一种检测新型生物高分子材科聚γ-谷氨酸的新方法

通过聚γ-谷氨酸(γ-PGA)与氯化十六烷基吡啶(CPC)的乙酸钠水溶液反应形成混悬液,采用分光度计于波长680nm处比浊,研究γ-PGA浓度与吸收度之问的线性关系,并研究本方法测定γ-PGA的稳定性、重现性和回收率.在一定pH值和离子强度下,γ-PGA在12.5～50μg/ml范围内与CPC的乙酸钠水溶液生成的混悬液在波长680nm处的吸收度与其浓度呈线性关系,R2=0.9939.本方法在2h内吸收度保持稳定(RSD=O.154%,n=10),CPC法测定浓度为5,10和40μg/ml时的平均回收率分别为86%,77%和99.75%,RSD分别为0.14%,0.23%和0.025%应用比浊法测定γ-PGA的含量方便、简洁、重现性好,可用于γ-PGA浓度的检测.     

纳豆芽孢杆菌(Bacillus subtilis natto)固体发酵生产γ-PGA

γ-多聚谷氨酸是一种生物可降解的高分子材料 ,可应用于许多领域 ,因此受到普遍的重视。目前γ-PGA液体发酵水平为 5 0～ 60g/ L。报告了用大豆固体发酵生产γ-PGA的方法 ,其中包括 :菌种的筛选 ,发酵和提纯方法 ,高压液相法测定含量和SDS-聚丙烯酰胺凝胶电泳鉴定。结果 :BacillussubtilisnattoHW_1发酵活性为 1 1 5g/ kg大豆。γ_PGA的纯度为 95 %以上 ,分子质量为31 6kDa。另外可在大豆固体发酵生产纳豆激酶的同时生产回收γ-PGA ,既可以降低产品成本 ,又可以开发应用γ-PGA。     

赖氨葡锌颗粒中盐酸赖氨酸含量测定方法改进

目的:建立HPLC法测定赖氨葡锌颗粒中盐酸赖氨酸含量。方法:色谱柱为μBondpark C18柱,以甲醇:0.05mol/L醋酸钠和醋酸溶液(65:35)作为流动相,流速为1.0ml.min-1,检测波长为360nm。结果:盐酸赖氨酸在2.4~24.6μg/ml的浓度范围内呈良好的线性关系,平均回收率为99.28%,RSD=1.0%(n=6)。结论:建立的方法简便、快速、重现性好、结果准确,可用于赖氨酸的含量测定。     

HPLC法测定南瓜中β-胡萝卜素

目的：建立高效液相色谱法（HPLC）测定南瓜中β-胡萝卜素含量的方法,并对12份南瓜样品中β-胡萝卜素含量进行测定。方法：色谱柱：Eclipse XDB-C18柱（4.6mm×250mm,5μm）;流动相：水（A）+丙酮（B）;检测波长：450nm。结果：南瓜中β-胡萝卜素在35 min内得到较好分离,重复性好（RSD=5.11%）,精密度高（RSD=0.70%）,稳定性好（RSD=2.73%）,加标回收结果准确可靠（RSD=2.06%）。12份南瓜样品中β-胡萝卜素含量差异较大（8.9～94.4 μg/g）,印度南瓜16296-1中β-胡萝卜素含量最高,其次为中国南瓜9132、印度南瓜16291-2和16167-8,这3种南瓜中β-胡萝卜素含量较接近（均≥76 μg/g）,含量最低的为印度南瓜16185-6。结论：建立了一种快速测定南瓜中β-胡萝卜素的高效液相色谱方法,该方法准确、可靠;12份南瓜样品中β-胡萝卜素含量差异较大。     

胃灵合剂中黄芩苷的含量测定

目的:对胃灵合剂中黄芩苷的含量运用高效液相色谱(HPLC)法测定分析。方法:采用VP-ODS C18色谱硅胶分析柱为固定相,甲醇-0.3%的磷酸水溶液为流动相,流速为1 ml.min-1,紫外检测波长为280nm。结果:黄芩苷峰与其他杂质峰分离良好,0.3511μg~1.2872μg范围内,线性关系良好R=0.9999。平均回收率为99.04%,RSD=0.54%(n=9)。结论:该方法简便易行,可靠准确,专属性强,重现性好,可用于胃灵合剂的质量控制。     

瑞舒伐他汀钙胶囊溶出度测定的方法学研究

目的:验证瑞舒伐他汀钙胶囊溶出度的测定方法。方法:采用浆法,以水900ml为溶出介质,转速50转/分,用紫外分光光光度计在242nm波长处测定样品的吸光度。结果:瑞舒伐他汀钙在2.16~21.6ug/ml的浓度范围内与吸光度成良好的线性关系,r=1(n=6),低中高3种浓度的平均回收率为在98.89%,RSD为0.63%。结论:本法能快速准确的测定瑞舒伐他汀钙胶囊的溶出度。     

高效液相色谱法测定浓缩苹果汁中棒曲霉素

建立了高效液相色谱法 (HPLC)测定浓缩苹果汁中棒曲霉素含量的方法。用乙酸乙酯提取浓缩苹果汁中棒曲霉素 ,碳酸钠水溶液净化提取液 ,蒸干乙酸乙酯层 ,其残留物用醋酸缓冲液溶解。棒曲霉素的含量测定采用HypersilODS (5 μm ,2 5 0mm×4 6mmi d)色谱柱 ,流动相V(乙腈 ) :V(醋酸盐缓冲液 ) :V(水 ) =5 :3:2 ,流速 1ml min ,检测波长 2 76nm。结果表明 :棒曲霉素浓度与峰面积有很好的线性关系 ;用HPLC测定浓缩苹果汁中棒曲霉素的含量可操作性强、准确度高 ,棒曲霉素回收率高达 99 2 %,重现性好 (RSD为 0 4 %) ;灵敏度高最小检出量为 10 μg L。     

以沙苑子苷为对照品测定沙苑子总黄酮含量

目的 :以沙苑子苷为对照品测定沙苑子总黄酮含量。方法 :80 %乙醇提取液 ,2 6 6nm测定紫外吸收度。结果 :总黄酮含量为 2 1.5mg/g ,RSD =1.0 0 % ;回收率 95 .4 % ,RSD =2 .2 7% ,线性范围 4～ 2 4ug/ml。结论 :本法测定沙苑子总黄酮含量 ,操作简便 ,稳定性好 ,可用于沙苑子的质量控制。     

分光光度法测水红花子中花旗松素含量

目的:检测水红花子中花旗松素的含量.方法:采用紫外分光先度法,在常温下(25℃)290nm处,对水红花子乙醇提取物进行吸光度测定.结果:此方法线性范围:0.002～0.01 g/L,花旗松素浓度与吸光度线性关系:y=0.0724x 0.007,r2=0.9986;平均回收率为99.37%,RSD=0.897%.结论:紫外分光光度法测定水红花子中花旗花素合量操作简便、快速和准确度高,具有一定实用价值.     

硫酸铜络合法测定枸橼酸钾含量

目的:确定测定枸橼酸钾缓释片中枸橼酸钾含量的方法.方法:利用枸橼酸盐与Cu2+的络合物在紫外区有特定吸收,测定枸橼酸钾缓释片中枸橼酸钾的含量.结果:枸橼酸钾与硫酸铜形成络合物时最大摩尔比为1:1,枸橼酸钾浓度在10.78～53.9 ug/ml范围内,测定波长为(240±2)nm,吸收度与浓度呈良好线性关系,平均回收率为98.1%,RSD=1.85%(n=9).结论:方法、简单、准确,可作为枸橼酸钾缓释片中枸橼酸钾含量测定方法.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.