Surplus fatty acid synthesis increases oxidative stress in adipocytes and lnduces lipodystrophy.

Adipocytes are the primary sites for fatty acid storage, but the synthesis rate of fatty acids is very low. The physiological significance of this phenomenon remains unclear. Here, we show that surplus fatty acid synthesis in adipocytes induces necroptosis and lipodystrophy. Transcriptional activation of FASN elevates fatty acid synthesis, but decreases NADPH level and increases ROS production, which ultimately leads to adipocyte necroptosis. We identify MED20, a subunit of the Mediator complex, as a negative regulator of FASN transcription. Adipocyte-specific male Med20 knockout mice progressively develop lipodystrophy, which is reversed by scavenging ROS. Further, in a murine model of HIV-associated lipodystrophy and a human patient with acquired lipodystrophy, ROS neutralization significantly improves metabolic disorders, indicating a causal role of ROS in disease onset. Our study well explains the low fatty acid synthesis rate in adipocytes, and sheds light on the management of acquired lipodystrophy.

A novel automated multi-cycle magnetic solid-phase extraction coupled to LC-MS/MS to study the disorders of six functional B vitamins in patients with gastroenterology and hyperhomocysteinemia.

B vitamins are essential for human life and their disorders can cause a variety of diseases. Solid-phase extraction (SPE) coupled to LC-MS/MS is a preferred technique for determining multiple B vitamins, however, their complexity in real biological matrices makes it hard to achieve satisfactory recovery and accuracy when simultaneous detection. In this study, a novel automated multi-cycle magnetic SPE (MSPE) coupled to the LC-MS/MS method was established using a mixed-mode anion exchange magnetic adsorbent for the simultaneous extraction of six functional B vitamins, including methylmalonic acid, riboflavin, pantothenic acid, 4-pyridoxic acid, folic acid, and 5-methyltetrahydrofolate. After three consecutive MSPE cycles, the recoveries of all analytes were between 51.5% and 89.6%. The method exhibited excellent sensitivity and linearity, with a dynamic range of 200-fold (R > 0.99 for all analytes), exceptional accuracy (ranging between 95.4% and 105.6%) and precision (with RSDs ≤ 6.2%) without significant matrix effects or interferences. Compared to manual SPE method, the automated multi-cycle MSPE method has better feasibility and greater vitamin coverage. It shows a high correlation with the manual method for the detection of 5-methyltetrahydrofolate and folate (R > 0.99). A study of patients from the gastroenterology department showed that those undergoing surgery and those with malignancies may be at risk of folate deficiency. In addition, patients with hyperhomocystinemia had higher levels of methylmalonic acid and lower levels of 5-methyltetrahydrofolate, which correlated with homocysteine levels (R = 0.404 and -0.311, respectively) and showed dose-response relationships. This method is highly automated and cost-effective, with minimal systematic error, making it suitable for the analysis of clinical samples.

Simple and fast determination of tetrodotoxin in human plasma based on hydrophilic-interaction/ion-exchange mixed-mode solid phase extraction combined with liquid chromatography-tandem mass spectroscopy.

In this study, we developed and validated a simple, fast and sensitive LC-MS/MS method for the measurement of tetrodotoxin (TTX) in human plasma. Three HILIC-type solid phase extraction (SPE) carriers (PSA, silica, Siphila i HILIX) with different stationary phase functional groups were compared. The Siphila i HILIX SPE plate containing multi-carboxyl groups was finally selected due to obviously better extraction recovery of TTX (about 80% of recovery from plasma samples) than the other two and no significant matrix effects were observed, which was speculated to have mixed-mode synergistic effects of hydrophilic interaction and ion exchange. 100µL plasma sample was precipitated rapidly with acetonitrile containing 1% trichloroacetic acid, and filtrates were loaded onto Siphila i HILIX 96 well SPE plate. After washed with 95% acetonitrile, TTX was eluted with 200µL of 50% acetonitrile containing 1% trichloroacetic acid. 2µL of elution solution was directly injected into LC-MS/MS and the total run time on a BEH amide column was 4.5 min. The method avoids the evaporation and ultrafiltration processes which is simple and timesaving (<30 min). TTX and internal standard (arginine-15N4) were monitored in positive mode using m/z 320.3→162.2 (quantification transition for TTX), 320.3→284.1 (confirmation transition for TTX) and 179.2→63.0 (transition for IS), respectively. The method was linear in the range of 0.1-20 ng/mL for TTX with the low limit of quantification (S/N > 10) of 0.1 ng/mL; the intra- and inter-assay accuracies were in the range of 98.5%-99.8% (relative standard deviations, RSDs ≤ 5.92%) and 98.8-99.5% (RSDs ≤ 6.23%), respectively. Biases of spiking analysis were ranged from -7.00% to 7.43% for healthy human plasma samples (RSDs ≤ 8.83%) and from -5.00% to 3.93% for hemolytic, high triglyceride, high cholesterol and high bilirubin plasma samples (RSDs ≤ 6.40%), which proved the good anti-interference property of the method. The results showed that the method is sensitive, accurate, specific, reliable, and can be used to monitor the concentration of TTX in plasma to meet the needs of clinical research and poisoning screening.

Comparison of four different immunoassays and a rapid isotope-dilution liquid chromatography-tandem mass spectrometry assay for serum folate.

OBJECTIVES: Accurate measurement of serum folate is essential for the diagnosis and management of various disorders. This study aims to investigate the between-method differences of four immunoassays and a rapid isotope-dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) method. METHODS: Roche Cobas (USA), Abbott Alinity i2000 (USA), Beckman Coulter Access (USA), Mindray CL-6000i (China), and the ID-LC-MS/MS method were compared using 46 human serum samples. The results were analysed by Passing-Bablok regressions and Bland-Altman plots. A bias of 13.31% based on biological variation was used as the bias criterion. RESULTS: All the within-run and total coefficients of variation (CVs) met the specification. The folate concentrations determined by all the assays were significantly different (p=0.0028). All assays had correlation coefficients over 0.97 with each other. The 95% confidence intervals (CIs) for the slope seldom contained 1 and few 95% CIs for the intercept contained 0 in the regression equations. Compared to ID-LC-MS/MS, the biases of all assays ranged from -20.91 to 13.56 nmol/L, and the mean relative biases ranged from -9.85 to 40.33%. The predicted mean relative biases at the medical decision levels rarely met the criterion. CONCLUSIONS: Assays for serum folate had good correlations with each other but lacked good agreement. The accuracy and consistency of assays for serum folate should be measured and assessed routinely. Standardization work to improve the accuracy of serum folate assays, such as the extension of traceability to reference methods or materials, calibration standardization efforts, and assay-adjusted cut-offs should be promoted.

Fasting serum fructose is associated with risk of gestational diabetes mellitus.

OBJECTIVE: To investigate the association of fasting serum fructose concentrations and the incidence of GDM. RESEARCH DESIGN AND METHODS: Five hundred twenty six pregnant women who attended the obstetric clinic of Xinhua Hospital, Chongming Branch were recruited prospectively from September 2019 to November 2020. Fasting serum fructose concentrations were measured by a validated liquid chromatography-tandem mass spectrometry method. GDM was diagnosed according to the criteria of the IADPSG. Independent sample t-test was used to compare the differences between groups. Multiple stepwise regression analysis was used to estimate the associations of serum fructose and other variables. Multivariate logistic regression models were adopted to evaluate the odds ratios (ORs) for GDM. RESULTS: Of the 526 pregnant women, 110 were diagnosed with GDM. Fasting fructose concentrations were increased significantly in GDM patients compared to those without GDM (1.30 ug/ml vs 1.16 ug/ml, p<0.001). Fasting fructose concentration was independently associated with GDM after adjusting the potential confounders, 1 ug/ml increase in fasting serum fructose level was associated with an 81.1% increased risk of GDM (1.811, [1.155-2.840]). Taking fructose <1.036 ug/ml as the reference, the OR for GDM was significantly higher in fructose ≥1.036 ug/ml group (OR, 1.669; 95% CI, 1.031-2.701) after all the potential confounders were adjusted. CONCLUSIONS: Increased fasting serum fructose levels were independently associated with the incidence of GDM.

Euphornin L promotes lipid clearance by dual regulation of LDLR and PCSK9.

Our previous study identified euphornin L as an active lipid-lowering compound in high-fat diet-fed Golden Syrian hamsters. The aim of the present study was to investigate the mechanisms underlying the lipid-lowering effects of euphornin L. Euphornin L in HepG2 cells was assessed via DiI-LDL update assays and found to increase LDL-update and LDLR protein levels. RNA interference assays demonstrated that its LDL-update effects were LDLR-dependent. Dual luciferase reporter and mRNA stability assays revealed that euphornin L had little effect on LDLR mRNA transcription but lengthened the half-life of LDLR mRNA by activating ERK protein in cells. Euphornin L decreased the secretion of PCSK9 protein and alleviated PCSK9-mediated LDLR protein degradation. In vivo experiments in hamsters, which were treated with euphornin L (30 mg/kg/day) for 3 weeks, confirmed these findings. LDLR protein levels in liver tissue were upregulated, while PCSK9 protein levels in serum were downregulated. Altogether, the present study demonstrated that euphornin L increased LDLR protein levels by dual regulation of LDLR mRNA and PCSK9 protein, and represented an active compound for lipid-lowering drug development.

Identification of circulating sphingosine kinase-related metabolites for prediction of type 2 diabetes.

BACKGROUND: Sphingosine Kinase (SphK) that catalyzes sphingosine (Sph) to sphingosine 1-phosphate (S1P), plays a key role in both sphingolipid metabolism and cellular signaling. While SphK has been implicated in type 2 diabetes mellitus (T2DM), it is unexplored in humans. Herein, we investigated whether circulating SphK-related metabolites are associated with T2DM incidence in an established prospective cohort. METHODS: Levels of SphK-related sphingolipid metabolites, including Sph, S1P, dihydrosphingosine (dhSph) and dihydro-S1P (dhS1P) in serum were measured by targeted-lipidomic analyses. By accessing to an established prospective cohort that involves a total of 2486 non-diabetic adults at baseline, 100 subjects who developed T2DM after a mean follow-up of 4.2-years, along with 100 control subjects matched strictly with age, sex, BMI and fasting glucose, were randomly enrolled for the present study. RESULTS: Comparison with the control group, medians of serum dhS1P and dhS1P/dhSph ratio at baseline were elevated significantly prior to the onset of T2DM. Each SD increment of dhS1P and dhS1P/dhSph ratio was associated with 53.5% and 54.1% increased risk of incident diabetes, respectively. The predictive effect of circulating dhS1P and dhS1P/dhSph ratio on T2DM incidence was independent of conventional risk factors in multivariate regression models. Furthermore, combination of serum dhS1P and dhS1P/dhSph ratio with conventional clinical indices significantly improved the accuracy of T2DM prediction (AUROC, 0.726), especially for normoglycemic subjects (AUROC, 0.859). CONCLUSION: Circulating levels of dhS1P and dhS1P/dhSph ratio are strongly associated with increased risk of T2DM, and could serve as a useful biomarker for prediction of incident T2DM in normoglycemic populations.

Direct analysis in real time-mass spectrometry for rapid quantification of five anti-arrhythmic drugs in human serum: application to therapeutic drug monitoring.

Therapeutic drug monitoring (TDM) is necessary for the optimal administration of anti-arrhythmic drugs in the treatment of heart arrhythmia. The present study aimed to develop and validate a direct analysis in real time tandem mass spectrometry (DART-MS/MS) method for the rapid and simultaneous determination of five anti-arrhythmic drugs (metoprolol, diltiazem, amiodarone, propafenone, and verapamil) and one metabolite (5-hydroxy(OH)-propafenone) in human serum. After the addition of isotope-labeled internal standards and protein precipitation with acetonitrile, anti-arrhythmic drugs were ionized by DART in positive mode followed by multiple reaction monitoring (MRM) detection. The use of DART-MS/MS avoided the need for chromatographic separation and allowed rapid and ultrahigh throughput analysis of anti-arrhythmic drugs in a total run time of 30 s per sample. The DART-MS/MS method yielded satisfactory linearity (R2 ≥ 0.9906), accuracy (86.1-109.9%), and precision (≤ 14.3%) with minimal effect of biological matrixes. The method was successfully applied to analyzing 30 clinical TDM samples. The relative error (RE) of the concentrations obtained by DART-MS/MS and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was within ± 13%. This work highlights the potential usefulness of DART for the rapid quantitative analysis of anti-arrhythmic drugs in human serum and gives rapid feedback in the clinical TDM practices.

Fasting Serum Fructose Levels Are Associated With Risk of Incident Type 2 Diabetes in Middle-Aged and Older Chinese Population.

OBJECTIVE: We investigated the relationship between fasting serum fructose levels and the risk of incident type 2 diabetes in a prospective Chinese cohort. RESEARCH DESIGN AND METHODS: Among 949 community-based participants aged ≥40 years without diabetes at baseline, fasting serum fructose levels were measured using liquid chromatography-tandem mass spectrometry. The participants were followed up for the occurrence of diabetes. Cox regression models were performed to analyze the effect of fasting serum fructose levels on risk of incident diabetes. RESULTS: During a median of 3.5 years' follow-up, 179 of 949 (18.9%) participants developed type 2 diabetes. Elevated fasting serum fructose levels were associated with an increased risk of incident diabetes in a dose-response manner. After adjustment for age, sex, BMI, lipid profiles, blood pressure, liver function, smoking and drinking status, baseline glucose level, and sugar-sweetened beverage consumption, a 1-SD increased fasting fructose level was associated with a 35% (95% CI 1.08-1.67) increased risk of developing diabetes. After further adjustment for serum uric acid and estimated glomerular filtration rate, the association was partially attenuated (hazard ratio 1.33 [95% CI 1.07-1.65]). The association was similar by age, prediabetes status, BMI, and family history of diabetes but attenuated in women (P for heterogeneity = 0.037). CONCLUSIONS: Elevated fasting serum fructose levels were independently associated with increased risk of incident type 2 diabetes in a middle-aged and older Chinese population. Our data suggest that higher fasting serum fructose levels might serve as a biomarker and/or a contributor to incident diabetes.

23,24-Dihydrocucurbitacin B promotes lipid clearance by dual transcriptional regulation of LDLR and PCSK9.

23,24-Dihydrocucurbitacin B (designated as C95 in this article) is a cucurbitane triterpenoid that has been shown to possess a variety of pharmacological activities, such as anti-inflammatory and anti-HIV-1 activities etc. In this study, we investigated the effects of 23,24-dihydrocucurbitacin B on lipid regulation. We showed that 23,24-dihydrocucurbitacin B (1-5 µM) dose-dependently promoted DiI-LDL uptake in HepG2 cells by upregulating low-density lipoprotein receptor (LDLR) protein. In HepG2 cells, 23,24-dihydrocucurbitacin B (1-10 µM) dose-dependently enhanced LDLR promoter activity by elevating the mature form of SREBP2 (sterol regulatory element binding protein 2) protein levels on one hand, and inhibited PCSK9 (proprotein convertase subtilisin/kexin type 9) promoter activity by attenuating HNF1α (hepatocyte nuclear factor-1α) protein levels in nuclei on the other hand. Consequently, the expression of LDLR protein markedly increased, whereas the PCSK9-mediated LDLR protein degradation decreased. In a high-cholesterol LVG golden Syrian Hamster model, administration of 23,24-dihydrocucurbitacin B (30 mg · kg-1⋅ d-1, intragastric, for 3 weeks) significantly decreased the serum LDL-cholesterol (LDL-C) levels. PCSK9 protein levels in the serum and liver tissues were significantly decreased, whereas LDLR protein levels in liver tissues were significantly increased in the treated animals as compared with the control animals. In conclusion, our study demonstrates for the first time that 23,24-dihydrocucurbitacin B exhibits dual transcriptional regulation of LDLR and PCSK9 in HepG2 cells by increasing SREBP2 protein levels and decreasing HNF1α protein levels in the nuclei. These results propose a new strategy to simultaneously manage LDLR and PCSK9 protein expression and provide a promising lead compound for drug development.

Application of a micro plasma collection card for the detection of homocysteine by liquid chromatography with tandem mass spectrometry.

Generally, it is recommended that blood samples for homocysteine detection should be centrifuged immediately to separate plasma in order to avoid continuous synthesis by blood cells. The use of a micro plasma collection card may improve sample stability and result accuracy by offering automatic and instant plasma separation. We compare a micro plasma collection method with routine wet plasma to explore applications of the dried plasma spots for homocysteine determination by using liquid chromatography with tandem mass spectrometry. The method was validated for both dried plasma spots and wet plasma. The assay was linear from 0.5-45 µmol/L with good precisions and accuracies. The extraction recovery and matrix effect for dried plasma spots were >97% and 0.98 after internal standard normalization, respectively. It was reproducible for retaining homocysteine in dried plasma spots and kept stable for 30 days. The plasma conversion factor was 7.77 ± 0.7% by calculating the ratio of homocysteine concentration between dried plasma spots and wet plasma (n = 165). Neither hematocrit nor homocysteine concentration affected the plasma conversion factor as long as the hematocrit was within the normal range. The results support the clinical usefulness of the dried plasma spots as a convenient and stable biological matrix for testing homocysteine.

Oral Bioavailability and Mass Balance Studies of a Novel Anti-arrhythmic Agent Sulcardine Sulfate in Sprague-Dawley Rats and Beagle Dogs.

BACKGROUND AND OBJECTIVES: Sulcardine sulfate is a newly developed candidate drug used to control arrhythmias. The aim of this research was to investigate the pharmacokinetics, bioavailability and excretion characteristics of sulcardine in animals. METHODS: Sprague-Dawley rats were orally and intravenously given sulcardine at 20 and 40 mg/kg. Beagle dogs were also orally and intravenously dosed at 10 mg/kg. Both [3H]-labeled sulcardine and unlabeled sulcardine were given to rats. Feces, urine and bile were collected at 0-72 h for mass balance study. The contents of unlabeled sulcardine and radioactivity in samples were determined by a validated LC-MS/MS method and by liquid scintillation counting, separately. RESULTS: Sulcardine was rapidly eliminated in rats after dosing. The oral bioavailability was 34-35 % in rats, while a higher exposure was observed in dogs (bioavailability = 62.7 %). More than 90 % of dosed sulcardine was recovered, and approximately 20-40 % of the dose excreted into urine as the original form, and the remaining was found in feces and bile, most of which (about 40 %) was transformed into metabolites. No difference was observed between sexes. Metabolism may occur to a large extent after oral administration in rats but to a smaller extent in dogs. CONCLUSIONS: Sulcardine was extensively absorbed in both rats and dogs after oral administration. The mass balance data indicated that sulcardine was widely metabolized in rats after oral administration.

Determination of the novel antiarrhythmic drug sulcardine sulfate in human plasma by liquid chromatography tandem mass spectrometry and its application in a clinical pharmacokinetic study.

Sulcardine sulfate (Sul), a novel antiarrhythmic agent, is currently in phase I and phase II clinical trials. To elucidate its clinical pharmacokinetic characteristics, a rapid and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantification of Sul in human plasma. Plasma samples were precipitated by acetonitrile and isotope-labeled sulcardine was added as internal standard. The analysis was carried out on a Capcell Pak C18 MG III column (100 × 2.0 mm, 5 µm) with 0.1% formic acid in acetonitrile solution and water (17:83, v/v) as mobile phase. The linear range was 5.0-1000 ng/mL for Sul, with a lower limit of quantification of 5.0 ng/mL. The intra- and inter-batch CVs were within ±11.0% and the accuracies were 4.9-107.3%. Our method, for the first time, allows the rapid (only 3.0 min) and accurate quantification of Sul in human plasma. The method has been successfully applied in the pharmacokinetic study of Sul in a clinical trial following oral administration of Sul to healthy volunteers. Copyright © 2016 John Wiley & Sons, Ltd.

Pharmacokinetics of trantinterol and its metabolite in healthy elderly and young subjects.

OBJECTIVE: The aim of this study was to investigate and compare the pharmacokinetics of trantinterol and its active amphoteric carboxylic acid metabolite (1-carbonyl trantinterol) between the healthy elderly and young subjects. METHODS: This was a single-center, open-label, parallel-group study completed by 22 healthy subjects (≥65 years (the elderly group); 18-45 years (the young group); 9 males and 2 females per age group) receiving single oral dose of 50 µg trantinterol tablets. Blood samples were taken at intervals up to 48 hours post-dose. RESULTS: In both groups, maximum plasma concentration of trantinterol was researched at 0.9 hours, while the tmax of 1-carbonyl trantinterol differed slightly. Trantinterol Cmax and AUClast were higher in the elderly group than the young group, by 27% (90% CI, 0.95-1.69) and 77% (90% CI, 1.25-2.51), respectively. For 1-carbonyl trantinterol, Cmax, and AUClast were also higher, by 36% (90% CI, 1.04-1.78) and 71% (90% CI, 1.27-2.30), respectively, in the elderly group. The CL/F and V/F of trantinterol and 1-carbonyl trantinterol were significantly lower in the elderly group, while t1/2 of both did not show significant differences. CL/F of trantinterol and 1-carbonyl trantinterol were found to significantly correlate inversely with age, and positively with the baseline creatinine clearance. CONCLUSIONS: A single dose of 50 µg trantinterol was well tolerated. Significant changes in Cmax and AUC of trantinterol and 1-carbony trantinterol were seen in the elderly and may be clinically important.

Simultaneous Determination of Trantinterol and One of Its Major Metabolites, 1-Carbonyl Trantinterol, in Human Plasma by LC-MS-MS.

A highly selective and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous determination of trantinterol and one of its major metabolites, 1-carbonyl trantinterol, in human plasma. An Oasis MCX 96-well solid-phase extraction cartridge and a SeQuantTM ZIC(®)-HILIC LC column were used for sample preparation and chromatographic separation, respectively. The analytes were monitored by a QTrap 5500 mass spectrometer with positive electrospray ionization. Multiple reaction monitoring was used for quantification using the precursor to product ion pairs of m/z 311.1 → 237.9 (trantinterol), m/z 325.1 → 251.9 (1-carbonyl trantinterol) and m/z 368.4 → 294.0 (bambuterol as internal standard). The assay had a calibration range from 0.2 to 50 pg/mL and a lower limit of quantification of 0.2 pg/mL for both trantinterol and 1-carbonyl trantinterol. The inter-day and intra-day precisions were <12.0% and the accuracies were within the range of 87.1-111%. The mean recovery ranged from 82.0 to 97.7% and internal standard normalized matrix effect from 0.813 to 0.899. The analytes were stable under all tested conditions. This validated method was successfully applied to a pilot pharmacokinetic study in healthy subjects administered a single 50 µg oral dose.

Hair analysis, a reliable and non-invasive method to evaluate the contamination by clenbuterol.

The illegal use of clenbuterol has been an increasingly serious issue in today's livestock products industry. It becomes an important project to develop a reliable approach to detect its content in food animals. A simple and sensitive LC-MS/MS method was developed to detect clenbuterol residue in hair, with the low limit of quantitation (LLOQ) about 0.5ng/g. Hogs fed with 340µg/day of clenbuterol for 2 weeks were found a high clenbuterol residue in their hair approximately at 1-2 months after withdrawal. There remained 3.31ng/g clenbuterol in hog hair approximately 5 months after the last administration, focused on the tip of the hair (mainly in hogs with dark hair). An extensive contamination was observed in twenty investigated market hogs whose dark hair obviously had a higher clenbuterol residue than the light ones (p=0.017, t test). Volunteers (60.3 percent) from Xuhui district (Shanghai) were found to have a detectable amount of clenbuterol in their hair (>0.5ng/g). In conclusion, hair residue detection is a reliable method to evaluate the clenbuterol contamination in animals and humans. Meat supply in the Xuhui district might have serious potential safety risks which should be further investigated and discussed to determine the safety range of clenbuterol residue.

Hyperlipidemia and atherosclerotic lesion development in Ldlr-deficient mice on a long-term high-fat diet.

BACKGROUND: Mice deficient in the LDL receptor (Ldlr(-/-) mice) have been widely used as a model to mimic human atherosclerosis. However, the time-course of atherosclerotic lesion development and distribution of lesions at specific time-points are yet to be established. The current study sought to determine the progression and distribution of lesions in Ldlr(-/-) mice. METHODOLOGY/PRINCIPAL FINDINGS: Ldlr-deficient mice fed regular chow or a high-fat (HF) diet for 0.5 to 12 months were analyzed for atherosclerotic lesions with en face and cross-sectional imaging. Mice displayed significant individual differences in lesion development when fed a chow diet, whereas those on a HF diet developed lesions in a time-dependent and site-selective manner. Specifically, mice subjected to the HF diet showed slight atherosclerotic lesions distributed exclusively in the aortic roots or innominate artery before 3 months. Lesions extended to the thoracic aorta at 6 months and abdominal aorta at 9 months. Cross-sectional analysis revealed the presence of advanced lesions in the aortic sinus after 3 months in the group on the HF diet and in the innominate artery at 6 to 9 months. The HF diet additionally resulted in increased total cholesterol, LDL, glucose, and HBA1c levels, along with the complication of obesity. CONCLUSIONS/SIGNIFICANCE: Ldlr-deficient mice on the HF diet tend to develop site-selective and size-specific atherosclerotic lesions over time. The current study should provide information on diet induction or drug intervention times and facilitate estimation of the appropriate locations of atherosclerotic lesions in Ldlr(-/-) mice.

Contribution of carboxylesterase in hamster to the intestinal first-pass loss and low bioavailability of ethyl piperate, an effective lipid-lowering drug candidate.

Ethyl piperate is an effective lipid-lowering drug candidate synthesized from piperine. However, its pharmacokinetic characteristics and oral absorption process remain unclear. A liquid chromatography-tandem mass spectrometry method was applied to determine the oral bioavailability of ethyl piperate. Simulated gastrointestinal pH conditions and intestinal washings were prepared to investigate their contributions to the loss of ethyl piperate. Hydrolysis by carboxylesterase (CES) was evaluated in vitro using microsomes and S9 fractions. In situ intestinal single-pass perfusion experiments were performed to estimate the role of CES in ethyl piperate absorption. The bioavailability of ethyl piperate was extremely low (0.47%) in hamster independent of gastrointestinal environmental effects. Ethyl piperate was a typical substrate of CES with kinetic parameters K(m) and V(max) of 7.56 ± 1.491 µM and 0.16 ± 0.008 nmol · min(-1) · mg protein(-1), respectively. CES was responsible for 85.8% of the intestinal hydrolysis of ethyl piperate. Specific inhibition of CES with bis-p-nitrophenyl phosphate (BNPP), decreased degradation clearance to 36% of control with no significant change in absorption clearance. This contrasted with the results of Caco-2 monolayer experiments, which showed a dramatic increase in the apparent permeability coefficient after BNPP treatment. mRNA levels for the CES isozyme, CES2A3, were similar among the three regions of hamster intestine and 60% less than those in liver; CES1B1 mRNA levels were even lower in the intestine and showed a proximal-to-distal decrease. In conclusion, CES markedly contributes to intestinal first-pass hydrolysis of ethyl piperate that is sufficient, but not necessary, to cause the observed extremely low bioavailability.

Pharmacokinetics of depside salts from Salvia miltiorrhiza in healthy Chinese volunteers: A randomized, open-label, single-dose study.

BACKGROUND: Depside salts from Salvia miltiorrhiza, with active components of lithospermic acid B (LSB), rosmarinic acid (RA), and lithospermic acid (LA), are a multicomponent drug marketed in China for the treatment of coronary heart disease. OBJECTIVES: The aims of this study were to determine the concentrations of LSB, RA, and LA in human plasma and urine, and to compare the pharmacokinetic properties of depside salts from S miltiorrhiza in healthy Chinese volunteers. METHODS: A randomized, open-label, single-dose study was conducted in healthy Chinese volunteers. Participants were randomly assigned to receive a single intravenous infusion of 100 or 200 mg of depside salts from S miltiorrhiza. Blood was collected through a venous cannula prior to study drug administration (0 min) and at 10, 20, 30, 60, 65, 70, 80, and 90 minutes and 2, 3, 4, 6, 8, 12, and 24 hours after study drug administration. Urine samples were taken before study drug administration (0) and at 0 to 12 and 12 to 24 hours after study drug administration. LSB, RA, and LA concentrations in serum and urine were analyzed by an LC-MS/MS method. Tolerability was determined by clinical assessment; vital signs (ie, blood pressure, heart rate, breathing rate, body temperature) monitoring at baseline and at the end of the study, clinical laboratory tests (ie, hematology, blood biochemistry, hepatic function, renal function, urinalysis), 12-lead ECG measurements, and physical examinations at baseline and after completion of the study. RESULTS: Twelve Chinese volunteers (6 males, 6 females; mean [SD] age, 25.2 [3.8] years; mean height, 165.7 [8.9] cm; mean body mass index, 21.6 [2.5] kg/m(2)) were enrolled in the study. Peak plasma concentrations of LSB, RA and LA were observed at 0.3 to 1 hour following the 1-hour intravenous infusion, with respective mean (SD) Cmax of 4925 (1861), 174 (61), and 361 (101) ng/mL for the 100-mg dose and 10,285 (2259), 308 (77), and 674 (85) ng/mL for the 200-mg dose. The AUClast values for LSB, RA, and LA were 4537 (1265), 129 (28), and 1229 (330) ng/mL/h, respectively, for the 100-mg dose and 10,426 (2589), 260 (53), and 2792 (729) ng/mL/h for the 200-mg dose. No significant difference in pharmacokinetic parameters was observed between male and female subjects. Three metabolites were found in the plasma with low concentrations. The urinary excretion recoveries of LSB, RA, and LA were 0.58% (0.42%), 25.21% (20.61%), and 10.02% (7.72%) for the 100-mg dose and 0.38% (0.18%), 20.11% (10.50%), and 6.34% (3.20%) for the 200-mg dose. No adverse events were reported by the subjects or found by the investigators in the analysis of vital signs, 12-lead ECG measurements, physical examinations, or clinical laboratory tests. CONCLUSIONS: Following single intravenous infusion of 100 or 200 mg of depside salts from S miltiorrhiza to healthy Chinese subjects, no statistical differences in pharmacokinetic parameters were observed between males and females. The 2 doses of depside salts from S miltiorrhiza were clinically well tolerated during the study.

Liquid chromatography/tandem mass spectrometry for the determination of changrolin in rat plasma: application to a bioavailability study.

A sensitive and specific LC-CMS/MS method was developed for the quantification of changrolin, an anti-arrhythmic drug, in rat plasma using tiapride as internal standard. Liquid-liquid extraction was employed for sample preparation and analyzed using a multiple reaction monitoring mode with electrospray positive ionization source. The calibration curve for changrolin was linear over the range 5-1600 ng/mL with coefficients of correlation >0.99. The intra- and inter-batch precision was less than 8.6%, and accuracy ranged from 94.6% to 104.5%. This validated LC-MS/MS method was successfully applied to a bioavailability study of oral and intravenous administration of changrolin with 20mg/kg dosage in SD rats.