RESUMEN
After spiking anoxic sediment slurries of three acidic oligotrophic lakes with either HgCl(2) at 1.0 mug/ml or CH(3)HgI at 0.1 mug/ml, both mercury methylation and demethylation rates were measured. High mercury methylation potentials were accompanied by high demethylation potentials in the same sediment. These high potentials correlated positively with the concentrations of organic matter and dissolved sulfate in the sediment and with mercury levels in fish. Adjustment of the acidic sediment pH to neutrality failed to influence either the methylation or the demethylation rate of mercury. The opposing methylation and demethylation processes converged to establish similar Hg-CH(3)Hg equilibria in all three sediments. Because of their metabolic dominance in anoxic sediments, mercury methylation and demethylation in pure cultures of sulfidogenic, methanogenic, and acetogenic bacteria were also measured. Sulfidogens both methylated and demethylated mercury, but the methanogen tested only catalyzed demethylation and the acetogen neither methylated nor demethylated mercury.
RESUMEN
Yonsei Cancer Center developed an RF(Radiofrequency) capacitive type heating device, GHT-RF8(Greenytherm) in cooperation with Green Cross Medical Corp., Korea in 1986 for the first time in Korea. Cooperative clinical studies of hyperthermia for the treatment of cancer using GHT-RF8 were conducted by Yonsei Cancer Center in collaboration with the Presbyterian Medical Center, Chonju, Korea. A total of forty patients with various histologically proven malignant tumors, including superficial (N = 13) and deep-seated tumors (N = 27), were treated with this newly developed heating device in conjunction with radiotherapy (N = 38) or chemotherapy (N = 2) at two different institutes between October 1986 and September 1987. These patients were locally far advanced or recurrent cases and considered to be refractory to conventional cancer treatment modalities. Radiotherapy was given in 200cGy per day, five times a week fractionations with a total tumor dose of 50-60Gy in 5-6 weeks. Within an hour after radiotherapy, the RF capacitive type of hyperthermia was given two times a week for a total of 4-10 treatment sessions and an attempt was made to maintain the tumor temperature at 41-45 degrees C for 30-60 minutes. Of forty patients treated, 14 patients with deep-seated tumors showed complete response and 20 patients showed partial response. The overall response rate was 85% (34 out of 40 patients) and only 6 patients showed no response. Complications from this treatment were mainly burns, superficial first degree burn in 2 cases, second degree in 4 cases and subcutaneous fat necrosis was observed in 2 cases.(ABSTRACT TRUNCATED AT 250 WORDS)