Research on improved level set image segmentation method.

Aiming at the shortcomings of the traditional level set model which only has good robustness to the weak boundary and strong noise of the original target image, this paper proposes an improved algorithm based on the no-weight initialization level set model, introducing bilateral filters and using implicit surface level sets to extract and segment the original target image object more accurately, clearly and intuitively in the evolution process. The experimental simulation results show that, compared with the traditional non-reinitialized level set model segmentation method, the improved method can more accurately extract the edge contours of the target image object, and has better edge contour extraction effect, and the original target noise reduction effect of the improved model is better than that of the model before the improvement. The original target image object edge contour takes less time to extract than the conventional non-reinitialized level set model before the improvement.

Metabolites of arsenic and increased DNA damage of p53 gene in arsenic plant workers.

Recent studies have shown that monomethylarsonous acid is more cytotoxic and genotoxic than arsenate and arsenite, which may attribute to the increased levels of reactive oxygen species. In this study, we used hydride generation-atomic absorption spectrometry to determine three arsenic species in urine of workers who had been working in arsenic plants,and calculated primary and secondary methylation indexes. The damages of exon 5, 6, 8 of p53 gene were determined by the method developed by Sikorsky, et al. Results show that the concentrations of each urinary arsenic species,and damage indexes of exon 5 and 8 of p53 gene in the exposed population were significantly higher, but SMI was significantly lower than in the control group. The closely positive correlation between the damage index of exon 5 and PMI,MMA, DMA were found, but there was closely negative correlation between the damage index of exon 5 and SMI. Those findings suggested that DNA damage of exon 5 and 8 of p53 gene existed in the population occupationally exposed to arsenic. For exon 5, the important factors may include the model of arsenic metabolic transformation, the concentrations of MMA and DMA, and the MMA may be of great importance.

Increased damage of exon 5 of p53 gene in workers from an arsenic plant.

Mutagenesis is a multistage process. Substitution mutations can be induced by base modified through alteration of pairing property. Mutations of exon 5 and 8 of p53 gene have been found in most arsenicosis patients with precarcinomas and carcinomas, but never in arsenicosis individuals without precarcinomas and carcinomas. This study investigates whether base modification exists in exon 5 and 8 of p53 gene, and explores the dose-effect relationship between damage of exon 5 of p53 gene and urinary arsenic. Concentrations of urinary 8-hydroxydeoxyguanine (8-OHdG) are analyzed to identify the occurrence of DNA damage. The real-time PCR developed by Sikorsky et al. is applied to detect base modification in exon 5 and 8 of p53 gene for apparently healthy participants. Our results show that the mean total arsenic concentrations of two exposed groups from an arsenic plant are significantly elevated compared with the control group, and the damage level of exon 5 of the high-exposed group is significantly higher than that of the control group, but which does not happen in exon 8. The closely correlation between the damage index of exon 5 and urinary organic arsenic concentration are found. Concentration of 8-OHdG of the high-exposed group is significantly higher than that of the control group. These results imply that base modification in exon 5 of p53 gene can be induced by arsenic. In addition, our study suggests that the damage level of exon 5 is a useful biomarker to assess adverse health effect levels caused by chronic exposure to arsenic.

Methylation capacity of arsenic and skin lesions in smelter plant workers.

Potential occupational arsenic exposure is a significant problem in smelting plants. The metabolites containing arsenic with an oxidation of +3 have been considered more cytotoxic and genotoxic than their parent inorganic species. The current study examined the capacity of arsenic methylation and its risk on skin lesions. The primary aim of this study is to determine if methylation capacity, as measured by urinary arsenic metabolites, differed in workers with skin lesions compared to workers without skin lesions. Hydride generation-atomic absorption spectrometry was used to determine three arsenic species in urine of workers who had been working in arsenic plants, and primary and secondary methylation indexes were calculated. Skin lesions were examined at the same time. Many workers had obvious skin lesions (36/91). The mean concentrations of inorganic arsenic (iAs), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in urine of workers are obviously higher than those of the control group. There are more iAs, MMA, and DMA in urine, higher MMA%, lower iAs% for workers with skin lesions compared with those without skin lesions. Workers with skin lesions have the lowest SMI (3.50±1.21), and they may be in danger. Our results support the viewpoint that individuals who metabolize inorganic arsenic to MMA easily, but metabolize MMA to DMA difficulty have more risk of skin lesions.