LC-MS/MS analysis of plasma polyunsaturated fatty acids in type 2 diabetic patients after insulin analog initiation therapy

Development and application of a sensitive liquid chromatography-tandem mass spectrometry method for the quantitative analysis of 11 free fatty acids in human serum using a derivatisation strategy

A stable isotope dilution-liquid chromatography-tandem mass spectrometry method based on a derivatisation strategy involving an N,N'-carbonylimidazole solution (CDI) with 4-(dimethylamino)-benzenemethanamine was developed for the determination of 11 free fatty acids (FFAs) in human blood samples. Serum samples were subjected to liquid‒liquid extraction and centrifuged, and the supernatant was collected for a two-step derivatisation reaction with a CDI and 4-(dimethylamino)-aniline acetonitrile solution. The derivatised solution was separated on a ACQUITY UPLC HSS T3 column (2.1 × 50 mm, 1.8 µm) column with a mobile phase consisting of water-acetonitrile in gradient elution and then detected by tandem mass spectrometry using electrospray ionisation (ESI) and multiple reaction monitoring (MRM) in positive ion mode and quantified using the isotope internal standard method. The effects of the derivatisation reaction time, temperature and concentration of derivatisation reagents on the response values of the analytes were investigated. The optimal conditions were as follows: 1.0 mg mL-1 CDI acetonitrile solution at 25 °C for 25 min, followed by a reaction with a 1.0 mg mL-1 4-(dimethylamino)-benzenemethanamine acetonitrile solution at 70 °C for 30 min. Under the optimal conditions, the limits of detection (LODs) of the 11 FFAs were in the range of 3.0-14.0 ng mL-1; the limits of quantification (LOQs) were in the range of 8.0-45.0 ng mL-1; and the mean recoveries ranged from 83.4 to 112.8%, with intraday and interday precisions ranging from 0.7 to 9.1% and 3.7-9.5%, respectively. The experimental method is simple in terms of the pretreatment operation, accurate and reliable, and can be applied to the sensitive determination of FFAs in human blood samples.

High-Tech Methods of Cytokine Imbalance Correction in Intervertebral Disc Degeneration

An important mechanism for the development of intervertebral disc degeneration (IDD) is an imbalance between anti-inflammatory and pro-inflammatory cytokines. Therapeutic and non-therapeutic approaches for cytokine imbalance correction in IDD either do not give the expected result, or give a short period of time. This explains the relevance of high-tech medical care, which is part of specialized care and includes the use of new resource-intensive methods of treatment with proven effectiveness. The aim of the review is to update knowledge about new high-tech methods based on cytokine imbalance correction in IDD. It demonstrates promise of new approaches to IDD management in patients resistant to previously used therapies, including: cell therapy (stem cell implantation, implantation of autologous cultured cells, and tissue engineering); genetic technologies (gene modifications, microRNA, and molecular inducers of IDD); technologies for influencing the inflammatory cascade in intervertebral discs mediated by abnormal activation of inflammasomes; senolytics; exosomal therapy; and other factors (hypoxia-induced factors; lysyl oxidase; corticostatin; etc.).

Reduced levels of serum EPA and DHA identified in patients with non-small-cell lung cancer using a new rapid validated LC-MS/MS method

BACKGROUND

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been suggested to play roles in various diseases, yet there is little data on their changes in patients with non-small-cell lung cancer (NSCLC). A simple LC-MS/MS method for EPA and DHA determination is critical to exploring EPA and DHA level changes in NSCLC patients.

METHODS

25 µL of serum was mixed with 25 µL of internal standard working solution, and then 450 µL of acetonitrile for protein precipitation. After vortex and centrifugation, the supernatant was directly used for LC-MS/MS analysis. The method was well validated with linearity, precision, recovery, and matrix effect. The concentrations of EPA and DHA in serum samples from 211 NSCLC patients and 227 healthy controls were determined by this LC-MS/MS method.

RESULTS

Good separation and reliable quantification of EPA and DHA in serum samples were achieved by our method. Compared with healthy controls, serum EPA and DHA were significantly reduced in both adenocarcinoma and squamous cell carcinoma patients. The concentrations of EPA and DHA showed a progressive decrease in healthy controls, early- and advanced-stage NSCLC patients.

CONCLUSIONS

This study identified significant reductions in serum EPA and DHA in NSCLC patients through the development of an LC-MS/MS method.

Endoplasmic-reticulum-stress-induced lipotoxicity in human kidney epithelial cells

Accumulation of lipids and their intermediary metabolites under endoplasmic reticulum (ER) stress instigates metabolic failure, described as lipotoxicity, in the kidney. This study aimed to determine ER-stress-related sphingolipid and polyunsaturated fatty acid (PUFA) changes in human kidney cells. Tunicamycin (TM) was employed to induce ER stress and an ER stress inhibitor, tauroursodeoxycholic acid (TUDCA), was given to minimize cytotoxicity. Cell viability was determined by MTT assay. Sphingomyelin (SM), ceramide (CER), and PUFA levels were measured by LC-MS/MS. Glucose-regulated protein 78-kd (GRP78), cleaved caspase-3 and cyclooxygenase-1 (COX-1) levels were assessed by immunofluorescence. Cytosolic phospholipase A₂ (cPLA₂), total COX, and prostaglandin E₂ (PGE₂) were measured to evaluate changes in enzyme activity. Decreased cell viability was observed in TM treated cells. Administration of TUDCA following TM treatment significantly increased cell viability compared to TM treatment alone. Tunicamycin-induced ER stress was confirmed by significantly increased protein levels of GRP78. A significant increase was observed in C18-C24 CERs and caspase-3 activity, while a significant decrease occurred in sphingosine-1-phosphate (S1P) and cPLA₂ activity in cells treated with TM versus controls. The decrease in cPLA₂ activity was accompanied by significantly increased PUFA levels in TM treated cells. TUDCA treatment in conjunction with TM significantly decreased ER stress, C18-C24 CERs, caspase 3 activity, and increased S1P levels. Results show the buildup of long chain CERs and PUFAs in kidney cells undergoing ER stress alongside increased apoptotic activity. TUDCA administration, along with TM treatment alleviated the buildup of CERs and TM-induced apoptotic activity in kidney epithelial cells.

Reactive Thread Spray Mass Spectrometry for Localization of C═C Bonds in Free Fatty Acids: Applications for Obesity Diagnosis

Cellulose thread substrates offer a platform for microsampling and reactive ionization of free fatty acid (FFA) isomers for direct differentiation by mass spectrometry. Ambient corona discharge forms when direct current high voltage is applied to the tiny subfibers on the thread substrate in the presence of a polar spray solvent (MeOH/H2O, 2:1, v/v), facilitating chemical reactions across a C═C bond of unsaturated fatty acids. The process was applied for diagnosis of obesity, which we observed to show better discriminatory power when compared to determinations based on body mass index. Overall, the integrated reactive thread-based platform is capable of (i) microsampling and dry-state, room-temperature storage (>30 days) of the biofluids, (ii) in-capillary liquid/liquid extraction, and (iii) in situ epoxidation reactions to locate the C═C bond position in unsaturated fatty acids via reactions with reactive oxygen species present in ambient corona discharge. The study showcased the ability to correctly characterize FFAs, including degree of unsaturation, and the determination of their relative concentrations in clinical biofluid samples.

Determination of trans-fatty acids in food samples based on the pre-column fluorescence derivatization by high performance liquid chromatography

Trans-fatty acids are unsaturated fatty acids that are considered to have health risks. 1,3,5,7-Tetramethyl-8-butyrethylenediamine-difluoroboradiaza-s-indacene is a highly-sensitive fluorescent labeling reagent for carboxylic acids developed by our lab. In this study, using this pre-column fluorescent derivatization reagent, a rapid and accurate high-performance liquid chromatography-fluorescence detection method was developed for the determination of two trans-fatty acids in food samples. Under the optimized derivative conditions, two trans-fatty acids were tagged with the fluorescent labeling reagent in the presence of 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide at 25 °C for 30 min. Then, the baseline separation of trans- and cis-fatty acids and their saturated fatty acid with similar structures was achieved with less interference using a reversed-phased C₁₈ column with isocratic elution in 14 min. With fluorescence detection at λ_ex /λ_em = 490 nm/510 nm, the linear range of the trans-fatty acids was 1.0-200 nM with low detection limits in the range of 0.1-0.2 nM (signal-to-noise ratio = 3). In addition, the proposed approach was successfully applied for the detection of trans-fatty acids in food samples, and the recoveries using this method ranged from 96.02% to 109.22% with low relative standard deviations of 1.2-4.3% (n = 6). This article is protected by copyright. All rights reserved.

Diclofenac down-regulates COX-2 induced expression of CD44 and ICAM-1 in human HT29 colorectal cancer cells

Cyclooxygenase-2 (COX-2) is expressed in a variety of human colorectal cancer cells and can contribute to carcinogenesis. This study aimed to investigate the effect of diclofenac (DCF), a selective COX-2 inhibitor, on cell adhesion molecules and apoptosis in human colon adenocarcinoma cells. Levels of homing cell adhesion molecule (H-CAM, CD44), intercellular adhesion molecule-1 (ICAM-1, CD54), vascular cell adhesion molecule-1 (VCAM-1, CD106), and epithelial cell adhesion molecule (EpCAM, CD326) were evaluated in cancer cells overexpressing (HT29) or not expressing (HCT116) COX-2. Cell viability was determined by MTT assay, COX-2 protein levels and activity were assessed by immunofluorescence and fluorometric analysis, respectively. Endogenous levels of polyunsaturated fatty acids (PUFAs) were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) while expression of cell adhesion molecules was analyzed by flow cytometry. Annexin V-FITC/propidium iodide-labelling and fluorometric caspase-3 activity measurements were carried out to determine apoptosis. Flow cytometry analysis revealed that the percentage of CD44 and ICAM-1 staining in HCT116 cells was significantly lower compared to HT29 cells. In HT29 cells, phorbol 12-myristate 13-acetate (PMA) induced COX-2 expression and increased CD44 and ICAM-1 levels were down-regulated by diclofenac. Stimulation of COX-2 activity in HT29 cells via PMA significantly decreased diclofenac associated increase in PUFA levels. Treatment with both diclofenac and PMA significantly increased the number of apoptotic cells and caspase-3 activity in colon adenocarcinoma cells compared to control groups. In conclusion, diclofenac's effect to retard colorectal tumor growth and metastasis occurs in COX-2 overexpressing colon cancer cells by increased apoptosis and decreased expression of CD44 and ICAM-1.

Determination of three Unsaturated Fatty Acids in Pressure Ulcer Rats Using A UPLC-MS/MS Method

Background:

The serum levels of Docosahexaenoic Acid (DHA), Eicosapentaenoic Acid (EPA) and Arachidonic Acid (AA) under the state of Pressure Ulcers (PUs) are still unclear.

Introduction:

In order to investigate serum levels of DHA, EPA, and AA in PUs rats, an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) method was developed and validated.

Methods:

Chromatographic separation of DHA, EPA, AA was carried out on a BEH C18 column and gradient elute consisted of 5 mM ammonium acetate-0.1% formic acid and acetonitrile. Subsequently, fifty rats were divided into five groups (n=10), four PU groups (A-D) underwent various pressure and release time protocols, with group E as the control. The concentrations of DHA, EPA, AA from five groups were determined by using a validated method.

Results:

The results showed there was good linearity for DHA (327.3/283.4), EPA (301.2/257.0), and AA (303.1/258.9) within 0.05-6.4 μg/mL. In control group, the levels of DHA, AA and EPA were 1.16±0.68, 0.59±0.19 and 0.78±0.21 μg/mL. At the end of modeling, concentrations of DHA, EPA and AA were increased after long and persistent pressure (>8 h). Especially, the level of DHA was significantly higher (P<0.01) than that of control group.

Conclusion:

A stable, rA stable, reliable and accurate UPLC-MS/MS for determination of DHA, EPA, AA in blood was developed. Serum concentrations of DHA, EPA and AA were altered differently after long and persistent pressure (>8 h), and DHA is a remarkable one.eliable and accurate UPLC-MS/MS for determination of DHA, EPA, AA in blood was developed. Serum concentrations of DHA, EPA and AA were altered differently after long and persistent pressure (>8 h), and DHA is a remarkable one.

Evaluation of Plasma AA/DHA+EPA Ratio in Obese Romanian Children

The aim of the study was to evaluate the plasma profile of arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), as well to analyze the relationship of Omega 6/Omega 3 ratio with anthropo-metric parameters and insulin resistance markers.

Material and methods: Plasma levels of free fatty acids (FFAs) were measured using a high-throughput LC-MS AB Sciex4600 in 202 children (127 obese and 75 non-obese), age and sex-matched. Lipid and glucose profiles were assessed with current laboratory methods, while insulin resistance and beta-cell function were evaluated using HOMA-IR and HOMA-β respectively.

Results: In obese children, AA and AA/(DHA+EPA) ratio were significantly higher regardless of age and gender. In the lowest quartile of DHA, there was a clear trend for insulin resistance, with plasma insulin level, HOMA-IR, and HOMA-β significantly higher compared to the highest quartile of DHA. After adjustment for age and gender DHA remains a negative predictive factor for insulin resistance. Waist-to-height ratio (WHtR), a marker of visceral obesity was higher in children with a higher AA/(DHA+EPA) ratio.

Conclusions: In obese children, the AA is higher in concordance with insulin resistance. Additionally, children with a higher AA/(DHA+EPA) ratio have greater BMI, fat mass, waist circumference, and WHtR, important indicators of central adiposity, and cardio-metabolic disorders. LC/MS is a versatile tool for Omega ratio assessment, especially in children where the sample size is a limiting factor for metabolic and nutrition evaluation.

Metabolism and pharmacokinetics of a novel polyphenol fatty acid ester phloridzin docosahexaenoate in Balb/c female mice

Flavonoids are known to undergo phase II metabolism and produce metabolites with similar or stronger biological effects compared to the parent flavonoids. However, the limited cellular uptake and bioavailability restrict their clinical use. We synthesized phloridzin docosahexaenoate (PZ-DHA), a novel fatty acid ester of polyphenol, through an acylation reaction with the aim of increasing the cellular availability and stability of the parent biomolecules, phloridzin (PZ) and docosahexaenoic acid (DHA). Here, we report metabolites and pharmacokinetic parameters of PZ-DHA, determined using ultra-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry. PZ-DHA was taken-up by human (MDA-MB-231, MDA-MB-468, and MCF-7) and mouse (4T1) mammary carcinoma and human non-malignant mammary epithelial cells (MCF-10A) in cellular uptake assays. Our results suggested that the acylation improves the cellular uptake of PZ and stability of DHA within cells. In mouse hepatic microsomal assays, two major glucuronides of PZ-DHA, PZ-DHA-4-O-glucuronide and PZ-DHA-4'-O-glucuronide (MW = 923.02 g/mol), were detected. One tri-methylated- (4,4',6'-O-trimethyl-PZ-DHA) (MW = 788.88 g/mol) and one di-sulphated- (PZ-DHA-4,4'-O-disulphide) PZ-DHA metabolite (MW = 906.20 g/mol) were also identified. Intraperitoneal injections of PZ-DHA (100 mg/kg) into Balb/c female mice was rapidly absorbed with a serum C_max and T_max of 23.7 µM and 60 min, respectively, and rapidly eliminated (t_1/2 = 28.7 min). PZ-DHA and its metabolites are readily distributed throughout the body (V_d = 57 mL) into many organs. We identified in vitro and in vivo metabolites of PZ-DHA, which could be tested for potential use to treat diseases such as cancer in multiple organ systems.

Bioactive lipids in intervertebral disc degeneration and its therapeutic implications

Intervertebral disc (IVD) degeneration is not uncommon. It is estimated that approximately >60% of individuals above the age of 40 years suffer from IVD degeneration. Shan et al. showed that hyperglycemia can enhance apoptosis of anulus fibrosis cells in a JNK pathway and p38 mitogen-activated protein kinase (MAPK) pathway dependent fashion. Recent studies showed that IVD degeneration could be an inflammatory condition characterized by increased production of matrix metalloproteinases, TNF-α, nitric oxide, IL-6, IL-17, IL-9, and prostaglandin E2, and decreased formation of anti-inflammatory molecules such as lipoxin A4. This imbalance between pro- and anti-inflammatory molecules seem to activate JNK pathway and p38 MAPK pathway to induce apoptosis of anulus fibrosis and nucleus pulposus cells. The activation of production of PGE2 (due to activation of COX-2 pathway) seems to be dependent on p38/c-Fos and JNK/c-Jun activation in an AP-1-dependent manner. These results imply that suppressing pro-inflammatory events in the disc by either augmenting anti-inflammatory events or suppressing production of pro-inflammatory molecules or both may form a logical step in the prevention and management of IVD degeneration.

Development and Validation of a LC⁻MS/MS-Based Assay for Quantification of Free and Total Omega 3 and 6 Fatty Acids from Human Plasma

Few high-performance liquid chromatography⁻tandem mass spectrometry (LC-MS/MS) methods have been developed for the full quantitation of fatty acids from human plasma without derivatization. Therefore, we propose a method that requires fewer sample preparation steps, which can be used for the quantitation of several polyunsaturated fatty acids in human plasma. The method offers rapid, accurate, sensitive, and simultaneous quantification of omega 3 (α-linolenic, eicosapentaenoic, and docosahexaenoic acids) and omega 6 fatty acids (arachidonic and linoleic acids) using high-performance LC-MS/MS. The selected fatty acids were analysed in lipid extracts from both free and total forms. Chromatographic separation was achieved using a reversed phase C18 column with isocratic flow using ammonium acetate for improving negative electrospray ionization (ESI) response. Mass detection was performed in multiple reaction monitoring (MRM) mode, and deuterated internal standards were used for each target compound. The limits of quantification were situated in the low nanomolar range, excepting linoleic acid, for which the limit was in the high nanomolar range. The method was validated according to the U.S. Department of Health and Human Services guidelines, and offers a fast, sensitive, and reliable quantification of selected omega 3 and 6 fatty acids in human plasma.

A Validation and Estimation of Total Eicosapentaenoic and Docosahexaenoic acids Using LC-MS/MS with Rapid Hydrolysis Enzymatic Method for Hydrolysis of Omega Lipids in Human Plasma and its Application in the Pharmacokinetic Study

Background:

In this study, we have developed a novel, rapid enzymatic hydrolysis method for conversion of omega lipids (omega fatty acid triglycerides, phospholipids, omega conjugates) in to free fatty acids at room temperature using lipase and esterase enzymes. </P><P> Objective: To develop simple enzymatic hydrolysis and rapid sample extraction method for quantification of free (un-esterified) and conjugated (esterified) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) to provide the total EPA and DHA lipids present in human plasma. Quantification of total EPA/DHA was performed using liquid chromatography and tandem mass spectrometer instrument.

Methods:

The plasma sample is digested with lipase and esterase enzymes and extracted by using combined precipitation and liquid-liquid techniques. The LC-MS/MS method was optimized using EPA-D5 and DHA-D5 as labeled internal standards for EPA/DHA respectively. The analytical method is validated, utilized for simultaneous quantification of total EPA and DHA lipids in plasma collected from healthy human volunteers clinical study.

Results:

The reproducibility of the established enzymatic hydrolysis method was demonstrated by incurred sample reanalysis and the results for total EPA and DHA lipid were 93.33% and 96.67% respectively. The pharmacokinetic and statistical analysis was performed using baseline corrected concentration of total EPA and DHA lipids.

Conclusion:

The enzymatic hydrolysis method for conversion of omega fatty acid triglycerides, phospholipids, omega conjugates in to free fatty acid was reported first time for the quantitative application. The shorter time for sample workup procedure, simple enzymatic hydrolysis at room temperature and 3 minutes chromatography run time are well suitable for bioavailability/ bioequivalence studies.

The validation & verification of an LC/MS method for the determination of total docosahexaenoic acid concentrations in canine blood serum

Docosahexaenoic acid (DHA), is an omega 3 fatty acid (n-3 FA) that has been shown to play a role in canine growth and physiological integrity and improvements in skin and coat condition. However, potential adverse effects of n-3 FA specifically, impaired cellular immunity has been observed in dogs fed diets with elevated levels of n-3 FA. As such, a safe upper limit (SUL) for total n-3 FAs (DHA and EPA) in dogs has been established. Considering this SUL, sensitive methods detecting DHA in blood serum as a biomarker when conducting n-3 FA supplementation trials involving dogs are required. In this study, an LC-ESI-MS/MS method of DHA detection in dog serum was validated and verified. Recovery of DHA was optimized and parallelism tests were conducted with spiked samples demonstrating that the serum matrix did not interfere with quantitation. The stability of DHA in serum was also investigated, with -80 °C considered suitable when storing samples for up to six months. The method was linear over a calibration range of 1-500 μg/mL and precision and accuracy were found to meet the requirements for validation. This method was verified in an alternative laboratory using a different analytical system and operator, with the results meeting the criteria for verification.

Validation and Verification of a Liquid Chromatography-Mass Spectrometry Method for the Determination of Total Docosahexaenoic Acid in Pig Serum

The paper presents the validation and verification of an analytical method for the determination of total docosahexaenoic acid (DHA) in pig serum by liquid chromatography-electrospray ionization-tandem mass spectrometry. The characteristics studied during the validation included precision and accuracy, limit of quantitation (LOQ), selectivity, calibration range and linearity, parallelism, and stability. A separate verification study was also performed. The method was linear over the range. Precision and accuracy met acceptance criteria at all levels, and the LOQ was determined as 1 μg/mL. Parallelism experiments were conducted to show that there was no bias introduced in using a surrogate matrix to quantify DHA. Recoveries of free DHA were obtained for quality control samples, and stability studies were conducted over 1, 7, 31, and 180 days. The results of the verification study were in line with the validation study, and in conclusion, the method was deemed fit for purpose for measuring total DHA in pig serum.

Omega-3 Hastens and Omega-6 Delays the Progression of Neuropathology in a Murine Model of Familial ALS

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a progressive disease of motor neurons that has no cure or effective treatment. Any approach that could sustain minor motor function during terminal stages would improve quality of life.

OBJECTIVE

We examined the impact of omega-3 (Ω-3) and Ω-6, on motor neuron function in mice expressing mutant human superoxide dismutase-1 (SOD-1), which dominantly confers familial ALS and induces a similar sequence of motor neuron decline and eventual death when expressed in mice.

METHOD

Mice received standard diets supplemented with equivalent amounts of Ω-3 and Ω-6 or a 10x increase in Ω-6 with no change in Ω-3 commencing at 4 weeks of age. Motor function and biochemical/histological parameters were assayed by standard methodologies.

RESULTS

Supplementation with equivalent Ω-3 and Ω-6 hastened motor neuron pathology and death, while 10x Ω-6 with no change in Ω-3 significantly delayed motor neuron pathology, including preservation of minor motor neuron function during the terminal stage.

CONCLUSION

In the absence of a cure or treatment, affected individuals may resort to popular nutritional supplements such as Ω-3 as a form of "self-medication". However, our findings and those of other laboratories indicate that such an approach could be harmful. Our findings suggest that a critical balance of Ω-6 and Ω-3 may temporarily preserve motor neuron function during the terminal stages of ALS, which could provide a substantial improvement in quality of life for affected individuals and their caregivers.

A novel liquid chromatography/tandem mass spectrometry (LC-MS/MS) based bioanalytical method for quantification of ethyl esters of Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) and its application in pharmacokinetic study

Omega-3 fatty acids are clinically useful and the two marine omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are prevalent in fish and fish oils. Omega-3 fatty acid formulations should undergo a rigorous regulatory step in order to obtain United States Food and Drug Administration (USFDA) approval as prescription drug. In connection with that, despite quantifying EPA and DHA fatty acids, there is a need for quantifying the level of ethyl esters of them in biological samples. In this study, we make use of reverse phase high performance liquid chromatography coupled with mass spectrometry (RP-HPLC-MS)technique for the method development. Here, we have developed a novel multiple reaction monitoring method along with optimized parameters for quantification of EPA and DHA as ethyl esters. Additionally, we attempted to validate the bio-analytical method by conducting the sensitivity, selectivity, precision accuracy batch, carryover test and matrix stability experiments. Furthermore, we also implemented our validated method for evaluation of pharmacokinetics of omega fatty acid ethyl ester formulations.

Effect of dietary n-3 fatty acids supplementation on fatty acid metabolism in atorvastatin-administered SHR.Cg-Leprcp/NDmcr rats, a metabolic syndrome model

The effects of cholesterol-lowering statins, which substantially benefit future cardiovascular events, on fatty acid metabolism have remained largely obscured. In this study, we investigated the effects of atorvastatin on fatty acid metabolism together with the effects of TAK-085 containing highly purified eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) ethyl ester on atorvastatin-induced n-3 polyunsaturated fatty acid lowering in SHR.Cg-Lepr^cp/NDmcr (SHRcp) rats, as a metabolic syndrome model. Supplementation with 10mg/kg body weight/day of atorvastatin for 17 weeks significantly decreased plasma total cholesterol and very low density lipoprotein cholesterol. Atorvastatin alone caused a subtle change in fatty acid composition particularly of EPA and DHA in the plasma, liver or erythrocyte membranes. However, the TAK-085 consistently increased both the levels of EPA and DHA in the plasma, liver and erythrocyte membranes. After confirming the reduction of plasma total cholesterol, 300mg/kg body weight/day of TAK-085 was continuously administered for another 6 weeks. Supplementation with TAK-085 did not decrease plasma total cholesterol but significantly increased the EPA and DHA levels in both the plasma and liver compared with rats administered atorvastatin only. Supplementation with atorvastatin alone significantly decreased sterol regulatory element-binding protein-1c, Δ5- and Δ6-desaturases, elongase-5, and stearoyl-coenzyme A (CoA) desaturase-2 levels and increased 3-hydroxy-3-methylglutaryl-CoA reductase mRNA expression in the liver compared with control rats. TAK-085 supplementation significantly increased stearoyl-CoA desaturase-2 mRNA expression. These results suggest that long-term supplementation with atorvastatin decreases the EPA and DHA levels by inhibiting the desaturation and elongation of n-3 fatty acid metabolism, while TAK-085 supplementation effectively replenishes this effect in SHRcp rat liver.

Localized delivery of low-density lipoprotein docosahexaenoic acid nanoparticles to the rat brain using focused ultrasound

Focused ultrasound exposures in the presence of microbubbles can achieve transient, non-invasive, and localized blood-brain barrier (BBB) opening, offering a method for targeted delivery of therapeutic agents into the brain. Low-density lipoprotein (LDL) nanoparticles reconstituted with docosahexaenoic acid (DHA) could have significant therapeutic value in the brain, since DHA is known to be neuroprotective. BBB opening was achieved using pulsed ultrasound exposures in a localized brain region in normal rats, after which LDL nanoparticles containing the fluorescent probe DiR (1,1'-Dioctadecyl-3,3,3',3'-Tetramethylindotricarbocyanine Iodide) or DHA were administered intravenously. Fluorescent imaging of brain tissue from rats administered LDL-DiR demonstrated strong localization of fluorescence signal in the exposed hemisphere. LDL-DHA administration produced 2 × more DHA in the exposed region of the brain, with a corresponding increase in Resolvin D1 levels, indicating DHA was incorporated into cells and metabolized. Histological evaluation did not indicate any evidence of increased tissue damage in exposed brain regions compared to normal brain. This work demonstrates that localized delivery of DHA to the brain is possible using systemically-administered LDL nanoparticles combined with pulsed focused ultrasound exposures in the brain. This technology could be used in regions of acute brain injury or as a means to target infiltrating tumor cells in the brain.

Analysis of polyunsaturated fatty acids and the omega-6 inflammatory pathway in hepatic ischemia/re-perfusion injury

The aim of the present study was to assess omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs) in liver tissue and evaluate changes in the n‑6-associated inflammatory pathway following liver ischemia/re‑perfusion (IR) injury. Male Wistar rats which were allowed free access to standard rat chow were included in the study. Blood vessels supplying the median and left lateral hepatic lobes were occluded with an arterial clamp for 60 min, followed by 60 min of re‑perfusion. Levels of arachidonic acid (AA, C20:4n‑6), dihomo‑gamma‑linolenic acid (DGLA, C20:3n‑6), eicosapentaenoic acid (EPA, C20:5n‑3) and docosahexaenoic acid (DHA, C22:6n‑3) in liver tissue were determined by an optimized multiple reaction monitoring method using ultra fast‑liquid chromatography coupled with tandem mass spectrometry. Phospholipase A2 (PLA2), cyclooxygenase (COX) and prostaglandin E2 (PGE2) were measured in tissue samples to evaluate changes in the n‑6 inflammatory pathway. Total histopathological score of cellular damage were significantly increased following hepatic IR injury. n‑3 and n‑6 PUFA levels were significantly increased in post‑ischemic liver tissue compared to those in non‑ischemic controls. No significant difference was observed in the AA/DHA and AA/EPA ratio in post‑ischemic liver tissues compared with that in the control. Tissue activity of PLA2 and COX as well as PGE2 levels were significantly increased in post‑ischemic liver tissues compared to those in non‑ischemic controls. The results of the present study suggested that increased hydrolysis of fatty acids via PLA2 triggers the activity of COX and leads to increased PGE2 levels. Future studies evaluating agents which block the formation of eicosanoids derived from n‑6 PUFAs may facilitate the development and application of treatment strategies in liver injury following IR.

N-3 PUFA increase bioavailability and function of endothelial progenitor cells

BACKGROUND AND AIMS

Recent data suggest that n-3 PUFA exert beneficial effects on endothelial progenitor cell (EPC) biology. We sought to investigate whether these effects might be mediated by enhanced EPC in vitro function and/or in vivo bioavailability.

METHODS AND RESULTS

CACs and late-outgrowth EPCs were isolated from peripheral blood mononuclear cells obtained from 12 donor buffy-coats. The effect of n-3 PUFA (EPA:DHA = 0.9:1.5; 9 μM EPA plus 15 μM DHA) was tested on CAC/EPC viability, function (tube-formation) and pro-inflammatory molecule expression. Circulating EPC (cells positive for CD34, CD133 and kinase insert domain receptor - KDR cell-surface antigens by flow cytometry) number was evaluated in 20 healthy subjects (10 F/10 M, 32 ± 5 years), randomized to receive 4 mackerel or sardine portions per week for 6 weeks followed by a 6 week free-diet period. N-3 PUFA improved CAC and late-outgrowth EPC viability (p < 0.05) and the capacity to form tube-like structures in CACs (+38%; p < 0.05) and late-outgrowth EPCs (+15%; p < 0.05). ICAM-1 expression was reduced in both CACs (p < 0.05) and late-outgrowth EPCs (p < 0.05) and VCAM-1 in late-outgrowth EPCs (p < 0.005). N-3 PUFA significantly decreased TNF-α and MCP-1 expression in CACs and IL-8, TNF-α and MCP-1 in late-outgrowth EPCs (p < 0.05). Circulating EPC number significantly improved after 6 weeks of a fish-enriched diet (p < 0.01) and returned to baseline levels after a 6 week free-diet period (p < 0.01). Plasma EPA levels were independently and positively associated with EPC levels (p < 0.005).

CONCLUSION

Our findings support the case of a beneficiary role played by n-3 PUFA in EPC function and bioavailability.

An Optimized High Throughput Clean-Up Method Using Mixed-Mode SPE Plate for the Analysis of Free Arachidonic Acid in Plasma by LC-MS/MS

A high throughput sample preparation method was developed utilizing mixed-mode solid phase extraction (SPE) in 96-well plate format for the determination of free arachidonic acid in plasma by LC-MS/MS. Plasma was mixed with 3% aqueous ammonia and loaded into each well of 96-well plate. After washing with water and methanol sequentially, 3% of formic acid in acetonitrile was used to elute arachidonic acid. The collected fraction was injected onto a reversed phase column at 30°C with mobile phase of acetonitrile/water (70 : 30, v/v) and detected by LC-MS/MS coupled with electrospray ionization (ESI) in multiple reaction monitoring (MRM) mode. The calibration curve ranged from 10 to 2500 ng/mL with sufficient linearity (r (2) = 0.9999). The recoveries were in the range of 99.38% to 103.21% with RSD less than 6%. The limit of detection is 3 ng/mL.

Induction of omega 6 inflammatory pathway by sodium metabisulfite in rat liver and its attenuation by ghrelin

Background

Sodium metabisulfite is commonly used as preservative in foods but can oxidize to sulfite radicals initiating molecular oxidation. Ghrelin is a peptide hormone primarily produced in the stomach and has anti-inflammatory effects in many organs. This study aimed to assess endogenous omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs) in rat peripheral organs following sodium metabisulfite treatment and determine the possible effect of ghrelin on changes in n-6 inflammatory pathway.

Methods

Male Wistar rats included in the study were allowed free access to standard rat chow. Sodium metabisulfite was given by gastric gavage and ghrelin was administered intraperitoneally for 5 weeks. Levels of arachidonic acid (AA, C20:4n-6), dihomo-gamma-linolenic acid (DGLA, C20:3n-6), eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3) in liver, heart and kidney tissues were determined by an optimized multiple reaction monitoring (MRM) method using ultra fast-liquid chromatography (UFLC) coupled with tandem mass spectrometry (MS/MS). Cyclooxygenase (COX) and prostaglandin E2 (PGE2) were measured in tissue samples to evaluate changes in n-6 inflammatory pathway.

Results

Omega-6 PUFA levels, AA/DHA and AA/EPA ratio were significantly increased in liver tissue following sodium metabisulfite treatment compared to controls. No significant change was observed in heart and kidney PUFA levels. Tissue activity of COX and PGE2 levels were also significantly increased in liver tissue of sodium metabisulfite treated rats compared to controls. Ghrelin treatment decreased n-6 PUFA levels and reduced COX and PGE2 levels in liver tissue of sodium metabisulfite treated rats.

Conclusion

Current results suggest that ghrelin exerts anti-inflammatory action through modulation of n-6 PUFA levels in hepatic tissue.

Profiling of fatty acids composition in suet oil based on GC-EI-qMS and chemometrics analysis

Fatty acid (FA) composition of suet oil (SO) was measured by precolumn methylesterification (PME) optimized using a Box-Behnken design (BBD) and gas chromatography/electron ionization-quadrupole mass spectrometry (GC-EI-qMS). A spectral library (NIST 08) and standard compounds were used to identify FAs in SO representing 90.89% of the total peak area. The ten most abundant FAs were derivatized into FA methyl esters (FAMEs) and quantified by GC-EI-qMS; the correlation coefficient of each FAME was 0.999 and the lowest concentration quantified was 0.01 μg/mL. The range of recovery of the FAMEs was 82.1%-98.7% (relative standard deviation 2.2%-6.8%). The limits of quantification (LOQ) were 1.25-5.95 μg/L. The number of carbon atoms in the FAs identified ranged from 12 to 20; hexadecanoic and octadecanoic acids were the most abundant. Eighteen samples of SO purchased from Qinghai, Anhui and Jiangsu provinces of China were categorized into three groups by principal component analysis (PCA) according to the contents of the most abundant FAs. The results showed SOs samples were rich in FAs with significantly different profiles from different origins. The method described here can be used for quality control and SO differentiation on the basis of the FA profile.

Plasma polyunsaturated fatty acid profile and delta-5 desaturase activity are altered in patients with type 2 diabetes

OBJECTIVE

The association between imbalance of polyunsaturated fatty acids (PUFAs), especially low plasma n-3 to n-6 PUFA ratio, and risk of cardiovascular diseases is well known. A balance of plasma PUFAs is determined not only by dietary fatty acid intake, but also by the endogenous fatty acid metabolism, which could be dysregulated by diabetes. In this study, we investigated the plasma n-3 and n-6 PUFA profile and fatty acid desaturase activity in patients with type 2 diabetes (T2D).

MATERIALS/METHODS

The subjects were 396 patients with T2D and 122 healthy controls. Plasma eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), and dihomo-γ-linolenic acid (DGLA) levels were measured by capillary gas chromatography.

RESULTS

Plasma DHA, AA, and DGLA levels were significantly higher, and EPA levels tended to be lower in patients with T2D than in the controls. Patients with T2D also exhibited significantly lower EPA/AA, DHA/AA, and (EPA+DHA)/AA ratios, and a higher AA/DGLA ratio than the controls. Multiple regression analyses, including age, sex, body mass index, and metabolic parameters in the total population, revealed that the presence of T2D was independently associated with elevated plasma DHA, AA, and DGLA levels and decreased EPA/AA, DHA/AA, and (EPA+DHA)/AA ratios. Furthermore, T2D was independently and positively related to the AA/DGLA ratio, which serves as an estimate of delta (Δ)-5 desaturase activity.

CONCLUSIONS

Elevated plasma AA levels and decreased n-3 PUFA/AA ratios in T2D are attributable, at least partly, to Δ5 desaturase activation.

A pilot study investigating early postoperative changes of plasma polyunsaturated fatty acids after laparoscopic sleeve gastrectomy

Background

This study aimed to determine early postoperative changes of plasma polyunsaturated fatty acids (PUFAs) following laparoscopic sleeve gastrectomy (LSG).

Methods

Ten obese patients (mean BMI: 51.10 ± 11.59 kg/m²) underwent LSG and eleven normal weight control patients (mean BMI: 24.37 ± 2.33 kg/m²) underwent laparoscopic abdominal surgery. Fasting blood samples were collected prior to surgery, at day 1 after surgery and after postoperation oral feeding. Plasma levels of arachidonic acid (AA, C20:4n6), dihomo-gamma-linolenic acid (DGLA, C20:3n6), eicosapentaenoic acid (EPA, C20:5n3) and docosahexaenoic acid (DHA, C22:6n3) were determined by an optimized multiple reaction monitoring (MRM) method using ultra fast-liquid chromatography (UFLC) coupled with tandem mass spectrometry (MS/MS). Prostaglandin E₂ (PGE2) was measured in serum samples by enzyme immunoassay.

Results

A significant decrease was observed in insulin and HOMA IR levels in sleeve gastrectomy patients after postoperation oral feeding compared to preoperation. Plasma AA levels and AA/EPA ratio were significantly increased in sleeve gastrectomy patients after postoperation oral feeding compared to postoperation day 1. Serum PGE2 levels and AA/DHA ratio was significantly higher in sleeve gastrectomy patients at preoperation, postoperation day 1 and after postoperation oral feeding when compared to control group patients.

Conclusion

Increased peripheral insulin sensitivity associated with LSG may play a role in the significant increase of plasma AA levels in sleeve gastrectomy patients following postoperation oral feeding. The significant increase in PGE2 levels and AA/DHA ratio in sleeve gastrectomy group patients also confirms the presence of a proinflammatory state in obesity.

Inhibition of neutral sphingomyelinase decreases arachidonic acid mediated inflammation in liver ischemia-reperfusion injury

This study aimed to determine the role of selective neutral sphingomyelinase (N-SMase) inhibition on arachidonic acid (AA) mediated inflammation following liver ischemia-reperfusion (IR) injury. Selective N-SMase inhibitor was administered via intraperitoneal injections. Liver IR injury was created by clamping blood vessels supplying the median and left lateral hepatic lobes for 60 min, followed by 60 min reperfusion. Levels of AA in liver tissue were determined by multiple reaction monitoring (MRM) using ultra fast-liquid chromatography (UFLC) coupled with tandem mass spectrometry (MS/MS). Phospholipase A₂ (PLA₂), cyclooxygenase (COX) and prostaglandin E₂ (PGE₂) were measured in liver tissue. Arachidonic acid levels, activity of PLA₂, COX and PGE₂ levels were significantly increased in postischemic liver tissue compared to nonischemic controls. N-SMase inhibition significantly decreased COX activity and PGE₂ levels in postischemic liver. Future studies evaluating agents blocking N-SMase activity can facilitate the development of treatment strategies to alleviate inflammation in liver I/R injury.