Simultaneous determination and determination of sildenafil and its active metabolite in human plasma using LC-MS/MS method.

A sensitive and selective high-performance liquid chromatography-tandam mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantification of sildenafil and its metabolite N-desmethyl sildenafil in human plasma. Sildenafil-d8 was used as an internal standard. The analytes were extracted by precipitation extraction and chromatographed on a C18 column using mobile phase A of water (containing 0.1% formic acid) and mobile phase B of acetonitrile (containing 0.1% formic acid) with gradient elution. Quantification was done using multiple reaction monitoring mode to monitor the precursor-to-product ion transitions of m/z 475.4 → m/z 283.3 for sildenafil, m/z 461.4 → m/z 283.2 for N-desmethyl sildenafil and m/z 483.3 → m/z 108.1 for IS in positive ionization mode. The calibration curve was established over the range of 2.00-1,000 ng/ml and the correlation coefficient was >0.99. The intra-day and inter-day relative standard deviations were <6.5% for sildenafil and 6.3% for N-desmethyl sildenafil respectively. Accuracy determinaed at four concentrations was 86.50-105.67% for sildenafil and 96.83-114.40% for N-desmethyl sildenafil. This method was successfully applied to a pharmacokinetic description of sildenafil and the effect of food intake on the pharmacokinetics of sildenafil was also demonstrated in healthy Chinese volunteers.

An improved LC-MS/MS method for determination of cinacalcet in human plasma and its application to the evaluation of food intake effect on the pharmacokinetics of cinacalcet in healthy volunteers.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of cinacalcet in human plasma was developed and validated. This assay was based on liquid-liquid extraction and cinacalcet-d4 was used as an internal standard (IS). Separation was achieved on a C18 column by the mobile phase A of water (containing 0.1% formic acid) and the mobile phase B of acetonitrile-water (95:5, v/v) (containing 0.2% formic acid) with gradient elution. Quantification was done using multiple reaction monitoring mode to monitor the precursor-to-product ion transitions of m/z 358.2 → m/z 155.2 for cinacalcet and m/z 362.3 → m/z 155.0 for IS at positive ionization mode. The calibration curve was established over the range 0.05-20.0 ng/mL and the correlation coefficient was >0.99. The intra- and inter-day relative standard deviations were <5.8%. Accuracy determined at four concentrations ranged between 96.0 and 106.0%. This method was successfully applied to a pharmacokinetic description of oral dose of cinacalcet and the significant effect of food intake on the pharmacokinetics of cinacalcet was first demonstrated in Chinese healthy volunteers.

Acute administration of tumour necrosis factor-α induces spontaneous calcium release via the reactive oxygen species pathway in atrial myocytes.

Aims: The arrhythmogenic mechanisms of atrial fibrillation (AF) that are induced by acute inflammation, such as postoperative AF, are not well understood. We investigated the acute effects of tumour necrosis factor-α (TNF-α) that mimic acute inflammation on Ca2+ handling in isolated atrial myocytes and its underlying mechanisms. Methods and results: Cytosol Ca2+ handling and mitochondrial reactive oxygen species (ROS) production were studied in freshly isolated atrial myocytes of wild-type mice that were exposed to TNF-α (0.05 ng/mL) for 2 h by Ionoptix and confocal microscopy. The acute effects of TNF-α on Ca2+ handling were decreased amplitudes and prolonged decay times of Ca2+ transients in isolated atrial myocytes. A significant reduction in the sarcoplasmic reticulum (SR) Ca2+ content was detected in TNF-α treated cells, which was associated with increased spontaneous Ca2+ release events. In particular, physiological concentrations of TNF-α dramatically promoted the frequency of spontaneous Ca2+ waves and Ca2+ sparks, while the spark mass presented with reduced amplitudes and prolonged durations. The underlying mechanisms of pro-arrhythmic effects of TNF-α were further investigated. Acute exposure to TNF-α rapidly promoted mitochondrial ROS production that was correlated with the acute effect of TNF-α on Ca2+ handling, and enhanced the oxidation of calcium/calmodulin-dependent protein kinase II (CaMKII) and the phosphorylation of RyR2. However, the performance of ROS inhibitor, DL-Dithiothreitol (DTT), reversed Ca2+ handling disorders induced by TNF-α. Conclusion: Tumour necrosis factor-α rapidly increases spontaneous Ca2+ release and promotes atrial arrhythmogenesis via the ROS pathway, which suggests that antioxidant therapy is a promising strategy for acute inflammation related AF.

Research on aeromagnetic data error analysis and processing of multi-rotor UAV based on variational mode decomposition algorithm.

Aeromagnetic survey of multi-rotor UAV is widely used in small and medium-sized mineral resources survey, engineering investigation, non-explosive detection and other fields due to its advantages of high safety, low cost and convenient operation. The original data of UAV aeromagnetic survey includes interference from external environment, interference from UAV platform and interference from airborne electromagnetic equipment. The interference is mainly shown as striping anomaly along the direction of the survey line in the aeromagnetic anomaly map, which affects the accuracy of aeromagnetic compensation and information detection of geological anomaly body, thus affecting the accuracy of interpretation of geological anomaly body. In this paper, the algorithm of Variational Modal Decomposition (VMD) is introduced to filter and preprocess the aeromagnetic data to obtain high quality aeromagnetic data. At the same time, the source and characteristics of the errors are predicted according to the interference size and spectrum characteristics of the Modal function errors, which provides a reference for the optimization of aeromagnetic system.

Modifications of the Langendorff Method for Simultaneous Isolation of Atrial and Ventricular Myocytes from Adult Mice.

A single cardiomyocyte is a vital tool in the cellular and subcellular level studies of cardiac biology and diseases as a fundamental unit of contraction and electrical activity. Hence, isolating viable, high-quality cardiomyocytes from the heart is the initial and most crucial experimental step. Comparing the various protocols for isolating the cardiomyocytes of adult mice, the Langendorff retrograde perfusion is the most successful and reproducible method reported in the literature, especially for isolating ventricular myocytes. However, isolating quality atrial myocytes from the perfused heart remains challenging, and few successful isolation reports are available. Solving this complicated problem is extremely important because apart from ventricular disease, atrial disease accounts for a large part of heart diseases. Therefore, further investigations on the cellular level to reveal the mechanisms are warranted. In this paper, a protocol based on the Langendorff retrograde perfusion method is introduced and some modifications in the depth of aorta cannulation and the steps that may affect the digestion process to isolate atrial and ventricular myocytes were simultaneously made. Moreover, the isolated cardiomyocytes are confirmed to be amenable to patch clamp investigation.

The Association of New-Onset Atrial Fibrillation and Risk of Cancer: A Systematic Review and Meta-Analysis.

BACKGROUND: There are distinct results for the relationship between new-onset atrial fibrillation (NOAF) and subsequent incident cancer. To date, no systematic analysis has been conducted on this issue. This study aims to explore the relationship between NOAF and the risk of developing cancer through a meta-analysis with a large sample size. METHODS: Electronic databases, such as PubMed and EMBASE, were searched for published relevant studies on NOAF patients diagnosed with cancer after and during follow-ups, including reported records of baseline information and the statistical result of morbidity. Two investigators independently reviewed the articles and extracted the data using uniform standards and definitions. The meta-analysis was conducted using the Cochrane Program Review Manager. RESULTS: This meta-analysis consisted of five cohort studies and one case-control study, which comprised 533,514 participants. The pooled relative risk (RR) for incident cancer was 1.24 (95% CI: 1.10-1.39, P=0.0003). The temporal trend analysis demonstrated that an increased risk of cancer was observed during the initial 90 days (RR: 3.44, 95% CI: 2.29-5.57, P < 0.00001), but not after that. Lung cancer (RR: 1.51, 95% CI: 1.47-1.55, P < 0.00001) was associated with NOAF, but not colorectal cancer and breast cancer. CONCLUSION: This meta-analysis provides evidence that NOAF is associated with increased risk of cancer. The risk of incident cancer particularly increases within 90 days after NOAF diagnosis, but not after that.

Molecular cloning and function analysis of an anthocyanidin synthase gene from Ginkgo biloba, and its expression in abiotic stress responses.

Anthocyanidin synthase (ANS, leucoanthocyanidin oxygenase), a 2-oxoglutarate iron-dependent oxygenase, catalyzed the penultimate step in the biosynthesis of the anthocyanin class of flavonoids, from the colorless leucoanthocyanidins to the colored anthocyanidins. The full-length cDNA and genomic DNA sequences of ANS gene (designated as GbANS) were isolated from Ginkgo biloba for the first time. The full-length cDNA of GbANS contained a 1062-bp open reading frame (ORF) encoding a 354-amino-acid protein. The genomic DNA analysis showed that GbANS gene had three exons and two introns. The deduced GbANS protein showed high identities to other plant ANSs. The conserved amino acids (H-X-D) ligating ferrous iron and residues (R-X-S) participating in 2-oxoglutarate binding were found in GbANS at the similar positions like other ANSs. Southern blot analysis indicated that GbANS belonged to a multi-gene family. The expression analysis by real-time PCR showed that GbANS expressed in a tissue-specific manner in G. biloba. GbANS was also found to be up-regulated by all of the six tested abiotic stresses, UV-B, abscisic acid, sucrose, salicylic acid, cold and ethylene, consistent with the promoter region analysis of GbANS. The recombinant protein was successfully expressed in E. coli strain with pET28a vector. The in vitro enzyme activity assay by HPLC indicated that recombinant GbANS protein could catalyze the formation the cyanidin from leucocyanidin and conversion of dihydroquercetin to quercetin, suggesting GbANS is a bifunctional enzyme within the anthocyanidin and flavonol biosynthetic pathway.

Electroacupuncture Stimulation of Language-Implicated Acupoint Tongli (HT 5) in Healthy Subjects: An fMRI Evaluation Study.

OBJECTIVE: To explore brain activations associated with electroacupuncture simulation at Tongli (HT 5) and its comparison with brain activations during picture-naming task. METHODS: Twenty healthy subjects were enrolled in this study. Half of them received electroacupuncture stimulation at HT 5 (ACUP group) and the other half of them received stimulation at a nonmeridian sham acupoint (SHAM group). All subjects performed picture-naming task. Each subject finished two runs of functional magnetic resonance imaging examinations in one session and picture-naming task was performed before electroacupuncture stimulation. Subjective brain activations were obtained using generalized linear model and inter-group analyses were performed after that. RESULTS: The electroacupuncture stimulation at HT 5 induced significant brain activations in both the anterior and posterior language regions, including the left inferior frontal gyrus, which was in consistent with activations induced during picture-naming task. Group analysis showed a tendency of increased activation of ACUP group in left inferior frontal gyrus compared with SHAM group (P<0.05 FDR corrected). CONCLUSIONS: Electroacupuncture treatment at the acupoint HT 5 has modulation effect on typical language-implicated brain regions in healthy subjects, which provides supporting evidence for beneficial effects of needling at HT 5 for recovery of language function in aphasia.