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Biomedical subjects

L Dufour

Publications and source records attributed to L Dufour.

At least 19 recordsLinked to original sources
PubMed2001

The effects of sodium arsenite exposure on behavioral parameters in the rat.

Arsenic is a metalloid widely present in the environment. It is found in well water, soil, and air, and is also released from mining residues and industrial debris, among other anthropogenic sources. It has been previously reported that the content of catecholamines in striatum, hippocampus, and other cerebral regions changes in mice and rats exposed to arsenic. Few studies have examined behavioral alterations after intoxication with arsenic, and both increased and decreased locomotor activity, as well as learning deficits, have been described. In order to characterize the behavioral alterations induced by arsenic exposure, we exposed adult male Sprague-Dawley rats to 5, 10, and 20 mg/kg of arsenic by intragastric route for 2 or 4 weeks. Exposed rats showed reduced locomotor activity, which returned to control levels at the end of the intoxication period. We also found an increase in the number of errors in an egocentric task, alterations in monoamine content in midbrain and cortex, and increases in arsenic brain concentration, which were related to time of the exposure but not dose. These results indicate that short-term arsenic exposure induces neural and behavioral changes that may reflect a neurotoxic effect, and that these alterations are correlated to dose, time of exposure, and experimental conditions.

Animals↗
PubMed2000

Effects of arsenite on central monoamines and plasmatic levels of adrenocorticotropic hormone (ACTH) in mice.

We studied the effects of chronic arsenic exposure on brain monoamines and plasma levels of adrenocorticotropic hormone (ACTH) of mice. After weaning, mice received arsenic (0, 20, 40, 60 or 100 ppm) in drinking water over a period of 9 weeks. Monoamine content was quantified in different brain regions, arsenic was quantified in brain tissue and ACTH levels in plasma. Brain arsenic concentrations up to 200 ng/g showed a significant correlation with exposure levels and produced slight modifications in regional monoamine levels. ACTH plasma levels were significantly associated with norepinephrine (NE) concentrations in the medulla and pons, but not with hypothalamic NE levels. ACTH levels were significantly higher in the group exposed to 20 ppm. Dopamine showed significant dose-related decreases in the hypothalamus. These results show that chronic sodium arsenite exposure produces changes in central monoamines, which are not associated on a dose-dependent basis with major alterations in plasma ACTH.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1999

CD4(+) T cells and the proinflammatory cytokines gamma interferon and interleukin-6 contribute to alveolar bone loss in mice.

In this study, we used a mouse model to examine the role of the adaptive immune response in alveolar bone loss induced by oral infection with the human gram-negative anaerobic bacterium Porphyromonas gingivalis. Severe combined immunodeficient mice, which lack B and T lymphocytes, exhibited considerably less bone loss than did immunocompetent mice after oral infection, suggesting that lymphocytes contribute to this process. Bone loss after oral infection was decreased in mice deficient in major histocompatibility complex (MHC) class II-responsive CD4(+) T cells, but no change in bone loss was observed in mice deficient in MHC class I-responsive CD8(+) T cells or NK1(+) T cells. Mice lacking the cytokine gamma interferon or interleukin-6 also demonstrated decreased bone loss. These results suggest that the adaptive immune response, and in particular CD4(+) T cells and the proinflammatory cytokines that they secrete, are important effectors of bone loss consequent to P. gingivalis oral infection. The studies also reinforce the utility of the mouse oral infection model in dissecting the pathobiology of periodontal disease.

Adaptation, Physiological↗
PubMed1998

Effects of oral exposure to mining waste on in vivo dopamine release from rat striatum.

Several single components of mining waste (arsenic, manganese, lead, cadmium) to which humans are exposed at the mining area of Villa de la Paz, Mexico, are known to provoke alterations of striatal dopaminergic parameters. In this study we used an animal model to examine neurochemical changes resulting from exposure to a metal mixture. We used microdialysis to compare in vivo dopamine release from adult rats subchronically exposed to a mining waste by oral route with those from a control group and from a sodium arsenite group (25 mg/kg/day). We found that arsenic and manganese do accumulate in rat brain after 2 weeks of oral exposure. The mining waste group showed significantly decreased basal levels of dihydroxyphenylacetic acid (DOPAC; 66.7 +/- 7.53 pg/ microl) when compared to a control group (113.7 +/- 14.3 pg/ microl). Although basal dopamine release rates were comparable among groups, when the system was challenged with a long-standing depolarization through high-potassium perfusion, animals exposed to mining waste were not able to sustain an increased dopamine release in response to depolarization (mining waste group 5.5 +/- 0.5 pg/ microl versus control group 21.7 +/- 5.8 pg/ microl). Also, DOPAC and homovanillic acid levels were significantly lower in exposed animals than in controls during stimulation with high potassium. The arsenite group showed a similar tendency to that from the mining waste group. In vivo microdialysis provides relevant data about the effects of a chemical mixture. Our results indicate that this mining waste may represent a health risk for the exposed population.

Administration, Oral↗
PubMed1995

Inverse correlation between the proportion of salivary bacteria inhibiting Streptococcus mutans and the percentage of untreated carious teeth.

To evaluate the role of inhibitory substances produced by bacteria in the oral cavity, we estimated, by a deferred test on Todd-Hewitt agar enriched with hemin and vitamin K, the proportion of bacteria that inhibited or stimulated the growth of Streptococcus mutans and Porphyromonas gingivalis, from the saliva of 109 patients (54 males and 55 females) attending our dental clinics. The patients, aged from 8 to 75 years old (mean: 31 +/- 18 years), were randomly selected whatever the reason for their visit. The results, evaluated with the Spearman rank test, indicated that there was no statistically significant (P > 0.05) correlation between the proportion of salivary bacteria inhibiting or stimulating P. gingivalis with the Community Periodontal Index of Treatment Needs (CPITN), the number of carious, missing and filled teeth, or with the decayed, missing and filled teeth index (DMFT). Also, no statistically significant correlation was observed between the proportion of salivary bacteria stimulating the growth of S. mutans and the above mentioned health indexes. However, a statistically significant (P < 0.005) negative correlation was found between the percentage of cultivated bacteria that inhibit S. mutans and the percentage of untreated carious teeth as well as with the CPITN. The results thus indicate a possible role for inhibitory substances produced by bacteria in the maintenance of oral health.

Adolescent↗
PubMed1993

Effectiveness of soft laser treatment in periodontal surgery.

The aim of this study was to determine the analgesic, anti-inflammatory and healing effects of soft-laser treatment in a double-blind crossover study of periodontal post-surgical patients. For each patient, mucogingival procedures were required on contralateral sides of the mouth for similar problems. Twenty-eight patients had a total of 28 pairs of surgical procedures performed. Prior to surgery, a complete examination was carried out, scaling and root planing were performed, and oral hygiene instructions were given. Following surgery on both sides of the mouth, one site was lased and a placebo procedure was carried out on the other site. The patients evaluated pain three times a day for one week (modified McGill pain scale). An inflammatory index (Loe and Silness Index) was ascertained at days 7 and 14 for both sides of the mouth. A healing score (Landry, Turnbull, Howley Index) was evaluated at days 7 and 14. For both surgical procedures, the assessments were carried out in the same manner. Univariate and multivariate analyses of variance were performed for all parameters. The results showed no significant differences in the gingival index, healing index and pain reduction when the soft laser treatment was compared to the placebo operation. These results suggest that soft laser (As-Ga and He-Ne) treatments may not be a useful adjunct after certain periodontal surgical procedures.

Adult↗
PubMed1991

[Adolescents' fear of dental treatment: development and evaluation of a cognitive inventory].

Morin et al.'s Inventaire cognitif de la peur des traitements dentaires pour adolescent(e)s [Adolescents' Fear of Dental Treatment Cognitive Inventory] was administered to 343 subjects. Factor analysis revealed a single general factor that accounted for 33.5 per cent of the total variance. A reliability test revealed an alpha coefficient of 0.91, which was quite acceptable. A measure of test-retest reliability over a four-week period (N = 181) indicated that the scale was stable over time (r = 0.85). Standard error of measurement was found to be 4.63. Normative data are provided along with a description of the final version of the scale.

Adolescent↗
PubMed1991

[Concomitant and discriminatory validity of the Adolescents' Fear of Dental Treatment Cognitive Inventory].

The revised edition of the Inventaire cognitif de la peur des traitements dentaire pour adolescent(e)s [Adolescents' Fear of Dental Treatment Cognitive Inventory] (ICPTD-A) was administered to 38 subjects chosen at random and to nine subjects chosen with an obvious dental phobia problem. Its concomitant validity was established by relating the ICPTD-A scores to those of a behavioral test. The Pearson correlation coefficients that were thus obtained were -0.66 for the general population and -0.87 for the population suffering from dental phobia. The discriminatory validity was then established with a repeated measurement variance analysis based on the scores of the dental phobics after the administration of a recognized psychological treatment program intended to reduce their phobia. The results have shown a statistically significant difference between the experimental and control groups as well as a significant difference between pre- and posttreatments. The authors have therefore concluded that the ICPTD-A is a valid tool for the assessment of dental phobia in 12-15-year-old adolescents.

Adolescent↗
PubMed1990

[Use of pit and fissure sealants in private practice: the Quebec situation].

This paper presents data collected in March of 1989 from a sample of dentists practicing in the province of Quebec. A survey was mailed to dentists in order to determine to what degree sealants are used and the various characteristics relative to the dentists in question. Other questions related to how dentists obtained information about sealants, the difficulties encountered with their application and the problems relative to their use by the dental profession. The results indicate that nearly three quarters of Quebec dentists use sealants at least sometimes. This level of usage is comparable to American findings. A dentist is more likely to use sealants, if he is a recent graduate, a female dentist, and in a child-oriented group practice. A high proportion of dentists (2/3) use sealants selectively (in less than 25% of their patients). According to the dentists surveyed, the main obstacle to using sealants is the lack of coverage by the government dental program and the public's ignorance of the benefits of sealants. Most dentists who admitted never trying sealants, reported that they simply preferred to place an amalgam filling. In general, dentists knew the indications for sealants and had a positive attitude relative to their use.

Attitude of Health Personnel↗
PubMed1989

Detection and characterization of antigens from Taenia solium cysticercus in cerebrospinal fluid.

Dot-ELISA and standard-ELISA were used to detect T. solium cysticercus antigens in cerebrospinal fluid for the diagnosis of neurocysticercosis. The results indicate that both assays are sensitive, specific and economically adequate for the diagnosis of this disease. Using SDS-PAGE, electroblotting and dot-ELISA we have found that the antigen is a protein with a molecular weight of 66,000 daltons.

Adult↗
PubMed1989

Determination of trans-phylloquinone in children's serum.

By optimizing the conditions for determining trans-phylloquinone and its metabolite, K-2,3-epoxide, in serum through a two-step HPLC process combined with fluorometric detection after coulometric reduction, we have been able to develop a method applicable to small volumes of serum (200 to 500 microL). The limit of detection (signal-to-noise ratio of 3) was 15 ng/L for trans-phylloquinone, 30 ng/L for K-2,3-epoxide. The trans-phylloquinone concentrations measured by this method in serum from 82 children, ages one to six years, whose results were normal for overall coagulation tests, ranged from 40 to 880 ng/L (median 175 ng/L). We discuss these findings and compare them with vitamin K1(20) values reported for adults.

Child↗
PubMed1987

Detection of Cysticercus cellulosae antigens in cerebrospinal fluid by dot enzyme-linked immunosorbent assay (Dot-ELISA) and standard ELISA.

The dot enzyme-linked immunoassay and standard enzyme-linked immunoassay were used to detect Cysticercus cellulosae antigens in cerebrospinal fluid of patients suffering with neurocysticercosis. Using the dot enzyme-linked immunoassay, 10 of 17 patients (59%) were positive at a reciprocal titer of 128 (range 128-1,024). In the standard assay, 13 of 17 (77%) were positive (range 128-512). Specificity was 100% in both assays using 48 cerebrospinal fluids from patients with various central nervous system infections. The quantification of antigens in cerebrospinal fluid using standard assay and photometric readings showed a range of 17 to 138 ng/ml. The results indicate that both assays are sensitive, specific, and economical for the diagnosis of neurocysticercosis.

Adult↗
PubMed1984

Treatment of neurocysticercosis with flubendazole.

Thirteen patients with neurocysticercosis were studied and treated with flubendazole. Diagnostic procedures included computerized tomography (CT) and enzyme-linked immunosorbent assay. In 12 cases treatment with the drug led to clinical improvement. CT showed that some cysts regressed in size, and in two patients they disappeared. The treatment also lowered the antibody levels. The drug was well tolerated and no allergic reaction or other side effects were observed.

Adult↗
PubMed1981

Pre-exposure to the first dental treatment.

The present study attempts to verify the relative efficacy of two forms of pre-exposure which are identical in content and parallel in mode of exposure (in vivo or videotape). These two forms of pre-exposure were given to 38 children, aged four to six years old, before their first dental visit. The results showed that all groups manifested relatively little negative behavior while seeing the dentist. The theoretical and methodological implications of this study are discussed.

Behavior Therapy↗