Theodor Von Brand

Cultural and physiological observations on Trypanosoma rhodesiense and Trypanosoma gambiense.

The cultivation of the trypanosomes of the brucei group is generally conceded to be much more difficult than that of the members of the lewisi group. While the latter have been cultivated in a variety of media and have been studied to some extent from the standpoint of their nutritional requirements and metabolic activities (Lwoff, 1940; von Brand, Johnson, and Rees, 1946; Chang, 1948), the cultivation of the former has been less successful, and therefore very little physiological information is available concerning them. Reichenow (1937b) stated that the addition of sugar did not improve his medium for the cultivation of the pathogenic trypanosomes. von Brand and Johnson (1947) found that the respiration of the proventricular form of T. gambiense was sensitive to cyanide. This is in contrast to that of its bloodstream form. Three types of media have given some measure of success in the cultivation of the pathogenic African trypanosomes. On blood agar media they grow either in the water of condensation (Novy and McNeal, 1904; Thomson and Sinton, 1912), or form colonies on the surface of the agar (Weinman, 1946). In liquid media (von Razgha, 1929; Reichenow, 1932, 1934; Brutsaert and Henrard, 1938) they aggregate commonly on the surface of the settled red cells. Slightly more viscous media were developed by Ponselle (1924) and Weinman (1944). They did not indicate where growth occurs in this type of medium. Most investigators use human blood as the blood of choice in the preparation of their media. Those who have used animal blood (Thomson and Sinton, 1912; Reichenow, 1932; Ponselle, 1924; Prates, 1928) did not present data which indicate whether such blood will sustain subcultivation for an indefinite period. In the first section of this paper we describe a diphasic blood agar medium which incorporates a number of features from the above media. It is less difficult to prepare than Weinman’s (1946) medium which it resembles in several respects. The remarkable intensity of sugar consumption by the bloodstream form of the pathogenic African trypanosomes (Yorke, Adams, and Murgatroyd, 1929; von Brand, 1933; Chen and Geiling, 1945; von Brand and Tobie, 1948) suggested the desirability of quantitative studies on sugar utilization by culturestages of these species. The data concerning this point, as well as data on the ammonia production, are summarized in the second section of this paper. 1. CULTURAL OBSERVATIONS Media employed

PHYSIOLOGICAL OBSERVATIONS ON STARVATION AND DESIC CATION OF THE SNAIL AUSTRALORBIS GLABRATUS

Laboratory-reared albino Australorbis glabratus, derived from a normally pig mented Venezuelan strain, were used in preference to pigmented specimens because the heart-beat could easily be seen through the shell. This was important, not only because a study of the heart rate under desiccation was interesting in itself, but also in order to establish whether a snail was alive or dead. The usual procedure of placing a desiccated snail in water to observe whether it resumes its normal activities could not be employed because in most of our experiments repeated measurements with the same specimens were required, or because a chemical determination had to be made on desiccated specimens. Most of the snails that appeared dead, as judged by cessation of the heart-beat, were tested further by placing them in water. Of about 200 such snails, only three revived, indicating that our death criterion was reasonably accurate. All snails initially weighed between 180 and 350 mg. and had fed ad libitum. They were freed of excess moisture as described previously (Newton and von Brand, 1955) and weighed to the nearest mg. During starvation, snails (minimum of 28 per series) were kept individually in numbered beakers filled with dechlori nated tap water. They were shifted daily to fresh beakers during the first week of starvation and thereafter twice weekly. During desiccation, snails (minimum of 1 Laboratory of Tropical Diseases.

RELATIONS BETWEEN PRE- AND POST-ANAEROBIC OXYGEN CONSUMPTION AND OXYGEN TENSION IN SOME FRESH WATER SNAILS

1. The respiration of four species of fresh water snails was somewhat dependent on the oxygen tension below 21 per cent oxygen with only minor differences among the various species.2. The degree of dependency was influenced little, if any, by alteration of the metabolic rate of Australorbis glabratus, but some changes were obtained in the cases of Helisoma duryi and Lymnaea stagnalis.3. All species showed a long lasting respiratory rebound after 16 hours anaerobiosis. The post-anaerobic respiration was more dependent on the oxygen tension than the pre-anaerobic respiration if referred to the normal rate shown at 21 per cent oxygen. But if the post-anaerobic rates were compared with the rates sustained pre-anaerobically at an identical oxygen tension, an approximately equal percentage increase was observed over a wide range of tensions.4. The implications of these observations and auxiliary observations dealing with the rate of the heart-beat under various conditions are discussed insofar as they shed ligh...

Der Stoffwechsel der Parasiten

Parasiten kbnnen den Wilt in mannigfacher Weise sch~[digen. H~ufig sind es mechanische Sch~den. Wenn sich z.B. eine Echinococcus-Cyste ill einem lebenswichtigen Organ wie dem Gehirn entwickelt, steht eine mechanische Sch~digung der Wirtsgewebe wahrscheinlich im Vordergrund des pathologischen Geschehens. Wit wollen uns dagegen die Frage vorlegen, in welcher Weise chemische, im Parasiten ablaufende Prozesse den Wilt sch~digen kbnnen. Uns interessiert, ob der Stoffwechsel der Parasiten einen EinfluB auf den Wilt hat und ob Heilmittel ihre Wirkung dutch Beeinflussung des Stoffwechsels des Parasiten austiben. Der Stoffwechsel praktisch aller Parasiten ist ein G~rungsstoffwechsel, mag es sich um reine oder fast reine anaerobe G~rungsvorg~nge handeln. Sie kommen tiberall da vor, wo Parasiten in sauerstofffreier Umwelt leben, oder wo Parasiten in sehr sauerstoffarmer Umwelt nicht dazu bef~higt sind, ihrer Urnwelt grbBere Sauerstoffmengen zu entziehen. Beispiele sind groBe Rundwiirmer wie Ascaris oder grofie Bandwfirmer wie Moniezia, die das sauerstoffarme Darmlumeu bewohnen. G~rungsstoffwechsel sind jedoch nicht auf solche Parasiten beschr~nkt. Protozoen und Wt~rmer, die in an sich recht sauerstoffreicher Umgebung (wie dem Blute) leben, oder die Gewebe parasitieren, deren Wirtszellen gent~gend Sauerstoff enthalten, kbnnen eine recht ausgesprochene Sauerstoffzehrung haben, trotzdem aber grbBere Mengen nur teilweise oxydierter Stoffwechsel-Elldprodukte ausscheiden.