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Biomedical subjects

P Y Hatt

Publications and source records attributed to P Y Hatt.

At least 19 recordsLinked to original sources
PubMed1979

[Detection of pulmonary embolisms by recording of the variations of thoracic impedance at each lung].

It is possible to record changes of volume caused by variations of the blood supply to each lung by measuring the transthoracic electrical impedance. A theoretical study was performed beforehand to define the variations of the impedance of the deep-lying structures. The form, number and distribution of the electrodes were determined by experiments on a model so that only variations of the impedance of the pulmonary parenchyma, and not of the mediastinum, were recorded. In this way the origins of the signals recorded were known. The validity of the method was tested on patients having undergone pneumonectomy and on patients with defects of pulmonary perfusion. Using the data obtained during the preceding experimental studies it was possible to defect perfusion defects caused by pulmonary embolism. Five cases of pulmonary embolism, confirmed by angiography and lung scan, of varying severity and chronicity, are reported. The amplitude of the impedance curve was reduced on the affected side, the difference of amplitude between the two being related to the degree of vascular amputation.

Adult↗
PubMed1979

[Contribution of ultrastructural analysis to the knowledge of the neuromuscular relationships in the nodal and conduction tissue].

The ultrastructure of the atrio-ventricular junction in the rat heart fixed in situ was studied on serial fine sections. The relationships between the specialized tissue and the nervous system were studied after labelling adrenergic endings with 5-OH-dopamine. Among the various types of nerve endings a distinction may be made between: 1) adrenergic or cholinergic free endings; 2) large "cluster" endings of the cholinergic types, seen mainly in the equatorial regions of nodal cells; 3) small diameter cholinergic before the development of heart failure or significant card synaptic images; 4) afferent neurons, whose endings, rich in glycogen and mitochondria supply the conduction tissue fibres, getting into or through the muscle fibre. The intermembrane space is then 20 nm. The analogy between the images observed and the ultrastructural aspects of intrafusorial fibres in skeletal muscle is discussed.

Adrenergic Fibers↗
PubMed1979

[The left ventricle at different stages of a two steps mechanical overloading. Electron microscopic study in the rat (author's transl)].

The left ventricle myocardium of rats subjected to a two steps mechanical overloading (abdominal aorta constriction + aortic insufficiency) was examined in the light and electron microscopes at several stages of the load, and particularly after 3 to 6 months when the animals exhibited congestive heart failure. In these conditions, the heart weight exceeded the control by more than 100 %. In the later stages, the absence of parallelism between heart weight and cell diameter was compatible with a process of hyperplasia. Cellular lesions looking like recent were found more and more frequently with time. Within apparently normal cells proliferation of small mitochondria, nucleoli and Golgi apparatus are compatible with some deficit in energy balance, which is usually encountered only in early stages of the load.

Animals↗
PubMed1979

[Endomyocardial biopsy results and left ventricular function in primary myocardiopathies (author's transl)].

Endomyocardial biopsies (EMB) of the left ventricle (LV) were performed during cardiac catheterization in 27 patients with apparently primary myocardiopathies (PMC). The results of optical and electron microscopy were compared with ventricular performance indices calculated from hemodynamic and cinematographic data from the left ventricle. The telediastolic pressure of the LV increases with the spread of fibrosis (r = 0.68) suggesting that it disturbs the filling of this cavity. Systolic effort is reduced as this fibrosis increases (r = 0.56), and it contributes to the changes in the pumping function of the LV, but the contractile power of the LV is altered in a less evident and less constant manner. The association of cell and fibro-elastic tissue degeneration is always accompanied by a drop in ventricular performance (p less than 0.0001). Apart from its diagnostic role, which is limited but may be of great value, the EMB can help to clarify the physiopathology of PMC and to formulate a prognosis based on more solid grounds.

Biopsy↗
PubMed1978

[Biochemistry of myocardium taken at autopsy. Preliminary report].

The findings after biochemical analysis of heart muscle taken at autopsy are given in this preliminary communication. Human myosin is made up of two heavy sub-units and two light sub-units: it is similar to cardiac myosin found in other mammals, but is different in certain characteristics, particularly immunological ones. Tropomyosin is made up of two different sub-units. The normal human heart contains 1 mg of collagen and 130 microgram of desoxyribonucleic acid (DNA) per 100 mg of fresh tissue. The degree of cardiac hypertrophy correlates with the increase total DNA within the heart, and with the lowering of myofibrillary Ca2+ ATPase, the concentration in the collagen remaining unchanged providing there is no ischaemic heart disease. These techniques may be used to quantify several factors, such as the degree of sclerosis or the nuclear mass in ill-understood conditions such as the primary cardiomyopathies.

Actins↗
PubMed1976

[Anomalous ventricular contractile performance in experimental chronic aortic insufficiency in the dog].

Hemodynamics and right (RV) and left (LV) ventricular performances of anaesthetized, closed-chest animals were studied in normal control dogs (N) and in dogs with aortic insufficiency (AI), the latter intervention being performed 33 months before verification. In dogs with AI, LV was hypertrophied (N = 49.6 +/- 6.3 g; AI = 98.7 +/- 10.1, p less than 0.001); forward stroke volume was slightly decreased (N = 20.0 +/- 2.2 ml; IA = 14.6 +/- 5.4 ml, p = NS);LV and diastolic pressure was increased (N = 9.4 +/- 1.4 mmHg; IA = 16.7 +/- 2.9, p less than 0.05); both RV and LV myocardial performace index (e.g. dP/dt max, peak VCE, Vmax) were normals. Relative pressure/velocity of shortening and wall stress/velocity of shortening relationships, however, were decreased, when measured during L.V. isovolumetric beats. LV stiffness of arrested heart was increased in proportions with hypertrophy extent. Thus, myocardial performance of chronically volume-overloaded heart appears to be depressed before the stage of the circulatory failure.

Animals↗
PubMed1976

[Degree of granularity of the atrial cardiocytes. Morphometric study in rats subjected to different types of water and sodium load (author's transl)].

Morphometric analysis was applied to the evaluation of the atrial cardiocytes specific granules, in rats subjected to different types of water and sodium load. In control animals, the right atrium is more granulated than the left one and the interauricular septum. Ipsilateral atrium and auricle have the same index of granularity. Five types of water and sodium load were tested - I. Full water restriction - II. Sodium restriction with normal water intake - III. Controls - IV. Sodium overloading - V. Sodium and Doca overloading. From groups I to V, the index of granularity decreases progressively. The same phenomenon does not appear in the left atrium, except for the group II (sodium restriction) whose index is higher (p less than 0.001) than in the other groups. These data are not incompatible with the existence of a relationship between the presence of atrial specific granules and the atrial volosensitivity. An analogy between these cells and the myopithelioid cells of the juxtaglomerular apparatus is then suggested.

Animals↗
PubMed1976

[Blood digoxin and treatment of heart failure in aged patients].

Serum digoxin level was determined by radioimmunoassay in 76 elderly in-patients (age: 76.1 +/- 1.0) which were treated by digoxin without any evidence of toxicity. Digoxin levels was related to blood nitrogen (p less than 0,01); on the other hand, no relationship between others factors influencing the digoxin bioavailability (age, body weight, associated drug) and digoxin levels could be found. Therapeutic effectiveness, as estimated by ventricular rate and signs and symptoms, was not dependent of digoxin levels. In patients with higher functional class (III and IV NYHA), however, digoxin level was generally demonstrated to be increased. Digoxin levels were lower in patients with coronary heart disease (1.71 +/- 0,22 ng/ml; n = 16) than in patients with right ventricle overload (2.94 +/- 0,74 mg/ml; n + 7 - p less than 0.05). Because of the very large scattering of digoxin levels, digoxin determination seems to be useful in measuring individual bioavailability and therapeutic effectiveness, and leading to the best base line of any individual treatment.

Age Factors↗
PubMed1975

Rat myocardial mechanics during pressure-induced hypertrophy development and reversal.

Moderate cardiac hypertrophy (CH) was produced in rats by abdominal aorta constriction for 5, 8, 15, 21, and 28 days. Aortic constriction release after 5, 8, and 15 days led to CH regression, which was complete within 15 days. A study of left ventricular papillary muscle mechanics during CH development demonstrated an early but transitory decrease in both maximum isometric force (Po) and maximum muscle shortening velocity (max V); in addition, the time-to-peak tension increased, and there was a decrease in isometric relaxation rate and in force-frequency relationship (negative staircase.) After CH regression, isometric relaxation and negative staircase were similar to controls, whereas the prolonged duration of contraction persisted. After release of the aortic constriction at 8 and 15 days, Po and max V were normal; however, after the earlier release (5 days), Po was higher than control, when muscle thickness was taken into consideration. These findings suggest 1) that an alteration in muscle mechanics may be related to the hypertrophy itself; 2) that anomalous excitation-contraction coupling might persist after CH regression.

Animals↗
PubMed1975

A comparative study of the activity of a new agent, indapamide, in essential arterial hypertension.

A single-blind crossover trial was carried out in 38 elderly, hospitalised patients with essential hypertension to compare the hypotensive activity of 5 mg. indapamide daily with 100 mg. chlorthalidone daily. After initial treatment for 10 days with placebo, patients received treatment for 45 days with either indapamide or chlorthalidone and were then crossed over to the alternative drug for a similar period. Potassium supplementation was necessary in 25 of the patients receiving chlorthalidone, but was precribed as a precautionary measure in only 1 patients whilst on indapamide. Results showed that there were significant drops in blood pressure following both active medications, but that the percentage reduction in diastolic pressure was greater after indapamide. Indapamide also proved more effective than chlorthalidone in controlling the patients' subjective and functional symptoms of their hypertension. In an overall assessment of the effectiveness of both drugs, indapamide was judged to be better tolerated as well as more effective than chlorthalidone in 18 of the 38 patients, whilst chlorthalidone was preferred in only 7 instances.

Aged↗