Steroid myopathy: pathogenesis and effects of growth hormone and insulin-like growth factor-I administration.

Glucocorticoids have been widely used in the treatment of autoimmune and other diseases. Chronic steroid use, however, could cause proximal muscle weakness and atrophy, termed steroid myopathy. The onset of steroid myopathy is usually insidious and there are no specific laboratory findings except for elevated urinary creatine excretion. Muscle biopsy reveals non-specific type II fiber atrophy. There are many reports showing preventive effects of either growth hormone (GH) or insulin-like growth factor (IGF)-I on steroid myopathy. The pathogenesis of steroid myopathy is not fully understood. Recently, glutamine synthetase has been reported to play a key role in steroid myopathy. GH as well as IGF-I decreased the steroid-induced glutamine synthetase activity in skeletal muscle.

Kinetic and thermodynamic analysis of the cyclodextrin-allyl isothiocyanate inclusion complex in an aqueous solution.

The decomposition of allyl isothiocyanate (AITC) in an aqueous solution was depressed in the presence of cyclodextrin (CD), it's suppression effect increasing in the order of none < beta-CD < alpha-CD. The results of kinetic and thermodynamic analysis of the CD-AITC inclusion complexes showed that the inclusion process was mostly governed by an enthalpy change (delta H degree) rather than by an entrophy change (delta S degree), and that Van der Waals forces played a primary role int he inclusion. Steric factors were important for the reaction activity of AITC inclusion into the CD cavity, especially significant being the stereospecificity between the size of the CD cavity and the AITC molecule which is the main factor concerning it's activity. Our results suggest that the association stability and activity of the included AITC molecule are important factors in the suppression mechanism for CDs. Therefore, both these factors would make an alpha-CD-AITC system more advantageous than a beta-CD-AITC system, and the marked suppression effect of alpha-CD on the decomposition of AITC can be attributed to the formation of inclusion complexes in an aqueous solution.

Preventive effects of insulinlike growth factor-I on steroid-induced muscle atrophy.

We examined the effects of simultaneous administration of recombinant insulinlike growth factor-I (IGF-I) and glucocorticoid on the diameter of muscle fibers in rats. The steroid group received subcutaneous injection of triamcinolone, the IGF-treated group received IGF-I alone, and the steroid plus IGF group received both triamcinolone and IGF-I. After 14 days, each rat was subjected to muscle biopsy of the extensor digitorum longus and soleus. Glucocorticoid treatment caused significant reduction in diameter of muscle fibers, compared to controls. Simultaneous administration of IGF-I significantly attenuated glucocorticoid-induced muscle atrophy. Glucocorticoid increased both urinary concentration of 3-methylhistidine and urinary creatine/creatinine ratio. IGF-I reduced those changes in the urine. We conclude that IGF-I administration prevents, at least partially, the development of steroid myopathy.

Theoretical and experimental investigations of loss behavior in the infrared in quartz hollow waveguides with rough inner surfaces.

Transmission losses in quartz hollow waveguides with rough inner surfaces have been measured, and an anomalous loss decrease has been observed just beyond the resonance wavelength at the infrared. Detailed analyses have been conducted to check the applicability of available theories in the prediction of additional loss increases or decreases in wide infrared-wavelength regions. A new theory based on a thin-film-coating model has also been presented for the first time, to our knowledge, to describe the additional loss behavior.