RESUMO
A protocol based on radio gas chromatography demonstrates that when HeLa cells are deprived of valine for short periods of time (6-7.5 h), their overall fatty acid biosynthetic activity is depressed after a latency of a few hours. The transfer of newly synthesized fatty acyl units to phospholipids is curtailed much faster than their transfer to triacyglycerols. Despite the cut-back in fatty acid biosynthesis, valine deprivation causes a lipid accumulation in the cells. Valine deprivation appears to affect de novo synthesis of fatty acid units from acetate more rapidly than desaturation and elongation. When valine is returned to the valine-deprived culture, overall fatty acid biosynthesis is resumed well within 2 h. Newly synthesized fatty acyl units are transferred to both the phospholipids and the 1,2-diacylglycerols of the cells but not initially to the triacylglycerols.
Assuntos
Ácidos Graxos/metabolismo , Células HeLa/metabolismo , Valina/metabolismo , Cromatografia Gasosa , Diglicerídeos/biossíntese , Células HeLa/efeitos dos fármacos , Cinética , Relação Estrutura-Atividade , Triglicerídeos/biossíntese , Valina/farmacologiaRESUMO
The effects that amino acid starvation and re-supplementation have on fatty acid metabolism in HeLa cells have been studied using radio gas chromatographic techniques. Deprivation of valine for 13.5 h caused fatty acid de novo biosynthesis, elongation and desaturation to cease. This effect was reversed within 5 h by adding valine back to the culture. During deprivation accumulation of triacylglycerol occurred. The return of valine to the culture caused compositional changes in the triacylglycerols and phosphatidylcholines.
Assuntos
Ácidos Graxos/metabolismo , Células HeLa/metabolismo , Valina/farmacologia , Cromatografia Gasosa , Células HeLa/efeitos dos fármacos , Fosfatidilcolinas/biossíntese , Triglicerídeos/biossíntese , Valina/metabolismoRESUMO
A method based on direct exposure, positive ion, chemical ionization mass spectrometry/mass spectrometry (ms/ms) was developed for the confirmatory assay of the antiparasitic drug, ivermectin, in animal tissue. Following extraction, column and preparative liquid chromatography, mass spectrometric/mass spectrometric analysis of the drug in liver samples provided reliable detection limits to 8-10 parts-per-billion at a signal: noise of greater than 10:1. Blank tissue consistently displayed no chemical/matrix interference. Besides the development of a confirmatory assay, the study also demonstrates the analytical capability and the role of MS/MS vis-a-vis other applied mass spectrometric techniques.