阿扎霉素B提取纯化工艺的优化

目的：建立阿扎霉素B的分离与纯化工艺。方法：将阿扎霉素B的发酵液进行加热处理后,采用乙醇-乙酸乙酯的浸提系统,进行结晶、重结晶和柱层析制备。结果：发酵液经600℃热处理30min后,于室温条件下放置1d,阿扎霉素B的损失率仅为3．9％,阿扎霉素B经柱层析后,纯度达到98．1％,得率达到91．2％。结论：阿扎霉素B发酵液加热处理有利于过滤和离心,可延长发酵液在室温条件下的放置时间,提高阿扎霉素B的稳定性,乙醇-乙酸乙酯的浸提系统有利于提高阿扎霉素B的得率。     

中段尿在常温下保存时间对培养结果的影响研究

目的 探讨临床尿液标本不同放置时间对细菌培养结果的影响,明确尿液标本合理保存时间,加强对标本细菌培养前的保存时间控制.方法 随机选取114份患者尿液标本,比较其在新鲜尿液即刻培养结果和室温(22 ～25℃)的环境中各放置0.5、1、2、3、4和5h等不同时间点细菌培养结果的分离率差异,采用样本率与总体率(新鲜尿液培养的分离率)的差别检验(|u|和P)分析其是否具有统计学意义.结果 新鲜尿液即刻培养与放置0.5h培养结果分离率差异无统计学意义(38.6％);之后随放置时间延长分离率逐渐升高,2h接种标本分离率为43％,差异无统计意义(|u| =0.9489,P ＞0.05);放置3、4和5h后接种标本分离率分别为50.9％、55.3％和63.2％,呈显著增高(|u|值分别为2.627、3.586和5.446,P值均小于0.01).结论 在常温下不同的保存时间对培养结果有着重要影响,尤其在2h后影响更为显著.准确有价值的培养结果,与标本合理的存放时间有极大的关系,加强尿液培养前阶段的保存时间控制非常重要.     

不同载体上微量接触类检材的相关问题探究

手部接触类生物物证是目前案件中的主要生物物证,但关于此类物证在不同载体上DNA的检出量和检验效果、最佳前处理方法以及检材放置不同时间后的检出量和检验效果的变化尚无详细研究报道。通过制备手部接触类生物检材,分别使用直接剪取法、胶带粘取法、两步擦拭法和真空吸取法对检材进行前处理,然后进行DNA提取,用筛选出的最佳前处理方法处理放置不同时间段的检材,均使用常规程序对检材进行DNA提取、定量和复合扩增,并对各项结果进行分析和讨论。实验观察到总体上使用直接剪取法进行前处理的检材提取到的DNA的量大于使用两步擦拭法和真空吸取法进行前处理提取到的DNA的量,且这4种前处理方法在不同载体的检材之间提取到的DNA量有差异;随着时间的推移,在放置360 d内的DNA检出量和检验效果无较大差异。由此得出,不同载体上DNA的检出量和检验效果有差异,针对不同载体,其最佳前处理方法也不同;检材常温干燥放置一年内,其DNA无明显降解。     

神经外科患者术后颅内感染的相关危险因素及护理对策

目的分析神经外科患者术后感染的相关危险因素,探讨相应护理对策。方法将2015年1月~2017年1月在我院神经外科住院行手术治疗的患者84例,依据术后有无感染进行分组,其中感染组42例,未感染组42例,并对两组患者的性别、年龄、手术时间、术中出血量、术后是否放置引流管及放置时间以及术后患者的意识进行统计分析。结果两组患者的性别比较差异无统计学意义(P0.05),但感染组患者的年龄大于未感染组(P0.05)。术后感染组的病因构成与术后未感染组的病因构成比较差异有统计学意义(P0.05),而且术前有无合并症比较亦有统计学意义(P0.05)。两组患者在手术时间、术中有无使用显微镜及术中出血量比较,差异均有统计学意义(P0.05)。两组患者术后放置引流管的时间、引流量及3天内昏迷例数比较,差异均有统计学意义(P0.05)。结论年龄大、手术时间长、术中出血多、术后放置引流管及术后3天昏迷的患者较易出现感染;神经外科术后出现颅内感染与多种因素相关,针对危险因素实施护理可减少术后感染的发生率。     

夏黑葡萄藤放置过程中化学成分的变化及可能变化机制分析

为分析夏黑葡萄藤在放置过程中化合物的种类、含量变化规律及机制。本研究应用超高效液相色谱仪联用四级杆串联飞行时间质谱仪(UPLC-Q-TOF-MS)在负离子模式下对夏黑葡萄藤中主要化学成分进行定性分析;采用高效液相色谱仪(HPLC)分析夏黑葡萄藤在放置过程中化合物的含量变化趋势。通过液质联用分析方法初步鉴定出夏黑葡萄藤中的黄酮类化合物主要有儿茶素、表儿茶素、槲皮素、槲皮素-3-O-半乳糖苷、petunidin 3-O-glucoside、trans-scirpusin A;芪类化合物为反式白藜芦醇、ε-葡萄素、vitisin B、miyabenol C;苯丙素类化合物为反式咖啡酸。葡萄藤在剪枝后放置过程中,反式白藜芦醇与ε-葡萄素在0～20天左右期间,含量呈显著上升趋势,最高值分别为新鲜样品中的250倍和190倍,从第20天起含量开始降低; vitisin B与miyabenol C为剪枝后放置过程中产生的新化合物,从第10天时含量开始上升,到第50天时含量开始下降。儿茶素、表儿茶素、槲皮素与反式咖啡酸的含量会随着葡萄藤放置时间的延长而持续降低。采用UPLC-Q-TOF-MS可以对葡萄藤中化合物进行快速分析鉴定;葡萄藤在放置过程中逆境胁迫会诱导芪类化合物(反式白藜芦醇、ε-葡萄素、vitisin B、miyabenol C)含量上升,而芪类化合物合成前体物质(trans-scirpusin A)和白藜芦醇合成的竞争物质(儿茶素、表儿茶素、槲皮素)含量则呈下降趋势。     

不同样本中甲螨的分离方法

采用电热分离法、清水漂浮法和振动分离法对不同样本中甲螨的分离时间、数量,样本的放置时间及电热分离所用热光源作了比较,结果证明,分离土壤甲螨时,土壤放置7d与立即分离所获甲螨数无差别,少量土样宜用清水漂浮法,大量土样宜用电热分离法,而植被样本宜用振动分离法。     

黄蜀葵花中β-半乳糖苷酶活性和金丝桃苷含量变化及其影响因素分析

对黄蜀葵[ Abelmoschus manihot( L.) Medikus]花不同部位的β-半乳糖苷酶(β-gal)活性和金丝桃苷含量进行了比较,并研究了开放程度、采收时间及采收后放置时间对花冠中β-gal活性和金丝桃苷含量的影响.结果显示:黄蜀葵花冠中β-gal活性和金丝桃苷含量分别为2.907 U和1.092％,均显著高于花萼和子房,分别为后两者的1.72倍和1.52倍,4.94倍和21.84倍.开放程度、采收时间及采收后放置时间对黄蜀葵花冠中β-gal活性和金丝桃苷含量有显著影响.总体上,完全开放和半开放的花冠中β-gal活性和金丝桃苷含量显著高于未开放及凋谢的花冠;随采收时间的推移(9:00至17:00)以及采收后放置时间的延长(0～5 h),花冠中β-gal活性逐渐升高、金丝桃苷含量逐渐降低;上午9:00采收的花冠中以及采收后0h的花冠中β-gal活性均最低、金丝桃苷含量均最高.研究结果表明:为使黄蜀葵花中金丝桃苷含量维持较高的水平,应于上午9:00左右采收完全开放的花冠,采收后应及时进行相应的处理.     

诱饵诱集时间与红火蚁工蚁诱集量的关系研究

为了明确诱饵诱集时间与红火蚁工蚁诱集量之间的关系,确定最佳的诱饵放置时间,本研究采用火腿肠诱饵诱集法,观察不同季节、不同时间段红火蚁诱集的个体数量,利用房室模型分析诱饵诱集时间与红火蚁工蚁诱集量之间的关系。结果表明,随着诱饵放置时间的增加,红火蚁工蚁的诱集数量会出现一个高峰,春季诱集高峰出现在诱饵放置后38-44 min,秋季出现在诱饵放置后24-29 min,并建立了不同季节、不同时间段红火蚁诱集量与时间的关系模型,分别为Y=12764.8807×e(-0.029102 X)"12820.4625×e(-0.030064 X)(春季上午)、Y=16166.6800×e(-0.023994 X)"16217.0808×e(-0.024866 X)(春季下午)、Y=12211.9095×e(-0.040576 X)"12275.2496×e(-0.041620 X)(秋季上午)、Y=12306.4111×e(-0.049724 X)"12383.6907×e(-0.051217 X)(秋季下午)。因此,在利用火腿肠诱饵监测红火蚁时,春季诱饵放置的最适时间约为40 min,秋季的最适时间约为30 min。     

Ⅲ价轮状病毒基因重配疫苗稳定性研究

为了研究Ⅲ价轮状病毒基因重配疫苗的稳定性,对2~8℃、25℃、37℃放置不同时间的9批成品疫苗定期取样观察外观物理性状、检测病毒滴度。结果表明,在2~8℃可保存两年以上,疫苗滴度保持不变;在25℃放置2周、37℃放置1周后疫苗滴度开始下降,因此,该疫苗在贮存、运输以及使用过程中环境温度应以2~8℃为宜。     

CHO—C28细胞收集液中乙型肝炎病毒表面抗原收率的研究

用CHO-C28细胞表达乙型肝炎病毒表面抗原(HBsAg)生产基因工程乙肝疫苗,其产量受到CHO-C28细胞表达外源基因量的影响.本文通过CHO-C28细胞连续培养过程中表达(HBsAg)的参数、纯化过程中硫酸铵(A·S)饱和度、细胞收集液放置时间三个因素对RPHA滴度影响的研究结果表明细胞收集液以45%饱和度的A·S沉淀HBsAg能获得较高的HBsAg收率,细胞收集液4℃放置时间不宜超过15 d,RPHA滴度在132～1128之间的细胞收集液均可进入纯化流程进行纯化.     

Effect of Osmotic Shock and Low Salt Concentration on Survival and Density of Bacteriophages T4B and T4Bo1

Measurements of survival and buoyant densities of bacteriophages T4B, T4Bo(1), and T4D have demonstrated the following: (a) After suspension in a concentrated salt solution, T4B and T4D are sensitive both to osmotic shock and to subsequent exposure to low monovalent salt concentrations. (b) Sensitivity of T4B to dilution from a concentrated salt solution is dependent on dilution rate, that of T4D is less dependent, and that of T4Bo(1) is independent. (c) Sensitivity of all three phages to low salt concentrations depends on initial salt concentrations to a variable extent. (d) Density gradient profiles indicate that nearly half of osmotically shocked T4B retain their DNA. Similar analysis demonstrates that few, if any, T4Bo(1) lose DNA when subjected to a treatment causing 90% loss of infectivity. (e) The effective buoyant densities of T4B and T4Bo(1) depend significantly on the dilution treatments to which the phages are subjected prior to centrifugation in CsCl gradients. These data are explicable in terms of the different relative permeabilities of the phages to water and solutes, and of alterations in the counterion distribution surrounding the DNA within the phage heads.     

盐胁迫下不同基因型冬小麦渗透及离子的毒害效应

以4种不同基因型冬小麦为试验材料,利用分根法研究了盐胁迫对小麦的渗透胁迫和离子毒害的效应。结果表明,在盐胁迫下,小麦既受渗透胁迫,也受盐离子胁迫。渗透胁迫效应比较快,大约在处理后1-2d内发生;离子毒害效应比较缓慢,大约需3-4d时间。在一半盐胁迫(200mmol/L NaCl)和一半非盐胁迫的分根条件下,小麦没有明显的渗透胁迫效应,小麦植株地上部Na⁺ 累积到毒性水平之前盐处理对小麦生长无抑制效应。小麦具有将Na⁺ 从盐胁迫一侧转移非盐一侧的能力,说明小麦吸收的Na⁺ 有一部分可以从地上部回流到根系中,回流率可达76%-89%。无水分胁迫(不加入PEG)的回流率大于水分胁迫(加入PEG)的回流率。不同基因型小麦在盐分吸收累积和回流,及渗透和离子胁迫的速度和程度等方面具有明显差异。NR 9405和小偃6号的Na⁺ 累积速度要少于陕229和RB 6;NR 9405根系排Na⁺ 能力强于陕229和RB 6。因此,NR 9405和小偃6号的耐盐性高于陕229和RB 6。     

DNA-induced secondary structure of the carboxyl-terminal domain of histone H1

We have studied the secondary structure of the carboxyl-terminal domains of linker histone H1 subtypes H1(0) (C-H1(0)) and H1t (C-H1t), free in solution and bound to DNA, by IR spectroscopy. The carboxyl-terminal domain has little structure in aqueous solution but becomes extensively folded upon interaction with DNA. The secondary structure elements present in the bound carboxyl-terminal domain include the alpha-helix, beta-structure, turns, and open loops. The structure of the bound domain shows a significant dependence on salt concentration. In low salt (10 mm NaCl), there is a residual amount of random coil, 7% in C-H1(0) and 12% in C-H1t. In physiological salt concentrations (140 mm NaCl), the carboxyl termini become fully structured. Under these conditions, C-H1(0) contained 24% alpha-helix, 25% beta-structure, 17% open loops, and 33% turns. The latter component could include a substantial proportion of the 3(10) helix. Despite their low sequence identity (approximately 30%), the representation of the different structural motifs in C-H1t was similar to that in C-H1(0). Examination of the changes in the amide I components in the 20-80 degrees C temperature interval showed that the secondary structure of the DNA-bound C-H1t is for the most part extremely stable. The H1 carboxyl-terminal domain appears to belong to the so-called disordered proteins, undergoing coupled binding and folding.     

Physico-chemical studies of taste reception. IV. Response of individual phospholipid membrane to a variety of chemical stimuli.

Variations in the membrane potential across model membranes made of Millipore filter paper and various single phospholipids were measured in response to salt, acid and distilled water. The phospholipids used were phosphatidylcholine (c), spingomyelin (SM), phosphatidylethanolamine (PE), and phosphatidylserine (PS). Results were compared with those obtained with the model membrane made of the total lipids extracted from bovine tongue epithelium, which simulated well the receptor potential observed with intact tast organs. The membrane potential of PE- and PS-membranes increased monotonously with increase of the concentration of 1:1 type salt, while that of PC- and SM-membranes exhibited no appreciable change in 1:1 salt solutions. Application of CaC12 to the membranes brought about a varity of response depending on the species of lipids used. PE- and PS-membranes showed a larger change in the membrane potential than PC- and SM-membranes when pH of the solution was varied. Fe-3+ was strongly absorbed on the surface of PC and SM-membranes, while Fe-3+ bound to PE- and PS-membranes was easily removed by an application of salt solution. A transient increase in the membrane potential was observed when distilled water was applied to the membrane adapted to an appropriate salt solution, which was similar to the water response observed in taste cells. PC- and SM-membranes responded to water when the membrane adapted to either NaC1 or CaC12, but PS-membrane responded only when the membrane was adapted to a solution containing CaC12. PE-membrane did not respond to water in any cases examined. The membrane prepared with a mixture of two species of phospholipids responded neither to salt nor to water, while the membranes prepared with the total lipids or a mixture of three species of lipids in appropriate ratio responded to both. The water response of the total lipids membrane vanished in a high temperature medium, while the water response of PC-membrane retained in all temperature ranges examined, i.e. between 20 degrees and 62 degrees C. The results obtained suggest that a mosaic structure, where each domain has different functions against various chemical stimuli, is formed on the surface of the model membrane made of the total lipids.     

The length of a junction between the B and Z conformations in DNA is three base pairs or less

Recently it has been suggested that double-helical complexes formed between the DNA sequences (CG)n(A)m and their conjugates, (T)m(CG)n, would be candidates for the formation of a B-Z junction in aqueous solution at high salt concentrations [Peticolas et al. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 2579-2583]. The junction was predicted to occur between a B-type helix in the d(A)m.d(T)m section and a Z-type helix in the self-complementary (CG)n.(CG)n sequence. In this paper we report Raman experiments on the deoxyoligonucleotides d(CGCGCGCGCGCGAAAAA) and d(CGCGCGAAAAA) and their complements. It is found the latter compound cannot be induced into the Z form in saturated salt solution but that the former sequence goes into a B-Z junction at 5.5 M salt. From a comparison of the relative intensity of the Raman conformational marker bands for B and Z DNA for both the A-T and C-G base pairs, it is shown that in 5.5 M NaCl solution none of the A-T base pairs are in the Z form, but nine of the C-G base pairs are in the Z form. The remaining three C-G base pairs are either in the junction or in the B form. Thus, the junction is formed from three or less C-G base pairs. If the solution is made 95 microM with NiCl2, then the entire duplex goes into the Z form and the Raman bands of the adenine are completely changed into those of the Z form.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hairpin and duplex formation in DNA fragments CCAATTTTGG, CCAATTTTTTGG, and CCATTTTTGG: a proton NMR study

Three DNA fragments, CCAATTTTGG (1), CCAATTTTTTGG (2), and CCATTTTTGG (3), were studied by proton NMR spectroscopy in aqueous solution. All these oligodeoxyribonucleotides contain common sequences at the 5' and 3' ends (5'-CCA and TGG-3'). 2 as well as 3 forms only hairpin structures with four unpaired thymidylyl units, four and three base pair stems, respectively, in neutral solution under low and high NaCl concentrations. At high salt concentration the oligomer 1 forms a duplex structure with -TT- internal loop. On the other hand, the same oligomer forms a stable hairpin structure at low salt and low strand concentrations at pH 7. The hairpin structure of 1 has a stem containing only three base pairs (CCA.TGG) and a loop containing four nucleotides (-ATTT-) that includes a dissociated A.T base pair. The two secondary structures of 1 coexist in an aqueous solution containing 0.1 M NaCl, at pH 7. The equilibrium shifts to the hairpin side when the temperature is raised. The stabilities and base-stacking modes of all three oligonucleotides in two different structures are reported.     

B--Z conformational transition in d(CGCGCGTTAATT), d(CGCGCGTTAA) and d(CGCGCGTT)

Conformational studies on three DNA-oligomers (d(CGCGCGTTAATT), d(CGCGTTAA) and d(CGCGCGTT) in solution by circular dichroism spectroscopy are reported. In low salt solution, all three DNA oligomers exhibit a characteristic B-conformation. However, under the influence of high salt concentration i.e. 5M NaCl, the octamer d(CGCGCGTT) exhibits 'A' conformation whereas the decamer and dodecamer retain B-conformation. On addition of millimolar amount of NiCl2 to the 5M NaCl, solution of oligodeoxynucleotides a B-Z transition is observed in octamer, decamer and dodecamer. However, NiCl2 titrations show that mid point of transition for dodecamer is at 2.25 mM, for decamer is at 13 mM NiCl2 and for octamer is 17 mM at NiCl2. In 60% alcohol all three oligonucleotides remain in the B-conformation. The melting temperatures of oligonucleotides at various salt concentration are also reported. Thermodynamic parameters calculated by melting profile using a two state model show that dodecamer and decamer are most stable in their 5M NaCl, B-form. However, octamer is more stable in its Z form than that of its 'A' form.     

Salt-dependent folding of long duplex DNA by histone H1.

It is found that T4 phage DNA complexed with histone H1 assembled into a string-of-bead structure, when the complex is prepared by a gentle diluting procedure from a high salt solution (2 M NaCl) to a low salt solution (50 mM NaCl). We used fluorescence microscopy to perform the real-time observation on formation and motion of a string-of-bead structure. Spatial histone H1 distribution on the DNA-H1 complex is observed by immuno-fluorescence microscopy.     

Irreversible thermodynamic analysis of electrophoretic light scattering experiments

A fluctuation theory for electrolyte solutions is developed based on the coupling between the equations of nonequilibrium thermodynamics and the Poisson equation. The resulting fluctuation theory is applied to the analysis of electrophoretic light scattering. It is shown that in a binary electrolyte solution (two ionic species), the Doppler shift is not determined by the electrical mobility of either ion, but depends instead on the rate of change of transference number with salt concentration. In addition the ionic relaxation time is shown to be proportional to the conductivity of the solution.     

Possible Modes of Salt Secretion in Avicennia marina in the Sinai

Avicennia marina salt glands were studied by scanning electronmicroscopy (SEM), in order to relate their ultrastructure tothe extracellular salt secretion process. It was found thata multiphase asynchronous process regulates the salt secretion.In the light of the present study and previous evidence we describetwo mechanisms of salt secretion. The first mechanism is a merocrineone, consisting of the formation of a vesicle that expands untilit reaches a maximal size, when it bursts, releasing the saltsolution. Later the burst vesicle disintegrates and a new onebegins to form. The second suggested mechanism is an holocrineone and begins with the accumulation of the secreted solutionin the subcuticular space. This results in the tearing of thecuticle and the release of the salt solution as droplets. Thefirst suggested mode of secretion operates regularly, whilethe second one takes place only occasionally. (Received February 28, 1989; Accepted October 17, 1989)