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M Bélanger

Publications and source records attributed to M Bélanger.

At least 19 recordsLinked to original sources
PubMed2001

The gene encoding the major viral structural protein stimulates recombination in polyomavirus DNA.

RmI is a chimeric DNA molecule consisting of a polyoma genome in which a partly duplicated VP1-coding region brackets an insert of murine DNA (Ins); when transfected into mouse cells, RmI recombines intramolecularly to yield infectious, unit-length, polyoma DNA. We report here that RmI encodes a polypeptide of 337 amino acids (designated VmP1) which includes the N-terminal 328 amino acids of VP1 and 9 amino acids specified by Ins. Mutating the VmP1-coding sequence strongly reduces the ability of RmI to yield polyoma DNA. In contrast, mutating the portion of the VP1-coding sequence which is not part of the VmP1-coding sequence has little or no impact on the ability of RmI to yield polyoma DNA, even though it renders such DNA noninfectious. Thus, release of polyoma DNA from RmI involves a function of VP1 distinct from that ensuring virus assembly and propagation; since VP1 can arise only after recombination has occurred, VmP1, but not VP1, could carry such a function. We suggest that VmP1 acts in concert with VP2, which we have already reported to stimulate recombination in RmI.

Amino Acid Sequence↗
PubMed2001

Effects of oxygen on lower limb blood flow and O2 uptake during exercise in COPD.

PURPOSE: To quantify the effects of acute oxygen supplementation on lower limb blood flow (QLEG), O2 delivery (QO2LEG), and O2 uptake (VO2LEG) during exercise and to determine whether the metabolic capacity of the lower limb is exhausted at peak exercise during room air breathing in patients with COPD. METHODS: Oxygen (FIO2 = 0.75) and air were randomly administered to 14 patients with COPD (FEV1: 35 +/- 2% pred, mean +/- SEM) during two symptom-limited incremental cycle exercise tests. Before exercise, a cannula was installed in a radial artery and a thermodilution catheter inserted in the right femoral vein. At each exercise step, five-breath averages of respiratory rate, tidal volume, and ventilation (VE), dyspnea and leg fatigue scores, arterial and venous blood gases, and QLEG were obtained. From these measurements, VO2LEG was calculated. RESULTS: Peak exercise capacity increased from 46 +/- 3 W in room air to 59 +/- 5 W when supplemental oxygen was used (P < 0.001). QLEG, QO2LEG, and VO2LEG were greater at peak exercise with O2 than with air (P < 0.05). During submaximal exercise, dyspnea score and VE were significantly reduced with O2 (P < 0.05), whereas QLEG, VO2LEG, and leg fatigue were similar under both experimental conditions. The improvement in peak exercise work rate correlated with the increase in peak QO2LEG (r = 0.66, P < 0.01), peak VO2LEG (r = 0.53, P < 0.05), and reduction in dyspnea at iso-exercise intensity (r = 0.56, P < 0.05). CONCLUSION: The improvement in peak exercise capacity with oxygen supplementation could be explained by the reduction in dyspnea at submaximal exercise and the increases in QO2LEG and VO2LEG, which enabled the exercising muscles to perform more external work. These data indicate that the metabolic capacity of the lower limb muscles was not exhausted at peak exercise during room air breathing in these patients with COPD.

Aged↗
PubMed2001

Recombinant major antigenic protein 2 of Ehrlichia canis: a potential diagnostic tool.

The major antigenic protein 2 (MAP2) of Ehrlichia canis was cloned and expressed. The recombinant protein was characterized and tested in an enzyme-linked immunosorbent assay (ELISA) format for potential application in the serodiagnosis of canine monocytic ehrlichiosis. The recombinant protein, which contained a C-terminal polyhistidine tag, had a molecular mass of approximately 26 kDa. The antigen was clearly identified by Western immunoblotting using antihistidine antibody and immune serum from an experimentally infected dog. The recombinant MAP2 (rMAP2) was tested in an ELISA format using 141 serum samples from E. canis immunofluorescent antibody (IFA)-positive and IFA-negative dogs. Fifty-five of the serum samples were from dogs experimentally or naturally infected with E. canis and were previously demonstrated to contain antibodies reactive with E. canis by indirect immunofluorescence assays. The remaining 86 samples, 33 of which were from dogs infected with microorganisms other than E. canis, were seronegative. All of the samples from experimentally infected animals and 36 of the 37 samples from naturally infected animals were found to contain antibodies against rMAP2 of E. canis in the ELISA. Only 3 of 53 IFA-negative samples tested positive on the rMAP2 ELISA. There was 100% agreement among IFA-positive samples from experimentally infected animals, 97.3% agreement among IFA-positive samples from naturally infected animals, and 94.3% agreement among IFA-negative samples, resulting in a 97.2% overall agreement between the two assays. These data suggest that rMAP2 of E. canis could be used as a recombinant test antigen for the serodiagnosis of canine monocytic ehrlichiosis.

Animals↗
PubMed2000

WbpO, a UDP-N-acetyl-D-galactosamine dehydrogenase from Pseudomonas aeruginosa serotype O6.

WbpO is associated with B-band lipopolysaccharide biosynthesis in Pseudomonas aeruginosa serotype O6. This protein is thought to catalyze the enzymatic conversion of UDP-N-acetyl-d-galactosamine (UDP-GalNAc) to UDP-N-acetyl-d-galactosaminuronic acid (UDP-GalNAcA). WbpO was overexpressed with a C-terminal hexahistidine tag. The soluble form of expressed WbpO (WbpO(Sol)) exhibited a secondary structure with 29.2% alpha-helix and 20.1% beta-strand. However, no enzymatic activity could be detected using either high performance anion exchange chromatography or capillary electrophoresis-mass spectrometry analysis. An insoluble form of expressed WbpO was purified in the presence of guanidine hydrochloride by immobilized metal ion affinity chromatography. After refolding, this preparation of WbpO (designated as WbpO(Rf)) exhibited stable secondary structure at pH 7.5 to 8.2, and it was enzymatically active. Capillary electrophoresis-mass spectrometry and tandem mass spectrometry analysis showed that WbpO(Rf) catalyzed the conversion of UDP-GalNAc to UDP-GalNAcA. 26 and 22% of the substrate could be converted to UDP-GalNAcA in the presence of NAD(+) and NADP(+) as the cofactors, respectively. The K(m) values of WbpO(Rf) for UDP-GalNAc, NAD(+), and NADP(+) were 7.79, 0.65, and 0.44 mm, respectively. WbpO(Rf) can also catalyze the conversion of UDP-GlcNAc to UDP-GlcNAcA. In conclusion, this is the first report of the overexpression, purification, and biochemical characterization of an NAD(+)/NADP(+)-dependent UDP-GalNAc dehydrogenase. Our results also complete the biosynthetic pathway for GalNAcA that is part of the O-antigen of P. aeruginosa serotype O6 lipopolysaccharide.

Amino Acid Sequence↗
PubMed2000

Electrical stimulation: can it increase muscle strength and reverse osteopenia in spinal cord injured individuals?

OBJECTIVE: To study the extent to which atrophy of muscle and progressive weakening of the long bones after spinal cord injury (SCI) can be reversed by functional electrical stimulation (FES) and resistance training. DESIGN: A within-subject, contralateral limb, and matching design. SETTING: Research laboratories in university settings. PARTICIPANTS: Fourteen patients with SCI (C5 to T5) and 14 control subjects volunteered for this study. INTERVENTIONS: The left quadriceps were stimulated to contract against an isokinetic load (resisted) while the right quadriceps contracted against gravity (unresisted) for 1 hour a day, 5 days a week, for 24 weeks. MAIN OUTCOME MEASURES: Bone mineral density (BMD) of the distal femur, proximal tibia, and mid-tibia obtained by dual energy x-ray absorptiometry, and torque (strength). RESULTS: Initially, the BMD of SCI subjects was lower than that of controls. After training, the distal femur and proximal tibia had recovered nearly 30% of the bone lost, compared with the controls. There was no difference in the mid-tibia or between the sides at any level. There was a large strength gain, with the rate of increase being substantially greater on the resisted side. CONCLUSION: Osteopenia of the distal femur and proximal tibia and the loss of strength of the quadriceps can be partly reversed by regular FES-assisted training.

Adult↗
PubMed2000

Expression of a gene encoding the major antigenic protein 2 homolog of ehrlichia chaffeensis and potential application for serodiagnosis.

The major antigenic protein 2 (MAP2) homolog of Ehrlichia chaffeensis was cloned and expressed. The recombinant protein was characterized and tested in an enzyme-linked immunosorbent assay (ELISA) format for potential application in the serodiagnosis of human monocytic ehrlichiosis. The recombinant protein, which contained a C-terminal polyhistidine tag, had a molecular mass of approximately 26 kDa. The antigen was clearly identified by Western immunoblotting using antihistidine antibody. However, immune sera failed to react with the recombinant on immunoblots when the antigen was denatured by heat or reduced using beta-mercaptoethanol. The recombinant MAP2 (rMAP2) was used in an ELISA format with 60 blinded serum samples. Twenty of the serum samples were previously demonstrated to contain antibodies reactive with E. chaffeensis by indirect immunofluorescence assays (IFAs). The remaining 40 samples were seronegative. All samples negative by IFA were also found to be negative for antibodies against the rMAP2 of E. chaffeensis by using the ELISA. Only 1 of 20 IFA-positive samples tested negative in the rMAP2 ELISA. There was 100% agreement using IFA-negative samples and 95% agreement using IFA-positive samples, resulting in a 97.5% overall agreement between the two assays. These data suggest that the rMAP2 homolog of E. chaffeensis may have potential as a test antigen for the serodiagnosis of human monocytic ehrlichiosis. To our knowledge, this recombinant is unique because it is thus far the only E. chaffeensis recombinant antigen that has been shown to work in an ELISA format.

Antigens, Bacterial↗
PubMed2000

Oxidative enzyme activities of the vastus lateralis muscle and the functional status in patients with COPD.

BACKGROUND: Enzymatic and histochemical abnormalities of the peripheral muscle may play a role in exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). A study was undertaken to measure the mitochondrial enzyme activity of the vastus lateralis muscle in patients with COPD and to evaluate the relationship between enzyme activities and functional status. METHODS: Fifty seven patients with COPD of mean (SD) age 66 (7) years with forced expiratory volume in one second (FEV(1)) 39 (15)% predicted and peak oxygen uptake (VO(2)) of 14 (4) ml/min/kg and 15 normal subjects of similar age were included in the study. Each subject performed a stepwise exercise test up to maximal capacity during which five-breath averages of VO(2) were measured. Muscle specimens were obtained by percutaneous needle biopsy of the vastus lateralis muscle and the activity of two mitochondrial enzymes (citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HADH)) was measured. The functional status of the patients was classified according to peak VO(2). RESULTS: CS and HADH activities were markedly reduced in patients with COPD compared with normal subjects (22.3 (2.7) versus 29.5 (7.3) micromol/min/g muscle (p<0.0001) and 5. 1 (2.0) versus 6.7 (1.9) micromol/min/g muscle (p<0.005), respectively). The activity of CS decreased progressively with the deterioration in the functional status while that of HADH was not related to functional status. Using a stepwise regression analysis, percentage predicted functional residual capacity (FRC), the activity of CS, oxygen desaturation during exercise, age, and inspiratory capacity (% pred) were found to be significant determinants of peak VO(2). The regression model explained 59% of the variance in peak VO(2) (p<0.0001). CONCLUSIONS: The oxidative capacity of the vastus lateralis muscle is reduced in patients with moderate to severe COPD compared with normal subjects of similar age. In these individuals the activity of CS correlated significantly with peak exercise capacity and independently of lung function impairment.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed2000

Ontogenetic changes in visual sensitivity of the parasitic salmon louse Lepeophtheirus salmonis.

The salmon louse, Lepeophtheirus salmonis, is an ectoparasitic copepod of salmonid fishes whose life cycle involves two broadly defined, free-living larval stages, the nauplius and the copepodid. After settling on a host, the copepodid goes through various transformations to become a mobile adult. We recorded swimming responses of free-swimming salmon lice at the naupliar, copepodid and adult stages to the onset (ON) and offset (OFF) of lights of varying spectral irradiance and polarization. Nauplii showed a prominent swim-up OFF response across the spectrum 352-652 nm, but no ON response. Copepodids exhibited a swim-up ON response and a passive (sinking) OFF response across the same spectral range. Adults showed active swim-up responses to both ON and OFF stimuli, although the OFF response was proportionately stronger. The spectral range of the adult ON and OFF responses was the same as that of the copepodids and slightly greater than that of the nauplii, which did not exhibit responses at 652 nm. The absolute sensitivity of copepodids under white light (approx. 10(-13) photons m(2) s(1)) was higher than that of nauplii (approx. 10(-17) photons(-1) m(2 )s, OFF response) and that of adult female lice (approx. 10(-14) photons(-1)m(2)s). This suggests that the naupliar visual system is best suited for detection of shadows (e.g. the host) under a bright light field (daylight hours), while copepodids and adults may be more specialized for host detection at crepuscular periods and during the night, when light levels are low. None of the developmental stages responded to the rotation of the plane of polarized light or exhibited any difference in directed response when polarized light was used in place of diffuse light.

Animals↗
PubMed1999

Reduction of caveolin 1 gene expression in lung carcinoma cell lines.

Caveolae are plasma membrane microdomains that have been implicated in organizing and concentrating certain signaling molecules. Caveolins, constitute the main structural proteins of caveolae. Caveolae are abundant in terminally differentiated cell types. However, caveolin-1 is down-regulated in transformed cells and may have a potential tumor suppressor activity. In the lung, caveolae are present in the endothelium, smooth muscle cells, fibroblasts as well as in type I pneumocytes. The presence of caveolae and caveolin expression in the bronchial epithelium, although probable, has not been investigated in human. We were interested to see if the bronchial epithelia express caveolins and if this expression was modified in cancer cells. We thus tested for caveolin-1 and -2 expression several bronchial epithelial primary cell lines as well as eight lung cancer cell lines and one larynx tumor cell line. Both caveolin-1 and -2 are expressed in all normal bronchial cell lines. With the exception of Calu-1 cell line, all cancer cell lines showed very low or no expression of caveolin-1 while caveolin-2 expression was similar to the one observed in normal bronchial epithelial cells.

Caveolin 1↗
PubMed1999

Treatment with interferon beta-1b improves quality of life in multiple sclerosis.

BACKGROUND: The Canadian Burden of Illness Study Group reported that the quality of life (QoL) of multiple sclerosis (MS) patients falls drastically, early in the disease. With disability progression, the physical functioning scales of the Short Form 36 (SF-36) showed further decreases in QoL. The objective of this study is to describe the QoL of MS patients treated with interferon beta-1b (IFNB-1b) and to compare it to the QoL observed in a group of patients who had not been treated with IFNB-1b. METHODS: Treated patients were prospectively recruited and were seen at their regular visit to the MS clinic. They self-completed the SF-36 questionnaire and their QoL was described and retrospectively compared to that of historical controls. RESULTS: When IFNB-1b treated patients were compared to historical control patients with the same relapsing forms of MS, the treated patients with an Expanded Disability Status Scale (EDSS) score lower than 3.0 had a significantly better QoL. This was significant for four of the eight SF-36 domains: Physical Function (+22%, p = 0.0102), Role-Physical (+100%, p = 0.0022), General Health (+27%, p = 0.0070) and Social Function (+19%, p = 0.0287). The average QoL difference was 8% in the EDSS 3.0-6.0 group and 10% in the EDSS > 6 group. CONCLUSION: Patients with relapsing forms of MS treated with IFNB-1b have better QoL than patients who are not treated, especially those with an EDSS < 3.0.

Adolescent↗
PubMed1998

Metabolic and hemodynamic responses of lower limb during exercise in patients with COPD.

Premature lactic acidosis during exercise in patients with chronic obstructive pulmonary disease (COPD) may play a role in exercise intolerance. In this study, we evaluated whether the early exercise-induced lactic acidosis in these individuals can be explained by changes in peripheral O2 delivery (O2). Measurements of leg blood flow by thermodilution and of arterial and femoral venous blood gases, pH, and lactate were obtained during a standard incremental exercise test to capacity in eight patients with severe COPD and in eight age-matched controls. No significant difference was found between the two groups in leg blood flow at rest or during exercise at the same power outputs. Blood lactate concentrations and lactate release from the lower limb were greater in COPD patients at all submaximal exercise levels (all P < 0.05). Leg D02 at a given power output was not significantly different between the two groups, and no significant correlation was found between this parameter and blood lactate concentrations. COPD patients had lower arterial and venous pH at submaximal exercise, and there was a significant positive correlation between venous pH at 40 W and the peak O2 uptake (r = 0.91, P < 0.0001). The correlation between venous pH and peak O2 uptake suggests that early muscle acidosis may be involved in early exercise termination in COPD patients. The early lactate release from the lower limb during exercise could not be accounted for by changes in peripheral O2. The present results point to skeletal muscle dysfunction as being responsible for the early onset of lactic acidosis in COPD.

Acidosis, Lactic↗
PubMed1996

Characteristics of subjects with a high frequency of emergency visits for asthma.

The determinants of frequent visits to the emergency department (ED) for asthma were evaluated in 30 patients who made 2 or more ED visits for asthma (mean, 3.1; range, 2 to 9) over a period of 1 year. They were matched for age, sex, and medication with a control group of asthmatic patients who had made no ED visits within the same period. Evaluation included measurements of expiratory flows (baseline FEV1; PEFR 4 times daily for 3 weeks), airway responsiveness to methacholine, perception of induced bronchoconstriction, and questionnaires on quality of life and knowledge of asthma and its management. In comparison with the control group, the study group showed a trend toward inferior socioeconomic status, education level, and technical abilities (eg, inhaler use). Both groups had similar baseline FEV1, reversibility of airflow obstruction, methacholine-induced changes in expiratory flows, and perception of bronchoconstriction. Diurnal variation in PEFR was slightly increased in the study group. Absenteeism from work or school was higher in the study group but quality of life score was similar to controls. Patients with frequent ED visits showed significantly lesser knowledge of asthma control criteria, as well as an overall trend toward reduced asthma management knowledge and skills. In conclusion, in addition to the previously reported undertreatment of asthma, other factors such as insufficient asthma management knowledge and skills may contribute to frequent ED visits for asthma.

Adolescent↗
PubMed1996

A comparison of treadmill locomotion in adult cats before and after spinal transection.

1. The aim of this study was to document the kinematics and the electromyographic activity recorded from several muscles during treadmill locomotion in the same cat (N = 4), before and after spinalization by using a chronic implantation method. Because identical experimental and control conditions were used, it was possible to establish similarities and differences in the timing and amplitude of the muscular activity and kinematics under the intact and spinal conditions in the same animal. The data presented in this paper were collected when the cats had fully recuperated a stable locomotor pattern, walking at a constant speed of approximately 0.4 m/s. 2. The adult spinal cats retained many of the general locomotor features and electromyographic (EMG) characteristics seen before transection. However, there were also important differences. 3. There was a reduction in the step length that was principally due to the forward placement of the paw at the onset of the stance. Similarly, there was a decrease in the step cycle duration which was attributed to a reduction of both the stance and swing phases. 4. The overall angular excursions of the hip, knee, and ankle were generally similar, although joints were sometimes more flexed at all phases of the step cycle. In contrast, the overall excursions of the metatarsophalangeal joints was much greater in all four cats after spinalization due to a paw drag during the initial portion of the swing phase that exaggerated the plantarflexion. 5. There was an increase in the EMG amplitude of the flexor muscles at two of three joints (i.e., hip, knee, and ankle) in each cat after spinalization. The change in the EMG amplitude of the extensors did not appear to be as consistent as that observed in the flexor muscles. When looking at each cat individually, the postspinalization extensor activity decreased at two of three joints in two cats, whereas the opposite was true for the other two cats. 6. There was a delay in the onset of the knee flexor (semitendinosus) activity while the ankle dorsiflexor (tibialis anterior) activity started earlier with respect to the beginning of the swing phase. The onset of hip flexors was somewhat more variable. This change in the timing of flexor activity was most probably responsible for the paw drag at the onset of the swing phase. 7. The present results reveal that despite the few differences, the spinal cord and the hindlimbs afferents are capable of generating very good locomotor patterns with almost normal kinematics and EMG characteristics.

Animals↗
PubMed1996

Locomotor capacities after complete and partial lesions of the spinal cord.

This paper first reviews some of the observations made on the locomotor capabilities of several animal species with a special emphasis on cats and including primates and man after complete spinal lesions. We show that animals can perform well-coordinated walking movements of the hindlimbs when they are placed on a treadmill belt and this locomotion is also adaptable to speed and perturbations. Cats with partial spinal lesions of the ventral and ventrolateral parts of the cord can perform voluntary quadrupedal locomotion overground or on the treadmill albeit with deficits in weight support and interlimb coordination. We also show that some drugs such as clonidine (an alpha-2 noradrenergic agonist) can be used to trigger locomotion in early-spinal cats and discuss the effects of various neurotransmitter systems on the expression of the locomotor pattern in both complete and partial spinal cats. It is concluded that a pharmacological approach could be used, in combination with other approaches, such as locomotor training and functional electrical stimulation, to improve locomotor functions after spinal cord injuries in humans.

Animals↗
PubMed1996

Pharmacokinetics of enrofloxacin in adult horses and concentration of the drug in serum, body fluids, and endometrial tissues after repeated intragastrically administered doses.

OBJECTIVE: To investigate the pharmacokinetics of enrofloxacin in adult horses. DESIGN: 2-dose oral and i.v. cross-over trial followed by multiple oral doses. ANIMALS: 8 clinically normal adult horses. PROCEDURE: Enrofloxacin was administered at dosages of 2.5 mg/kg of body weight to 4 horses and 5.0 mg/kg to 4 other horses. Each dose was given by the intragastric and i.v. routes, using a cross-over design. After the first intragastric dose, 5 additional doses were administered at 12-hour intervals. Enrofloxacin concentrations were measured in serum, synovial fluid, peritoneal fluid, urine, CSF, and endometrial tissues. RESULTS: Disposition of enrofloxacin after i.v. administration conformed to a 2-compartment model with an elimination half-life of 5.95 and 6.09 hours for the low and high dose, respectively. After the first intragastric administration, time to peak concentration was 1.0 +/- 0.35 and 1.25 +/- 0.43 hours, and the bioavailability was 57.39 +/- 8/45 and 62.52 +/- 19.65% for the low and high dose, respectively. After multiple intragastric administration, peak serum concentration (at 72 to 96 hours) was 2.62 +/- 0.61 micrograms/ml for the low dose and 5.97 +/- 1.56 micrograms/ml for the high dose. After multiple intragastric doses, synovial fluid, urine, and endometrial tissue concentrations exceeded serum concentrations. Peritoneal fluid and CSF concentrations were lower than serum concentrations. CONCLUSIONS: Computer modeling of the pharmacokinetic variables suggested that a single daily i.v. administered dose of 5.5 mg/kg, or orally administered doses of 7.5 mg/kg every 24 hours or 4.0 mg/kg every 12 hours, would be effective in horses. Additional studies are necessary to confirm the efficacy and safety of these dosages in a clinical setting.

Administration, Oral↗
PubMed1995

Screening for Down syndrome during the first and second trimesters: impact of risk estimation parameters.

OBJECTIVES: To evaluate impact of risk estimation parameters for screening for Down Syndrome during the first and second trimesters. METHODS: We prospectively examined for their performance in the prenatal prediction of trisomy 21, alphafetoprotein (AFP), unconjugated estriol (uE3), total human chorionic gonadotropin (hCG), and its free subunits (free alpha-hCG, free beta-hCG) at both the first and second trimesters, and the impact of three sets of published risk estimation parameters. A total of 14,612 pregnancies were studied. All Down syndrome specimens (12 and 11 cases for first and second trimesters, respectively) and a sample of the unaffected pregnancies were analyzed. RESULTS: The median multiple of median (MoM) for total hCG was lower in the first trimester (1.83 vs. 2.01 in the second trimester) but no loss in discriminative power was observed if the lower variability of the results in the first trimester is taken into account (interquartile range of 0.251 vs. 0.338). The choice of distribution parameters did not alter significantly the detection rates for the various combinations of markers (p > 0.05). False positive rates were affected significantly however and for the combination AFP-uE3-free beta-hCG they varied from 14.6% to 22.6% (p < 0.001). CONCLUSIONS: Our results suggest that specific distribution parameters would be necessary to account for the lower variability of the markers in the first trimester and the peculiarity of the total hCG assay we used.

Adult↗