Remuneration disparities in Oceania: Papua New Guinea and Solomon Islands.

This paper explores the impact of remuneration differences on workers in the Solomon Islands and Papua New Guinea. In these countries remunerative differences are linked to government policy (in Papua New Guinea) and job contracts (in the Solomon Islands), and have impacted on industrial relations in both settings (strike action). A total of N = 350 professionals (n = 60 expatriates) from 54 organizations in aid, government, higher education and industry (mean response rate = 36%) responded to an organizational survey form.

Comparing different strategies for colorectal cancer screening in Italy: predictors of patients' participation.

Objectives: The objective of this study was to study predictors of patients' participation in colorectal cancer (CRC) screening.

Methods: Men and women, aged 55-64 years, were randomized to the following: (i) biennial fecal occult blood test (FOBT) delivered by mail (n=2,266); (ii) FOBT delivered by a general practitioner (GP)/screening facility (n=5,893); (iii) "once-only" sigmoidoscopy (FS) (n=3,650); (iv) FS followed by FOBT for screenees with negative FS (n=10,867); and (v) patient's choice between FS and FOBT (n=3,579). A stratified (by screening arm) random sample of attenders and nonattenders was contacted by trained interviewers 4 months after the initial invitation.

Elution factors of synthetic oxotriacylglycerols as an aid in identification of peroxidized natural triacylglycerols by reverse-phase high-performance liquid chromatography with electrospray mass spectrometry.

Selected elution factors were determined for model oxotriacylglycerols as an aid in identification of the peroxidation products of natural triacylglycerols by reverse-phase high-performance liquid chromatography (HPLC) with electrospray mass spectrometry (LC/ES/MS). For this purpose synthetic triacylglycerols of known structure were converted to hydroperoxides, hydroxides, epoxides, and core aldehydes and their dinitrophenylhydrazones by published procedures. The oxotriacylglycerols were resolved by normal-phase thin-layer chromatography and reverse-phase HPLC, and the identities of the oxotriacylglycerols confirmed by LC/ES/MS.

Isolation and identification of glycated aminophospholipids from red cells and plasma of diabetic blood.

Glycosylation is a major pathway for posttranslational modification of tissue protein and begins with nonenzymatic addition of carbohydrate to the primary amino groups. Excessive glycation of tissue protein has been implicated in the pathogenesis of diabetes and ageing. While glycation of aminophospholipids has also been postulated, glycated aminophospholipids have not been isolated.

Determination of lipid ester ozonides and core aldehydes by high-performance liquid chromatography with on-line mass spectrometry.

Unsaturated triacylglycerols (TG) and choline (PC) and ethanolamine (PE) phosphatides of known structure were subjected to ozonization and reduction with triphenylphosphine to yield the corresponding lipid ester core aldehydes. Mono- and di-C9 aldehyde palmitoylglycerols were prepared from oleoyldipalmitoyl and oleoyllinoleoylpalmitoyl glycerols, respectively, while egg yolk PC and PE provided the mono-C5 and mono-C9 aldehydes of palmitoyl-and stearoyl glycerophospholipids. The aldehydes were isolated in the free form and as the dinitrophenylhydrazone (DNPH) derivatives by thin-layer chromatography (TLC).

Preparation and characterization of glucosylated aminoglycerophospholipids.

Natural aminophospholipids were isolated from egg yolk and from human red blood cells. Glucosylated ethanolamine and serine phosphatides were prepared by exposing synthetic and natural aminophospholipids to glucose for 3-18 h at pH 7.4.

Lipid ester-bound aldehydes among copper-catalyzed peroxidation products of human plasma lipoproteins.

We have isolated the core aldehydes (aldehydes still bound to parent molecules) of phosphatidylcholine (PC) and cholesteryl esters (CE) from copper-catalyzed peroxidation of human plasma low (LDL) and high (HDL) density lipoproteins. The aldehydes were isolated by extraction with acidified chloroform-methanol containing 2,4-dinitrophenylhydrazine. The 2,4-dinitrophenylhydrazone (DNPH) derivatives formed were resolved by reversed phase high performance liquid chromatography (HPLC) and identified by on-line quadrupole mass spectrometry (LC/MS).

Plasma and urine enrichments following infusion of L-[1-13C]phenylalanine and L-[ring-2H5]phenylalanine in humans: evidence for an isotope effect in renal tubular reabsorption.

Amino acids labeled with 13C or deuterium are commonly used in studies of amino acid metabolism. Traditionally, amino acid flux has been estimated by measurement of isotopic enrichment in the plasma pool; however, urine sampling as a noninvasive means of determining isotope enrichment has been increasing. The isotope enrichments and fluxes estimated from plasma and urine sampling were compared when two phenylalanine tracers (L-[1-13C]phenylalanine and L-[ring-2H5]phenylalanine) were intravenously infused for 4 hours in seven healthy men.

Identification of core aldehydes among in vitro peroxidation products of cholesteryl esters.

Synthetic cholesteryl 5-oxovalerate and 9-oxononanoate were used as reference standards for the isolation and identification of cholesteryl ester core aldehydes from tert-butyl hydroperoxide/Fe++ oxidation of synthetic and natural cholesteryl esters. The core aldehydes were recovered from the peroxidation products by thin-layer chromatography as the free aldehydes or the 2,4-dinitrophenylhydrazones and were identified, respectively, by gas-liquid chromatography (GLC) and by GLC combined with mass spectrometry (GC/MS) or by reverse-phase high-performance liquid chromatography (HPLC) and by HPLC with MS (LC/MS). The core aldehydes produced by peroxidation of cholesteryl linoleate were identified as mainly 9-oxononanoates of cholesterol and oxycholesterols, with smaller amounts of the 8-oxooctenoates, 10-oxodecenoates, 11-oxoundecenoates and 12-oxododecenoates.

Identification of cholesterol-bound aldehydes in copper-oxidized low density lipoprotein.

Lipid-soluble cholesteryl ester core aldehydes (aldehydes still bound to the cholesterol ring) were identified among the products of copper-catalyzed peroxidation of human low density lipoprotein (LDL). The LDL was exposed to oxygenated buffer and 5 microM CuSO4 for 24 h. The core aldehydes were isolated as the dinitrophenylhydrazones, and were identified by reverse-phase HPLC with mass spectrometry.

Plasma lipid profiling by liquid chromatography with chloride-attachment mass spectrometry.

A sensitive high-performance liquid chromatographic assay was developed using chloride attachment negative chemical ionization mass spectrometry for detection of glyceryl esters and ceramides, and positive chemical ionization mass spectrometry for detection of free cholesterol and cholesteryl esters in minimal quantities of plasma. The novel technique was validated by high temperature gas-liquid chromatography with flame ionization detection. Sample preparation was achieved by phospholipase C digestion of whole plasma, total lipid extraction and derivatization of any free carboxyl and hydroxyl groups by trimethyl- or tert-butyldimethyl-chlorosilane.

HPLC resolution of diacylglycerol moieties of natural triacylglycerols on a chiral phase consisting of bonded (R)-(+)-1-(1-naphthyl)ethylamine.

Chiral phase high performance liquid chromatographic resolution of sn-1,2(2,3)- and X-1,3-diacylglycerols generated by partial Grignard degradation from natural triacylglycerols was carried out using a chiral column (25 cm x 4.6 mm i.d.

Identification of the more complex triacylglycerols in bovine milk fat by gas chromatography-mass spectrometry using polar capillary columns.

The fourth most volatile 2.5% molecular distillate of butteroil obtained by redistillation of the most volatile 10% cut was examined by gas chromatography on a polar capillary column (RSL-300) with electron impact and chemical ionization mass spectrometry. For this purpose the distillate was first freed from the acetyldiacylglycerols by thin-layer chromatography on plain silica gel and the remainder resolved into long and short chain length saturates, cis- and trans-monoenes, dienes and trienes by thin-layer chromatography on silver nitrate-silica gel.

Stereochemical course of intestinal absorption and transport of mustard-seed oil triacylglycerols in the rat.

Male rats with thoracic duct cannulae were intubated with mustard-seed oil or the corresponding fatty acid methyl esters and the lymph was collected over 0-24 h. The chylomicron and very low density lipoprotein fractions were obtained by conventional ultracentrifugation. The triacylglycerols and glycerophospholipids were isolated and the positional distribution and molecular association of fatty acids were determined by stereospecific and chromatographic methods.

Usefulness of gas chromatographic profiles of plasma total lipids in diagnosis of phytosterolemia.

A Cambodian male (aged 5 years and 9 months) presented with subcutaneous and tendon xanthomas in association with hypercholesterolemia. He was erroneously diagnosed as having familial hypercholesterolemia and treated with a low cholesterol diet (+/- cholestyramine) to which he did not respond. A determination of plasma total lipid profile by high-temperature gas chromatography revealed elevated plasma levels of free and esterified plant sterols along with the hypercholesterolemia.

Fatty acid composition of individual plasma steryl esters in phytosterolemia and xanthomatosis.

The bulk of the plasma plant sterol in phytosterolemia occurs in the esterified form and is carried mostly in the low and high density lipoproteins. We have determined the fatty acid composition of the individual plasma steryl esters from a newly discovered subject with phytosterolemia and xanthomatosis. For this purpose the intact steryl esters were subject to high temperature gas liquid chromatography (GLC) on a polar capillary column, which separated the major esters on the basis of molecular weight and degree of unsaturation of the fatty acids.

Stereospecific analysis of fatty acid esters of chloropropanediol isolated from fresh goat milk.

The fatty acid esters of chloropropanediol isolated from goat milk fat in small quantities were subjected to a stereospecific analysis via phospholipase C and phosphocholine esters as intermediates. Synthetic rac-1-chloro-2,3-dioleoyl-propanediol was prepared by standard methods and was used as a control. The stereospecific analyses were performed following a release of the fatty acids from the primary positions of each chloropropanediol diester with pancreatic lipase.

Simultaneous analysis of low plasma levels of deuterium-labeled saturated and unsaturated fatty acids as t-butyldimethylsilyl esters.

A sensitive and accurate method for detection and quantitation of deuterated fatty acids in the presence of large amounts of unlabeled fatty acids is described using mass fragmentography in combination with the preparation of tertiarybutyldimethylsilyl esters (t-BDMS). The method has been applied to determination of deuterated stearic, oleic, elaidic and linoleic acids in human plasma lipoproteins following duodenal perfusion with a micellar mixture of acids. Over a concentration range of 10-1000 ng/ml, the average coefficient of variation for the linoleate was 3% and for the oleate (elaidate) ester was 2%.

Comparative study of the molecular species of chloropropanediol diesters and triacylglycerols in milk fat.

In an effort to establish the origin of the fatty acid esters of 3-chloropropanediol, which recently have been isolated in small amounts from goat milk, we compared the molecular species composition of the chlorohydrin diesters and of goat milk triacylglycerols. The chloropropanediol diesters were found to be composed of molecular species containing C10-C18 fatty acids and corresponded closely in carbon number to those calculated for the long chain sn-1,2-diacylglycerol moieties of goat milk triacylglycerols. The molecular species of goat milk total triacylglycerols contained C4-C18 fatty acids.

Deacylation of endogenously deuterated rat liver microsomal phospholipids by endogenous phospholipases.

The relative deacylation of microsomal phospholipid molecular species was reexamined. Microsomal membranes were prepared from the livers of rats injected, over a period of 20 h, with perdeuterated ethanol. The phosphatidylcholine and phosphatidylethanolamine were isolated by thin-layer chromatography of the total lipid extracts and the distribution of deuterium among the molecular species of the diacylglycerol moieties was determined by reversed-phase high pressure liquid chromatography in combination with chemical ionization mass spectrometry.

Quantitation of natural triacylglycerols by reversed-phase liquid chromatography with direct liquid inlet mass spectrometry.

Using acetonitrile and propionitrile as eluting solvents and reagent gases the yields of both quasi-molecular and fragment ions were found to vary with the molecular weight, degree of unsaturation and positional distribution of the fatty acids in the triacylglycerol molecule, and appropriate calibration factors were necessary for accurate quantitation. In the absence of pure structural isomers and mixed acid standards, preliminary calibration factors have been determined for total ion and specific ion current responses by comparing the peak area ratios obtained by liquid chromatography-mass spectrometry with the proportions of the molecular species known to be present in randomized oils and in natural oils of known chemical composition. Although the derived factors include both chromatographic and mass spectrometric effects and are obtained with a gradient of reagent gases, they appear to be generally applicable.

Simultaneous quantitation of Krebs cycle and related acids by mass fragmentography.

Methods are described for simultaneous quantitation of Krebs cycle and related acids by gas chromatography--mass spectrometry using deuterium-labelled acids and n-butyl-d9-esters of the organic acids as internal standards. Using sulphuric acid as esterification catalyst, only lactic, succinic, fumaric, malic, maleic and citric acids were found to be stable to hydrogen exchange and could be used as reference standards in the deuterated form. In contrast, pyruvic, oxalacetic, alpha-ketoglutaric and malonic acids were found to exchange their deuterium readily and could not be employed for this purpose.

Analysis of triacylglycerols by reversed-phase high pressure liquid chromatography with direct liquid inlet mass spectrometry.

Natural triacylglycerols were resolved by high pressure liquid chromatography on Supelcosil LC-18 columns using a gradient of 30-90% propionitrile in acetonitrile as eluting solvent. The effluent was admitted to a quadrupole mass spectrometer via a direct liquid inlet interface. The mass spectra of the solutes were recorded in the chemical ionization mode.

Strategy of glycerolipid separation and quantitation by complementary analytical techniques. Plenary lecture.

Although improved systems for chromatographic resolution continue to be developed there is good reason to believe that no single method will be capable fo complete separation of all lipid mixtures including the geometric, positional and stereochemical isomers in each molecular species. Furthermore, the chromatographic systems giving the highest resolution usually yield the least complete recoveries of components and require separate procedures of quantitation. It is therefore necessary to develop appropriate strategies that yield the required resolution as a result of consecutive application of complementary analytical techniques.