Metallothionein(MT) is a low molecular weight protein that is induced as a defence mechanism for cadmium (Cd) toxicity. In present study, urinary MT was determined using a competitive ELISA in Cd-exposed rats. In addition, measures the urinary, blood and renal Cd concentration and the urinary excretion of total protein, beta 2-microglobulin (MG) and N-acetyl-beta-D-glucosaminidase(NAG) at 1, 3, 7, 14, 28 days after Cd injection in Cd-exposed rats with dosers of 0.8 and 1.6 mg Cd/kg body weight respectively. The urinary, blood and renal Cd were specific for Cd-exposure, that increased in proportional to dose of Cd. The urinary and blood Cd tended to slightly decrease, while renal Cd tended to increase by lapse of time after Cd exposure. this finding indicates that renal Cd is more specific than urinary and blood Cd for Cd exposure. The urinary excretion of MT showed a statistically significant increase in Cd exposed rats(0.8 and 1.6 no Cd/kg body weight). The increase of urinary excretion of MT was more evident at 7, 14, 28 lays after Cd exposure than the changes of urinary excretion of total protein, beta-MG and NAG. The Pearson's correlation coefficients between urinary Cd and urinary MT, beta-MG, NAG and total protein were 0.4344, 0.3727, 0.3307 and 0.2099, respectively. These findings indicate that the urinary MT is more sensitive and specific than total protein, beta-MG and NAG for Cd exposure. The present results suggest that the urinary MT, using a simple and rapid competitive ELISA, is a valuable index as screening test in epidemiologic study for Cd exposed group.
Metallothionein (MT) is a cadmium binding protein that played major' roles in protective mechanism for cadmium toxicity. In the present study, competitive ELISA was established to assay the MT expression utilizing monospecific antibody which was generated against MT-L A total of 10 Sprague-Dawley rats was injected with CdCl2 for two weeks to induce MT. The cytosolic fraction of rat liver was obtained by differential centrifugation. Two major MT isozymes (MT-I & MT-II) at ca. 10 kDa were purified by Sephadex G-75 gel filtration followed by DEAE-Trisacryl-M anion exchange column chromatogra-phy, respectively. Two rabbits were immunized 4 times consecutively with the conjugate of purified MT-L The sera were collected by heart puncture. When immunoblot was carried out, the immunized rabbit sera (anti-MT-I) exhibited specific immunoreactive band at MT-I while showed any cross reactions neither with MT-II nor with other cytosolic proteins.. By chequerboard titration using the monospecific antibody, the competitive ELISA was established. The dose-dependent relationship was observed between anti-MT-I antibody and the amount of MT in biological samples (r(2)=O.9980). These results suggested strongly that competitive ELISA is a simple, rapid and reproducible method for screening cadmium exposure.
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Evaluation of factors associated with cadmium exposure and kidney function in the general population Mingai Huang, Seong‐Jin Choi, Dong‐Won Kim, Na‐Young Kim, Hye‐Sun Bae, Seung‐Do Yu, Dae‐Seon Kim, Heon Kim, Byung‐Sun Choi, Il‐Je Yu, Jung‐Duck Park Environmental Toxicology.2013; 28(10): 563. CrossRef
This study was conducted to investigate the metallothionein induction by sodium selenite in mercuric Chloride intoxication. Mercuric chloride of 3.0 mg/kg of body weight was administered simultaneously with sodium selenite of either a high dosage of 2.5 mg/kg or low dosage of 1mg/kg via intraperitioneal injecion to rats. After the treatment, 6, 12, 24 and 72 hours later, mercury and selenium content in liver and kidney tissues, serum transaminase activities(SGOT, SGPT), metallothionein, glutathione, glutathione peroxidase sotivity and histological changes were determined.
The results were summarized as follows on: 1. The combined administration of mercury and selenium significantly more decreased mercury concentrations in liver and kidney compared to the administration of mercury only.
2. The combined administration of mercury and selenium significantly more increased renal metallothionein compared to administration of mercury only. This phenomenon was more remarkable when a large dose(2.5 mg/kg) of selenium was administered with mercuric chloride.
3. Glutathione concentration, glutathione peroxidase activity in liver and kidney and serum transaininase activity(SGOT, SGPT) were less suppressed in the combined administration group than the mercury only group.
4. Histological damage in renal tissue was not revealed in rats treated with mercury and selenium.
From the above results, selenium administered simultaneously with mercury decreased mercury concentration in liver and kidney, increased renal metallothionein concentration and decreased the toxicity of mercury. The hypothetic mechanism suggested is that selenium induces the metallothionein combined with Hg and redistributes Hg in tissues.
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