Biomedical subjects
Publications and source records attributed to M Marchand.
The authors report the case of a systemic embolism of a cusp of a Hancock pericardial aortic bioprosthesis. This rare complication has not been previously reported to the authors' knowledge, and should lead to immediate valve replacement.
With the improvement in the results of cardiac transplantation, more and more cardiologists are called on to follow up cardiac transplant patients. Cardiological follow-up requires a knowledge of the electrocardiographic and electrophysiological features of the transplanted heart after surgery and the suppression of autonomic innervation. The transplanted heart ECG is characterised by the presence of 2 P waves of different morphology and frequency (from the native and transplanted atria), an acceleration of the sinus rhythm, clockwise rotation of the longitudinal axis, right bundle branch block and ST-T segment changes. The increase in heart rate during exercise is catecholamine-dependent, more progressive and less important than in normal subjects, as is the deceleration of the cardiac rhythm when exercise is stopped. The observation of early sinus node dysfunction is not rare (6.6%) and though usually asymptomatic and transient, implantation of a pacemaker is commonly proposed with different modes of stimulation (VVI, VVIR, AAIR, AAT). The authors have observed changes in the electrophysiological properties of experimental transplanted hearts during acute rejection. The most important of these were in the conduction of the activation within the atrium and in the atrioventricular node, and a reduction in the amplitude of the ventricular potential. The recording of these changes in humans by a non-invasive method could help early diagnosis of acute rejection and limit the number of endomyocardial biopsies. Of the non-invasive techniques under assessment, signal-averaged electrocardiography (temporal and/or frequency analysis) seems to be the most promising.
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In assessing the effectiveness of lower-limb and upper-limb nonspecific physical training, we have considered 3 objectives in this study: (1) determination of clinical and functional actual state in patients with chronic airway obstruction (CAO), before and after training; (2) determination of the tests, level of work, and duration of the session training as well as how to increase the training load throughout the training program; and (3) the "particular" upper-limb exercise training in patients with CAO. Many personal factors such as psychologic (personality, degree of patient motivation), alcohol and smoking habits, physical activity, malnutrition, as well as routine tests, at rest and maximal exercise, including the control of metabolic acidosis (lactate) and arterial blood gases (or at least of SaO2), should be considered. Exercise training has the potential to improve exercise tolerance in those who develop metabolic acidosis. The pattern of lactates during exercise represents a good criterion on the selection of patient's training. Two ergospirometric strategies, at high intensity exercise, established from the anaerobic threshold (AT) are described: (a) the above AT 45 min constant exercise (high work rate), at 60% of the difference between AT and maximum VO2 or 80% of the maximal tolerated power (MTP), and (b) the "45 min square-wave endurance exercise test" (SWEET), simulating an interval training session, established from the MTP and the AT. To the SWEET's base (% MTP from AT or aerobic training), a peak of 60 s at MTP (anaerobic training) is added every 5 min. While those 2 protocols, after 6 to 8 weeks of training, lactate and ventilation were lower for identical work rate. In addition, endurance (time in "a" and total physical work in "b") increased up to 60%. Further, maximal exercise ventilation and maximum VO2 increased after SWEET training. Roughly every 7 training sessions, a 10% to 15% reduction in heart rate (HR), during the training program, allows the patient to increase the work rate of the sessions. Evaluation of training the upper limb in patients with CAO requires measurements of MTP and maximum VO2. With the upper limb (wheelchair ergometer), Wmax, maximum VO2, and HR represent 30%, 65%, and 95%, respectively, of the lower limb (ergometer). Further, some expiratory and inspiratory accessory muscles show electromyographic fatigue at the MTP upper-limb level. This may contribute to the rationale for training respiratory muscles.(ABSTRACT TRUNCATED AT 400 WORDS)
Trypanosoma brucei contains two isoenzymes for glyceraldehyde-3-phosphate dehydrogenase: one enzyme resides in a microbody-like organelle, the glycosome; the other is found in the cytosol. Previously we have reported the characterization of the gene for the glycosomal enzyme [Michels, P. A. M., Poliszczak, A., Osinga, K. A., Misset, O., Van Beeumen, J., Wierenga, R. K., Borst, P. & Opperdoes, F. R. (1986) EMBO J. 5, 1049-1056]. Here we describe the cloning and analysis of the gene that codes for the cytosolic isoenzyme. The gene encodes a polypeptide of 330 amino acids, with a calculated molecular mass of 35440 Da. The two isoenzymes are only 55% identical. The cytosolic glyceraldehyde-3-phosphate dehydrogenase differs from the glycosomal enzyme in the following respects: (a) its subunit molecular mass is 3.4 kDa smaller due to the absence of insertions and a small C-terminal extension which are unique to the glycosomal protein; (b) the cytosolic enzyme has a lower pI (7.9, as compared to 9.3 for the glycosomal isoenzyme), which is due to a reduction in the excess of positively charged amino acids (the calculated net charges of the polypeptides are +2 and +11, respectively). We have compared the amino acid sequences of the two T. brucei glyceraldehyde-3-phosphate dehydrogenases, with 24 available sequences of the corresponding enzyme of other organisms from various phylogenetic groups. On the basis of this comparison an evolutionary tree was constructed. This analysis strongly supports the theory that T. brucei diverged early in evolution from the main eukaryotic branch of the phylogenetic tree. Further, two separate branches for the lineages leading to Trypanosoma are inferred from the amino acid sequences, suggesting that the genes for the two glyceraldehyde-3-phosphate dehydrogenases of the trypanosome are distantly related and must have been acquired independently by the trypanosomal ancestor. The branching determined with the glycosomal enzyme precedes that found with the cytosolic enzyme. The available data do not allow us to decide which of the two genes originally belonged to the trypanosome lineage and which entered the cell later by horizontal gene transfer.
Intraoperative Doppler sonographic examinations were carried out on seven preterm neonates to measure cerebral blood flow velocity changes in the anterior cerebral arteries during ductus arteriosus ligation. Age at surgery was 12 +/- 6 days. Continuous recordings during the operative procedure showed a rapid increase in diastolic blood pressure (P less than 0.01), whereas systolic blood pressure was not significantly higher compared with pre-occlusion values. In the anterior cerebral arteries, ductal closure led to a decrease in resistance index of Pourcelot (mean = 1.02 +/- 0.08 vs 0.65 +/- 0.07 (P less than 0.001)) and to an increase in area under the velocity curve (mean = 3.64 +/- 0.38 vs 8.16 +/- 1.07 (P less than 0.001)). These changes were associated with a corresponding increase of the end diastolic flow velocity (P less than 0.001) but no change in the peak systolic velocity. The heart rate did not change significantly during ductal closure. TcPO2, TcPCO2 remained normal during the study period. These data indicate that changes in cerebral blood flow velocity during surgical ligation are principally determined by changes in systemic diastolic pressure. Systolic blood pressure and peak systolic flow velocity remain unchanged or slightly higher than preligation values, thereby restoring normal cerebral blood flow velocity pattern without increasing the stress on the wall of cerebral vessels and thus the risk of peri-intraventricular haemorrhage.
"In this paper, we examine the optimal pay-as-you-go social security scheme which reallocates resources across generations in a changing environment, that is, with fluctuations in population growth rates and in productivity levels. We use an overlapping generations model along with a social welfare function consisting of the sum of generational utilities either unweighted or weighted by population size and a discount factor. We show how intergenerational resource sharing can be used to improve social welfare even though the extent of intergenerational redistribution is hampered by payroll tax deadweight losses...." The authors also consider the effects of an economy's openness on resource sharing. The geographical focus is on developed countries.
A group of 11 strains, mostly isolated from sewage water in the Province of Navarra, Spain, were found to constitute a DNA relatedness group which is 2 to 39% related to 23 species of the genus Vibrio and 2 to 3% related to two Aeromonas species. Phenotypically, these strains have all of the properties that define the genus Vibrio. However, they differ from the previously described species by three or more properties. The strains are negative for arginine, ornithine, and lysine decarboxylase activities and the Voges-Proskauer test and are unable to utilize putrescine, gluconate, glucuronate, and histidine. They utilize and produce acid from sucrose and grow at 40 degrees C. All strains grow in the presence of 0.5% (wt/vol) NaCl, and seven strains grow weakly in peptone water lacking NaCl. The group of strains which we studied can also be differentiated from other Vibrio species by fatty acid content. The G+C ratio of the DNA is 45 to 47 mol%. The name Vibrio navarrensis sp. nov. is proposed for these strains; strain 1397-6 (= CIP 103381) is the type strain.
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The cellular fatty acid compositions of 51 Vibrio strains belonging to 22 species as well as five Aeromonas strains were determined by using capillary gas-liquid chromatography (GLC). The major fatty acids were most often hexadecenoic, hexadecanoic and octadecenoic acids. Heptadecenoic acid was present in significant amounts in V. alginolyticus, V. natriegens, V. parahaemolyticus and "Vibrio navarrensis". Twenty fatty acids including branched and hydroxy acids were detected in the genus Vibrio. Quantitative results were treated by principal component analysis to display groups of strains. The first three components (accounting for 69% of the variance) showed the type strains of V. fischeri, V. ordalii, V. damsela, V. mediterranei, V. tubiashii, V. campbellii, V. pelagius, V. gazogenes, and V. nereis to be unclustered. V. alginolyticus (4 strains) and V. parahaemolyticus (4 strains) showed some overlap and the type strain of V. natriegens was in their neighborhood. V. harveyi (4 strains) formed a cluster and V. vulnificus was in its vicinity. V. cholerae (5 strains) overlapped with V. diazotrophicus (3 strains) and was close to the type strain of V. mimicus and V. anguillarum. V. metschnikovii (3 strains) clustered with the type strain of V. cincinnatiensis. A decision tree was devised for the identification of Vibrio species based on qualitative characteristics of fatty acid patterns. However, the following three groups, V. alginolyticus-V. parahaemolyticus-V. natriegens, V. metschnikovii-V. cincinnatiensis and V. cholerae-V. mimicus could not be split into such a decision tree.
Study of the interface between blood and artificial surfaces reveals numerous undesirable reactions. For example, the formation of biologically active peptides, C3a and C5a (anaphylatoxins), is a result of complement activation via the alternative pathway. It cannot be denied that the reinjection of large quantities of these molecules could be at the origin of serious side effects. We report herein the anaphylatoxin levels found with 9 hemapheresis procedures (4 plasma filtration membranes, 3 systems for platelet collection, 2 plasma treatment techniques (dextran sulfate cellulose column and cascade filtration)). All the filtration procedures generated very high levels of anaphylatoxins, especially C3a. In contrast, the centrifugation systems produced lower levels. However, considerable amounts of C3a were found with the Cobe Spectra and V50 Haemonetics blood cell separators. The anaphylatoxins generated by the primary filter were partially retained by the dextran sulfate column. These high toxin levels enable an assessment of the degree of hemo-incompatibility of these systems. However, it remains difficult to evaluate whether these anaphylatoxins are dangerous or not.
In Trypanosoma brucei the enzyme glucose-6-phosphate isomerase, like most other enzymes of the glycolytic pathway, resides in a microbody-like organelle, the glycosome. Here we report a detailed study of this enzyme, involving a determination of its kinetic properties and the cloning and sequence analysis of its gene. The gene codes for a polypeptide of 606 amino acids, with a calculated Mr of 67280. The protein predicted from the gene sequence has 54-58% positional identity with its yeast and mammalian counterparts. Compared to those other glucose-6-phosphate isomerases the trypanosomal enzyme contains an additional 38-49 amino acids in its N-terminal domain, as well as a number of small insertions and deletions. The additional amino acids are responsible for the 5-kDa-larger subunit mass of the T. brucei enzyme, as measured by gel electrophoresis. The glucose-6-phosphate isomerase of the trypanosome has no excess of positive residues and, consequently, no high isoelectric point, in contrast to the other glycolytic enzymes that are present in the glycosome. However, similar to other glycosomal proteins analyzed so far, specific clusters of positive residues can be recognized in the primary structure. Comparison of the kinetic properties of the T. brucei glucose-6-phosphate isomerase with those of the yeast and rabbit muscle enzymes did not reveal major differences. The three enzymes have very similar pH profiles. The affinity for the substrate fructose 6-phosphate (Km = 0.122 mM) and the inhibition constant for the competitive inhibitor gluconate 6-phosphate (Ki = 0.14 mM) are in the same range as those of the similar enzymes. The Km shows the same strong dependence on salt as the rabbit muscle enzyme, although somewhat less than the yeast glucose-6-phosphate isomerase. The trypanocidal drug suramin inhibits the T. brucei and yeast enzymes to the same extent (Ki = 0.29 and 0.36 mM, respectively), but it had no effect on the rabbit muscle enzyme. Agaricic acid, a potent inhibitor of various glycosomal enzymes of T. brucei, has also a strong, irreversible effect on glucose-6-phosphate isomerase, while leaving the yeast and mammalian enzymes relatively unaffected.
The frequency of primary dysfunction of 432 Hancock pericardial bioprosthesis was evaluated during a mean follow-up period of 53.1 months per patient. This frequency was 3.20% valve-year in mitral valve prosthesis and 0.92% valve-year in aortic valve prosthesis. Only one case of calcification was noted. Dysfunction was usually due to tearing of one or several pericardial cusps (25 cases), occasionally to tissue retraction (4 cases). Pathological examination of the explanted valves showed fibrin formation followed by organization into fibrous tissue in the host, retracting or fragilizing the pericardial valvular tissue. A preliminary study of the same group had led to discontinuation of Hancock prosthesis. The long follow-up period makes it possible to compare the results obtained with those of pericardial prosthesis of the same generation, to stress the need for echocardiographic monitoring of the implanted valves and to hope that new techniques of pericardial valve fitting will improve the mechanical reliability of prosthesis which, from the point of view of thrombogenesis and haemodynamics, have unquestionable advantages.
Right ventricular volume and ejection fraction were measured in children who had undergone surgical repair for tetralogy of Fallot with excellent results. Fourteen children who had been operated upon at the age of 3 +/- 2.6 years had cardiac catheterization and cineangiography of the right ventricle at the age of 4.6 +/- 2.7 years. Right ventricular volumes were determined from single-plane cineangiography in right anterior oblique projection (Ferlinz method). Eleven children with a normal right ventricle served as controls. Dual projection cineangiography of the pulmonary artery enabled the pulmonary insufficiency to be divided into 4 grades. Echocardiography with colour-coded doppler velocimetry was also performed, showing the absence of residual shunt and of tricuspid, mitral and aortic valve abnormalities. The extension of pulmonary regurgitation flow to the right ventricle was analysed and divided into 4 grades. Pulmonary insufficiency was present in all patients; it was graded 1 or 2 by the two methods in 8 cases (group A) and 3 or 4 by one or the other of the two methods in 6 cases (group B). In 7 patients of group A the operation had included the insertion of a small patch to widen the pulmonary channels (infundibulum alone in 3 cases, transvalvular in 4 cases); in 5 patients of group B a large infundibulo-pulmonary transvalvular patch had been installed. The right ventricular systolic pressure was always below 50 mmHg (mean: 40.9 +/- 6.7 mmHg) and the systolic gradient between right ventricle and pulmonary artery never exceeded 30 mmHg (mean: 14.9 +/- 6.2 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)
The authors report a case of total anomalous pulmonary venous return (TAPVR) draining into the innominate (brachiocephalic) vein, discovered in a 40-year old male patient and successfully treated by surgery. This type of cardiopathy is usually suspected in the neonatal period, being badly tolerated, and such a prolonged survival is quite exceptional. Survival is conditioned by the site of the TAPVR, by the size of the atrial septal defect and also by the presence or absence of an obstacle to the pulmonary venous return and of pulmonary arterial hypertension. In the absence of pulmonary vascular disease, surgical correction is mandatory and results in regression of the symptoms and of the pulmonary arterial hypertension.
Amongst the rare causes of haemoptysis rupture of the great vessels is always a possibility. An aorto-bronchial fistula is a rare complication of thoracic aneurysms of the aorta. A fistula starting from a false aneurysm is exceptionally rare. Our observation concerns a patient of 61 with previous vascular problems who was discovered to have a mediastinal tumour following dysphonia and haemoptysis. Aortography and surgical intervention revealed that this was a false aneurysm of the horizontal part of the aorta which had developed a fistula in the bronchus.
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