Biomedical subjects
G Nicolas
Publications and source records attributed to G Nicolas.
[The heart and drug poisoning, excluding cardiologic treatments].
When considered strictly from the viewpoint of actions on the myocardium, the number of drugs falling into this category is limited, but the resulting conditions may be serious. The prototype for cardiac toxicity is the group of antimitotic drugs (adriamycin or daunomycin). If these drugs are used; frequent and careful follow-up is necessary, the dosage at which the drug becomes cumulative must be known; and patients with a pre-existing cardiac condition must be exluded from treatment. Above all, it is essential not to wait until asystole occurs, but to try to prevent such occurrences by monitoring the patient electrocardiographically. A part from these drugs, recent articles in the literature suggest that similar care should be taken when prescribing emetine and lithium salts. There is insufficient information about other drugs which may have a certain degree of cardiotoxicity. For this reason, it is most important to gather information on accidents and reaction during treatment.
[Rapid freezing of biologic tissue. Measurement of temperature and rate of freezing by thin-layer thermocouple].
An apparatus for rapid freezing of biological tissues by contact with a copper block cooled by liquid helium has been devised to reduce the contamination of copper block surface. It prevents the precooling of the specimen while going through the layers of cold helium gas surrounding the copper block and reduces the quantity of helium necessary for freezing. It also enables one to obtain easily reproducible results from freezing by immersion in liquid coolants. Freezing rates are measured directly, related to the specimen thickness, by a thin film thermocouple; its low thermal inertia gives speed measurements of the order of 100,000 degrees C/s.
[Study of magnesium level in myocardium and aorta tissues from subjects free of ishemic necrosis (author's transl)].
Before carrying out a study on the levels of magnesium in the myocardium and the aorta in subjects who had died of coronary thrombosis, we determined the reference levels of magnesium in the right and left ventricles and in the aorta of sixteen normal subjects. The samples were homogenized and digested with nitric acid/hydrochloric acid mixture before the measurement itself was made; this was carried out by atomic absorption spectrophotometry. The magnesium values are expressed in microng/g of wet tissue, in mg/g of tissular proteins, in mg/ of total lipids in the aortic wall. The differences between the concentrations of proteins or magnesium in the left and right ventricles are significant magnesium in the left and right ventricles are significant (P less than 0,001). They probably derive from anatomic and physiological differences. We have found a correlation which is significantly positive between magnesium level and protein level in the ventricle. In the aorta, the results for proteins, lipids and magnesium are extremely dispersed because of the heterogeneous nature of biochemical composition of this tissue according to age and area which it has been taken from.
[Endomyocardial biopsy: its value in tropical pathology. Apropos of 3 new cases].
The authors report their experience with three endomyocardial biopsies in cases of endomyocardial fibrosis; two of them were successful. The light and electron microscopical changes found were of two types: one showed the classical appearances of pure fibrosis, which was acellular and associated with degenerative changes in the heart muscle cell; the other type consisted of young fibrous tissue with numerous fibroblasts secreting a copious fibrillary substance which may have been the precursor of collagen fibres. Endomyocardial biopsy is, in experienced hand, a useful means of diagnosis in the field of tropical heart disease: it can be helpful in diagnosis, provided that the biopsy site is carefully controlled by anteriography and cathereisation; additionally, the opportunity to study the histological and electron microscopical changes which this technique affords should lead to a better understanding of the pathogenesis of those tropical cardiac disorders whose aetiology is yet to be established.
[Study of the association between aortic coarctation and congenital mitral insufficiency (excluding atrioventricular canals)].
Coarctation of the aorta is accompanied by congenital mitral incompetence in 3% of cases, and this combination worsens the prognosis. A series of 23 cases is reported, and the treatment analysed. In 6 cases only medical treatment was used, either because death was rapid or, on the contrary, satisfactory progress made it possible to wait for the normal age for resection and suture of the coarctation. In one case the severity of the mitral incompetence required early valvular replacement, while the minimal coarctation was ignored. Usually (16 cases) a Crafoord operation is carried out as a first stage, and of the 13 children still alive, 8 had their mitral incompetence improved or stabilised; but in 5 it became worse, requiring mitral valve surgery from 1 to 7 years later. Post mortem study showed the multiplicity of mitral lesions present, and explains the difficulty of mitral 'plasty' operations, which are the best solution in children.
[Complete atrio-ventricular dissociation in generalized scleroderma].
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[Cryofractures of biological material performed at very low temperatures in ultravacuum].
A new instrument has been designed for freeze-fracturing of biological material in ultra high vacuum. Complementary replicas of the freeze-fracture faces can be done at a temperature reaching to --260 degrees C in a short time, without any contamination of fracture faces being observed.
[Problems posed by anesthesia in the hypertensive treated with beta-blockaders].
The use of beta-blocking agents against hypertension and their rapid extension in daily practice we have to consider the problem of anesthesia of a patient undergoing such treatment. Continuation of the treatment increases the operative risk, discontinuation long before the operation leaves the hypertension to reappear and discontinuation 48 hours before may lead to a coronary or arrhythmic accident. Therefore, except in case of emergency, treatment may be maintained until the day before the operation, and in case or emergency extensive atropinisation is desirable. Finally prescription of selective beta-blocking agents decreases the risks.
[Myocardial biopsy in congestive myocardiopathies of apparently primary origin].
38 patients with congestive cardiomyopathy of apparantly primary origin had a myocardial biopsy. The histology of the fragment of myocardium was studied both by light microscopy and electron microscopy. The results were compared with those from 3 "control" cases and with 16 cases of congestive asystole secondary to a known cause. The non-specific patternss which were observed were of 3 types: patterns of degeneration, pattern of hypertrophy, and interstitial fibrosis. Chronic alcholism had no modifying effect on the ultrastructure. Finally, the group in which the morphology was altered had a higher mortality, but the prognostic significance of the degree of severity of the morphological change must be treated with caution in each individual case.
[Phonomechanograms of patients with the Bjork aortic valve prosthesis].
A survey, with consecutive phonocardiograms, of the function of 75 Björk aortic valve prostheses has enabled us to examine the basic components of the opening and closure sounds of this type of replacement; these are usually made up of multiple components in varying combinations. This diversity underlies the importance of an early postoperative recording to act as a baseline. In addition, 2 cases of malfunction presented with only the classical phonocardiographic changes.
[Endomyocardial biopsy. Innocuousness and clinical value. A 5-year experience].
The authors present their experience of the endomyocardaial biopsy procedure by Konno's technique; they have carried out 180 biopsies in 94 subjects. When the person taking the biopsy is experienced, the procedure is trouble-free, and yields tissue fragments of good quality which are suitable both for histological study and for study of ultrastructure. Biopsies from 47 cases of primary congestive cardiomyopathy have formed the basis of a precise histological study, and have been compared with the findings of a control group comprising various cardiac defects and three normal hearts. The diagnostic and prognostic value of the method are discussed.
[Phase morphometric differences among Locusta migratoria cinerascens, Locusta migratoria migratorioides, and their mutant albinos (Orthoptera)].
A first canonical variate analysis (factor analysis) of two geographic strains of L. m. shows that the same axes distinguish crowded from isolated animals as well as their geographical origins. Two other analyses between normal and albino strains of both localities show no differences for one strain; however for the other strain, the pigmentary mutation coincides with a solitary tendency.
[Long term prognosis after circulatory arrest].
24 PATIENTS HAVING SURVIVED MORE THAN 18 MONTHS AFTER AN EPISODE OF CIRCULATORY ARREST WERE EXAMINED WITH THE AIM OF ASSESSING THE PSYCHOLOGICAL REACTIONS TO SUCH AN INCIDENT. The results obtained were encouraging, since immediately after the circulatory arrest there were only monor troubles reflecting the simple bringing into action of defence mechanisms. Long term adaptation was deemed excellent in 80 p.cent of cases which should, nevertheless, lead to any underestimation of those sequelae which, though happily rare, are highly incapacitating.
[Supernumerary chromosomes and the inclination toward the solitary phenotype of the migratory cricket Locusta migratoria mogratorioides R and F. Pigment changes under the effect of carbon dioxide].
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[The ARO dental articulator].
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[Problems raised by general surgical operation in patients with heart disease].
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[Congenital systemic arteriovenous fistula: an unusual cause of continuous thoracic murmur].
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