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Biomedical subjects

B Doyon

Publications and source records attributed to B Doyon.

36 records · Page 2Linked to original sources
PubMed1987

Levodopa-induced regional cerebral blood flow changes in normal volunteers and patients with Parkinson's disease. Lack of correlation with clinical or neuropsychological improvements.

Single photon emission computed tomography was used to measure regional cerebral blood flow in six normal subjects and 12 patients with Parkinson's disease, before and after acute oral administration of levodopa. The drug induced a significant increase in cerebral blood flow both in controls and patients. Before levodopa, there was no significant difference between the groups, either in flow values or in their pattern. The clinical effects of levodopa were not related to the hemodynamic changes. The results suggest that measuring the flow response to levodopa is not appropriate to demonstrate variations in central dopaminergic receptor sensitivity in man.

Administration, Oral↗
PubMed1986

Mortality from stroke in France 1968-1982.

Mortality data collected from 1968 to 1982 were screened in order to identify all death certificates listing stroke as underlying cause of death. Annual age- and sex-specific death rates were calculated using population data obtained from the 1968, 1975 and 1982 census of the French population. Data showed that stroke mortality has been declining by more than 30%, in most age groups both in men and women. There was a slight trend for this decline to be greater between 50 and 75 years of age in both sexes. A small increase was observed in women under 40 years of age. Large and stable variations in stroke mortality were found within France.

Adult↗
PubMed1983

[Industrial factors in the etiology of obstructive respiratory diseases. Implications for prevention].

The statistics of occupational diseases in industrial medicine, as well as the markedly elevated incidence of chronic bronchitis amongst workers, show that there is an additional respiratory risk linked to industrial environment and the conditions of work. Epidemiological studies in industry and in particular certain occupations, such as mining and the construction industry have led to a better understanding of this industrial risk as a generator of the additional obstructive respiratory disease occurring in exposed workers. Among the unrecognised risks is the prolonged exposure to the oxides of nitrogen which are capable of affecting gas exchange, as has been shown in one of our investigations in the production of nitrogenous fertilizers, which explains the mechanism. In industrial medicine, a preventative strategy should be planned, on the one hand considering individual risks and taking account of personal and genetic factors, on the other hand monitoring of respiratory risks by the identification of new irritants and finally the organisation of respiratory function screening for the early detection of lung dysfunction, by more sensitive tests than the FEV1 (VEMS), whose validity should be studied. The priority is primary prevention by the suppression of toxic irritants and by the improvement of working conditions.

Air Pollutants↗
PubMed1982

Statistical study of individual variations in sunburn sensitivity in 303 volunteers without photodermatosis.

Variations in individual sunburn sensitivity have been studied using erythema as the photobiologic criterion. The minimal erythema dose (MED), the minimal dose necessary to elicit an intense erythema (MED++), and an edema (MOD), were determined by Saidman's method. The irradiation was performed with a 2,500-W xenon arc solar simulator fitted with a water filter and WG 305 Schott filter. The high correlation between MED, MED++, and MOD and the existence of saturation phenomenon confirm that determination of MED is the best photobiologic criterion. The average MED and the pathologic threshold for total light spectrum irradiation are, respectively, 889 mJ/cm2 and 347 mJ/cm2. A statistically significant variation in MED as a function of age, sex, complexion, eye color, hair color, and Fitzpatrick skin type has been established. Finally, complexion has been shown to be the best clinical criterion for the characterization of sunburn sensitivity and a new classification of the epidermis for UV therapy and artificial photoprotection is proposed.

Adolescent↗
PubMed1981

Effects of traumatic manipulations on grafts, sutures, and host arteries during vascular surgery procedures. Experiments on dogs.

Scanning electron microscopy was used to diagnose incidents of trauma and the pattern of healing following surgical implantation of microporous blood vessel substitutes. Vascular reconstruction procedures using autogenous or synthetic prosthetic material inflict damage to the adjacent tissues as well as the prosthesis. This affects the thrombotic behavior and healing pattern of the area. The prognosis for long-term success are, as a consequence, directly influenced. Various vessel-occluding devices were evaluated in canine models with respect to their ability to damage blood vessels at the clamped site. The impact of suture needles on tissues and prosthetic materials was also considered. Of the various vessel-clamping devices which are commercially available, those which have elastomeric shields on the clamping components were found to be most satisfactory. The development of less traumatic surgical devices is discussed with the aim of further reducing surgical trauma.

Animals↗
PubMed1981

[Automatic measure of arterial pressure using the oscillometric method (Dynamap 845)].

The reproducibility and reliability of measurements performed with an automatic blood pressure measuring device based on the oscillometric method were assessed by comparison with the results obtained by the indirect auscultation using a mercury manometer. The results of the mean values, of the correlation between successive values and of the variation of the values of systolic and diastolic blood pressure show that the readings obtained by the automatic method are very reproducible.

Adult↗
PubMed1980

A SEM investigation of the trauma to prostheses and arteries during vascular reconstruction procedures.

Scanning electron microscopy was used to diagnose incidents of trauma and the pattern of healing following surgical implantation of microporous blood vessel substitutes. Vascular reconstruction procedures using autogenous or synthetic prosthetic materials inflict damage to the adjacent tissues as well as the prosthesis. This effects the thrombotic behavior and healing pattern of the area. The prognoses for long term success are, as a consequence, directly influenced. Various vessel occluding devices were evaluated on canine models with respect to their ability to damage blood vessels at the clamped site. The impact of suture needles on tissues and prosthetic materials was also considered. Of the various vessel clamping devices which are commercially available, those which have elastomeric shields on the clamping components were found to be the most satisfactory. The development of less traumatic surgical devices and possible modifications in the surgical protocols are discussed with the aim of further reducing surgical trauma.

Animals↗
PubMed1979

[Physiological variations of arterial pressure and heart rate in the first 5 minutes after moving from a supine to an upright position].

The physiological variations of blood pressure and heart rate were studied in the first five minutes of orthostatism in conditions identical to those encountered in clinical medicine. An increase in heart rate and diastolic blood pressure was observed from the first minute. The value of systolic blood pressure decreased as the subject got up and then rose to the value measured when lying down. At the fourth and fifth minute the three parameters were stable at significantly higher values than observed when lying down for the heart rate and diastolic blood pressure, but at an identical level for the systolic blood pressure. This study shows the necessity of measuring the orthostatic blood pressure using a precise technique which detects postural abnormalities when measured in the minute of orthostatism and which gives an assessment of the standing blood pressure when measured at the fifth minute.

Adult↗
PubMed1979

[Evaluation of an automatic device for arterial blood pressure determination : the Arteriosonde 1217].

The reproductibility and reliability of measurements made with an automatic device for measuring blood pressure was assessed with reference to the results obtained by indirect auscultation with a mercury manometer. The results of the study of the average values of the correlation between successive values, and of the variability of the values of the systolic and diastolic blood pressure show that the measurement obtained by this method are very reproducible.

Adult↗
PubMed1978

[Reproducibility of measurements of arterial pressure and heart rate during exercise test: its significance and application].

The authors report their findings from a study of the reproductibility of measurements of blood pressure and heart rate both at rest and during exercise (work on a bicycle ergometer) in 19 patients who were tested on two occasions with a mean interval of 9.8 days. A study of the correlations, of variability, and of the findings on applying Student's "t" test, have led us to the conclusion that these parameters are more reproduceable on exercise than at rest, and become increasingly reproduceable as exercise increases. These conclusions support the use of an induced hypertension test under exercise.

Adult↗
PubMed1975

Ventricular compliance and ageing.

Compliance of the right ventricle has been studied in 29 aged subjects who were free from any overt heart failure. The observations indicate that a loss of ventricular compliance results, in aged subjects, in an impairment of diastolic filling, which itself is responsible for a reduction in cardiac output. However, there appears to be no relationship between ventricular compliance and systolic performance but the failure to find any such relation may be due to a contractile adaptation in subjects having a low ventricular compliance.

Adaptation, Physiological↗
PubMedDate not supplied

Comparative study of natural autoantibodies in the serum and cerebrospinal fluid of normal individuals and patients with multiple sclerosis and other neurological diseases.

Using a panel of antigens (actin, myosin, tubulin, albumin, transferrin, peroxidase, thyroglobulin, DNA, prolactin, TNP and myelin basic protein (MBP], we have tested the antibody activity of serum and cerebrospinal fluid (CSF) from healthy individuals, patients with multiple sclerosis (MS) and individuals with other neurological diseases. No differences in the concentrations and specificities of the serum antibodies were observed among the 3 groups. In contrast, we found that MS patients often had elevated CSF antibody levels against many antigens of the panel. The MS patients with local immunoglobulin production in the central nervous system (CNS) had the highest antibody levels. Restricted antibody activity against a given antigen of the panel was not observed. Compared to the two other groups, the MS group had equivalent titres of anti-MBP antibodies in the CSF. These results suggest that, in MS, a general immune dysregulation exists which leads to a local expansion of B lymphocytes producing autoantibodies with reactivities similar to those of serum natural autoantibodies.

Antibody Specificity↗