巴西橡胶树HbSIP2互作蛋白的筛选和鉴定

可溶性无机焦磷酸酶在天然橡胶生物合成中具有重要的调控作用,HbSIP2是胶乳中关键的可溶性无机焦磷酸酶基因。为了深入了解HbSIP2调控橡胶生物合成的机理,本研究对HbSIP2互作蛋白进行了筛选和鉴定。结果表明:诱饵载体p GBKT7-Hb SIP2无自激活活性,且对酵母无毒性作用,可以用于酵母文库筛选。将诱饵载体与橡胶树胶乳cDNA文库进行杂交,初步筛选获得20个与HbSIP2互作的蛋白。进一步通过双分子荧光互补实验证实,Hb SIP2能够与橡胶延伸因子发生蛋白互作。本研究结果为HbSIP2调控橡胶生物合成的机理研究提供了重要的理论依据。     

3种酰胺类稻田除草剂对克氏原螯虾的急性毒性

[目的] 研究稻虾共作模式条件下,稻田封闭除草剂对克氏原螯虾产生的急性毒性。[方法] 采用半静态试验方法,研究3种酰胺类除草剂（乙草胺、丙草胺和丁草胺）对克氏原螯虾的急性毒性,计算3种酰胺类除草剂对克氏原螯虾的安全浓度,并分析其LC₅₀衰减规律。[结果] 随着暴露时间和除草剂浓度的增加,虾体侧躺,步行足和游泳足活动频率降低,最终死亡。乙草胺对克氏原螯虾的96 h半致死浓度（LC₅₀）和安全浓度（SC）分别为0.0707和0.0146 mL·L^-1;丙草胺对克氏原螯虾的96 h LC₅₀和SC分别为0.0119和0.0021 mL·L^-1;丁草胺对克氏原螯虾的96h LC₅₀和SC分别为0.0073和0.0014 mL·L^-1。乙草胺、丙草胺及丁草胺除草剂LC₅₀随着暴露时间延长呈下降趋势,符合双曲线衰减模型,回归方程分别为：① y₁=2.0840x^-0.7380（R²=0.9973）;② y₂=0.1106x^-0.4930（R²=0.9872）;③ y₃=0.2236x^-0.7480（R²=0.9990）。克氏原螯虾对3种除草剂的敏感性由高到低依次为：丁草胺 > 丙草胺 > 乙草胺。[结论] 乙草胺和丙草胺可在稻田综合种养生产过程中按常规剂量使用,而丁草胺按常规剂量使用可能存在较大的风险。     

Novel distribution of calreticulin to cardiomyocyte mitochondria and its increase in a rat model of dilated cardiomyopathy

Background

Calreticulin (CRT), a Ca²⁺-binding chaperone of the endoplasmic reticulum, can also be found in several other locations including the cytosol, nucleus, secretory granules, the outer side of the plasma membrane, and the extracellular matrix. Whether CRT is localized at mitochondria of cardiomyocytes and whether such localization is affected under DCM are still unclear.

Methods and results

The DCM model was generated in rats by the daily oral administration of furazolidone for thirty weeks. Echocardiographic and hemodynamic studies demonstrated enlarged left ventricular dimensions and reduced systolic and diastolic function in DCM rats. Immuno-electron microscopy and Western blot showed that CRT was present in cardiomyocyte mitochondria and the mitochondrial content of CRT was increased in DCM hearts (P < 0.05). Morphometric analysis showed notable myocardial apoptosis and mitochondrial swelling with fractured or dissolved cristae in the DCM hearts. Compared with the control group, the mitochondrial membrane potential level of the freshly isolated cardiac mitochondria and the enzyme activities of cytochrome c oxidase and succinate dehydrogenase in the model group were significantly decreased (P < 0.05), and the myocardial apoptosis index and the caspase activities of caspase-9 and caspase-3 were significantly increased (P < 0.05). Pearson linear correlation analysis showed that the mitochondrial content of CRT had negative correlations with the mitochondrial function, and a positive correlation with myocardial apoptosis index (P < 0.001). The protein expression level of cytochrome c and the phosphorylation activity of STAT3 in the mitochondrial fraction were significantly decreased in the model group compared with the control group (P < 0.05).

Conclusions

These data demonstrate that CRT is localized at cardiomyocyte mitochondria and its mitochondrial content is increased in DCM hearts.     

Complete Radiofrequency Ablation of Hepatolithiasis-Associated Cholangiocarcinoma and Successful Management of Post-ablation Bronchobiliary Fistula

This report documented the use of radiofrequency ablation (RFA) in the treatment of hepatolithiasis-associated cholangiocarcinoma and cyanoacrylate glue in the management of post-ablation bronchobiliary fistula. A 47-year-old Chinese woman with 20 years history of extrahepatic and intrahepatic cholangiolithiasis and multiple hepatic segmentectomy, developed hepatolithiasis-associated cholangiocarcinoma. The tumor was successfully treated with RFA but patient developed bronchobiliary fistula. Cyanoacrylate glue was used for occluding the bronchobiliary fistula. CT scan at 3 months showed complete restoration of physiological separation between the biliary and bronchial system. Repeat CT scan showed complete tumor ablation with no signs of tumor recurrence 10 months after RFA. In conclusion, RFA may be a safe and effective treatment option for patients with hepatolithiasis-associated cholangiocarcinoma who are poor candidates for surgical resection. Protection of the integrity of the bile duct and diaphragm during RFA can minimize postoperative complications. In case of development of post-ablation bronchobiliary fistula, cyanoacrylate glue can be used to occlude the fistula, before surgical resection is considered.     

Excess Body Mass Index and Risk of Liver Cancer: A Nonlinear Dose-Response Meta-Analysis of Prospective Studies

Background

Excess body weight measured as body mass index (BMI) has a positive association with risk of common cancers. However, previous meta-analyses related to BMI and liver cancer had inconsistent results. The purpose of the current study is to establish a nonlinear dose-response relationship between BMI and incidence risk of liver cancer.

Methods

A systematic literature search for relevant articles published from 1966 to November 2011 was conducted in PUBMED and EMBASE digital databases. Additional articles were manually searched by using the reference lists of identified papers. Restricted cubic splines and generalized least-squares regression methods were used to model a potential curvilinear relationship and to make a dose-response meta-analysis. Stratified analysis, sensitivity analysis and assessment of bias were performed in our meta-analysis.

Results

8 articles including 1,779,471 cohort individuals were brought into meta-analysis. A non-linear dose-response association between BMI and risk of liver cancer was visually significant (P for nonlinearity<0.001), besides, the point value of BMI also enhanced the results quantitatively, where relative risks were 1.02 (95%CI = 1.02–1.03), 1.35 (95%CI = 1.24–1.47) and 2.22-fold (95%CI = 1.74–2.83) when BMI was at the point of 25, 30 and 35 kg/m² compared with reference (the median value of the lowest category), respectively. The ethnicity of the population was found as the main source of heterogeneity. In subsequent stratified analysis, no evidence of heterogeneity was showed in Asian and White populations (P for heterogeneity>0.1), and all value of BMI still presented significantly increased risk of cancer.

Conclusions

The findings from meta-analysis provided that excess BMI had significant increased association with risk of liver cancer, although the biological mechanisms underlying the obesity-cancer link still need to be clarified.     

BK Channel Deficiency in Osteoblasts Reduces Bone Formation via the Wnt/β-Catenin Pathway

Global knockout of the BK channel has been proven to affect bone formation; however, whether it directly affects osteoblast differentiation and the mechanism are elusive. In the current study, we further investigated the role of BK channels in bone development and explored whether BK channels impacted the differentiation and proliferation of osteoblasts via the canonical Wnt signaling pathway. Our findings demonstrated that knockout of Kcnma1 disrupted the osteogenesis of osteoblasts and inhibited the stabilization of β-catenin. Western blot analysis showed that the protein levels of Axin1 and USP7 increased when Kcnma1 was deficient. Together, this study confirmed that BK ablation decreased bone mass via the Wnt/β-catenin signaling pathway. Our findings also showed that USP7 might have the ability to stabilize the activity of Axin1, which would increase the degradation of β-catenin in osteoblasts.     

Purification and characterization of extracellular cholesterol oxidase from <Emphasis Type="Italic">Enterobacter</Emphasis> sp.

The objective of this work is to obtain an abundant source of cholesterol oxidases for industrial and medicinal needs. Thirteen bacterial strains that express high level of inducible extracellular cholesterol oxidase (COX) were isolated from carnivore feces. One of these strains, named COX8-9, belonging to the genus Enterobacter, was found to produce the highest level of cholesterol oxidase. COX from strain COX8-9 was purified from the culture supernatant by ultrafiltration followed with two consecutive Q-Sepharose chromatographies at different pH values, and then by Superdex-75 gel filtration. The purified enzyme was a monomer with a molecular weight of 58 kDa, and exhibited maximum absorption at 280 nm. The K _m value for oxidation of cholesterol by this enzyme was 1.2 × 10⁻⁴ M, with optimum activity at pH 7.0. Enzymatic activity of COX was enhanced 3-fold in the presence of metal ion Cu²⁺, and the enzyme was stable during long-term aqueous storage under various temperatures, indicating its potential as a clinical diagnostic reagent. Preparation and characterization of cholesterol oxidases from the other selected strains are under way. Deping Ye and Jiahong Lei are contributed equally to this work.     

The Diagnostic Value of Tumor Biomarkers for Detecting Hepatocellular Carcinoma Accompanied by Portal Vein Tumor Thrombosis

Tumor biomarkers commonly used for the detection of hepatocellular carcinoma (HCC) complicated with portal vein tumor thrombosis (PVTT) do not show satisfactory sensitivity and specificity. This study assesses the diagnostic value of the tumor biomarkers for the diagnosis of HCC with PVTT. A retrospective study was conducted on 475 patients diagnosed as HCC with PVTT and 977 patients diagnosed with HCC by imaging and requiring surgery at our hospital from January 1993 to January 2011. Serum alpha-fetoprotein AFP, carcinoembryonic antigen, and cancer antigen 125 (Ca125) of the patients were studied. No significant differences were observed in the patients’ general characteristics. The receiver operating characteristic (ROC) analysis showed that the cut-off of AFP and Ca125 was 32.91 ng/ml and 113.65 U/ml, respectively (AUC = 0.814 and 0.783). The parallel testing with AFP and Ca125 has a sensitivity of 0.909 and a specificity of 0.410; the serial testing has a sensitivity of 0.520 and a specificity of 0.97. The condition of AFP ≥ 20,000 ng/ml can detect HCC with PVTT with a sensitivity of 0.24, a specificity of 0.96, and an accuracy of 0.73 and positive screening of 0.76. The standard of both AFP > 32.91 ng/ml and Ca125 > 113.65 U/ml or AFP ≥ 20,000 ng/ml can detect HCC with PVTT with a specificity of 0.97 and 0.96, respectively, providing important guidance for clinical practice.