Addition Of Deoxycholate Research Articles

Inhibition of microsomal triphosphopyridine nucleotide-cytochrome c reductase.

DURING certain work on the distribution and pathways of pyridine nucleotide oxidation in microsomal systems from rat liver, it was found that the oxidation of reduced triphosphopyridine nucleotide (TPNH) was associated with the ribonucleoprotein particle fraction, as well as with microsomes from which the particles were derived. The specific activity of the TPNH oxidation is similar in the microsome and ribonucleoprotein particle fractions. Moreover, the addition of deoxycholate to microsomes or derived particles did not alter TPNH–cytochrome c reductase activity. However, it was discovered that the rate of oxidation of TPNH progressively declined with time.

Attempts at Interspecies Genetic Transfer in Trypanosomes

Ever since the work of Avery, MacLeoud and McCarty (1944, J. Exp. Med. 79: 137-157) there has been considerable interest in genetic transfer via nucleic acid macromolecules into the genome of a recipient cell. Successful genetic transformation has been accomplished since on many occasions among the bacteria. In addition, Fulton (1960, Rutgers Biol. Symp. Host. Infl. on Parasite Physiol., pp. 11-23), Honigberg and Read (1960, Science 131: 352-354) and Inoki and Matsushira (1960, Biken's J. 3: 101-106) have reported on what appears to be nucleic acid mediated intra species genetic transfer among trypanosome and trichomonad flagellates. The present note reports on attempts to effect nucleic acid mediated genetic transformation between two different species of trypanosomes, i.e., data on inter species transformation. The Tulahuen strain of Schizotrypanum cruzi was mass-cultured in a modified Chang's diphasic medium (Chang, 1947, J. Inf. Dis. 80: 164-171). After centrifugation and washing with buffered saline, culture forms of S. cruzi were lysed by addition of deoxycholate, ultrasonic disintegration, or by repeated freeze-thawing. Nucleic acids were extracted following the methods of Hotchkiss (1957, Methods in Enzymology, Vol. III, Acad. Press). For preparations of DNA alone, RNAse was added to remove RNA. In either case the nucleic acids were precipitated with ethanol and stored in small quantities of saline. Blood stream forms of Trypanosoma lewisi were obtained by cardiac puncture from laboratory rats having been given T. lewisi by i.p. injection 4 to 10 days previously. A small quantity of S. cruzi nucleic acid preparation was added to either the citrated T. lewisi-infected rat blood or to a buffered saline Armour Plasma Fraction V medium to which washed T. lewisi were added. The live

In vitro studies of human plasma lipolytic activity before and after oral fat intake.

The rate of in vitro lipolysis of added human low density lipoproteins was determined in 22 normal individuals using fasting and lipemic plasma. Unesterified fatty acid release was found in 16 subjects in all, in 10 in the fasting plasma and in 14 in the postlipemic plama. Lipolytic activity was greater in the lipemic sample in eight of the 16 individuals, in three it was unchanged before or after fat intake, and in five it was higher in the fasting sample. Addition of deoxycholate, which decreases heparin clearing factor and increases pancreatic lipase activity, inhibited lipolysis in most of the subjects and increased it in a few. Studies using beta-naphthol laurate, which in the presence of taurocholate is an excellent substrate for human pancreatic lipase but not for postheparin lipolytic activity, showed no hydrolysis in eight subjects, in six of whom lipolysis of the lipoproteins occurred. The results of the study suggest that increased plasma lipolytic activity is sometimes present after the ingestion of fat. They further indicate that endogenous heparin lipoprotein lipase is the major plasma enzyme involved in the splitting of neutral fat, but that a lipase similar to pancreatic lipase may be present less frequently, in small amounts, and may require added bile for activity. Submitted on February 20, 1957