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Biomedical subjects

D Lacroix

Publications and source records attributed to D Lacroix.

103 records · Page 6Linked to original sources
PubMed1988

Electrophysiological effects of methylphenidate on the coeruleo-cortical noradrenergic system in the rat.

The effect of methylphenidate on noradrenergic neurotransmission was investigated in urethane-anesthetized rats. The spontaneous activity of locus coeruleus noradrenergic neurons was the same in rats treated for 7 days with methylphenidate as in the controls. In control rats, i.v. methylphenidate induced a reduction of locus coeruleus neuronal firing whereas in rats treated for 7 days with methylphenidate, the same dose of methylphenidate failed to induce any change in locus coeruleus activity. At this time, clonidine induced a lesser reduction of locus coeruleus neuronal firing than in the controls, indicating that their autoreceptors had become desensitized. Following electrical stimulation of the locus coeruleus, most of the spontaneously firing cortical neurons were inhibited but the percentage of such neurons was reduced and the neurons showed a decreased responsiveness after methylphenidate treatment. The responsiveness of cortical neurons to microiontophoretic applications of NA as assessed by the I.T50 method was reduced after 7 days of treatment with methylphenidate. These findings suggest that the efficacy of cortical NA neurotransmission is markedly reduced following methylphenidate treatment.

Animals↗
PubMed1988

[New inotropic drugs in chronic cardiac insufficiency: progress or wrong track].

The first results of the long-term treatment of chronic heart failure with inotrope positive medications are disappointing, especially in that survival is not prolonged and even a greater mortality is suggested. Is it because of the regular failure of specific medications, of a class of medications or because the overall concept of inotropism stimulation during chronic heart failure should be condemned? The mechanisms of inotropism of normal muscles or muscles in human chronic heart failure are reviewed as well as the various pharmacological means available to stimulate inotropism.

Cardiotonic Agents↗
PubMed1988

[Late ventricular potentials. Clinical applications and relation to severe ventricular arrhythmias].

The recording of late ventricular potentials with high amplification cardiography (HAC) permits to identify patients presenting a risk of sudden death and ventricular tachycardia, especially in the later stage of myocardial infarction. Few authors have studied the prevalence of these potentials in other heart diseases presenting a risk of sudden death. Most series in the literature are too small to specify variations in the prevalence of these potentials according to the severity of the coronary disease. For this purpose, 835 patients including 535 coronary patients were evaluated with HAC compared to data from coronary angiography and Holter test. An automatic quantification method of the late potentials was used on 131 healthy subjects. The prevalence of late potentials is 32 p. cent after infarction, and 75 p. cent when a chronic ventricular tachycardia is present. These potentials retain their significance of tracers of ventricular arrhythmias in primary dilated myocardiopathies, with a prevalence of 25 p. cent reaching 50 p. cent in case of ventricular tachycardia. Their recording in the presence of idiopathic ventricular extrasystoles must be an indication to look for an underlying cardiopathy. It is possible to record them in other diseases especially in advanced valvular cardiopathies, as well as in right ventricular dysplasias with arrhythmia where their presence has a great diagnostic value.

Arrhythmias, Cardiac↗
PubMed1987

[Raynaud's phenomenon and finger necrosis after treatment of ovarian seminoma with bleomycin, vinblastine and 5-fluorouracil].

Bleomycin is sometimes at the origin of a Raynaud's phenomenon (RP). From the literature, there does not seem to exist a dose-dependent relationship. The phenomenon occurs early or late and often is resistant to various medications. The possible physiopathological mechanisms are: direct vascular toxicity, hypersensitivity vascularization, alteration of platelets activity, alteration of Willebrand's factor, and as predisposing factors: association to periwinkle alkaloids or hypomagnesemia.

Adult↗
PubMed1987

[Prevalence of late potentials in ventricular tachycardias. Comparison with a control group].

High amplification electrocardiographic recording of ventricular late potentials was introduced a few years ago and seems to be a simple, reliable and reproducible method to identify patients at a high risk of sudden death and ventricular tachycardia, principally during the chronic phase of myocardial infarction. However, few authors have studied quantitatively the prevalence of late potentials in patients with ventricular tachycardia compared with a sufficiently large sample of healthy subjects. In this study 34 patients with sustained ventricular tachycardia (11 women, 23 men, mean age 58 years) and 131 healthy subjects (29 women, 102 men, mean age 29 years) underwent high amplification time-averaged ECG recording, and an algorithmic analysis of the tracings was conducted, using the Simson method. Three numeric parameters were used in the interpretation of the tracings: HFRMSA = mean RMS amplitude of the last 40 milliseconds of QRS; HFD40 = delay in signal decrease from amplitude 40 mu v to baseline, and delta QRS = difference in QRS duration with 0-250 Hz and 25-250 Hz filterings. Normal values, as determined from measurements in healthy subjects, were: HFRMSA above 27 mu v, HFD40 below 35 ms and delta QRS below 13 ms. Late potentials were present when at least one of these criteria was positive. When these norms were applied to patients with sustained ventricular tachycardia the prevalence of late potentials was 76%, rising to 90.4% in the subgroup of 21 patients with coronary disease. With the method thus defined the specificity for each criterion taken separately is 97.5%. According to the norms, only one control subject (0.8%) gave a false-positive result.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1979

Primary and secondary prevention of alcoholism: emerging trends and research strategy.

1. The theoretical and empirical value of a "level conceptualization in prevention" as proposed by the classical 'public health' model is challenged. 2. Although prevention should be related only to reduction of incidence of the disease (new cases), for various reasons the authors also include secondary prevention in the prevention of alcoholism. 3. Two main strategies are proposed in the prevention of alcoholism: (a) the global prevention directed to the population at large, and (b) the oriented or selective prevention directed to specific target groups (high risk groups). 4. In primary prevention a theoretical model, based on system theory "the ecogenetic wheel model" is proposed which tries to integrate the multidimensional (dependent variables), multifactorial and family approaches (independent variables) involved in alcoholic-related problems. 5. The biological predictors (chromosomal and biochemical markers) and psychological predictors to be used in the early detection of alcoholism are discussed. 6. Two theories are suggested for detection of biochemical markers: direct detection in naive subjects and indirect detection (activating theory) in subjects exposed to ethanol. 7. Secondary prevention could presently benefit from a "constellation" of clearly identified biological markers which would allow for the early detection of initial alcoholics. Screening programs could be implemented for selected target groups such as (a) occupational alcoholism programs, (b) programs for alcoholics' families, (c) programs for specific hospitalized patients and (d) alcohol programs related to traffic accidents.

Alcoholism↗
PubMed1979

Genetic epidemiology and the prevention of functional mental disorders and alcoholism: family study and biological predictors.

1. This review intends to present some theoretical and practical considerations which appear essential for the development of rational research strategies in the field of primary and secondary prevention of mental disorders and alcoholism. 2. The various advances and trends regarding the nosology and diagnosis of these disorders are discussed. Integrative epidemiological models for relating the multifactorial causation and the heterogeneity (multidimensionality) of these disorders are presented. 3. It is emphasized that alcoholism and the functional mental disorders occur in families as shown by (i) the increased incidence of these disorders among relatives and (ii) the existence of various clinical categories genetically associated. 4. Current methodology in clinical diagnosis and genetic epidemiology represent powerful procedures for typing and subtyping of these disorders. Family studies could identify more homogeneous subgroups and generate hypotheses as to the mode of transmission of mental disorders and alcoholism. 5. Real progress could be made in prevention only if the search for predictors is carried out in homogeneous subgroups. 6. There is a lack of knowledge regarding biological predictors. An urgent need for association studies and linkage analysis should be carried out in order to identify genetic markers (causal relationship) and chromosomal markers. These could provide for the specification of a constellation of markers and the development of appropriate tests to identify subjects at risk likely to develop alcoholism and mental disorders. 7. The immediate issues in secondary prevention and the later outcomes in primary prevention are outlined.

Alcoholism↗
PubMed1976

[Phonation following reconstructive laryngectomy].

The authors describe the results obtained, from the point of view of vocal function in 43 cases of patients who underwent various types of reconstructive laryngectomy: trachio-hyoido-epiglotto-pexy (Arslan and Serafini), crico-hyoido-pexy (Labayle), crico-hyoido-epiglotto-pexy (J.J.Piquet). These operations have as their main aim the preservation of vocal function, for social particularly as it is, increasingly, young people who are affected. The survey was carried out by means of measurement of volume, sonagraph recordings, recordings of movements of the neoglottis by accelerometer and integrating amplification. This method makes it possible to classify voices more objectively. The survey shows the importance of surgical methods and the prime importance of post-operative orthophonic re-education; results have proved very satisfactory three to six months after the operation.

Deglutition↗