Practical model for gas temperature effects on CO2lasers

An analytical and experimental investigation on the effect of gas temperature on convection flow CO₂ lasers is presented. A simple and practical model neglecting the population of lower laser levels is proposed and examined by experiments. The model indicates simply that the gas temperature affects the `inherent threshold discharge power'. Appropriateness of the model has been proven regardless of the schemes of cross flow or axial flow     

Inhibitory effect of melanin pigment on sensitization and elicitation of murine contact photosensitivity: mechanism of low responsiveness in C57BL/10 background mice

We have shown that murine contact photosensitivity (CPS) to 3,3',4',5-tetrachlorosalicylanilide (TCSA) is genetically controlled mainly by the major histocompatibility complex. The H-2b,d haplotypes are closely associated with high responders, whereas mice with the H-2k are non-responders. Irrespective of their H-2 haplotypes, the C57BL/10 (B10) background strains, including B10, B10.D2, B10.A, and B10.BR, possessing black fur color, were low or nonresponders in CPS to TCSA. In B10 mice, however, high-sensitivity responses were induced when subcutaneous inoculation of epidermal cells (ECs) photomodified in vitro with TCSA was used for both immunization and challenge, suggesting that the epicutaneous route for induction and elicitation is defective in B10 background mice. F1 mice obtained by crossing high-responder BALB/c and low-responder B10 mice, possessing agouti fur color, were non-responders of CPS. The magnitude of CPS in the F2 mice derived from F1 (BALB/c X B10) siblings varied from low to high. When these F2 mice were divided into five groups with regard to fur color, the magnitude of reaction was correlated with the fur color and there was inverse relationship between the magnitude of CPS and the amount of melanin pigment in earlobe ECs. Furthermore, the in vivo formation of TCSA-EC photoadducts was negatively correlated to the melanin amount in earlobes. These observations suggested that the failure in CPS of the B10 background mice stems from inability of in vivo photocoupling of TCSA to ECs, presumably due to absorption of ultraviolet radiation by melanin pigment.     

Cytokine-secreting cells in relapsing multiple sclerosis patients treated with high-dose intravenous methylprednisolone]

Domon L, a heat-treated component of gram-negative bacterium Achromobacter stenohalis, is used for the treatment of infectious diseases of animals. Here, we investigated the immunopotentiating potential of Domon L. In vitro studies showed that Domon L enhanced nitric oxide (NO) formation from murine macrophage RAW264.7 cells in concert with interferon (IFN)-gamma. The effect of Domon L on NF-kappaB activation was investigated, in order to understand the molecular mechanisms of enhanced NO formation by Domon L. Domon L induced translocation of NF-kappaB to the nucleus in RAW264.7 cells. Induction of NF-kappaB dependent gene expression by Domon L was further confirmed using a transfectant containing an NF-kappaB-luciferase reporter gene. In vivo injection of Domon L elevated both serum IL-6 and mucoprotein, whose gene expression is partly under the control of NF-kappaB. The spleen cells of rats treated with Domon L produced much more NO when stimulated with LPS + IFN gamma than spleen cells of untreated rats. These results suggest that Domon L acts as an anti-infectious agent via NF-kappaB activation.     

Induced excitation and synchronization of nerve impulses in two parallel unmyelinated fibers

The interaction of nerve impulses in two adjacent fibers has been treated quantitatively. Calculations were made on the basis of equations describing the propagation of impulses in electrically equivalent parallel transmission lines that contain the active membrane current elements proposed by Hodgkin and Huxley. The coupling between adjacent fibers is simulated by a resistive network. The effects of coupling appear to be as follows: while an impulse is traveling along one fiber, a change in the excitability of the other develops, and it has also been confirmed that, in the special case of strongly coupled fibers, excitation of the parallel fiber can be induced by the active one. In the case of parallel conduction of impulses in each fiber, synchronization of their conduction velocities becomes apparent when the inherent velocities of the impulses differ by not more than 20 percent. In general, the closer fibers approach one another and/or the greater the resistance of the interstitial fluid, the stronger is the apparent effect of interaction between impulses. The results of the present simulation are compared with the experimental observation by Katz and Schmitt.     

Efficient production of Cre-mediated site-directed recombinants through the utilization of the puromycin resistance gene, pac: a transient gene-integration marker for ES cells

Gene targeting in embryonic stem (ES) cells is a powerful tool for generating mice carrying specifically designed mutations in the germline. Puromycin can completely kill ES cells within 24 to 48 h whereas G418 and hygromycin cannot. We have, therefore, proposed that the puromycin N-acetyltransferase ( pac ) gene, may be utilized as a transient gene-integration marker. Using a circular expression vector of cre and pac genes, Cre-mediated mutant cells were effectively enriched by pulse treatment of puromycin without stable integration of their genes. We have thus demonstrated the first application of pac as a transient gene-integration marker for ES cells.     

Cis- and trans-linalool 3,7-oxides and methyl salicylate glycosides and (Z)-3-hexenyl beta-D-glucopyranoside as aroma precursors from tea leaves for oolong tea

Two new alcoholic aroma precursors, cis- and trans-linalool, 3,7-oxides 6-O-beta-D-apiofuranosyl-beta-D-glucopyranosides (1 and 2), as well as two already known compounds, (Z)-3-hexenyl beta-D-glucopyranoside (3) and methyl salicylate 6-O-beta-D-xylopyranosyl-beta-D-glucopyranoside (beta-primeveroside: 4), and another new monoterpendiol glycoside, 8-hydroxygeranyl beta-primeveroside (5) have recently been isolated as aroma precursors in tea leaves (Camellia sinensis var. sinensis cv. Maoxie) ready for oolong tea processing.     

Beam deflection in a transverse-flow gas laser

The beam deflection phenomenon of a transverse-flow discharge-excited CO₂ gas laser is studied by measuring the beam pattern with the rotating-wire method at gas velocities of 35-70 m/s, gas pressures of 5.3-10.6 kPa (10³ N/m²), and laser powers of 50-700 W. The beam deflection distance increased with increasing laser power and gas pressure and with decreasing gas velocity. All the data points of beam deflection distances observed experimentally fell on one line when normalized by the gas pressure and plotted against the measured temperature gradient in the resonator. It is shown that the most important factor affecting the beam deflection is the refractive index variation of the gas produced by the gas temperature gradient in the resonator. Methods to reduce the beam-deflection distances are suggested