[The study on biological exposure index of occupational exposure to arsenic and its inorganic compounds].

Objective: To establish biological exposure index (BEI) of occupational exposure to arsenic and its inorganic compounds through occupational epidemiology and the regression analysis of internal and external exposure of workers. Methods: In November 2021, 125 workers with occupational exposure to arsenic and its inorganic compounds and 49 office administrators in a non-ferrous metal smelter in Yunnan Province were selected as the exposure group and control group, respectively. Air samples from the workplace of the study subjects on weekdays were collected and arsenic concentrations were determined. Urine samples were collected in end-of-work weekend and high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used to detect the levels of trivalent inorganic arsenic (iAs(3+)) , pentavalent inorganic arsenic (iAs(5+)) , monomethyl arsenic (MMA) and dimethyl arsenic (DMA) in urine. The correlations between arsenic concentration in the workplace air and arsenic species in urine of workers were analyzed. Arsenic exposure concentration and the level of urinary arsenic (ΣiAs+MMA+DMA) of workers was analyzed by linear regression and the BEI of arsenic and its inorganic compounds in the workplace was proposed based on the results of micronucleus test. Results: The median of time-weighted average concentration (C(TWA)) of arsenic in the workplace air of the exposure group was 0.0116 mg/m(3), and the over-standard rate was 71.2% (89/125) . The concentrations of iAs(3+), iAs(5+), inorganic arsenic (iAs=ΣiAs(3+)+iAs(5+)) 、MMA、DMA and urinary arsenic in the exposure group were higher than those in the control group at the end of shift, and the differences were statistically significant (P<0.05) . The concentration of arsenic in the workplace air had the strongest correlation with the concentration of urinary arsenic at the end of the shift (r(s)=0.909, P<0.001) . The regression equation was lg (y) =7.662+2.968lg (x) (r=0.821, P<0.05) . According to the occupational exposure limit (OEL) of arsenic in China, the concentration of urinary arsenic in the end-of-work weekend was calculated to be 53.2 µg/L. Combined with the results of micronucleus test, the BEI of occupational exposure to arsenic and its inorganic compounds in the workplace was proposed to be 50 µg/L. Conclusion: The urinary arsenic in the end-of-work weekend can be used as a biomarker of occupational exposure to arsenic, and its BEI is recommended to be 50 µg/L.

[Correlation analysis of urinary arsenic species and health effect indicators of occupational arsenic exposure workers].

Objective: To explore the correlation between urinary arsenic and health effects through the determination and analysis of urinary arsenic levels in occupational arsenic exposed workers. Methods: In November 2021, 95 workers exposed to arsenic and its inorganic compounds and 31 administrative personnel from a non-ferrous metal smelter in Yunnan Province were selected as the contact group and control group, respectively. Urine forms of arsenic, blood tumor markers, liver function were detected, and micronucleus test was used to analyze the chromosome damage. The correlation between urine forms of arsenic and health effects were analyzed. Results: Compared with the control group, the concentrations of urinary trivalent inorganic arsenic (iAs(3+)) , pentavalent inorganic arsenic (iAs(5+)) , inorganic arsenic (iAs=ΣiAs(3+)+iAs(5+)) , monomethyl arsenic (MMA) , dimethyl arsenic (DMA) and urinary arsenic (ΣiAs+MMA+DMA) at the end of class in contact group were higher (P<0.05) . There was no statistically significant difference in blood tumor markers and liver function indicators between the two groups (P>0.05) . Compared with the control group, the peripheral blood micronucleus rate and cell micronucleus rate in the contact group were significantly increased (P<0.05) . The urinary arsenic, iAs(5+), inorganic arsenic and DMA were positively correlated with peripheral blood micronucleus rate in contact group (r(s)=0.48, 0.34, 0.37, 0.23, P<0.05) , and the urinary arsenic, iAs(5+), DMA were positively correlated with peripheral blood micronucleus rate (r(s)=0.48, 0.34, 0.26, P<0.05) . Conclusion: There is a significant correlation between different valence states of arsenic in the urine and abnormal health effects of occupational arsenic exposed workers. It is necessary to strengthen the detection of arsenic species in the urine of occupational arsenic exposed workers to better protect their health.

[The role of renal tubular epithelial cells in cadmium-induced renal fibrosis].

Objective: To investigate the role of renal tubular epithelial cells in cadmium-induced renal fibrosis. Methods: Established a sub-chronic cadmium exposure mouse model and analyzed the progress of renal fibrosis induced by cadmium exposure through Masson staining and immunohistochemistry, and then a co-culture system of renal tubular epithelial cells and renal fibroblasts was established, the levels of proliferation and activation of renal fibroblasts were detected by Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and Western blotting. Results: Sub-chronic cadmium exposure led to weight loss in mice (P<0.05) , and the levels of ß-microglobulin (ß-MG) and N-acetyl ß-D-glucosaminidase (NAG) in urine were increased in mice exposed to cadmium (P<0.05) ; pathological analysis revealed that sub-chronic cadmium exposure damaged renal tubular structure, causing infiltration of inflammatory cells and deposition of collagen fiber by Masson (P<0.05) , which in turn induced kidney fibrosis in mice; the results of in vitro co-culture experiments showed that cadmium-exposed renal tubular epithelial cells accelerated the synthesis of collagen in renal fibroblasts and promoted the proliferation and activation of renal fibroblasts (P<0.05) . Conclusion: In the progression of cadmium-induced renal fibrosis, a deleterious renal epithelial-fibroblast cross talk was formed, which may be one of the important mechanisms of cadmium-induced renal fibrosis.

[Simultaneous determination for metabolites of benzene compounds in urine by high performance liquid chromatography].

Objective: To describe for the determination of contents of metabolites of benzene compounds in urine sample by high performance liquid chromatography. Methods: After acidification with hydrochloric acid, metabolites in urine were first extracted by acetonitrile and isopropanol (V∶V, 9∶1) with excessive sodium chloride, then gradient separated on a C18 column and then determined by DAD detector. Results: There were good linear relationship between peak areas and injection quality in range of 2.00-100 mg/L (r>0.999). The detection limit and quantitative limit of this method were 4.15-70.7 µg/L and 13.8-235 µg/L respectively. The precision for the analysis of urine was1.78%-8.23% (n =6). The average recovery of metabolites was 85.4%-105.5% at thee spiked levels in the range of 2.00-100 mg/L. Conclusion: The accuracy and reproducibility obtained make this method useful for the biological monitoring of occupational exposure to toluene, xylene, styrene and ethylbenzene.

[Comparison of whole blood indium and the serum indium of the population exposed to the indium].

Objective: The method was established for the detection of whole blood indium and serum indium. By comparing the results of two samples, it is possible to explore the significance of whole blood indium and serum indium in the population exposed to indium compounds. Methods: According to GBZ/T 295-2017 and GBZ 294-2017, the whole blood and serum samples were diluted 20 times by 0.5% nitric acid solution (including 0.05% Triton X-100) . Under the standard mode of inductively coupled plasma mass spectrometry (ICP-MS) , whole blood indium and serum indium of indirect exposure group, low exposure group and high exposure group in an indium mine were detected with 20 µg/L rhodium standard solution as internal standard. Results: This method has a working range of 0.00~5.00 µg/L and a correlation coefficien t>0.999. The detection limit and quantitative lower limit of whole blood indium were 0.076 µg/L and 0.26 µg/L respectively. Those of serum indium were 0.06 µg/L and 0.20 µg/L accordingly. The recovery rates of serum and whole blood samples were 88.5%~95.6% and 93.0%~101%. Intra batch precisions were 1.3%~4.4% and 1.9%~3.5% and inter batch precision were 2.4%~6.1% and 2.1%~4.6% in two samples. There were no significant differences between whole blood indium and serum indium in indirect exposure group. The serum indium level was lower than the detection limit in 3 cases, while their whole blood indium was only below the quantitative lower limit. However, in other groups whole blood indium level was significantly higher than serum indium level (P<0.05) and even was two-fold in the high exposure group. Conclusion: The detection of whole blood indium is more sensitive than that of serum indium, which can reflect the internal exposure level more accurately in exposure population. Therefore, the whole blood indium is of more important referential value to health examination and poisoning diagnosis in the population exposed to indium and its compounds.

[Rasmussen syndrome: a clinicopathologic study of four cases].

Objective: To investigate the clinicopathologic features of Rasmussen syndrome (RS) and to raise awareness of this rare disease. Methods: Clinicopathologic data of 4 cases of RS were retrospectively analyzed at Beijing Haidian Hospital from 2008 to 2016. Results: The clinical manifestations included epilepsia partialis continua and progressive neurologic deficits in all patients.MRI demonstrated unihemispheric focal cortical atrophy in all cases. The histopathologic changes included variable degrees of lymphocytic infiltrate within the cortex, subarachnoid space and perivascular cuffing.Microglial nodules and neuronophagia were seen. Mild to severe neuronal loss was noted with variable degrees of reactive gliosis. Spongy edema and cavitation were observed in focal cortex. Inflammation involving hippocampus was seen in one case. Three cases were accompanied by focal cortical dysplasia (FCD) Ⅲd. Immunohistochemical staining showed that the infiltrative lymphocytes were positive for CD3, CD8, granzyme B and TIA1 and the proliferating microglial cells were positive for CD68. NeuN positive neurons decreased significantly and reactive astrocytes were GFAP positive. Conclusions: Pathologic changes of RS are similar to viral encephalitis and the inflammation is progressive and multifocal involving the hemisphere. The diagnosis of RS relies on pathologic features combined with clinical findings and neuroradiological examinations.

Density-dependent survival varies with species life-history strategy in a tropical forest.

Species coexistence in diverse communities likely results from multiple interacting factors. Mechanisms such as conspecific negative density dependence (CNDD) and varying life-history strategies related to resource partitioning are known to influence plant fitness, and thereby community composition and diversity. However, we have little understanding of how these mechanisms interact and how they vary across life stages. Here, we document the interaction between CNDD and life-history strategy, based on growth-mortality trade-offs, from seedling to adult tree for 47 species in a tropical forest. Species' life-history strategies remained consistent across stages: fast-growing species had higher mortality than slow-growing species at all stages. In contrast, mean CNDD was strongest at early life stages (i.e. seedling, sapling). Fast-growing species tended to suffer greater CNDD than slow-growing species at several, but not all life stages. Overall, our results demonstrate that coexistence mechanisms interact across multiple life stages to shape diverse tree communities.

Backcrosses to Brassica napus of hybrids between B. juncea and B. napus as a source of herbicide-resistant volunteer-like feral populations.

Introgression between genetically modified (GM) crops and wild relatives is considered to potentially modify the genetic background of the wild species. The emergence of volunteer-like feral populations through backcross of hybrids to the crop is also a concern. The progeny of spontaneous hybrids between mutant herbicide-resistant oilseed rape (Brassica napus) and wild B. juncea was obtained. Parents, F(2) and BC(1) to B. napus were planted together in the field so as to study their performance. The chromosome number of BC(1) followed a Normal distribution. Mendelian ratio of the herbicide-resistance gene was found. The F(2) produced less seeds than B. napus, and BC(1) had intermediate production. Herbicide-resistant BC(1) were not different of their susceptible counterparts for plant weight, seed weight and seed number, but most of them exhibited B. napus morphology and larger flowers than the susceptible BC(1). They displayed an important genetic variability allowing further adaptation and propagation of the herbicide-resistance gene. Pollen flow to susceptible plants within the mixed stand was observed. As a consequence, the resistant BC(1) produced with B. napus pollen could frequently occur and easily establish as a false feral crop population within fields and along roadsides.

Correlated expression of gfp and Bt cry1Ac gene facilitates quantification of transgenic hybridization between Brassicas.

Gene flow from transgenic oilseed rape (BRASSICA NAPUS) might not be avoidable, thus, it is important to detect and quantify hybridization events with its relatives in real time. Data are presented showing the correlation between genetically linked green fluorescent protein (GFP) with BACILLUS THURINGIENSIS (Bt) CRY1AC gene expression in hybrids formed between transgenic B. NAPUS "Westar" and a wild Chinese accession of wild mustard (B. JUNCEA) and hybridization between transgenic B. NAPUS and a conspecific Chinese landrace oilseed rape. Hybrids were obtained either by spontaneous hybridization in the field or by hand-crossing in a greenhouse. In all cases, transgenic hybrids were selected by GFP fluorescence among seedlings originating from seeds harvested from B. JUNCEA and the Chinese oilseed rape plants. Transgenicity was confirmed by PCR detection of transgenes. GFP fluorescence was easily and rapidly detected in the hybrids under greenhouse and field conditions. Results showed that both GFP fluorescence and Bt protein synthesis decreased as either plant or leaf aged, and GFP fluorescence intensity was closely correlated with Bt protein concentration during the entire vegetative lifetime in hybrids. These findings allow the use of GFP fluorescence as an accurate tool to detect gene-flow in time in the field and to conveniently estimate BT CRY1AC expression in hybrids on-the-plant.