[Measurement of cardiac output by CO2 rebreathing technique. A study of reproducibility in the normal subject; application to cardiac insufficiency]. / Mesure du débit cardiaque par technique du CO2 rebreathing. Etude de reproductibilité chez le sujet sain, application à l'insuffisance cardiaque.

A feasibility and reproducibility study of cardiac output measurement by CO2 rebreathing was performed in normal subjects and in patients with compensated cardiac failure. The measurements were performed at rest and at the second stage of the Bruce protocol in normal subjects (N = 12) with a good reproducibility (r = 0.81) after an interval of two days. In patients with stable cardiac failure (N = 17), the cardiac outputs were 9.4 +/- 3.9 l/min and 9.3 +/- 3.1 l/min by measuring the arterial pCO2 and end-expiratory CO2 compared with the theoretical value of 9.9 +/- 2 l/min. The non-invasive measurement of cardiac output by the CO2 rebreathing method was well tolerated by patients and is reliable and reproducible.

[Return to work after myocardial infarction: evaluation and decision]. / La reprise du travail après infarctus du myocarde: bilan et décisions.

Working capacity after myocardial infarction depends on the physical and cardiovascular status, psychological repercussions and conditions of work. The latter two are much more important than the first two factors. Cardiovascular functional status is readily assessed by the large number of available investigations which leave little unknown. Exercise stress testing during the second week is the most cost-efficient investigation, providing reliable and sufficiently quantifiable data about the possible sequellae of cardiac failure on effort, ischemia and arrhythmias: an idea of the patient's functional capacity and circulatory responses (athletic, hyperkinetic) may also be obtained allowing adjustment of treatment to improve exercise capacity which goes much further than the statistical hope of prolonging survival. However, it would be naive to think that a satisfactory exercise stress test guarantees the patients' capacity to return to work. Psychological and sociological factors are more important by far. The dominant trait of the post-infarction psychological syndrome must be identified (anxiety, depression, negation): the positive and negative influences of the family, social and professional environment must be evaluated. A good knowledge of the patient's working conditions is essential to go against a number of taboos hindering the return to work (stress, stairs, restaurant meals, etc...). Finally, the medico-legal relationship between the infarct and work should not be neglected: the management of myocardial infarction when an occupational disease must respect the legislative and judicial texts which do not always correspond with everyday clinical practice. There is a lack of structures for cardiac function testing for assessing physical aptitude: we suggest that in the context of the proposed hospital reforms, departmental heads should consider setting up such units which would have a specific task respecting the spirit of these reforms. Nevertheless, cardiologists should pay more attention to the convalescent phase of infarction. This is the time when many social catastrophes can be avoided.

Histamine as a ligand in blood plasma. Part 7. Malate, malonate, maleate and tartrate as adjuvants of zinc to favour histamine tissue diffusion through mixed-ligand coordination. In vitro tests on lymphocyte proliferation.

Investigations based on computer simulated distributions of histamine in blood plasma were recently devoted to the assessment of the roles of cysteine, aspartic and glutamic acids as possible adjuvants of zinc to favour histamine tissue diffusion through mixed-ligand coordination. Since all tissues contain at least one of the two enzymes required for the catabolism of histamine, any increase of its tissue diffusion is expected to result in an acceleration of its degradation, which may be of interest for the treatment of anaphylactic disorders. As an extension of these studies, the present paper first reports (i) an experimental investigation of the tendency of four dicarboxylic acids, namely malate, malonate, tartrate and maleate, to mixed-ligand coordination with zinc and histamine, (ii) computer-based potential effects to be expected from the association of these agents to zinc with respect to histamine tissue diffusion. Cell culture studies were then used to test simulation expectations. Two series of experiments involving successively human lymphocytes and a lymphoblastoid cell line (8866) have been carried out, which led to the following conclusions: (i) the hypothesis formerly put forward that cysteine could favour histamine tissue diffusion through mixed-ligand coordination with zinc has been validated on the two cell models, (ii) the formerly established suppressive role of histamine versus lymphocyte proliferation has clearly been confirmed, (iii) moreover, this suppressive effect has been shown to occur correlatively to histamine uptake by these cells, (iv) the four dicarboxylic acids, more especially tartric acid, proved effective as catalysts of the two above processes. Possible biomedical applications of these results are discussed.