Functional coupling between sodium-activated potassium channels and voltage-dependent persistent sodium currents in cricket Kenyon cells.

In this study, we examined the functional coupling between Na(+)-activated potassium (KNa) channels and Na(+) influx through voltage-dependent Na(+) channels in Kenyon cells isolated from the mushroom body of the cricket Gryllus bimaculatus. Single-channel activity of KNa channels was recorded with the cell-attached patch configuration. The open probability (Po) of KNa channels increased with increasing Na(+) concentration in a bath solution, whereas it decreased by the substitution of Na(+) with an equimolar concentration of Li(+). The Po of KNa channels was also found to be reduced by bath application of a high concentration of TTX (1 µM) and riluzole (100 µM), which inhibits both fast (INaf) and persistent (INaP) Na(+) currents, whereas it was unaffected by a low concentration of TTX (10 nM), which selectively blocks INaf. Bath application of Cd(2+) at a low concentration (50 µM), as an inhibitor of INaP, also decreased the Po of KNa channels. Conversely, bath application of the inorganic Ca(2+)-channel blockers Co(2+) and Ni(2+) at high concentrations (500 µM) had little effect on the Po of KNa channels, although Cd(2+) (500 µM) reduced the Po of KNa channels. Perforated whole cell clamp analysis further indicated the presence of sustained outward currents for which amplitude was dependent on the amount of Na(+) influx. Taken together, these results indicate that KNa channels could be activated by Na(+) influx passing through voltage-dependent persistent Na(+) channels. The functional significance of this coupling mechanism was discussed in relation to the membrane excitability of Kenyon cells and its possible role in the formation of long-term memory.

Confomational analysis of soluble oligomers of GFP tagged prion protein by fluorescence fluctuation spectroscopy.

The conversion of prion protein (PrP) from the monomeric cellular isoform to the oligomeric pathological isoform is a crucial event in the pathogenesis of prion diseases. To investigate oligomer formation of PrP, enhanced green fluorescent protein (EGFP)-tagged PrP (EGFP-PrP) without the glycosylphosphatidylinositol (GPI) anchor was prepared and the oligomerization of EGFP-PrP induced by sodium dodecyl sulphate (SDS) was monitored by fluorescence correlation spectroscopy (FCS). The FCS analysis indicated that soluble oligomers were formed at 0.011% SDS. Furthermore, the combination of fluorescence cross-correlation spectroscopy (FCCS) and a panel of anti-PrP monoclonal antibodies (mAbs) revealed the conformational changes in PrP. Our studies provide a method to analyze conformational changes of proteins in solution.

Preliminary early intervention study using Nursing Child Assessment Teaching Scale in Japan.

BACKGROUND: Mother-infant interactions have been acknowledged as one of the most important elements in measuring outcomes of parent support and infant mental health interventions. The present study was conducted to measure early intervention outcomes using the Nursing Child Assessment Teaching Scale (NCATS), and to identify factors that affected Japanese mother-infant interactions. METHODS: Healthy Japanese mother-infant dyads who had lower scores on the NCATS, indicating potential problems, were assigned to an intervention group, and compared with a control group who had higher scores on NCATS. Health-care professionals visited the intervention group dyads in their homes, and gave them positive feedback on their interactions, consultations on parenting, and health advice. The control group dyads had home visitation once every 6 months for assessment only. RESULTS: The home visitations started at 3 months of age and continued until 18 months. NCATS scores in both groups were significantly different at baseline but differences faded by the end, which suggests that the intervention promoted improved interactions in the intervention group. Two of five factors were identified as influencing mother-infant interactions: maternal age; and personal networks, and together they significantly explained 27-30% of NCATS variance. CONCLUSION: The results appear to support the validity of measuring Japanese mother-infant interactions with NCATS. This study is the first to measure the outcomes of early intervention on Japanese dyads' interactions using NCATS. Additional replication studies should be conducted elsewhere in Japan, and clinical practices for promoting mother-infant interactions should begin to assess their effectiveness with NCATS as an outcome measure.