Rate Of Lipid Synthesis Research Articles

Lipid synthesis in human leucocytes in acute leukaemia.

SUMMARYLipid synthesis in human leucocytes was examined in vitro in blood from patients with acute leukæmia and from normal controls, acetate being used as substrate. The incorporation of acetate‐1‐C14 was measured in total lipids, neutral lipids and phospholipids of the leucocytes and plasma. Both morphological types of acute leukæmia revealed trends away from the normal rates of total lipid synthesis, the rates being high in acute myeloid leukæmia and low in acute lymphatic leukæmia. Fractional lipid synthesis was similar to the normal in acute lymphatic leukæmia, but in the cells of acute myeloid leukæmia proportionally more radioactivity was incorporated into the phospholipid fraction. This difference was not reflected in the plasma‐phospholipid fraction. The changes in leucocyte lipid synthesis are discussed in relation to the mixed‐cell populations involved and to the question of cell age.

Effect of aging on lipid composition and metabolism in the adipose tissues of the rat

Lipid metabolism and chemistry was studied in adipose tissues of the rat from the age of 38 days to 647 days. Aging process was characterized by a marked decrease in lipid synthesis from acetate, a reduction in the proportion of glucose metabolized by the pentose phosphate pathway, and a lower rate of palmitate incorporation into the mixed lipids. Oxidation of palmitic acid to CO2 and release of free fatty acid by epididymal fat was the same in young and old tissues under control conditions; when, however, glucose was absent from the medium or when epinephrine was added, there was a significantly greater rate of palmitic acid oxidation and free fatty acid release by young compared to old adipose tissue. Rate of acetate incorporation into mixed lipids by multiple adipose tissue sites was determined at different ages. Consistently greater rates of lipid biosynthesis were found in the epididymal, perirenal, mesenteric and interscapular adipose tissues than in subcutaneous fat at all ages. Rate of lipid synthesis by the interscapular fat (unlike any of the other depots) remained high at all ages studied. A greater proportion of short chain fatty acids was found in adipose tissues from young rats than in the old. This was related to fatty acid composition of rat milk.

Rates of acetate turnover and lipid synthesis in normal, hypothyroid and hyperthyroid rats.

Sodium acetate-1-C14 was administered to anesthetized rats by continuous intravenous infusion, with simultaneous administration of d,l-α-amino-γ-phenylbutyric acid. Radioactivity measurements were made of respiratory CO2, cholesterol, fatty acids and urinary acetylamino acid. From the radioactivity data, calculations were made of rates of acetate turnover and of synthesis of cholesterol and fatty acids from acetate. Data on these metabolic functions are given for normal rats on a stock diet and for animals on a lipid-free ration. Similar experiments were carried out in rats fed thyroid powder and thiouracil. The rate of acetate turnover, and rates of synthesis of cholesterol and fatty acids from acetate, were found to be directly proportional to the basal oxygen consumption rates of the animals. The altered rates of lipid synthesis from acetate resulted, in the main, from absolute changes in rates of the reactions involved, and only to a small extent from shifts in the relative magnitudes of different pathways of acetate metabolism.

Factors Affecting the Production of Carotene by Choanephora Cucurbitarum

SUMMARYMixed + and - cultures produced 3 to 5 times as much carotene as either isolate produced when grown alone. Increasing the glucose concentration from 20 to 80 g/l more than doubled the carotene yield from mixed + and - cultures; this increase in glucose concentration resulted in an insignificant increase in carotene production when the + and - isolates were grown separately. Hexoses (glucose, mannose, and galactose) were the best carbon sources for carotene production by mixed + and - cultures. Glutamic acid was the best nitrogen source. The lipid content of the mycelium increased as the glucose content of the medium increased; the lipid content was approximately 50 per cent when the medium contained 100 g/1 of glucose. Carotene synthesis continued for several days after the glucose was utilized; the lipid content decreased after the glucose was exhausted. The addition of potassium acetate to 3-day-old cultures grown on the basal medium increased carotene production somewhat. Experiments with acetate-1-C14 showed that acetate was utilized. beta-Ionone stimulated carotenogenesis markedly when it was added to half-grown + and - cultures; it was relatively ineffective when added to separate cultures of either isolate. In addition, beta-ionone inhibited growth, decreased the rate of glucose utilization and lipid synthesis, reduced the rate of respiration, and delayed zygospore formation and maturation. Yields of carotene slightly in excess of 7 mg/g dry mycelium were obtained from 4-day-old cultures grown on a molasses-glutamic acid medium and which were treated with 5 μl of beta-ionone per culture on the second day of incubation.

The effect of x-irradiation and glucose on brain lipid synthesis.

Abstract1. — Rat X-irradiation induces an increase in the rate of cholesterol and fatty acid biosynthesis from l-14C acetate, but has an inhibitory effect on brain lipid biosynthesis.2. — Cholesterol and fatty acid biosynthesis from 2–14C mevalonic. acid is slightly increased by X-irradiation in the liver, but is unchanged in the brain.3. — Glucose added to the incubation medium (10 micro M./ml.) increases the rate of lipid synthesis in the brain, to a greater extent than in the liver and has a marked effect on mevalonic: acid incorporation into brain lipids.4. — The effect of X-irradiation is not modified by increasing the levels of liver and brain glucose.