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Biomedical subjects

S Bélanger

Publications and source records attributed to S Bélanger.

17 recordsLinked to original sources
PubMed1997

The effects of tracheal occlusion and release on type II pneumocytes in fetal lambs.

UNLABELLED: Fetal tracheal occlusion (TO) has been shown to lead to lung hyperplasia in various animal models, and this procedure has already been carried out in human fetuses with congenital diaphragmatic hernia (CDH). However, the authors previously showed that TO caused a decrease in type II pneumocytes. PURPOSE: The aim of this study is to examine the effects of TO and release on type II pneumocytes. METHOD: To was carried out with a Swan Ganz or Fogarty catheter in fetal sheep at 116 to 118 days of gestation. TO was maintained for 2 weeks followed by deflation of the balloon for 1 week before delivery, in group 1; in group 2, TO was maintained for 19 days and released 2 days before delivery. Group 3 consisted of previously reported animals who had TO maintained until birth. Unoperated twins served as controls. All specimens were analyzed using the surfactant protein C (SP-C) mRNA as a specific marker for type II pneumocytes. We used Northern Blot and in situ hybridization techniques to quantify total SP-C and the density of type II cells. Electron microscopy (EM) was also used to evaluate and quantitate type II cells. RESULTS: TO resulted in significant lung growth in all groups. In situ hybridization and Northern Blot analysis showed that there was a complete recovery of type II cells in group 1 versus controls. Quantitative EM analysis confirmed these findings. In group 2 the number of type II cells was decreased but there was an increase in SP-C content per type II cell versus group 3. CONCLUSION: Lung growth after TO appears to occur at the expense of type II cell differentiation. This effect is reversible with the release of TO before birth in this animal model.

Airway Obstruction↗
PubMed1997

Influence of bilirubin on the antioxidant capacity of plasma in newborn infants.

In vitro, bilirubin is a strong antioxidant, but in vivo its capacity to act as a scavenger of toxic oxygen radicals remains poorly documented. The aim of this study was to evaluate of bilirubin had antioxidant properties in jaundiced infants. The antioxidant capacity of neonatal plasma was measured in Trolox equivalents (TEAC, mmol/l) and correlated in vitro with plasma bilirubin concentrations (r2 = 0.99). Plasma TEAC was compared before and after exchange transfusions for neonatal hyperbilirubinemia (250-435 mumol/l). The antioxidant properties of the paired blood samples before and after exchange transfusions (TEAC: 1.67 +/- 0.12 vs. 1.37 +/- 0.09 mmol/l, n = 11) varied in proportion to the serum bilirubin levels. The changes in other antioxidants were not large enough to account for the magnitude of change in antioxidant capacity. Therefore, in vivo, the plasma antioxidant capacity of jaundiced newborn infants is related to the level of bilirubin.

Analysis of Variance↗
PubMed1997

Deleterious effect of tracheal obstruction on type II pneumocytes in fetal sheep.

It was previously shown that tracheal obstruction accelerated fetal lung growth and eventually reversed the pulmonary hypoplasia in experimental diaphragmatic hernia. We have successfully developed a reversible tracheal obstruction technique in fetal sheep using balloon occlusion and showed that 3 wk of obstruction induced significant lung growth of the same magnitude as the tracheal ligation. The purpose of this study was to examine the effects of 1 and 3 wk of tracheal occlusion on the alveolar cell population with specific attention to the type II pneumocytes. We first showed that 1 wk of occlusion induced a significant increase in lung weight and in alveolar surface area. We then used the surfactant protein C (SP-C) mRNA as a specific marker of differentiated type II pneumocytes. Total RNA was isolated from fetal sheep lung with or without tracheal occlusion, and Northern blots were hybridized with a cDNA probe specific for the sheep SP-C. The results show a dramatic decrease in SP-C mRNA expression (8.8-fold, p < 0.01). In situ hybridization showed a marked decrease in the density of cells expressing SP-C, as well as the amount of SP-C mRNA expressed by the cells. The effect was present as early as 1 wk of occlusion. The sparseness of type II pneumocytes was further confirmed by electron microscopy. We thus conclude that tracheal obstruction causes a profound decrease in the number of type II pneumocytes in the lungs. Given the crucial role of type II pneumocytes in surfactant production, we could speculate that, if tracheal occlusion is able to accelerate lung growth, the final product is probably surfactant-deficient.

Airway Obstruction↗
PubMed1997

Admixture of a multivitamin preparation to parenteral nutrition: the major contributor to in vitro generation of peroxides.

BACKGROUND: Peroxides have been reported to contaminate lipid emulsions and amino acid solutions used in total parenteral nutrition (TPN). This is particularly disturbing in newborn infants who are prone to several diseases related to immature defense mechanisms against oxidative challenges. It is not clear whether the antioxidants in multivitamins help protect parenteral nutrients against the hazards of oxidation. OBJECTIVE: To evaluate the role of a multivitamin preparation (MVI) on the actual peroxide load received by patients on TPN. METHODOLOGY: The generation of peroxides in parenteral nutrition was tested first using test solutions. We compared the relative contribution of commercially available amino acid solutions, a lipid emulsion, and MVI on the level of peroxides in clinically relevant TPN solutions. Second, we measured the level of peroxides actually infused at the bedside. In both circumstances, the effects of time and light exposure were isolated. The level of peroxides was determined by a colorimetric technique and expressed as microM equivalents tert-butyl hydroperoxide (microM = TBH). RESULTS: Even when protected from light, the addition of MVI produced a 10-fold increase in peroxides (mean +/- SEM, n = 3, 19 +/- 4 to 189 +/- 8 microM = TBH at 4 h) in the fat-free TPN solution and a fourfold increase (64 +/- 6 to 244 +/- 8 microM = TBH at 4 h) in the lipid-containing TPN solution. A dose-response relationship was found between the concentration of MVI and peroxide levels. The effect of light was the strongest in the presence of multivitamins. The amino acid solutions had a relative inhibitory effect on the generation of peroxides by MVI, which varied (from 54 +/- 1% to 72 +/- 1%) all according to the amino acid blend. In parenterally fed premature infants, protecting the intravenous set from light decreased the load of infused peroxides (146 +/- 15 vs 215 +/- 24 microM = TBH). CONCLUSIONS: The lipid emulsion had a significant but minor additive effect compared with the multivitamin preparation, which was the major contributor to the generation of peroxides. Protection from photooxidation is not sufficient to prevent peroxidation of TPN solutions. Contrary to what one would expect, increasing the concentration of MVI will lead to a greater generation of peroxides, suggesting that the essential antioxidants in MVI do not have antiperoxide properties.

Amino Acids↗
PubMed1996

Comparison of effects of 95% and 90% oxygen saturations in respiratory distress syndrome.

AIMS: To determine if decreasing arterial blood saturation from 95% to 90% could cause vasoconstriction of the pulmonary vasculature and dilatation of a patent ductus arteriosus in preterm newborn infants with respiratory distress syndrome (RDS). METHODS: Doppler echocardiographic studies were compared at 95% and 90% pulse oxygen saturation (SpO2) in 13 preterm infants aged 61.7 (4.3) hours with RDS and Doppler echocardiographic evidence of tricuspid regurgitation. RESULTS: The mean (SD)Doppler echocardiographic indices determined at 95% were heart rate (146 (3.60) beats per minute), acceleration time of the velocity wave forms of the pulmonary artery (PAAT) (51.8 (2.5) milliseconds), ratio of PAAT to right ventricular ejection time (ET) (0.26 (0.02)), diameter of the ductus arteriosus (2.6 (0.6) mm), pulmonary blood flow (0.33 (0.03) l/minute) and the left ventricular shortening fraction (SF)(0.4 (0.02)%). The ascending aorta flow velocity wave form was used for the calculation of pulmonary blood flow. The right ventricular to right atrial systolic pressure gradient calculated using the peak velocity of the tricuspid regurgitation jet was 26.7 (7.4) mm Hg. CONCLUSIONS: A decrease from 95% to 90% SpO2 did not have any effect on the pulmonary circulatory haemodynamics nor the ductus arteriosus.

Carbon Dioxide↗
PubMed1996

[Mental health deterioration in workers exposed to styrene].

Emotional instability which might be an early symptom of more severe disorders, is one of the first manifestations of chronic exposure to organic solvents. The present study measures the association between exposure to styrene and mood states of active workers. A total of 128 workers (85% of the total population) from 3 factories where styrene is used, participated on a voluntary basis. They filled out the following self-administered questionnaires: Profile of Mood States (POMS), Psychiatric Symptom Index and Well-being Index. The results indicate a significant relationship between post work-shift urinary mandelic acid (biological indicator of styrene exposure) and the scores obtained on the POMS scales of tension-anxiety (Spearman's rank correlation rho = 0.30; p < 0.01), anger-hostility (rho = 0.29; p < 0.01), fatigue-inertie (rho = 0.34; p < 0.01), and confusion-bewilderment (rho = 0.23; p = 0.04), as well as the Psychological Distress Index (rho = 0.30; p < 0.01). All scores were adjusted for the effects of 4 potentially confounding variables: age, schooling, alcohol and cigarette consumption. These indicators of mood states do not constitute a diagnosis of mental disease but reveal progressive deterioration of well being associated with neurotoxic exposure in the workplace.

Adult↗
PubMed1995

On the role of extraretinal signals for saccade generation.

We investigated the accuracy of sequential saccadic eye movements, executed without visual feed-back. We found evidence that the final error of one saccade is corrected during the next, which supports the existence of extraretinal inputs to the saccadic generator. The corrections, however, were incomplete, which suggests that extraretinal signals are only partially effective.

Eye Movements↗
PubMed1995

Influence of energy substrates on respiratory gas exchange during conventional mechanical ventilation of preterm infants.

OBJECTIVE: The purpose of this study was to determine the optimal parenteral feeding regimen for infants with compromised respiratory function. METHODS: We studied the influence of varying the source of energy on respiratory gas exchange in 10 infants who were supported by mechanical ventilation and who received intravenous feedings. Two isoenergetic parenteral regimens were infused consecutively; the level of fat intake was varied inversely with that of glucose. Under similar ventilator settings, transcutaneous partial pressures of oxygen and carbon dioxide, as well as indirect calorimetry were measured during each regimen. RESULTS: Despite the higher carbon dioxide production during the glucose-rich regimen (8.9 +/- 0.7 vs 7.9 +/- 0.4 ml/kg per minute, p < 0.05 by analysis of variance), transcutaneous partial pressure of carbon dioxide remained unaffected, suggesting ventilatory compensation as documented by the increased (p < 0.002) alveolar ventilation. This was not associated with a detectable rise in oxygen consumption, but with a significant change in partial pressure of oxygen (77 +/- 5 vs 66 +/- 3 mm Hg, p < 0.05). CONCLUSIONS: Ventilator-dependent infants with early and mild bronchopulmonary dysplasia, who receive intravenous feedings of a moderate load of glucose-based energy, can compensate for enhanced carbon dioxide production by increasing their respiratory drive, with a beneficial effect on oxygenation compared with that observed when energy is derived from lipid-based solutions.

Analysis of Variance↗
PubMed1995

Visual dysfunction among styrene-exposed workers.

OBJECTIVES: The present study was undertaken to examine the relation between visual functions and occupational exposure to styrene. METHODS: A total of 128 workers (85% of the total population), from three glass-reinforced plastics plants in Canada, agreed to participate in the study. Environmental and biological measures were made on the day(s) prior to the assessment of near visual acuity (National Optical Visual Chart), chromatic discrimination (Lanthony D-15 desaturated panel), and near contrast sensitivity (Vistech 6000). The analyses were performed on 81 workers with near visual acuity of at least 1 min of arc at 0.5 m. RESULTS: The subjects were relatively young [29 (SD 8) years], with little seniority [5 (SD 4) years]. Styrene exposure for 8 h ranged from 6 to 937 (first quartile 21 mg.m-3, third quartile 303 mg.m-3), depending on the job site. The end-shift concentrations of urinary mandelic acid ranged from nondetectable to 1.90 mmol.mmol creatinine-1. Significant positive relations were found between the internal and external styrene exposure measurements and color vision loss adjusted for age, alcohol consumption, and seniority in a multiple regression analysis. The multiple regression analysis is also showed that the end-shift concentration of urinary mandelic acid was inversely related to contrast sensitivity at 6 and 12 cycles.degree-1. Logistic multiple regression models indicated that the end-shift concentration of urinary mandelic acid was related to the prevalences of blurred vision, tearing, and eye irritation. CONCLUSIONS: These findings suggest that there is a positive relation between styrene exposure and early color and contrast vision dysfunction.

Adult↗
PubMed1994

Nervous system dysfunction among workers with long-term exposure to manganese.

Neurological disorders, bearing many similarities to Parkinson's disease, have been associated with environmental and occupational exposure to manganese (Mn). To document early nervous system dysfunction associated with long-term exposure to Mn, a battery of neurofunctional tests was administered to workers employed in Mn alloy production. Study participation was 95% (n = 115). A matched pair design was used; actively working men, with no history of workplace exposure to neurotoxins, were recruited from the region as referents. Matching was done on the variables: age (+/- 3 years), educational level (+/- 2 years), smoking status, and number of children. Stationary environmental sampling indicated that Mn levels varied widely (geometric means: Mn dust, 0.89 mg/m3; respirable Mn, 0.04 mg/m3). The alloy workers had significantly higher levels of whole blood Mn (geometric mean: 1.03 microgram/100 ml vs 0.68 microgram/100 ml); no differences were observed for urinary Mn. Univariate analysis (paired t test, Signed Rank and McNemar) and multivariate analysis of variance (Hotelling-Lawley statistic) revealed that the pairs differed on symptom reporting, emotional state, motor functions, cognitive flexibility, and olfactory perception threshold; verbal fluency, basic mathematics, reading capability, and attentional capacity were similar. These findings are consistent with current knowledge on brain Mn activity and suggest that manifestations of early manganism can be observed in well designed population studies, using sensitive testing methods.

Adult↗
PubMed1994

Diadochokinesimetry: a study of patients with Parkinson's disease and manganese exposed workers.

Diadochokinesia, the ability to perform rapid alternating movements is often impaired in patients with extrapyramidal disease. It is a common sign among patients with Parkinsonism or manganism. In the present study we compare patients with Parkinson's disease (n = 11), workers formerly exposed to manganese (n = 10) and control subjects (n = 11) performing rapid alternating hand movements for 5 s under four conditions repeated twice (natural cadence and maximal speed with one or two hands). Data recorded using a diadochokinesimeter built in our laboratory and connected to a 486/33 microcomputer were digitized in real time while subjects rotated back and forth hand held foam spheres connected to flexible rods articulated with optical encoders. Significant differences were found between control subjects and patients with Parkinson's disease, but not with manganese exposed workers, in most variables examined. However, trajectory length (a combination of movement amplitude and velocity) indicated that manganese exposed workers and patients with Parkinson's disease were significantly different from the controls in functional asymmetries between right and left hand. In addition, workers and patients tend to have marked differences between the performance of right and left hands. Improved quantitative measurement of rapid alternating movements may prove to be an important tool in early and differential diagnosis of Parkinson's disease and manganese exposure.

Humans↗
PubMed1993

Parental and patient perceptions about encopresis and its treatment.

Treatment of encopresis in childhood is often a long and trying process. Children followed for secondary encopresis in a multidisciplinary clinic between 1984 and 1989 were sent a parent/child mail questionnaire seeking information on their understanding of encopresis as well as their opinions on current treatment modalities. Twenty-eight families responded (20 boys and 8 girls), the child's mean age was 9.8 years, and the mean time elapsed after diagnosis was 3.5 years. Parents and children reported that intestinal dysfunction (53%) and painful defecation (46%) were the most important causes of their encopresis. Treatment modalities including enemas were well accepted by both parents and children, with parents considering dietary changes the most useful treatment modality (p < .01). Children reported that regular "toilet routine" was the most helpful in reestablishing continence. Despite good comprehension of the problem and acceptance of the treatment modalities, the complete recovery rate after 3.5 years was only 35.7%, with no differences noted between responders and nonresponders. Encopresis is a chronic condition that persists in a significant proportion of patients, despite adequate patient and parental knowledge and patient acceptance of treatment.

Attitude to Health↗
PubMed1988

Chromal focus of acquired chromatic discrimination loss and solvent exposure among printshop workers.

Acquired dyschromatopsia has been associated with exposure to organic solvents. However, the chromal focus of the loss may be indicative of its gravity. According to Kollner's rule, blue-yellow loss reflects changes in external retinal layers, while red-green loss appears to be indicative of internal retinal or optic nerve damage. The objective of the present study was to examine chromatic discrimination capacity of 30 printshop workers exposed to organic solvent mixtures, and of a non-exposed reference group. Colour vision was assessed with a colour arrangement test designed to detect acquired dyschromatopsia, the Lanthony D-15 desaturated panel. Quantitative analysis, using Bowman's colour confusion index, revealed significantly higher scores indicative of colour vision loss among the exposed workers as compared to the non-exposed. Analysis of covariance, with age as co-variate, showed colour confusion index to be significantly associated with job category. Similarly, qualitative analysis showed that the exposed workers presented a significantly higher prevalence of acquired dyschromatopsia as compared to the non-exposed group. However, analysis of the type of chromatic discrimination loss showed that among the nonexposed persons, dyschromatopsia was localized only in the blue-yellow range, while for 35% of the dyschromatopic-exposed persons, red-green loss as well as blue-yellow loss were present. Three-dimensional chi 2-analysis showed that the complex pattern of dyschromatopsia was not related to age, but to job category. These findings suggest that the type of dyschromatopsia, reflecting the gravity of neural alterations, may be a function of exposure level and/or the ophthalmotoxic properties of the particular solvents used.

Adult↗
PubMedDate not supplied

Pilot study of peripheral markers of catecholaminergic systems among workers occupationally exposed to toluene.

In a pilot study, serum dopamine beta-hydroxylase (DBH), platelets monoamine oxidase type B (MAO B) activities and basal plasma prolactin (PRL) were measured, among 10 workers occupationally exposed to toluene and 10 control subjects, preceding and immediately following vacation. Six exposed subjects were employed in an adhesive tape making industry and 4 in a paint making industry. Their median basal levels of urinary hippuric acid were 0.44 mmole/mmole creatinine (cr) (range 0.23-1.97) and 0.18 mmole/mmole cr (range 0.15-0.19) respectively, the second to last morning of the work week, preceding vacation. The level of basal urinary hippuric acid among the control group was 0.26 mmole/mmole cr (range 0.03-0.38). The workers from the adhesive tape plant reported a significantly higher number of symptoms experienced frequently (Kruskal, Wallis, p < 0.05). On a group basis, serum DBH was lowest among the workers from the adhesive tape plant, who had the highest levels of basal urinary hippuric acid. In addition, a negative relation was observed between hippuric acid and serum DBH, preceding and following vacation (Rho = -0.46, p = 0.05; Rho = -0.51, p = 0.03). The observed changes in serum DBH activity are consistent with its decrease in human, following long-term exposure to styrene, another aromatic hydrocarbon. The findings of this pilot study, on a limited number of individuals suggest that DBH may be a sensitive peripheral bioindicator. Further studies of larger groups should be done to confirm the decrease in serum DBH activity with toluene exposure and explore whether this alteration is related to the neurotoxic impairments associated with exposure.

Adult↗
PubMedDate not supplied

Surveillance of early neurotoxic dysfunction.

Surveillance of early neurotoxic alterations was undertaken in 3 reinforced plastics plants, with a view to preventive intervention. Using a longitudinal study design, exposure parameters (environmental styrene in the respiratory zone of each worker and end-shift mandelic acid (MA)) and neurobehavioral performance (Neurobehavioral Core Test Battery and Field Assessment: Sensory Tests), were assessed at time zero (T0); recommendations were made to reduce exposure at jobsites with the highest risk. Reassessment was made two years later (T2). Complete exposure data was available for 118 workers at T0; 75 were still employed at T2; of these, 57 (76%) returned for testing. Those who returned had more seniority (p < 0.001) and higher MA (p < 0.01) and styrene (p < 0.05) levels at T0 than the others. Analyses, performed on the T0-T2 differences, showed improvement in exposure parameters in Plant 3, where lower levels were observed at T2 for styrene (p < 0.05) and MA (p < 0.001). workers in Plant 3 (n = 29) performed better (p < 0.05) at T2 for short term memory, perceptuo-motor speed, motor precision and manual dexterity; they reported more vigor (p < 0.05) and less anger (p = 0.07). This was not the case for the workers from the other plants. Generally, the T0-T2 difference in MA was associated (Spearman's Rho) with differences in color vision (p < 0.001), simple reaction time (mean and standard deviation), digit span forward, tension, fatigue and the number of symptoms (p < 0.05); aiming precision showed a similar tendency (p < 0.10). These findings suggest that group surveillance of early nervous system changes for jobs with exposure to neurotoxins, using a sensitive neurofunctional test battery, may be useful for preventive intervention.

Adult↗