Mutual detoxification of mercury and selenium in unicellular Tetrahymena.

Selenium (Se) is commonly recognized as a protective element with an antagonistic effect against mercury (Hg) toxicity. However, the mechanisms of this Hg-Se antagonism are complex and remain controversial. To gain insight into the Hg-Se antagonism, a type of unicellular eukaryotic protozoa (Tetrahymena malaccensis, T. malaccensis) was selected and individually or jointly exposed to two Hg and three Se species. We found that Se species showed different toxic effects on the proliferation of T. malaccensis with the toxicity following the order: selenite (Se(IV))>selenomethionine (SeMeth)>selenate (Se(VI)). The Hg-Se antagonism in Tetrahymena was observed because the joint toxicity significantly decreased under co-exposure to highly toxic dosages of Hg and Se versus individual toxicity. Unlike Se(IV) and Se(VI), non-toxic dosage of SeMeth significantly decreased the Hg toxicity, revealing the influence of the Se species and dosages on the Hg-Se antagonism. Unexpectedly, inorganic divalent Hg (Hg2+) and monomethylmercury (MeHg) also displayed detoxification towards extremely highly toxic dosages of Se, although their detoxifying efficiency was discrepant. These results suggested mutual Hg-Se detoxification in T. malaccensis, which was highly dependent on the dosages and species of both elements. As compared to other species, SeMeth and MeHg promoted the Hg-Se joint effects to a higher degree. Additionally, the Hg contents decreased for all the Hg-Se co-exposed groups, revealing a sequestering effect of Se towards Hg in T. malaccensis.

Interaction of methylmercury and selenium on the bioaccumulation and histopathology in medaka (Oryzias latipes).

Interaction of methylmercury and selenium in medaka (Oryzias latipes) on bioaccumulation of pollutants and histopathological changes in liver and gill were studied. Juvenile medaka fish were submitted to a series of waterborne methylmercury chloride (MMC), sodium selenite (Na(2)SeO(3)) and their mixture for 210 days, respectively. The methylmercury (MeHg) and selenium contents in the whole body of medaka were determined. The dose- and time-dependent increase of MeHg and selenium contents in medaka were observed. Histopathological changes, such as edema, vacuoles, pyknotic nucleus, and telangiectasis, could clearly be observed in the slices from the exposed medaka's liver and gill. Concurrent exposure to MMC and Na(2)SeO(3) showed the increased selenium accumulation. When the exposure molar ratio of MeHg:Se was about 1, the interaction between MeHg and selenium offered a limited protection against the serious intoxication of both MMC and Na(2)SeO(3) to medaka.

[Effects of irrigating solution of Sihuang on morphology and function of nasal mucosa following surgery for chronic sinusitis and nasal polyps].

OBJECTIVE: To investigate the effect of the irrigating solution of Sihuang (ISSH) given after endoscopic surgery for chronic sinusitis and nasal polyps. METHODS: ISSH was used to irrigate the operated sinus cavity for 4 weeks in 109 patients with chronic sinusitis and/or polyps treated by endoscopic surgery, and 0.9%; normal saline (NS) was given in the same manner in another 109 patients receiving ISSH for similar problems, and the effects of the irrigating solutions was compared. Before and 3 months after the surgery, respectively, 32 patients with sinusitis were selected from each group for saccharin test. The mucosa in the ostiomeatal complex region was examined by electron microscopy in 6 patients before, two weeks and one month after surgery, respectively. RESULTS: The total effective rate was not significantly different between the two groups, but the postoperative morphological and functional recovery of the nasal mucosa occurred earlier in ISSH than in NS group (P<0.05). The level of SIgA was similar between the two groups before treatment (P>0.05), whereas after ISSH treatment, the SIgA level was significantly elevated in the treated group. Mucociliary transport rate was similar between ISSH and NS groups before the surgery (3.14+/-1.05 mm/min vs 3.31+/-1.09 mm/min, P>0.05), but 3 month after the surgery, the mucociliary transport rate increased to 6.09+/-2.63 mm/min in ISSH group and 5.04+/-1.22 mm/min in NS group, showing significant difference between them. Under electron microscope, the cilia of the epithelial cells were found exfoliated preoperatively but regularly arranged after the surgery, presenting the "9+2" architecture of the microtubule. CONCLUSION: ISSH used after operation can improve the therapeutic effect of endoscopic surgery for chronic sinusitis and/or nasal polyps.