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Biomedical subjects

J Caron

Publications and source records attributed to J Caron.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Validation of Satisfaction with Life Domains Scale in Quebec].

This article presents the results of the Quebec validation of the Satisfaction With Life Domains Scale: This scale was developed in the United States for the general population and adapted for severely mentally ill individuals. Two hundred and sixty six individuals from the general population and 245 severely mentally ill persons participated in this study. Factor analysis allowed the identification of four sub-scales for the clinical population and five for the general population. The scale (alpha = 0.90) and the sub-scales (alpha between 0.60 et 0.84) show excellent internal consistencies and the test-retest reliability was good (r = 0.73). Moreover, analysis of the variance and the discriminant analysis allow to acknowledge that the sub-scales have a high discriminating power; they allow to distinguish the general population from welfare recipient and people suffering from psychosis. The overall results suggest that l'Echelle de satisfaction des domaines de vie have good psychometric properties and can be considered as a valid instrument for assessing subjective quality of life in descriptive or evaluative studies.

Analysis of Variance↗
PubMed1996

[The scale of social provisions: their validation in Quebec].

This article presents the results of the Quebec validation of the Social Provisions Scale (Cutrona et Russell, 1989). L'échelle de provision sociales was administered to 790 people on the course of two studies. The first one included 387 university students of first level and the second was realized with 266 people from the general population, 79 welfare recipients and 58 persons with a diagnosis related to psychosis. The results show that the scale presents a good internal coherence and a satisfying temporal stability, thus assuring the fidelity of the instrument. The factorial analyses have not reproduced exactly the same profile as the original instrument, however the moderate correlations between the different social provisions sustain the validity of the multidimensional construct of social support. Moreover, analyses of the variance and the discriminating analysis allow to acknowledge that the sub-scales have a high discriminating power; they allow to distinguish the general population from welfare recipients and people suffering from psychosis. Finally, norms are presented for the general population.

Humans↗
PubMed1995

[Suicide in Abitibi-Témiscamingue: epidemiologic studies for 1986-1991].

A permanent register on suicide cases was created and has produced a quantitative description of suicide in Abitibi-Temiscamingue over the period 1986-1991. This study reviews 218 suicide cases reported by the Coroner's Office of Quebec. A content analysis grid was applied on the Coroner's files and has facilitated the study of 87 variables potentially related to suicide. The results present the evolution of the suicide rates in this region in relation to those of other parts of Quebec, and the differences between parts of the region. Many variables were related to suicide (age, gender, urban setting, methods, suicide sites, seasons, etc.). A review of recent literature on suicide throughout the world indicates that patterns of suicide in Abitibi-Temiscamingue follow trends in North America with certain differences.

Adolescent↗
PubMed1994

Regulation of rns, a positive regulatory factor for pili of enterotoxigenic Escherichia coli.

Attachment of enterotoxigenic Escherichia coli to the human gut is considered an important early step in infection that leads to diarrhea. This attachment is mediated by pili, which belong to a limited number of serologically distinguishable types. Many of these pili require the product of rns, or a closely related gene, for their expression. We have located the major promoter for rns and found that although its sequence diverges significantly from a sigma-70 promoter consensus sequence, it is very strong. Transcription of rns is negatively regulated both at a region upstream of this promoter and at a region internal to the rns open reading frame. In addition, rns positively regulates its own transcription, probably by counteracting these two negative effects.

Base Sequence↗
PubMed1993

Acute electrophysiological effects of intravenous milnacipran, a new antidepressant agent.

Milnacipran is a new antidepressant agent selected from a series of cycloproprane derivatives. The aim of this study was to investigate the acute electrophysiological effects and the tolerance of intravenous administration of this drug in 10 patients without any abnormality as shown in an electrophysiological study done for various complaints. Milnacipran was given over a 30-min period at doses of 0.2 mg/kg (2 patients), 0.4 mg/kg (2 patients) and 0.8 mg/kg (6 patients). The most significant alterations observed in this study were increases in heart rate (average of maximal increase: +19.5% at 50 min, P = 0.06) and systolic blood pressure (average of maximal increase: +21.5% at 10 min, P < 0.005), and decreases in the functional refractory period of the atrium (-3%, P < 0.05), the atrioventricular node (-9%, P < 0.005) and the effective refractory period of the right ventricle (-10.8%, P < 0.05) at 50 min. The sinus node function was improved in nine patients but depressed in one patient with previous slight baseline sinus node alterations. Milnacipran being devoid of both anticholinergic and monoamine oxidase inhibition activities, these alterations could be related to inhibition of noradrenaline uptake leading to an increase of adrenergic activities. No other ECG or electrophysiological parameters were significantly altered. Five of the 10 patients reported transient nausea, four of them for the highest dosage (0.8 mg/kg) and at the moment of peak of milnacipran plasma level. In conclusion, electrophysiological effects of intravenous milnacipran are negligible. These findings differ from those, well described in the literature, for imipramine-like antidepressant agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Effects of acute and chronic administration of acebutolol on the right ventricular effective refractory period in conscious dogs.

beta-Adrenergic blocking drugs are effective in reducing sudden cardiac death after acute myocardial infarction but the precise mechanism of this effect is unclear. We investigated the acute and chronic effects of acebutolol, a beta-adrenergic blocker, on electrocardiographic parameters, diastolic excitability threshold (DET), and right ventricular effective refractory period (RVERP) in chronically instrumented conscious dogs. These parameters were determined during spontaneous sinus rhythm and at a fixed pacing rate (200 beats/min). Acebutolol (0.5, 1, and 5 mg/kg i.v.) decreased the heart rate (HR) (by 23, 26, and 24%, respectively) without effects on any electrocardiographic parameters or on the DET. The maximal increases in ERP were 4.7, 7, and 7.8%, respectively, during pacing and 8.5, 13.3, and 10.3%, respectively, during sinus rhythm. Acebutolol, 10 mg/kg/day P.O. for 6 weeks, reduced the HR from the third day onward without altering the PR, QRS, QT, or QTc intervals or the DET. The increase in ERP was significant from the third day (14%) during pacing and from the seventh day (15.5%) during sinus rhythm. The degree of prolongation of the ERP subsequently remained stable during the 6 weeks of treatment. The ERP returned to the baseline value 7 days after acebutolol withdrawal. This increase in ERP, which was more marked during chronic oral treatment, could contribute to the documented protective effect of the beta-blocking drugs against sudden cardiac death after myocardial infarction.

Acebutolol↗
PubMed1993

Roles of LH and insulin resistance in lean and obese polycystic ovary syndrome.

OBJECTIVE: The relationship between insulin resistance and hyperandrogenism led us to study insulin resistance in polycystic ovary syndrome (PCOS) in order to determine its prevalence and pathogenesis. DESIGN: Blood samples were taken on the 8th day after menses commenced. PATIENTS: Sixty-one women with PCOS, 30 with normal weight (BMI < 25 kg/m2) (group 1) and 31 with obesity (BMI > 26 kg/m2) (group 2) were studied. They were divided also according to LH level: group A, low or normal LH (n = 23) and group B, high LH (n = 38). Twenty lean control women and 16 obese control women were studied. MEASUREMENTS: Serum LH, testosterone, free testosterone, dehydroepiandrosterone, sex-hormone binding globulin, androstenedione, and fasting insulin were measured. Insulin sensitivity was explored by the insulin tolerance test (ITT). ITT was performed by bolus i.v. insulin of 0.1 IU/kg. Blood glucose was measured before (-5,0) and after injection (3, 5, 7, 10, 15 minutes). Insulin sensitivity was given by the ratio of glycaemic variation to initial blood glucose (delta G/G index). RESULTS: delta G/G was correlated with other insulin resistance parameters, particularly fasting insulin r = 0.40, P < 0.01. The PCOS groups had the following insulin resistances (mean +/- SEM) compared to matched groups: delta G/G lean PCOS vs lead controls: 0.45 +/- 0.02 vs 0.61 +/- 0.01, P < 0.001; delta G/G obese PCOS vs obese controls: 0.32 +/- 0.02 vs 0.40 +/- 0.01, P < 0.02. Insulin resistance was higher in group A than in group B: delta G/G 0.29 +/- 0.02 vs 0.45 +/- 0.02, P < 0.001. The prevalence of insulin resistance was 63% in lean PCOS and 51% in obese PCOS. Positive correlations between delta G/G index and LH were found in group 1 and 2, respectively r = 0.45, P < 0.01 and r = 0.55, P < 0.01. CONCLUSION: PCOS was associated with a significant decrease of insulin sensitivity, independent of obesity. The correlation between LH and insulin sensitivity suggests a complementary action in PCOS.

Adolescent↗
PubMed1993

[Transient severe orthostatic hypotension and hematoma of the pontine tegmentum].

A 57-year old patient presented with a posterior pontine hematoma and severe postural hypotension. The lesions were localized in the pontine tegmentum. They were bilateral and involved the area of the nucleus reticularis pontis caudalis, left medial lemniscus and roots of several cranial nerves, especially the VIth. The patient had lasting postural hypotension, with reduction of the physiological tachycardia. Investigation of heart rate regulation during manoeuvres however revealed that the accelerating reaction partially persisted, especially with Valsalva manoeuvre. Heart rate recording for 24 hours showed that the physiological nocturnal slowing down reaction had disappeared. In the following months, progressive but limited recovery of blood pressure regulation and accelerating reactions was observed.

Blood Pressure↗
PubMed1993

[Bulbar hematoma of the olivary area. An analysis of the autonomic syndrome].

The consequences of an anterolateral medullary hematoma in a 50 year old patient are reported. The lesions principally involved the inferior olive nuclei, the lateral reticular nucleus, and, partially, the nucleus ambiguus. Long-lasting postural control deficit and hypotonia were observed, associated with alpha motoneurons hyperexcitability. Analysis of the heart rate regulation showed a severe reduction of the normal accelerating reactions and a relative preservation of slowing down reactions that suggested a deficit of the ortho-sympathetic control. Unilateral palsy of the tongue and pharynx was also observed without sensory or sensorial deficit. The long term course was favourable.

Autonomic Nervous System Diseases↗
PubMed1992

High-performance liquid chromatographic assay for amiodarone N-deethylation in microsomes of rat liver.

A reversed-phase high-performance liquid chromatographic assay using ultraviolet detection is described for determining the production of the major N-dealkylated metabolite of amiodarone in rat liver microsomes. The principal advantages of this method are its simple sample preparation (protein precipitation by acetonitrile), low detection limit for N-desethylamiodarone (0.05 mumol/l) and relatively short analysis time (16 min). Its analytical applicability is demonstrated by the comparison of the kinetic parameters (maximum velocity and Michaelis-Menten constant) between Sprague-Dawley and Dark-Agouti rats.

Amiodarone↗
PubMed1992

[Role of adrenocortical scintigraphy in the exploration of incidentally discovered tumors].

To determine the utility of adrenocortical scintigraphy with I131-6 beta-iodomethyl-19-nor-cholesterol (NP59) in incidentally discovered adrenal masses, we studied 12 patients with a unilateral adrenal mass and without other primary tumors or signs of pheochromocytoma or hyperfunctioning adenoma. Ten patients had an adenoma (size: 12 to 35 mm), the diagnosis was made by surgery or by no change in size on repeated CT scans. The NP59 scintigraphy showed an increased uptake on the side of the tumor in 8 cases with a decreased uptake of contra-lateral gland in 7 cases. Hormonal investigations of glucocorticoid function suggested supranormal or fluctuant cortisol secretion in 5 cases as assessed by moderately elevated urinary free cortisol or by incomplete dexamethasone suppression test. These abnormalities disappeared after surgery. Two patients had normal bilateral uptake of NP59, the sizes of the tumors were 12 and 20 mm. Two patients had an extra-adrenal tumor. The NP59 scintigraphy showed a moderately decreased uptake on the side of the hematoma of one patient and a compression of the normal adrenal by ganglioneuroma of the other patient. Our results and those of other authors suggest that positive NP59 scintigraphy could confirm the cortical nature of an incidentally discovered adrenal mass, probably an adenoma that must be followed up morphologically and functionally. No uptake by a tumor greater than 2 cm suggests a primary malignancy or extra-adrenal origin which must be diagnosed by invasive methods.

Adenoma↗
PubMed1992

Pheochromocytoma: a frequent indicator for MEN 2.

Pheochromocytoma is a frequent indicator of multiple endocrine neoplasia type 2A (MEN 2A); in the 35 French MEN 2A families in which a pheochromocytoma occurred first in some affected members, 30% of the patients had a pheochromocytoma as the first manifestation constituting 45% of all patients with pheochromocytomas. The finding of a pheochromocytoma is a strong indication for a search for medullary thyroid carcinoma and for initiating family screening.

Adrenal Gland Neoplasms↗
PubMed1991

Single-dose quinidine treatment inhibits mexiletine oxidation in extensive metabolizers of debrisoquine.

Urinary elimination of unchanged mexiletine, p-hydroxymexiletine (PHM), hydroxymethylmexiletine (HMM) and mexiletine N-glucuronide conjugate (MGC) was investigated before and after treatment with quinidine. All subjects were phenotyped as extensive metabolizers for debrisoquine oxidation. The total recovery of mexiletine and metabolites was significantly reduced after quinidine pretreatment. It is concluded that pretreatment with a very low dose of quinidine inhibits markedly the elimination of both major mexiletine metabolites (PHM and HMM) and likely decreases the overall elimination of mexiletine. That should lead to changes in mexiletine disposition and have clinical consequences during combination therapy with both drugs.

Debrisoquin↗
PubMed1991

High permanent plasma adrenaline levels: a marker of adrenal medullary disease in medullary thyroid carcinoma.

Increases in urinary, plasma and tumour adrenaline have been previously observed in MEN II patients with phaeochromocytoma. However, the sensitivity of adrenaline for early detection of adrenal medullary disease has not been accurately evaluated. Twenty-five patients with medullary thyroid carcinoma (MTC) histologically confirmed but without clinical or biological evidence of phaeochromocytoma have been studied. Medullary adrenal status was evaluated by adrenal CT-scan. MIBG scintigraphy, determination of urinary VMA, metanephrines and total catecholamine levels, measurement of nyctohemeral plasma adrenaline or noradrenaline concentrations (every 2 h during 24 h) and clonidine suppression test. Four of the 25 patients had evidence of adrenal medullary disease in view of the coexistence of CT-scan, MIBG scintigraphy and plasma adrenaline abnormalities. Moderate adrenal enlargement (unilateral, n = 3; bilateral, n = 1) was observed on scans together with a high adrenal MIBG uptake (bilateral, n = 4). Among the urinary parameters studied, a minor MN increase was observed in only one of the four patients. Plasma adrenaline levels were significantly (P less than 0.01) different from those of the other 21 patients (mean + SD 115 + 110 pmol/l). This plasma adrenaline increase is reproducible and not suppressed by clonidine. Unilateral adrenalectomy performed in one patient confirmed a phaeochromocytoma and induced normalization of plasma adrenaline levels. In contrast, the plasma noradrenaline levels of the four patients were not statistically different from those of the other 21 patients. These data suggest that persistent high plasma adrenaline levels may be selectively increased in MTC patients together with a moderate adrenal CT-scan enlargement and a high adrenal MIBG uptake, despite a normal urinary excretion of total catecholamines and catecholamines metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Gland Neoplasms↗
PubMed1991

Wenckebach periods in sinoatrial block: experimental and clinical evidence.

The reality of sinoatrial Wenckebach periods (WP) has been suggested, but not proven, in the literature. We report experimental and clinical data showing WP in sinoatrial blocks. Experimental sinoatrial blocks were induced by superfusion of bepridil (10(-5) M) in 15 preparations of isolated rabbit right atria. Different types of block were observed, including Blumberger I block, i.e., sinoatrial WP. The recordings showed that the typical pattern of Blumberger type IA block and sinoatrial WP may be due to transient acceleration of the sinus rate, without change in the increment. We also observed sinoatrial WP in a 72-year-old patient on direct recordings of the sinus node (SN) electrical activity. In this case, transient acceleration of the sinus rate also seemed to be involved in the genesis of sinoatrial WP. Analysis of these clinical and experimental data showed similarities that may explain the mechanism of the WP. Usually type IA Blumberger block is said to involve a decrease in the sinoatrial increment to explain the atrial sequence (decrease in PP interval followed by a pause shorter than twice the value of the preceding cycle, then a cycle longer than the one preceding the pause). In fact, this pattern can be observed when the acceleration of the higher structure, the SN, induces block within the lower structure, i.e., the atrium.

Action Potentials↗
PubMed1991

[Prolongation of the CAST study.Is it justified to consider another trial?].

A possible prolongation of the CAST would be another trial of the same type, (CAST II), designed for high risk patients (1 year mortality over 20%). The aim of this study would be to confirm the hypothesis that the ratio efficacy/undesirable side effects of antiarrhythmic drugs is beneficial in this type of patient. The most important selection criteria would be an ejection fraction of less than 40%, the presence of repetitive arrhythmias, especially ventricular tachycardia on Holter monitoring and the recording of late ventricular potentials on surface averaging ECG. The patients would be included at about the 20th day after myocardial infarction in order to exclude as much as possible unstable coronary artery disease and ventricular arrhythmias on successive Holter recordings because this would make interpretation of the efficacy of antiarrhythmic drugs impossible. The ideal number of patients would be about 5,000 but this is unrealistic because the trial would only include high risk cases and there would be difficulties in recruiting this number even in a multicenter trial. During follow-up of 2 to 3 years, the surveillance of the therapeutic efficacy of the antiarrhythmics would have to be better than in the CAST. The most delicate methodological problem would be the randomization of patients as the formation of a placebo group is unethical in high risk coronary patients with severe or malignant ventricular arrhythmias. The use of the only proved cardioprotector drugs, the betablockers, in all these high risk patients would be one solution, even if it might introduce a bias in the results.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗