Lobenzarit disodium (CCA) inhibits in vitro immunoglobulin production via direct interaction with B lymphocytes.

The regulatory effects of lobenzarit disodium (CCA), a therapeutic agent for treating rheumatoid arthritis (RA), on polyclonal immunoglobulin production by human lymphocytes were investigated in vitro. CCA inhibited the production of immunoglobulin in all the classes examined at a clinically relevant concentration. Moreover, it inhibited the immunoglobulin production as well as lymphocyte proliferation even when purified B lymphocytes preactivated by Staphylococcus aureus COWAN I were cultured with recombinant lymphokines such as IL2 and IL6. These results suggest that CCA acts directly on B lymphocytes. The analysis at each of two different stages of B lymphocyte activation lineage, i.e., the primary activation stage and a stage of proliferation and differentiation to antibody secreting cells, has indicated that CCA inhibits the proliferation-differentiation stage of B lymphocytes. CCA does not inhibit B lymphocytes at the primary activation stage; actually, it augments them, resulting in the subsequent enhancement of immunoglobulin production.     

Multi-quasiparticle excitations in ~(145)Tb

Nuclei with N and Z near magic number can be well described by the nuclear shell model. The 145Tb nucleus has a valence proton and a pair of neutron holes with respect to the doubly closed 146Gd nucleus. Therefore, it is expected that the excitations in 145Tb be dominated by single-particle configurations. A detailed measurement of the excitation scheme in 145Tb would give us an opportunity to examine the behavior of multi-particle excitations involving high angular momentum orbits and provi…     

Characteristic changes in the fluorescence spectra of 1-naphthol at the gelation point during the sol-gel-xerogel transitions

The fluorescence spectra of 1-naphthol were observed during the sol-gel-xerogel transitions of two different systems as a function of time; one is in the silicon and titanium (Si:Ti = 4500:1) binary systems involving no catalysts and the silicon and lithium (Si:Li = 99:1) binary systems involving HC1 as the catalyst. During the first stage of the sol-gel reaction of the 1-naphthol system, the fluorescence spectra mainly originated from the broad ’L₂ state. The fluorescence spectrum originating from the anionic species at around 470 nm increased as the reaction proceeded. It was found that the fluorescence spectra originating from the anionic species of 1-naphthol drastically decreased in both systems just after gelation. These findings indicate that it becomes difficult for the dissociation of the excited state of 1-naphthol to give a dissociative proton to the surrounding matrix. The fluorescence-excitation spectra for the Si/Ti system indicated that the main route for the excited state of 1-naphthol to form a dissociative proton is through the excited state of the contact ion pair, while the main route in the Si/Li system is via the direct excitation of the neutral 1-naphthol and its dissociation. The observed changes in the fluorescence spectra of 1-naphthol in these sol-gel systems provide a sensitive means to monitor changes during the sol-gel transition process.     

Primary cultures of chick osteocytes retain functional gap junctions between osteocytes and between osteocytes and osteoblasts.

The inaccessibility of osteocytes due to their embedment in the calcified bone matrix in vivo has precluded direct demonstration that osteocytes use gap junctions as a means of intercellular communication. In this article, we report successfully isolating primary cultures of osteocytes from chick calvaria, and, using anti-connexin 43 immunocytochemistry, demonstrate gap junction distribution to be comparable to that found in vivo. Next, we demonstrate the functionality of the gap junctions by (1) dye coupling studies that showed the spread of microinjected Lucifer Yellow from osteoblast to osteocyte and between adjacent osteocytes and (2) analysis of fluorescence replacement after photobleaching (FRAP), in which photobleaching of cells loaded with a membrane-permeable dye resulted in rapid recovery of fluorescence into the photobleached osteocyte, within 5 min postbleaching. This FRAP effect did not occur when cells were treated with a gap junction blocker (18alpha-glycyrrhetinic acid), but replacement of fluorescence into the photobleached cell resumed when it was removed. These studies demonstrate that gap junctions are responsible for intercellular communication between adjacent osteocytes and between osteoblasts and osteocytes. This role is consistent with the ability of osteocytes to respond to and transmit signals over long distances while embedded in a calcified matrix.     

Adsorption voltammetry of the copper(II) 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex

The voltammetric determination of copper(II), based on adsorptive accumulation of the Cu(II)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (S-Br-PADAP) complex on a hanging mercury drop electrode, is reported. The complex can be accumulated at the electrode at constant potential in 0.1M ammonium nitrate/ammonia buffer solution, and its reduction wave observed by scanning the potential in the negative direction, in the differential pulse mode. The calibration graph for copper is linear over the range 0.05-0.5muM, with accumulation for 5 min at -0.20 V. The adsorption of the complex is discussed and compared with that of copper complexes with several other pyridylazo derivatives.     

Substitution and elimination reactions of poly(epichlorohydrin) and poly(2-chloroethyl vinyl ether) using phase transfer catalysis

The reactions of poly(epichlorohydrin) (PECH) and poly(2-chloroethyl vinyl ether) (PCEVE) with various reagents were investigated using phase transfer catalyst (PTC) such as tetra-n-butylammonium bromide (TBAB), 18-crown-6 (CR6), and dicyclohexyl-18-crown-6 (DCHC) is a solid—liquid two-phase system. Although the reactions of these polymers hardly occurred without PTC in nonpolar solvents such as toluene and diglyme under mild conditions, the addition of PTC caused the reactions to proceed smoothly under the same conditions. In addition, the reactions of PECH and PCEVE with a strong base such as potassium hydroxide proceeded selectively through β-elimination reaction to produce the polymers with pendant vinyl groups. These results suggested this method is useful for the syntheses of functional polymers. On the other hand, it turned out that quaternary ammonium salts such as TBAB have higher catalytic activity than crown ethers such as CRG and DCHE in these reactions. Furthermore, the catalytic activity of quaternary ammonium salts was strongly influenced by their chain length and the structure of the polymers.     

Role of stress in the self-limiting oxidation of copper nanoparticles

The oxidation process of Cu nanoparticles has been investigated by means of an in-situ X-ray diffraction method. A self-limiting oxidation process involving an unusually drastic decrease (about 4 orders in magnitude) in the oxidation rate was observed at 298 K, whereas a non-self-limiting oxidation emerged at 323 K with a rate of at least 4 orders in magnitude faster than 298 K. The drastic slowing at 298 K and the big differences between the two close temperatures in the oxidation kinetics were found to be directly correlated to whether the compressive stress in the Cu(2)O(111) layers that commensurately formed on the Cu(111) surface is relaxed or not.