MDM2 is implicated in high‐glucose‐induced podocyte mitotic catastrophe via Notch1 signalling

Podocyte injury and depletion are essential events involved in the pathogenesis of diabetic nephropathy (DN). As a terminally differentiated cell, podocyte is restricted in ‘post‐mitosis’ state and unable to regenerate. Re‐entering mitotic phase will cause podocyte disastrous death which is defined as mitotic catastrophe (MC). Murine double minute 2 (MDM2), a cell cycle regulator, is widely expressed in renal resident cells including podocytes. Here, we explore whether MDM2 is involved in podocyte MC during hyperglycaemia. We found aberrant mitotic podocytes with multi‐nucleation in DN patients. In vitro, cultured podocytes treated by high glucose (HG) also showed an up‐regulation of mitotic markers and abnormal mitotic status, accompanied by elevated expression of MDM2. HG exposure forced podocytes to enter into S phase and bypass G2/M checkpoint with enhanced expression of Ki67, cyclin B1, Aurora B and p‐H3. Genetic deletion of MDM2 partly reversed HG‐induced mitotic phase re‐entering of podocytes. Moreover, HG‐induced podocyte injury was alleviated by MDM2 knocking down but not by nutlin‐3a, an inhibitor of MDM2‐p53 interaction. Interestingly, knocking down MDM2 or MDM2 overexpression showed inhibition or activation of Notch1 signalling, respectively. In addition, genetic silencing of Notch1 prevented HG‐mediated podocyte MC. In conclusion, high glucose up‐regulates MDM2 expression and leads to podocyte MC. Notch1 signalling is an essential downstream pathway of MDM2 in mediating HG‐induced MC in podocytes.     

Carbenoxolone inhibits TRPV4 channel‐initiated oxidative urothelial injury and ameliorates cyclophosphamide‐induced bladder dysfunction

Carbenoxolone (CBX) is a clinically prescribed drug for the treatment of digestive ulcer and inflammation. It is also a widely used pharmacological inhibitor of several channels in basic research. Given that the overactivity of several channels, including those inhibitable by CBX, underlies bladder dysfunction, we tested the potential therapeutic application and mechanism of CBX in the treatment of voiding dysfunction. In a mouse model of cystitis induced by cyclophosphamide (CYP), CBX administration prevented the CYP‐elicited increase in bladder weight, oedema, haemorrhage, and urothelial injury. CBX also greatly improved micturition pattern, as manifested by the apparently decreased micturition frequency and increased micturition volume. Western blot results showed that CBX suppressed CYP‐induced increase in protein carbonyls, COX‐2, and iNOS. Further analysis using cultured urothelial cells revealed that acrolein, the major metabolite of CYP, caused protein oxidation, p38 activation, and urothelial injury. These effects of acrolein were reproduced by TRPV4 agonists and significantly prevented by antioxidant NAC, p38 inhibitor SB203580, TRPV4 antagonist RN‐1734, and CBX. Further studies showed that CBX potently suppressed TRPV4 agonist‐initiated calcium influx and subsequent cell injury. CBX attenuated CYP‐induced cystitis in vivo and reduced acrolein‐induced cell injury in vitro, through mechanisms involving inhibition of TRPV4 channels and attenuation of the channel‐mediated oxidative stress. CBX might be a promising agent for the treatment of bladder dysfunction.     

Antioxidant Activity and α-Glucosidase Inhibitory Activities of the Polycondensate of Catechin with Glyoxylic Acid

In order to investigate polymeric flavonoids, the polycondensate of catechin with glyoxylic acid (PCG) was prepared and its chemically antioxidant, cellular antioxidant (CAA) and α-glucosidase inhibitory activities were evaluated. The DPPH and ABTS radical scavenging activities and antiproliferative effect of PCG were lower than those of catechin, while PCG had higher CAA activity than catechin. In addition, PCG had very high α-glucosidase inhibitory activities (IC₅₀ value, 2.59 μg/mL) in comparison to catechin (IC₅₀ value, 239.27 μg/mL). Inhibition kinetics suggested that both PCG and catechin demonstrated a mixture of noncompetitive and anticompetitive inhibition. The enhanced CAA and α-glucosidase inhibitor activities of PCG could be due to catechin polymerization enhancing the binding capacity to the cellular membrane and enzymes.     

Screening and Identification of Marburg Virus Entry Inhibitors Using Approved Drugs

正Dear Editor,Marburg virus(MARV) belongs to the Filoviridae family,along with the related Ebola virus(EBOV). Although MARV is less renowned than EBOV, it causes an equally devastating disease, with clinical symptoms similar to EBOV infection and a remarkably high mortality rate. To     

Observations on the division characterization of diploid nuclear in <Emphasis Type="Italic">Porphyra</Emphasis> (Bangiales,Rhodophyta)

Nuclear divisions of carpospores, conchocelis and conchospores of Porphyra yezoensis, P. haitanensis, P. katadai var. hemiphylla and P. oligospermatangia from China were investigated. The observations showed diploid chromosome numbers of 2n = 6 for P. yezoensis and P. oligospermatangia, and 2n = 10 for P. haitanensis and P. katadai var. hemiphylla. For all four species, somatic pairing of chromosome sets was observed in late prophase. Sister chromosomes separated at anaphase as mitosis took place in carpospores, conchocelis filamentous cells, conchosporangial branch cells and sporangial cells (conchospore formation). Chromosome configurations of tetrad and ring-shaped in conchospore germination were observed, demonstrating the occurrence of meiosis. The characteristics of diploid nuclear division in 2n = 6 species are the same as those of 2n = 10 species. The influence of somatic pairing on nuclear division of diploid cells in Porphyra was discussed.     

崇明东滩人工湿地越冬水禽行为观察

2006年12月上旬-2007年2月下旬,在崇明东滩堤内次生人工湿地(鱼-蟹塘)对7种优势种水禽的昼间(6:30-17:30)行为进行了观察.结果表明:白鹭(Egrettagarzetta)、苍鹭(Ardea cinerea)和斑嘴鸭(Anas poecilorhyncha)以停伫行为为主,分别占全天行为的34.09%、45.45%和54.55%;白骨顶(Fulica atra)、普通鸬鹚(Phalacrocorax carbo)取食行为较活跃,分别占全天行为的32.58%和35.00%;小鹛鹧(Tachybaptus ruficollis)和银鸥(Larus argentatus)游水活动分别占全天行为的44.70%和31.82%.此外,环境温度和光照与水禽活动呈正相关,与风速负相关,湿地内水位由于变化不大而对越冬水禽行为影响不显著.     

血清肿瘤标志物CEA、CA199及CA153联合检测对肺癌的诊断价值

目的：评价血清CEA、CA199及CA153联合检测对肺癌诊断及分期的临床价值。方法：用化学发光分析法测定144例不同类型及分期的肺癌患者、92例肺良性疾病患者及76例健康体检者血清CEA、CA199及CA153水平的变化。结果：肺癌组血清CEA、CA199及CA153水平均高于正常对照组及肺良性疾病患者，有显著性差异，且TNM分期越晚，其水平越高；3项肿瘤标志联合检测可提高敏感性及准确性。结论：CEA、CA199及CA153联合检测可以为肺癌的诊断及分期提供有价值的实验室依据。     

非神经元型胆碱能系统在（前）脂肪细胞的表达及nAChRα7功能状态对前脂肪细胞Visfatin基因表达的影响

原核生物、真核生物、植物体的非神经细胞和组织中，尤其是多种免疫活性细胞中,均证实乙酰胆碱酯酶（acetylcholinesterase，AChE）、胆碱乙酰转移酶（choline acetyltransferase，ChAT）和乙酰胆碱受体（acetylcholine receptor, AChR）各亚型在内的胆碱能系统组分的存在，其中烟碱样乙酰胆碱受体α7（nicotinic acetylcholine receptor α7，nAChRα7）是烟碱样胆碱能抗炎通路（nicotinic anti-inflammatory pathway）中重要的分子核心机制，同时也是机体限制宿主防御反应扩大的内源性抗炎机制之一. 本文旨在探讨（前）脂肪细胞上非神经元型胆碱能系统是否存在及初步揭示烟碱样胆碱能受体α7对前脂肪细胞功能的影响. 以体外培养的3T3-L1前脂肪细胞为研究对象，采用免疫组化和蛋白质免疫印迹技术,分别检测前脂肪细胞和成熟脂肪细胞中乙酰胆碱酯酶、胆碱乙酰转移酶和烟碱样乙酰胆碱受体α7的3种胆碱能系统主要组分的蛋白表达. 另将前脂肪细胞分为给予广谱烟碱样乙酰胆碱受体激动剂尼古丁、特异性烟碱样乙酰胆碱受体α7激动剂氯化胆碱及特异性烟碱样乙酰胆碱受体α7拮抗剂甲基牛扁亭碱干预12 h、24 h、36 h，并设立相应处理时间的空白对照组，逆转录聚合酶链反应检测前脂肪细胞visfatin mRNA表达情况. 免疫组化染色可见前脂肪细胞中AChE、ChAT及AChRα7均有阳性表达；蛋白免疫印迹检测进一步半定量证实了前脂肪细胞和成熟脂肪细胞中AChE、ChAT及AChRα7的蛋白表达；拮抗剂甲基牛扁亭碱(10⁶～10⁴mol/L)时间、剂量依赖性上调前脂肪细胞visfatin mRNA表达(1.3～1.55fold,P<0.01)，与对应空白对照组相比,存在显著性统计学差异; 加入不同剂量的尼古丁和氯化胆碱,则前脂肪细胞中visfatin mRNA表达水平与对应空白对照组相比,均不同程度地下降,其中以氯化胆碱的抑制效应更为显著. 前脂肪细胞与成熟脂肪细胞中均存在有独立的胆碱能体系，其中AChRα7很可能在调节脂肪细胞因子分泌及肥胖相关的病理生理过程中发挥重要作用.