THST appears more likely than placebo or no treatment to significantly reduce benign thyroid nodule volume, but long-term treatment may be less effective and regrowth is likely following cessation of therapy. Given the risks of THST, routine use is not recommended for benign nodules.

Encephaloceles of the temporal bone are encountered rarely in otologic medicine. Given the possibility of cerebrospinal fluid leaks and meningitis, however, the otolaryngologist or otologist must have a working knowledge of the correct diagnostics and treatments.

The ␣-dystroglycan binding properties of laminins extracted from fully differentiated skeletal muscle were characterized. We observed that the laminins expressed predominantly in normal adult rat or mouse skeletal muscle bound ␣-dystroglycan in a Ca 2؉ -dependent, ionic strength-sensitive, but heparin-insensitive manner as we had observed previously with purified placental merosin (Pall, E. A., Bolton, K. M., and Ervasti, J. M. 1996 J. Biol. Chem. 271, 3817-3821). Rat skeletal muscle laminins partially purified by heparin-agarose affinity chromatography also bound ␣-dystroglycan without sensitivity to heparin. We also confirm previous studies of dystrophic dy/dy mouse skeletal muscle showing that the ␣2 chain of merosin is reduced markedly and that the laminin ␣1 chain is not up-regulated detectably. However, we further observed a quantitative decrease in the expression of laminin ␤/␥ chain immunoreactivity in ␣2 chain-deficient dy/dy skeletal muscle and reduced ␣-dystroglycan binding activity in laminin extracts from dy/dy muscle. Most interestingly, the ␣-dystroglycan binding activity of residual laminins expressed in merosin-deficient dy/dy skeletal muscle was inhibited dramatically (69 ؎ 19%) by heparin. These results identify a potentially important biochemical difference between the laminins expressed in normal and dy/dy skeletal muscle which may provide a molecular basis for the inability of other laminin variants to compensate fully for the deficiency of merosin in some forms of muscular dystrophy.

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