Red blood cell fatty acid ethyl esters: a significant component of fatty acid ethyl esters in the blood

Flaxseed oil modulates testicular biometrics, hormone, libido, antioxidant and semen profiles in endangered Teressa goat of Andaman and Nicobar Islands

Teressa goat is a unique goat breed in Andaman and Nicobar Islands (ANI) of India. Effects of Flaxseed oil (FSO) supplementation in body weight (BW), scrotal circumference (SC), testicular volume (TV) and testicular weight (TW), endocrinological profiles, sex behavioural profiles (SBPs), oxidative stress markers and semen production and its quality profiles in rainy and dry summer season were studied in Teressa goat. Male goats (n = 12) of 3-4 years old were equally divided into control and treated groups. Treated animals received 25 mL FSO per day. Oral drenching of FSO was done in the morning before feeding the concentrate ration. Body weight, scrotal circumference, TV and TW were measured in bucks of FSO treated and untreated during rainy and dry summer seasons. Blood follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone, thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), cortisol and prolactin, total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA) were measured in bucks of FSO treated and untreated during rainy and dry summer seasons. Libido score (LS), mating ability score (MAS) and sex behavioural score (SBS) were estimated at time of semen collection in bucks of FSO treated and untreated during rainy and dry summer seasons. Semen samples (n = 100; 50 semen samples from each season; each 25 semen samples from control and treatment groups per season) were collected and analysed for semen quality profiles. One-way ANOVA (control rainy, control dry, treated rainy and treated dry) revealed that BW, SC, TV and TW, FSH, LH, testosterone, TSH, T3 and T4 were higher (P < 0.05) and cortisol and prolactin were lower (P < 0.05) in FSO treated bucks of rainy season followed by untreated bucks of rainy season, FSO treated bucks of dry summer season and were lower (P < 0.05) in untreated bucks of dry summer season. Similarly, TAC, CAT, SOD and GSH, LS, MAS and SBS, and volume, pH, sperm concentration, mass activity, total motility (TM), viability, acrosomal integrity (AcI), plasma membrane integrity (PMI) and nuclear integrity (NI) were higher (P < 0.05) and MDA and TSA were lower (P < 0.05) in FSO treated bucks of rainy season followed by FSO treated bucks of dry summer season, untreated bucks of rainy season and were lower (P < 0.05) in untreated bucks of dry summer season. The results of the present study indicated that the breeding bucks suffered physiological stress (higher cortisol), oxidative stress (higher MDA and deficiency of antioxidants), hormonal imbalance (higher prolactin and cortisol and deficiency of gonadotropins, gonadal hormone and thyroid hormones) and infertility due to poor libido and poor semen production and its quality profiles during dry summer season. Thus, dry summer was more stressful season compared to rainy season for the goat bucks. FSO supplementation mitigated these stresses and improved the scrotal and testicular biometrics, libido, antioxidants, hormones and semen quality profiles in Teressa goat bucks. The current study concluded that FSO effectively improved the hormones, libido, antioxidant profiles, and scrotal and testicular biometrics with cascading beneficial effects on semen quality profiles in Teressa goat bucks under humid tropical island ecosystem of Andaman and Nicobar Islands.

Effect of isotretinoin (Netlook) on the testis of adult male albino rats and the role of omega 3 supplementation: A histological and biochemical study

Isotretinoin is an oral retinoid which used across the world in the treatment of patients especially adolescents complaining of acne. In spite of the prevalent clinical use of isotretinoin, the generation of oxidative stress with the affection of several organs leads to the limitation and restriction of its use. Omega-3 (N-3) is an essential polyunsaturated fatty acid (PUFAs) with powerful antioxidant properties. The aim of this study was to investigate the histological and biochemical changes occurring in the rat testis following isotretinoin intake and to evaluate the role of omega 3 supplementation in ameliorating testicular damage. Thirty adult male albino rats were divided equally into three groups. Group I is the control group, group II received isotretinoin (1.0 mg/kg/day) dissolved in distilled water and group III received isotretinoin (1.0 mg/kg/day) and omega 3 (400 mg/kg/day). Testis samples were collected and processed for light and electron microscopic examination. The blood samples were collected for biochemical assessments. Results indicated that isotretinoin caused histological changes in all stages of spermatogenesis and alterations of the hormonal assay. These changes in the rat testis which were corrected by omega 3 use.

Age-related and atherosclerosis-related erythropathy in ApoE/LDLR-/- mice

In this work we applied a multimodal approach to define the age- and atherosclerosis-related biochemical and functional alterations in red blood cells (RBCs) in ApoE/LDLR^-/- mice. Our results revealed that age-related changes in RBCs, such as decreases in RBC deformability and mean height, were more pronounced in ApoE/LDLR^-/- mice than in age-matched control mice (C57BL/6J). The decreases in phospholipid content and level of lipid unsaturation were accompanied by an increase in cholesterol esters and esterified lipids in RBC membranes in aged C57BL/6J mice. The age-related decrease in the phospholipid content was more pronounced in ApoE/LDLR^-/- mice. In contrast, the increase in the total lipid content in RBC membranes occurred only in ApoE/LDLR^-/- mice with advanced atherosclerosis. The age-related alterations also included a decrease in the ratio of turns to α-helices in the secondary structure of hemoglobin (Hb) inside intact RBCs. On the other hand, an increase in the ratio of unordered conformations to α-helices of Hb was observed only in ApoE/LDLR^-/- mice and occurred already at the age of 5-weeks. This was related to hypercholesterolemia and resulted in an increased oxygen-carrying capacity. In conclusion, progressive mechanical and functional alterations of RBCs in aged ApoE/LDLR^-/- mice were more pronounced than in age-matched C57BL/6J mice. Although, several biochemical changes in RBCs in aged ApoE/LDLR^-/- mice recapitulated age-dependent changes observed in control mice, some biochemical features of RBC membranes attributed to hypercholesterolemia were distinct and could contribute to the accelerated deterioration of RBC function in ApoE/LDLR^-/- mice.

Flaxseed oil modulates semen production and its quality profiles, freezability, testicular biometrics and endocrinological profiles in mithun

Mithun (Bos frontalis) is a unique domestic free range bovine species of North Eastern Hilly (NEH) regions of India. Effect of feed supplementation of Flaxseed oil (FSO) on semen production and its quality profiles, freezability, oxidative stress, apoptotic sperm percentage and subsequently on endocrinological profiles & scrotal and testicular biometrics in different seasons was studied in mithun. The experimental animals were divided into two groups, Gr I: Control (n = 3) and Gr II: Treatment (n = 3; Flaxseed oil @ 150 mL/day). FSO was supplemented through oral drench in the morning hours just before concentrate feeding. A total of 80 semen samples (n = 80; 20 semen samples from each season; each 10 semen samples from control and treatment groups per season) were collected, not more than twice per week in winter, spring, autumn and summer seasons. Semen quality profiles (SQPs) such as volume, sperm concentration, motility (forward progressive and total), motility & velocity profiles by computer assisted sperm analyser (CASA), viability, total sperm abnormality, acrosome integrity, plasma membrane & nuclear abnormality and apoptotic sperm percentage were estimated in fresh semen. Along with SQPs measured in fresh semen, motility in estrus bovine cervical mucus (bovine cervical mucus penetration test; BCMPT) and mitochondrial membrane potential (MMP) by JC-1 stain were determined in the post-thawed semen samples. Biochemical profiles (aspartate aminotransferase; AST, alanine aminotransferase; ALT, total cholesterol; CHO), antioxidant profiles (superoxide dismutase; SOD, catalase; CAT, glutathione; GSH, total antioxidant capacity; TAC) and oxidative stress profile (malondialdehyde; MDA) were estimated in fresh semen whereas AST, ALT, lactate dehydrogenase (LDH), TAC and MDA were estimated in the frozen thawed semen samples. Endocrinological profiles such as follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone, cortisol and thyroxin and scrotal circumference (SC) & testicular biometrics were measured in both groups in different seasons. Result revealed a significant (p < 0.05) improvement in motility (total & forward progressive, motility & velocity by CASA and vanguard distance in cervical mucus), viability, intactness of acrosome & plasma membrane, MMP, antioxidant profiles and reduction in total sperm and nuclear abnormalities, reduction in leakage of intracellular enzymes and reduction in oxidative stress profile and reduction of apoptotic sperm percentage were observed in FSO supplemented than in un-supplemented control group accordingly in fresh and post thawed semen samples. Blood FSH, LH, testosterone and thyroxin concentration were significantly (p < 0.05) increased and cortisol concentration was significantly (p < 0.05) decreased in FSO supplemented group than in unsupplemented control group. Similarly, SC and testicular biometrics were increased significantly (p < 0.05) in supplemented than unsupplemented group for different seasons and significantly (p < 0.05) higher in winter and spring than in summer season in the experimental groups. It can be concluded from the study that supplementation of FSO can effectively be utilized to improve the antioxidant profiles, reduction of oxidative stress with cascading beneficial effects on SQPs and fertility status of the mithun bull.

Attenuation of arsenic trioxide induced cardiotoxicity through flaxseed oil in experimental rats

OBJECTIVES

Arsenic trioxide (As₂O₃) is a potent drug for acute promyelocytic leukaemia, but its clinical trials are allied with some serious adverse events mainly cardiac functional abnormalities. So the objective of our investigation is to identify the cardioprotective action of flaxseed oil (FSO), a natural compound against As₂O₃ induced cardiotoxicity.

METHODS

Male wistar rats were treated with As₂O₃ (4 mg/kg) to induce cardiotoxicity. FSO (250 and 500 mg/kg) was given in combination with As₂O₃ for evaluating its cardioprotective efficacy.

RESULTS

Treatment with As₂O₃ resulted in deposition of arsenic in heart tissue, increased cardiac marker enzymes release, lipid peroxidation (LPO), oxidative insults and pathological damages in the heart. Co-treatment with FSO (500 mg/kg) significantly reduced the arsenic accumulation, cardiac marker enzymes, LPO and cardiac structural alterations. FSO treatment significantly improved cardiac glutathione content, antioxidant enzymes and reduced the pathological damages in cardiac tissue. Gas chromatographic-mass spectrometry analysis revealed that the major fatty acid content in the FSO is alpha-linolenic acid, which has a strong milieu in cardiac health.

CONCLUSION

The results of the current investigation suggested that FSO is an effective agent in reducing arsenic-induced cardiac toxicity and can be used as an adjunct/dietary supplement for the cancer patients on As₂O₃ therapy.

Bioequivalence Demonstration for Ω-3 Acid Ethyl Ester Formulations: Rationale for Modification of Current Guidance

The US Food and Drug Administration (FDA) draft guidance for establishing bioequivalence (BE) of ω-3 acid ethyl esters (containing both eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA] as ethyl esters), used to treat severe hypertriglyceridemia, recommends the conduct of 2 studies: one with participants in the fasting state and one with participants in the fed state. For the fasting study, the primary measures of BE are baseline-adjusted EPA and DHA levels in total plasma lipids. For the fed study, the primary measures of BE are EPA and DHA ethyl esters in plasma. This guidance differs from that established for icosapent ethyl (EPA ethyl esters) in which the primary measure of BE is baseline-adjusted total EPA in plasma lipids for both the fasting and fed states. The FDA guidance for ω-3 acid ethyl esters is not supported by their physiologic characteristics and triglyceride-lowering mechanisms because EPA and DHA ethyl esters are best characterized as pro-drugs. This article presents an argument for amending the FDA draft guidance for ω-3 acid ethyl esters to use baseline-adjusted EPA and DHA in total plasma lipids as the primary measures of BE for both fasting and fed conditions. This change would harmonize the approaches for demonstration of BE for ω-3 acid ethyl esters and icosapent ethyl (EPA ethyl esters) products for future development programs and is the most physiologically rational approach to BE testing.

Synthesis of fatty acid ethyl esters in mammalian tissues after ethanol exposure: a systematic review of the literature

The ability to undergo non-oxidative metabolism from ethanol to fatty acid ethyl esters (FAEEs) varies greatly among tissues and organs. To gain a greater understanding of non-oxidative ethanol metabolism to FAEE, we aimed to collect all published data on FAEE synthesis in mammalian organs and tissues to identify all tissues, organs, and enzymes that are known to, or likely possess FAEE-synthetic activity. A systematic search for relevant papers was performed and two independent reviewers examined potentially relevant abstracts (articles on FAEEs that pertain to ethanol exposure) to determine whether they met the inclusion criteria. Information on FAEE synthesis was retrieved from papers meeting the inclusion/exclusion criteria and summarized by organ/tissue/matrix examined. The systematic search through four databases yielded 78 articles that investigated FAEE synthesis by tissues, tissue fractions and cell lines, and 29 articles that attempted to purify and/or characterize the enzymes involved in FAEE synthesis. Two enzyme activities have been studied: FAEE synthase (FAEES, which conjugates ethanol and free fatty acid) and acyl-CoA: ethanol O-acyltransferase (AEAT, which conjugates ethanol and fatty acyl-CoA). Both activities are expressed by a variety of different enzymes. FAEES activity is the most widely studied and has been purified from several tissues and shown to be associated with several well-known enzymes, while the identity of enzymes possessing AEAT activity remains unknown. The organs and tissues that have been shown to synthesize FAEEs are discussed, with special emphasis on the studies that attempted to elucidate the enzymology of FAEE synthesis in those tissues.

The influence of nanodiamond on the oxygenation states and micro rheological properties of human red blood cells in vitro

Nanodiamond has been proven to be biocompatible and proposed for various biomedical applications. Recently, nanometer-sized diamonds have been demonstrated as an effective Raman/fluorescence probe for bio-labeling, as well as, for drug delivery. Bio-labeling/drug delivery can be extended to the human blood system, provided one understands the interaction between nanodiamonds and the blood system. Here, the interaction of nanodiamonds (5 and 100 nm) with human red blood cells (RBC) in vitro is discussed. Measurements have been facilitated using Raman spectroscopy, laser scanning fluorescence spectroscopy, and laser diffractometry (ektacytometry). Data on cell viability and hemolytic analysis are also presented. Results indicate that the nanodiamonds in the studied condition do not cause hemolysis, and the cell viability is not affected. Importantly, the oxygenation/deoxygenation process was not found to be altered when nanodiamonds interacted with the RBC. However, the nanodiamond can affect some RBC properties such as deformability and aggregation in a concentration dependent manner. These results suggest that the nanodiamond can be used as an effective bio-labeling and drug delivery tool in ambient conditions, without complicating the blood's physiological conditions. However, controlling the blood properties including deformability of RBCs and rheological properties of blood is necessary during treatment.

Effects of flaxseed oil on anti-oxidative system and membrane deformation of human peripheral blood erythrocytes in high glucose level

BACKGROUND

The erythrocyte membrane lesion is a serious diabetic complication. A number of studies suggested that n-3 fatty acid could reduce lipid peroxidation and elevate α- or γ-tocopherol contents in membrane of erythrocytes. However, evidence regarding the protective effects of flaxseed oil, a natural product rich in n-3 fatty acid, on lipid peroxidation, antioxidative capacity and membrane deformation of erythrocytes exposed to high glucose is limited.

METHODS

Human peripheral blood erythrocytes were isolated and treated with 50 mM glucose to mimic hyperglycemia in the absence or presence of three different doses of flaxseed oil (50, 100 or 200 μM) in the culture medium for 24 h. The malondialdehyde (MDA) and L-glutathione (GSH) were measured by HPLC and LC/MS respectively. The phospholipids symmetry and membrane fatty acid composition of human erythrocytes were detected by flow cytometry and gas chromatograph (GC). The morphology of human erythrocyte was illuminated by ultra scanning electron microscopy.

RESULTS

Flaxseed oil attenuated hyperglycemia-induced increase of MDA and decrease of GSH in human erythrocytes. Human erythrocytes treated with flaxseed oil contained higher C22:5 and C22:6 than those in the 50 mM glucose control group, indicating that flaxseed oil could reduce lipid asymmetric distribution and membrane perturbation. The ultra scanning electron microscopy and flow cytometer have also indicated that flaxseed oil could protect the membrane of human erythrocytes from deformation at high glucose level.

CONCLUSION

The flaxseed oil supplementation may prevent lipid peroxidation and membrane dysfunction of human erythrocytes in hyperglycemia.

Adaptive changes in fatty acid profile of erythrocyte membrane in relation to plasma and red cell metabolic changes in chronic alcoholic men

Chronic alcohol consumption is a major reason for several human diseases, and alcoholism has been associated with a variety of societal problems. Changes in fatty acid metabolism in alcoholics and its effects leading to membrane damage are largely unknown. Therefore, we aimed to investigate the fatty acid composition of erythrocyte membrane phospholipids in relation with plasma lipid profile and other plasma metabolites in chronic alcoholics in comparison with controls. We systematically measured the levels of glucose, lactate and pyruvate in the blood and free amino acids, free fatty acids, mucoproteins and glycolipids, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein (VLDL) cholesterol and triglycerides (TG) in plasma of chronic alcoholics and controls. Furthermore, we measured fatty acid composition by gas chromatographic analysis. The fatty acid composition clearly revealed certain changes in chronic alcoholic erythrocyte membrane, chiefly increments in C16:0 and a decrease in C22:4 and C22:6 fatty acids besides the presence of unidentified fatty acids, probably C-24 or C-26 fatty acids. In addition, a significant increase in blood lactate, decrease in blood pyruvate and increased levels of free amino acids and free fatty acids, mucoproteins, VLDL cholesterol, TG and HDL-C in chronic alcoholics were observed with no significant change in plasma TC, LDL-C and glycolipids when compared with controls. Alcohol-induced alterations in plasma and erythrocyte membranes of chronic alcoholics in the present study might be an adaptive response to counteract the deleterious effects of alcohol. The implications of our findings warrant further investigation and needs further in-depth study to explore the mechanisms of alcohol-induced membrane changes.

In Heavy Drinkers, Fatty Acid Ethyl Esters Remain Elevated for Up to 99 Hours

BACKGROUND

Both medical and forensic needs require reliable detection of earlier ethanol intake after the disappearance of ethanol from blood. The esters of ethanol with free fatty acids (FAEEs) are candidate markers of this kind. However, it is unknown whether FAEEs can serve as a marker for a single prior ethanol intake. In addition, the period for which FAEEs are elevated is unknown. Therefore, we measured FAEEs in heavy drinkers admitted to detoxification, and in healthy subjects after a drinking experiment.

METHODS

Blood from 30 heavy drinkers was obtained for up to 5 days during a detoxification period in a psychiatric hospital. In addition, 17 healthy subjects who participated in a drinking experiment and who were abstinent thereafter gave blood during a similar time period for analysis of FAEEs. Fatty acid ethyl esters were measured by gas chromatography-mass spectroscopy.

RESULTS

Heavy drinkers had much higher ethanol and FAEEs concentrations than healthy subjects; however, in both groups, FAEEs decreased rapidly during the first day. Only in heavy drinkers, elevated concentrations of FAEEs were observed at days 2 to 4. Concentrations of FAEEs were not associated with serum triglycerides or patients' body mass index.

CONCLUSIONS

It is concluded that kinetics of FAEEs are different in heavy drinkers compared with healthy subjects and that FAEEs are of limited value for the detection of prior single ethanol intake.

Optical measurement of cell membrane tension

Using a novel noncontact technique based on optical interferometry, we quantify the nanoscale thermal fluctuations of red blood cells (RBCs) and giant unilamellar vesicles (GUVs). The measurements reveal a nonvanishing tension coefficient for RBCs, which increases as cells transition from a discocytic shape to a spherical shape. The tension coefficient measured for GUVs is, however, a factor of 4-24 smaller. By contrast, the bending moduli for cells and vesicles have similar values. This is consistent with the cytoskeleton confinement model, in which the cytoskeleton inhibits membrane fluctuations [Gov et al., Phys. Rev. Lett. 90, 228101, (2003).

Ethanol administration to cystic fibrosis knockout mice results in increased fatty acid ethyl ester production

BACKGROUND

Fatty acid ethyl esters (FAEE) are nonoxidative ethanol metabolites shown to produce toxic effects in the liver and pancreas in vivo and in vitro. Because alcohol-induced chronic pancreatitis is associated with mutations in the gene responsible for cystic fibrosis (CFTR), we hypothesized that CFTR dysfunction leads to increased levels of these toxic nonoxidative ethanol metabolites following alcohol administration.

METHODS

Cystic fibrosis (CF) and wild-type (WT) mice were injected intraperitoneally with 1, 2, or 3 g/kg of 50% ethanol. Mice were sacrificed and the liver and pancreas removed for FAEE analysis.

RESULTS

The mean FAEE concentration (pmol/g) detected in the liver of cftr mice following injection with 2 g/kg of ethanol was significantly greater than the amount detected in WT (p < 0.005). A similar trend in FAEE concentration was seen in the pancreas, but the difference was not statistically different. In both the liver and pancreas, analysis of individual FAEE species demonstrated a selective increase in ethyl oleate.

CONCLUSION

These data show an association between CFTR dysfunction and qualitative and quantitative changes in FAEE in liver and pancreas upon ethanol exposure.

Fatty acid ethyl esters in meconium: are they biomarkers of fetal alcohol exposure and effect?

BACKGROUND

Biomarkers of fetal exposure to alcohol are important to establish so that early detection and intervention can be made on these infants to prevent undesirable outcomes. The aim of this study was to analyze long-chain fatty acid ethyl esters (FAEEs) in meconium as potential biomarkers of fetal alcohol exposure and effect.

METHODS

Fatty acid ethyl esters were analyzed in the meconium of 124 singleton infants by positive chemical ionization gas chromatography/mass spectrometry (GC/MS) and correlated to maternal ethanol use.

RESULTS

A total of 124 mother/infant dyads were enrolled in the study: 31 were in the control group and 93 were in the alcohol-exposed group. The incidence (28% vs 9.7%, p = 0.037) of ethyl linoleate detected in meconium was significantly higher in the alcohol-exposed groups than the control groups. Similarly, when the concentrations of ethyl linoleate in meconium were grouped (trichotomized), there was a significant linear by linear association between alcohol exposure and group concentrations of ethyl linoleate (p = 0.013). Furthermore, only alcohol-exposed infants were found in the group with the highest ethyl linoleate concentration. The sensitivity of ethyl linoleate in detecting prenatal alcohol exposure was only 26.9%, and its specificity and positive predictive value were 96.8 and 96.2%, respectively. There was no significant correlation between the concentration of ethyl linoleate in meconium and absolute alcohol consumed (oz) per drinking day across pregnancy, although a trend toward a positive correlation is seen at lower amounts of alcohol consumed. Among the polyunsaturated, long-chain FAEEs, there was weak evidence that the incidence (21.5% vs 6.5%, p = 0.057) and concentration (p = 0.064) of ethyl arachidonate (AA) were significantly higher in the alcohol-exposed groups than the control groups. Ethyl linolenate and ethyl docosahexanoate (DHA) in meconium were found only in the alcohol group, although not at statistically significant levels. Highly significant correlations were found among the concentrations of ethyl linoleate, ethyl linolenate, ethyl AA, and ethyl DHA in meconium (correlations ranged between rs = 0.203, p = 0.024; and rs = 0.594, p < 0.001).

CONCLUSION

We conclude that FAEEs in meconium, particularly ethyl linoleate and ethyl AA, are biomarkers of high specificity for prenatal exposure to alcohol in newborn infants. We also propose that ethyl AA and DHA could be potential biomarkers of fetal alcohol effects on the developing fetal brain and should be investigated further.

Increased Plasma Fatty Acid Ethyl Ester Levels Following Inhibition of Oxidative Metabolism of Ethanol by 4-Methylpyrazole Treatment in Human Subjects

BACKGROUND

Recent experimental evidence suggests that fatty acid ethyl esters (FAEE), nonoxidative metabolites of ethanol, mediate ethanol-induced organ damage. A direct association between pancreas-specific toxicity and increased levels of FAEE following inhibition of the oxidative metabolism of ethanol by 4-methylpyrazole (4-MP) has previously been shown in studies with rats.

METHODS

We obtained plasma samples from 32 healthy human volunteers who drank ethanol following 4-MP or placebo ingestion to determine whether in vivo inhibition of oxidative metabolism of ethanol causes a shift to nonoxidative metabolism of ethanol and the subsequent production of increased levels of FAEE. Plasma FAEE were isolated by solid-phase extraction and quantified by gas chromatography-mass spectrometry (GC-MS).

RESULTS

Plasma FAEE levels in subjects receiving 4-MP treatment before ethanol consumption were elevated compared with plasma FAEE concentrations taken from control subjects who received a placebo before ethanol ingestion. Increased FAEE levels in the 4-MP treatment group occurred after peak blood ethanol, and peak FAEE levels were achieved. There was a correlation between the blood ethanol and the plasma FAEE levels, and the correlation persisted in the presence or absence of 4-MP. The peak FAEE values were greater in men than in women, with or without 4-MP treatment.

CONCLUSIONS

Our results indicate that the in vivo inhibition of the oxidative metabolism of ethanol using 4-MP results in an increased circulating concentration of FAEE, products of the nonoxidative metabolism of ethanol.

METHOD TO ASSESS FATTY ACID ETHYL ESTER BINDING TO ALBUMIN

AIMS

To develop a method to assess the relative binding of fatty acid ethyl esters (FAEE) and free fatty acids (FFA) to albumin, and to determine if binding affinity is related to fatty acid chain length and or degree of saturation.

METHODS

Radiolabelled ethyl-[14C] oleate bound to albumin was challenged with various ratios of FFA to FAEE. The displacement of ethyl-[14C] oleate by FFA was visualized and quantitated through a combination of native-PAGE, autoradiography, and liquid scintillation counting (LSC).

RESULTS

As the ratio of FFA to FAEE increased from 0:1 to 12:1, for all fatty acids tested (myristate, palmitate, stearate, oleate, linoleate, and arachidonate), ethyl-[14C] oleate displacement increased, when expressed as radioactivity (in DPM) as a percentage of control. In contrast, ethyl oleate did not displace stearate or oleate from albumin at molar ratios up to 5:1 (FAEE:FFA).

CONCLUSIONS

The method developed gave reproducible visualization of noncovalent binding of radiolabelled FAEE to albumin. The combination of native-PAGE and autoradiography LSC works well in assessing the binding properties of albumin and radiolabelled FAEE. The data indicate preferential binding of FFA over FAEE to albumin with six different FFA displacing FAEE to an approximately equal extent.

Fatty Acid Ethyl Esters in Human Mononuclear Cells: Production by Endogenous Synthesis Greatly Exceeds the Uptake of Preformed Ethyl Esters

BACKGROUND

Fatty acid ethyl esters (FAEE) are nonoxidative metabolites of ethanol. They are esterification products of ethanol and fatty acids. Fatty acid ethyl esters have been implicated as important mediators of ethanol-induced cytotoxicity, organ damage, and disease. In addition, they serve as specific and sensitive biomarkers for ethanol intake. Following ethanol consumption, FAEE are found in circulating blood bound to albumin or/and lipoproteins.

OBJECTIVES

Using a mononuclear fraction of white blood cells (WBC) exposed to ethanol, we investigated FAEE synthesis. We then determined the amount of uptake of preformed FAEE presented to the cells and compared the amounts of FAEE within the cells that were derived from endogenous synthesis with the amount derived from uptake of exposure FAEE. We also measured the persistence of FAEE within these cells and assessed the fate of the FAEE-associated fatty acid upon FAEE hydrolysis.

METHODS

A mononuclear fraction of human WBC was incubated with 25, 50, or 100 mM ethanol for 0.08 to 120 minutes, and FAEE synthesis was measured by gas chromatography/mass spectrometry. In other experiments, mononuclear cells were incubated with 25, 50, and/or 100 microM [3H]ethyl oleate, a representative FAEE species, for 0.08-120 minutes, and FAEE uptake and hydrolysis were measured.

RESULTS

The total FAEE formed by treating the cells with 25 mM ethanol, which represents a physiologic dose achievable with excess alcohol intake, greatly exceeded the FAEE within cells derived from uptake of 100 microM ethyl oleate, which represents a supraphysiologic dose. There was hydrolysis of FAEE by human mononuclear cells, with free fatty acids as major metabolites of FAEE hydrolysis. Unlike any other cell type or homogenate studied, the only ethyl ester formed by human mononuclear cells exposed to ethanol was ethyl oleate.

CONCLUSIONS

There is significant synthesis of FAEE by human mononuclear cells within seconds of exposure to physiologic doses of ethanol. The amount of FAEE in these cells derived from endogenous synthesis greatly exceeds the amount acquired by exogenous uptake.

Rapid, accurate, and sensitive fatty acid ethyl ester determination by gas chromatography-mass spectrometry

BACKGROUND

Fatty acid ethyl esters (FAEEs) are useful markers of ongoing alcohol use and may be associated with alcohol-induced damage to the liver and pancreas. In this article, we describe a novel method for rapid determination of the three major FAEEs found in human plasma.

METHODS

Internal standard, ethyl heptadecanoate, was added to plasma samples, and FAEEs were isolated by acetone precipitation, hexane lipid extraction, and amino-propyl silica solid phase extraction. FAEEs were quantitated by gas chromatography-mass spectrometry (GC-MS) using a nonpolar dimethylpolysiloxane column. The accuracy, precision, specificity, and sensitivity of the assay were defined from plasma samples from recently drinking and abstinent persons, with and without the addition of FAEEs.

RESULTS

Individual FAEE peaks demonstrated excellent resolution. Instrument time was reduced by more than 60%. The lower limit of detection was 5 to 10 nM, and the lower limit of quantitation for each FAEE was 60 nM (for 22 samples with known concentration 60 nM, x +/-SD: 61 +/- 5.7, 57 +/- 5.7, and 57 +/- 5.9 nM, for ethyl palmitate, ethyl oleate, and ethyl stearate, respectively). Instrument precision (coefficient of variance, CV) for these three FAEEs was 0.3%, 0.4%, and 0.7%, respectively. Intra-assay precision (CV) for total FAEEs was less than 7%. FAEEs were absent in 49 samples from abstinent persons. FAEEs were detected in all 76 samples with associated positive blood alcohol levels.

CONCLUSIONS

Our method of FAEE analysis is rapid and potentially useful in research and clinical studies. FAEE determination using this method is precise, accurate, sensitive, and specific and deserves broader application.

Detection of Recent Ethanol Intake With New Markers: Comparison of Fatty Acid Ethyl Esters in Serum and of Ethyl Glucuronide and the Ratio of 5-Hydroxytryptophol to 5-Hydroxyindole Acetic Acid in Urine

BACKGROUND

At present, recent ethanol consumption can be routinely detected with certainty only by direct measurement of ethanol concentration in blood or urine. Because ethanol is rapidly eliminated from the circulation, however, the time span for this detection is in the range of hours. Several new markers have been proposed to extend the detection interval, but their characteristics have not yet justified their use in routine clinical practice. We therefore investigated three new markers and compared their kinetics and sensitivities: (1) fatty acid ethyl esters (FAEEs) in serum, (2) ethyl glucuronide (EtG) in urine, and (3) the ratio of 5-hydroxytryptophol to 5-hydroxyindole acetic acid (5-HTOL/5-HIAA) in urine.

METHODS

Seventeen healthy men participated in a drinking experiment. Blood and urine samples were collected twice daily on three consecutive days and once daily on days 4 and 5. Ethanol concentration was determined by gas chromatography, FAEE levels, by gas chromatography with mass spectrometry, EtG concentration, by liquid chromatography-tandem mass spectrometry, and 5-HTOL/5-HIAA ratio, by high-performance liquid chromatography.

RESULTS

The peak serum ethanol concentrations of the subjects ranged from 5.4 to 44.7 mmol/liter (mean +/- SD, 30.1 +/- 9.1 mmol/liter). In the case of the serum ethanol determination, 100% sensitivity was reached only immediately after the end of the drinking experiment, and in the case of FAEE levels and 5-HTOL/5-HIAA ratio, it tested for 6.7 hr after the end of the ethanol intake. Thereafter, these latter parameters declined until 15.3 hr (FAEEs) and 29.4 hr (5-HTOL/5-HIAA), subsequently remaining in a stable range until 78.5 hr without further decrease. In contrast, EtG concentration showed 100% sensitivity until 39.3 hr and thereafter decreased, falling to below the limit of quantification of 0.1 mg/liter at 102.5 hr.

CONCLUSION

After moderate drinking, EtG in the urine proved to be a superior marker of recent ethanol consumption in healthy subjects. This is because EtG is a direct ethanol metabolite, it occurs in the urine only when ethanol has been consumed, and its sensitivity remains at the level of 100% for 39.3 hr.

COMPARISON OF SERUM FATTY ACID ETHYL ESTERS AND URINARY 5-HYDROXYTRYPTOPHOL AS BIOCHEMICAL MARKERS OF RECENT ETHANOL CONSUMPTION

AIMS

To examine the effects of an acute dose of ethanol on serum fatty acid ethyl esters (FAEEs) concentration and urinary 5-hydroxytryptophol (5-HTOL)/5-hydroxyindole-3-acetic acid (5-HIAA) ratio.

METHODS

Sixteen (14 male, 2 female) heavy alcohol drinkers were tested in a single, 2-day long session. Six participants received 1.5 g/l of ethanol/l of body water (approximately 0.75 g/kg of body weight, low dose group: LD) and 10 participants received 2.0 g/l of ethanol ( approximately 1.0 g/kg of body weight, high dose group: HD) in four divided doses every 20 min. Blood, urine, and breath samples were collected repeatedly over 36 h following the ingestion of ethanol and were analyzed for the presence of FAEE, 5-HTOL/5-HIAA, and ethanol, respectively. Serum gamma-glutamyltransferase (GGT), a marker of chronic ethanol use, was also included.

RESULTS

The breath ethanol level peaked approximately 1 h after the last dose, at 95 and 120 mg/dl for the LD and HD groups, respectively. The mean ratio of urinary 5-HTOL/5-HIAA was significantly elevated 5 and 9 h after ethanol administration, but returned to baseline 13 h after ethanol administration. This ratio was twice as high for the HD group compared with the LD group. Serum levels of FAEEs were significantly elevated at 5 h, but not 13 h after ethanol administration. There were no time-dependent changes in serum GGT levels.

CONCLUSIONS

Measuring the levels of FAEE and 5-HTOL/5-HIAA ratio provides a convenient method to detect recent, particularly binge-type, ethanol use, but these measures may have limited applicability in detecting ethanol use in traditional clinical trial settings.