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Biomedical subjects

S Beaulieu

Publications and source records attributed to S Beaulieu.

At least 37 records · Page 2Linked to original sources
PubMed1998

Emergency management of migraine: is the headache really over?

OBJECTIVES: To observe headache frequency after release for acute migraine sufferers treated in an ED; to observe the impact after-release headaches and associated symptoms have on quality of life; and to document the variability in migraine management in an emergency setting. METHODS: Prospective observational study, including 24- and 72-hour telephone follow-up. RESULTS: Over a 4-month period, 143 patients with headaches (149 visits) were observed in the ED. Of 108 patients successfully contacted, the incidence of headache in the first 24 hours after release was 49.1%. Forty-two patients left the ED without pain; 13 of these subsequently had return of headache. Sixty-six left with some degree of pain, with 40 having headache persistence at 24 hours. The difference in 24-hour headache rate between the 2 groups is significant (p=0.008). Five patients still had headaches at 72 hours after release, but 54 of 70 contacted had taken medication for their symptoms between 24 and 72 hours after release. Forty-five percent were not back to normal function at 24 hours, while 21 of 70 were still not sleeping well at 72 hours. Finally, 8 different classes of medications were used in the ED for migraine headaches, with 20 patients receiving at least 3 types of medication. CONCLUSIONS: Treatment for acute migraine headache in this emergency setting was variable. Patients not obtaining complete relief in the ED had a higher rate of headache after release than did those who left with no pain. Migraine sufferers may have normal daily function affected for up to 72 hours or longer after ED treatment.

Acute Disease↗
PubMed1997

Spatial memory in transgenic mice with impaired glucocorticoid receptor function.

Spatial learning and memory function of transgenic mice with impaired glucocorticoid receptor function was assessed in the Morris water maze and the radial arm maze. Transgenic mice took longer to find a submerged and a visual platform in the water maze task than did mice from the parent strain (B6C/3F1), although performance was improved in the visible platform condition relative to the submerged platform task. In the radial arm maze, transgenic mice made significantly more errors than B6C/3F1 mice. In both tasks, the behavioural strategies adopted by transgenic mice were non-optimal for correct performance. It is suggested that the impaired performance displayed by transgenic mice in both tests is largely attributable to these altered behavioural strategies.

Animals↗
PubMed1997

Behavioral reactivity to aversive stimuli in a transgenic mouse model of impaired glucocorticoid (type II) receptor function: effects of diazepam and FG-7142.

Transgenic mice with impaired type II-glucocorticoid receptor mediated feedback inhibition of hypthalamic-pituitary-adrenal activity were assessed in three different tests assessing behavioral reactivity to aversive stimuli, the elevated plus maze, the Thatcher-Britton novelty-conflict paradigm, and the startle paradigm. Transgenic mice more frequently entered and spent more time in the open arms of the elevated plus in comparison to B6C/3F1 mice. Transgenic mice took significantly longer to begin eating in the Thatcher-Britton novelty conflict paradigm, and displayed increased reactivity in the startle paradigm. Administration of 1 or 2 mg/kg diazepam reversed the behavioral effects observed in all three tests. Administration of the benzodiazepine receptor inverse agonist N-methyl-beta-carboline-3 carboxamide (FG-7142, 10 mg/kg) reduced the ratio of open to total arm entries and the time spent in the open arms of the plus maze in transgenic, but not B6C/3F1, mice. This dose of FG-7142 did not influence performance of either strain in the Thatcher-Britton or startle paradigms. These results are discussed in terms of the hypothesis that the transgenic mice are more sensitive to the aversive properties of novel stimuli, and that they may have difficulty discriminating between signals of relative safety and danger.

Animals↗
PubMed1996

Cardiovascular, neuroendocrine, and monoaminergic responses to psychological stressors: possible differences between remitted panic disorder patients and healthy controls.

Both clinical symptomatology and stress research suggest that panic attacks might be partially attributable to exaggerated psychophysiological responses to environmental stressors. In the present study, we aimed to explicitly test this idea by measuring the physiological responses to a mild psychological stressor in both healthy controls (n = 8) and fully remitted, medication-free panic disorder patients (n = 8). One hour before the stressor, former patients, compared to healthy controls, exhibited higher diastolic blood pressure. From a blood sample taken 30 min before the stressor, patients, compared to controls, had lower paroxetine platelet binding site densities. During the stressor, patients, compared to controls, had greater increases in plasma levels of cortisol. These preliminary findings suggest that remitted panic disorder patients might have disturbed physiological responses to mild psychological stressors. These disturbances might be related to the development of future episodes.

Adult↗
PubMed1996

In vitro characterization of purified human thymic dendritic cells infected with human immunodeficiency virus type 1.

In the thymus, dendritic cells (DC) are functionally associated with thymocytes and are recognized to play a major role in the intrathymic differentiation of T cells. Several studies have previously investigated the role of DC during HIV-infection, but the status of thymic DC in HIV-1 pathogenesis remains unclear. In this study, we investigated the susceptibility of purified human thymic DC to HIV-1 infection in vitro. HIV-1 was not detected in cell-free supernatants collected from HIV-infected DC. However, these cultures were shown to transmit HIV-1 infection since coculture with permissive MT4 cells resulted in virus production. The exposure of DC in culture to HIV-1 was shown to promote severe DC morphological changes and killing. We also found that one or several heat labile soluble cytotoxic agents present in the HIV-1-infected DC supernatant mediated the killing of thymocytes. Our observations raise the possibility that (1) the HIV-1-induced DC killing, (2) the capacity of DC to transmit viral infection, and/or (3) the release of HIV-1-mediated cytotoxic agent(s) from DC may contribute to AIDS pathogenesis in vivo.

Animals↗
PubMed1995

An improved method for purifying human thymic dendritic cells.

Thymic dendritic cells (DC) play a prominent role in the immune response as they constitute a key element involved in the maturation of thymocytes in the thymus. Human thymic DC, like DC from other lymphoid organs, represent a minor cell population (< 2%) of the thymus. Since these cells cannot replicate in vitro, the development of efficient purification methods is an essential prerequisite for extensive functional studies. DC express high levels of HLA-DR, a cell surface marker of the MHC class II antigen which is not exclusive to DC. Since no specific human thymic DC marker has been identified so far, DC purification methods are mainly based on depletion of particular subgroups of cells. We report here an improved method for purifying human thymic dendritic cells. In contrast to prior work, CD2+ thymocytes were first depleted by rosetting with neuraminidase treated sheep red blood cells. The nonrosetted cells were separated in a Percoll gradient, and the low-density cells were subsequently depleted of nondendritic cells by using thymocyte and macrophage specific monoclonal antibodies and either magnetic bead depletion or cytofluorometry. Cell populations (18-55 x 10(6) cells) obtained following magnetic bead purification were at least 80% HLA-DR+/CD2- and exhibited ultrastructural morphological features and functional activities such as those described previously for thymic DC. This improved method was compared with different purification approaches that use various combinations of cell density-based separation techniques and cell surface specific markers antibody reactivity. The magnetic beads depletion approach provided higher yields.

Antibodies, Monoclonal↗
PubMed1994

Activation of human immunodeficiency virus 1 gene expression by the src oncoprotein.

Several genes are induced constitutively in cells transformed by the v-src oncoprotein. This induction is generally dependent on the activation of transcription factors binding to src-responsive elements of the promoter. In previous studies, we showed that the induction of the CEF-4/9E3 cytokine gene by pp60v-src is dependent on the PRDII/kappa B domain of the promoter (Dehbi et al., 1992). In this investigation, we describe the activation of the HIV-1 LTR by pp60v-src and show that a region of 30 bp containing the two NF-kappa B binding sites is critical for activation of the promoter. The induction was dependent on transformation since non-transforming forms of pp60v-src had little or no effect on the promoter. The expression of proviral DNA and the release of p24 antigen were also increased by v-src indicating that viral replication was stimulated in src-transformed cells. The effect of v-src on HIV-1 gene expression occurred in the presence or in the absence of the tat viral trans-activator, in fibroblasts and in Jurkat T lymphocytes. These results indicate that several promoters controlled by PRDII/kappa B may be activated constitutively in v-src transformed cells and suggest that oncogenic tyrosine kinases may play a role in the induction of viruses with a PRDII/kappa B-controlled promoter.

Animals↗
PubMed1991

An analysis of frequencies of surgical procedures in Canada.

This paper reports preliminary and selected results of an analysis of the frequencies of 36 common surgical procedures in hospitals across Canada during the period April 1985 to March 1987. Age-sex-specific and age-sex-standardized procedure rates were calculated for each procedure for each of 245 Census Divisions (CDs) across Canada, as well as for 338 smaller urban areas (FSAs) within the province of Ontario. Special attention was given to adjusting the rates for differing population sizes of the geographical regions. Procedure rates were computed based on the residence of the patient, not on the location of the hospital. Graphical techniques, analysis of variance, and other statistical techniques were used to identify unusually high or low procedure rates and to determine effects due to differences in age, sex, and geographical region. The relationship of procedure rate to the socio-economic level of a region (as measured by the proportion of low-income individuals in the region) was analyzed.

Canada↗
PubMed1990

Differential regulation by dexamethasone of glucocorticoid receptor messenger RNA concentrations in neuronal cultures derived from fetal rat hypothalamus and cerebral cortex.

1. Differential regulation, by dexamethasone, of glucocorticoid receptor gene expression was studied in three different neuronal cultures derived from hypothalamus amygdala, and cerebral cortex. 2. Cellular glucocorticoid receptor (GR) mRNA concentration was measured by hybridization using a 32P-labeled RNA probe complementary to a 2.2-kb fragment of the glucocorticoid receptor mRNA. Changes in the amount of GR mRNA were evaluated in relation to the content of beta-actin mRNA. 3. In cells derived from either hypothalamus or cerebral cortex, we observed a complex pattern of GR mRNA concentrations which were characterized by cyclic variations of GR mRNA content during continuous treatment with dexamethasone for up to 72 hr. 4. In contrast to cells derived from the hypothalamus where a persistent 30-40% reduction in GR mRNA levels was seen for up to a least 72 hr, we observed, in cells derived from the cerebral cortex, a sustained increased (1.4-fold) of the GR mRNA at this same time interval.

Animals↗
PubMed1989

Antidepressants regulate glucocorticoid receptor messenger RNA concentrations in primary neuronal cultures.

Increased cortisol secretion, caused by hyperactivity of the brain-pituitary-adrenal axis, and non-suppression of cortisol secretion following dexamethasone administration are two characteristics frequently associated with major depression or the depressed phase of bipolar illness. Antidepressants, irrespective of their selective inhibitory actions on the re-uptake of serotonin or of norepinephrine, modify glucocorticoid receptor messenger RNA concentrations in primary cultures of rat hypothalamic or amygdaloid neurons in a biphasic manner, with predominant stimulatory effects. This suggests a mechanism whereby antidepressants, by restoring the sensitivity of the limbic-hypothalamic system to glucocorticoid feedback inhibition, reverse the hyperactivity of the brain-pituitary-adrenal axis.

Amygdala↗
PubMed1989

Influence of the central nucleus of the amygdala on the content of corticotropin-releasing factor in the median eminence.

The central nucleus of the amygdala possesses numerous neurons containing corticotropin-releasing factor (CRF). This study demonstrates a striking decrease of the CRF-like immunoreactivity in the median eminence at both 1 and 2 weeks after bilateral lesions of the amygdaloid central nucleus. Lesion of the amygdaloid central nucleus did not alter the neurophysin-like immunoreactivity in the internal zone of the median eminence, indicating the integrity of the efferent neurophysin-containing fibers of the supraoptic and paraventricular hypothalamic nuclei. However, there was a concomitant decrease of neurophysin and CRF-like immunoreactivity in the external zone of the median eminence. These results substantiate the hypothesis that the amygdaloid central nucleus can influence the content of CRF-like material in the median eminence via a multisynaptic pathway involving the synthesis of CRF at the level of the paraventricular nucleus of the hypothalamus. The exact mechanism by which lesion of the amygdaloid central nucleus influences the CRF content in the median eminence remains to be determined.

Amygdala↗
PubMed1988

Glucocorticoid regulation of proopiomelanocortin messenger ribonucleic acid content of rat hypothalamus.

We have verified the possibility that the POMC gene of the rat hypothalamus might be subject to regulation by glucocorticoids. Adrenalectomy increased the concentration of POMC mRNA in anterior pituitary and in hypothalamus, but not in the neurointermediate lobe of the pituitary gland. Dexamethasone and, to a slightly lesser extent, corticosterone treatments reversed the adrenalectomy-induced increase in POMC mRNA concentrations in both anterior pituitary and hypothalamus. Dexamethasone caused a slight decrease of POMC mRNA levels in the neurointermediate lobe of the pituitary gland, while corticosterone had no effect. These results indicate that the POMC gene of the rat brain hypothalamus is also under negative control by glucocorticoids.

Adrenalectomy↗
PubMed1987

Participation of the central amygdaloid nucleus in the response of adrenocorticotropin secretion to immobilization stress: opposing roles of the noradrenergic and dopaminergic systems.

Bilateral lesions of the amygdaloid central nucleus (ACE) significantly diminished the secretion of ACTH in response to immobilization stress. Stress is associated with increased noradrenergic activity in the ACE and in the anterior and lateral hypothalamic areas. In comparison with intact stressed animals, lesion of the ACE reduced the noradrenergic activity in response to stress within the anterior and lateral hypothalamic areas, the arcuate and paraventricular nuclei of the hypothalamus and the bed nucleus of the stria terminalis. These results support the hypothesis of a stimulatory role for the noradrenergic system in the ACE on ACTH secretion. Stress decreased dopaminergic activity in the ACE, the cortical nucleus of the amygdala, the dorsomedial and ventromedial nuclei of the hypothalamus and the ventral tegmental area. In comparison with intact stressed rats, lesion of the ACE reduced dopaminergic activity in the anterior and lateral hypothalamic areas. Our results support the hypothesis of an inhibitory role of the dopaminergic system, particularly in the ACE, on ACTH secretion. This study also indicates that, in the control of ACTH secretion in response to immobilization stress, the noradrenergic and dopaminergic systems act in opposition to one another in certain brain structures such as the anterior and lateral hypothalamic areas and the ACE.

Adrenocorticotropic Hormone↗
PubMed1986

Control of ACTH secretion by the central nucleus of the amygdala: implication of the serotoninergic system and its relevance to the glucocorticoid delayed negative feedback mechanism.

The possible implication of the amygdaloid central nucleus (ACE) of the rat in the control of ACTH secretion in response to immobilization stress was assessed. The ACTH secretion, in response to stress and/or bilateral lesions of the ACE, was correlated with the serotoninergic activity in specific hypothalamic and amygdaloid nuclei. Bilateral lesions of the ACE produced a striking decrease of plasma ACTH levels in response to stress. However, basal plasma ACTH levels measured between 7 and 11 a.m. were identical in both control and lesioned groups. Stress, applied to intact animals, did not modify the serotoninergic activity in any of the following areas: hypothalamic paraventricular (PVH), ventromedial (VMH) and dorsomedial (DMH) nuclei; the anterior hypothalamic area (AHA); the lateral part of the basal amygdaloid nucleus (ABL), the amygdaloid medial (AME) and cortical (ACO) nuclei. However, lesion of the ACE increased the serotoninergic activity in all these structures except for the VMH. Immobilization stress applied to lesioned animals decreased the serotoninergic activity to control levels in the PVH, AHA and DMH and decreased the activity to below control levels in the VMH. The serotoninergic activity remained at an increased level in the glucocorticoid receptor-rich areas of the amygdala, namely the AME, ACO and ABL nuclei. These results provide evidence for a stimulatory role of the central nucleus of the amygdala in the control of ACTH secretion. Moreover, they substantiate an implication of the amygdaloid complex in the control of the delayed negative feedback of glucocorticoids on ACTH secretion via interaction with the serotoninergic system.

Adrenocorticotropic Hormone↗
PubMed1985

Implication of the serotoninergic system in the decreased ACTH response to stress after lesion of the amygdaloid central nucleus.

The present study was designed to ascertain the possible implication of the serotoninergic system and the central amygdaloid nucleus in the control of ACTH secretion in response to immobilization stress. The response to immobilization stress of intact and lesioned animals was studied by monitoring the plasma and pituitary ACTH concentration and the activity of the serotoninergic system within specific hypothalamic and amygdaloid nuclei. Bilateral lesions of the central nucleus of the amygdala significantly decreased the secretion of ACTH in response to immobilization. Moreover, the serotoninergic activity in most of the hypothalamic and in all the amygdaloid nuclei studied was greatly increased. A 60-min immobilization stress prevented this increase in the hypothalamic nuclei but not in the amygdala. These results indicate that the central nucleus of the amygdala participates in the regulation of ACTH secretion in response to immobilization stress. Furthermore, they substantiate the hypothesis of a participation of the serotoninergic system in limbic areas, particularly in nuclei which contain neurons possessing glucocorticoid receptors such as the medial, basomedial and cortical amygdaloid nuclei.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Air pollution, aeroallergens and cardiorespiratory emergency department visits in Saint John, Canada.

Existing studies of the association between air pollution, aeroallergens and emergency department (ED) visits have generally examined the effects of a few pollutants or aeroallergens on individual conditions such as asthma or chronic obstructive pulmonary disease. In this study, we considered a wide variety of respiratory and cardiac conditions and an extensive set of pollutants and aeroallergens, and utilized prospectively collected information on possible effect modifiers which would not normally be available from purely administrative data. The association between air pollution, aeroallergens and cardiorespiratory ED visits (n = 19,821) was examined for the period 1992 to 1996 using generalized additive models. ED visit, air pollution and aeroallergen time series were prefiltered using LOESS smoothers to minimize temporal confounding, and a parsimonious model was constructed to control for confounding by weather and day of week. Multipollutant and multi-aeroallergen models were constructed using stepwise procedures and sensitivity analyses were conducted by season, diagnosis, and selected individual characteristics or effect modifiers. In single-pollutant models, positive effects of all pollutants but NO2 and COH were observed on asthma visits, and positive effects on all respiratory diagnosis groups were observed for O3, SO2, PM10, PM2.5, and SO4(2-). Among cardiac conditions, only dysrhythmia visits were positively associated with all measures of particulate matter. In the final year-round multipollutant models, a 20.9% increase in cardiac ED visits was attributed to the combination of O3 (16.0%, 95% CI 2.8-30.9) and SO2 (4.9%, 95%CI 1.7-8.2) at the mean concentration of each pollutant. In the final multipollutant model for respiratory visits, O3 accounted for 3.9% of visits (95% CI 0.8-7.2), and SO2 for 3.7% (95% CI 1.5-6.0), whereas a weak, negative association was observed with NO2. In multi-aeroallergen models of warm season asthma ED visits, Ascomycetes, Alternaria and small round fungal spores accounted for 4.5% (95% CI 1.8-7.4), 4.7% (95% CI 1.0-8.6) and 3.0% (95% CI 0.8-5.1), respectively, of visits at their mean concentrations, and these effects were not sensitive to adjustment for air pollution effects. In conclusion, we observed a significant influence of the air pollution mix on cardiac and respiratory ED visits. Although in single-pollutant models, positive associations were noted between ED visits and some measures of particulate matter, in multipollutant models, pollutant gases, particularly ozone, exhibited more consistent effects. Aeroallergens were also significantly associated with warm season asthma ED visits.

Air Pollutants↗