Seizure warning algorithm based on optimization and nonlinear dynamics

There is growing evidence that temporal lobe seizures are preceded by a preictal transition, characterized by a gradual dynamical change from asymptomatic interictal state to seizure. We herein report the first prospective analysis of the online automated algorithm for detecting the preictal transition in ongoing EEG signals. Such, the algorithm constitutes a seizure warning system. The algorithm estimates STL_max, a measure of the order or disorder of the signal, of EEG signals recorded from individual electrode sites. The optimization techniques were employed to select critical brain electrode sites that exhibit the preictal transition for the warning of epileptic seizures. Specifically, a quadratically constrained quadratic 0-1 programming problem is formulated to identify critical electrode sites. The automated seizure warning algorithm was tested in continuous, long-term EEG recordings obtained from 5 patients with temporal lobe epilepsy. For individual patient, we use the first half of seizures to train the parameter settings, which is evaluated by ROC (Receiver Operating Characteristic) curve analysis. With the best parameter setting, the algorithm applied to all cases predicted an average of 91.7% of seizures with an average false prediction rate of 0.196 per hour. These results indicate that it may be possible to develop automated seizure warning devices for diagnostic and therapeutic purposes.Mathematics Subject Classification (1991):20E28, 20G40, 20C20     

PHOTOSENSITIZATION WITH BACTERIOCHLORINS

Abstract— Biophysical and photobiological properties of a group of bacteriochlorins were compared with efficacy of these products for photodynamic therapy of murine tumors. Predictive factors for selective photosensitization in vivo include affinity binding to lipoproteins greater than albumin, extinction coefficient at the wavelength of irradiation and tumor/skin distribution. Efficacy was correlated with circulating plasma levels of the different sensitizers but not with the photodynamic therapy response in cell culture.     

Reconstitution of Nucleosome Demethylation and Catalytic Properties of a Jumonji Histone Demethylase

1. Download : Download high-res image (283KB)
2. Download : Download full-size image

Highlights? Catalytic domain of JMJD2A (cJMJD2A) removes methyl marks in a distributive manner ? Homogeneously methylated nucleosomes were used as substrates ? Quantitative assay for nucleosome demethylation has been developed     

Dynamic stability of rotor-bearing systems subjected to random axial forces

This paper investigates the lateral vibration of a spinning disk-shaft system supported by a pair of ball bearings and subjected to a pair of random axial forces at both ends. The axial forces are assumed as the sum of a static force and a random process with a zero mean. Due to the random axial forces, the rotor-bearing system may experience parametric random instability under certain situations. In this work, the finite element method is applied to yield a set of discretized system equations first. The set of discretized system equations is partially uncoupled by the modal analysis procedure suitable for gyroscopic systems. The stochastic averaging method is then adopted to obtain Ito's equations for the response amplitudes of the system. Finally the first- and second-moment stability criteria are utilized to determine the stability boundaries of the system. Numerical results show that the rotor-bearing system is always stable in the sense of the first-moment stability, and the effects of the average axial compressive force and the disk mass, which will lower all frequencies of the system, tend to destabilize the second-moment stability of the system.     

Synergistic antitumor effect of curcumin and dinitrosyl iron complexes for against melanoma cells

The aim of this study was to examine whether combining curcumin, a chemoprevention agent, and dinitrosyl iron complexes (DNICs) would have a synergistic cytotoxic effect on mouse melanoma B16-F10 cells in vitro. Three synthesized DNICs-[PPN] [(NO)₂Fe(SCH₂CONHCH₃)₂] (NC01), [PPN] [(NO)₂Fe(SCH₂CON(CH₃)₂)₂] (NC02), and [Na][(NO)₂Fe(SCH₂CON(CH₃)₂)₂] (NC03) were tested in this study. In vitro DNA cleavage assay showed all three DNICs could cause plasmid DNA damage through releasing NO under UV irradiation. The cytotoxicity assay demonstrated these DNICs were toxic to B16-F10 cells in vitro, and the estimated values of LD₅₀ (24 h of incubation) of NC01 and NC02 were 1 μM, while the values of LD₅₀ of NC03 was 200 μM. No synergistic cytotoxicity effect was noted in the treatments of the combinations of curcumin and DNICs. On the contrary, in the presence of NC03, the toxicity of curcumin was reduced. Using UV-Visible spectroscopy and fluorescence microscopy, we found NC03 might interact with curcumin and reduce the accumulation of curcumin in cells. Further experiments using the pretreatment of curcumin for 4 h followed by the treatment of NC03 showed the synergistic cytotoxic effect, while, the pretreatment of NC03 followed by the treatment of curcumin did not have any effect. This study provides the basis for further investigation on the effects of combinations of curcumin and other NO donors.     

Nonlinear electro-optic characteristic in a photoexcited semiconductor

We study the transport properties of a GaAs-based Gunn device under local optical excitation via direct numerical simulation. The simulation results show that the hysteretic transition in between quenched and transit modes. The key mechanism for this kind of transition is related to the formation of a stationary and nonuniform hole profile around the notch regime. Therefore, the development of optical control of the microwave output is reported. In addition, the influence of impact ionization on this nonlinear semiconductor is also discussed in the present study.     

Synthesis and optical and electrochemical properties of copolymers consisting of 9,9‐dihexylfluorene and aromatic triazole chromophores

Aromatic triazole chromophores were incorporated into polyfluorene in an attempt to increase electron affinity, to promote emission efficiency, and to diminish excimer formation. Poly(9,9‐dihexylfluorene) ( P1 ) and new copolymers with aromatic triazoles ( P2 – P4 ) were prepared by Suzuki coupling polymerization. In P2 , the aromatic triazole (3.8 mol %) was attached exclusively as terminal groups, whereas P3 and P4 were main‐chain copolymers containing 3.9 and 10.3 mol % aromatic triazole chromophores, respectively. The copolymers were soluble in common organic solvents and showed high decomposition temperatures (437–458 °C). The twisted structure between the triazole and fluorene increased the emission efficiency and effectively prevented excimer formation in P2 – P4 . After the introduction of the triazole units, the absorption spectra showed a blueshift (from 388 to 381 nm in chloroform) due to confined conjugation, but the photoluminescence spectra remained almost the same (417–418 nm); this was attributed to oligofluorene segments. No emission of triazole fluorophores was observed because of efficient energy transfer from the triazole to oligofluorene segments. However, incomplete energy transfer was observed in CH₃COOH. The optical stability upon thermal annealing was also improved by the incorporation of aromatic triazole segments. From cyclic voltammetry results, P2 – P4 , containing triazole groups, showed greater electron affinity (lowest unoccupied molecular orbital level = ?2.67 to ?2.71 eV) than P1 (?2.52 eV). Electroluminescence devices of P1 – P4 all exhibited excimer emissions (483–521 nm), which could also be diminished by the introduction of aromatic triazole chromophores. © 2006Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 136–146, 2007     

Nanodiamond-based two-step sampling of multiply and singly phosphorylated peptides for MALDI-TOF mass spectrometry analysis

Simultaneous detection of multiply and singly phosphorylated peptides using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is challenging because of suppression effects during ionization. In oder to overcome this problem, this study presents a new approach to improve the detection of phosphopeptides by stepwise enrichment using polyarginine-coated (PA-coated) and titanium dioxide-coated (TiO(2)-coated) nanodiamonds for fractionation of multiply and singly phosphorylated peptides prior to on-probe MALDI MS analysis. The feasibility of this approach was demonstrated using synthetic peptides containing different numbers of phosphate groups, tryptic digests of α-casein, β-casein, and complex protein mixtures. The high specificity of the approach is shown in its effective enrichment and fractionation of phosphopeptides from the digest of β-casein and bovine serum albumin at a molar ratio as low as 1 : 1000, which out-performs the commercial Fe(3+)-IMAC and TiO(2) isolation kits. It offers a simple and effective alternative for the fractionation and identification of multiply and singly phosphorylated peptides by MALDI MS and allows for deduction of more information from limited starting materials.     

The Synthesis and Chemistry of 9-Chlorobicyclo[6.1.0]Non-1(9)-Ene

9-Chlorobicyclo[6.1.0]non-l(9)-ene ( 4 ), a 2-chlorinated 1,3-fused cyclopropene, is synthesized and isolated from the dehalogenation of the l-bromo-9,9-dichlorobicyclo[6.1.0]nonane, itself derived from cyclooctene. Compound 4 undergoes ring opening reaction to generate cyclooctenyl chlorocarbene ( 9 ) which reacts with water via conjugate addition and ipso-addition to give ( E )-2-(chloromethylene)cyclooctanol ( 7 ) and cyclooctene-l-carboxaldehyde ( 8 ), respectively. The conjugate addition of 9 with water is more favorable than the ipso-addition by 3:1. Compound 4 , which is stable at ?25 °C for weeks without any decomposition, reacts with oxygen to produce 2-chlorocyclonon-2-enone ( 12 ) via the ring-opening reaction adduct, vinyl alkylcarbene 10 .