a 5.5-year retrospective study (1979-84) 170 children with blunt abdominal trauma were investigated with intravenous urography (IVU), ultrasound (US) and scintigraphy. For the investigation of the last 71 children (after 1982) a 4th generation CT scanner was available in the same department. The results of radiologic investigations were compared with clinical outcome in 157 and results at laparotomy in 13 children. During the study period, real time US became the first line screening tool, and was combined with IVU in suspected renal trauma. In spite of permanent accessibility of CT since November 1982, the latter was used only in complex diagnostic problems or in children with multiple injuries (8% of the series). There were no deaths resulting from abdominal trauma. During the study, the incidence of splenectomy and exploratory laparotomy decreased, and no diagnostic peritoneal lavage were performed after 1980.

Abdominal Injuries↗
PubMed1987

Management of thyroid nodules in children: a 20-year experience.

The medical records and surgical slides of 58 patients with the diagnosis of thyroid nodules (solitary nodule in 50 patients) are reviewed. The most common cause of thyroid nodules in this series is follicular adenoma (27 patients or 46%). A nuclear scan (technetium or radioactive iodine) was performed in 55 patients, of which 40 showed a cold nodule. Twelve of the 40 cold nodules were malignant (30%). However, for solitary nodules the incidence of cancer is 27%. This last figure is significantly greater than the one recently reported by Hung et al (18.5%). Available diagnostic methods are reviewed and the clinical management as derived from our experience is presented.

Adolescent↗