Chromatographic separation and sensitive determination of teriflunomide,an active metabolite of leflunomide in human plasma by liquid chromatography-tandem mass spectrometry

A sensitive, selective and high throughput liquid chromatography tandem mass spectrometry (LC–ESI-MS/MS) method has been developed for the determination of teriflunomide, an active metabolite of leflunomide in human plasma. Plasma samples were prepared by liquid–liquid extraction of teriflunomide and valsartan as internal standard (IS) in ethyl acetate from 200 μL human plasma. The chromatographic separation was achieved on an Inertsil ODS-3 C18 (50 mm × 4.6 mm, 3 μm) analytical column using isocratic mobile phase, consisting of 20 mM ammonium acetate–methanol (25:75, v/v), at a flow-rate of 0.8 mL/min. The precursor → product ion transition for teriflunomide (m/z 269.0 → 82.0) and IS (m/z 434.1 → 350.3) were monitored on a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring (MRM) and negative ion mode. The method was validated over a wide dynamic concentration range of 10.1–4001 ng/mL. Matrix effect was assessed by post-column infusion experiment and the mean process efficiency were 91.7% and 88.2% for teriflunomide and IS respectively. The method was rugged and rapid with a total run time of 2.0 min and is applied to a bioequivalence study of 20 mg leflunomide (test and reference) tablet formulation in 12 healthy Indian male subjects under fasting condition.     

Processes Linking Religious Involvement and Telomere Length

Although numerous studies suggest that religious involvement is associated with better health and longer life expectancies, it is unclear whether these general patterns extend to cellular aging. The mechanisms linking indicators of religious involvement with indicators of cellular aging are also undefined. We employed longitudinal data from the 2004 and 2008 Health and Retirement Study, a national probability sample of Americans aged 50 and older, to test whether average telomere length varied according to level of religious attendance. We also tested several potential mechanisms. Our results showed that respondents who attended religious services more frequently in 2004 also exhibited fewer stressful events, lower rates of smoking, fewer symptoms of depression, and lower levels of C-reactive protein in 2008. Respondents who increased their level of attendance from 2004 to 2008 also exhibited lower rates of smoking in 2008. Although religious attendance was not directly associated with telomere length, our mediation analyses revealed significant indirect effects through depression and smoking, but not stressful events or C-reactive protein. We conclude that religious attendance may promote telomere length indirectly by reducing symptoms of depression and the risk of smoking. There was no evidence to support stressful events or C-reactive protein as mechanisms of religious attendance.     

A mechanistic basis for amplification differences between samples and between genome regions

ABSTRACT: BACKGROUND: For many analytical methods the efficiency of DNA amplification varies across the genome and between samples. The most affected genome regions tend to correlate with high C + G content, however this relationship is complex and does not explain why the direction and magnitude of effects varies considerably between samples. RESULTS: Here, we provide evidence that sequence elements that are particularly high in C + G content can remain annealed even when aggressive melting conditions are applied. In turn, this behavior creates broader 'Thermodynamically Ultra-Fastened' (TUF) regions characterized by incomplete denaturation of the two DNA strands, so reducing amplification efficiency throughout these domains. CONCLUSIONS: This model provides a mechanistic explanation for why some genome regions are particularly difficult to amplify and assay in many procedures, and importantly it also explains inter-sample variability of this behavior. That is, DNA samples of varying quality will carry more or fewer nicks and breaks, and hence their intact TUF regions will have different lengths and so be differentially affected by this amplification suppression mechanism -- with 'higher' quality DNAs being the most vulnerable. A major practical consequence of this is that inter-region and inter-sample variability can be largely overcome by employing routine fragmentation methods (e.g. sonication or restriction enzyme digestion) prior to sample amplification.     

First Report: Trace Fossil Assemblage Ptychoplasma (P. excelsum,P. vagans), Dendroidichnites (D. irregulare), Ctenopholeus (?C. kutcheri) and Bergaueria (B. hemispherica) in the Cretaceous Rocks of Bagh Formation,Mainland Gujarat,India

Abstract

This report documents the discovery of repichnia trace fossils Ptychoplasma (P. excelsum and P. vagans) and Dendroidichnites (D. irregulare); the fodichnia traces ?Ctenopholeus (?C. kutcheri) and cubichnia traces Bergaueria (B. hemishperica) from silty limestones of the Cretaceous Bagh Formation. These trace fossils have significant implications for the depositional facies and the paleo-environmental interpretations of the Bagh Formation, which have long been debated. Previously identified traces of Protovirgularia were also found in association with the newly discovered trace fossils, indicating the coexistence of both wedge and cleft-foot bivalves. The western area of the mainland Gujarat is known for its abundance and diversity of trace fossils. The trace fossil bearing Cretaceous rocks in the region occur as thin irregular detached patches and linear outcrops. Previous studies documenting trace fossil assemblages from the Bagh Formation characterised them as a combination of dwelling, feeding and locomotion forms, with the stratigraphic unit becoming less fossiliferous westward. Trace fossils in this formation have been studied and described by many workers in the surrounding areas; however, ichnofossils described in this study are new to the Bagh Formation in this area. These trace fossils were observed on recently exposed outcrops along road cuts associated with new road construction from Khasra to Mogra village around Kadipani in Mainland Gujarat.