Ameliorative effect of polydatin on oxidative stress‐mediated testicular damage by chronic arsenic exposure in rats

Arsenic causes lipid peroxidation leading to alterations in antioxidant status in organisms. In this study, the reproductive effects of chronic exposure to arsenic and the protective effects of polydatin (PD) were evaluated in 35 Wistar male rats, which were divided equally into five groups. The control group received a normal diet and tap water, arsenic (100 mg l^?1, approximately 1/50 of oral LD₅₀) was given via drinking water to experimental groups except control group, and PD was orally given to the other groups at dose of 50, 100 and 200 mg kg^?1 for 60 days. Arsenic administration decreased sperm motility, glutathione level, superoxide dismutase and catalase activities in testicular tissue of rats. In contrast, malondialdehyde level and DNA damage were found to be high levels in arsenic‐treated group. Histopathologically, it was observed that decreased sperm concentration and degeneration of Sertoli cells in testicular tissue. PD administration, partially 200 mg kg^?1, reversed arsenic‐induced lipid peroxidation, DNA damage, antioxidant enzyme activity and cell integrity in testis of rats. These results demonstrate that PD decreases arsenic‐induced lipid peroxidation, enhances the antioxidant defence mechanism and regenerates tissue damage in testis of rats.     

三氧化二砷联合化疗药物对神经母细胞瘤SK-N-SH细胞系杀伤作用的研究

目的观察三氧化二砷(As_2O_3)联合化疗药物对神经母细胞瘤SK-N-SH细胞系的毒性作用和细胞周期的影响,为临床寻找新的治疗手段和合理用药提供依据。方法采用流式细胞术检测单药,即As_2O_3、长春瑞滨、多西他赛、依托泊苷(VP16)或顺铂(DDP),或As_2O_3分别与另一种药物双药联合(同步给予As_2O_3和另一种药物;先予As_2O_3使SK-N-SH细胞周期阻滞在G2/M期后再予另一种药物)作用于SK-N-SH细胞24 h、48 h后不同处理组的凋亡率和细胞周期分布的差异。结果同步给药双药组的凋亡率均高于相应的单药组的凋亡率;As_2O_3与M期特异性化疗药物(长春瑞滨或多西他赛)联合用药时,非同步给药组即先予As_2O_3使SK-N-SH细胞周期阻滞在G2/M期后再加用长春瑞滨或多西他赛组的凋亡率高于相应单药组的凋亡率,As_2O_3与非M期特异性化疗药物(VP16或DDP)联合用药时,同步给药组即As_2O_3与VP16或DDP同步给药组的凋亡率高于相应单药组的凋亡率。联合用药组随着细胞凋亡率的变化,细胞周期的分布也发生了显著的变化,表现为随着SK-N-SH细胞凋亡率的增高,处于G2/M期的细胞比例减少。结论 As_2O_3与化疗药物联合用药或许能提高它们对SK-N-SH细胞的杀伤效果;当As_2O_3与M期特异性化疗药物(长春瑞滨或多西他赛)联合用药时,宜先采用As_2O_3的周期阻滞作用将NB细胞周期阻滞在G2/M期后再加M期特异性化疗药物的非同步给药方式;而当As_2O_3与非M期特异性化疗药物(VP16或DDP)联合用药时,宜采用同步给药的方式以提高杀伤效果。     

Portland cement修复磨牙髓室底穿孔的实验研究

目的 评估波特兰水门汀(Portland cement,PC)直接修复磨牙髓室底穿孔的效果,并与无机三氧化聚合物(mineral trioxide aggregate,MTA)作比较.方法 选取人新鲜拔除的恒磨牙53颗,按随机数字表法分为PC、MTA2个实验组(n=24)和1个对照组(n=5).实验组在髓室底中央制备直径2 mm的穿孔模型,分别用PC和MTA修复穿孔.对照组只开髓不制备穿孔模型.利用体视显微镜观察修复后样本的根分叉形态.扫描电子显微镜(SEM)观察材料和牙体组织的结合界面,并测量结合界面间隙宽度.采用葡萄糖定量法分析模型检测微渗漏值.结果 体视显微镜下两实验组对根分叉外形修复均达到了良好效果.SEM观察显示PC和MTA与牙体组织之间均可见不连续的微间隙存在,PC与牙体组织间隙宽度为(7.363±2.159) μm,MTA与牙体组织间隙宽度为(8.693±3.551) μm,两者无明显差异(P＞0.05).在观察期内,虽然PC组的微渗漏值小于MTA组,但无统计学差异(P＞0.05).结论 PC与MTA修复髓室底穿孔的封闭效果相当,且PC价格低廉,不易使牙体变色,可以考虑作为MTA替代材料进一步研究.     

Short communication phosphate supply and arsenate toxicity in ectomycorrhizal fungi

Three species of ectomycorrhizal fungi (Hebeloma crustuliniforme, Suillus variegatus and Cenococcum geophilum) were grown in axenic culture amended with range of AsO4(3-) concentration under three different PO4(3-) regimes. The fungi exhibited different growth responses to AsO4(3-) that varied with PO4(3-) concentration. Suillus variegatus showed the greatest sensitivity to AsO4(3-), with growth almost completely inhibited in the presence of AsO4(3-) under the lower two PO4(3-) treatments. Under the highest PO4(3-) treatment however, growth was enhanced and S. variegatus was able to persist at AsO4(3-) concentrations of up to 4 mM. Hebeloma crustuliniforme also showed high sensitivity to AsO4(3-) especially at low PO4(3-) concentration. The two higher PO4(3-) treatments had an ameliorating effect on AsO4(3-) toxicity in H. crustuliniforme. This demonstrates the ability of PO4(3-) to alleviate AsO4(3-) toxicity. The response from S. variegatus and H. crustuliniforme, both basidiomycetes, was in contrast to the ascomycete C. geophilum. This fungus demonstrated tolerance to AsO4(3-) when grown in culture solution and PO4(3-) did not have an ameliorating effect on AsO4(3-) toxicity in C. geophilum.     

Alteration of thiol-disulfide homeostasis in workers occupationally exposed to arsenic

This study evaluates the redox state in occupationally arsenic-exposed workers (n = 71) by assessing the dynamic serum thiol-disulfide homeostasis. We determined the serum thiol-disulfide homeostasis parameters of exposed workers and controls (n = 43) using a novel automated colorimetric assay. Median urinary As and 8-isoprostane levels of exposed group were significantly higher than control group (16.40 μg/L vs 2μg/L, p < .001 and 2.28 ng/ml vs 0.54 ng/ml, p < .001, respectively). Disulfide level, disulfide/native thiol ratio, and disulfide/total thiol ratio were significantly higher in exposed group. The mean ceruloplasmine and myeloperoxidase activities of As-exposed group were significantly higher than control group (117.15 U/L vs 87.02 U/L, p = .035 and 148.53 U/L vs 97.75 U/L, p = .000, respectively). The median catalase activity did not differ in the two groups. Our findings revealed that As disrupts the thiol-disulfide homeostasis in favor of disulfide.     

The hypothetical roles of arsenic in multiple sclerosis by induction of inflammation and aggregation of tau protein: A commentary

Multiple sclerosis (MS) is a disease which manifests demyelination of neuronal cells in the brain. Despite extensive research on the mechanisms of disease development and progression, the exact mechanism is not elucidated yet, which has hampered drug development and subsequent treatment of the disease. We have recently shown that the serum levels of arsenic and malondialdehyde, a lipid peroxidation marker, are high in MS patients. In this article, we would like to formulate the hypothesis that arsenic may cause MS by induction of inflammation, degeneration, and apoptosis in neuronal cells. The induction of ROS generation in cells upon exposure to arsenic as a heavy metal may be involved in the pathogenesis of MS. Tau protein, a member of the family of microtubule-associated proteins, is mainly expressed in neurons and contribute to the assembly of neuronal microtubules network. Arsenic may affect the hyperphosphorylation and aggregation of tau proteins and may be involved in the cascade leading to deregulation of tau function associated with neurodegeneration. For validation of this hypothesis, studies might be conducted to evaluate the association of arsenic levels and tau protein levels in MS patients. Further studies might also focus on the trafficking along microtubules in neurons of MS patient with regard to hyperphosphorylation of tau protein. This hypothesis may add a new dimension to the understanding of MS etiology and help to design novel therapeutic agents against potential targets that might be discovered. If this hypothesis proves to be true, tau phosphorylation inhibitors can be potential candidates for MS drug development.     

Contemporary management of lateral root perforation diagnosed with the aid of dental computed tomography

Lateral root perforation unnoticed during post-space preparation, and followed by post cementation, can subsequently be challenging to diagnose in the labio-lingual plane due to the two-dimensional nature of conventional radiography. This paper demonstrates the application of a recently developed three-dimensional imaging system, cone beam computed tomography, in the diagnosis of iatrogenic root perforation. A clinical case is reported where labial post perforation in a maxillary central incisor occurring 15 years previously presented with a sinus tract and radiolucent lesion. Non-surgical retreatment and perforation repair using mineral trioxide aggregate was performed with the aid of an operating microscope. The sinus tract resolved with radiographic evidence of healing at 1-year recall.