In silico and in vitro approaches to develop Dimethylarginine dimethylaminohydrolase-1 inhibitors

Introduction: Dimethylarginine dimethylaminohydrolases (DDAH) metabolise the endogenous nitric oxide synthase (NOS) inhibitors: asymmetric dimethylarginine (ADMA) and monomethylarginine1. In sepsis excessive nitric oxide partially contributes to acute circulatory failure, and pharmacological DDAH1 inhibition has been proposed in order to increase methylarginines and reduce NO levels 2. The SR257 arginine analogue, with NG-methoxyethyl substituent, inhibits DDAH1 with an IC50 22 µM without directly inhibiting NOSs1,3. Methods: Acyclic and cyclic NG,NG-disubstituted arginines were made as previously described4 using Katritzky’s synthesis preparing trisubstituted guanidines from di-(benzotriazol-1-yl)methanimine5. Molecular docking was employed to explore interactions of these NG,NG-disubstituted arginines with human DDAH1 (PDB 2JAJ) using Glide (Schroedinger6) and Autodock47. The published SR257 ligand was used to define the binding site with both software tools. Recombinant human DDAH1 activity was measured using colorometric citrulline assay8 containing ADMA (100 µM), sodium phosphate (10 mM pH7.4); with symmetric dimethylarginine (100 µM), not a substrate for DDAH1, as blank. Experiments were carried out in duplicate, and repeated on at least 3 separate occasions. Results: Recombinant DDAH1 activity was reduced to less than 25% of control (ADMA substrate, 100 µM) in the presence of 100 µM piperidinyl, methoxyethyl/methyl, N-methylpiperazinyl, with morpholinyl and pyrrolidinyl substituents reducing activity to less than 10% of control. The in silico Glide docking score and predicted Autodock4 binding energy for human DDAH1 (PDB, 2JAJ) for the known SR257 DDAH1 inhibitor and NG,NG-disubstituted arginines are shown in the table: Conclusion: Both Autodock4 and Glide docking predicted higher binding energies for morpholinyl, pyrrolidinyl and piperinyl than the known SR257 compound. In vitro assays confirmed these NG,NG-disubstituted arginines reduced DDAH1 activity. There was variation between Glide and Autodock4 in the docking predictions for methoxyethyl/methyl and N-methylpiperazinyl. In silico prediction of DDAH1-ligand interactions may assist in the future design and development of novel NG,NG-disubstituted arginines. References: 1 Leiper, J. et al. (2007) Nat Med. 13:198-203. 2 Wang, Z et al. (2014) Biochem J. 460:309 3 Rossiter, S. et al. (2005) J Med Chem. 48:4670-4678. 4 Morfill, C et al. (2012) http://www.pA2online.org/abstracts/Vol10Issue4abst197P.pdf 5 Katritzky, A et al. (2000) J. Org. Chem. 65: 8080-8082. 6 Friesner, RA et al. (2006) J Med Chem. 49:6177-6196. 7 Morris, GM et al. (2009) J. Comp. Chem. 16:2785-91. 8 Knipp, M & Vasak, M (2000) Anal Biochem 286:257-64

Fatigue detection using computer vision

Long duration driving is a significant cause of fatigue related accidents of cars, airplanes, trains and other means of transport. This paper presents a design of a detection system which can be used to detect fatigue in drivers. The system is based on computer vision with main focus on eye blink rate. We propose an algorithm for eye detection that is conducted through a process of extracting the face image from the video image followed by evaluating the eye region and then eventually detecting the iris of the eye using the binary image. The advantage of this system is that the algorithm works without any constraint of the background as the face is detected using a skin segmentation technique. The detection performance of this system was tested using video images which were recorded under laboratory conditions. The applicability of the system is discussed in light of fatigue detection for drivers

The spin axes orbital alignment of both stars within the eclipsing binary system V1143Cyg using the Rossiter-McLaughlin effect

Context: The Rossiter-McLaughlin (RM) effect, a rotational effect in eclipsing systems, provides unique insight into the relative orientation of stellar spin axes and orbital axes of eclipsing binary systems. Aims: Our aim is to develop a robust method to analyze the RM effect in an eclipsing system with two nearly equally bright components. This gives access to the orientation of the stellar rotation axes and may shed light on questions of binary formation and evolution. Methods: High-resolution spectra have been obtained both out of eclipse and during the primary and secondary eclipses in the V1143Cyg system, using the high-resolution Hamilton Echelle Spectrograph at the Lick Observatory. The Rossiter-McLaughlin effect is analyzed in two ways: (1) by measuring the shift of the line center of gravity during different phases of the eclipses and (2) by analysis of the line shape change of the rotational broadening function during eclipses. Results: The projected axes of both stars are aligned with the orbital spin within the observational uncertainties, with the angle of the primary rotation axis beta_p=0.3+-1.5 deg, and the angle of the secondary rotation axis beta_s=-1.2+-1.6 deg, thereby showing that the remaining difference between the theoretical and observed apsidal motion for this system is not due to a misalignment of the stellar rotation axes. Both methods utilized in this paper work very well, even at times when the broadening profiles of the two stars overlap.[abridged]Comment: Accepted for publication in A&A; 11 pages, 9 figures, 3 tables ; a typo in the abstract has been correcte

Movement-related beta oscillations show high intra-individual reliability

Oscillatory activity in the beta frequency range (15-30Hz) recorded from human sensorimotor cortex is of increasing interest as a putative biomarker of motor system function and dysfunction. Despite its increasing use in basic and clinical research, surprisingly little is known about the test-retest reliability of spectral power and peak frequency measures of beta oscillatory signals from sensorimotor cortex. Establishing that these beta measures are stable over time in healthy populations is a necessary precursor to their use in the clinic. Here, we used scalp electroencephalography (EEG) to evaluate intra-individual reliability of beta-band oscillations over six sessions, focusing on changes in beta activity during movement (Movement-Related Beta Desynchronization, MRBD) and after movement termination (Post-Movement Beta Rebound, PMBR). Subjects performed visually-cued unimanual wrist flexion and extension. We assessed Intraclass Correlation Coefficients (ICC) and between-session correlations for spectral power and peak frequency measures of movement-related and resting beta activity. Movement-related and resting beta power from both sensorimotor cortices was highly reliable across sessions. Resting beta power yielded highest reliability (average ICC=0.903), followed by MRBD (average ICC=0.886) and PMBR (average ICC=0.663). Notably, peak frequency measures yielded lower ICC values compared to the assessment of spectral power, particularly for movement-related beta activity (ICC=0.386-0.402). Our data highlight that power measures of movement-related beta oscillations are highly reliable, while corresponding peak frequency measures show greater intra-individual variability across sessions. Importantly, our finding that beta power estimates show high intra-individual reliability over time serves to validate the notion that these measures reflect meaningful individual differences that can be utilised in basic research and clinical studies

Using generative models to make probabilistic statements about hippocampal engagement in MEG

Magnetoencephalography (MEG) enables non-invasive real time characterization of brain activity. However, convincing demonstrations of signal contributions from deeper sources such as the hippocampus remain controversial and are made difficult by its depth, structural complexity and proximity to neocortex. Here, we demonstrate a method for quantifying hippocampal engagement probabilistically using simulated hippocampal activity and realistic anatomical and electromagnetic source modelling. We construct two generative models, one which supports neuronal current flow on the cortical surface, and one which supports it on both the cortical and hippocampal surfaces. Using Bayesian model comparison, we then infer which of the two models provides a more likely explanation of the dataset at hand. We also carry out a set of control experiments to rule out bias, including simulating medial temporal lobe sources to assess the risk of falsely positive results, and adding different types of displacements to the hippocampal portion of the mesh to test for anatomical specificity of the results. In addition, we test the robustness of this inference by adding co-registration and sensor level noise. We find that the model comparison framework is sensitive to hippocampal activity when co-registration error is -20 dB. These levels of co-registration error and SNR can now be achieved empirically using recently developed subject-specific head-casts

Ground-based detection of sodium in the transmission spectrum of exoplanet HD209458b

[Context] The first detection of an atmosphere around an extrasolar planet was presented by Charbonneau and collaborators in 2002. In the optical transmission spectrum of the transiting exoplanet HD209458b, an absorption signal from sodium was measured at a level of 0.023+-0.006%, using the STIS spectrograph on the Hubble Space Telescope. Despite several attempts, so far only upper limits to the Na D absorption have been obtained using telescopes from the ground, and the HST result has yet to be confirmed. [Aims] The aims of this paper are to re-analyse data taken with the High Dispersion Spectrograph on the Subaru telescope, to correct for systematic effects dominating the data quality, and to improve on previous results presented in the literature. [Methods] The data reduction process was altered in several places, most importantly allowing for small shifts in the wavelength solution. The relative depth of all lines in the spectra, including the two sodium D lines, are found to correlate strongly with the continuum count level in the spectra. These variations are attributed to non-linearity effects in the CCDs. After removal of this empirical relation the uncertainties in the line depths are only a fraction above that expected from photon statistics. [Results] The sodium absorption due to the planet's atmosphere is detected at >5 sigma, at a level of 0.056+-0.007% (2x3.0 Ang band), 0.070+-0.011% (2x1.5 Ang band), and 0.135+-0.017% (2x0.75 Ang band). There is no evidence that the planetary absorption signal is shifted with respect to the stellar absorption, as recently claimed for HD189733b. The measurements in the two most narrow bands indicate that some signal is being resolved.[abridged]Comment: Latex, 7 pages: accepted for publication in Astronomy & Astrophysic

Adaptive Functional Diversification of Lysozyme in Insectivorous Bats

This work was supported by the National Natural Science Foundation of China (31172077 to S.Z.), an East China Normal University Fostering Project for National Top Hundred Doctoral Dissertations (PY2011012 to Y.L.), an Innovation Fund of East China Normal University (78210200 to G.H.), and a Biotechnology and Biological Sciences Research Council China Partnering Award (BB/G530392/1 to G.J., S.J.R., and S.Z.)

A phylogenomic analysis of the role and timing of molecular adaptation in the aquatic transition of cetartiodactyl mammals

This work was funded by the European Research Council (ERC 1076 Starting grant no. 310482) awarded to S.J.R. and a Newton International Fellowship awarded to M.R.M

Non-invasive laminar inference with MEG: comparison of methods and source inversion algorithms

Magnetoencephalography (MEG) is a direct measure of neuronal current flow; its anatomical resolution is therefore not constrained by physiology but rather by data quality and the models used to explain these data. Recent simulation work has shown that it is possible to distinguish between signals arising in the deep and superficial cortical laminae given accurate knowledge of these surfaces with respect to the MEG sensors. This previous work has focused around a single inversion scheme (multiple sparse priors) and a single global parametric fit metric (free energy). In this paper we use several different source inversion algorithms and both local and global, as well as parametric and non-parametric fit metrics in order to demonstrate the robustness of the discrimination between layers. We find that only algorithms with some sparsity constraint can successfully be used to make laminar discrimination. Importantly, local t-statistics, global cross-validation and free energy all provide robust and mutually corroborating metrics of fit. We show that discrimination accuracy is affected by patch size estimates, cortical surface features, and lead field strength, which suggests several possible future improvements to this technique. This study demonstrates the possibility of determining the laminar origin of MEG sensor activity, and thus directly testing theories of human cognition that involve laminar- and frequency-specific mechanisms. This possibility can now be achieved using recent developments in high precision MEG, most notably the use of subject-specific head-casts, which allow for significant increases in data quality and therefore anatomically precise MEG recordings