Serum Uric Acid Relation for Hearing Threshold Shift

OBJECTIVES: The effects of serum uric acid (UA) level on a variety of diseases were found from experimental and observational studies via oxidative stress and anti-oxidants. However, research on the association of UA and hearing thresholds is relatively sparse. We investigated this issue in the U.S. general population to evaluate the relationship of serum UA levels and pure tone threshold of hearing. METHODS: Forty four thousand eighty four eligible participants aged 20 to 69 years who have serum UA data and received Audiometry Examination Component were enrolled from the National Health and Nutrition Examination Survey 1999–2004. Hearing thresholds (dB) as a pure tone average at low frequencies (0.5, 1, 2 kHz) and at high frequencies (3, 4, 6, and 8 kHz) were computed. Multivariate linear regression models and tertile-based analysis with an extended-model approach for covariates adjustment were used to assess the correlation between serum UA level and hearing thresholds. RESULTS: In the adjusted mode of tertile-based analysis, the regression coefficients elucidated as the change of log-transformed mean hearing thresholds upon comparing participants in the highest tertile of serum UA to those in the lowest tertile were –0.067 (P=0.023) in high frequency and –0.058 (P=0.054) in low frequency. After adjusting for multiple pertinent covariates, inverse association between tertiles of serum UA and hearing thresholds remained essentially unchanged. The negative trends between serum UA and hearing thresholds were statistically significant (P for trends <0.05) in tertile-based multiple linear regressions. CONCLUSION: Individuals with elevated UA levels independently were found to be inversely associated with hearing thresholds for pure tone audiometry in a nationally representative sample of U.S. adults.

Effects of pyrrolidine dithiocarbamate on expressions of α-smooth muscle actin, integrin α5 and fibronectin in acute paraquat poisoned rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To observe the expressions of α-SMA, integrin α5 and fibronectin (Fn) in acute paraquat poisoned rats and the effect of PDTC. To investigate the mechanism of paraquat-induced pulmonary fibrosis.</p><p><b>METHODS</b>Sprague-Dawley rats were randomly divided into three experimental groups: Control group (6 rats), PQ group (36 rats) and PQ+PDTC group (36 rats). On the 1st, 3rd, the 7th, the 14th, the 28th and the 56th day after exposure, the protein expression of α smooth muscle actin (α-SMA) was evaluated by western blot. The mRNA levels of integrin α5 and fibronectin (Fn) were analyzed with real-time quantitative PCR (RT-PCR). Meanwhile, the lung pathological changes were observed and semi-quantified.</p><p><b>RESULTS</b>T With the time passing, the expression of α-SMA in PQ group increased gradually compared with control group (P < 0.05 or P < 0.01). The increasing extent was gently on the 3 rd, the 7 th day. While increasing extent was rapidly from the 28 th to the 56 th day. RT-PCR showed PQ significantly increased Fn mRNA level on all time points and increased integrin α5 mRNA level from the 7 rd to 56 th day compared with control group (P < 0.05 or P < 0.01). PDTC treatment significantly deceased α-SMA, Fn, and integrin α5 levels compared with PQ group in corresponding time points (P < 0.05 or P < 0.01) Noteworthy, in PQ+PDTC group, the occurrence of pathological changes were drastically attenuated and pathologic score significantly decreased (P < 0.05 or P < 0.01).</p><p><b>CONCLUSIONS</b>α-SMA, integrin α5 and fibronectin could play an important role in the development of pulmonary fibrosis caused by paraquat poisoning. PDTC, asa strong NF-κB inhibitor, may inhibit NF-κB activity and further significantly decreased expressions of α-SMA, integrin α5 and fibronectin which were important part of ECM, leading to drastically attenuated pulmonary fibrosis. However, the mechanisms of PDTC intervention still remains to be explored.</p>

Current situation of awareness and use of banned pesticides among vegetable greenhouse farmers in a town of Ledu County, China / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the awareness and use of banned pesticides among vegetable greenhouse farmers in a town of Ledu County, Qinghai Province, China and to provide a basis for the management and control of banned pesticides.</p><p><b>METHODS</b>Local residents who lived in a town of Ledu County for more than 5 years were selected as subjects in August 2012. A questionnaire survey was conducted in 267 vegetable greenhouse farmers who were selected from five villages of the town by cluster random sampling.</p><p><b>RESULTS</b>Of the 267 subjects, 249 (93.26%) completed and returned the questionnaires. Eighty-seven (34.9%) of the 249 subjects were aware of banned pesticides, and the banned pesticide awareness rate varied significantly among the subjects with different education levels (χ(2) = 11.061, P = 0.011). Only education level entered the regression equation in non-conditional logistic regression analysis. Only five (2.0%) of the 249 subjects knew the banned pesticides as well as the details. All the 249 subjects used banned pesticides to varying degrees in the past 5 years. Only 9.0% (17/189) of the vegetable greenhouse farmers knew the time pesticides were initially banned in China.</p><p><b>CONCLUSION</b>The banned pesticide awareness rate is relatively low in the town of Ledu County, and this rate is influenced by education level. It is needed to spread the knowledge and hazards of banned pesticides.</p>

Intervention of pyrrolidine dithiocarbamate on expressions of connective tissue growth factor, type I collagen, and type III collage in acute paraquat poisoned rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To observe the changes in the expression of connective tissue growth factor (CTGF), type I collagen (Col I), and type III collagen (Col III) among the rats with acute paraquat (PQ) poisoning and the intervention effect of pyrrolidine dithiocarbamate (PDTC) on their expression, and to investigate the mechanism of PQ-induced pulmonary fibrosis and the intervention effect of PDTC on the disease.</p><p><b>METHODS</b>Sprague-Dawley rats were randomly divided into control group (n = 6), PQ group (n = 36), and PQ + PDTC group (n = 36). The PQ group and PQ + PDTC group were given a single dose of saline-diluted PQ (80 mg/kg) by gavage; 2 h later, the PQ + PDTC group was intraperitoneally injected with a single dose of PDTC (100 mg/kg), and the PQ group was intraperitoneally injected with the same amount of saline. The control group was given saline (1 ml/kg) by gavage and was intraperitoneally injected with the same amount of saline 2h later. At 1, 3, 7, 14, 25, and 56 days after operation, the protein expression of CTGF was evaluated by Western blot; the mRNA expression of CTGF, Col I, and Col III was analyzed by real-time quantitative PCR; the content of hydroxyproline in lung tissue was measured, and the pathological changes of lung tissue of the poisoned rats were observed.</p><p><b>RESULTS</b>The protein expression of CTGF in the PQ group increased as the time went on, slowly from the 3rd to the 14th day and rapidly from the 28th to the 56th day, significantly higher than that in the control group at each time point (P < 0.05 or P < 0.01). The mRNA expression of CTGF in the PQ group began to rise markedly on the 1st day, increased rapidly from the 3rd to the 14th day, and remained at a relatively high level from the 28th to the 56th day, significantly higher than that in the control group at each time point (P < 0.01). The mRNA expression of Col I in the PQ group changed little on the 1st and 3rd day, increased slightly on the 7th day, and increased greatly from the 14th to the 56th day, significantly higher than that in the control group from the 7th to the 56th day (P < 0.05 or P < 0.01). The mRNA expression of Col III in the PQ group began to rise on the 1st day, reached the peak level on the 7th day, and then declined, significantly higher than that in the control group at each time point (P < 0.05 or P < 0.01). Masson staining showed that fibroblasts proliferated from the 14th to the 28th day, and collagen fibers increased gradually. Compared with the PQ group, the PQ + PDTC group showed significantly decreased protein expression of CTGF as well as mRNA expression of CTGF, Col I, and Col III (P < 0.05 or P < 0.01).</p><p><b>CONCLUSION</b>In PQ-induced pulmonary fibrosis, the expression of CTGF keeps rising, and the collagen secretion and matrix synthesis are increased probably by upregulating the transcriptional levels of Col I and Col III; CTGF plays an important role in PQ-induced pulmonary fibrosis. PDTC can inhibit the expression of CTGF, thus reducing the lung injury in rats with PQ poisoning.</p>

Osteogenic differentiation of murine yolk sac mesenchymal stem cells in vitro / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the potential of yolk sac mesenchymal stem cells in osteogenic differentiation.</p><p><b>METHODS</b>Murine yolk sacs were harvested on day 8.5 postcoitus, yolk sac cells were obtained after the yolk sacs were digested by 0.1% type I collagenase for 1 hour, the non-adherent cells were removed after being cultured for 1 hour. The adherent cells were cultured in DMEM containing of 5 ng/ml bFGF and 15% FBS, and passaged when they became subconfluent. The morphologic characteristics, and AKP, BMP-2, as well as type I, III collagen of the yolk sac adherent cells were observed and tested. The attached cells were treated with 10(-8) mol/L dexamethasone, 10 mmol/L beta-glycerophosphate, and 50 micrograms/ml vitamin C at passage 4. Alternations of morphological characteristic, AKP activity, collagen of type I, III and mineralization were detected.</p><p><b>RESULTS</b>Pure mesenchymal stem cells which were of spindle shape, uniform in size, positive in type I, III collagen staining and weak positive in AKP activity could be induced to pleomorphism osteoblast-like cells in vitro. The cells were transformed from spindle shape to polygonal cells which were positive in type I collagen, negative in type III collagen, strong positive in BMP-2, and positive in Von Kossa's stain at week 8. The polygonal cells could form nodular structure and their AKP activity was increased. All these were coincidence with the characters of osteoblast.</p><p><b>CONCLUSION</b>Yolk sac mesenchymal stem cell can be purified and induced to osteoblast in vitro.</p>