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C Simard

Publications and source records attributed to C Simard.

At least 37 records · Page 2Linked to original sources
PubMed2000

Enzyme-linked immunosorbent assay for the diagnosis of bovine leukosis: comparison with the agar gel immunodiffusion test approved by the Canadian Food Inspection Agency.

Four commercially available bovine leukemia virus (BLV)-ELISA kits from Europe or the United States were compared to the agar gel immunodiffusion (AGID) test officially approved by the Canadian Food Inspection Agency (CFIA). A total of 1200 cattle serum samples were used. Three ELISA kits based on the envelope glycoprotein (gp51) gave an excellent correlation with the AGID test. The kappa values were 0.998, 0.984, and 0.986 for the ELISA kits #1, #2, and #3, respectively. The ELISA kit based on the p24 core protein was found to be less sensitive than the officially approved AGID test and detected 5.13% of false negatives. Forty BLV AGID strongly positive serum samples were diluted. Based on the dilution experiment, the gp51 ELISA kits were found to be more sensitive than the AGID test kits. They were capable of detecting antibodies in samples diluted up to 1/5000 (kit #1), 1/20 800 (kit #2) and 1/4000 (kit #3), whereas the AGID kit was only capable of detecting antibodies in samples diluted up to 1/100. Based on these observations, the gp51 BLV-ELISA was recognized as an official test method for the serodiagnosis of bovine leukosis in Canada.

Agar↗
PubMed1999

Complete protection of mice from respiratory syncytial virus infection following mucosal delivery of synthetic peptide vaccines.

We have previously shown that intraperitoneal immunization of BALB/c mice with the 14 amino-acid long synthetic peptides G/174-187 and BG/174-187, representing the region 174-187 of the G-glycoprotein from human (H) and bovine (B) respiratory syncytial virus (RSV), respectively, completely protects animals from infection with the corresponding virus. A current goal in vaccine development being the delivery of noninvasive protective antigens via mucosal surfaces, we have evaluated the immunogenicity and protective efficacy of the two peptides when administered to mice by the intranasal (i.n.) route in the presence or absence of the cholera toxin (CT) as a mucosal adjuvant. The two peptides given alone induced the production of RSV-specific circulating IgG, as revealed by ELISA titers of immune sera. When the peptides were administered intranasally with CT, the higher IgG antibody titer which was induced was within the same order of magnitude as that obtained following i.n. immunization with live RSV or intraperitoneal injection with the peptides, thus demonstrating the stimulatory effect of the CT adjuvant. Moreover, although the peptides fail to induce a detectable level of secretory IgA, all animals immunized i.n. with peptide BG/174-187 (plus or minus CT) and all those immunized with peptide G/174-187 mixed with CT were completely resistant to infection by the corresponding virus. To our knowledge, this is the first study reporting that complete protection against a natural pathogen can be elicited by mucosally delivered synthetic peptides. This supports the usefulness of synthetic peptides in prophylactic vaccination.

Administration, Intranasal↗
PubMed1999

Effects of hindlimb suspension on contractile properties of young and old rat muscles and the impact of electrical stimulation on the recovery process.

The purpose of this study was to investigate the effects of hindlimb suspension (HS) on contractile properties of skeletal muscles of young and old rats and to determine the impact of electrical stimulation (ES) on the quality and degree of recovery of these muscles. After 21 days of HS, young soleus (SOL) muscle became faster, but there was no impact on young extensor digitorum longus (EDL) muscle. Twitch tension (Pt) decreased 61% in young and 70% in old SOL muscles. Specific tetanic tension (Po) decreased 53% in young and 64% in old SOL muscles, but again there was no impact on EDL muscle. After a 14-day period of recovery, contraction time (CT), half-relaxation time (RT1/2), Pt and Po returned to control group values in both young and old SOL muscles. Measurements of the contractile properties of young and old skeletal rat muscles showed ES sometimes to be beneficial but also sometimes to be harmful. A 14-day period of recovery, with or without ES, seemed sufficient for many variables to return to control group values.

Aging↗
PubMed1999

Altered expression of myosin heavy chain in the vastus lateralis muscle in patients with COPD.

This study was designed to further characterize peripheral skeletal muscle alterations in patients with chronic obstructive pulmonary disease (COPD) and to evaluate the possible relationship between myosin heavy chain (MyoHC) isoform expression and exercise tolerance in these individuals. MyoHC composition from biopsy of the vastus lateralis muscle was examined in 12 COPD patients (forced expiratory volume in one second (FEV1)=31+/-9% predicted, peak oxygen consumption (V'O2)=15+/-4 mL x kg(-1) x min(-1)) and 10 age-matched normal male subjects (peak V'O2=20+/-5 mL x kg(-1) x min(-1)). The proportion of MyoHC type I was smaller in COPD than in normals (27+/-17% versus 41+/-9%, p<0.05) with an increase in MyoHC type IIa (51+/-15% versus 39+/-9%, p<0.05) and the proportion of MyoHC type IIx being comparable between both groups. A significant relationship was found between peak V'Oo2 mL x kg(-1) x min(-1) and FEV1 % pred (r=0.91, p<0.0001) and the percentage of MyoHC type I (r=0.61, p=0.016). In stepwise multiple regression, only FEV1 % pred was found to be a significant determinant of peak V'O2 (p<0.0001). This variable explained 83% of the total variance of peak V'O2. In summary, this study showed considerable modifications in the phenotypic expression of the myosin heavy chain in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease. An independent effect of myosin heavy chain expression on exercise capacity was not found. These results suggest that chronic inactivity and muscle deconditioning may not be the sole factors explaining peripheral muscle dysfunction in patients with chronic obstructive pulmonary disease.

Aged↗
PubMed1998

Establishment of MAIDS-defective virus-infected B cell lines and their characterization.

Mice inoculated with the murine AIDS (MAIDS)-defective virus develop severe B and T cell dysfunctions. The primary event in the development of this disease is the infection and polyclonal expansion of the target cells of this defective virus, which have been reported to belong to the B cell lineage. To further study the central role that these cells play in the development of MAIDS, we attempted to establish MAIDS-defective virus-infected B cell lines in vitro. We succeeded in establishing two cell lines, SD1 and CSTB5, from the enlarged organs of C57BL/6 mice inoculated with helper-free stocks of the MAIDS-defective virus. Both cell lines are not transplantable in syngeneic C57BL/6 mice or in nude or CD8-/- mice and are apparently not malignant. They both belong to the B lineage, as their immunoglobulin (Ig) genes, but not the T cell receptor (TcR) beta locus, are rearranged, suggesting that they are relatively mature B cells. However, analysis of cell surface marker expression by FACS revealed a surface phenotype similar to that of pre-B cells (MHC I+, MHC II+, B7.2+, sIgM-, sIgG-, kappa-, B220-, CD5-, Thy1.2-, TcR-, CD3-, CD4-, CD8-, Mac-1-, 33D1-). Additionally, the CSTB5 cells express CD40 and the SD1 cells express CD43. Both cell lines contain the MAIDS-defective provirus and express the expected 4.2-kb viral RNA and the corresponding Pr60gag protein. The CSTB5 cells are nonproducer, while the SD1 cell line produces what appears to be an endogenous MuLV. The phenotype of these cell lines is very similar to what is known about the target B cells of this virus in vivo. These new established cell lines are likely to be useful in elucidating the mechanism(s) by which the MAIDS-defective virus causes its target B cells to proliferate and induce T cell anergy in infected animals.

Animals↗
PubMed1998

Post-transcriptional control of c-myc RNA during early development analyzed in vivo with a Xenopus-axolotl heterologous system.

We have set up a heterologous in vivo system to study gene regulation at the post-transcriptional level during early development. This system uses two amphibian species, Xenopus laevis and Ambystoma mexicanum (axolotl), the development of which is three to four times slower than that of X. laevis. The stability of three different synthetic X. laevis c-myc transcripts was followed after injection into fertilized axolotl eggs. One transcript is 2.2 kilobases (kb) long (full-length). The second is 1.5-kb long with most of the 3' untranslated region (3'UTR) removed, and the third corresponds to the 3'UTR (0.7-kb). The behavior of the endogenous axolotl c-myc RNA was compared with the exogenous injected c-myc transcripts. Our results show the existence of several developmental timers controlling degradation of the c-myc molecules. The first is activated at oocyte maturation and affects both the endogenous and exogenous (2.2- and 1.5-kb) transcripts containing the coding regions. A second timer could be linked to the number of cell divisions since fertilization (6th-7th cleavages) and involves the endogenous c-myc RNAs. Another timer could involve the c-myc mRNA molecule itself, because when injected into axolotl eggs, the half-life of the 2.2-kb X. laevis transcript appears to be independent of the axolotl context. After injection into axolotl fertilized eggs, the behavior of this X. laevis full-length c-myc molecule reveals an unexpected increase in the intensity of its autoradiographic signals. This increase occurs independently of events linked to mid-blastula transition and preliminary investigations are discussed.

Amanitins↗
PubMed1998

Histochemical and morphological characteristics of the vastus lateralis muscle in patients with chronic obstructive pulmonary disease.

PURPOSE AND METHODS: In this study, we examined the fiber-type proportions, cross-sectional areas (CSA), and capillarization from needle biopsies of the vastus lateralis muscle in 20 patients with chronic obstructive pulmonary disease (COPD) (FEV1 = 37 +/- 11% predicted, peak VO2 = 13 +/- 4 mL.min-1.kg-1) and nine age-matched normal subjects (peak VO2 = 33 +/- 7 mL.min-1.kg-1). The effects of endurance training on these parameters were also evaluated in 11 of the 20 patients with COPD. RESULTS: The proportion of Type I fiber was smaller in COPD than normals (34 +/- 14% vs 58 +/- 16 in normals, P < 0.0005) with a corresponding increase in Type IIb fiber (P = 0.015). The CSA of Type I, IIa, and IIab fibers was also smaller in COPD. The capillary to fiber ratio tended to be reduced in patients, but this difference did not reach statistical significance (P = 0.15). The number of capillary contact for Type I, IIa, and IIab fibers was significantly reduced in COPD compared with normal subjects (P < 0.05). When corrected for the CSA, this parameter was similar for both groups. After training, peak VO2 increased by 11% (P < 0.05), the fiber-type proportion remained unchanged, and the CSA of Type I and IIa fibers increased by 31 and 21%, respectively (P < 0.05). Although the number of capillary contact for each fiber types increased with training, the capillary to fiber ratio and the number of capillary contact for the different fiber types relative to their CSA remain unchanged. CONCLUSIONS: We conclude that in COPD, 1) the vastus lateralis muscle is characterized by a marked decrease in Type I fiber proportion, an increase in Type IIb fiber proportion, a decrease in Type I, IIa, and IIab fiber CSA and by a relatively preserved capillarization; and 2) a 12-wk training program induces a significant increase in Type I and IIa CSA.

Aged↗
PubMed1997

Protective immune responses induced by the immunization of mice with a recombinant bacteriophage displaying an epitope of the human respiratory syncytial virus.

We investigated whether a recombinant bacteriophage displaying a disease-specific protective epitope could be experimentally used as a vaccine to confer protection of immunized animals against infection. We genetically engineered a recombinant phage, fd, displaying at its surface a chimeric pIII coat protein fused to the previously identified protective epitope 173-187 from the glycoprotein G of the human respiratory syncytial virus (RSV). A selected recombinant fd phage elicited a strong immune response in mice, inducing a high level of circulating RSV-specific antibodies. Mice immunized with the recombinant phage acquired a complete resistance to RSV infection as evidenced by the lack of detectable virus particles in their lungs following intranasal challenge with live RSV. In contrast, a high level of virus particles was found in the lungs of either animals immunized with the wild-type fd phage or nonimmunized mice. To our knowledge, this is the first study to report the ability of a phage presenting an immunogenic peptide to prevent infection of immunized animals by a pathogen. This finding should facilitate the identification of pathogen-specific protective epitopes selected from random phage peptide libraries, as it is simpler and less expensive than the conventional method of synthesis and coupling of phage-specific peptide ligand sequences for immunization.

Amino Acid Sequence↗
PubMed1997

Subgroup specific protection of mice from respiratory syncytial virus infection with peptides encompassing the amino acid region 174-187 from the G glycoprotein: the role of cysteinyl residues in protection.

We identified subgroup specific protective epitopes represented by the amino acid regions 174-187 and 171-187 of the G glycoproteins from respiratory syncytial virus (RSV), subgroups A and B. Mice immunized with coupled synthetic peptides corresponding to either the region 174-187 containing a Cys186-->Ser substitution or to the native region 171-187 were completely resistant to RSV infection but only to the respective virus. The protective activities of the peptides 174-187 were dependent on the Cys186-->Ser substitution. In addition, a recombinant protein representing the region 125-203 of the A subgroup G glycoprotein expressed in Escherichia coli was capable without further treatment to completely protect animals against RSV subgroup A infection. We show that the combinations of cysteinyl residues (positions 173, 176, 182, and 186) retained within either synthetic peptides or the recombinant protein G125-203 greatly influenced their protective activities. This indicates that the region 171-187 is essential for the protection conferred by the G125-203 protein. Furthermore, our results strongly suggest that the peptides' and recombinant protein's potencies are a function of a loop-like structure which is stabilized by intramolecular disulfide linkages between Cys176-Cys182 and Cys173-Cys186. This is further supported by the observation that chemical blocking of the sulfidryl groups in synthetic peptides completely eliminated their protective activity.

Amino Acid Sequence↗
PubMed1997

Studies of the susceptibility of nude, CD4 knockout, and SCID mutant mice to the disease induced by the murine AIDS defective virus.

Murine AIDS (MAIDS) is induced by a defective retrovirus that infects lymphocyte cells of the B lineage. To determine whether functional T cells are required for the infection of B cells, T-cell-deficient mice (nude, CD4 knockout, and SCII)) were infected with helper-free stocks of the MAIDS defective virus. Infection of B cells was monitored by Northern blot analysis and in situ hybridization. The C57BL/6 nude mice contained clusters of infected B cells, but less so than did the euthymic mice. In contrast, the (C57BL/6 x BALB/c)F1 nude mice harbored more infected B cells than did their euthymic littermates when maintained in a pathogen-free environment. Clusters of infected B cells were also detected in the MAIDS virus-infected CD4-/- knockout mice despite the total absence of CD4+ T cells in these mice. However, infected cells were not detected in SCID mice (deficient in mature T and B cells) inoculated with the same virus, indicating that precursor B cells are not a target of the virus in the absence of mature CD4+ T cells. These data confirm that the primary event in the development of MAIDS is the infection of relatively mature peripheral B cells and that CD4+ T cells are required to promote the expansion of these infected B cells.

Animals↗
PubMed1997

Childhood/early adolescence-onset and adult-onset schizophrenia. Heterogeneity at the dopamine D3 receptor gene.

BACKGROUND: The dopamine D3 receptor gene (DRD3) is a meaningful candidate gene because it unifies the dopamine and the limbic hypotheses for schizophrenia. We tested for an allelic association between schizophrenia and the DRD3 Mscl alleles, hypothesising heterogeneity between childhood/early adolescence-onset schizophrenia (CO-SZ) and adult-onset schizophrenia (A-SZ). METHOD: The frequencies of the DRD3 alleles were compared between 70 DSM-III-R schizophrenics (35 CO-SZ and 35 A-SZ) and 79 controls. RESULTS: Compared with the controls, the subsample of A-SZ, but not CO-SZ, showed an over-proportion (P = 0.025) of allele 1. The association was not found in the total sample, combining the two subsamples. CONCLUSIONS: Consistently with former studies, our data suggest an aetiological heterogeneity between CO-SZ and A-SZ and a possible specificity of the excess of allele 1 to the familial form of schizophrenia and to schizophrenia with a better outcome.

Adolescent↗
PubMed1996

Transcriptional and translational expression kinetics of the early gene encoding the BICP27 protein of bovine herpesvirus type 1.

The expression kinetics of an essential trans-regulatory protein, ICP27, from herpes simplex virus type 1 correspond to that of an immediate-early gene whose expression increases rapidly upon infection and then decreases as of 7 hr postinfection. In contrast, here we report that the bovine herpesvirus type 1 (BHV-1) homolog BICP27, a 50-kDa protein, is expressed as an early gene. Both the transcript and protein accumulated gradually reaching peak levels at approximately 12 hr postinfection, after which point steady state levels were maintained up to 24 hr. Thus the expression profiles of ICP27 and BICP27 are significantly different, suggesting that they may possess different functions.

Animals↗
PubMed1996

Frequent provirus insertional mutagenesis of Notch1 in thymomas of MMTVD/myc transgenic mice suggests a collaboration of c-myc and Notch1 for oncogenesis.

The MMTVD/myc transgenic mice spontaneously develop oligoclonal CD4+CD8+ T-cell tumors. We used provirus insertional mutagenesis in these mice to identify putative collaborators of c-myc. We found that Notch1 was mutated in a high proportion (52%) of these tumors. Proviruses were inserted upstream of the exon coding for the transmembrane domain and in both transcriptional orientations. These mutations led to high expression of truncated Notch1 RNAs and proteins (86-110 kD). In addition, many Notch1-rearranged tumors showed elevated levels of full-length Notch1 transcripts, whereas nearly all showed increased levels of full-length (330-kD) or close to full-length (280-kD) Notch1 proteins. The 5' end of the truncated RNAs were determined for some tumors by use of RT-PCR and 5' RACE techniques. Depending on the orientation of the proviruses, viral LTR or cryptic promoters appeared to be utilized, and coding potential began in most cases in the transmembrane domain. Pulse-chase experiments revealed that the 330-kD Notch1 proteins were processed into 110- and 280-kD cleavage products. These results suggest that Notch1 can be a frequent collaborator of c-myc for oncogenesis. Furthermore, our data indicate that Notch1 alleles mutated by provirus insertion can lead to increased expression of truncated and full-length (330/280-kD) Notch1 proteins, both being produced in a cleaved and uncleaved form.

Animals↗
PubMed1996

A vibrational spectroscopic study of the metastable form of associated polyinosinic acid.

We have studied by Raman and ir spectroscopy the metastable complex formed by the self-association of polyinosinic acid in aqueous solution. The complex is easily prepared by quickly cooling to ca. 0 degrees C a warm solution of the polyribonucleotide to which a small amount of rubidium salt has been added. Upon heating, this metastable form melts cooperatively near 13 degrees C, well below the dissociation temperature of a stable four-stranded complex, which occurs at 47 degrees C in the same conditions. The presence of several components in the stretching-mode region of the carbonyl groups in the vibrational spectra of the metastable complex suggests that it also has a parallel four-stranded structure. The difference in structure between the two forms is believed to be caused by the presence of fewer metal ions in the central channel of the metastable complex, in agreement with conclusions reached in previous investigations. The Raman spectra further show that the ribose units in the metastable form have a C3'-endo conformation, in contrast with the stable form, for which we have previously suggested a mixed C2'-endo/C3'-endo conformation.

Drug Stability↗
PubMed1996

The bovine herpesvirus type 1 major tegument protein VP8 expressed in recombinant vaccinia virus does not induce significant immunity in mice.

We previously reported the characterization of the gene encoding the bovine herpesvirus type 1 (BHV-1) major tegument protein VP8. With the aim of defining the immunological properties of this protein, we constructed a recombinant vaccinia virus (VV-VP8) in which expression of the VP8 gene was regulated by the P7.5 early/late promoter. Since the sequence of the VP8 gene contained a TTTTTNT motif known to serve as a transcription termination signal of vaccinia virus genes of the early class, a second recombinant (VV-VP8-Mut) in which this signal was modified by site-directed mutagenesis was created. Characterization of the recombinant viruses revealed that truncated VP8 mRNA and protein (69 kDa) were synthesized in VV-VP8 infected cells, whereas cells infected with VV-VP8-Mut produced a protein which was undistinguishable from that of the BHV-1 encoded protein (92-94 kDa). Immunization of BALB/c mice (H-2d) with VV-VP8-Mut induced a low VP8-specific antibody response whereas no specific response was induced in VV-VP8 inoculated mice. The low humoral response elicited was similar in C57BL/6 (H-2b) and C3H (H-2k) mice. Furthermore, immunization of mice with VV-VP8-Mut did not induce a BHV-1-specific lymphoproliferation in the three mice strains examined. Our results contrast with a recent study showing that immunization of calves with purified VP8 stimulated both T cell proliferation and antibody production.

Animals↗
PubMed1996

Gene contents in a 31-kb segment at the left genome end of bovine herpesvirus-1.

We report the nucleotide sequence of a 31-kb segment at the left genome end of bovine herpesvirus-1 (BHV-1) and show that it comprises 19 different open reading frames (ORFs), including seven which have been described previously (circ, dUTPase, UL49.5, alpha TIF, VP8, glycoprotein C, and ribonucleotide reductase small subunit). The new sequence resulted in a correction at the C-terminus of glycoprotein C. All 19 ORFs exhibited strong amino acid sequence homology to the gene products of other alphaherpesviruses. The BHV-1 ORFs were arranged colinearly with the prototype sequence of herpes simplex virus 1 (HSV-1) in the range of the UL54 to UL37 genes. No BHV-1 homologs of the HSV-1 UL56, UL55, and UL45 genes were identified. The BHV-1 circ gene was the only gene without a HSV-1 counterpart. The additional ORFs 1 and 2 found at the left genome end of equine herpesvirus-1 (EHV-1) were absent in BHV-1. Among the newly sequenced BHV-1 ORFs are homologs of ICP27 (UL54), glycoprotein K (UL53), helicase-primase (UL52), DNA polymerase accessory protein (UL42), ribonucleotide reductase large subunit (UL39), and several virion proteins (UL49, UL46, UL43, UL41, UL38, UL37), most of which are strongly conserved in all herpesviruses. The possible functions of the proteins encoded within the sequenced region are assessed and features found are discussed.

Amino Acid Sequence↗
PubMed1996

Evidence that the murine AIDS defective virus does not encode a superantigen.

The T-cell receptor repertoire was analyzed in C57BL/6 mice upon infection with helper-free stocks of the pathogenic murine AIDS (MAIDS) defective virus in order to demonstrate if, as previously reported, this virus encodes a superantigen. A polyclonal T-cell stimulation involving T cells expressing multiple V beta subsets occurred within the first week of infection, while late in the disease we could note only a 50% deletion of V beta 5 CD8+ cells. Transfection of the MAIDS virus genomic DNA into fibroblasts and B cells expressing major histocompatibility complex class II molecules failed to show any stimulation of cells expressing the specific V beta (V beta 5) previously reported to respond to MAIDS virus-infected cells. In addition, mice lacking V beta 5 cells did not show any significant decrease in susceptibility to the disease compared with mice expressing V beta 5 and bred on the same genetic background. Our in vivo and in vitro results fail to demonstrate a role for a superantigen encoded by the MAIDS defective viral genome in the pathogenesis of MAIDS.

Animals↗