PubMed Health⌕ Search

Biomedical subjects

H STAHELIN

Publications and source records attributed to H STAHELIN.

11 recordsLinked to original sources
PubMed1957

Studies on the interaction between phagocytes and tubercle bacilli. III. Some metabolic effects in guinea pigs associated with infection with tubercle bacilli.

In continuing studies concerning the interactions between phagocytes and tubercle bacilli the effect of tuberculous infection on respiration and glucose utilization was investigated in guinea pigs. Peritoneal exudates rich in polymorphonuclear leucocytes, derived from guinea pigs infected with tubercle bacilli, had a significantly higher rate of respiration than the same cells from normal animals. The difference between cells from normal and infected animals was greater when the animals were infected with a virulent strain (Vallée) than when infected with an attenuated one (R1Rv or BCG). By the use of glucose labelled with C(14) at position 1 or 6, or uniformly labelled glucose, it was established that this difference in oxygen uptake between normal and infected cells was probably not caused by a difference in the pathway of glucose utilization. Similarly, the respiration of liver and kidney slices from normal and infected guinea pigs was compared and it was found that liver slices showed differences similar to those shown by leucocytes, but that the kidney slices did not. The possibility has not been ruled out that the difference in rate of respiration of liver slices due to infection might be caused by tuberculous lesions in the livers of infected animals. The mononuclear cells which invade the liver have a higher rate of oxygen uptake than liver cells. The rate of glucose utilization and the total amount of CO(2) produced was also determined in intact guinea pigs. Both functions were found not to differ significantly in normal and infected animals. The rate of production of CO(2) from C(1) and C(6) of glucose was the same in both groups of animals. The ratio of the rate of production of C(14)O(2) from C(1) and C(6) of glucose by the whole animal was found to be about 1.35. It was found to be much higher with polymorphonuclear leucocytes (C(1)/C(6) = 8 in the absence of serum). During the process of phagocytosis this ratio increased from about 25 to about 130 (in the presence of 2 per cent serum) indicating an increase in the direct oxidative pathway of glucose utilization during stimulated cellular activity.

Animals↗
PubMed1956

Studies on the interaction between phagocytes and tubercle bacilli. I. Observations on the metabolism of guinea pig leucocytes and the influence of phagocytosis.

As a basis for studies on the interaction of phagocytes and tubercle bacilli experiments were carried out to obtain information on some biochemical characteristics of exudate leucocytes from guinea pigs. It was found that total cellular phosphorus was the most suitable measure of protoplasm. Cell counts were less reliable because of unavoidable clumping in the suspension, and dry weight measurements were less specific when contamination with erythrocytes occurred. The utility of phosphorus measurements in this connection depends upon the fact that an erythrocyte contains only 4 per cent of the phosphorus present in a leucocyte. From measurements on mixed suspensions consisting of varying known proportions of polymorphonuclear and mononuclear leucocytes as determined by differential counting, it was possible to compute true values for these two cell types with respect to oxygen consumption and lactic acid production. Thus it was found that monocytes consumed considerably more oxygen and produced more lactate than polymorphonuclear leucocytes. From the data obtained it is suggested that differences in metabolic activity found when comparing cell suspensions obtained by the use of different irritants are due to different proportions of the two cell types. In particular, the effects of oxygen tension and pH on the activities of the cells were studied. It was found that decreasing the proportion of oxygen in the atmosphere from that of air to 1 per cent reduced oxygen consumption by about 80 per cent, whereas lactic acid production was increased by about 45 per cent. It was also found that decreasing the pH of the medium below pH 7.5 caused a considerable reduction in the respiration, lactate production, and viability of polymorphonuclear leucocytes. The monocytes proved less sensitive to similar changes in pH, especially with regard to lactic acid production and viability. Observations were made of oxygen consumption and lactate production during phagocytosis. During the hour following the addition of heat-killed tubercle bacilli to the phagocytes, the oxygen consumption of suspensions rich in polymorphonuclear leucocytes rose by 60 per cent, and that of suspensions rich in monocytes rose by nearly 100 per cent. Lactic acid production was unchanged during phagocytosis.

Animals↗
PubMed1956

Studies on the interaction between phagocytes and tubercle bacilli. II. The action of phagocytes upon C14-labelled tubercle bacilli.

Tubercle bacilli labelled with C(14) were prepared by growth on radioactive substrates such as glycerol, CO(2), and acetate. These organisms were exposed in vitro to leucocytes (mostly polymorphonuclear leucocytes) from peritoneal exudates of guinea pigs. The respiration of the leucocytes and of the bacilli, alone and together, was followed by determining oxygen uptake and C(14)O(2) production. When heat-killed labelled tubercle bacilli were exposed to leucocytes there was little or no degradation of bacillary material to C(14)O(2) by leucocytic enzymes. On the other hand, conversion of components of sonically disrupted bacilli to C(14)O(2) by leucocytes was significant. It was possible to determine the oxygen uptake and C(14)O(2) production of phagocytized living tubercle bacilli, and it was found that after phagocytosis the bacilli maintained their rates of oxygen consumption and C(14)O(2) production. This finding was in contrast to observations made with Mycobacterium phlei, a saprophytic acid-fast organism, and with Bacillus subtilis. In these cases oxygen consumption and C(14)O(2) production declined after phagocytosis, and bacterial components were converted to carbon dioxide to a significant degree by leucocytic enzymes.

Animals↗