Systematic Study of Lattice Specific Heat of Filled Skutterudites

The lattice specific heat C lat of La-based filled skutterudites La T 4 X 12 ( T = Fe, Ru and Os; X = P, As, and Sb) has been systematically studied, and both the Debye temperature Θ D and the Einstein temperature Θ E of La T 4 X 12 were carefully estimated. We confirmed that a correlation exists between Θ D and the reciprocal of the square root of average atomic mass for La T 4 P 12 , La T 4 As 12 , and La T 4 Sb 12 . The Θ D of filled skutterudites was found to depend mainly on the nature of the species X forming the cage. The temperature dependence of C lat / T 3 for La T 4 X 12 exhibited a large broad maximum at low temperatures (10–30 K), which suggests a nearly dispersionless low-energy optical mode characterized by Einstein specific heat. Since no such broad maximum exists for the unfilled skutterudite RhP 3 , the low-energy optical modes are associated with vibration involving La ions in the X 12 cage (the so-called “guest ion modes”). The Θ E of filled skutterudites was found to roughly correspond to the energy of low-energy guest ion optical modes. Furthermore, a good correlation was shown to exist between Θ E and r R–X - r R3+ , where r R–X is the R – X distance and r R3+ is the effective ionic radius of R 3+ . As r R–X - r R3+ increased, Θ E was found to decrease

Thromboxane A2 mediates cation-induced airway hyperresponsiveness through the bradykinin B2 receptor in guinea pigs

To elucidate the mechanisms of cationic protein-induced airway hyperresponsiveness (AHR), the airway response to methacholine, and the concentrations of thromboxane B2 (TXB2) and 6-keto-PGF1α in the bronchoalveolar lavage fluid (BALF) of guinea-pigs were measured after inhalation of poly-L-lysine (P-L-L). The airway responsiveness (AR) was evaluated by specific airway resistance. The inhalation of P-L-L significantly enhanced AR to methacholine, and increased TXB2 and 6-keto-PGF1α in the BALF. The enhanced AR and the increase of TXB2 and 6-keto-PGF1α were both significantly inhibited by pretreatment with low molecular weight heparin (LMWH; anionic protein; 10 mg/mL for 6 min inhalation). Furthermore, thromboxane (TX) synthase inhibitor (ozagrel), thromboxane A2 (TXA2) receptor antagonist (ONO-3708), and bradykinin B2 receptor antagonist (BBRA; Nα-adamantaneacetyl-D-Arg [Hyp3, Thi5,8, D-Phe7]-bradykinin) inhibited the cation-induced AHR. BBRA significantly inhibited the increase of those mediators in the BALF. The data suggest that TXA2, which is newly generated by the stimulation of the bradykinin B2 receptor after inhalation of cationic proteins, plays an important role in cationic protein-induced AHR in guinea pigs

Effects of steroids on bone mineral content in women with bronchial asthma

The effects of corticosteroids on bone mass in patients with bronchial asthma (BA) are still controversial. To elucidate whether steroid administration may influence bone mineral content (BMC) and bone mineral density (BMD) in women with BA, a longitudinal study was designed for adult female asthmatics receiving long-term steroid therapy. We measured whole body BMC and lumbar BMD by dual energy X-ray absorptiometry in 23 women with BA and compared the results with those from 17 age-matched controls. Both patient and control groups were followed up for at least 1 year (mean (± SD) observation period 94 ± 33 weeks). We divided the asthmatic patients into two groups on the basis of the mode of steroid administration: (i) group A consisted of 10 patients with low dose oral steroid administration (prednisolone 5–10 mg daily); and (ii) group B consisted of 13 patients with low dose beclomethasone dipropionate (BDP) inhalation therapy (BDP 400–800 mg daily). There were no significant differences in both baseline values and changes of BMC and BMD among the three groups. These results demonstrate that asthmatic patients show normal bone mass and that both low dose steroid administration and BDP inhalation do not significantly affect BMC in patients with BA over the period studied. We suggest that appropriate steroid use does not augment bone mineral loss in asthmatics