Acute and subchronic toxicity studies of rhein in immature and d-galactose-induced aged mice and its potential hepatotoxicity mechanisms.

Rhein is a key ingredient in many herbal remedies and is widely used. However, herbs containing rhein are frequently associated with poisoning incidents, especially in elderly subjects. Acute and subchronic toxicity of rhein in Kunming mice (KM) was investigated in this experiment. Acute toxicity tests showed a 40% lethality at a given rhein dose of 4000 mg/kg, and the LD50 of rhein was calculated by the bliss method to be greater than 2185.6 mg/kg. In subchronic toxicity, d-gal-induced aged and immature animals were randomized into three groups that were exposed to rhein of 0, 175, and 375 mg/kg/d for 75 days, respectively. No mortality was observed in immature mice group, whereas 55.5% (5/9) subjects in aged mice groups died in the high dosage group. AST, ALT, IL-6, TNF-α levels and typical histopathological changes indicate that rhein causes liver injury. In addition, our investigation explored possible hepatotoxic mechanisms of rhein and experimental results showed increased ROS production, NRF-2 and MDA levels and decreased SOD levels, demonstrating that rhein causes oxidative stress. MMP and mitochondrial swelling levels were able to assess the impact of rhein on mitochondrial function. Furthermore, the effect of rhein on apoptosis can be detected by flow cytometry. Our studies suggested that rhein induces oxidative stress leading to mitochondria dysfunction and apoptotic activation. Multidrug resistance protein (MRP) is an efflux transporter protein and is capable of transporting cellular oxidative stress-related substances. To further clarify the role of MRP in rhein induced oxidative stress, we examined MRP expression in the liver. However, the expression of MRP has no statistical significance.

Studies on the genus Psephenothrips Reyes from China (Thysanoptera, Phlaeothripinae), with one new species.

Species from China of the Asian genus Psephenothrips are reviewed, with P. eriobotryae sp. nov. collected from the leaves of Eriobotrya japonica in Sichuan Province. A key to the five species known from China is provided and the COI sequence of the new species is also given.

A study on acquired acid resistance of enamel and dentine irradiated by Er, Cr: YSGG laser in vitro / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the acid resistance of enamel and dentin irradiated by Er, Cr: YSGG laser to artificial caries formation in vitro.</p><p><b>METHODS</b>Enamel and dentin samples were irradiated with Er, Cr: YSGG laser at 6 W or 4 W for 6 second, respectively. Every sample was immersed in 3 ml of lactic demineralization solution at pH 4.8 and incubated at 37 degrees C for 24 hours. The parts per million of calcium ion of each solution was measured by atomic absorption spectrophotometry, the quantities of calcium and phosphate on the surface of enamel and dentin sample were examined by SED-X and the ultrastructure was investigated by SEM.</p><p><b>RESULTS</b>In the enamel and dentin samples, the dissolved Ca(2+) concentration in laser group were significantly decreased compared with that of the control group (P < 0.05). The quantities of Ca (weight%) in enamel and dentin were significantly higher in the laser group than in the control group (P < 0.05). The content of P was increased in dentin and enamel samples, but only the increase in enamel sample was significant (P < 0.05). In both samples, no significant changes on Ca/P weight ratio were found between the groups. The irradiated enamel and dentin surface lacked a smear layer and showed various patterns of microirregulation with a scaly appearance, the openings of dentinal tubules were clearly visible, but no melting or carbonization was observed.</p><p><b>CONCLUSION</b>Er, Cr: YSGG laser irradiation is effective for increasing acid resistance of dental hard tissue and does not cause thermal side effect.</p>