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Biomedical subjects

D Desjardins

Publications and source records attributed to D Desjardins.

At least 19 recordsLinked to original sources
PubMed2001

Agonistic behavior in groups of limbic epileptic male rats: pattern of brain damage and moderating effects from normal rats.

Different ratios of normal male rats and male rats in which limbic seizures had been induced by a single systemic injection of lithium and pilocarpine were housed in groups of six. The group ratios ranged along the continuum from all normal rats to all experimental rats. The average numbers of episodes of boxing, biting and mounting--thrusting per rat per hour per group were recorded by direct observation (red light) for 1 h during the midscotophase. Groups that contained less than two normal rats exhibited significantly elevated amounts of agonistic (boxing, biting) behavior but not mounting behavior. Multiple regression analyses showed that combinations of neuronal loss within only two to three areas accommodated at least 50% of the variance in the numbers of these behaviors.

Agonistic Behavior↗
PubMed2001

Three year injury crash records of new licensees with suspensions or invalidity periods lasting 90 days or more.

A subset of new licensees, namely the ones with suspensions or invalidity periods of at least 90 days are studied. This subpopulation is comprised of 3,550 men and 1,295 women for whom the study file contains age, gender, licensing exam performance, and the dates all police reported crashes for the first three years after licensing. This group is compared with the complementary subpopulation of 53,069 men and 58,464 women. The average injury crash rate per year, not prorated, is 0.057 for men and 0.033 for women, about twice the rate for those without lengthy suspensions. These licensees are older, have lower success rates at licensing exams, and have a longer learning period than the others. Separate logistic-normal regression models for men and for women are estimated for the probability of a collision in a year using the available explanatory variables.

Accidents, Traffic↗
PubMed2000

Impact of diabetes on crash risks of truck-permit holders and commercial drivers.

OBJECTIVE: The U.S. and some Canadian government agencies have waived commercial license restrictions for some insulin-using diabetic drivers. However, the U.S. Federal Highway Administration is no longer giving waivers. Scientific evidence to support such regulations has been sparse. This article presents detailed analyses of crash risks for users and nonusers of insulin among diabetic truck-permit holders in Québec, Canada. RESEARCH DESIGN AND METHODS: Diabetic truck-permit holders were group-matched by age to a random sample of healthy permit holders. Data on permits, medical conditions, and crashes involving 13,453 permit holder-years in 1987-1990 were extracted from the files of the public insurer for automobile injuries in Québec. Additional health status data were obtained from the provincial public health insurer. A telephone survey was conducted to collect data on driving patterns and exposure. Risk ratios were estimated using negative binomial regression models. RESULTS: Risk ratios for crashes vary by category of diabetes. Permit holders for single-unit trucks (STs) who are diabetic without complications and not using insulin have an increased crash risk of 1.68 when compared with healthy permit holders of the same permit class. When controlling for risk exposure, commercial drivers with an ST permit and the same diabetic condition have an increased risk of 1.76. Insulin use is not associated with higher crash risk. CONCLUSIONS: The increased crash risk for the group with uncomplicated diabetes not using insulin is a new finding. The lack of consistent increases in crash risks among diabetic commercial drivers with complications or who use insulin may be a "healthy worker effect" masking the real risk, because these licensees have a lower participation rate as professional drivers.

Accidents, Traffic↗
PubMed1998

Ventricular dilation over several weeks following induction of excitotoxic (systemic lithium/pilocarpine) lesions: potential role of damage to the substantia nigra reticulata.

Time-dependent atrophy of cerebral space and enlargement of the lateral ventricles were noted in healthy rats 1 to 100 days after the induction of seizures by a single systemic injection of lithium and pilocarpine. The rate of atrophy was most strongly correlated (0.90) with the log (base 10) of the time in days. Most of the degeneration had occurred within about 20 to 30 days after the seizure-induced brain trauma. Concomitant reduction in the area of the substantia nigra reticulata was the most powerful predictor of ventricular enlargement at the level of the caudate-putamen.

Animals↗
PubMed1997

Specific IgE-dependent sensitization, atopy, and bronchial hyperresponsiveness in apprentices starting exposure to protein-derived agents.

Atopy, specific IgE sensitization, and bronchial hyperresponsiveness (BHR) were examined in a cohort of 769 apprentices starting career programs in animal health or veterinary medicine (Group 1), pastry making (Group 2), and dental hygiene (Group 3). The hypothesis were that: (1) a proportion of subjects can be "sensitized" although no significant specific occupational exposure has occurred; and (2) there is a relationship between baseline specific sensitization to work-related antigens and host characteristics. Skin tests were administered using 11 common inhalants and specific allergens, including six laboratory animal extracts, three cereal antigens, alpha-amylase, and latex. Methacholine challenge tests were performed. The prevalence of atopy was 54.4% in Group 1, 58.1% in Group 2, and 52.5% in Group 3. Skin reactivity to work-specific proteins was as follows: laboratory animal proteins, 13.8% in Group 1, 14.0% in Group 2, and 15.6% in Group 3. No subject was sensitized to alpha-amylase, whereas 1.2% in Group 1, 5% in Group 2, and 4.1% in Group 3 were sensitized to flour. Five subjects reacted to latex. BHR (PC20 < or = 8 mg/ml) was present in 17.6%, 21.2%, and 14.8% of subjects in Groups 1, 2, and 3, respectively. Specific sensitization was associated with positive skin reactions to common allergens, work-related symptoms, and BHR. These results suggest that students starting career programs with exposure to high-molecular-weight allergens have a low but substantial frequency of specific sensitization to work-related allergens that is related to atopy and BHR.

Adult↗
PubMed1996

Medical conditions and the severity of commercial motor vehicle drivers' road accidents.

In this research we studied the association between commercial motor vehicle drivers' medical conditions and crash severity. Some aspects of medical condition were considered. To our knowledge, no study has ever isolated this association. The severity of a crash was measured by the total number of victims (injured and dead). We estimated nonlinear regression models (specifically, Poisson and negative binomial) which incorporated, simultaneously, information on drivers' characteristics, crash circumstances and health status, in order to isolate the association between health status and crash severity. Our results show that crashes of truck drivers with binocular vision problems and bus drivers with hypertension are more severe than those of healthy drivers. No other medical condition considered in this study was significantly associated with crash severity. Many variables describing crash circumstances were also significant.

Accidents, Occupational↗
PubMed1995

Medical conditions, risk exposure, and truck drivers' accidents: an analysis with count data regression models.

Recent studies do not agree on the possible relationship between medical conditions and traffic safety; most of them do not control for exposure factors. This problem has become more pertinent for scientific studies because of litigation that showed that present regulations about access to driver permits might contravene human rights legislation. In our study, we estimate the effect of different medical conditions on truck drivers' distributions of accidents. Our data and our models permit simultaneous control for age; medical conditions; exposure factors measured by hours, kilometer, and qualitative factors; and other characteristics of truck drivers. Our results show that diabetic truck drivers of the permit class for straight trucks have more accidents than drivers in good health. No other studied medical condition has a significant effect on individual accident distributions. Many risk exposure variables are also significant. The effect of age is discussed in detail.

Accidents, Occupational↗
PubMed1995

Association between intermale social aggression and cellular density within the central amygdaloid nucleus in rats with lithium/pilocarpine-induced seizures.

Aggressive behaviors (numbers of bites/hour) within groups (ns = 8) of normal rats and rats in which seizures had been induced by a single systemic injection of lithium/pilocarpine were observed for 11 successive, 1-hr, periods. Mean numbers of neurons and glial cells were counted for 10 different nuclei of the amygdala for 16 different brains (8 control; 8 seizure). Although there was no significant difference found between rats with chronically induced seizures and controls for the numbers of neurons per area within the central medial amygdaloid nucleus, the neuronal density was correlated significantly (.92) with mean numbers of bites per hour for the chronically epileptic group only. The hypothesis that seizure-induced damage within proximal amygdaloid nuclei disinhibits the central nucleus and encourages aggression was supported.

Aggression↗
PubMed1993

Exposure for different license categories through a phone survey: validity and feasibility studies.

This paper presents: (i) an operational definition of risk exposure, (ii) a questionnaire developed to measure exposure, (iii) validity studies of estimates of the distance traveled and time spent driving for different permit holder categories, and (iv) a feasibility study for a telephone survey on exposure. Results show that long-distance truck drivers from one company studied estimated accurately their distance driven on the last worked day; Montreal Urban Community Transport Commission bus drivers estimated well their time behind the wheel; while a convenience sample of private car drivers (coworkers and friends) estimated well their previous week distance and time on the road. Phone surveys appear to be an efficient and cost-effective method for risk exposure data collection.

Automobile Driving↗
PubMed1993

Neck injuries among belted and unbelted occupants of the front seat of cars.

This article, part of a recently completed research project on safety belts, presents results on neck injuries. A total of 3927 injured front-seat occupants (drivers and passengers) involved in two-car crashes were studied. Among them, 725 sustained neck sprains (ICD-9 code 847.0); some of them may have sustained other injuries as well. The more serious injuries to the cervical spine were more prevalent among the unbelted occupants. Neck sprains were relatively more numerous among belted occupants compared with unbelted ones, with a relative risk estimate of 1.68. Similar results hold also for subsets of the data on different types of collisions; the relative risks ranged from 1.39 to 2.42. A log linear model was constructed for the odds ratio (neck sprain vs. no neck sprain) taking into account the following factors: (1) seatbelt use, (2) direction of impact, (3) authorized speed limit, and (4) vehicle weight. The resulting relative risk estimate (belted vs. unbelted) became 1.58. The results raise questions about seatbelts and their protection against neck sprains.

Accidents, Traffic↗
PubMed1993

Transcutaneous and end-tidal carbon dioxide pressures should be measured during pediatric polysomnography.

Pediatric obstructive sleep apnea (OSAS) is characterized by partial airway obstruction, alveolar hypoventilation, and elevated arterial CO2 (PaCO2). Thus, a reliable, practical method of estimating CO2 is needed for pediatric polysomnography. Therefore, we measured both transcutaneous CO2 (PtcCO2) and end-tidal CO2 (PETCO2) in 15 pediatric polysomnographic evaluations. Sleep state, the highest PtcCO2, and the highest PETCO2 were recorded for 5,159 thirty-second epochs. Although PtcCO2 and PETCO2 were available for 78.5 and 73.0% of epochs, respectively, at least one estimator was available for 92% of the epochs. One infant who would not tolerate a nasal sampling catheter had no PETCO2 data. For 13 of 14 studies there was a relatively constant difference between PtcCO2 and PETCO2. The difference between PtcCO2 and PETCO2 was within 4 mm Hg in 63.9% of 3,072 epochs. Across 14 studies, mean PtcCO2 exceeded mean PETCO2 by 2.8 +/- 3.0 mm Hg, and it was within 4 mm Hg in 10 studies. In three subjects, PETCO2 was intermittently or consistently less than PtcCO2 because of tachypnea, increased physiologic dead space, or severe partial airway obstruction; in one subject PtcCO2 exceeded PETCO2 for undetermined reasons during one electrode application. The results of this study indicate that PtcCO2, as well as PETCO2, should be measured during pediatric polysomnography. By utilizing both PtcCO2 and PETCO2 there was a 70% reduction in the number of epochs that could not be assessed for hypoventilation. For an individual subject or electrode application there was a constant, and usually close, relationship, between PtcCO2 and PETCO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Gas Monitoring, Transcutaneous↗
PubMed1991

Complement deposition by antibodies to Pseudomonas aeruginosa mucoid exopolysaccharide (MEP) and by non-MEP specific opsonins.

The failure of cystic fibrosis patients to limit chronic infection due to mucoid Pseudomonas aeruginosa might be due to ineffective opsonins produced against this bacterium. Nonopsonizing antibody to the bacterial capsule, mucoid exopolysaccharide (MEP), appears at elevated titers during chronic colonization of cystic fibrosis patients, as do opsonins not specific for MEP. Nonopsonic antibodies to MEP occur naturally in most adults and can be induced in animals by immunization. A limited number of humans produce MEP-specific opsonic antibodies after immunization. The purpose of this study was to compare the activation and deposition of C components onto the bacterial surface in the presence of these different antibodies. Opsonic killing uses the classical C pathway. MEP-specific opsonic and nonopsonic antibodies bound to whole bacteria and activated C to a comparable degree, but opsonic antibody deposited 3 to 40 times more C3 onto bacteria, mostly as C3bi, compared to nonopsonic antibody. In addition, two to three times as much nonopsonic mAb as opsonic mAb (both IgG2b) bound to the bacteria at comparable input concentrations, indicating the difference in C deposition was not due to differences in antibody binding. Non-MEP-specific opsonins also bound C3 to the bacteria, but only a mean of 27 +/- 14% was ester linked, compared with 81 +/- 11% of C3 deposited by MEP-specific opsonins. Immunoprecipitation experiments indicated that two-thirds of the C3 bound in the presence of MEP-specific opsonins was linked to MEP, whereas non-MEP-specific opsonins obtained from infected patients deposited the C3 onto LPS and other unidentified Ag. These data show that MEP-specific opsonins function by depositing C3 onto the outer bacterial surface that differentiates them from non-MEP-specific opsonins produced in response to chronic infection.

Animals↗
PubMed1991

[Exposure to the risk of traffic accidents, a fundamental epidemiological parameter, and one difficult to measure].

This is a review of the literature dealing with exposure to the risk of traffic accidents. We present the principal definitions of this concept, the different measures of risk exposure, indicators of the risk of traffic accidents, and the advantages and disadvantages of the methods used for the collection of data. The validity of the measure of exposure to risk is analyzed as well. We conclude that while distance travelled is the principal measure of exposure to risk accepted by the research community, it is necessary to use a composite measure which also takes into account the risk associated with the driver.

Accidents, Traffic↗
PubMed1988

BAY-K-8644-stimulated amylase secretion from pancreatic acinar cells.

Pancreatic acinar cells do not contain depolarization-sensitive calcium channels. Nonetheless, in the current study, the calcium channel activator, BAY-K-8644, was found to stimulate a time- and concentration-dependent increase in the spontaneous release of amylase. Secretion was dependent on the presence of extracellular calcium in the incubation medium. Racemic BAY-K-8644 and (or) its S(-)optical isomer did not enhance the secretory response to either carbachol or cholecystokinin octapeptide; however, when co-applied with either phorbol ester, vasoactive intestinal peptide, or forskolin, they potentiated amylase secretion. Nifedipine and the R(+)isomer of BAY-K-8644, which are both calcium channel antagonists, did not alter basal or forskolin-stimulated amylase secretion, and [3H]nitrendipine did not bind to acinar cell membranes. Neither atropine nor dibutyryl cGMP, inhibitors of cholinergic and cholecystokininergic receptors, respectively, affected BAY-K-8644-induced amylase secretion. While BAY-K-8644 stimulated concentration-dependent cGMP synthesis in acinar cells, it had no effect on basal or forskolin-stimulated cAMP formation. The data suggest that BAY-K-8644 may bind to acinar cell sites that are not functional calcium channel proteins but are coupled nevertheless to the secretory response, and that calcium channel antagonists do not bind to these sites. The mechanism of the secretagogue action of BAY-K-8644 remains to be elucidated.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

Threshold variability with an automated LED perimeter.

The CooperVision Dicon AP 2000 does not project the stimulus onto an existing background, but produces the test stimuli with light emitting diodes (LEDs) recessed in a dark cavity in the perimetric bowl. Nearly everywhere in the visual field, the visibility threshold with the Dicon instrument seems equivalent to that obtained with projection perimeters, but in the most sensitive retinal areas we found the threshold stimulus (Is) to be sometimes dimmer than the "background" (Ib), which surrounds the stimulus, making a negative differential threshold (delta L = Is - Ib). In other words, where a dark cavity is imaged on a very sensitive portion of the retina, the visual mechanism may perceive the switching on of a stimulus of a lower intensity (Is) than the "background" light (Ib) that floods only the surrounding retina. In retinal regions where this happens, we found the variability of retesting of threshold to be much greater than at locations with threshold stimuli that are more intense than the "background". When we modified the instrument by placing a diffuser over the LED to provide a preexistent "background" at the test location equivalent to that of the surround, the greater variability disappeared, and the threshold results resembled those of projection perimetry even at the most sensitive retinal areas. Variability was also reduced with shortened stimulus durations.

Adult↗
PubMed1986

Polysaccharide surface antigens expressed by nonmucoid isolates of Pseudomonas aeruginosa from cystic fibrosis patients.

We tested nonmucoid Pseudomonas aeruginosa isolates obtained from cystic fibrosis (CF) patients for the expression of lipopolysaccharide (LPS) serotype antigens, serum sensitivity, and production of mucoid exopolysaccharide (MEP). When all nonmucoid isolates were compared with a set of random mucoid isolates, 20 of 52 (38%) nonmucoid isolates were typable and serum resistant, compared with 13 of 51 (24%) mucoid isolates (P = 0.16 by chi-square analysis). However, nonmucoid strains from CF patients colonized only with nonmucoid strains were more frequently typable and serum resistant (67%) than were nonmucoid isolates from patients cocolonized with mucoid strains (31%) (P = 0.012, Fisher exact test). An inhibition enzyme-linked immunosorbent assay done with bacterial extracts, a direct-whole-cell enzyme-linked immunosorbent assay done with affinity-purified antibody to MEP, and immune electron microscopy all demonstrated production of MEP by all nonmucoid P. aeruginosa isolates tested, including nonmucoid revertants of mucoid strains. No other bacterial species tested positive in these assays. These findings suggest that MEP is produced by all P. aeruginosa isolates obtained from CF patients, that the initial colonizing nonmucoid strains produce a smooth LPS, and that once LPS-rough, mucoid strains appear in the sputum, the predominant LPS phenotype is rough regardless of colony morphology.

Antigens, Bacterial↗