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R J Pawlosky

Publications and source records attributed to R J Pawlosky.

At least 19 recordsLinked to original sources
PubMed2000

A sensitive procedure for the study of beta-carotene-d8 metabolism in humans using high performance liquid chromatography-mass spectrometry.

This report describes the development of a robust method of high sensitivity for studying the metabolism of beta-carotene-d8 in humans using a combination of liquid chromatography/particle beam-mass spectrometry (LC/PB-MS). The utility of the LC/PB-MS method was demonstrated in a pilot study. The carotenoids were extracted from plasma into hexane and separated by reverse phase high performance liquid chromatography (HPLC) using a C-18 column. The HPLC effluent was nebulized using helium and the solvent was removed under vacuum within the dual-stage particle beam interface. The de-solvated carotenoids were ionized in the negative-ion mode (electron capture) using methane chemical ionization and detected using selected ion monitoring. The limit of detection of the method was on the order of 0.3 ng (approximately 0.6 pmol) for beta-carotene. beta-Carotene-d8 was quantified in the plasma over a concentration range of two orders of magnitude using beta-carotene-(13)C(40) as an internal standard. The overall coefficient of variance (CV) for determining the concentration of the analytes from 30 microliter of plasma was 3.9% for beta-carotene and 2.4% for beta-carotene-d8. Using the LC/PB-MS method, the concentration of beta-carotene-d8 was determined in the plasma of a subject who had consumed a single 5-mg dose over a 30-day period. The sensitive semi-automated procedure is capable of high sample throughput and makes large comprehensive studies feasible.

Chromatography, High Pressure Liquid↗
PubMed1999

A chronic ethanol-feeding study in rhesus monkeys.

This study describes the effect of chronic ethanol-feeding in rhesus monkeys. Animals which were maintained on a diet containing 18:2n-6 and 18:3n-3 as 1.4 and 0.08% of the calories, respectively, and consumed alcohol (mean 2.6 g kg(-1) d(-1)) had decreased amounts of 20:4n-6 and 22:6n-3 in their livers and plasma lipids compared with controls. Alcohol consumption did not appear to effect the absorption of 2H(5)-18:2n-6 and 18:3n-3 esters into the blood following an oral dose. There was an increase in 2H5 enrichment in plasma 20:4n-6 and 22:6n-3, indicating that alcohol may have increased production of these fatty acids. There was a greater concentration of 4-hydroxynonenal in the plasma of alcohol-exposed monkeys compared to controls.

Alcoholism↗
PubMed1999

Alcohol consumption in rhesus monkeys depletes tissues of polyunsaturated fatty acids and alters essential fatty acid metabolism.

Rhesus monkeys that were maintained on an adequate diet but with low levels of essential fatty acids (1.4 en% linoleic, 18:2n-6, and 0.08 en%, linolenic acid, 18:3n-3) became depleted of 20:4n-6, and 22: 6n-3 in their livers, plasma lipoproteins, and erythrocytes during an 18-month period of alcohol exposure (2.6 g kg(-1) day(-1)). Monkeys that consumed alcohol also had higher plasma concentrations of 4-hydroxynonenal compared to controls. The metabolism of 18:2n-6 and 18:3n-3 were evaluated in both groups of animals using deuterium-labeled substrates over a 9-day period. Alcohol consumption did not appear to have an effect on the absorption of either 2H5-18:2n-6 or 2H5-18:3n-3 ethyl esters into the circulation after a single oral dose. However, there was a greater enrichment of deuterium in the biosynthesized fatty acids, 20:4n-6 and 22:6n-3, in the plasma of the monkeys exposed to alcohol compared to controls. These results suggest that chronic alcohol exposure may lead to a stimulation of the rate at which long-chain polyunsaturated fatty acids are biosynthesized to compensate for an increase in lipid peroxidation.

Aldehydes↗
PubMed1997

The effects of low dietary levels of polyunsaturates on alcohol-induced liver disease in rhesus monkeys.

Rhesus monkeys that were maintained on a diet containing low, yet adequate, amounts of vitamins C and E and in which linoleate and linolenate represented 1.4% and 0.08% of the total caloric intake, respectively, developed liver fibrosis after consuming alcohol (mean, 2.6 g kg(-1) d[-1]) over a period of 3 years. In the liver, several polyunsaturated fatty acids including 18:2n6, 20:4n6, and 22:6n3 decreased compared with dietary controls, and similar findings were also observed in plasma lipoproteins and erythrocytes. The amount of alcohol consumed correlated positively with plasma lipid peroxidation products, 4-hydroxynonenal (4-HNE) and 8-isoprostane F2alpha, and negatively with 20:4n6 and 22:6n3 levels. These findings imply that alcoholics who also have a marginal intake of essential fatty acids and antioxidants in their diets may be at an increased risk of developing liver disease.

Aldehydes↗
PubMed1997

Retinal and brain accretion of long-chain polyunsaturated fatty acids in developing felines: the effects of corn oil-based maternal diets.

A study was carried out in domestic felines to determine whether corn oil-based maternal diets are an adequate source of essential fatty acids to support normal accumulation of long-chain polyunsaturated fatty acids in the brains and retinas of offspring and whether these diets have any subsequent effect on visual function. Female domestic felines were acclimated to one of six different defined diets 1 mo before mating and maintained on the diets throughout pregnancy and lactation. Four diets contained only corn and hydrogenated coconut oils as their source of fat in ratios of 1:9, 3:7, 6:4, and 9:1, respectively. Two reference diets also contained the long-chain polyunsaturated fatty acids arachidonate (20:4n-6) and docosahexaenoate (22:6n-3). When the offspring were 8 wk old, electroretinograms were obtained and the a- and b-wave implicit times were determined. The results showed that animals raised in litters in which the maternal diets were devoid of 20:4n-6 and 22:6n-3 had an increase in a- and b-wave implicit times compared with the controls. In the rod outer segments and brains of these animals, there were lower amounts of 22:6n-3 and higher amounts of long-chain n-6 polyunsaturated fatty acids compared with control animals. These findings showed that although corn oil-based diets were capable of maintaining 20:4n-6 concentrations in the developing brain and retina, only those diets containing 22:6n-3 could support a high accumulation of docosahexaenoic acid in these tissues. Moreover, low amounts of 22:5n-6 in the brains of animals in all of the corn oil-diet groups suggested that young felines have a low biosynthetic capacity to produce this fatty acid or 22:6n-3. These findings suggest that in juvenile felines, maintenance of 22:6n-3 status in the nervous system is important for optimal retinal function.

Animals↗
PubMed1996

Essential fatty acid uptake and metabolism in the developing rodent brain.

Studies were carried out to determine whether the brain takes up and metabolizes essential fatty acids during early postnatal development in rodents. Rats and mice were dosed with deuterium-labeled linoleic and linolenic acids either by intraperitoneal injection or by gavage. Animals were killed at different times thereafter, and organs were removed. Brains, livers, and blood were analyzed by gas chromatography--negative-ion-mass spectrometry for labeled fatty acids. To determine whether fatty acids were present in the brain apart from cerebral blood, a subset of animals was exsanguinated by perfusion with buffered saline, and the brain was then fractionated into subcellular components. Results demonstrated that the brain took up both labeled essential fatty acids within 8 h from the time of dosing. There was on average a greater uptake of linolenic acid into the cerebellum than into the cerebral cortex during the first 8 d of life in rats. The amount of linoleic acid taken into either region was similar, however. Docosahexaenoic acid intermediates, 20:5n-3 and 22:5n-3, were also found labeled in the brain. Time-course labeling experiments indicated that these intermediates may be converted to 22:6n-3 within the brain. A rise of labeled 22:6n-3 in the brain at 24 h appeared to be due to uptake of this fatty acid from the blood. The amount of labeled 22:6n-3 in the brain continued to increase beyond 24 h, and this did not appear to be correlated with its blood concentration. These results suggest that, during development in the rodent, different regions within the brain may vary in their capacity to synthesize 22:6n-3, and this may be correlated with regional growth rates.

Administration, Oral↗
PubMed1996

Is dietary arachidonic acid necessary for feline reproduction?

A study was carried out to determine whether corn oil-based diets devoid of arachidonic acid, 20:4(n-6), are capable of supporting feline reproduction. One group of four adult female felines were acclimated to a 10 weight% (wt%) fat diet consisting of 1 wt% corn oil and 9 wt% hydrogenated coconut oil for 1 mo before mating. One female produced two live offspring, and the other three females delivered either stillborn fetuses or offspring that were severely deformed and died shortly after birth. Two of these females were subsequently placed on a 1 wt% corn oil diet that was supplemented with 20:4(n-6) (200 mg/ kg of diet), and after 2 mo they were mated. Offspring resulting from the second mating were healthy. A third group of females that were maintained on a 10 wt% fat diet consisting of 3 wt% corn oil were also mated. The offspring from these matings appeared healthy at birth. Neonates from each diet group were killed, and the fatty acyl composition of the livers, plasma and brains was analyzed. In the offspring livers and plasma, the level of 20:4(n-6) from both the 1 wt% or 3 wt% corn oil diet groups was about half that of offspring from those receiving 20:4(n-6) in the diet. There were no differences in the level of 20:4(n-6) in the neonate brains among any of the groups. This study suggests that nutritional factors unrelated to the tissue accumulation of arachidonic acid in the offspring may be responsible for the high percentage of stillbirths and deformities associated with maternal diets containing low amounts of essential fatty acids but that diets that contain a higher percentage of corn oil can support feline reproduction.

Animals↗
PubMed1995

Ethanol exposure causes a decrease in docosahexaenoic acid and an increase in docosapentaenoic acid in feline brains and retinas.

Alcohol altered the fatty acyl composition of the liver, brain, and retina of domestic felines that were maintained on a diet having low, but adequate, amounts of essential fatty acids. For 8 mo, seven adult cats were provided a diet with 10% fat (by wt), consisting of 9:1 ratio of hydrogenated coconut oil:corn oil. During 6 of these 8 mo, four of the cats were given oral daily doses of a 95% ethanol solution (1.2 g.kg-1.d-1). Cats were killed and the fatty acyl composition of tissues were determined. In the plasma and livers of the alcohol-exposed animals, there were significant decreases in the concentrations of 18:2 omega 6, 20:4 omega 6, 22:5 omega 3, and 22:6 omega 3 and increases in the concentrations of the nonessential fatty acids 16:1 omega 7, 18:1 omega 9, and 20:3 omega 9. In the brains and retinas of the alcohol-exposed animals, 22:6 omega 3 decreased by 17% and there was a compensatory increase in 22:5 omega 6. In the retinas, the concentration of 22:5 omega 6 increased by 250%. The reciprocal change in the ratio of 22:6 omega 3 to 22:5 omega 6 is known to be associated with a loss in nervous system function and may provide a biochemical mechanism underlying some of the neuropathology associated with alcoholism.

Animals↗
PubMed1992

High sensitivity negative ion GC-MS method for detection of desaturated and chain-elongated products of deuterated linoleic and linolenic acids.

A sensitive negative chemical ionization (NCI) gas chromatography-mass spectrometry (GC-MS) method for the detection of pentafluorobenzyl (PFB) esters of deuterated fatty acids is described. Deuterated linoleic [18:2n-6 2H4-9,10,12,13] and linolenic [18:3n-3 2H5-17,17,18,18,18] acids were converted to chain-elongated and desaturated products during incubations with homogenates prepared from rat liver. The extracted fatty acids were derivatized with pentafluorobenzyl bromide and analyzed in the negative ion mode by GC-MS. The detection limit of the PFB esters in NCI using selected ion monitoring was below 10 femtograms. In general, detection of the PFB derivatives using the negative ion mode was more than three orders of magnitude more sensitive than using a positive chemical ionization (PCI) method with methyl ester derivatives. The PFB esters of the 2H4-18:2n-6 metabolites eluted with their unlabeled analogues, whereas the PFB esters of the 2H5-18:3n-3 metabolites were resolved from the unlabeled compounds on polar capillary FFAP columns. Isotope ratios of the 2H4-18:2n-6 metabolites were used to quantify the deuterated compounds from standard dilution curves generated from the ion abundances of the unlabeled fatty acids. The 2H5-18:3n-3 metabolites were quantified similarly using 18:3n-3. This method is feasible for the study of the in vivo metabolism of deuterated essential fatty acids in whole animals.

Animals↗
PubMed1991

Mass spectral analysis and fragment ion structure of fusarochromanone.

Fusarochromanone is a mycotoxin produced by Fusarium equiseti that is implicated in the poultry disease tibial dyschrondroplasia. Electron impact ionization tandem mass spectrometry was used to elucidate probable structures of fragment ions found at m/z 274, 275, 261, 233, 218 and 191 and for devising an analytical rationale for the metabolites of the parent compound. In addition, a sensitive, qualitative liquid chromatographic technique using direct injection continuous-flow fast atom bombardment for the detection of fusarochromanone in corn was devised. Analysis was carried out on a hybrid tandem instrument (VG-7070EQ) using open tubular columns (75 microns i.d.) with direct-flow open-loop injection. The limit of detection of the pure compound was 500 pg in the selected ion monitoring mode. A 50 p.p.b. (500 pg injected) of the pure compound added to ground corn samples was the lowest detectable amount in a biological matrix.

Amino Acids↗
PubMed1990

Isoverrucarol production by Fusarium oxysporum CJS-12 isolated from corn.

Isoverrucarol (3,15-dihydroxy-12,13-epoxy-trichothec-9-ene) was isolated and purified from wheat cultures of a toxic strain of Fusarium oxysporum CJS-12. The toxin was characterized by thin-layer chromatography, gas chromatography-mass spectrometry, and 1H and 13C nuclear magnetic resonance spectrometry. Isoverrucarol caused toxic effects in rats, including loss of appetite, bodily weakness, severe mucosae of the stomach, and death, when administered orally at 10 and 20 mg/kg of body weight. The toxin also caused a definite dermatitic reaction of epidermis and an edematic-necrotic response of the dermis.

Animals↗
PubMed1989

Biosynthesis of fusarochromanone and its monoacetyl derivative by Fusarium equiseti.

One fluorescent compound previously named TDP-2 was isolated and purified from a rice culture of Fusarium equiseti (Alaska 2-2). Mass spectral and nuclear magnetic resonance data indicated that it is a C-3'-N-acetyl derivative of fusarochromanone, a newly discovered mycotoxin. Time course studies of synthesis of these two compounds on autoclaved rice and Czapek-Dox medium enriched with soybean peptone indicated that fusarochromanone was converted to TDP-2 in the cultures. A high concentration of peptone in the liquid medium may stimulate both fusarochromanone synthesis and its conversion to TDP-2.

Amino Acids↗
PubMed1985

Effect of cleaning, milling, and baking on deoxynivalenol in wheat.

Samples of wheat naturally infected by Fusarium graminearum Schwabe were obtained from mills in Oklahoma, Missouri, Kansas, and Minnesota and fields in Nebraska and Kansas in 1982; they were analyzed for deoxynivalenol (DON). The wheat was milled, and DON was found throughout all the milling fractions (bran, shorts, reduction flour, and break flour). The DON recoveries for each mill run ranged from 90 to 98%. These samples, regardless of DON concentration, also gave similar fractional distributions of DON. The greatest (21 ppm [21 micrograms/g]) concentration of DON was found in the bran, and the smallest (1 ppm) was found in the break flour. Cleaning and milling were not effective in removing DON; DON was not destroyed in the bread baked from the naturally contaminated whole wheat flour, but the effect on its concentration in the samples analyzed varied, the reduction ranging from 19 to 69%. The percent reduction found in the cleaned wheat ranged from 6 to 19%. DON concentrations in the following commercially made breads, caraway rye, seedless rye, and pumpernickel, were 45 ppb (ng/g), 39 ppb, and 0 ppb, respectively. The limits of detection by gas chromatography-mass spectrometry and high-pressure liquid chromatography for DON were 0.5 and 10 ng, respectively.

Food Contamination↗