Time-frequency MEG-MUSIC algorithm

We propose a method that incorporates the time-frequency characteristics of neural sources into magnetoencephalographic (MEG) source estimation. The method is based on the multiple-signal-classification (MUSIC) algorithm and it calculates a time--frequency matrix in which diagonal and off-diagonal terms are the auto and crosstime--frequency distributions of multichannel MEG recordings, respectively. The method averages this time-frequency matrix over the time--frequency region of interest. The locations of neural sources are then estimated by checking the orthogonality between the noise subspace of this averaged matrix and the sensor lead field. Accordingly, the method allows us to estimate the locations of neural sources from each time--frequency component. A computer simulation was performed to test the validity of the proposed method, and the results demonstrate its effectiveness.     

Synthesis and Physical Properties of (Cu,M)Ba2Ca3Cu4Oz (M=C,Mg,Ni,Al,Zn,Tl)

We have synthesized the single phase samples of Cu _x C _0.1 Ba ₂ Ca ₃ Cu ₄ O _z (x=0.20.9). Transport and magnetic measurements and iodometric titration analysis were carried out for these materials. From these results we discuss the correlation between T _c , the Hall number, copper valence and oxygen content. The effect of the substituted M ions on T _c in (CuC, M)-l234 (M=Ni,Zn,Al,TI,Mg) is also discussed. We propose a unique selective carrier-doping mechanism in (Cu,C)- and (CuC,Mg)-1234 systems.     

Endothelin A-receptor blockade worsens endotoxin-induced hepatic microcirculatory changes and necrosis

BACKGROUND & AIMS: Endothelin 1 is considered to be an important regulator of sinusoidal blood flow and increases during endotoxemia. The purpose of this study was to investigate the role of endothelin 1 in hepatic microcirculation, oxygen transport, and liver injury during endotoxemia. METHODS: Male Sprague-Dawley rats were continuously infused with 2.5 mL/h of saline, 0.8 mg . kg-1 . h-1 of lipopolysaccharide (LPS), 3 mg . kg-1 . h-1 of BQ-485, an endothelin A-receptor antagonist, or LPS plus BQ-485 for 7 hours. RESULTS: BQ-485 infusion had no significant effect on hepatic microcirculation and liver injury. LPS increased the plasma levels of aspartate aminotransferase (AST) and total bilirubin and decreased the hepatic adenosine triphosphate (ATP) level and bile flow rate. LPS + BQ-485 infusion further increased the plasma levels of AST and total bilirubin and decreased the bile flow rate and the hepatic ATP level. Dual-spot microspectroscopy revealed mild decreases in sinusoidal erythrocyte velocity and oxygen transport in the LPS group and profound decreases in these parameters in the LPS + BQ-485 group. Histological examinations revealed massive necrotic changes in the pericentral regions of the LPS + BQ-485 group. CONCLUSIONS: These results suggest that blockade of endothelin A receptors disturbs hepatic microcirculation and oxygen transport and aggravates the necrotic injury induced by endotoxin.     

Structures of spider toxins: hydroxyindole-3-acetylpolyamines and a new generalized structure of type-E compounds obtained from the venom of the Joro spider, Nephila clavata

Facile structure determination of acylpolyamines, glutamatergic nerve blocker obtained from the venom of the Joro spider (Nephila clavata) was carried out with the use of micro-column LC/MS and high energy collision induced dissociation (CID) mass spectrometry. 6-hydroxyindole-3-acetyl was proposed previously as a putative partial structure, for the acyl moiety of hydroxyindole-type polyamines (NPTX-1 to -6). The NMR data obtained for NPTX-6, NPTX-687 and hydroxyindole-3-acetic acid which was released by acid hydrolysis of Nephila clavata crude venom extracts proved that the lipophilic head is the 4-hydroxyindole-3-acetic acid. Various hydroxyindole-3-acetyl polyamines were found in N. Clavata venom and characterized by mass spectrometry. As a result, type-E, a new class of generalized acylpolyamine structure was proposed in addition to the previously reported polyamine backbones type-A to -D.     

Evidence against a direct role for the induction of c-jun expression in the mediation of drug-induced apoptosis in human acute leukemia cells

Previous reports have demonstrated that a variety of anticancer drugs, e.g., 1-beta-D-arabinofuranosylcytosine (ara-C), mitoxantrone, etoposide, camptothecin, and cisplatin, induce the expression of c-jun oncogene in leukemic cells prior to producing internucleosomal DNA fragmentation and the morphological features of apoptosis. This has led to the impression that the induction of c-jun expression may be directly involved in the molecular signaling of the final common pathway of programmed cell death or apoptosis. In the present study, we examined the role of c-jun expression in three different settings of anticancer drug-induced apoptosis in human leukemic cells. First, exposure of human myeloid leukemia HL-60 cells to high-dose ara-C for 4 h produced internucleosomal DNA fragmentation preceded by c-jun induction. However, pretreatment of HL-60 cells with staurosporine, a protein kinase C inhibitor, repressed c-jun yet enhanced DNA fragmentation and apoptosis due to ara-C. Second, in human pre-B leukemia 697/BCL-2 cells which are transfected with the cDNA of the bcl-2 oncogene and overexpress p26BCL-2, although ara-C or mitoxantrone treatment caused greater c-jun induction than in the 697/neo cells, significantly reduced endonucleolytic DNA fragmentation and apoptosis was observed in 697/BCL-2 cells. Finally, taxol-induced internucleosomal DNA fragmentation and morphological features of apoptosis in HL-60 cells were not associated with the induction of c-jun expression. These lines of evidence indicate that the induction of c-jun expression may not have a direct role in the molecular signaling of anticancer drug-induced apoptosis, and that the anticancer drug-induced apoptosis can occur by a mechanism that does not involve the induction of c-jun expression.     

Fabrication of low-loss single-mode fibres

Low-loss single-mode fibres with GeO2-doped SiO2 cores have been made by the c.v.d. method and the loss spectrum from 0.6 to 1.8 ?m measured. The minimum loss of the fibre with suitably designed parameters, characterised by the refractive-index difference and the core diameter, was 0.75 dB/km at 1.05 ?m.     

Simulation of confined and enhanced optical near fields for a long narrow aperture in a pyramidal structure on a thick metallic screen

A new type of long narrow aperture in a pyramidal structure on a thick metallic screen is proposed, and optical wave scattering by this structure is simulated. This aperture structure provides high emission intensity and small spot size simultaneously through excitation of the surface plasmon polaritons on the sidewalls of the pyramidal structure. Scattering of optical waves by this structure in the thick metallic screen is solved numerically with a volume integral equation by generalized conjugate residual iteration and fast Fourier transformation. The basic characteristics of the near-field intensities of the aperture are investigated in detail.