Formation Mechanism of the Free Radical Product and Its Precursor by the Reaction of Dehydro-L-ascorbic Acid with Amino Acid

During the formation of radical A (2) and its precursor (tris(2-deoxy-2-L-ascorbyl)amine, 1) by the reaction of dehydroascorbic acid (DHA) with amino acid, ascorbic acid (AsA) and the reduced red pigment (3) were newly identified, in addition to scorbamic acid (SCA) and the red pigment (4), as intermediate products. The addition of AsA to the DHA-amino acid reaction, as well as to the DHA-SCA reaction, greatly increased the formation of 3 and 1. The reaction of AsA with 4 gave rapidly 3, followed by the gradual production of 1. From these results, a reaction pathway is proposed that 3 formed by the reduction of 4 with AsA is a key intermediate and its condensation with DHA followed by reduction with AsA might produce 2 and 1.     

血清IL-6、IL-8、IgM抗体及T细胞亚群水平对新生儿先天性梅毒的诊断价值

目的:探讨血清白介素-6(IL-6)、白介素-8(IL-8)、IgM抗体及T细胞亚群对先天性梅毒新生儿的诊断价值。方法:选择2015年5月至2017年5月在我院进行临床治疗的先天性梅毒新生儿81例为观察组,另选同期来我院进行健康体检81例新生儿为对照组。比较两组患者血清IL-6、IL-8、T细胞亚群中CD~(3+)、CD~(4+)、CD~(8+)、CD~(4+)/CD~(8+)细胞及IgM抗体的阳性率。结果:治疗后,观察组血清IL-6、IL-8水平均明显高于对照组(P0.05),T细胞亚群中CD~(3+)、CD~(4+)、CD~(4+)/CD~(8+)明显低于对照组,而CD~(8+)T细胞比例高于对照组(P0.05)。19S-IgM-TP ELISA法检测出IgM的阳性率92.59%,明显高于TRUST法(74.07%)及TP-ELSA法(70.37%)(P0.05)。ROC曲线中,血清IL-8特异度为88.34%明显高于血清IL-6特异度81.48%、IgM抗体特异度60.13%、T细胞亚群特异度65.34%;IgM抗体的曲线面积88.91 cm~2明显大于IL-6的曲线面积45.09 cm~2、IL-8的曲线面积76.19 cm~2、T细胞亚群的曲线面积77.35 cm~2;T细胞亚群准备性67.89%明显高于IL-6准确性60.39%、IL-8准确性51.09%、IgM抗体准确性50.12;IgM抗体的灵敏度60.13%高于IL-6灵敏度59.19%、IL-8灵敏度42.35%、T细胞亚群灵敏度59.37%。具有比较意义(P0.05)。结论:血清IL-6、IL-8水平、T细胞亚群中CD~(3+)、CD~(4+)、CD~(8+)、CD~(4+)/CD~(8+)及IgM抗体阳性率是诊断先天性梅毒新生儿的重要指标。     

Conformationally Restricted 2-Substituted Wyosine Derivatives. 1H, 13C,and 15N NMR Study

Abstract

It was found by ¹H, ¹³C and ¹⁵N NMR study that substitution of 4,9-dihydro-4, 6-dimethyl-9-oxo-3-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl) imidazo [1,2-a]purine (wyosine triacetate, 1) at C2 position with electronegative groups CH₃O and C₆H₅CH₂O results in a noticeable electron distribution disturbance in the “left-hand” imidazole ring and a significant increase in the North conformer population of the sugar moiety.     

Patterns of soil and plant nitrogen isotope composition and their relationships with climate factors in Xilingol League,Inner Mongolia,China

Background: Plant and soil nitrogen stable isotope (δ¹⁵N) can integrate several fundamental biogeochemical processes in ecosystem nitrogen dynamics, and reflect characteristics of ecosystem nitrogen cycling.

Aims: We investigated how climate change influenced plant-soil nitrogen cycling by relating soil δ¹⁵N, plant δ¹⁵N and Δδ¹⁵N (difference between soil and plant δ¹⁵N) with climatic factors.

Methods: Field investigation was conducted in temperate grasslands in Inner Mongolia during August 2015. Plant δ¹⁵N, soil δ¹⁵N and Δδ¹⁵N were determined, and their relationships with climatic factors were examined by simple regression analyses and general linear models.

Results: Soil δ¹⁵N was significantly higher than plant δ¹⁵N, and there was a positive linear correlation between them. Soil and plant δ¹⁵N were negatively related with mean annual precipitation (MAP) and positively with mean annual temperature (MAT); conversely, Δδ¹⁵N was positively related with MAP and negatively with MAT.

Conclusion: Soil δ¹⁵N was dominantly controlled by MAT, while it was MAP for plant δ¹⁵N. Climate factors influenced plant δ¹⁵N not only through their effects on soil nitrogen dynamics but also strategies of plant nitrogen acquisition. Thus, compared with plant δ¹⁵N, soil δ¹⁵N can more accurately reflect soil nitrogen dynamics, while plant δ¹⁵N may integrate soil nitrogen dynamics and plant nitrogen acquisition.     

O6-Protection and Other Transformations at Guanosine and Inosine Lactam Sites with Application of Related Pyridinium Salts

Abstract

Nucleophilic displacement reactions of guanosine- and inosine-derived pyridinium salts will be discussed in a view of their preparative applications in nucleoside and oligonucleotide chemistry.     

Studies on the Later Stage of the Biosynthesis of Pleuromutilin

Mutilin (4) and deoxy analogues 2 and 3 are biosynthetic precursors of pleuromutilin (1) in the later stage of biosynthesis. Precursors 2 and 3 are required for studies on the oxygenation steps in biosynthesis, and were synthesized from readily available 1 via 4 by deoxygenation of the hydroxy groups. Feeding experiments with the ²H-labeled precursors confirmed their microbial conversion into 1.     

Structures and stability of N<Subscript>13</Subscript><Superscript>+</Superscript> and N<Subscript>13</Subscript><Superscript>−</Superscript> clusters

The structures and stabilities of eleven N₁₃ ⁺ and N₁₃ ^– isomers have been investigated with second-order Møller–Plesset (MP2) and density functional theory (DFT) methods. Five N₁₃ ⁺ isomers and six N₁₃ ^– isomers are all reasonable local minima on their potential energy hypersurfaces. The most stable N₁₃ ⁺ cation is structure C-2 with C_2v symmetry, which contains a pentazole ring and two N₄ open chains. It is different from those of the N₇ ⁺ and N₉ ⁺ clusters, but similar to the N₁₁ ⁺ cluster. Meanwhile, the most stable N₁₃ ^– structure A-2 is composed of a pentazole ring and a six-membered ring connected by two nitrogen atoms. It is not only different from those of the N₇ ^– and N₉ ^– clusters, but also from the N₁₁ ^– cluster. The decomposition pathways of structures C-2 and A-2 were investigated at the B3LYP/(aug)-cc-pVDZ level. From the barrier heights of the structures C-2 and A-2 decomposition processes, it is suggested that C-2 is difficult to observe experimentally and A-2 may be observed as a short-lived species. Figure Optimized geometrical parameters of N₁₃ ⁺ isomer C-2      

Complete 1H, 13C and 15N NMR assignments and secondary structure of the 269-residue serine protease PB92 from Bacillus alcalophilus

Summary The ¹H, ¹³C and ¹⁵N NMR resonances of serine protease PB92 have been assigned using 3D tripleresonance NMR techniques. With a molecular weight of 27 kDa (269 residues) this protein is one of the largest monomeric proteins assigned so far. The side-chain assignments were based mainly on 3D H(C)CH and 3D (H)CCH COSY and TOCSY experiments. The set of assignments encompasses all backbone carbonyl and CH_n carbons, all amide (NH and NH₂) nitrogens and 99.2% of the amide and CH_n protons. The secondary structure and general topology appear to be identical to those found in the crystal structure of serine protease PB92 [Van der Laan et al. (1992) Protein Eng., 5, 405–411], as judged by chemical shift deviations from random coil values, NH exchange data and analysis of NOEs between backbone NH groups.Abbreviations 2D/3D/4D two-/three-/four-dimensional - HSQC heteronuclear single-quantum coherence - HMQC heteronuclear multiple-quantum coherence - COSY correlation spectroscopy - TOCSY total correlation spectroscopy - NOE nuclear Overhauser enhancement (connectivity) - NOESY 2D NOE spectroscopy Experiment nomenclature (H(C)CH, etc.) follows the conventions used elsewhere [e.g. Ikura et al. (1990) Biochemistry, 29, 4659–4667].     

NMR Spectroscopic Study of a DNA Duplex with Mercury-Mediated T-T Base Pairs

Recently, we reported that T-T mismatches can specifically recognize Hg ^II (T-Hg ^II -T pair formation). In order to understand the properties of the T-Hg ^II -T pair, we recorded NMR spectra for a DNA duplex, d(CGCG TT GTCC) ? d(GGAC TT CGCG), with two successive T-T mismatches (Hg ^II -binding sites). We assigned ¹ H resonances for mercury-free and di-mercurated duplexes, and performed titration experiments with Hg ^II by using 1D ¹ H NMR spectra. Because of the above mentioned assignments, we could confirm the existence of mono-mercurated species, because individual components gave independent NMR signals in the titration spectra.     

Effects of geometric isomerism in dinuclear antitumor platinum complexes on their interactions with N-acetyl-L-methionine

In this study, the reactions of N-acetyl-L-methionine (AcMet) with [{trans-PtCl(NH₃)₂}₂-μ-H₂N(CH₂)₆NH₂](NO₃)₂ (BBR3005: 1,1/t,t 1) and its cis analog [{cis-PtCl(NH₃)₂}₂-μ-{H₂N(CH₂)₆NH₂}]Cl₂ (1,1/c,c 2) were analyzed to determine the rate and reaction profile of chloride substitution by methionine sulfur. The reactions were studied in PBS buffer at 37°C by a combination of multinuclear (¹⁹⁵Pt, {¹H-¹⁵N} HSQC) magnetic resonance (NMR) spectroscopy and electrospray ionization time of flight mass spectrometry (ESITOFMS). The diamine linker of the 1,1/t,t trans complex was released as a result of the trans influence of the coordinated sulfur atom, producing trans-[PtCl(AcMet)(NH₃)₂]⁺ (III) and trans-[Pt(AcMet)₂(NH₃)₂]²⁺ (IV). In contrast the cis geometry of the dinuclear compound maintained the diamine bridge intact and a number of novel dinuclear platinum compounds obtained by stepwise substitution of sulfur on both platinum centers were identified. These include (charges omitted for clarity): [{cis-PtCl(NH₃)₂}-μ-NH₂(CH₂)₆NH₂-{cis-Pt(AcMet)(NH₃)₂}] (V); [{cis-Pt(AcMet)(NH₃)₂}₂-μ-NH₂(CH₂)₆NH₂] (VI); [{cis-PtCl(NH₃)₂}-μ-NH₂(CH₂)₆NH₂-{PtCl(AcMet)NH₃] (VII); [{PtCl(AcMet)(NH₃)}₂-μ-NH₂(CH₂)₆NH₂] (VIII); [{trans-Pt(AcMet)₂(NH₃)}-μ-NH₂(CH₂)₆NH₂-{PtCl(AcMet)(NH₃)] (IX) and the fully substituted [{trans-Pt(AcMet)₂(NH₃)}₂-μ-{NH₂(CH₂)₆NH₂] (X). For both compounds the reactions with methionine were slower than those with glutathione (Inorg Chem 2003, 42:5498–5506). Further, the 1,1/c,c geometry resulted in slower reaction than the trans isomer, because of steric hindrance of the bridge, as observed previously in reactions with DNA and model nucleotides.     

Efficient Synthesis of [2-15N]Guanosine and 2′-Deoxy[2′-15N]Guanosine Derivatives Using N-(tert-Butyldimethylsilyl)[15N]Phthalimide as a 15N-Labeling Reagent

Nucleophilic aromatic substitution of 9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-6-chloro-2-fluoro-9 H-purine with N-(tert-butyldimethylsilyl)[ ¹⁵ N]phthalimide in the presence of a catalytic amount of CsF at room temperature in DMF efficiently afforded the 6-chloro-2-[ ¹⁵ N]phthalimidopurine derivative, which was subsequently converted to the [2-¹⁵N]guanosine derivative was also efficiently synthesized through a similar procedure.     

~(13)C-标记秸秆添加对DNA稳定性同位素探针试验结果的影响

【目的】稳定性同位素探针技术(stable isotope probing,SIP)是采用稳定性同位素示踪复杂环境中具有代谢活性微生物的有力工具。然而,在近期利用SIP技术的研究当中,我们发现~(13)C-标记物对试验本身有一定程度影响。例如研究土壤秸秆降解微生物,需将~(13)C-标记作物秸秆添加到土壤,利用微域培养实验和DNA-SIP技术解析主导降解微生物物种。但是~(13)C秸秆的添加以及不同土壤肥力水平是否会影响土壤微生物群落有待商榷。【方法】本研究采集江西鹰潭红壤试验站3种施肥处理(Control、NPK、OM)水稻土壤,分别添加自然丰度(12C)和~(13)C-标记的高丰度水稻秸秆,进行微域培养试验,研究两种秸秆添加下的响应物种以及不同丰度C对生物质气体的累积排放、细菌a-多样性以及群落结构的影响。【结果】研究发现,3种施肥土壤下,2种丰度秸秆处理间C累计排放无差异。但是,寡营养条件(Control)下,~(13)C-标记秸秆处理的细菌a-多样性高,12C秸秆处理群落异质性高,稳定性较差,无差异性物种;与~(12)C秸秆处理相比,富营养条件(NPK和OM)下,~(13)C-标记秸秆处理的细菌a-多样性和群落结构无差异,但存在差异物种,主要集中于变形菌门和稀有物种。【结论】本研究的结果表明~(13)C标记秸秆对微生物群落有一定影响,因此在后续的SIP试验中,高丰度秸秆虽可被用来作为标记底物,但需慎用。     

Synthesis and Antimicrobial Evaluation of Novel Pyrazolones and Pyrazolone Nucleosides

The synthesis of a novel series of 4-arylhydrazono-5-methyl-1,2-dihydropyrazol-3-ones 4a–h, and their N ²-alkyl and acyclo, glucopyranosyl, and ribofuranosyl derivatives is described. K₂CO₃ catalyzed alkylation of 4a–h with allyl bromide, propargyl bromide, 4-bromobutyl acetate, 2-acetoxyethoxymethyl bromide, and 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide proceeded selectively at the N ²-position of the pyrazolinone ring. Glycosylation of 4a with 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose under Vorbruggen glycosylation conditions gave the corresponding N ²-4-arylhydrazonopyrazolone ribofuranoside 9a in good yield. Conventional deprotection of the acetyl protected nucleosides furnished the corresponding 4-arylhydrazonopyrazolone nucleosides in good yields. Selected numbers of the newly synthesized compounds were screened for antimicrobial activity. Compounds 4b, 12a, and 14d showed moderate activities against Aspergillus flavus, Penicillium sp., and Escherichia coli.     

Nucleoside H-Phosphonates. IX. Possible Side-Reactions During Hydrogen Phosphonate Diester Formation

Abstract

Possible side-reactions during hydrogenphosphonate diester formation in the presence of various condensing reagents (e.g. arensulfonyl derivatives, chlorophosphates and acyl chlorides) have been investigated using ³¹P NMR spectroscopy.     

Cr3+和Cd2+对普通小球藻生长及抗氧化酶活性的影响

[目的] 为探究重金属对淡水绿藻生长的影响。[方法] 选取对水质检测具有明显指示作用的普通小球藻（Chlorella vulgaris）为实验材料,CdCl₂·2H₂O和CrCl₃·7H₂O提供重金属离子,探究不同浓度Cr³⁺和Cd²⁺在单一和复合胁迫下对藻细胞浓度、叶绿素a及相关抗氧化酶活性的影响。[结果] 随着Cr³⁺和Cd²⁺浓度不断增加,藻细胞浓度呈先增长后下降趋势;叶绿素a含量呈现先下降后升高再下降的现象,浓度为1 mg/L的单一和复合胁迫下有最大值,且毒性作用表现为Cr³⁺ < Cd²⁺ < Cr³⁺+Cd²⁺;与藻细胞膜相关的丙二醛（MDA）和过氧化氢（H₂O₂）含量随着重金属离子浓度的增大而增长;重金属离子浓度低于10 mg/L时对藻细胞内抗氧化酶系统中的超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）表现为促进作用,而大于10 mg/L时具有抑制作用。[结论] 结果表明在单一或复合重金属胁迫下,普通小球藻会充分调动与抗逆性相关的酶来维持自身的正常生长。     

Irgm 1参与动脉粥样硬化斑块的形成

目的:探讨免疫相关GTP酶1(Irgm 1)对小鼠血管动脉粥样硬化(AS)斑块形成的影响。方法:高脂饲料喂养野生型(WT)、ApoE~(-/-)Irgm 1~(+/+)和ApoE~(-/-)Irgm1~(+/-)小鼠3个月,建立AS模型;取小鼠主动脉弓,免疫荧光染色方法观察WT和ApoE~(-/-)Irgm 1~(+/+)小鼠血管AS斑块中Irgm 1的表达情况及部位;Western blot方法检测WT和ApoE~(-/-)Irgm 1~(+/+)小鼠血管AS斑块中Irgm 1蛋白表达情况;Q-PCR方法检测WT和ApoE~(-/-)Irgm 1~(+/+)小鼠血管AS斑块中Irgm 1 m RNA表达情况;油红O染色观察ApoE~(-/-)Irgm1~(+/+)和ApoE~(-/-)Irgm1~(+/-)小鼠血管AS斑块形成情况;结果:与WT组相比,ApoE~(-/-)Irgm 1~(+/+)组小鼠主动脉弓AS斑块中Irgm 1+细胞明显增多,Irgm 1+细胞主要位于血管AS斑块的表面;与WT组相比,ApoE~(-/-)Irgm 1~(+/+)组小鼠血管AS斑块中Irgm 1蛋白表达显著增多(P0.001),Irgm 1 m RNA表达显著增多(P0.01);与ApoE~(-/-)Irgm1~(+/-)组相比,ApoE~(-/-)Irgm1~(+/+)组小鼠主动脉弓AS斑块面积显著增大(P0.01);结论:Irgm 1能够促进血管AS斑块的形成。     

放射性核素131I在甲亢治疗中的安全性与有效性

目的:探讨放射性核素~(131)I应用于甲亢治疗的安全性与有效性。方法:选择2013年8月到2016年2月选择在我院诊治的甲亢患者240例,根据随机信封抽签原则分为观察组与对照组各120例,对照组口服丙硫氧嘧啶片治疗,观察组在对照组治疗的基础上给予放射性核素~(131)I治疗,治疗观察3个月,记录治疗的安全性与有效性。结果:治疗后,观察组总有效率为96.7%,明显高于对照组的86.7%(P0.05)。观察组治疗后血清甲状腺激素水平明显低于治疗前及对照组(P0.05)。观察组治疗期间的甲减、粒细胞减少、肝脏损害、贫血等不良反应发生率为11.7%,对照组为10.8%,两组不良反应的发生率对比差异无统计学意义(P0.05)。结论:放射性核素~(131)I可使甲亢患者的甲状腺激素的分泌和合成显著减少,安全性及有效性均较高。     

基于Ti4+-IMAC富集的分枝菌酸小杆菌深度覆盖磷酸化蛋白质组研究

【目的】本研究以分枝菌酸小杆菌(Mycolicibacterium smegmatis)为研究对象,探索适于原核微生物理想的磷酸化富集方法。【方法】我们比较了二氧化钛(TiO₂)、Fe³⁺-NTA和Ti⁴⁺螯合在磷酸酯修饰的固相微球(Ti⁴⁺-IMAC) 3种不同富集方法磷酸化肽段的富集效率,并用不同分辨率的质谱仪评估富集稳定性。【结果】Ti⁴⁺-IMAC富集效率最高,磷酸化位点数是TiO₂或Fe³⁺-NTA方法的7倍以上;TiO₂和Fe³⁺-NTA方法富集到的磷酸化位点数相差不大,与已报道的用TiO₂方法富集的磷酸化位点数目接近。Ti⁴⁺-IMAC富集结果稳定性很好,高分辨率Lumos质谱仪鉴定到的磷酸化位点数是Velos的2.6倍。【结论】本研究较高效地实现了分枝菌酸小杆菌磷酸化事件的鉴定,共鉴定到2 280个磷酸化蛋白、10 880个磷酸化肽段及4 433个可信磷酸化位点,有望用于其他微生物的磷酸化蛋白质组学研究。     

Efficient Synthesis of 8-Thiosubstituted Guanine Derivatives as Potential Tools for Biochemical and Biological Studies

Abstract

A method for the selective introduction of the N²-(dimethylamino)methylene group into 8-thio-9-(2-hydroxyethoxymethyl)guanine (1) has been developed. The effect of the N²-amidine protection on the S-alkylation of 1 was studied.     

2型糖尿病并发肺结核患者PCT、HMGB1、CD4+/CD8+比值与继发肺部感染的关系

摘要 目的：探讨2型糖尿病并发肺结核患者降钙素原（PCT）、高迁移率族蛋白1（HMGB1）、CD4⁺/CD8⁺比值与继发肺部感染的关系。方法：选择2019年1月至2022年6月四川大学华西医院呼吸与危重症医学科收治的97例2型糖尿病并发肺结核患者,根据入院治疗时是否继发肺部感染分为肺部感染组（53例）及非肺部感染组（44例）。检测两组血清PCT、HMGB1水平以及外周血CD4⁺/CD8⁺比值。单因素和多因素Logistic回归分析2型糖尿病并发肺结核患者继发肺部感染的因素。受试者工作特征（ROC）曲线分析PCT、HMGB1和CD4⁺/CD8⁺比值预测2型糖尿病并发肺结核患者继发肺部感染的价值。结果：肺部感染组血清PCT、HMGB1水平高于非肺部感染组（P＜0.05）,外周血CD4⁺/CD8⁺比值低于非肺部感染组（P＜0.05）。糖化血红蛋白及血清PCT、HMGB1水平升高是2型糖尿病并发肺结核患者继发肺部感染的危险因素（P＜0.05）,高CD4⁺/CD8⁺比值是保护因素（P＜0.05）。PCT、HMGB1、CD4⁺/CD8⁺比值预测2型糖尿病并发肺结核患者继发肺部感染的曲线下面积为0.719、0.761、0.738,联合PCT、HMGB1和CD4⁺/CD8⁺比值预测的曲线下面积为0.878,高于各指标单独预测。结论：2型糖尿病并发肺结核患者血清PCT、HMGB1水平增高,外周血CD4⁺/CD8⁺比值降低,均与继发肺部感染有关,PCT、HMGB1联合CD4⁺/CD8⁺比值可辅助预测2型糖尿病并发肺结核患者继发肺部感染的风险。