Determination of free and total warfarin concentrations in plasma using UPLC MS/MS and its application to a patient samples

Warfarin is routinely monitored by assessing its pharmacologic effects on the international normalized ratio. However, having a patient with INR not responding to increasing warfarin dose mandates a direct measurement of warfarin concentrations (total and free) for better patient clinical management of warfarin therapy. Therefore, a new fully validated specific, precise and accurate ultra-performance liquid chromatography tandem mass spectrometry was developed for the determination of free and total warfarin in human plasma. Free warfarin was measured in plasma filtrate, prepared by ultrafiltration, and sample pretreatment involved protein precipitation with acetonitrile. Linear response (r(2) ≥0.99) was observed over the studied range of free and total warfarin, with the lower limit of detection of 0.25 ng/mL. The intra- and inter-day precision (relative standard deviation) values were <10% and the accuracy (relative error) was ≤6.6 for free and total warfarin. There was no significant difference (p>0.05) between inter- and intra-day studies for the free and total warfarin, which confirmed the reproducibility of the assay method. The mean extraction efficiency was 88.6-107.2% of free and total warfarin. The assay was sensitive to follow warfarin pharmacokinetics (free and total) in a patient with resistance to warfarin up to 24 h after a daily dose of warfarin.     

Unexpected o → n migration of the methyl group in 5-methoxy-6-cyanobenzimidazo-[1,2-a][1,8]naphthyridine

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 273–274, February, 1989.     

Author Correction: Drier Climatic Conditions Increase Withanolide Content of Withania coagulans Enhancing its Inhibitory Potential against Human Prostate Cancer Cells

Applied Biochemistry and Biotechnology - The original version of this article unfortunately contained a mistake in the image of Figure 1&nbsp;and in Table 4. The corrected version of the figure...     

Aqueous single step synthesis and structural characterization of allylated,propargylated, and benzylated 3-substituted 3-aminooxindoles

Efficient zinc-mediated allylation, propargylation, and benzylation of isatin-derived imines were undertaken for the synthesis of 3-substituted 3-aminooxindoles with ≈80% yield. Such alternative approach has efficiently avoided the use of catalysts, severe reaction conditions, multistep procedures, and reaction additives. For exploring and materializing the synthetic utility, different allyl, propargyl, and benzyl bromides were used for generalizing the synthetic route. The structure of the synthesized compounds was established and confirmed by ¹H NMR, ¹³C NMR, FTIR, and mass spectroscopic techniques.     

Inhibitory effects of phylligenin and quebrachitol isolated from Mitrephora vulpina on platelet activating factor receptor binding and platelet aggregation

Phylligenine, together with quebrachitol, stigmasterol and two aporphine alkaloids--oxoputerine and liriodenine--were isolated from the twigs of Mitrephora vulpina C.E.C. Fisch. They were evaluated for their ability to inhibit platelet activating factor (PAF) receptor binding to rabbit platelets using 3H-PAF as a ligand and their antiplatelet aggregation effect in human whole blood induced by arachidonic acid (AA), collagen and adenosine diphosphate (ADP). Of all the compounds tested, phylligenin and quebrachitol exhibited potent and concentration-dependent inhibitory effects on PAF receptor binding, with IC(50) values of 13.1 and 42.2 μM, respectively. The IC(50) value of phylligenin was comparable to that of cedrol (10.2 μM), a potent PAF antagonist. Phylligenin also showed strong dose-dependent inhibitory activity on platelet aggregation induced by AA and ADP.     

Efficient delivery of Cre-recombinase to neurons in vivo and stable transduction of neurons using adeno-associated and lentiviral vectors

Background

As development proceeds the human embryo attains an ever more complex three dimensional (3D) structure. Analyzing the gene expression patterns that underlie these changes and interpreting their significance depends on identifying the anatomical structures to which they map and following these patterns in developing 3D structures over time. The difficulty of this task greatly increases as more gene expression patterns are added, particularly in organs with complex 3D structures such as the brain. Optical Projection Tomography (OPT) is a new technology which has been developed for rapidly generating digital 3D models of intact specimens. We have assessed the resolution of unstained neuronal structures within a Carnegie Stage (CS)17 OPT model and tested its use as a framework onto which anatomical structures can be defined and gene expression data mapped.

Results

Resolution of the OPT models was assessed by comparison of digital sections with physical sections stained, either with haematoxylin and eosin (H&E) or by immunocytochemistry for GAP43 or PAX6, to identify specific anatomical features. Despite the 3D models being of unstained tissue, peripheral nervous system structures from the trigeminal ganglion (~300 μm by ~150 μm) to the rootlets of cranial nerve XII (~20 μm in diameter) were clearly identifiable, as were structures in the developing neural tube such as the zona limitans intrathalamica (core is ~30 μm thick). Fourteen anatomical domains have been identified and visualised within the CS17 model. Two 3D gene expression domains, known to be defined by Pax6 expression in the mouse, were clearly visible when PAX6 data from 2D sections were mapped to the CS17 model. The feasibility of applying the OPT technology to all stages from CS12 to CS23, which encompasses the major period of organogenesis for the human developing central nervous system, was successfully demonstrated.

Conclusion

In the CS17 model considerable detail is visible within the developing nervous system at a minimum resolution of ~20 μm and 3D anatomical and gene expression domains can be defined and visualised successfully. The OPT models and accompanying technologies for manipulating them provide a powerful approach to visualising and analysing gene expression and morphology during early human brain development.     

Spectroscopic elucidation of pseudo-base formation from benzo[8,9]quinoliziono[4,5,6,7-fed]phenanthrindyliums

¹³C and ¹H NMR spectra and UV spectra are recorded and assigned for a variety of substituted and hetero derivatives of benzo[8,9]quinolizino[4,5,6,7-fed]phenanthrindyliums. Large specific effects of traces of water on these spectra are traced to pseudo-base formation.     

Multivalent Siderophore–DOTAM Conjugates as Theranostics for Imaging and Treatment of Bacterial Infections

There is a strong need to better diagnose infections at deep body sites through noninvasive molecular imaging methods. Herein, we describe the synthesis and characterization of probes based on siderophore conjugates with catechol moieties and a central DOTAM scaffold. The probes can accommodate a metal ion as well as an antibiotic moiety and are therefore suited for theranostic purposes. The translocation of the conjugates across the outer and inner cell membranes of E. coli was confirmed by growth recovery experiments with enterobactin-deficient strains, by the antibacterial activity of ampicillin conjugates, and by confocal imaging using a fluorogen-activating protein–malachite green system adapted to E. coli. The suitability of the probes for in vivo imaging was demonstrated with a Cy5.5 conjugate in mice infected with P. aeruginosa.