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Biomedical subjects

F Laurent

Publications and source records attributed to F Laurent.

At least 217 records · Page 12Linked to original sources
PubMed1978

Effect of free fatty acids and amino acids on glucagon and insulin secretions in normal and diabetic ducks.

The relationship between two metabolites free fatty acids (FFA) and amino acids (AA), and the two main pancreatic hormones, insulin and glucagon, was studied by infusing small amounts of these metabolites into normal and diabetic Peking ducks, i.e. two days after subtotal pancreatectomy. Infusion of oleic acid (0.365 g/kg/30 min as an emulsion in plasma) indicated a suppressive effect of free fatty acids on glucagon secretion, but was without effect on insulin secretion, in normal as well as in diabetic ducks, indicating that insulin might not be directly involved in the FFA-glucagon feedback in the duck. Infusions of arginine for one hour (1 g/kg/h) into normal ducks, hyperglycaemic normal birds (as a result of glucose infusion: 1 g/kg/h) and diabetic ducks, suggested the persistence of amino acid effect on glucagon secretion, and a slight reduction of the effect on insulin secretion in diabetes. This suggests that insulin may not be involved in amino acid-induced glucagon secretion in the duck.

Animals↗
PubMed1978

[Pathological data of 92 rheumatic mitral valve after surgical ablation : comparison with pre-operative echocardiography results].

The echocardiographic information obtained pre-operatively with an electronic linear scanning system (Multiscan) was compared with the results of pathological examination of the excised mitral valve in 92 patients, and showed a close correlation. The way in which the pathological changes influence the various parameters usually used to distinguish this type of rheumatic valvular disease is demonstrated. Two-dimensional imagery provides precise information : this is shown by comparison of the still frames of the videoscopic recording and the photographs of the corresponding pathological specimens. Valve thickness, length and thickness of the chordae, calcification, mitral valve surface and commissural separation are well shown, especially at the anterior leaflet. Study of transverse incidences seems the most reliable method of estimating mitral valve area. Systolic separation of mitral valve echos, according to the usual criteria, is a good sign of associated mitral incompetence and was found in 83% of cases of mixed mitral valve disease. The mean values of anterior mitral leaflet excursion, diastolic slope and opening speeds were compared in three groups of mitral stanosis with preferential antatomical features and a control group of pure mitral stenosis with supple valves. No individual parameter was found to be specific for a particular antatomical feature, showing multiple correlations to be indispensable. The difficulty of diagnosis by isolated traditional echocardiography is confirmed and the association of two dimensional imagery would seem essential not only in making the diagnosis but also in the pre operative work up.

Adolescent↗
PubMed1978

[Resections of the left ventricle in the surgical treatment of parietal sequelae of myocardial infarct].

Resection of left ventricular tissue seems to be playing an increasing part in the treatment of the sequelae of myocardial infarction. In a total of 700 patients who underwent surgery for some aspect of coronary atherosclerosis, 40 underwent resection of left ventricular tissue. In the majority of cases, diagnosis rested on left ventricular cine-angiography and in 3 cases this had to be carried out as an urgent procedure with circulatory assistance using diastolic counter-pressure (DCP) from an intra-aortic balloon. A selective contrast technique for the two coronary arteries was used whenever possible. The surgical anatomy of the lesions indicates a difference between a localised dyskinesia and diffuse dyskinesia, the latter having a severe effect on left ventricular function. In a group of localised dyskinesias, the territory supplied by the anterior descending artery was by far the most frequently affected. Resection of left ventricular tissue was associated with a myocardial bypass revascularisation procedure in 9 cases, valve repair in 7 cases, and closure of a septal perforation in 3 cases. The total inpatient mortality rate is still quite high (23.1%) because of the severity and widespread nature of the coronary disease. However, the mid-and long-term results are good, the criteria being functional improvement and the actuarial 4-year survival rate.

Adult↗
PubMed1977

[Mitral replacement using a ball-valve prosthesis under hypothermic protection of the myocardium. 230 cases].

A series of 230 mitral valve replacements using exclusively the Starr-Edwards ball valve prosthesis is presented. These 230 patients underwent surgery over a 4 year period, a uniform operative technique being used. Its essential feature was the use of a standardised technique for protection of the myocardium based upon continous clamping of the aorta and deep hypothermia at around 15 degrees. The technique of myocardial hypothermia, already reported, is briefly reviewed. The results are analysed, in the short and long term. Overall hospital mortality was 6.9 per cent, including multiple valve replacements and combined coronary surgery. The total number of thrombo-embolic complications was 8, including 1 early thrombosis out of 230 patients - i.e. 0.4 per cent and 7 late thrombo-embolic episodes out of 180 patients followed up for 1 month to 4 years - i.e. 3.8 per cent. Secondary and late mortality was 11 cases out of 180 patients. The survival rate at 4 years was 78 per cent by actuarial calculation, including operative mortality. These results justify the continued use of ball prosthesis, the long term thrombo-embolic risks of which are equal to or less than those of disc prosthesis, and the resistance of which to wear and tear is shown by the long postoperative survivals.

Adult↗
PubMed1977

[Proteins and blood volume after cardiac surgery under ECC and hemodilution].

The variations in protein, bodyweight and circulating blood volume during operation are studied in 18 patients operated under ECC. The frequency of hypovolemia with hypoproteinemia and over hydration of the interstitial medium is confirmed. The prolongation of ECC beyond 120 minutes is accompanied by a considerable reduction in the plasma sector. The frequency of hypovolemia must render the use of diuretics prudent. The existence of hypoproteinemia and interstitial overload suggests the value of albumin perfusions.

Blood↗
PubMed1976

Insulin and the glucose-glucagon feedback mechanism in the duck.

The relationship between insulin and the glucose-glucagon feedback mechanism was studied by testing the effectiveness of various routes, doses and timing of insulin administration prior to and during a glucose tolerance test in Peking ducks made transiently diabetic by subtotal pancreatectomy. Insulin injections or infusions given either before, or only during the glucose load, did not restore the A-cell response to glucose. Yet, if given both before and during the glucose test, in conditions which mimic the physiological basal insulin level and its variations (with, initially, intramuscular injections of 0.2 IU/kg and 8 mug/kg glucagon, every six hours, and then an intravenous injection of 3.6 mU/kg plus an infusion of 0.9 mU/kg/minute for one hour), the normal glucagon response to glucose was re-established. Insulin must therefore be present, both before and during glucose stimulation, for glucose to be effective as an A-cell suppressor.

Animals↗
PubMed1976

[Protection of the myocardium by hypothermia during extracorporeal circulation. Experimental and clinical study].

Hypothermic protection of myocardia during E.C.C. has been estimated on a 35 dogs experimental series and on a clinical series of 700 acquired cardiopathies of adult, including 400 valvular replacements and 300 aorto-coronary by-pass. Experimental results have been estimated by biochemic and morphologic controls done on myocardic samples took up by drillbiopsy. The biochemical study includes among others a dosing of the high-energy phosphorus compounds (P.C. and A.T.P.). Morphological study was done by optic and electronic microscopy. Results made clear the superiority of the hypothermic ischemia at 10 degrees C on the continued perfusion at 32 degrees C with fibrillative heart. An hypothermic protection method with successively cold perfusion of the coronary system and a heart immersion in a salted solution at 4 degrees C has been utilized during valvular and coronary surgery on human in 700 cases. The total mortality was of 5,8 p. 100. The rate of post-operative infarcts was 2,4 p. 100. Incidence of intra-ventricular conduction troubles has been 1,1 p. 100. There was no relation between mortality and morbidity of myocardic origin and the lasting of the ischemic clamp, which were of 21 mn up to 165 mn. The low incidence of complications of myocardic origin is due to the hypothermic protection of the myocardia.

Cardiac Surgical Procedures↗
PubMed1976

[Postoperative myocardial infarct after aorto-coronary bypass].

The incidence (4.3%) of myocardial infarction after aorto-coronary bypass vein graft procedures, and the mechanisms by which they occur, have been analysed in a series of 300 postoperative patients. Very careful case selection for surgery, extreme care in preserving the myocardium throughout the operation, and especially while the coronary anastomoses are being carried out, and attention to detail as they are done all contribute in varying degrees to the prevention of this complication. The particular clinical features and the natural history of this condition of post-operative infarction are recalled.

Coronary Artery Bypass↗
PubMed1975

[Factors influencing the results of aortocoronary bypass in a homogeneous series of 125 surgical patients].

A group of 125 patients having undergone aortocoronary bypass by saphenous graft was studied from the point of view of short and medium term results. The following emerged as factors likely to influence these results: --the technique used in the anastamoses and the quality of peroperative myocardial protection; --the presence of hyperlipidaemia; --the restrictive choice of indications in relation to the results of coronary arteriography; --the presence of cardiac insufficiency or an associated valvular lesion. Overall operative mortality was 8 p. cent. Routine ECG's and enzyme studies were carried out to detect postoperative myocardial necrosis. 4 postoperative infarctions without clinical symptoms or signs were detected (2.4 p. cent). 26 patients underwent surgery as an emergency with simultaneous coronary arteriography and surgery in 24. The mortality in this group was not greater (7.6 p. cent) than in the group as a whole. By contrast, mortality was greater in the presence of cardiac insufficiency (25 p. cent) or an associated valvular lesion (16.5 p. cent).

Adult↗