Highly unsaturated fatty acids. III. Isolation of methyl eicosapentaenoate,ethyl docosapentaenoate,and ethyl docosahexaenoate from cod liver oil esters by chromatography

a) Displacement chromatography using a charcoal-isopropanol-methyl behenate system has been successfully applied to the isolation of docosahexaenoic acid and ethyl docosahexaenoate from cod liver oil concentrates. b) Methyl eicosapentaenoate was isolated from cod liver oil methyl esters by combined elution chromatography on silicic acid and displacement chromatography. c) Using silicic acid as adsorbent and petroleum ether-chloroform as solvent, ethyl docosapentaenoate was isolated from cod liver oil ethyl esters. d) With a spinning band fractionation column it was found that fractional distillation of methyl esters of cod liver oil at 0.5 mm. Hg. resulted in increasing conjugation in the distillate as the fractionation proceeded. Fractional distillation is to be avoided as a final step in purification of polyunsaturated esters. e) The end absorption of conjugated pentaenoic acids is so large at the characteristic maximum for hexaene (3,750 Å) that simultaneous equations are required for the calculation of hexaenoic and pentaenoic acids. f) Fifteen minutes of treatment with 21% KOH-ethylene glycol at 180° is not optimum for isomerization of ethyl docosapentaenoate from cod liver oil. The optimum isomerization times for hexaenoic acids of various sources are 4 to 6 minutes, considerably different from the 15 minutes established for arachidonate.     

Characterization of unsaturated fatty acids by gas-liquid chromatography

The equivalent chain length (ECL) has been determined on 79 methyl esters of unsaturated fatty acids and on 7 ethyl esters by gas chromatography. Ethylene glycol succinate (EGS), diethylene glycol succinate, β-cyclodextrin acetate and Apiezon L were chosen as the liquid phases to be used. For methyl esters of mono- and polyenoic acids, the differences between ECL on EGS and ECL on Apiezon L approximate 0.84 per double bond. For positional isomers, the ECL on both EGS and Apiezon L are usually greater for the isomer having the longer proximal end of the molecule (smallest ω value). In these terms a triple bond is approximately equal to three double bonds. Esters of nonconjugated dienoic and trienoic acids of the same chain length are not separable on Apiezon L if their proximal structures are the same. This also applies to tetraenoic and pentaenoic acids of the same chain length and the same proximal structure. Conjugation of double bonds, either with the ester carbonyl group or with themselves, yields ECL values on Apiezon L greater than the number of carbon atoms in the acid. Monounsaturated and nonconjugated polyunsaturated esters have ECL values on Apiezon L lower than the number of carbon atoms of the acid. The ECL values of ethyl esters of 18 and 20 carbon acids are greater than the corresponding methyl esters on Apiezon L. Presented at the Chicago meeting of the American Oil Chemists’ Society, Oct. 13, 1964.     

Comparative analytical studies of fatty acids of the algaChlorella pyrenoidosa

Gas-liquid chromatography, several versions of paper chromatography, and alkaline isomerization have been applied to one preparation ofChlorella fatty acid methyl esters. GLC outranks other methods in rapidity, reproducibility, and resolving power. The presence of nonvolatile components in the sample can lead to erroneous results. Among PC methods which might arise from autoxidation and polymerization are detected. Esters or acids with 14 or fewer C atoms should be analyzed as nonvolatile derivatives. AI, as used here, introduces a systematic error in the determination of linoleic and linolenic acids. The quantitative results of the methods are in agreement for the major components, which all belong to the C₁₀ and C₁₈ series. A number of minor components have been revealed by GLC and/or PC. They are tentatively identified as <C₁₂, C₁₂, four C₁₄, C₁₅, two C₁₇, C₁₉, three C₂₀, two C₂₂, and C₂₄ acids. Several of these compounds have been found independently by different methods in hydrogenated form or as radioactive esters. This enhances the certainty of their identification. Eurichment by fractional distillation was essential for their detection. Possible losses in their distillation and other considerations make uncertain the assay of most of the minor components by GLC or PC. Work supported in part by grant RG-4226 from the Division of General Medical Sciences of the U. S. Public Health Service and in part by the Hormel Foundation.     

The rates of oxidation of unsaturated fatty acids and esters

The rates of autoxidation of oleic acid, ethyl oleate, linoleic acid, 10,12-linoleic acid, ethyl linoleate, trilinolein, pentaerythritol linoleate, dipentaerythritol linoleate, elaidolinolenic acid, linolenic acid, ethyl linolenate, trilinolenin, and methyl arachidonate have been studied by oxygen uptake in a Warburg respirometer and the results are compared with the rates of enzymatic oxidation of lipoxidase substrates. The increase in the number of double bonds in a fatty acid by one increases the rate of oxidation of the fatty acid or its esters by at least a factor or two. Earlier findings that acids oxidize more rapidly than their esters have been confirmed. The initial rates of lipoxidase oxidation of ethyl linoleate, ethyl linolenate, and methyl arachidonate were found to be essentially the same.     

Automated immunomagnetic separation and microarray detection of E. coli O157:H7 from poultry carcass rinse.

We describe the development and application of an electromagnetic flow cell and fluidics system for automated immunomagnetic separation (IMS) of Escherichia coli O157:H7 directly from poultry carcass rinse. We further describe the biochemical coupling of automated sample preparation with nucleic acid microarrays. Both the cell concentration system and microarray detection method did not require cell growth or enrichment from the poultry carcass rinse prior to IMS. Highly porous Ni foam was used to enhance the magnetic field gradient within the flow path, providing a mechanism for immobilizing immunomagnetic particles throughout the fluid rather than the tubing wall. A maximum of 32% recovery efficiency of non-pathogenic E. coli was achieved within the automated system with 6 s cell contact times using commercially available antibodies targeted against the O and K antigens. A 15-min protocol (from sample injection though elution) provided a cell recovery efficiency that was statistically similar to > I h batch captures. O157:H7 cells were reproducibly isolated directly from poultry carcass rinse with 39% recovery efficiency at 10(3) CFU ml(-1) inoculum. Direct plating of washed beads showed positive recovery of O157:H7 directly from poultry carcass rinse at an inoculum of 10 CFU ml(-1). Recovered beads were used for direct polymerase chain reaction (PCR) amplification and microarray detection, with a process-level detection limit (automated cell concentration though microarray detection) of < 10(3)CFU ml(-1) in poultry carcass rinse.     

Single event transient effects in a voltage reference

The Single Event Transient response of the LM236 band gap voltage reference from Texas Instruments is analyzed through heavy ion experiments and simulation. The LM236 circuit calibration was performed using generic transistor parameters that were subsequently optimized using device and circuit simulations. This technique avoids the requirement for performing detailed device-level parameter extraction and simplifies the SET methodology for circuit calibration.     

Fatty acid pattern of tissue phospholipids in copper and iron deficiencies

Because copper and iron have been reported to be essential cofactors in Δ9 desaturation of fatty acids, the effects of different dietary intakes of copper and iron on tissue fatty acids were studied. Male Long-Evans rats (ten per group) were fed diets containing adequate, deficient or excess copper or iron. On day 42 of the dietary regimen, the animals were killed and tissues and blood were removed for analysis of metals and fatty acids of phospholipids. Compared with the copper-adequate rats, the copper-deficient rats showed increased 18∶0 in liver and decreased 16∶1ω7 in liver, heart and serum. There were no differences for 16∶0 or 18∶1ω9. Intake of excess copper did not cause an increase in products of Δ9 desaturation. Comparisons between iron-deficient and iron-adequate rats showed that iron deficiency increased 18∶2ω6 in liver and serum and decreased 20∶4ω6 in serum only. Relative percentages of 16∶0, 18∶0, 16∶1ω7 and 18∶1ω9 in liver and serum phospholipids were similar for both groups. Intake of excess iron caused a decrease in 18∶2ω6; and 16∶0 and 18∶1ω9 were higher in the liver of the iron-excess group than the iron-deficient group. This study did not support the requirement for copper or iron in the Δ9 desaturation of fatty acids as expressed in phospholipids of liver, heart and serum.     

Work characteristics, musculoskeletal disorders, and the mediating role of psychological strain: A study of call center employees.

The demands of the modern office are thought to contribute to the development of musculoskeletal disorders. For upper body and lower back disorders, these effects are hypothesized to be mediated by psychological strain. A study of 936 employees from 22 call centers supports this hypothesis. Using logistic regression and structural equation modeling, the authors found that the relationship of workload to upper body and lower back musculoskeletal disorders was largely accounted for by job-related strain. This mediating effect was less evident for arm disorders. Contrary to expectation, job autonomy had neither a direct nor a moderating effect on any musculoskeletal disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)