Determination of plasmalogen contents of phospholipid classes by reaction micro-thin-layer chromatography

Microfluidic Paper-Based Analytical Devices (μPADs) and Micro Total Analysis Systems (μTAS): Development, Applications and Future Trends

Microfluidic paper-based analytical devices and micro total analysis systems are relatively new group of analytical tools, capable of analyzing complex biochemical samples containing macromolecules, proteins, nucleic acids, toxins, cells or pathogens. Within one analytical run, fluidic manipulations like transportation, sorting, mixing or separation are available. Recently, microfluidic devices are a subject of extensive research, mostly for fast and non-expensive biochemical analysis but also for screening of medical samples and forensic diagnostics. They are used for neurotransmitter detection, cancer diagnosis and treatment, cell and tissue culture growth and amplification, drug discovery and determination, detection and identification of microorganisms. This review summarizes development history, basic fabrication methods, applications and also future development trends for production of such devices.

Mass spectrometry of fatty aldehydes

Fatty aldehydes are important components of the cellular lipidome. Significant interest has been developed towards the analysis of the short chain α,β-unsaturated and hydroxylated aldehydes formed as a result of oxidation of polyunsaturated fatty acids. Multiple gas chromatography-mass spectrometry (GC/MS) and subsequently liquid chromatography-mass spectrometry (LC/MS) approaches have been developed to identify and quantify short-chain as well as long-chain fatty aldehydes. Due to the ability to non-enzymaticaly form Schiff bases with amino groups of proteins, lipids, and with DNA guanidine, free aldehydes are viewed as a marker or metric of fatty acid oxidation and not the part of intracellular signaling pathways which has significantly limited the overall attention this group of molecules have received. This review provides an overview of current GC/MS and LC/MS approaches of fatty aldehyde analysis as well as discusses technical challenges standing in the way of free fatty aldehyde quantitation.

Quantitative analysis of phospholipids and demonstration of plasmalogen in human neutrophil subcellular fractions by high-performance liquid chromatography

The subcellular distribution of phospholipids in unstimulated neutrophils was investigated by high-performance liquid chromatography of lipid extracts of granule and plasma membranes obtained from Percoll density gradients. The mobile phase contained acetonitrile:methanol:85% phosphoric acid (131:3:0.8 v/v/v). Post-nuclear supernatants contained 2.3 micrograms lipid phosphorus/mg protein. Phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine and phosphatidylcholine were demonstrated in azurophil granules, specific granules and in a combined fraction of secretory granules and plasma membranes. Separate estimates of each phospholipid class by peak areas obtained by high-performance liquid chromatography showed that secretory granules and plasma membranes contained most of the phosphatidylinositol and phosphatidylcholine (p less than 0.005 vs peaks areas obtained in azurophil and specific granules), whereas a major part of the phosphatidylethanolamine was located in the specific granules (p less than 0.005 vs peak areas obtained in azurophil granules, and plasma membrane and secretory granules). High-performance liquid chromatography proved to be a useful principle for the demonstration of plasmalogen because the acidic solvent caused hydrolysis of phosphatidalethanolamine, which was recovered as lysophosphatidylethanolamine. Additionally, sphingomyelin was demonstrated in all subfractions by thin-layer chromatography.

Quantification of plasmalogen, alkylacyl and diacyl glycerophospholipids by micro-thin-layer chromatography

A method for the determination of plasmalogen, alkylacyl and diacyl glycerophospholipids based on mild alkaline deacylation and acid hydrolysis of plasmalogens on plates with subsequent micro-thin-layer chromatography on silica gel is presented. It is effective in quantifying alkyl and alkenyl analogues of phosphatidylethanolamine and phosphatidylcholine at concentrations up to 0.1% (of the total of the forms in individual classes of phospholipids.

The effect of fetal urine on arachidonic acid metabolism in human amnion cells in monolayer culture

Human amnion cells in primary monolayer culture were used as a model system to evaluate the regulation of arachidonic acid metabolism and prostaglandin E2 production in amnion. Amnion cells were incubated with carbon 14-labeled arachidonic acid, and after various times the distribution of radiolabeled arachidonic acid in the lipids of these cells were determined. After incubation for 72 hours, 91% of the total radiolabeled arachidonic acid incorporated into cellular lipids was present in glycerophospholipids, and 9% was present in neutral lipids. The formation of [14C]prostaglandin E2 from [14C]arachidonic acid was maximal after 8 hours. In these studies the effect of human fetal urine on arachidonic acid metabolism in these cells was investigated (the production of prostaglandin E2 by amnion cells is increased by treatment with fetal urine). In cells incubated with [14C]arachidonic acid in the incubation medium, treatment with fetal urine for 4 hours caused a threefold to fourfold increase in [14C]prostaglandin E2 production, yet there were no detectable differences in the content of [14C]arachidonic acid in specific glycerophospholipids or neutral lipids of the cells after such treatment. In other studies, amnion cells were preincubated for 72 hours with [14C]arachidonic acid, and thereafter the cells were treated with fetal urine for 24 hours. With fetal urine treatment the amount of [14C]arachidonic acid in triacylglycerols decreased significantly compared with that in nontreated cells, but the formation of [14C]prostaglandin E2 was not increased. Thus we suggest that in response to fetal urine, prostaglandin E2 is formed from arachidonic acid that is released from a highly specific, stimulus-sensitive lipid pool or else from arachidonic acid that is derived from extracellular sources.

Metabolism of arachidonic acid and prostanoids in human endometrial stromal cells in monolayer culture

In the present investigation, we compared the metabolism of arachidonic acid in human endometrial stromal cells maintained in monolayer culture with that in human decidual tissues. By gas-chromatographic analysis, the distribution of arachidonic acid in glycerophospholipids and in the neutral lipids of decidual tissues and stromal cells in culture was similar. After the addition of [14C]arachidonic acid to the culture medium, steady-state conditions with respect to radioactive labeling of the lipids of the cells were attained after 24 h, except for phosphatidylethanolamine and neutral lipids. The percentage distribution of [14C]arachidonic acid in the lipids of the cells in culture was as follows: phosphatidylcholine, 41%; phosphatidylserine, 5%; phosphatidylinositol, 19%; phosphatidylethanolamine, 22%; neutral lipids, 11%. This distribution of arachidonic acid among the lipids is similar to that in decidual tissue, except for that in phosphatidylethanolamine. The amount of radioactivity in phosphatidylethanolamine continued to increase up to 72 h whereas that in neutral lipids declined after a maximum amount was present at 4 h. In the cells in monolayer culture, [14C]prostaglandin E2 and [14C]prostaglandin F2 alpha were produced from [14C]arachidonic acid, as is true in superfused decidual tissue. The similarities in arachidonic acid metabolism in these cells to that in decidual tissue are supportive of the proposition that endometrial stromal cells in monolayer culture are an appropriate model for the study of the regulation of arachidonic acid release and prostaglandin formation by endometrium and decidua vera.

Lipid adaptation in liver mitochondrial membranes of carp acclimated to different environmental temperatures: phospholipid composition, fatty acid pattern and cholesterol content

The lipid fraction of liver mitochondria has been studied in carp acclimated to high and low environmental temperatures. Evidence is provided for a temperature-induced lipid adaptation which might control membrane fluidity. This supports suggestions made in a recent communication on temperature-induced changes in the Arrhenius functions of mitochondrial oxidase systems from carp liver ((Wodtke, E. (1976) J. Comp. Physiol. 110, 145--157). The results of the analysis of lipid composition are: the ratio of phospholipid to protein does not differ at cold and warm acclimation temperatures. Fish kept at low environmental temperature show a decreased molar ratio of cholesterol : phospholipid in mitochondrial membrane lipids; the diminished complexation renders phospholipids more sensitive to fluidity control by fatty acid substitution. A decrease of mitochondrial phosphatidylcholine at low acclimation temperature is observed, which is compensated by increased amounts of phosphatidylethanolamine and phosphatidylinositol. This means there is an increase in the acidic character of the phospholipids at low environmental temperature, and might be the cause of fluidization of the membrane and a decrease in transition temperature. The fatty acid pattern of carp mitochondria differs markedly from that of mammalian mitochondria; it is not identical for total lipids, phosphatidylcholine and phosphatidylethanolamine, and is roughly characterized by high amounts in n--3, but low amounts in n--6 and mono-unsaturated fatty acids. Low environmental temperature decreases the proportion of saturated species and markedly lowers the ratio of the alpha-linolenic acid family, the latter perhaps being caused by the increased activity of delta6-desaturase, as calculated for low acclimation temperature. An increase in mean unsaturation and in the proportion of 1,2-diunsaturated phospholipids most probably increases membrane fluidity at low acclimation temperature.