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Biomedical subjects

M Dugas

Publications and source records attributed to M Dugas.

At least 55 records · Page 3Linked to original sources
PubMed1994

Airway inflammation after removal from the causal agent in occupational asthma due to high and low molecular weight agents.

In order to determine 1) the features of airway inflammation after removal from exposure to high (HMW) and low (LMW) molecular weight agents 2) if there are any differences in the pattern of inflammation induced by these two types of agents, we studied 18 subjects with a recently confirmed diagnosis of occupational asthma (OA) due to HMW (n = 11) and LMW (n = 7) agents. The duration of asthma symptoms varied from 2 to 108 months (mean 33 months), and withdrawal from exposure to the sensitizing agent from 3 to 24 weeks (mean 10 weeks). All subjects underwent measurements of expiratory flow rates, methacholine inhalation tests, and a flexible bronchoscopy with bronchoalveolar lavage (BAL) and bronchial biopsies. Endoscopic findings were compared with a group of 10 normal subjects. At the time of the bronchoscopy, asthma symptoms were minimal in most subjects. Although 15/18 subjects had normal forced expiratory volume in one second (FEV1 > 80% pred), all subjects had increased airway responsiveness to methacholine (provocation concentration producing a 20% fall in FEV1 = 0.2-10.0 mg.ml-1). BAL analysis showed similar median percentages of the total number of cells and differentials in control subjects and those exposed to HMW and LMW agents. Bronchial biopsies showed that mean inflammatory cell count, both epithelial and sub-epithelial, was similarly raised in OA subjects exposed to either HMW or LMW agents, compared to controls, except for epithelial lymphocyte count. In contrast to the controls, bronchial biopsy of both groups with OA also showed other changes such as extensive epithelial desquamation, ciliary abnormalities of the epithelial cells, smooth muscle hyperplasia and subepithelial fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Neurological sequelae of the operation "baby lift" airplane disaster.

The aircraft disaster of the first flight of Operation "Baby Lift", which departed from Saigon, Vietnam, April 4, 1975, was survived by 149 orphaned children on their way to adoptive homes in the West. It had 157 passenger fatalities. The aircraft disaster exposed the surviving children to a complex disaster environment in which subatmospheric decompression, hypoxia, and deceleration were experienced, many children suffered a transient unconsciousness. We examined 135 surviving children between 1978 and 1985. The U.S. resident children were examined in the years 1979 to 1982 at an average age of 8 years and 6 months. They displayed the following symptomatology: attention deficit (> 75%), hyperactivity (> 65%), impulse disorder (> 55%), learning disabilities (> 35%), speech and language pathology (> 70%), and soft neurological signs (> 75%). The European children were examined in the years 1983 to 1985. On arrival at the adoptive home, 2 weeks after the accident they displayed the following symptomatology: muscle hypotonia (26%), seizures (2.5%), and regressed developmental milestones (33%). At the time of the diagnostic evaluations (1983 to 1985) the average age was 11 years and 8 months. They displayed the following symptomatology: attention deficit (59%), hyperactivity (52%), impulse disorder (48%), learning disabilities (43%), soft neurological signs (43%), epilepsy (16%), and speech and language pathology (34%). We conclude that a complex disaster environment can cause brain damage in children without prolonged unconsciousness, and that victims of disasters require a thorough evaluation from a multidisciplinary team.

Accidents, Aviation↗
PubMed1994

Occupational asthma due to heated polypropylene.

A 35 year-old nonatopic woman was referred to the hospital for possible work-related asthma. She had worked as an operator, at a plant producing polypropylene bags, for the previous four yrs. Her main complaint was a productive cough with dyspnoea and wheezing, as well as rhinitis over the past 3 yrs. She had been absent from work for 6 months on maternity leave, and had improved greatly. She was on a beta 2-adrenergic agent and had to take it at least four times daily. Baseline spirometry whilst at work showed marked airflow obstruction (forced expiratory volume in one second (FEV1) of 43% predicted (pred). After two months away from work FEV1 improved to 89% pred; provocative concentration of histamine causing a 25% fall in FEV1 (PC20) was 3.6 mg.ml-1 (mild airway hyperresponsiveness). Return to work resulted in a marked deterioration in FEV1, and serial peak expiratory flow (PEFR) values. PC20 was 0.11 mg.ml-1 (severe airway hyperresponsiveness) one week after she had returned to work. Specific inhalation challenges with polypropylene heated to 250 degrees C resulted in a late asthmatic reaction. As formaldehyde is one of the degradation products of heating polypropylene, we exposed her to it for up to 2 h, but we elicited no bronchospastic reaction. We conclude that heated polypropylene should be listed as one of the agents that causes occupational asthma.

Adult↗
PubMed1994

[The use of diagnostic and surgical procedures in elderly persons in Quebec].

The rapid aging of the population constitutes a new challenge for the health care delivery system. This paper presents the progression of use of several diagnostic and surgical procedures in the elderly in Quebec from 1981 to 1989. Data were obtained from claims to the Régie de l'assurance maladie du Québec for the years 1981, 1985 and 1989. The rate of coronary artery bypass surgery increased by more than 700% in people 65 years and over between 1981 and 1989. This increase was especially high in the oldest age group (q 75 years). There was also a significant increase in surgery for abdominal aortic aneurysm, while the rate of carotid endarterectomy remained stable for people 65 years and over during this period. The rates of all abdominal surgical procedures examined (appendicectomy, repair of hiatal and inguinal hernia, cholecystectomy and colectomy) were relatively stable in elderly during the study period. Total hip replacement more than doubled in people 65 years and over, while other types of hip arthroplasty significantly decreased over this period. All types of diagnostic procedures examined (coronary angiography, bronchoscopy, gastroduodenoscopy and retrograd cholangio-pancreatography) increased significantly, especially in very old people. This study suggests that surgical care is increasing in the elderly in Quebec. This progression is expected to continue in the coming years so that surgical care of the elderly will become a significant part of our health care delivery system.

Aged↗
PubMed1993

Hypersensitivity pneumonitis-like reaction among workers exposed to diphenylmethane [correction to piphenylmethane] diisocyanate (MDI).

Isocyanates are well documented as a cause of occupational asthma. A hypersensitivity pneumonitis type of reaction has also been reported but only in a few isolated cases. We investigated nine subjects who complained of respiratory and general symptoms related to workplace exposure. All the subjects had worked in a plant where a resin based on diphenylmethane diisocyanate (MDI) is used in the manufacture of woodchip boards. They underwent inhalation challenges using the MDI resin for progressively increasing periods of time on separate days. In eight subjects, exposure to subirritant amounts of MDI induced a pattern of reaction consistent with hypersensitivity pneumonitis, i.e., significant falls in both FEV1 and FVC associated with a rise in body temperature (> 38 degrees C) and an increase in blood neutrophils (> +2,500/mm3). Bronchoalveolar lavage, performed in two subjects 24 h after the end of challenge exposure, revealed an increase in lymphocytes and neutrophils. Specific immunoglobulin G (IgG) and IgE antibodies to MDI human serum albumin (HSA) conjugates were present in all subjects. We conclude that the MDI resin caused an hypersensitivity pneumonitis type of reaction in at least eight (4.7%) of the 167 potentially exposed workers employed in the plant. These findings indicate that in some workplaces, a hypersensitivity pneumonitis type of reaction may be a more frequent consequence of isocyanate exposure than is usually thought.

Adult↗
PubMed1993

[Anorexia nervosa in a prepubescent child].

Anorexia nervosa in prepubescent patients is a serious pathology, which is often misunderstood, not exceptional and on the increase. Our study focuses on 13 case histories of children between eight and 12 years of age who met Tanner's first criterion (absence of puberty) and presented a substantial weight loss and a morbid fear of gaining weight. More specifically, we studied in our sample the general epidemiological data, the clinical features related to development (effect on growth, refusal of hydration), depressive comorbidity and a rather deteriorating evolution for the majority of our patients. Our results were compared with the data from the literature.

Age Factors↗
PubMed1993

[Attention deficit disorder and anxiety disorders: a co-occurrence study].

Recent epidemiological studies have evaluated the concomitant occurrence of several disorders in children. Over the last few years there have been reports from Anglo-Saxon investigators that many children with attention deficit disorder-hyperactivity also have anxiety disorders. This is the first French study addressing this issue. The prevalence and types of anxiety disorders were determined in 50 children with attention deficit disorder-hyperactivity using a questionnaire and a semi-structured interview. Over 40% of subjects had at least one concomitant anxiety disorder meeting DSM-III-R criteria. Hyperanxiety and separation anxiety were the most common anxiety disorders. Among patients with anxiety, over 40% had more than one anxiety disorder. These data are consistent with earlier Anglo-Saxon reports. Symptoms of anxiety which discriminated hyperactive children with and without anxiety disorders were identified.

Anxiety Disorders↗
PubMed1993

[Evolution of depression in the child and adolescent].

Outcome of depressive disorder in adolescents is now better known. Despite methodological differences between studies there is an agreement to emphasize frequency of relapse and recurrence in the follow-up (50 to 60%). Others modalities have also been described, anxiety disorders seemed to be the more frequent. For some authors, affective disorder in adolescents could presage manic depressive illness. Psychosocial functioning after the follow-up seems to be impaired as well as in professional, relational, or social fields. These data suggest a clear distinction between affective states in adolescents and symptoms related to psychological transformations of adolescence. We have conducted a follow-up study with adolescents hospitalized in the child and adolescent psychiatric department of R. Debré hospital, for major depressive episode (MDE) or dysthymic disorder (DD). On the 122 patients meeting initially inclusion criteria, 75 have been evaluated after one year follow-up at least. Duration of the follow-up was on average 4 years. 44 met initially DSM III and DSM III-R criteria for MDE and 31 for DD. Rating has been done during a phone interview with a standardized questionnaire. We did use criteria defined by Prien et al. (1984) for relapse, recurrence and remission. Our results showed a good short-term outcome in both groups (72.7% remission in MDE and 80.6% in DD). Relapse rate was superior in the first group. At the end of the follow-up, cumulative probability of recurrence was 52.9% in MDE group and 35.7% in DD group. Chronic evolution was more frequent in TD group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

An event-related potential study of controlled and automatic processes in 6-8-year-old boys with attention deficit hyperactivity disorder.

Event-related potentials (ERPs) were recorded from 2 groups (attention deficit hyperactivity disorder (ADHD) and normal control) of 12 boys aged from 6 to 8 years. Subjects were submitted to 2 different types of categorization tasks (with rare targets and frequent standards) implying either the use of a verbal class or that of an ordered series. Each type of task was performed twice, the first with reading and the second without. Amplitudes and latencies of a fronto-central N150-P250 complex, a parieto-occipital N250-P350 complex and a parieto-occipital P500 were measured. Regardless of the task, hyperactive children showed larger fronto-central P250, larger parieto-occipital N250 and smaller parieto-occipital P350s and P500s; moreover, the latencies of their parieto-occipital P350s were shortened. When the categorization depended on the use of a verbal class, ERP reading effects were significantly smaller in hyperactives than in normal controls for the parieto-occipital waves only. Alternatively, the target effects were significantly larger in hyperactive children but for the fronto-central P250 only. These results suggest that in ADHD automatic processes were enhanced when higher-order controlled processes were inadequate.

Aging↗
PubMed1992

Relation between veratridine reaction dynamics and macroscopic Na current in single cardiac cells.

Veratridine modification of Na current was examined in single dissociated ventricular myocytes from late-fetal rats. Extracellularly applied veratridine reduced peak Na current and induced a noninactivating current during the depolarizing pulse and an inward tail current that decayed exponentially (tau = 226 ms) after repolarization. The effect was quantitated as tail current amplitude, Itail (measured 10 ms after repolarization), relative to the maximum amplitude induced by a combination of 100 microM veratridine and 1 microM BDF 9145 (which removes inactivation) in the same cell. Saturation curves for Itail were predicted on the assumption of reversible veratridine binding to open Na channels during the pulse with reaction rate constants determined previously in the same type of cell at single Na channels comodified with BDF 9145. Experimental relationships between veratridine concentration and Itail confirmed those predicted by showing (a) half-maximum effect near 60 microM veratridine and no saturation up to 300 microM in cells with normally inactivating Na channels, and (b) half-maximum effect near 3.5 microM and saturation at 30 microM in cells treated with BDF 9145. Due to its known suppressive effect on single channel conductance, veratridine induced a progressive, but partial reduction of noninactivating Na current during the 50-ms depolarizations in the presence of BDF 9145, the kinetics of which were consistent with veratridine association kinetics in showing a decrease in time constant from 57 to 22 and 11 ms, when veratridine concentration was raised from 3 to 10 and 30 microM, respectively. As predicted for a dissociation process, the tail current time constant was insensitive to veratridine concentration in the range from 1 to 300 microM. In conclusion, we have shown that macroscopic Na current of a veratridine-treated cardiomyocyte can be quantitatively predicted on the assumption of a direct relationship between veratridine binding dynamics and Na current and as such can be successfully used to analyze molecular properties of the veratridine receptor site at the cardiac Na channel.

Animals↗
PubMed1992

Mutually exclusive action of cationic veratridine and cevadine at an intracellular site of the cardiac sodium channel.

Veratridine modification of Na current was examined in single dissociated ventricular myocytes from late-fetal rats by applying pulses to -30 mV for 50 ms every 2 or 5 s from a holding potential of -100 mV (20 degrees C) and measuring amplitude, Itail, and time constant, tau tail, of the post-repolarization inward tail current induced by the alkaloid. Increasing the pH of a 30 microM veratridine superfusate from 7.3 to 8.3 (which increases the fraction of uncharged veratridine molecules from 0.5 to 5% while decreasing that of protonated molecules from 99.5 to 95%) increased Itail by a factor of 2.5 +/- 0.5 (mean +/- SEM; n = 3). Switching from 100 microM veratridine superfusate at pH 7.3 to 10 microM at pH 8.3 did not affect the size of Itail (n = 4). Intracellular (pipette) application of 100 microM veratridine at pH 7.3 or 8.3 produced small Itail's suggesting transmembrane loss of alkaloid. If this was compensated for by simultaneous extracellular application of 100 microM veratridine at a pH identical to intracellular pH, Itail (measured relative to the maximum amplitude induced by a combination of 100 microM veratridine and 1 microM BDF 9145 in the same cell) at pHi 7.3 did not significantly differ from that at pHi 8.3 (84 +/- 4 vs. 70 +/- 6%; n = 3 each). Results from six control cells and five cells subjected to extra- and/or intracellularly increased viscosity by the addition of 0.5 or 1 molal sucrose showed that increasing intracellular viscosity 1.6- and 2.5-fold increased tau tail 1.5- and 2.3-fold, respectively, while a selective 2.5-fold increase of extracellular viscosity did not significantly affect tau tail.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Chiari malformation type I in a child with velopharyngeal insufficiency.

A five-year-old girl was referred for chronic and stable velopharyngeal insufficiency. Pharyngoplasty was performed, without significant improvement, and further neurological investigation was undertaken. Clinical examination and electromyography led to a suspicion of denervation of the IX, X and XI cranial nerves. Magnetic resonance imaging revealed a type 1 Chiari malformation.

Arnold-Chiari Malformation↗
PubMed1990

[Evoked potentials and the mode of cognitive development in boys 6 to 8 years of age presenting hyperactivity with attention deficit].

Event-related potentials were recorded in 2 groups (attention deficit hyperactivity disorder--ADHD--and normal controls) of 12 male children aged between 6-8 years during 4 categorization tasks. Each task was performed with a different type of visual stimulus; pictures, words, geometrical figures or digits. The amplitudes and latencies of a fronto-central P250 and a parieto-occipital P350 were examined. The overall amplitude of the fronto-central P250 was larger in the ADHD group. However, the overall latency of the parieto-occipital P350 decreased with age; coincidentally, in the control group, the P350 latency measured in the left hemisphere became shorter with age for the words than for the pictures. This was not the case in the ADHD group. These results are discussed in relation to the level of the orienting reaction and the modes (general or differentiated) of cognitive development.

Attention Deficit Disorder with Hyperactivity↗
PubMed1990

Subclinical alveolitis in immunological systemic disorders. Transition between health and disease?

A subclinical inflammatory alveolitis as assessed by BAL cell analysis may be present in a high proportion of symptomless patients with immunological systemic disorders and with normal chest roentgenogram. Subclinical alveolitis can be characterized by the relative proportions of the different cell populations comprising the alveolitis and by the activated state of the cells. Thus, subclinical alveolitis can be classified into two major groups: lymphocyte and neutrophil alveolitis. Lymphocyte alveolitis is frequently found in patients with extrathoracic granulomatosis (Crohn's disease, primary biliary cirrhosis, extrathoracic sarcoidosis) or with some collagen vascular diseases (Sjögren's syndrome, rheumatoid arthritis, systemic lupus erythematosus). Neutrophil alveolitis is a main finding in collagen vascular diseases, especially progressive systemic sclerosis, dermatopolymyositis and mixed connective tissue disease. In addition, alveolar macrophages may be spontaneously activated and release various mediators that could be relevant to the pathogenesis of interstitial lung disease. On the other hand, some other alveolar macrophage functions (antibacterial activity may be severely impaired in some diseases, for example systemic lupus erythematosus). Alveolar inflammation is associated with an increase in the permeability of the alveolar membrane responsible for an increased influx of blood proteins in the alveolar spaces. Although subclinical inflammation may also be detected by high resolution computed tomography (HRCT) scan and/or lung permeability scintigraphic studies, the significance and prognostic value remains unclear and clearly differs according to both the disease and the pattern of alveolitis.

Humans↗
PubMed1990

Interaction between DPI 201-106 enantiomers at the cardiac sodium channel.

The modification of cardiac sodium channels by DPI 201-106, its S-enantiomeric form (S)-DPI, and its R-enantiomeric form (R)-DPI was investigated with whole-cell voltage-clamp recording in single cultured ventricular myocytes obtained from late-fetal rats. From a holding potential of -100 mV, depolarizing pulses to -30 mV of 50-msec duration were applied at 0.2 Hz. Extracellular [Na] was reduced to 70 mM; temperature was 20 degrees. Drugs were administered directly on the cell by a double-barrelled microsuperfusion system. Sodium current inactivation was progressively slowed when the concentration of DPI 201-106 was increased from 0.3 to 3 microM. At 10 microM DPI 201-106, this effect was followed by a blocking effect on peak inward sodium current (INa), and at 30 microM inward sodium current was fully blocked within 2 min. The slowing of inactivation was produced by (S)-DPI (maximally effective at 3 microM), whereas (R)-DPI had little effect on inactivation at 3 microM. Conversely, (R)-DPI reduced INa at 10 microM, whereas (S)-DPI did not reduce INa at 3 microM. The effects of both (S)-DPI and (R)-DPI were partially reversed by washout. (R)-DPI retained its blocking activity on INa when the interval between depolarizing pulses was prolonged to 90 sec. In order to test whether the different sodium channel modifications produced by (S)-DPI and (R)-DPI were mutually exclusive, the INa-reducing activity of (R)-DPI was measured in the absence of (S)-DPI and after equilibration with a maximally effective (S)-DPI concentration. In the absence of (S)-DPI, 3 microM (R)-DPI reduced INa by 35% and in the presence of 3 microM (S)-DPI, by 51%. Thus, modification by (S)-DPI of sodium channels did not prevent their block by (R)-DPI. The INa-reducing activity of (R)-DPI was even significantly augmented by (S)-DPI after a 1-sec depolarization to -30 mV. During such prolonged pulses, (R)-DPI accelerated the monoexponential decay of the (S)-DPI-induced slow phase of sodium current inactivation. The results are consistent with an irreversible binding reaction between (R)-DPI and (S)-DPI-modified open sodium channels (association rate constant, 4.7 x 10(5) M-1sec-1). We conclude that (R)-DPI reduces INa by interacting both with resting sodium channels and with (S)-DPI-modified open sodium channels. The corresponding receptor site is stereoselective and distinct from and allosterically coupled to the (s)-DPI receptor that mediates slowing of inactivation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗