Biomedical subjects
Publications and source records attributed to P Fritsch.
The in vitro transformation of nitrates in nitrites in the various parts of the gastro-intestinal tract has been analysed in the Rat. Results show that nitrites can be found at the different levels of the alimentary tract, especially in the stomach and small intestine. This nitrite production is discussed with regard to the possible formation of nitrosamines in mammals.
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The association of different experimental methods using radioactive particulate aerosols with bronchial washing and morphometric techniques reveals the importance of alveolar macrophages in antibacterial defense and the interest of their quantitative evaluation. The study of the kinetics of pulmonary phagocytic systems has shown a "capillary compartment", which consists of a reserve of monocytes which are temporarily present in the lung and in transit through it. This reserve represents 4.6% (sigma=1.4) of the cells from deep in the lung and is much larger than the systemic monocytic pool. 0.5% of these monocytes are in a phase of DNA synthesis. This capillary compartment must be clearly separated from interstitial phagocytes, the number of which is insignificant under physiological conditions. The phagocytic relay by polynuclear elements appears during bacterial aggression and is interdependent with macrophagic population. The particularities of the immune defenses of the distal parts of the lung are stressed especially in comparison with systemic defenses.
We have studied, in rats, the influence of the intratracheal injection of 30 X 10(6) Staphylococcus aureus upon the differential count and renewal of the cell populations extracted by pulmonary lavage. In vivo labelling of alveolar macrophages was performed by intratracheal injection of 125I iododeoxyuridine, and the evolution of the labelled population was quantitatively followed up after scheduled sacrifice. Dividing cells were also identified at all times in the lavage population, after incorporation of (3H)-thymidine in vitro and autoradiography. The injection of Staphylococcus aureus induced an acute inflammatory process followed by the migration of polymorphonuclears, lymphocytes and macrophages mainly during the first 24 hours. Later on, no viable bacteria were observed and the cell populations returned to control values. Kinetic parameters were found varying as a function of the cell type. The early increase of macrophages was mainly produced by the migration of monocytes, which exhibited a shorter lifespan in alveolus than did resident macrophages. The inflammatory reaction observed, whilst inducing a considerable modification of the cell distributions, did not significantly modify the lifespan of macrophages located within alveolus before the aggression.