Relationship between the body position-specific apnea-hypopnea index and subjective sleepiness.

BACKGROUND: It is well known that the sleeping position influences the rate of apnea-hypopnea events; however, whether events in one position may have more influence on daytime sleepiness than events in another position has not been thoroughly investigated. OBJECTIVES: We retrospectively examined the relationship between the body position-specific apnea-hypopnea index (AHI) and daily sleepiness. METHODS: We assessed the sleeping body position, the body position-specific AHI and the Epworth Sleepiness Scale (ESS) in a total of 699 patients who were referred for suspected obstructive sleep apnea-hypopnea syndrome (OSAHS) and underwent diagnostic polysomnography. RESULTS: For all subjects, only the lateral position-specific AHI (L-AHI) showed a weak but significant correlation with the ESS (r = 0.102; p < 0.05). For mild-to-moderate OSAHS patients, there was no correlation between the ESS and the AHI at any position. For severe OSAHS patients, the ESS showed a closer correlation with the L-AHI (r = 0.266; p < 0.001) than with the supine position-specific AHI (S-AHI; r = 0.141; p < 0.05). In a subgroup analysis, divided into positional and non-positional severe OSAHS patients, the correlation coefficients also identified a link between the L-AHI and the ESS. Finally, a multiple linear regression analysis indicated that the ESS was better explained by the L-AHI than by the S-AHI in severe OSAHS patients. CONCLUSION: The L-AHI is considered to have a stronger influence on daytime sleepiness than the S-AHI in Japanese patients with severe OSAHS.

Efficiencies of singlet oxygen production and rate constants for oxygen quenching in the S1 state of dicyanonaphthalenes and related compounds.

The quantum yield of singlet oxygen ((1)O(2) ((1)Delta(g))) production (Phi(Delta)) in the oxygen quenching of photoexcited states for 1,2-dicyanonaphthalene (1,2-DCNN), 1,4-dicyanonaphthalene (1,4-DCNN) and 2,3-dicyanonaphthalene (2,3-DCNN) in cyclohexane, benzene, and acetonitrile was measured using a time-resolved thermal lens (TRTL) technique, in order to determine the efficiency of singlet oxygen ((1)Delta(g)) production in the first excited singlet state (S(1)), (f(Delta)(S)). The efficiencies of singlet oxygen ((1)Delta(g)) production from the lowest triplet state (T(1)), (f(Delta)(T)), were nearly unity for all DCNNs in all the solvents. The values of f(Delta)(S) were fairly large for 1,2-DCNN (0.33-0.57) and 1,4-DCNN (0.33-0.66), but were close to zero for 2,3-DCNN. Rate constants for oxygen quenching in the S(1) state (k(q)(S)) obtained for these compounds were significantly smaller than diffusion-controlled rate constants. The kinetics for processes leading to production and no production of singlet oxygen is discussed on the basis of the values of f(Delta)(S) and k(q)(S). The results obtained regarding phenanthrene (PH), 9-cyanophenanthrene (9-CNPH), pyrene (PY) and 1-cyanopyrene (1-CNPY) are also discussed.

Solvent and pressure effects on quenching by oxygen of 9,10-dimethylanthracene fluorescence in liquid n-alkanes: a study on solvent cage effects.

The fluorescence quenching by oxygen of 9,10-dimethylanthracene (DMEA) in liquid ethane and propane at pressures up to 60 MPa and 25 degrees C was investigated. The apparent activation volumes for the quenching rate constant, k(q),DeltaV++(q) , were 5.0 +/- 3.4 and 7.4 +/- 1.0 cm(3)/mol, whereas those for the solvent viscosity, eta,DeltaV++(eta) , were 190 +/- 22 and 42 +/- 1 cm(3)/mol in ethane and propane at 6.0 MPa, respectively. These results were discussed together with those in n-alkanes (C(4)-C(7)) and methylcyclohexane (MCH) that were previously reported, and it was found that DeltaV++(q) increases monotonically but DeltaV++(eta) decreases rapidly with increasing the number of carbon atoms in n-alkanes. The plot of ln k(q) against ln eta showed a leveling-off with decreasing eta. These observations were analyzed satisfactorily by the pressure dependence of the solvent viscosity on k(q) coupled with that of the radial distribution function, g(sigma), at contact with a hard sphere assumption. The apparent bimolecular rate constant, k(bim,0), for the quenching in the solvent cage was evaluated by extrapolating to g(sigma)eta = 0 in the plot of g(sigma)/k(q) against g(sigma)eta, and it was found that k(bim,0) decreased with increasing the radius of the solvent molecule. From the solvent size dependence of k(bim,0), the solvent cage effect was discussed phenomenologically.