Accuracy improvement of quantitative analysis in laser-induced breakdown spectroscopy using modified wavelet transform

A modified algorithm of background removal based on wavelet transform was developed for spectrum correction in laser-induced breakdown spectroscopy (LIBS). The optimal type of wavelet function, decomposition level and scaling factor γ were determined by the root-mean-square error of calibration (RMSEC) of the univariate regression model of the analysis element, which is considered as the optimization criteria. After background removal by this modified algorithm with RMSEC, the root-mean-square error of cross-validation (RMSECV) and the average relative error (ARE) criteria, the accuracy of quantitative analysis on chromium (Cr), vanadium (V), cuprum (Cu), and manganese (Mn) in the low alloy steel was all improved significantly. The results demonstrated that the algorithm developed is an effective pretreatment method in LIBS to significantly improve the accuracy in the quantitative analysis.

Flame-enhanced laser-induced breakdown spectroscopy

Flame-enhanced laser-induced breakdown spectroscopy (LIBS) was investigated to improve the sensitivity of LIBS. It was realized by generating laser-induced plasmas in the blue outer envelope of a neutral oxy-acetylene flame. Fast imaging and temporally resolved spectroscopy of the plasmas were carried out. Enhanced intensity of up to 4 times and narrowed full width at half maximum (FWHM) down to 60% for emission lines were observed. Electron temperatures and densities were calculated to investigate the flame effects on plasma evolution. These calculated electron temperatures and densities showed that high-temperature and low-density plasmas were achieved before 4 µs in the flame environment, which has the potential to improve LIBS sensitivity and spectral resolution.

Accuracy improvement on polymer identification using laser-induced breakdown spectroscopy with adjusting spectral weightings

A new approach to polymer identification by laser-induced breakdown spectroscopy (LIBS) with adjusting spectral weightings (ASW) was developed in this work aiming at improving the identification accuracy. This approach has been achieved through increasing the intensities of specific characteristic spectral lines which are important to polymer identification but difficult to be excited. Using the ASW method, the identification accuracies of all 11 polymers were increased to nearly 100%, while the accuracies of PE, PU, PP and PC were only 98%, 74%, 90% and 98%, respectively, without using the ASW method.

Contrast enhancement using silica microspheres in coherent anti-Stokes Raman spectroscopic imaging

Coherent anti-Stokes Raman scattering (CARS) microscopy is a powerful imaging technique that can provide chemical information of organic and nonorganic materials through vibrational spectroscopy. However, its contrast is not sufficient for monitoring thin film materials. In this study, silica microspheres were employed for enhancing the signal contrast in CARS imaging. One layer of optically transparent silica microspheres was self-assembled onto polymer grating samples to enhance the CARS signals. The highest contrast enhancement factor of 12.5 was achieved using 6.1-μm-diameter microspheres. Finite-difference time-domain method (FDTD) simulation was conducted to simulate the contrast enhancement with silica microspheres of different diameters.

Deficiency of asparagine synthetase causes congenital microcephaly and a progressive form of encephalopathy

We analyzed four families that presented with a similar condition characterized by congenital microcephaly, intellectual disability, progressive cerebral atrophy, and intractable seizures. We show that recessive mutations in the ASNS gene are responsible for this syndrome. Two of the identified missense mutations dramatically reduce ASNS protein abundance, suggesting that the mutations cause loss of function. Hypomorphic Asns mutant mice have structural brain abnormalities, including enlarged ventricles and reduced cortical thickness, and show deficits in learning and memory mimicking aspects of the patient phenotype. ASNS encodes asparagine synthetase, which catalyzes the synthesis of asparagine from glutamine and aspartate. The neurological impairment resulting from ASNS deficiency may be explained by asparagine depletion in the brain or by accumulation of aspartate/glutamate leading to enhanced excitability and neuronal damage. Our study thus indicates that asparagine synthesis is essential for the development and function of the brain but not for that of other organs.

Filamin A regulates MMP-9 expression and suppresses prostate cancer cell migration and invasion

This study aims to analyze the expression and clinical significance of Filamin A (FLNA) in prostate carcinoma and the biological effect in its cell line by FLNA overexpression. Immunohistochemistry and Western blot were used to analyze FLNA protein expression in 68 cases of prostate cancer and 37 cases of normal tissues to study the influence of the upregulated expression of FLNA that might be found on PC-3 cell biological effect. In the immunohistochemical analysis, the level of FLNA protein expression was found to be significantly lower in prostate cancer tissue than in normal tissues (P < 0.05). In the Western blot analysis, the relative amount of FLNA protein in prostate cancer tissue was found to be significantly lower than in normal tissues (P < 0.05). The level of FLNA protein expression was not correlated with age and PSA concentration (P > 0.05), but it was correlated with T stages, lymph node metastasis, clinic stage, and Gleason score (P < 0.05). The result of biological function showed that PC-3 cell transfected FLNA had a lower survival fraction, a significant decrease in migration and invasion, and a lower matrix metallopeptidase 9 (MMP-9) protein expression compared with PC-3 cell untransfected FLNA (P < 0.05). FLNA expression decreased in prostate cancer and correlated significantly with T stages, lymph node metastasis, clinic stage, and Gleason score, suggesting that FLNA may play important roles as a negative regulator to prostate cancer PC-3 cell by promoting the degradation of MMP-9.

EMP1 inhibits nasopharyngeal cancer cell growth and metastasis through induction apoptosis and angiogenesis

This study aimed to analyze the expression, clinical significance of epithelial membrane protein-1 (EMP1) in nasopharyngeal carcinoma, and the biological effect in its cell line by EMP1 overexpression. Immunohistochemistry and Western blot were used to analyze the EMP1 protein expression in 75 cases of nasopharyngeal cancer and 31 cases of normal tissues to study the relationship between EMP1 expression and clinical factors. Recombinant lentiviral vector was constructed to overexpress EMP1 and then infect nasopharyngeal cancer CNE2 cell line. Quantitative real-time RT-PCR and Western blot were used to detect the mRNA level and protein of EMP1. MTT assay, cell apoptosis, migration, and invasion assays were also conducted to determine the influence of the upregulated expression of EMP1 that might be found on CNE2 cells' biological effect. Immunohistochemistry and Western blot: The level of EMP1 protein expression was found to be significantly lower in nasopharyngeal cancer tissue than in the normal tissues (P < 0.05). Decreased expression of EMP1 was significantly correlated with T stages, lymph node metastasis, clinic stage, and histological grade of patients with nasopharyngeal cancer (P < 0.05). Meanwhile, the loss of EMP1 expression correlated significantly with poor overall survival time by Kaplan-Meier analysis (P < 0.05). The result of biological function has shown that CNE2 cell-transfected EMP1 had a lower survival fraction, higher cell apoptosis, significant decrease in migration and invasion, higher caspase-9, and lower vascular endothelial growth factor C protein expression compared with CNE2 cell-untransfected EMP1 (P < 0.05). EMP1 expression decreased in nasopharyngeal cancer and correlated significantly T stages, lymph node metastasis, clinic stage, histological grade, and poor overall survival, suggesting that EMP1 may play important roles as a negative regulator to nasopharyngeal cancer cell.

De novo mutations in epileptic encephalopathies

Epileptic encephalopathies are a devastating group of severe childhood epilepsy disorders for which the cause is often unknown. Here we report a screen for de novo mutations in patients with two classical epileptic encephalopathies: infantile spasms (n = 149) and Lennox-Gastaut syndrome (n = 115). We sequenced the exomes of 264 probands, and their parents, and confirmed 329 de novo mutations. A likelihood analysis showed a significant excess of de novo mutations in the ∼4,000 genes that are the most intolerant to functional genetic variation in the human population (P = 2.9 × 10(-3)). Among these are GABRB3, with de novo mutations in four patients, and ALG13, with the same de novo mutation in two patients; both genes show clear statistical evidence of association with epileptic encephalopathy. Given the relevant site-specific mutation rates, the probabilities of these outcomes occurring by chance are P = 4.1 × 10(-10) and P = 7.8 × 10(-12), respectively. Other genes with de novo mutations in this cohort include CACNA1A, CHD2, FLNA, GABRA1, GRIN1, GRIN2B, HNRNPU, IQSEC2, MTOR and NEDD4L. Finally, we show that the de novo mutations observed are enriched in specific gene sets including genes regulated by the fragile X protein (P < 10(-8)), as has been reported previously for autism spectrum disorders.

Accuracy improvement of quantitative analysis by spatial confinement in laser-induced breakdown spectroscopy

To improve the accuracy of quantitative analysis in laser-induced breakdown spectroscopy, the plasma produced by a Nd:YAG laser from steel targets was confined by a cavity. A number of elements with low concentrations, such as vanadium (V), chromium (Cr), and manganese (Mn), in the steel samples were investigated. After the optimization of the cavity dimension and laser fluence, significant enhancement factors of 4.2, 3.1, and 2.87 in the emission intensity of V, Cr, and Mn lines, respectively, were achieved at a laser fluence of 42.9 J/cm(2) using a hemispherical cavity (diameter: 5 mm). More importantly, the correlation coefficient of the V I 440.85/Fe I 438.35 nm was increased from 0.946 (without the cavity) to 0.981 (with the cavity); and similar results for Cr I 425.43/Fe I 425.08 nm and Mn I 476.64/Fe I 492.05 nm were also obtained. Therefore, it was demonstrated that the accuracy of quantitative analysis with low concentration elements in steel samples was improved, because the plasma became uniform with spatial confinement. The results of this study provide a new pathway for improving the accuracy of quantitative analysis of LIBS.

Laser-assisted solid-state synthesis of carbon nanotube/silicon core/shell structures

A single-step solid-state synthetic approach was developed for the synthesis of silicon-coated carbon nanotube (CNT) core/shell structures. This was achieved through laser-induced melting and evaporation of CNT-deposited Si substrates using a continuous wavelength CO2 laser. The synthesis location of the CNT/Si structures was defined by the laser-irradiated spots. The thickness of the coating was controlled by tuning the laser power and synthesis time during the coating process. This laser-based synthetic technique provides a convenient approach for solid-state, controllable, gas-free, simple and cost-effective fabrication of CNT/Si core/shell structures.

Plasmonic-enhanced carbon nanotube infrared bolometers

Plasmonic nanoantennas show significant potential in photodetection applications, but the extent to which their full potential can be realized is dictated by the volume and location of the active materials within the plasmonic structure. Carbon nanotubes (CNTs) have been used as a novel material in photodetection application due to their excellent electronic and optoelectronic properties. However, difficulties in the integration of CNTs in the gaps of nanoantennas have limited the investigation of antenna-coupled CNT detectors. Here, we demonstrate a unique plasmonic approach for selectively growing CNTs in the gap of nanoantenna arrays for fabrication of plasmonic infrared bolometers operating at room temperature. Strong concentration of light at the tips of nanoantennas was utilized for localized heating and growth of CNTs. Moreover, interaction of this strong optical field with the small volume of CNTs enhanced the photoresponse of the bolometers. Consequently, a high responsivity of about 800 V W(-1) was achieved at room temperature.

Surface-enhanced Raman spectroscopy using gold-coated horizontally aligned carbon nanotubes

Gold-coated horizontally aligned carbon nanotube (Au-HA-CNT) substrates were fabricated for surface-enhanced Raman spectroscopy (SERS). The Au-HA-CNT substrates, which are granular in nature, are easy-to-prepare with large SERS-active area. Enhancement factors (EFs) of ∼10(7) were achieved using the Au-HA-CNTs as substrates for rhodamine 6G (R6G) molecules. Maximum enhancement was found when the polarization direction (E-field) of the incident laser beam was parallel to the aligned direction of the HA-CNTs. Simulations using the finite-difference time-domain (FDTD) method were carried out for the granular Au-HA-CNT samples. Enhancement mechanisms and determination of EFs were analyzed. Biological samples, including (13)C- and deuterium (D)-labeled fatty acids and Coccomyxa sp. c-169 microalgae cells, were also measured using this SERS substrate. The limits of detection (LODs) of D- and (13)C-labeled fatty acids on the SERS substrate were measured to be around 10 nM and 20 nM, respectively. Significantly enhanced Raman signals from the microalgae cells were acquired using the SERS substrate.

Optimally enhanced optical emission in laser-induced breakdown spectroscopy by combining spatial confinement and dual-pulse irradiation

In laser-induced breakdown spectroscopy (LIBS), a pair of aluminum-plate walls were used to spatially confine the plasmas produced in air by a first laser pulse (KrF excimer laser) from chromium (Cr) targets with a second laser pulse (Nd:YAG laser at 532 nm, 360 mJ/pulse) introduced parallel to the sample surface to re-excite the plasmas. Optical emission enhancement was achieved by combing the spatial confinement and dual-pulse LIBS (DP-LIBS), and then optimized by adjusting the distance between the two walls and the interpulse delay time between both laser pulses. A significant enhancement factor of 168.6 for the emission intensity of the Cr lines was obtained at an excimer laser fluence of 5.6 J/cm(2) using the combined spatial confinement and DP-LIBS, as compared with an enhancement factor of 106.1 was obtained with DP-LIBS only. The enhancement mechanisms based on shock wave theory and reheating in DP-LIBS are discussed.

Stress and phase purity analyses of diamond films deposited through laser-assisted combustion synthesis

Diamond films were deposited on silicon and tungsten carbide substrates in open air through laser-assisted combustion synthesis. Laser-induced resonant excitation of ethylene molecules was achieved in the combustion process to promote diamond growth rate. In addition to microstructure study by scanning electron microscopy, Raman spectroscopy was used to analyze the phase purity and residual stress of the diamond films. High-purity diamond films were obtained through laser-assisted combustion synthesis. The levels of residual stress were in agreement with corresponding thermal expansion coefficients of diamond, silicon, and tungsten carbide. Diamond-film purity increases while residual stress decreases with an increasing film thickness. Diamond films deposited on silicon substrates exhibit higher purity and lower residual stress than those deposited on tungsten carbide substrates.

Enhancement of optical emission from laser-induced plasmas by combined spatial and magnetic confinement

To enhance optical emission in laser-induced breakdown spectroscopy, both a pair of permanent magnets and an aluminum hemispherical cavity (diameter: 11.1 mm) were used simultaneously to magnetically and spatially confine plasmas produced by a KrF excimer laser in air from pure metal and alloyed samples. High enhancement factors of about 22 and 24 in the emission intensity of Co and Cr lines were acquired at a laser fluence of 6.2 J/cm2 using the combined confinement, while enhancement factors of only about 11 and 12 were obtained just with a cavity. The mechanism of enhanced optical emission by combined confinement, including shock wave in the presence of a magnetic field, is discussed. The Si plasmas, however, were not influenced by the presence of magnets as Si is hard to ablate and ionize and hence has less free electrons and positive ions. Images of the laser-induced Cr and Si plasmas show the difference between pure metallic and semiconductor materials in the presence of both a cavity and magnets.

Fast growth of branched nickel monosilicide nanowires by laser-assisted chemical vapor deposition

Branched nickel monosilicide (NiSi) nanowires (NWs), for the first time, have been synthesized on Ni foams by laser-assisted chemical vapor deposition using disilane precursor molecules. Studies indicate that 600 °C is the threshold temperature for the growth of a large number of branched NiSi NWs with 100-500 nm long branches extending from the main stems. Below the threshold temperature, unbranched NiSi NWs were obtained. The density of the branched NiSi NWs is relatively higher in comparison to that of the unbranched ones. The growth rate of the branched NiSi NWs at 700 °C is estimated up to 10 µm min(-1). High-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy of the branched NiSi NWs suggest that the formation of these branched nanostructures is ascribed to the Ni-dominant diffusion process. These NiSi NWs with branched nanostructures could bring them new opportunities in nanodevices.

Generation of high-temperature and low-density plasmas for improved spectral resolutions in laser-induced breakdown spectroscopy

Improved spectral resolutions were achieved in laser-induced breakdown spectroscopy (LIBS) through generation of high-temperature and low-density plasmas. A first pulse from a KrF excimer laser was used to produce particles by perpendicularly irradiating targets in air. A second pulse from a 532 nm Nd:YAG laser was introduced parallel to the sample surface to reablate the particles. Optical scattering from the first-pulse plasmas was imaged to elucidate particle formation in the plasmas. Narrower line widths (full width at half maximums: FWHMs) and weaker self-absorption were observed from time-integrated LIBS spectra. Estimation of plasma temperatures and densities indicates that high temperature and low density can be achieved simultaneously in plasmas to improve LIBS resolutions.

Resonant excitation of precursor molecules in improving the particle crystallinity, growth rate and optical limiting performance of carbon nano-onions

A catalyst-free and highly efficient synthetic method for growing carbon nano-onions (CNOs) in open air has been developed through the laser resonant excitation of a precursor molecule, ethylene, in a combustion process. Highly concentric CNO particles with improved crystallinity were obtained at a laser wavelength of 10.532 µm through the resonant excitation of the CH(2) wagging mode of the ethylene molecules. A higher growth rate up to 2.1 g h( - 1) was obtained, compared with that without a laser (1.3 g h( - 1)). Formation of the CNOs with ordered graphitic shells is ascribed to the decomposition of polycyclic aromatic hydrocarbons (PAHs) into C(2) species. The optical limiting performances of the CNOs grown by the combustion processes were investigated. CNOs grown at 10.532 µm laser excitation demonstrated improved optical limiting properties due to the improved crystallinity.

Formation and inhibition of cholesterol oxidation products in tea-leaf eggs during marinating

The objectives of this study were to develop a GC-MS method for determination of cholesterol oxidation products (COPs) in tea-leaf eggs and study the formation and inhibition of COPs as affected by heating time and various ingredients in marinated juice. The various COPs in egg and juice samples were extracted by a solvent system of chloroform/methanol (2:1, v/v), followed by purification using a silica cartridge and GC-MS for subsequent separation and quantitation, with high recovery ranges from 85.9 to 98.3% and from 83.1-100.1% being obtained for egg and juice, respectively. 5α-Cholestane was shown to be an appropriate internal standard for quantitation. A total of five COPs, including 7-keto, 5,6 β-EP, 7α-OH, 7β-OH, and triol, were formed in tea-leaf eggs during marinating, but not in marinated juice. A peak level of total COPs (2272.2 ng/g) was generated in tea-leaf eggs after 24 h of heating, but reduced to 1068.2 ng/g in 48 h. Both the total phenolic and flavonoid compounds in tea-leaf eggs showed a time-dependent increase during marinating and so did the pH and browning index in tea-leaf eggs and juice. The incorporation of soy sauce or black tea leaf into juice was effective in inhibiting COPs formation in tea-leaf eggs, with the latter being more pronounced than the former. The formation of Maillard reaction products during marinating as well as the presence of total phenolic and total flavonoid in black tea leaf was mainly responsible for COPs reduction in tea-leaf eggs.

Diameter modulation by fast temperature control in laser-assisted chemical vapor deposition of single-walled carbon nanotubes

Diameter modulation by fast temperature control in laser-assisted chemical vapor deposition (LCVD) was successfully achieved to tune the diameters of single-walled carbon nanotubes (SWNTs) in different segments. Due to the inverse relationship between the SWNT diameter and the growth temperature, SWNTs with ascending diameters were obtained by reducing the LCVD temperature from high to low. The diameter-modulated SWNTs were integrated in electrodes to form field-effect transistors (FETs) and to investigate their electronic transport properties. The SWNTs in the FET structures have electronic properties similar to Schottky diodes, indicating clear evidence of different bandgap structures at the two ends of the SWNTs. Raman spectroscopy, transmission electron microscopy, and electronic transport characteristics were studied to investigate the influence of temperature variation on the structural and electronic characteristics of the SWNTs.

Optical and field-emission properties of ZnO nanostructures deposited using high-pressure pulsed laser deposition

ZnO nanostructures were deposited on GaN (0001), Al2O3 (0001), and Si (100) substrates using a high-pressure pulsed laser deposition (PLD) method. Vertically aligned hexagonal-pyramidal ZnO nanorods were obtained on the Al2O3 and Si substrates whereas interlinked ZnO nanowalls were obtained on the GaN substrates. A growth mechanism has been proposed for the formation of ZnO nanowalls based on different growth rates of ZnO polar and nonpolar planes. Both ZnO nanorods and nanowalls exhibit a strong E2H vibration mode in the micro-Raman spectra. The corresponding fluorescence spectra of ZnO nanorods and nanowalls showed near band emission at 3.28 eV. The ZnO nanorods grown on the Si substrates exhibited better crystalline and optical properties compared with the ZnO structures grown on the GaN and Al2O3 substrates. The high aspect ratio, good vertical alignment, and better crystallinity of the ZnO nanorods with tapered tips exhibited promising field emission performance with a low turn-on field of 2 V/μm, a high current density of 7.7 mA/cm2, and a large field enhancement factor.

Towards carbon-nanotube integrated devices: optically controlled parallel integration of single-walled carbon nanotubes

Where it starts and where it goes? Controlled integration of single-walled carbon nanotubes (SWNTs) into pre-designed nano-architectures is one of the major challenges to be overcome for extensive scientific research and technological applications. Various serial assembly techniques have been proposed and developed. However, they are still a long way from practical applications due to the drawbacks on reliability, yield and cost. Here we demonstrate a laser-based strategy to achieve parallel integration of SWNTs into pre-designed nano-architectures through an optically controlled in situ growth process. Optical driving forces originated from tip-induced optical near-field enhancement and laser beam polarization were applied in this study to realize the controlled placement of SWNTs at designated sites following wanted orientations on the nanometer scale. Parallel integration of SWNT arrays was achieved by adjusting laser beam diameter to cover interested nano-architectures. The laser-based process suggests an efficient and cost-effective approach for fabricating and integrating SWNT-based devices and circuits.

Ultrabroadband optical circular polarizers consisting of double-helical nanowire structures

Recently, it was demonstrated by Gansel et al. [Science 325, 1513 (2009)] that 3D single-helical metamaterials can serve as broadband circular polarizers in the IR range. In this study, we propose a structured metamaterial with double-helical nanowires to construct circular polarizers with boarder wavelength bands in the visible-light and near-IR regions. Using the finite-difference time-domain method, we confirmed that the circular polarizers with the double-helical structures have operation bands more than 50% broader than those of the single-helical structures.

Clinical features, treatments and prognosis of the initial cases of pandemic influenza H1N1 2009 virus infection in Shanghai China

BACKGROUND AND OBJECTIVE

As of 13 December 2009, more than 208 countries and overseas territories or communities have reported laboratory-confirmed cases of pandemic influenza H1N1 2009, which have resulted in at least 10 582 deaths. As of 7 December 2009, 4328 severe cases were reported in Mainland China, resulting in 326 deaths. This study's objective was to determine the clinical features, treatments and prognosis of the initial cases of Pandemic influenza H1N1 2009 virus infection in Shanghai, China, and how its clinical features related to patient gender.

METHODS

A total of 224 confirmed 2009 influenza A/H1N1-infected patients treated and discharged by Shanghai Public Health Clinical center between 24 May and 20 July 2009 were included in the study. Patients' personal information, signs and symptoms, laboratory and imagery data, disease course, hospitalization period and seroconversion duration for viral nucleic acid after antiviral treatment were analyzed.

RESULTS

Among the 224 patients, 118 were male and 106 were female, yielding a sex ratio of 1.1:1. Approximately 52% of the patients came from Australia, and 63.8% were between 18 and 40 years old. Clinical manifestations included fever, cough and congestion of the throat, and lab findings were characterized by elevated C-reaction protein (CRP) and neutrophils. Female patients had significantly lower serum Prealbumin (PA) levels than male patients (P < 0.05). The patients' serum CRF levels significantly decreased after treatment (P < 0.05), while the levels of CD3, CD4 and CD8 significantly increased after treatment (P < 0.01). Approximately 29.9% of the patients had abnormal signs on chest computer tomography scan, and 21.9% had obvious signs indicating pneumonia. However, blood cultures were negative in these patients. The average disease course was 3.9 +/- 1.4 days, the average hospitalization period was 5.0 +/- 1.7 days, and the seroconversion duration for viral nucleic acid after antiviral treatment was 3.8 +/- 1.3 days.

CONCLUSION

Initial cases of pandemic influenza H1N1 2009 were characterized by fever, cough and throat congestion, with elevated CRP and neutrophils being the most significant lab findings. The pandemic influenza H1N1 2009 strain was able to affect multiple organs, including the hepatic synthesis of PA and immune functioning. The novel 2009 Influenza A/H1N1 virus was mild clinically, with a short disease course and good prognosis.

Spectroscopic determination of rotational temperature in C2H4/C2H2/O2 flames for diamond growth with and without tunable CO2 laser excitation

Optical emission spectroscopy (OES) and spectroscopic temperature determination were carried out to study C(2)H(4)/C(2)H(2)/O(2) flames used for diamond deposition with and without an excitation by a wavelength-tunable CO(2) laser. Strong emissions from C(2) and CH radicals were observed in the visible range in all the acquired OES spectra. When the flames were irradiated by using a continuous-wave (CW) CO(2) laser at a wavelength of 10.591 microm, the emission intensities of the C(2) and CH radicals in the flames increased owing to the laser excitation. The CO(2) laser was also tuned to a wavelength of 10.532 microm to precisely match the resonant frequency of the CH(2)-wagging vibrational mode of the C(2)H(4) molecules. OES spectroscopy of the C(2) and CH radicals were performed at different laser powers. The rotational temperatures of CH radicals in the flames were determined by analyzing the spectra of the R branch of the A(2)Delta-->X(2)Pi (0,0) electronic transition near 430 nm. The deposited diamond thin-films were characterized by scanning electron microscopy, stylus profilometry, and Raman spectroscopy. The deposition mechanism with and without the CO(2) laser excitation was discussed based on the OES spectral results.

Anti-viral mechanism of barramundi Mx against betanodavirus involves the inhibition of viral RNA synthesis through the interference of RdRp

Nervous necrosis virus (NNV) belongs to the betanodavirus of the Nodaviridae family. It is the causative agent of viral nervous necrosis (VNN) disease, and has inflicted devastating damage on the world-wide aquaculture industry. The fish that survived after the outbreak of VNN become persistently NNV-infected carriers. NNV-persistent infection has been demonstrated in a barramundi brain (BB) cell line, and it involves the type I interferon (IFN) response with the expression of Mx gene. However, little of the defense mechanism in fish cells against NNV infection is understood. In this study, the anti-NNV mechanism of barramundi Mx protein (BMx) was elucidated in cBB cells which were derived from BB cell line after serial treatments by NNV-specific antiserum and then became an NNV-free cell line. After NNV infection of cBB cells, the level of viral RNA-dependent RNA polymerase (RdRp) increased with time over a period of 24 h post-infection (hpi), but decreased when the BMx expression increased 48 and 72 hpi. When the expression of BMx was down-regulated by BMx-specific siRNA, the expression levels of viral RNA, proteins and progeny viral titers were restored. The BMx was found to colocalize with viral RdRp at the perinuclear area 24 hpi and coprecipitate with viral RdRp, indicating that they could bind with each other. Viral RdRp was also revealed to colocalize with lysosomes 48 hpi as the NNV RdRp level started to decline. Therefore, it is suggested that BMx inhibited the viral RNA synthesis by interaction with viral RdRp, and redistributed RdRp to perinuclear area for degradation.

Design of two-dimensional tunable photonic crystals with multiple functionalities

Negative refraction is an interesting phenomenon which can provide sub-wavelength imaging and a novel way to control the propagation path of photons. Photonic crystals have been intensively researched to achieve negative refraction. In this article, we present design and simulations of a new two-dimensional tunable photonic crystal obtained using the plane wave expansion method. The newly designed photonic crystals exhibit tunability among positive, zero, and negative refractions, when liquid crystals infiltrated in the structures are electrically tuned. The equifrequency surface diagrams of the designed photonic crystal unveil the refraction direction of photons in the structures. The tunability is further confirmed using the finite-difference time-domain simulation.

Laser induced selective removal of metallic carbon nanotubes

Distinguishing between carbon nanotubes (CNTs) according to their individual electronic properties is of significant importance for developing CNT-based electronics and devices. In this study, selective removal of metallic CNTs from CNT mixtures on silicon substrates was investigated using controlled laser irradiation. Free electron movement and eddy currents are induced within the metallic CNTs by the strong electric field and optical near-field effects caused by the laser irradiation. Selective heating of metallic CNTs in air results in selective removal of metallic CNTs when the laser fluence and wavelength are properly selected. Through this process, metallic nanotubes are successfully removed from the CNT mixtures. This technique provides an efficient single-step approach for selective removal of metallic CNTs from CNT mixtures.

[Detection of early organ dysfunction for the selection of treatment strategy on severe acute pancreatitis.]

OBJECTIVE

To investigate the severity related influencing factor and treatment strategy of severe acute pancreatitis with early organ dysfunction.

METHODS

From July 2007 to December 2008, 167 patients with severe acute pancreatitis were treated in the Surgical Department of Ruijin Hospital. The relationships between the happening of early organ dysfunction and outcome of the patients were observed, with operative or nonoperative treatment strategy.

RESULTS

Among 167 patients, 68 patients have early organ dysfunction, in which 39 with single organ dysfunction and 29 with multiple organ dysfunction. The early organ dysfunction were involved in 47.1% in cardiovascular system, 35.3% in lung and 29.4% in kidney. Aging (P < 0.05) and higher APACHE II score (P < 0.05) predicted a poor prognosis, which were benefit from early operation.

CONCLUSIONS

The mortality of the patients with SAP is related to age, and the degree of organ dysfunction as well. In the first phase of the disease, the selection of operation depends on the trends and the degree of early organ dysfunction before infected necrosis happens, with the aid of SOFA score as a scale.

Identifying individual n- and p-type ZnO nanowires by the output voltage sign of piezoelectric nanogenerator

Based on a comparative study between the piezoelectric outputs of n-type nanowires (NWs) and n-core/p-shell NWs along with the previous study (Lu et al 2009 Nano. Lett. 9 1223), we demonstrate a one-step technique for identifying the conductivity type of individual ZnO nanowires (NWs) based on the output of a piezoelectric nanogenerator without destroying the sample. A negative piezoelectric output voltage indicates an NW is n-type and it appears after the tip scans across the center of the NW, while a positive output voltage reveals p-type conductivity and it appears before the tip scans across the central line of the NW. This atomic force microscopy based technique is reliable for statistically mapping the majority carrier type in ZnO NWs arrays. The technique may also be applied to other wurtzite semiconductors, such as GaN, CdS and ZnS.

Detection of trace phosphorus in steel using laser-induced breakdown spectroscopy combined with laser-induced fluorescence

Monitoring of light-element concentration in steel is very important for quality assurance in the steel industry. In this work, detection in open air of trace phosphorus (P) in steel using laser-induced breakdown spectroscopy (LIBS) combined with laser-induced fluorescence (LIF) has been investigated. An optical parametric oscillator wavelength-tunable laser was used to resonantly excite the P atoms within plasma plumes generated by a Q-switched Nd:YAG laser. A set of steel samples with P concentrations from 3.9 to 720 parts in 10(6) (ppm) were analyzed using LIBS-LIF at wavelengths of 253.40 and 253.56 nm for resonant excitation of P atoms and fluorescence lines at wavelengths of 213.55 and 213.62 nm. The calibration curves were measured to determine the limit of detection for P in steel, which is estimated to be around 0.7 ppm. The results demonstrate the potential of LIBS-LIF to meet the requirements for on-line analyses in open air in the steel industry.

[Relationship between genetic polymorphisms of interferon-gamma gene intron 1 +874 site and recurrent Condyloma acuminata]

OBJECTIVE

To explore the relationship between the polymorphisms of interferon-gamma (IFN-gamma) gene intron 1 at position + 874 and Condyloma Acuminata (CA).

METHODS

IFN-gamma gene single nucleotide polymorphisms (intron 1 at position + 874) were detected in 156 subjects, including 76 patients with recurrent CA (CA group) and 80 healthy controls (control group), by polymerase chain reaction with sequence specific primers.

RESULTS

No significant difference of IFN-gamma 1 + 874 was found between CA group (TT, TA, and AA frequencies were 10.5%, 34.2%, and 55.3%, respectively) and control group (TT, TA, and AA frequencies were 7.5%, 30.0%, and 62.5%, respectively) (chi2 = 0.959, P = 0.619).

CONCLUSION

IFN-gamma gene polymorphism (intron 1 at position + 874) is not correlated with recurrent CA.

Self-aligned growth of single-walled carbon nanotubes using optical near-field effects

Self-aligned growth of ultra-short single-walled carbon nanotubes (SWNTs) was realized by utilizing optical near-field effects in a laser-assisted chemical vapor deposition (LCVD) process. By introducing the optical near-field effects, bridge structures containing single suspended SWNT channels were successfully fabricated through the LCVD process at a relatively low substrate temperature. Raman spectroscopy and I-V analyses have been carried out to characterize the SWNT-bridge structures. Numerical simulations using a high-frequency structure simulator revealed that significant enhancement of local heating occurs at metallic electrode tips under laser irradiation; it is about one order of magnitude higher than that in the rest of the electrodes. This technique suggests a novel approach to in situ low-temperature fabrication of SWNT-based devices in a precisely controlled manner, based on the nanoscale heating enhancement induced by the optical near-field effects.

Tip-enhanced near-field Raman spectroscopy with a scanning tunneling microscope and side-illumination optics

Conventional Raman spectroscopy (RS) suffers from low spatial resolution and low detection sensitivity due to the optical diffraction limit and small interaction cross sections. It has been reported that a highly localized and significantly enhanced electromagnetic field could be generated in the proximity of a metallic tip illuminated by a laser beam. In this study, a tip-enhanced RS system was developed to both improve the resolution and enhance the detection sensitivity using the tip-enhanced near-field effects. This instrument, by combining RS with a scanning tunneling microscope and side-illumination optics, demonstrated significant enhancement on both optical sensitivity and spatial resolution using either silver (Ag)-coated tungsten (W) tips or gold (Au) tips. The sensitivity improvement was verified by observing the enhancement effects on silicon (Si) substrates. Lateral resolution was verified to be below 100 nm by mapping Ag nanostructures. By deploying the depolarization technique, an apparent enhancement of 175% on Si substrates was achieved. Furthermore, the developed instrument features fast and reliable optical alignment, versatile sample adaptability, and effective suppression of far-field signals.

Detection of uranium in solids by using laser-induced breakdown spectroscopy combined with laser-induced fluorescence

Detection of uranium in solids by using laser-induced breakdown spectroscopy has been investigated in combination with laser-induced fluorescence. An optical parametric oscillator wavelength-tunable laser was used to resonantly excite the uranium atoms and ions within the plasma plumes generated by a Q-switched Nd:YAG laser. Both atomic and ionic lines can be selected to detect their fluorescence lines. A uranium concentration of 462 ppm in a glass sample can be detected by using this technique at an excitation wavelength of 385.96 nm for resonant excitation of U II and a fluorescence line wavelength of 409.0 nm from U II.

Broadband nanowire-grid polarizers in ultraviolet-visible-near-infrared regions

Broadband nanowire-grid polarizers were designed and numerically simulated using the finite difference time domain (FDTD) method. Using a broadband stimulation source, optical properties of the polarizers were analyzed in the ultraviolet (UV)-visible-near infrared (NIR) regions. Specifically, the extinction ratios and optical transmittances of transverse magnetic (TM) and transverse electric (TE) modes were characterized for different metal materials and geometrical parameters including wire-grid periods, metal-wire fill ratios, and spacing between wire-grid layers. Based on the simulation results, an extra broadband polarizer with an average extinction ratio higher than 70 dB and transmission efficiency over 64% in the range of 0.3 to 5 mum was proposed.

Effect of dietary cholesterol and fat levels on lipid peroxidation and the activities of antioxidant enzymes in rats

The aim of this study was to investigate the effect of dietary fat levels, with or without cholesterol, on lipid peroxidation and the activities of antioxidant enzymes in rats. Thirty-two Wistar rats aged 4 weeks were divided into 4 groups and fed high (20%; HF) or low (5%; LF) fat, with or without 1% cholesterol, for 6 weeks. Cholesterol feeding resulted in significantly higher concentrations of serum cholesterol, but lowered serum triacylglycerol levels. Cholesterol feeding also led to markedly decreased levels of hepatic thiobarbituric acid reactive substances (TBARS) and lower activities of hepatic superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase, and glucose-6-phosphate dehydrogenase (G6PDH) when compared with cholesterol-free counterparts in both HF and LF diets. On the other hand, rats fed high-fat diets showed increased serum and liver TBARS, but decreased hepatic GSH-Px, SOD, and G6PDH activities. Hepatic catalase activity was lower in rats fed cholesterol-containing diets, but higher in rats fed high-fat diets, and interaction existed between cholesterol and fat feeding. These results suggested that dietary cholesterol might delay lipid peroxidation and decrease the activities of the hepatic antioxidant enzymes. The degree of lipid peroxidation was also influenced by dietary fat levels.

SoRI 9409, a non-peptide opioid mu receptor agonist/delta receptor antagonist, fails to stimulate [35S]-GTP-gamma-S binding at cloned opioid receptors

Recent work suggests that opioids which combine mu agonist and delta antagonist activity may be non-addicting antinociceptive agents. SoRI 9409 (5'-(4-Chlorophenyl)-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5alpha-epoxypyrido-[2',3':6,7]morphinan) is a naltrexone-derived non-peptide ligand which demonstrates partial mu and kappa agonist activity and antagonist activity at delta receptors. Chronic administration of SoRI 9409 to mice failed to produce tolerance to its antinociceptive effect and SoRI 9409 produced less withdrawal signs than naloxone in acute and chronic morphine dependence models. To further characterize SoRI 9409 we determined its effects in the guanosine 5'-O-(3-[35S]thio)-triphosphate binding assay. SoRI 9409 demonstrated no agonist activity at cloned mu delta, or kappa receptors. Other experiments demonstrated that SoRI 9409 was a potent and selective delta antagonist (K(i) = 0.08 nM) which acted also as an antagonist at mu and kappa receptors. Its profile of activity resembled that of naltrindole (NTI). Viewed collectively, the in vitro data reported here predict that SoRI 9409 should be a mu antagonist in vivo, which is not observed. Resolving these discrepant findings will require additional research.

Opioid peptide receptor studies. 15. Relative efficacy of 4-[(N-allyl-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide and related compounds at the cloned human delta-opioid receptor

Previous data obtained from both binding and functional assays demonstrated that (-)-4-[(N-allyl-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide [(-)-RTI5989-54] displays selective binding and full agonist activity relative to (+/-)-RTI5989-54 for the delta opioid receptor. The present study was conducted to evaluate the activities of structurally diverse opioid receptor delta ligands in the [(35)S]GTP-gamma-S binding assay, comparing the relationship between receptor binding, activation, efficacy, and intrinsic efficacy. The data, obtained with cloned human delta receptors, demonstrated that (-)-RTI5989-54 behaves like the highly selective delta agonist SNC80. Addition of the hydroxyl group to RTI5989-54 (RTI5989-61) or replacement of the allyl group with the trans-crotyl group on the piperidine nitrogen of RTI-5989-61 (RTI5989-62) increased binding affinity, produced full agonist activity, and decreased intrinsic efficacy at the delta opioid receptor. The order of potency for the EC(50) (GTP-gamma-S) was RTI5989-62 (0.20 nM) > RTI5989-61 (0.43 nM) > SNC80 (1.92 nM) > DPDPE (3.50 nM) > (-)-RTI5989-54 (17.6 nM) > (+/-)-RTI5989-54 (65.6 nM) > (+)-RTI5989-54 (483 nM). RTI5989-61 and RTI5989-62 were fully efficacious, but had intrinsic efficacy values that were 2.2-3.1 times lower than that of DPDPE and SNC80. Comparison of the binding K(i) in competitively inhibiting [(125)I]IOXY binding to the functional K(i) for delta antagonists [Ki (IOXY)/Ki (GTP-gamma-S)] shows that antagonists might antagonize agonist-evoked neurochemical effects with equal magnitude while occupying different proportions of target receptors.

Canonical germinal center B cells may not dominate the memory response to antigenic challenge

Spleen and bone marrow (BM) are the major sites of antibody production and anamnestic response in systemically immunized mice. We examined the VDJ segment repertoire of antibody plaque-forming cells (APFC) in those two sites in the course of antibody responses to the hapten nitrophenyl (NP). Individual IgG APFC expressed any one of 10 V(H) segments of the V186.2/V3 (J558) gene family: 186.2, 102, 23, C1H4, 165.l, CH10, 3, 593.3, 24.8 and 671.5. The majority of cells in both spleen and BM expressed the V186.2 gene joined to a D segment with Tyr95. During a 2-month period after a single immunization, the V186.2(+) APFC in BM accumulated 3 times as many somatic mutations than splenic APFC (average 8.5 versus 3 mutations/V(H)); this process was T(h) dependent as shown by in vivo depletion of CD4(+) lymphocytes. However, the V186.2(+) APFC in both spleen and BM shared a recurrent W33L replacement, indicating their common origin from germinal centers. The APFC expressing the other (analogue) V(H) segments were evenly represented in the spleen and BM, but they accumulated few, if any, mutations. The anamnestic V186.2(+) APFC were highly mutated both in the spleen and BM; they represented a new and unexpected clonotype. The V/D segments were joined by Gly95 instead of Tyr95, the W33L was absent and a new shared K58R replacement appeared. The APFC expressing the 'analogue' V(H) genes comprised approximately 20% of the anamnestic response and did not accumulate more mutations, but their affinities were in the range of the memory V186.2(+) cells. These data suggest that the late primary and secondary responses to a hapten may be born by different B cell lineages, and that some clonotypes may reach the memory pool without an extensive mutation and expansion.

[Co-integration of BLG-LAtPA and WAP improved the expression of LAtPA in transgenic mouse milk]

In order to improve the expression of longer acting tissue plasminogen activator in the mammary epithelium of transgenic mice, the fragment of BLG-LAtPA hydrid gene was microinjected into mouse embryos with mice whey acid protein gene. Three mouse were tested as being Co-integration of BLG-LAtPA and WAP transgene by PCR and Southern blot. Milk obtained from lactating females contains biologically active tPA, and the concentration of tPA was calculated to be about 10 micrograms/mL.

[Cloning cDNA of extracellular domain of human erythropoietin receptor and its expression in Escherichia coli]

Human erythropoietin receptor (hEpoR) plays an important role in regulating the red blood cell production by promoting the proliferation and differentiation of RBC from erythroid precursors. hEpoR is a transmembrane protein, and its extrocellular domain (sEpoR) is of great importance in Epo signal transduction pathway. We cloned the gene of sEpoR by RT-PCR from the total RNA of human fetal liver and expressed it in E. coli after insertion of the gene in the expression vector pBV220. The cloned gene was confirmed by sequencing analysis and gene product was confirmed by both Western blot and its first 11 amino acid residues sequence of the N-terminal. In vitro bioassay showed that the purified gene product can repress the growth of TF-cells in the presence of Epo.

[Cloning of human G-CSF genomic gene and its expression in transgenic mice mammary gland]

Human genomic DNA was used as template of PCR. 1.5 kb G-CSF genomic DNA was obtained using PCR amplification method. Sequence analysis showed that genomic DNA sequence of human G-CSF was correct. The vector of mammary gland expression was constructed and contained whey acid protein (WAP) 5' control region directed human G-CSF genomic DNA. In order to produce transgenic mice, 1200 fertilized eggs were microninjected using WAP-G-CSF fragment. Two male transgenic mice were obtained and identified using PCR method and Southern analysis. Integration rate of human G-CSF gene was 2.37% in mice. Foreign gene could also be identified in F1 and F2 transgenic mice. Expression levels of human G-CSF in transgenic mouse milk were 120-250 ng/ml.

Nitric oxide signaling contributes to late-phase LTP and CREB phosphorylation in the hippocampus

Long-term potentiation (LTP) in the hippocampus has an early phase (E-LTP) that can be induced by one- or two-train tetanization, lasts approximately 1 hr, and is cAMP-dependent protein kinase (PKA) and protein synthesis independent and a late phase (L-LTP) that can be induced by three- or four-train tetanization, lasts >3 hr, and is reduced by inhibitors of PKA and of protein or RNA synthesis. Nitric oxide (NO) is thought to be involved in E-LTP, but until now there has been no information about the role of the NO-signaling pathway in L-LTP. We examined this question at the Schaffer collateral-CA1 synapses in slices of mouse hippocampus. An inhibitor of NO synthase blocked L-LTP induced by three-train tetanization and reduced L-LTP induced by four-train tetanization, whereas an inhibitor of PKA was more effective in blocking four-train L-LTP than three-train L-LTP. Three-train L-LTP was also blocked by inhibitors of guanylyl cyclase or cGMP-dependent protein kinase (PKG). Conversely, either NO or cGMP analogs paired with one-train tetanization produced late-phase potentiation, and the cGMP-induced potentiation was blocked by inhibitors of protein or RNA synthesis and an inhibitor of PKG, but not by an inhibitor of PKA. To test a possible downstream target of PKG, we examined changes in phospho-CRE-binding protein (phospho-CREB) immunofluorescence in the CA1 cell body area and obtained results similar to those of the electrophysiology experiments. These results suggest that NO contributes to L-LTP by stimulating guanylyl cyclase and cGMP-dependent protein kinase, which acts in parallel with PKA to increase phosphorylation of the transcription factor CREB.

Uncv (uncovered): a new mutation causing hairloss on mouse chromosome 11

A pair of mutant mice with a first sparse coat appeared spontaneously in the production stock of BALB/c mice with a normal coat. After being sib-mated, they produced three phenotypes in their progeny: mice with normal hair, mice with a first sparse coat and then a fuzzy coat, and uncovered mice. Genetic studies revealed the mutants had inherited an autosomal monogene that was semi-dominant. By using 11 biochemical loci--Idh, Car2, Mup1, Pgm1, Hbb, Es1, Es10, Gdc, Ce2, Mod1 and Es3--as genetic markers, two-point linkage tests were made. The results showed the gene was assigned to chromosome 11. The result of a three-point test with Es3 and D11Mit8 (microsatellite DNA) as markers showed that the mutation was linked to Es3 with the recombination fraction 7.89 +/- 2.19%, and linked to D11Mit8 with the recombination fraction 26.30 +/- 3.57%. The recombination fraction between Es3 and D11Mit8 was 32.90 +/- 3.81%. It is suggested that the mutation is a new genetic locus that affected the skin and hair structure of the mouse. The mutation was named uncovered, with the symbol Uncv. Further studies showed the mutation affected not only the histology of skin and hair but also the growth and reproductive performance of the mice. The molecular characterization of the Uncv locus needs to be further studied.

Age-related defects in spatial memory are correlated with defects in the late phase of hippocampal long-term potentiation in vitro and are attenuated by drugs that enhance the cAMP signaling pathway

To study the physiological and molecular mechanisms of age-related memory loss, we assessed spatial memory in C57BL/B6 mice from different age cohorts and then measured in vitro the late phase of hippocampal long-term potentiation (L-LTP). Most young mice acquired the spatial task, whereas only a minority of aged mice did. Aged mice not only made significantly more errors but also exhibited greater individual differences. Slices from the hippocampus of aged mice exhibited significantly reduced L-LTP, and this was significantly and negatively correlated with errors in memory. Because L-LTP depends on cAMP activation, we examined whether drugs that enhanced cAMP would attenuate the L-LTP and memory defects. Both dopamine D1/D5 receptor agonists, which are positively coupled to adenylyl cyclase, and a cAMP phosphodiesterase inhibitor ameliorated the physiological as well as the memory defects, consistent with the idea that a cAMP-protein kinase A-dependent signaling pathway is defective in age-related spatial memory loss.

Opioid peptide receptor studies, 11: involvement of Tyr148, Trp318 and His319 of the rat mu-opioid receptor in binding of mu-selective ligands

Previous data obtained with the cloned rat mu opioid receptor demonstrated that the "super-potent" opiates, ohmefentanyl (RTI-4614-4) and its four enantiomers, differ in binding affinity, potency, efficacy, and intrinsic efficacy. Molecular modeling (Tang et al., 1996) of fentanyl derivatives binding to the mu receptor suggests that Asp147, Tyr148, Trp318, and His319 are important residues for binding. According to this model, Asp147 interacts with the positively charged opiate agonist to form potent electrostatic and hydrogen-bonding interactions. In this study, the role of weak electrostatic and hydrogen-bonding "pi-pi" interactions of the O atom of the carbonyl group and the phenyl ring structures of RTI-4614-4 and its four enantiomers with residues Tyr148, Trp318, and His319 were explored via site-directed mutagenesis. Tyr148 (in transmembrane helix 3 {TMH3}), Trp318 (TMH7), and His319 (TMH7) were individually replaced with phenylalanine or alanine. Receptors transiently expressed in COS-7 cells were labeled with [125I]IOXY according to published procedures. Mutation of Tyr148 to phenylalanine reduced the binding affinities of some mu-selective agonists (2-7 fold) but did not alter the affinities of DAMGO, naloxone, and the non-selective opiates etorphine and buprenorphine. In contrast, this mutation significantly increased the binding affinities (decreased the Kd values) of [D-Ala2,D-Leu5]enkephalin, IOXY, and dermorphin. Mutation of Trp318 decreased opioid receptor binding to almost undetectable levels. Substitution of alanine for His319 significantly reduced binding affinities for the opioid ligands tested (1.3- to 48-fold), but did not alter the affinities of naloxone and bremazocine. These results indicate the importance of Tyrl48 and His319 for the binding of fentanyl derivatives to the mu receptor. Functional studies using the mutant receptors will provide additional insight into the mechanism of action of RTI-4614-4 and its four enantiomers.

Enhanced synaptic transmission and reduced threshold for LTP induction in fyn-transgenic mice

To elucidate the physiological role of Fyn, we analysed the properties of synaptic transmission and synaptic plasticity in hippocampal slices of mice overexpressing either wild-type Fyn (w-Fyn) or its constitutively active mutant (m-Fyn). These fyn-transgenes were driven by the calcium/calmodulin-dependent protein kinase II alpha promoter which turned on in the forebrain neurons including hippocampal pyramidal cells and in late neural development. In the hippocampal slices expressing m-Fyn the paired-pulse facilitation was reduced and the basal synaptic transmission was enhanced. A weak theta-burst stimulation, which was subthreshold for the induction of long-term potentiation (LTP) in control slices, elicited LTP in CA1 region of the slices expressing m-Fyn. When a relatively strong stimulation was applied, the magnitude of LTP in m-Fyn slices was similar to that in control slices. By contrast, the basal synaptic transmission and the threshold for the induction of LTP were not altered in the slices overexpressing wild-type Fyn. To examine the effect of expression of m-Fyn on GABAergic inhibitory system, we applied bicuculline, a GABAA receptor blocker, to the hippocampal slices. The ability of bicuculline to enhance excitatory postsynaptic potentials was attenuated in slices expressing m-Fyn, suggesting that the overexpression of m-Fyn reduced the GABAergic inhibition. The enhancement of synaptic transmission and the reduction of GABAergic inhibition may contribute to the enhanced seizure susceptibility in the mice expressing m-Fyn. Thus, these results suggest that regulation of Fyn tyrosine kinase activity is important for both synaptic transmission and plasticity.

[Studies of foreign gene integeation during embryo early development]

There are still some problems in transgenic animals. Gene transfer, for example, reamins a difficult and costly task for animals, the vectors carrying the gene coding for the proteins of interest are of unpredictable efficiency. Therefore, it is important to identify foreign gene integration in genomose before transferring fertilized eggs to receptors, in order to increase efficiency of producing transgenic animal. In this paper, the construct that mice whey acid protein (WAP) gene promoter directs G-CSF gene was used to microinject fertilized eggs of mice. Fertilized eggs containing foreign gene were measured by using PCR method. The results showed that 100%, 77.7% and 44.4% retentions of foreign gene were achieved in 1, 2 and 8 cell-stage, respectively. Two part homologous recombination fragments were constructed and coinjected in to fertilized eggs of mice. PCR amplification fragment went beyond this homologous recombination area. If foreign gene could not integrate in to genomose, the fragment of PCR amplification could not be produced during embryo development. The results showed that the rationes of foreign gene integrated in to genomoes in 1, 2 and 8 cell-stage were 11.1%, 55.5% and 44.4%, respectively. This method might provide us a way to screen transgenic eggs when we use embryo section technique in farm animal.

An immunosuppressant, FK506, protects against neuronal dysfunction and death but has no effect on electrographic and behavioral activities induced by systemic kainate

Kainate is a potent agonist of an excitatory amino acid receptor subtype in the central nervous system, and causes neuronal death in several regions of the brain. Neurons are preferentially killed in the hippocampus, especially in the CA1 region, by systemic administration of kainate. It is speculated that functional alterations occur in the neurons preceding death. We examined the effect of FK506 on kainate-induced neuronal death and functional alterations in the rat hippocampal CA1 region. FK506 had no effect on electrographic and behavioral seizure activities induced by kainate; however, it prevented neuronal death measured seven days after administration. Although neither death nor morphological alterations of neurons were observed in the CA1 region 24 h after administration, the neurons exhibited decreased excitatory postsynaptic potentials and enhanced long-term potentiation. This functional alteration was not detected in the rats administered FK506 prior to kainate. Taken together, these observations indicate that functional alteration precedes neuronal death in rats systemically administered kainate and that FK506 prevents both. It is suggested that FK506 exerts its neuroprotective effect not by attenuating electrographic and behavioral seizure activities, but by protecting neurons from kainate-induced functional disorders.