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Biomedical subjects

M Desrosiers

Publications and source records attributed to M Desrosiers.

At least 37 records · Page 2Linked to original sources
PubMed1996

Lack of effect of hot, humid air on response to nasal challenge with histamine.

We have previously shown that whole body exposure of human subjects to environmental conditions of 37 degrees C and 90% relative humidity (RH) prior to and during nasal challenge with antigen decreases the early response. In this study, we evaluated 1) whether the decreased responses observed resulted from decreased end organ sensitivity to histamine and 2) whether the effect of hot, humid air persisted after the subject exited the hot, humid environment. Ten asymptomatic seasonal allergic subjects and 11 nonallergic subjects were randomized to environmental chamber conditions of either 20 degrees C, 30% RH or 37 degrees C, 90% RH for 1 hour prior to and during performance of a nasal challenge with histamine. Twenty-two hours after exiting the environmental chamber, the allergic subjects were challenged with antigen. During both chamber conditions, histamine challenge was associated with a significant increase in all measured parameters compared to sham challenge, except for the sensations of pruritus and congestion. The response to histamine challenge was not different under the two experimental conditions or between allergic and nonallergic subjects. Following both exposure conditions, allergen challenge was associated with an increase in all measured parameters compared to sham challenge, with no significant difference between the two conditions. Exposure to 37 degrees C, 90% RH minimally affects the response to nasal challenge with histamine, and thus, the previously reported decreases in the early nasal response to antigen may primarily result from reduction in mast cell activation. The effect on antigen does not persist 22 hours after exposure.

Adult↗
PubMed1996

Unilateral nasal allergen challenge leads to bilateral release of prostaglandin D2.

BACKGROUND: Multiple mediators including prostaglandin D2 and leukotriene B4 have been shown to increase in nasal secretions during the early response to nasal challenge with antigen. OBJECTIVE: Our objective was to investigate the time course of prostanoid and leukotriene B4 release into nasal secretions on both the ipsilateral and contralateral side after a unilateral nasal allergen challenge. METHODS: We performed a controlled, randomized trial. Six volunteers were challenged unilaterally with antigen or diluent in a randomized order and discs were used to collect nasal secretions from both nostrils at 2 min intervals for 20 min after the challenge. Prostanoids and leukotriene B4 (LTB4) in recovered nasal secretions were measured by combined capillary gas chromatography-negative ion chemical ionization mass spectrometry (GC/MS). RESULTS: Nasal allergen challenge resulted in a significant and immediate increase in symptoms and sneezing. PGD2 was significantly elevated above diluent values (0.6 +/- 0.6 pg) 30 s after removal of the allergen disc (P < 0.05), reached its peak (423.2 +/- 182.4 pg) at 2 min and then slowly decreased. PGD2 also increased on the contralateral side after unilateral allergen challenge, reaching peak values about six times lower than on the ipsilateral side (70.8 +/- 21.7 pg at 6 min). Levels of 9a, 11b-PGF2 after antigen provocation became significantly higher than after diluent (0 +/- 0 pg) on the ipsilateral side at 2 min (17.2 +/- 5.9 pg), and reached peak levels at 4 min (25.1 +/- 8.0 pg). LTB4 also increased significantly on the side of challenge. For the other prostanoids measured (PGF2, PGF2 alpha, TxB2, 6kPGF1 alpha), no significant changes in either ipsilateral or contralateral secretions were observed after allergen challenge. CONCLUSIONS: Our study described the kinetics of PGD2 and LTB4 release as well as the contralateral release of PGD2.

Adult↗
PubMed1993

Precise vocal cord medialization using an adjustable laryngeal implant: a preliminary study.

Treatment of symptomatic unilateral vocal cord paralysis is most frequently surgical. Medialization of the vocal cord using Teflon injection has proved effective; however, studies have shown this technique to produce stiffness of the vocal fold with loss of the "mucosal wave" and concomitantly poor vocal function. As well, overcorrection may occur and is not reversible. Isshiki type 1 medialization thyroplasty has been shown to produce a substantial improvement in vocal quality, as well as preserve the mucosal wave. A number of problems encountered during the performance of Isshiki type 1 thyroplasty has led us to modify the original technique. We have developed a new implant that allows for precise, easily adjustable control of vocal cord medialization. To evaluate the degree of vocal cord medialization afforded by this implant, larynges of fresh male and female cadavers were used as an experimental model. In both larynges, vocal cord medialization was shown to occur in a predictable fashion for the anterior, middle, and posterior segments, as well as in the functionally important inter-arytenoid region. We believe the use of this implant in medialization thyroplasty will allow precise, atraumatic medialization of the paralyzed vocal cord. This greater control over positioning and ease of adjustment should contribute to enhanced vocal quality.

Cadaver↗
PubMed1992

The mechanism by which an asymmetric distribution of plant growth hormone is attained.

Zea mays (sweet corn) seedlings attain an asymmetric distribution of the growth hormone indole-3-acetic acid (IAA) within 3 minutes following a gravity stimulus. Both free and esterified IAA (that is total IAA) accumulate to a greater extent in the lower half of the mesocotyl cortex of a horizontally placed seedling than in the upper half. Thus, changes in the ratio of free IAA to ester IAA cannot account for the asymmetric distribution. Our studies demonstrate there is no de novo synthesis of IAA in young seedlings. We conclude that asymmetric IAA distribution is attained by a gravity-induced, potential-regulated gating of the movement of IAA from kernel to shoot and from stele to cortex. As a working theory, which we call the Potential Gating Theory, we propose that perturbation of the plant's bioelectric field, induced by gravity, causes opening and closing of transport channels in the plasmodesmata connecting the vascular stele to the surrounding cortical tissues. This results in asymmetric growth hormone distribution which results in the asymmetric growth characteristics of the gravitropic response.

Biological Transport↗
PubMed1992

Studies on the growth and indole-3-acetic acid and abscisic acid content of Zea mays seedlings grown in microgravity.

Measurements were made of the fresh weight, dry weight, dry weight-fresh weight ratio, free and conjugated indole-3-acetic acid, and free and conjugated abscisic acid in seedlings of Zea mays grown in darkness in microgravity and on earth. Imbibition of the dry kernels was 17 h prior to launch. Growth was for 5 d at ambient orbiter temperature and at a chronic accelerational force of the order of 3 x 10(-5) times earth gravity. Weights and hormone content of the microgravity seedlings were, with minor exceptions, not statistically different from seedlings grown in normal gravity. The tissues of the shuttle-grown plants appeared normal and the seedlings differed only in the lack of orientation of roots and shoots. These findings, based upon 5 d of growth in microgravity, cannot be extrapolated to growth in microgravity for weeks, months, and years, as might occur on a space station. Nonetheless, it is encouraging, for prospects of bioregeneration of the atmosphere and food production in a space station, that no pronounced differences in the parameters measured were apparent during the 5 d of plant seedling growth in microgravity.

Abscisic Acid↗
PubMed1991

The large vestibular aqueduct syndrome and sensorineural hearing loss in the pediatric population.

Sensorineural hearing loss, associated with a dilated vestibular aqueduct, is often described as progressive. Since 1982, computed tomography of the mastoids has become part of the routine investigation of deaf children at Sainte-Justine Hospital. Using clinical, audiometric and radiological material from 130 patients with sensorineural hearing loss, we identified 18 patients with enlarged vestibular aqueducts. The large vestibular aqueduct population was then compared to the normal vestibular aqueduct patients in regard to the degree and evolution of the sensorineural hearing loss. Progression of hearing loss was noted in 46% of patients in the presence of large vestibular aqueducts as compared to 35% in the absence of this anomaly. Normal radiographic findings did not exclude the possibility of further hearing loss.

Child↗
PubMed1990

Evaluation of biotinylated DNA probes for the detection of gene rearrangements in clinical specimens.

To determine whether a nonisotopic procedure is suitable for analyzing clinical specimens for gene rearrangements, the authors hybridized DNA from 15 specimens of lymphoid tissue with biotinylated DNA probes directed to J beta I + J beta II (T-cell receptor beta chain gene), JH (immunoglobulin gene heavy chain J region), and J kappa (immunoglobulin gene kappa light chain J region). Five cases of benign lymphoid hyperplasia, one case of dermatopathic lymphadenopathy, and one case of small noncleaved follicular center cell lymphoma had germline hybridization patterns when digested with Bam HI, Eco RI, and Hind III restriction endonucleases. Four cases of B-cell lymphoma and three cases of T-cell lymphoma had clearly detectable rearrangements of the genes for immunoglobulin or the T-cell receptor or both. One case of dermatopathic lymphadenopathy had a faint, clonal rearrangement of the T-cell receptor after digestion with Eco RI and Bam III. The authors conclude that biotinylated DNA probes can be useful for analyzing gene rearrangements in clinical specimens.

Biotin↗
PubMed1990

Anti-HIV antibodies and other serological and immunological parameters among normal Haitians in Montreal.

A matched-pair, cross-sectional study of lymphocyte and serological parameters associated with acquired immune deficiency syndrome (AIDS) in 189 randomly chosen, ostensibly healthy adult Haitian immigrants residing in Montreal matched for sex, age (within 5 years), and neighborhood of residence to 189 non-Haitian (Caucasian) controls was done in 1983-1984. Three years later (1986-1987), 41 of the Haitian study subjects and 83 of the non-Haitian controls participated in a follow-up study centered on lymphocyte parameters. A significantly greater number of Haitians than controls had produced antibodies to Toxoplasma gondii. In addition, a greater percentage of the Haitians than the controls were also producing antibodies to two other opportunistic pathogens frequently encountered in AIDS, cytomegalovirus and hepatitis B virus, implying that the Haitians in general had had greater exposure to a variety of infectious agents than had the controls. A few study participants were producing antibodies against two viruses that are related to the human immunodeficiency virus-type 1 (HIV-1), the human T-cell lymphotropic viruses I and II (HTLV-I and -II). Two Haitians and one control were producing antibodies against HTLV-I. One study subject and four controls were HTLV-II seropositive. The most interesting and surprising finding was that four (2.1%) of the Haitian study subjects but none of the controls were seropositive for HIV-1. These individuals, two of whom were women and two men, were asymptomatic. Although their individual lymphocyte parameter values fell in the normal range, as a group they had statistically significantly lower average values for their lymphocyte parameters than did the HIV-seronegative Haitian study objects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Tac expression induced by Epstein-Barr virus is restricted on non-transformable B lymphocytes.

During the course of a comparative study dealing with the immortalization of lymphocytes from a large number of normal healthy donors, we found that B cells of two of these individuals could not be immortalized by Epstein-Barr virus (EBV) under the standard conditions. The expression of the Tac antigen on the membrane of EBV-infected B cells from these two donors was compared with that of B cells from EBV immortalization-susceptible ones. The method used was two-colour immunofluorescence cytofluorometer analysis. We found that the Tac antigen expression was significantly and repeatedly reduced in the case of the two immortalization-resistant donors. This difference might be related to a genetic control of the resistance to EBV-immortalization.

B-Lymphocytes↗
PubMed1985

Immunologic findings in healthy Haitians in Montreal.

To investigate the occurrence of acquired immune deficiency syndrome in Haitians, a health status questionnaire was administered and selected studies of immune status done in a randomly chosen sample of 189 healthy adult Haitians living in Montreal. The study group was comparable to a large sample of Haitians in Montreal interviewed in the 1981 census with respect to age, sex, number of persons per household and year of immigration, but the proportion of currently married people in the study was larger (60.8% v. 42.6%). The results in the study group were compared with those in a sample of 189 non-Haitians matched for age, sex and neighbourhood of residence. Persons with known causes of impaired immune function were excluded. The participation rate was 87.5%. The study and control groups both reported few symptoms and chronic health problems and had comparable demographic data, including rate of employment and income. The mean total numbers of lymphocytes, OKT3 and OKT4 (helper) and OKT8 (suppressor) cells were significantly higher in the Haitians than in the controls, though still within normal limits. There was a borderline elevation of the lymphocyte response to phytohemagglutinin in the Haitians. The ratios of helper to suppressor T cells in the two groups were, however, not significantly different. The Haitians, in comparison with non-Haitians living in the same community, had no demonstrable abnormalities of cellular immune function.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Feasibility of strict diabetes control in insulin-dependent diabetic adolescents.

Nineteen insulin-dependent diabetic adolescents who had poor control on twice daily injections and home glucose monitoring participated in a study assessing the feasibility of improved control. Using a randomized crossover protocol, we examined the relative efficacy of continuous subcutaneous insulin infusion and of intensive conventional therapy with three or four daily injections of insulin. Both therapies were regulated with home glucose monitoring. A marked improvement in control with both therapies was observed when mean blood glucose and glycosylated hemoglobin A1 were compared with conventional therapy. However, pump therapy resulted in significantly lower HbA1 than intensive therapy (P less than 0.05), despite a significantly lower total insulin dose (P less than 0.01). We conclude that in adolescents with type I diabetes, continuous subcutaneous insulin infusion is more effective in achieving improvement of diabetes control than is intensive conventional therapy in the outpatient setting.

Adolescent↗
PubMed1983

Mouse immune response to meningococcal antigens.

The mouse immune response against Neisseria meningitidis was studied by using an extract from group Y (Slaterus) known to contain protein antigens common to other meningococci. By using a solid-phase radioimmunoassay, high titers of specific IgM and IgG class antibodies were measured which lasted over 2 months after immunization. These antibodies cross-reacted with similar extracts from other meningococci groups. Bactericidal antibodies directed against protein antigens were also elicited after immunization and they belonged to IgM, IgG2a, and IgG2b isotypes. Cellular immunity, expressed as delayed type hypersensitivity under the conditions tested, could be detected neither in homologous nor heterologous reactions.

Animals↗
PubMed1983

Prevention of the enhancing effect of mucin and iron in mouse meningococcal infection.

In vivo resistance of mice to Neisseria meningitidis was entirely abrogated by a concomitant administration of mucin and iron with N. meningitidis organisms. Resistance, however, was restored when the latter challenge was given to animals which had been immunized 7 days previously with a crude extract of meningococcal antigens (MA), BCG, or proteose peptone. These results suggest that depression or activation of the reticuloendothelial system (RES) may be important in resistant of mice to meningococcal infection. Also, like BCG, MA inoculation was able to prevent infection by Listeria monocytogenes indicating its marked ability to activate the RES. The data show that immunization can induce nonspecific RES stimulation and that the nonspecific resistance persists for at least 7 days.

Animals↗
PubMed1980

Measurement of supernatural belief: sex differences and locus of control.

Although we live in an age dominated by science and technology, there exists an increasingly popular anti-science sentiment. This study describes the development of a scale to assess the degree of personal acceptance of supernatural causality versus acceptance of scientific explanation. In addition to the psychometric data concerning validity and reliability of the scale, data are presented which showed the personality factor of supernaturalism to be independent of orthodox religious attitudes. Results indicated a significantly greater supernatural acceptance for women, and a positive relation of supernaturalism with external locus of control.

Journal Article↗
PubMed1976

Immunological features in multiple sclerosis.

A clinical and laboratory profile of the immunological system of patients with multiple sclerosis (MS) strongly suggested that many specific immune deficiencies exist in MS. The immunological history showed that patients with MS had had more tonsillectomies, appendicectomies, and childhood infections than matched controls, which suggested that there had been problems in controlling various types of childhood infections. The cell-mediated immune response and the circulating antibody titres were specifically impaired against a variety of antigens. Patients with MS had significantly lower serum antibody titres than controls against many naturally occurring antigens-namely, diptheria and tetanus toxoids, adenovirus, and mumps viruses. Raised serum antibody titres were found against measles and varicella zoster viruses while no difference was found towards other antigens. The delayed hypersensitivity reaction and the immunological memory of patients with MS were also greatly reduced against the mumps skin test antigens. There were normal amounts of circulating T and B lymphocytes, and the phytohaemagglutinin, concanavallin A, pokeweed mitogen, and encephalitogens lymphocyte transformation was not different from that in controls. These results indicated that patients with MS have more infectious problems than normal people and that both their T and B cell systems cannot mount a fully normal immunological response to some viral and bacterial antigens, while they give an increased response to others.

Adult↗