Particle-bombardment-mediated DNA vaccination with rotavirus VP4 or VP7 induces high levels of serum rotavirus IgG but fails to protect mice against challenge

We recently reported that epidermal immunization using the PowderJet particle delivery device with plasmid vector pcDNA1/EDIM6 encoding rotavirus VP6 of murine strain EDIM induced high levels of serum rotavirus IgG but failed to protect mice against EDIM infection (Choi, A. H., Knowlton, D. R., McNeal, M. M., and Ward, R. L. (1997) Virology 232, 129-138.). This was extended to determine whether pcDNA1/EDIM4 or pcDNA1/EDIM7, which encode either rotavirus VP4 or VP7, the rotavirus neutralization proteins, could also induce rotavirus-specific antibody responses and if these responses resulted in protection. Titers of rotavirus serum IgG increased with the first dose in mice immunized with pcDNA1/EDIM7, but little or no serum rotavirus IgG was detected in mice immunized with pcDNA1/EDIM4. In vitro assays with these plasmids in rabbit reticulocyte lysates showed that VP4 was expressed but the amount was considerably lower than VP6 or VP7. To improve expression of VP4 and induction of rotavirus-specific humoral responses, the coding region of VP4 was cloned into the high-expression plasmid WRG7054 as a fusion protein containing the 22-amino-acid secretory signal peptide of tissue plasminogen activator (tPA) at its N terminus. In vitro expression of tPA::VP4 was significantly higher than unmodified VP4, and mice inoculated with WRG7054/EDIM4 generated high titers of rotavirus IgG. The coding sequence of VP7 without the first 162 nucleotides was also cloned into WRG7054, but no difference was observed between titers of serum rotavirus IgG in mice immunized with this plasmid (WRG7054/EDIM7Delta1-162) and pcDNA1/EDIM7. The rotavirus-specific IgG titers in all immune sera were predominantly IgG1 indicating induction of Th 2-type responses. None of the mice immunized with any of the VP4 or VP7 plasmids developed serum or fecal rotavirus IgA or neutralizing antibody to EDIM. When immunized mice were challenged with EDIM virus, there was no significant reduction in viral shedding relative to unimmunized controls. Therefore epidermal immunization with VP4 or VP7 alone elicited rotavirus IgG responses but did not protect against homologous rotavirus challenge.     

Solar/UV-induced photocatalytic degradation of three commercial textile dyes.

The photocatalytic degradation of three commercial textile dyes with different structure has been investigated using TiO(2) (Degussa P25) photocatalyst in aqueous solution under solar irradiation. Experiments were conducted to optimise various parameters viz. amount of catalyst, concentration of dye, pH and solar light intensity. Degradation of all the dyes were examined by using chemical oxygen demand (COD) method. The degradation efficiency of the three dyes is as follows: Reactive Yellow 17(RY17) > Reactive Red 2(RR2) > Reactive Blue 4 (RB4), respectively. The experimental results indicate that TiO(2) (Degussa P25) is the best catalyst in comparison with other commercial photocatalysts such as, TiO(2) (Merck), ZnO, ZrO(2), WO(3) and CdS. Though the UV irradiation can efficiently degrade the dyes, naturally abundant solar irradiation is also very effective in the mineralisation of dyes. The comparison between thin-film coating and aqueous slurry method reveals that slurry method is more efficient than coating but the problems of leaching and the requirement of separation can be avoided by using coating technique. These observations indicate that all the three dyes could be degraded completely at different time intervals. Hence, it may be a viable technique for the safe disposal of textile wastewater into the water streams.     

Ascorbic acid is a stimulatory cofactor for mitochondrial glycerol-3-phosphate dehydrogenase

We describe in this report a sensitive and direct method for the analysis of tamoxifen (TAM) in microsamples of plasma. The drug and internal standard (quinine bisulfate, I.S.) were separated on a 10-microm particle, 10 cm X 8 mm CN cartridge in conjunction with a radial compression system. The mobile phase was a mixture of 0.1 M sodium acetate in 0.001 M tetrabutylammonium phosphate solution (pH 6) and methanol (30:70, v/v) at a flow-rate of 4 ml/min. After addition of I.S. and o-phosphoric acid in acetonitrile (0.6 M) to the plasma (30 microl), the mixture was placed in an ultraviolet shortwave transluminator for 2 min prior to injection into the chromatograph. The compounds were detected in the effluent fluorometrically at excitation and emission wavelengths of 258 and 378 nm, respectively. Under these conditions, no interference in the assay from any endogenous substance or other concurrently used drugs was observed and the retention times of I.S. and TAM were 4.4 and 10.15 min, respectively. The concentration of TAM in plasma was linearly (r>0.9983) related to the peak height ratio (TAM/I.S.) in the range 0.01-2.0 microg ml(-1) and C.V. at 0.075, 0.4 and 1.2 microg ml(-1) was < or = 4.96%. We are currently using this assay for monitoring TAM in plasma and investigating its pharmacokinetics in cancer patients receiving cytotoxic drugs in addition to TAM as a multi-drug resistance modifier.     

Characterization of the cavity nucleation factor for life prediction under creep-fatigue interaction

It is understood that grain boundary cavitation is one of the detrimental processes for the degradation of materials that reduces the creep-fatigue life at high temperatures. In a previous investigation, a model for life prediction under creep-fatigue conditions was proposed in terms of cavity nucleation and growth. In that model, the cavity nucleation factor (P) was introduced to correlate between the number of cavities and the plastic strain range from which athermal vacancies are generated. It was considered to be a material specific constant which was independent of the experimental conditions. However, in this study, it is found that the cavity nucleation factor is a function of the plastic strain range but is independent of the testing temperature at near 0.5 T _m. In the light of this dependency, a new cavity nucleation factor (P'), is introduced. Using this new cavity nucleation factor (P'), a modified equation for life prediction is proposed, and it is shown that there is good agreement between predicted and experimental lives. Additionally, an interesting approach has been made to find the physical meaning of the new cavity nucleation factor (P'). According to this study, it is suggested that the new cavity nucleation factor, which is regarded as a material specific constant, is found to be strongly related to the density of the grain boundary precipitates with a linear relationship existing between them.     

Improved performances of a S-SEED using extremely shallowquantum-wells and asymmetric Fabry-Perot cavity structure

The authors report significantly improved performances of a symmetric self-electrooptic-effect device (S-SEED), with high on-off contrast ratio (>30:l) and large optical bistability loop widths (ΔP=44%) at an applied bias of V_a=0 V, i.e., with no power supply. The S-SEED is made of extremely shallow quantum wells (ESQWs) in an asymmetric Fabry-Perot (AFP) cavity structure. At V_a =5 V ΔP increased by up to 95%, preserving the high contrast ratio. The reflectivity changes at V_a=0 and 5 V were about 15% and 30%, respectively. These are believed to be the largest values ever reported for such structures     

Advantages of CDMA and spread spectrum techniques over FDMA andTDMA in cellular mobile radio applications

A unified theoretical method for the calculation of the radio capacity of multiple-access schemes such as FDMA (frequency-division multiple access), TDMA (time-division multiple access), CDMA (code-division multiple access) and SSMA (spread-spectrum multiple access) in noncellular and cellular mobile radio systems is presented for AWGN (additive white Gaussian noise) channels. The theoretical equivalence of all the considered multiple-access schemes is found. In a fading multipath environment, which is typical for mobile radio applications, there are significant differences between these multiple-access schemes. These differences are discussed in an illustrative manner revealing several advantages of CDMA and SSMA over FDMA and TDMA. Novel transmission and reception schemes called coherent multiple transmission and coherent multiple reception are briefly presented     

A neural network-based power system stabilizer using power flowcharacteristics

A neural network-based power system stabilizer (neuro-PSS) is designed for a generator connected to a multi-machine power system utilizing the nonlinear power flow dynamics. The use of power flow dynamics provides a PSS for a wide range of operation with reduced size neural networks. The neuro-PSS consists of two neural networks: neuro-identifier and neuro-controller. The low-frequency oscillation is modeled by the neuro-identifier using the power flow dynamics, then a generalized backpropagation-through-time (GBTT) algorithm is developed to train the neuro-controller. The simulation results show that the neuro-PSS designed in this paper performs well with good damping in a wide operation range compared with the conventional PSS