Thyroid hormone increases mRNA and protein expression of Na+-K+-ATPase alpha2 and beta1 subunits in human skeletal muscles.

CONTEXT: Thyroid hormone regulates specific Na+-K+-ATPase isoforms in rodent skeletal muscles. No study has examined this relationship in human tissues. OBJECTIVE: This study investigated the effect of hyperthyroid status on the expression of the alpha- and beta-subunits of the Na+-K+-ATPase. DESIGN: The vastus lateralis muscles from eight hyperthyroid patients were biopsied before and after treatment. Ten age-matched euthyroid subjects served as controls. RESULTS: In hyperthyroid patients, the average T3 level was three times higher in pretreatment compared with posttreatment (262 +/- 75 vs. 86 +/- 21 ng/dl, P = 0.001). The relative mRNA expression of the alpha2, but not alpha1 or alpha3, subunit was increased approximately 3-fold in pretreatment (2.98 +/- 0.52 vs. 0.95 +/- 0.40, P < 0.01), whereas that of beta1, not beta2 or beta3, subunit was increased approximately 2.8-fold in pretreatment (2.83 +/- 0.38 vs. 1.10 +/- 0.27, P < 0.01). The relative mRNA expression of the alpha2 and beta1 subunits was positively correlated with the serum T3 (r = 0.75, P = 0.001 and r = 0.66, P = 0.003, respectively). Immunohistochemistry studies revealed an increase in protein abundance of the alpha2 and beta1, but not alpha1 or beta2, subunits in the plasma membrane of muscle fibers of hyperthyroid patients, which decreased after treatment. CONCLUSIONS: This provides the first evidence that, in human skeletal muscles, thyroid hormone up-regulates the Na+-K+-ATPase protein expression at least, in part, at mRNA level, and the alpha2 and beta1 subunits play the important role in this regulation.

Epstein-Barr virus associated lymphoepithelial carcinoma of the parotid gland; a clinicopathological report of three cases.

Lymphoepithelial carcinoma is a relatively uncommon malignant tumor of the salivary gland demonstrating malignant epithelial cells with dense lymphoid stroma. The authors report three cases of lymphoepithelial carcinoma associated with Epstein-Barr virus of the right parotid gland with clinically presenting as painless, gradual enlargement of the preauricular mass. The histopathologic examination of the parotid gland is characterized by malignant epithelial cells with dense lymphoid stroma. Immunohistochemical stains show positive reactivity to cytokeratin and p53 in malignant epithelial cells. In situ hybridization of the Epstein-Barr virus-encoded Ribonucleic acid shows positivity in malignant epithelial cells. Clinical and pathologic features with relevant literatures are discussed. These are the first reported cases of primary parotid lymphoepithelial carcinoma associated with Epstein-Barr virus infection in Thailand and Southeast Asia.