Current collecting efficiency of micro tubular SOFCs

In this study, current collecting efficiency of the micro tubular solid oxide fuel cell (SOFC) was estimated to determine optimum size of the micro tubular SOFC. Two models for collecting current from single terminal (ST) and double terminal (DT) of anode tube were proposed and used to calculate the current collecting efficiency as functions of anode thickness, tube length and operating temperature. It was shown that design of the cell geometry and current correcting method are significantly important to achieve high performance micro tubular SOFC stacks. The efficiency loss estimated from the DT model was about 2–4-fold lower than those of obtained from the ST model. The DT model was shown to be more effective for higher operating temperature and the tube length.     

Beta-thujaplicin zinc chelate induces apoptosis in mouse high metastatic melanoma B16BL6 cells

The cytotoxic effects of beta-thujaplicin and five kinds of metal chelates were examined on mouse melanoma B16BL6 cells by cell viability and lactate dehydrogenase (LDH) release assay. Beta-thujaplicin-zinc chelate and beta-thujaplicin-copper chelate had higher cytotoxic effects than beta-thujaplicin, and the 50% effective doses (ED50) of these metal chelates were 12.5 and 25 microM, respectively. In addition, the zinc chelate induced DNA ladder formation in B16BL6 cells, as shown by the DNA fragmentation assay, suggesting that cell death induced by the zinc chelate is apoptosis. The zinc chelate also had a cytotoxic effect and induced DNA fragmentation on other tumor cell lines: HeLa, Meth A, and B16F1 cells, but not on normal human diploid fibroblasts FS-4. These results suggest that beta-thujaplicin-zinc chelate induces apoptotic cell death in various tumor cell lines and is a potent antitumor agent for tumor cells including malignant melanomas.     

Lack of PPCA expression only partially coincides with lysosomal storage in galactosialidosis mice: indirect evidence for spatial requirement of the catalytic rather than the protective function of PPCA

Protective protein/cathepsin A (PPCA) is a pleiotropic lysosomal enzyme that complexes with beta-galactosidase and neuraminidase, and possesses serine carboxypeptidase activity. Its deficiency in man results in the neurodegenerative lysosomal storage disorder galactosialidosis (GS). The mouse model of this disease resembles the human early onset phenotype and results in severe nephropathy and ataxia. To understand better the pathophysiology of the disease, we compared the occurrence of lysosomal PPCA mRNA and protein in normal adult mouse tissues with the incidence of lysosomal storage in PPCA(-/-) mice. PPCA expression was markedly variable among different tissues. Most sites that produced both mRNA and protein at high levels in normal mice showed extensive and overt storage in the knockout mice. However, this correlation was not consistent as some cells that normally expressed high levels of PPCA were unaffected in their storage capability in the PPCA(-/-) mice. In addition, some normally low expressing cells accumulated large amounts of undegraded products in the GS mouse. This apparent discrepancy may reflect a requirement for the catalytic rather than the protective function of PPCA and/or the presence of cell-specific substrates in certain cell types. A detailed map showing the cellular distribution of PPCA in nomal mouse tissues as well as the sites of lysosomal storage in deficient mice is critical for accurate assessment of the effects of therapeutic interventions.     

Expression of recombinant human thyrotropin receptor in myeloma cells

Starting with a previously isolated cDNA for human thyrotropin receptor (TSHR), we established a transformed myeloma cell line, SP56, which expresses human TSHR on its cell surface. Binding analysis showed that SP56 bears 1.1 x 10(5) TSHR per cell with a Kd of 2.2 x 10(-10) M. Using the purified cellular membrane, we established a TSH binding inhibition immunoglobulin (TBII) assay for autoantibodies against TSHR. We compared it with the TBII assay utilizing porcine thyroid membranes expressing porcine TSHR, which has been widely used for TBII assay, by using 96 serum samples from patients with autoimmune thyroid disease and normal individuals. Our TBII assay was more sensitive than the one using porcine TSHR: of 38 sera of patients which were judged negative for autoantibodies to TSHR (TBII value below 10%) by the latter assay, 28 were positive (above 20%) in our assay. By using a perfusion culture system, we obtained as many as 3 x 10(10) SP56 cells, from which 3,450 mg protein of the membrane could be purified; this is sufficient for 15,000 assays. The results indicate that the membrane of the myeloma cell line SP56 is more suitable for use in the TBII assay than the porcine thyroid membrane, in terms of sensitivity to autoantibodies against TSHR in human sera.     

Experimental demonstration of soliton data transmission over unlimited distances with soliton control in time and frequency domains

A 2/sup 9/-1 pseudorandom-binary-sequence soliton signal has been transmitted experimentally over one million km for the first time with no degradation in the bit error rates. The synchronous modulator was driven by a timing clock signal extracted from the transmitting data signal. These results mean that it is possible to send soliton data signals over unlimited distances through the use of soliton control in the time and frequency domains.<>     

Surface alterations of the bovine oocyte and its investments during and after maturation and fertilization in vitro

Surface characteristics of the bovine oocyte and its investments before, during, and after maturation, and fertilization in vitro were evaluated by scanning electron microscopy (SEM). Oocyte diameters were also measured during SEM analysis of the oocyte. The cumulus cells manifested a compact structure with minimal intercellular spaces among them in the immature oocytes. These became fully expanded with increased intercellular spaces after maturation in vitro, but contracted again after fertilization. The zona pellucida (ZP) showed a fibrous, open mesh-like structure in the maturing and matured oocytes. The size and number of meshes on the ZP decreased dramatically after fertilization. The vitelline surface of immature oocytes was characterized by distribution of tongue-shaped protrusions (TSPs) varying in density. After 10 and 22 hr of maturation incubation, oocyte surface microvilli (MV) increased to become the predominant surface structure, and TSPs decreased substantially. The vitelline surface of fertilized oocytes (at 6 and 20 hr) was similar to that of the matured oocytes, but unfertilized oocytes had less dense MV than did fertilized oocytes (at 20 hr). The diameter of the oocytes decreased from 99 to 80 microns during maturation and increased to 106 microns after insemination (P < 0.05). Membrane maturation was characterized by surface changes from a TSP-predominant pattern to a MV-predominant pattern. Thus, the bovine oocyte maturation process was found to involve the expansion of cumulus cells and the maturation of the ZP, which changes dramatically upon fertilization. Also, volumetric changes occurred in ooplasm processed for SEM following oocyte maturation and insemination.     

A novel strategy of cell targeting based on tissue-specific expression of the ecotropic retrovirus receptor gene

Gene transfer into specific tissues or cell types is a key technique in the development of gene therapy. Modification of vector particles such that they selectively bind to the target cells has been attempted, but the limitation of this approach is the low transduction efficiency. Here, we show that a two-step gene transfer system can be used for efficient cell targeting. With this strategy, and using a high-titer adenoviral vector containing a tissue-specific promoter, we have engineered a system in which only target cells become susceptible to retrovirus-mediated transduction. In a model experiment, we constructed an adenoviral vector (Ad.AFPEcoRec) containing the ecotropic retrovirus receptor (EcoRec) gene under the control of the alpha-fetoprotein (AFP) promoter. A binding assay showed that after transduction with AD.AFPEcoRec, EcoRec molecules were efficiently expressed in AFP+HepG2 cells, but not in AFP-HeLa and AFP-HLE cells. The EcoRec-expressing HepG2 cells could be stably transduced with ecotropic retroviral vectors, whereas HeLa and HLE cells remained highly resistant to retrovirus-mediated gene transfer. The apparent titer on HepG2 cells was greater than 2 x 10(5) CFU/ml. Because various tissue-specific promoter/enhancer elements are available, the two-step system could be used as a general strategy for both ex vivo and in vivo targeted gene transfer.     

Optical Energy Gap and Below Gap Optical Absorption of Fullerene Films Measured by the Constant Photocurrent Method and Photothermal Deflection Spectroscopy

The CPM spectra of fullerene films was measured to obtain the below gap absorption. The optical energy gap E_o was obtained by using the Tauc's plots. E_o did not change greatly with intercalated impurities. The absorption due to intercalated impurities was found below 1.6eV.