In mammals, the environmental light/dark cycle strongly synchronizes the circadian clock within the suprachiasmatic nuclei (SCN) to 24 hr. It is well known that not only photic but also nonphotic stimuli can entrain the SCN clock. Actually, many studies have shown that a daytime injection of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH DPAT), a serotonin 1A/7 receptor agonist, as a nonphotic stimulus induces phase advances in hamster behavioral circadian rhythms in vivo, as well as the neuron activity rhythm of the SCN in vitro. Recent reports suggest that mammalian homologs of the Drosophila clock gene, Period (Per), are involved in photic entrainment. Therefore, we examined whether phase advances elicited by 8-OH DPAT were associated with a change of Period mRNA levels in the SCN. In this experiment, we cloned partial cDNAs encoding hamster Per1, Per2, and Per3 and observed both circadian oscillation and the light responsiveness of Period. Furthermore, we found that the inhibitory effect of 8-OH DPAT on hamster Per1 and Per2 mRNA levels in the SCN occurred only during the hamster's mid-subjective day, but not during the early subjective day or subjective night. The present findings demonstrate that the acute and circadian time-dependent reduction of Per1 and/or Per2 mRNA in the hamster SCN by 8-OH DPAT is strongly correlated with the phase resetting in response to 8-OH DPAT.

The mechanistic cause of the dramatic activity improvement of alumina-supported silver (Ag/Al 2 O 3 ) by H 2 addition for the selective catalytic reduction of NO with propane (C 3 H 8 -SCR) was investigated by catalytic and spectroscopic studies. In situ UV-vis, in situ EXAFS, IR, and microcalorimetric experiments show that H 2 reduction of Ag + ions on Ag/Al 2 O 3 at 573 K yields protons on alumina and partially reduced Ag n δ+ clusters, which are subsequently aggregated to larger Ag clusters. During H 2 + O 2 and H 2 -assisted C 3 H 8 -SCR reactions, Ag + ions and Ag n δ+ coexist. Reoxidation with O 2 results in the redispersion of the cluster to Ag + ion, accompanying a reaction of protons. The relationship between cluster size, redox properties, and catalytic activity is examined using Ag/Al 2 O 3 of different Ag loadings. The steady-state NO reduction rate correlates fairly well with the amount of Ag n δ+ during the H 2 -assisted C 3 H 8 -SCR reaction. It is shown that Ag n δ+ is the active species, whereas monomeric Ag + ion and metallic Ag particles are inactive. With Ag loading, the Ag + reduction rate increases and the rate of cluster reoxidation decreases. A balance between the rate of reduction and reoxidation of Ag species is an important factor that controls the size and oxidation state of the Ag species and consequently the catalytic activity of Ag/Al 2 O 3 . ESR has provided evidence, for the first time, for the in situ generation of superoxide ions in H 2 + O 2 and H 2 -assisted C 3 H 8 -SCR reactions. The comprehensive reason for the hydrogen effect in HC-SCR is discussed, focusing on the role of the cluster and protons on the reductive O 2 activation to superoxide ion.

The pathogenesis of severe acute respiratory syndrome (SARS) is poorly understood and cytokine dysregulation has been suggested as one relevant mechanism to be explored. We compared the cytokine profile in Caco2 cells after infection of SARS coronavirus (SARS-CoV) with other respiratory viruses including respiratory syncytial virus (RSV), influenza A virus (FluAV), and human parainfluenza virus type 2 (hPIV2). Interferon (IFN) system (production and response) was not suppressed by SARS-CoV infection. Therefore, SARS-CoV replication was suppressed by pretreatment with IFN. SARS-CoV and RSV induced high levels of IL-6 and RANTES compared with FluAV and hPIV2. Induction level of suppressor of cytokine signaling-3 (SOCS3) by SARS-CoV was significantly lower than that by RSV in spite of the significant production of IL-6. Toll-like receptors 4 and 9, which correlate with the induction of inflammatory response, were upregulated by SARS-CoV infection. Collectively, overinduction of inflammatory cytokine and dysregulation of cytokine signaling may contribute to the immunopathology associated with "severe" inflammation in SARS.

Dynamic structural changes of Ag in Ag-MFI upon H 2 reduction and subsequent reoxidation treatments were investigated by various characterization methods. Results of in situ time-resolved spectroscopies, UV-vis and quick XAFS, at 573 K show that Ag + ions at a cation-exchange site of preoxidized Ag-MFI are reduced by H 2 to a Ag 4 δ+ cluster. Protons on the zeolite (Brønsted acid sites) are also produced by the H 2 reduction of Ag-MFI as evidenced by IR measurements after D 2 adsorption. At higher reduction temperatures, the aggregation of Ag 4 δ+ clusters results in the formation of larger Ag n (n > 8) clusters, and Ag metal particles appear on the external surface of the zeolite. Upon reoxidation at 573 K, the silver clusters are redispersed to Ag + ions. The rate constant of cluster redispersion at 573 K depends on the oxidants used and increases in the order of NO(0.1%) + O 2 (10%) > O 2 (10%) > NO(0.1%). The activation energy for cluster formation in H 2 was lower than that for cluster redispersion during reoxidation with O 2 . The effect of Ag exchange level on the rate constants and apparent activation energies for Ag cluster formation in H 2 and Ag cluster redispersion in O 2 are also examined.

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It is known that Ca 21 -dependent phosphorylation of cAMP response element binding protein (CREB) and the rapid induction of mPer1 and mPer2, mouse period genes in the suprachiasmatic nucleus (SCN) are associated with lightinduced phase shifting. The CREB/CRE transcriptional pathway has been shown to be activated by calcium/calmodulin dependent kinase II (CaMKII) and mitogen-activated protein kinase (MAPK); however, there is a lack of evidence concerning whether the activation of CaMKII and/or MAPK elicited by photic stimuli are associated with the change in Per gene expression and behavioral phase shifting. In this experiment, we found there was an inhibitory effect by KN93, CaMKII inhibitor, on hamster Per1 and Per2 expression in the SCN and on phase delays in wheel running rhythm induced by light pulses. PD98059 and U0126, MAPK kinase inhibitors, however, affected neither light-induced Per1 and Per2 expression nor behavioral phase delays, even though PD98059 attenuated the light-induced phosphorylation of MAPK in the SCN. The present ®ndings demonstrate that the light-induced activation of CaMKII plays an important role in the induction of Per1 and Per2 mRNA in the hamster SCN as well as phase shifting. These results suggest that gated induction of Per1 and/or Per2 genes through CaMKII-CREB/ CRE accompanied with photic stimuli may be a critical step in phase shifting.

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Spontaneous dispersion and clustering processes of Pd were measured by means of the energy-dispersive EXAFS method. The spontaneous dispersion of bulky metal Pd into highly dispersed PdO was directly observed on the H-type zeolite in the atmosphere of O2. In contrast to H-type zeolites, simple oxidation of the agglomerated Pd was observed on Na-ZSM-5. The structural change of Pd was followed in the atmosphere of hydrogen. The clustering processes of metal Pd depended on the kind of zeolite, and these were categorized into three groups. The first group, i.e., Na-ZSM-5 and H-beta, showed monotonic agglomeration of metal Pd by increasing the reduction temperature. The second group consisted of H-ZSM-5 and H-mordenite where the formation of Pd6 clusters was found. On these zeolites, the generation of Pd6 clusters was reversibly observed upon the repetition of reduction and oxidation treatments. The third group consisted of H-Y and USY zeolites where the formation of Pd13 clusters was observed. From these findings, it was concluded that the crystal structure and acid sites of zeolites had profound influences on the dynamic behavior and the genesis of Pd clusters with various structures.