Glycyrrhizin inhibits the lytic pathway of complement--possible mechanism of its anti-inflammatory effect on liver cells in viral hepatitis

Glycyrrhizin, an aqueous extract of licorice root, has anti-inflammatory activity and has been used for the treatment of chronic viral hepatitis. In the present study we describe the mechanism by which glycyrrhizin inhibits complement. Glycyrrhizin inhibited the cytolytic activity of complement via the activation of both the classical and alternative pathways, while it had no effect on immune adherence, suggesting that it blocks C5 or a later stage of the complement cascade. Further analysis revealed that glycyrrhizin inhibits the lytic pathway in which the membrane attack complex (MAC) is formed. This mechanism suggests that glycyrrhizin may prevent tissue injury caused by MAC not only in chronic hepatitis but in many autoimmune and inflammatory diseases.     

BSCC,Bethesda or other? Terminology in cervical cytology European panel discussion

The European panel agreed that reproducibility and translatability of terminology in cervical cytology were essential, arguing well for harmonization of reporting systems. The majority at this meeting use a modification of the Bethesda system (BS). Local modifications involved reporting subcategories within high grade and low grade lesions, which would not alter the overall translatability of their systems both with each other and BS. The majority agree that low grade lesions with and without koilocytosis should be managed similarly as should high grade lesions (moderate dysplasia/CIN2 or worse). Those systems linking moderate dysplasia with mild rather than severe dysplasia would need to define moderate dysplasia as such, if their results were to be translatable, which would be preferable to their using a different definition of low grade and high grade lesions. Translation between systems might anyway be facilitated by reporting moderate dysplasia as a subcategory within high grade, which was favoured by most of those present. Therefore, there is no need for exact agreement of terminology if broad principles are agreed. This useful discussion adds weight to the British Society for Clinical Cytology recommendation that the new classification should be adopted by the UK National Health Service Cervical Screening Programme. If the new classification is adopted, the UK would join the European consensus opinion on terminology.     

胃粘膜Na~+-K~+-Mg~(2+)-ATPase在适应性细胞保护机制中的作用

本文观察了胃粘膜(Na~+-K~+-Mg~(2+))-ATPase在适应性细胞保护机制中的作用,并分析了其与内源性PG的关系。结果表明,哇巴因(一种(Na~+-K~+-Mg~(2+))-ATPase的抑制剂)可部分抑制胃蛋白酶150U(溶于0.1mol/L盐酸中)和20％乙醇的适应性细胞保护作用,并呈现明显的量效关系。用上述两种弱刺激灌胃后15min,胃粘膜(Na~+-K~+-Mg~(2+))-ATPase活力明显升高,也呈现明显的量效关系。预先给予消炎痛以抑制内源性PG的合成,则可阻断弱刺激所诱发的胃粘膜(Na~+-K~+-Mg~(2+))-ATPase活力的升高;若在此基础上再给予外源性PGE_2,又可解除消炎痛的阻断作用。这些结果说明,弱刺激通过内源性PG,进而促进胃粘膜(Na~+-K~+-Mg~(2+))-ATPase活力升高,使粘膜抵抗损伤的能力增强,可能是其保护作用的重要机制之一。     

米曲霉裂解性多糖单加氧酶的异源表达与性质分析

【目的】裂解性多糖单加氧酶(lytic polysaccharide monooxygenases,LPMOs)是一类以氧化方式断裂多聚糖糖苷键的新型木质纤维素降解酶,本文旨在挖掘新型LPMOs并研究其性质。【方法】从米曲霉中克隆LPMO基因,利用毕赤酵母表达系统进行异源表达,研究其酶学性质和还原剂对其活性的影响,进一步探讨LPMO与糖苷水解酶协同作用时的底物结合现象。【结果】Ao LPMO2和Ao LPMO5序列分析显示,两种蛋白都为辅助酶类9家族的LPMOs;电击转化至真核毕赤酵母GS115中,获得双拷贝转化子GS/AO5-4,经1%甲醇诱导4 d后,上清液蛋白表达量为0.19±0.01 g/L。重组蛋白分子量约34 k Da,高于理论分子量,推测可能存在翻译后修饰。酶学性质分析表明,Ao LPMO5对刺槐豆胶的最适反应温度和p H分别为60°C和5.0,Km和Vmax分别为8.72±1.99 mg/m L和109.4±12.8μmol/(s·mg)。0.1 mmol/L Cu^2+促进酶活性提高(7.10±1.32)%(P<0.05),0.5、2.0和2.5 mmol/L H2O2分别促进酶活性提高(21.11±6.17)%(P<0.01)、(20.22±1.13)%(P<0.01)和(18.40±2.86)%(P<0.01),而没食子酸和维生素C对活性无明显作用。在反应前期,Ao LPMO5与刺槐豆胶底物结合从而影响甘露聚糖酶Bs MAN3的降解作用。而在反应后期,Ao LPMO5与Bs MAN3则表现出协同增效作用。【结论】Ao LPMO5是一种全新的生物质降解酶,阐明其酶学性质和底物作用方式,将为天然木质纤维素类底物的高效转化与生物炼制,如第二代生物乙醇、功能性低聚寡糖等生产建立基础。     

鱼源副乳房链球菌前噬菌体裂解酶Sply828的抗菌活性

【背景】副乳房链球菌（Streptococcus parauberis）是重要的水产病原菌,该病原菌已逐渐出现新的血清型及多重耐药性状,因此亟须开发出一种新的抗菌药物用于该病害的防治。研究发现,前噬菌体编码的裂解酶能够有效地杀死其宿主,具有良好的抗菌应用前景。【目的】以副乳房链球菌前噬菌体裂解酶为对象,研究其杀菌宿主谱并优化其裂解活性的条件。【方法】利用PHASTER工具对副乳房链球菌菌株KRS02083全基因组序列分析发现,其前噬菌体包含一种裂解酶的基因Sply828;通过基因克隆、表达和纯化等技术得到裂解酶Sply828蛋白;通过浊度递减实验探究裂解酶Sply828对不同细菌的杀菌活性及其最适的裂解条件。【结果】裂解酶Sply828对鱼源副乳房链球菌具有最佳的杀菌活性,并发现该酶对处于指数生长期的细菌杀菌效果最好;其最适裂解温度为28°C,最适pH为6.2;Ca²⁺和Mg²⁺对该酶的杀菌活性有促进作用,但是Zn²⁺、Cu²⁺、Fe²⁺、Ni²⁺明显抑制...     

Trypanosoma congolense: paraoxonase 1 prolongs survival of infected mice

In vitro studies have suggested that a fraction of human high density lipoprotein (HDL), termed trypanosome lysis factor (TLF), can protect against trypanosome infection. We examined the involvement of two proteins located in the TLF fraction, apolipoprotein A-II (apoA-II) and paraoxonase 1 (PON1), against trypanosome infection. To test whether PON1 is involved in trypanosome resistance, we infected human PON1 transgenic mice, PON1 knockout mice, and wild-type mice with Trypanosoma congolense. When challenged with the same dosage of trypanosomes, mice overexpressing PON1 lived significantly longer than wild-type mice, and mice deficient in PON1 lived significantly shorter. In contrast, mice overexpressing another HDL associated protein, apoA-II, had the same survival as wild-type mice. Together, these data suggest that PON1 provides protection against trypanosome infection. In vitro studies using T. brucei brucei indicated that HDL particles containing PON1 and those depleted of PON1 did not differ in their lysis ability, suggesting that protection by PON1 is indirect. Our data are consistent with an in vivo role of HDL protection against trypanosome infection.     

Necrotic Lesions as Unusual Symptoms of Ring Rot in the Potato Leaves

Test-tube plants and suspension cell cultures of two cultivars of the potato (Solanum tuberosum L.) differing in their resistance to ring rot caused by Clavibacter michiganensis subsp. sepedonicus and six strains of this bacterium were used to test the relationship between the virulence, the leaf ability to adsorb bacteria, and the symptoms of the disease. In addition to chlorosis and drying, heavy inoculation with virulent strains caused unusual symptoms, such as leaf necrotic lesions. In the resistant cultivar, the necrotic lesions were predominantly local, whereas in the susceptible cultivar, they expanded. Unlike the susceptible cultivar, suspension cells of the resistant cultivar weakly adhered bacteria of the tested strains. Bacteria entered the plants through the leaf stomata. The sorption and penetration were much more pronounced in the susceptible cultivar. It was concluded that strain virulence varies depending on the conditions of inoculation, and uncharacteristic symptoms (necrotic lesions) arise. The local necrotic lesions are considered a hypersensitive response, and exopolysaccharides of the pathogen as the factors of virulence.     

Millimeter‐wave emissivity as a metric for the non‐contact diagnosis of human skin conditions

A half‐space electromagnetic model of human skin over the band 30–300 GHz was constructed and used to model radiometric emissivity. The model showed that the radiometric emissivity rose from 0.4 to 0.8 over this band, with emission being localized to a layer approximately one millimeter deep in the skin. Simulations of skin with differing water contents associated with psoriasis, eczema, malignancy, and thermal burn wounds indicated radiometry could be used as a non‐contact technique to detect and monitor these conditions. The skin emissivity of a sample of 30 healthy volunteers, measured using a 95 GHz radiometer, was found to range from 0.2 to 0.7, and the experimental measurement uncertainty was ±0.002. Men on average were found to have an emissivity 0.046 higher than those of women, a measurement consistent with men having thicker skin than women. The regions of outer wrist and dorsal forearm, where skin is thicker, had emissivities 0.06–0.08 higher than the inner wrist and volar forearms where skin is generally thinner. Recommendations are made to develop a more sophisticated model of the skin and to collect larger data sets to obtain a deeper understanding of the signatures of human skin in the millimeter wave band. Bioelectromagnetics. 38:559–569, 2017. © 2017 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.     

荧光假单胞菌感染大鲵的病理损伤

通过对感染荧光假单胞菌(Pseudomonas fluorescents)发病的大鲵(Andrias davidianus)主要器官进行病理剖解和病理组织学观察,以明确大鲵感染荧光假单胞菌引起的病理学损伤特点。结果表明,大鲵感染荧光假单胞菌后,主要表现为腹部极度膨胀、腹水和严重胃肠道反应,严重者可见将胃呕吐至口腔;组织器官具有典型的病理变化,其主要靶器官为肾、肝、肠道、皮肤和肌肉。分别引起坏死性肾小球肾炎、肝炎。此外,还可引起轻微肠炎及皮炎。可在肾小管管腔内、肝细胞坏死灶内、肠道固有层内及皮肤肌肉中发现数量极多的杆状细菌。     

胃功能三项联合Hp抗体对胃癌及癌前病变的鉴别诊断价值

目的:探讨胃功能三项联合幽门螺杆菌(Hp)抗体对胃癌及癌前病变的鉴别诊断价值。方法:收集我院2014年5到2017年8月收治的胃癌患者34例(胃癌组)、癌前病变患者46例(癌前病变组),抽取研究对象空腹静脉血5 mL,采用酶联免疫吸附法(ELISA)检测血清胃蛋白酶原-I(PG-I)、血清胃蛋白酶原-II(PG-II),并计算PG-I/PG-II(PGR)值,采用胶体金法或胶乳免疫比浊法检测HP抗体,比较两组胃功能三项及HP抗体阳性率差异,分析胃功能三项联合HP抗体鉴别诊断价值。结果:胃癌组血清PG-Ⅰ和PGR水平低于癌前病变组(P0.05),胃癌组与癌前病变组血清PG-Ⅱ水平、HP抗体阳性率比较差异无统计学意义(P0.05)。胃癌组HP抗体阳性者和阴性者血清PG-Ⅰ、PG-Ⅱ、PGR水平比较差异均无统计学意义(P0.05),癌前病变组HP抗体阳性者血清PG-Ⅰ水平明显低于HP抗体阴性者,差异具有统计学意义(P0.05)。并联检查胃癌和癌前病变的准确度分别为67.6%(23/34)、43.5%(20/46),高于串联的14.7%(5/34)、6.5%(3/46),差异具有统计学意义(P0.05)。结论:Hp感染可能导致PG-Ⅰ降低,具有癌前病变风险,再降低可能具有胃癌风险,临床上根据胃功能三项筛检早期胃癌并且辅助HP检测可早期诊断胃癌。