Effect of cisplatin on the expression of glutathione-S-transferase in the cochlea of the rat.

Glutathione-S-transferase (GST) has been found to conjugate glutathione (GSH) to diverse electrophiles and play a major role in the detoxification of alkylating and platinating agents. However, there is little information regarding the pattern of GST expression in the cochlea. Although cisplatin is ototoxic, its effect on GST in the cochlea is unknown. In the present study we investigated the pattern of GST expression in control and cisplatin-treated cochleas by using the laboratory rat as animal model. Sixteen mature rats were randomly assigned to control or cisplatin groups. After treatment, cochleas were procured and tissues stained by immunohistochemical methods to detect the presence of GST. Optical density measurements were determined to gauge intensity of GST immunostaining. Strong positive GST immunostaining was demonstrated in all cochleas, with the most intense staining found in the spiral ligament and the least in Reissner's membrane. Mean optic density scores were lower for cisplatin-treated cochleas than for control cochleas in all areas analyzed. These findings showed that GST is expressed throughout the rat cochlea, with cisplatin treatment causing its decreased expression.

Hypoparathyroidism counteracts risk factors for osteoporosis.

Although increased bone density has been reported in patients with hypoparathyroidism, it is not known whether hypoparathyroidism can overcome the influence of risk factors for osteoporosis and whether the increased bone density is uniform throughout the entire skeleton or greater in certain regions depending on the bone composition and location. In the current study, bone density was measured in patients with postsurgical hypoparathyroidism and risk factors for osteoporosis. Bone mineral density was determined in eight patients with postsurgical hypoparathyroidism, one with idiopathic hypoparathyroidism, and two with pseudohypoparathyroidism in eight different areas of the skeleton using well established methods: single photon absorptiometry of the radius, dual energy x-ray absorptiometry of the spine, hip, and the whole skeleton, and quantitative computed tomography of the spine. Risk factors for osteoporosis were documented in each subject. The data showed that despite the presence of 1-4 risk factors for osteoporosis, patients with postsurgical hypoparathyroidism had bone mineral density above the normal mean in most locations. The locations with the highest increment were the Ward's triangle and the trochanter area of the proximal femur (dual energy x-ray absorptiometry) (Ward's: Z score + 1.59 +/- 0.57, P < 0.03; trochanter 1.31 +/- 0.42, P < 0.02). The elevation of bone density was not observed in one patient with idiopathic hypoparathyroidism, and variable results were observed in two patients with pseudohypoparathyroidism. Based on these findings, in postsurgical hypoparathyroidism, the bone mineral density is above the normal mean despite the presence of risk factors for osteoporosis, and both cortical and trabecular bone are affected.