The class II major histocompatibility antigens, I-A and I-E, have been detected on the surface of certain immunocompetent cells, including B lymphocytes and monocytes. These molecules are involved in ...cell-cell interactions in the immune responses. Each class II antigen consists of two subunits, alpha and beta chains, and the genes encoding these subunits have been well characterized at the molecular level. To analyse the regulatory mechanism of E alpha gene expression and the role of the I-E antigen in the regulation of the immune responses, we have produced transgenic mice by microinjecting cloned Ed alpha genes into fertilized eggs of C57BL/6 mice of b haplotype. This strain of mouse carries a deletion in the upstream (5') region of the E alpha gene covering the transcriptional promoter and, therefore, does not express this gene. Interestingly, this genetic defect of the E alpha gene is accompanied by the inability of the host mouse to respond to a certain set of antigens, phenomena generally termed Ir gene control. We report here that the Ed alpha genes are expressed in these transgenic mice to form the I-Ed alpha Eb beta antigen on the surface of B lymphocytes and monocytes and that these I-E antigens are functional in terms of the induction of a mixed lymphocyte reaction and the restoration of immune responsiveness to poly(L-glutamic acid-L-lysine-L-phenylalanine) (GL-Phe).
In vitro effects of CCA, an anti-arthritis agent, were studied upon autologous mixed lymphocyte reaction (AMLR), lymphocyte mitogenesis, IL 1 and IL 2 production, immunoglobulin production and ...gamma-interferon (IFN) production. CCA at 50 micrograms/ml, which was not toxic to cells, blocked AMLR, IL 1 production and immunoglobulin production (IgM and IgG) significantly, while CCA at the same dose did not affect IL 2 production and lymphocyte mitogenic responses to Staphylococcus aureus Cowan I(SAC) and pokeweed mitogen(PWM). CCA at both 20 ng/ml and 20 micrograms/ml induced human gamma/IFN. Addition of IL 1 and/or IL 2 reversed inhibitory effect of CCA on AMLR. These data suggest that CCA exerts its actions by mainly affecting T cells and monocytes and can be used as an immunomodulator.
Transcription reaction by T7-RNA polymerase was photo-regulated on the basis of two strategies as depicted in Scheme 1. It was found that incorporation reaction of azobenzene-tethered uridine ...triphosphate proceeded only when azobenzene took trans-form (Scheme 1(A)). On the other hand, the transcription was more efficient when the azobenzene moiety, tethered to the non-template strand of the promoter DNA, was in its cis-form under UV irradiation (Scheme 1(B)). Thus, azobenzene-tethered DNAs are promising for the photo-regulation of gene-expression.
The behavior of a silver-silver oxide electrode in KOH solution containing a small amount of cesium hydroxide was investigated by the potentiostatic and galvanostatic methods as well as by an ...observation using a scanning electron microscope and an X-ray diffraction. The following results were obtained. ( 1 ) The coulombic areas under all the peaks in the cyclic voltammograms increased by the addition of cesium hydroxide. ( 2 ) The charge and, discharge capacity, of the electrode measured by the galvanostatic method was obviouslyin, creased by the addition of cesium hydroxide. The electrode cdpacity. determined from tfie charge-discharge curves and the current-potential curves increased in the presence of cesium hydroxide. Consequently, cesium hydroxide 1×10-2 mol/l (4.7 mol/l KOH) solution was more effective than the solution of other concentrations. ( 3 ) It was observed by an electronmicroscope that the active materials of the electrode grew to be big porous crystals or needlelike complex crystals in the presence of cesium hydroxide. The increase in the electrode capacity caused by the addition of the hydroxide seems to be due to the formation of such complex crystaljites. It has been concluded that the behavior of the electrode can be explained as the adsorption phenomenon of Cs+ ions from the added cesium hydroxide during the charge and discharge cycles.
A series of unnatural base pairs was designed and examined for the expansion of the genetic alphabet and for a better understanding of the mechanism of nucleic acid biosyntheses. To improve the shape ...complementarity of the previously developed unnatural base pairs, 2-amino-6-(N,N-dimethylamino)purine (x)--pyridon-2-one (y) and 2-amino-6-(2-thienyl)purine (s)--y, the pyrimidine analogue, y, was replaced by a five-member ring, 4-imidazolin-2-one (z), and the s-z pairing in replication was examined. Unnatural bases based on the five-member ring were also applied to the development of non-hydrogen-bonded base pairs.
Lateral p-i-n diodes with small i-region width (less than <inline-formula> <tex-math notation="LaTeX">5 ~\mu \text{m} </tex-math></inline-formula>) were fabricated by direct ion implantation into a ...high-purity semi-insulating silicon carbide (SiC) substrate. The breakdown voltage of the diodes increased with increasing the i-region width and a lateral effective breakdown electric field of 1.7-1.9 MV/cm was obtained. The experimental breakdown voltage well agreed with the technology computer-aided design (TCAD) simulation, indicating that deep levels contributing the semi-insulating property do not seriously deteriorate the breakdown voltage in case of the small i-region width.
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