纳米金标记DNA的生物传感器

目的利用纳米金标记DNA以提高传感器的检测灵敏度,为建立方便、快速、准确地检测食品中李斯特菌的方法提供依据。方法利用自组装法,将5′端巯基修饰的单链DNA固定在金电极上,然后与纳米金标记的探针进行杂交。结果传感器与标记有胶体金的探针杂交频率减少了207 Hz,与未标记有胶体金探针杂交频率(减少了52 Hz)相比提高了3倍。结论采用纳米金标记的探针可提高传感器的检测灵敏度,在食品安全检测中具有重要意义。     

新型压电DNA石英传感器快速检测结核分枝杆菌

目的设计一种新型的压电DNA石英传感器用于检测结核分枝杆菌。方法将巯基修饰寡核苷酸探针以自组装方式固定于压电石英晶振的金电极表面,取适量培养基上的标准菌株或痰样,加DNAzol提取,离心得到DNA沉淀,加Btg I限制性内切酶切出其IS6110片段。根据杂交前后晶体振荡频率的变化判断是否存在结核分枝杆菌。该压电DNA石英传感器优点在于无需PCR扩增,扩大了该技术的适用范围。结果本文设计的传感器最佳修饰探针浓度为1.5μmol/L,热处理后加入封闭寡核苷酸有效避免DNA复性,放大响应信号。与PCR扩增结果对比,临床阳性样品与传感器探针杂交后能引起频率明显下降,阴性样品没有明显的频率响应,两者结果一致。结论该传感器能有效区分结核分枝杆菌与其他临床常见病原微生物,具有良好的专属性。     

基于HRP-DAB信号放大系统的压电石英晶体DNA传感器微阵列检测表皮葡萄球菌的研究

目的在已构建的压电压电石英晶体DNA传感器检测系统中引入HRP-DAB生物信号放大系统,提高传感器的检测灵敏度,并基于该系统建立一种表皮葡萄球菌快速检测方法。方法采用自组装技术在压电石英晶体DNA传感器上固定针对表皮葡萄球菌的寡核苷酸探针,将掺入生物素(biotin)-dUTP的表皮葡萄球菌靶DNA与之进行杂交反应,加入HRP-链亲和素(streptavidin)、DAB工作液,观察反应频率变化;对35份表皮葡萄球菌感染的临床标本进行检测,并与传统培养法进行比较。结果该压电石英晶体DNA传感器微阵列检测表皮葡萄球菌的灵敏度为95.5%,特异度为84.6%,正确诊断指数为0.801,检出限为2×102CFU/ml,与血培养法差异无统计学意义(P>0.05)。结论基于HRP-DAB信号放大系统的压电石英晶体DNA传感器微阵列,有效的提高了压电石英晶体传感器检测的灵敏度,可用于临床病原菌感染的快速检测,具有较高的临床推广价值。     

利用自组装单分子层技术在传感器金膜表面构建DNA探针修饰电极的研究

目的在压电基因传感器阵列表面构建DNA探针修饰的金膜电极. 方法利用自组装单分子层(self-assembled monolayer, SAM)技术将5′端带有巯基的DNA探针共价交联到压电基因传感器的金膜表面,利用循环伏安计(circled voltammeter, CV),扫描隧道显微镜(scanning tunnel microscope, STM)分别观察探针交联前后金膜表面电化学表征及微观结构的改变. 结果 CV测量结果显示随着DNA探针在传感器金膜表面的吸附,界面电容减小;STM扫描结果更是直观地显示探针非常均匀、规整地在金膜电极表面形成一层SAM. 结论利用SAM技术可以很好地将DNA探针固定在压电基因传感器金膜表面.     

PNA与DNA探针对漏声表面波传感器特异性的影响

目的探讨以PNA作为杂交探针与普通的DNA探针相比,在漏声表面波生物传感器生物杂交反应中的优越性。方法用巯基固定法将PNA、DNA两种探针分别固定在漏声表面波生物传感器的金膜表面,分别与完全匹配、1个及2个碱基错配的靶序列进行杂交反应,观察两种不同的探针与靶序列反应所引起的相位变化及反应平衡时间。结果与DNA探针相比,PNA探针识别碱基错配的能力显著提高,且杂交平衡时间更短。结论 PNA探针可提高漏声表面波生物传感器的检测特异性。     

阳离子多聚体信号放大方法应用于压电基因生物传感器检测铜绿假单胞菌的研究

目的 探讨压电基因生物传感器引入阳离子多聚体（脂质体）信号放大方法，快速检测铜绿假单胞菌的可行性，建立一种新的利用静电吸附的压电信号放大方法。方法 在基因压电石英传感器阵列固定针对铜绿假单胞菌的寡核苷酸探针，加入靶DNA与之杂交反应，检测频率变化值，然后在杂交后的检测体系中加入不同浓度的脂质体，检测频率变化值，并与对照组进行比较。结果 加入阳离子多聚体后．频率变化值明显增大，与对照组相比较差异有统计学意义（P〈0．05），并且阳离子多聚体最适使用浓度为0．8μ／μ1。结论 阳离子多聚体可有效地放大压电传感信号。     

新型纳米金界面压电石英晶体DNA传感器的实验研究

目的构建一种新型纳米金界面压电石英晶体DNA传感器,探讨纳米金界面上进行寡核苷酸探针固定的最佳条件。方法构建纳米金颗粒修饰的石英晶振生物反应界面,进行巯基修饰的寡核苷酸探针的固定,对纳米金自组装pH值条件、探针固定浓度等影响因素进行实验研究;将构建的传感器和未经纳米金颗粒修饰的传感器用于铜绿假单胞菌检测,比较两种传感器的响应性能,并进一步对该纳米金界面压电石英晶体DNA传感器的再生进行研究。结果纳米金自组装的最佳pH值为6.0,探针最佳固定浓度为3.0μmol/L。纳米金颗粒修饰的石英晶振的响应性能大于未经修饰的石英晶振,可以重复使用5次。结论纳米金界面压电石英晶体DNA传感器,具有不需标记、操作简单、能实时在线检测、频率响应性能高、无污染和能重复使用等优点,在临床实验诊断方面应用前景广阔。     

乐甫波传感器表面核酸探针修饰电极的构建

目的在乐甫波(love wave)传感器表面构建DNA探针修饰电极。方法利用共价偶联方法将3’端带有氨基的DNA探针交联到乐甫波传感器的膜表面，通过网络分析仪(network analyzer)，原子力显微镜(atomic force microscopy，AFM)观察探针交联前后传感器传输参数及微观结构的改变。结果液相条件下，乐甫波器件的传输参数S21与瑞利波器件的参数相比仍保持明显的主瓣，而随着探针在乐甫波传感器表面的吸附，相位发生变化。探针较均匀、规整地在膜电极表面形成一层敏感膜。结论乐甫波传感器可以直接用于液相检测，用共价偶联技术可以很好地将DNA探针固定在乐甫波传感器膜表面，为以后的乐甫波生物传感器的实验研究打下基础。     

多聚T尾型探针在压电石英晶体微天平DNA传感器检测铜绿假单胞菌中的实验研究

目的 构建一种压电石英晶体微天平(QCM)DNA传感器多聚T尾型探针敏感膜制备新方法,同时对其重要影响因素进行优化探讨.方法 设计一种多聚T尾型探针,固定在压电QCM DNA传感器晶振表面,对探针固定浓度.杂交温度和杂交时间等因素进行实验研究,进一步将构建的多聚T尾型探针DNA传感器和普通探针DNA传感器用于铜绿假单胞菌检测,比较两种传感器的频率响应性能,同时对该压电QCM DNA传感器的再生性能进行研究.结果 探针最佳固定浓度为2.0 μmol/L,最适杂交温度为40℃,最适杂交时间为90 min;多聚T尾型探针DNA传感器的响应性能显著大于普通探针DNA传感器(P<0.05),可以重复使用7次.结论 基于多聚T尾型探针的压电QCM DNA传感器,具有杂交效率高、技术难度低、频率响应性能高等优点,在压电QCM DNA传感器基因检测领域有较好的应用前景.     

碳纳米管和纳米金自组装固定GOD的葡萄糖传感器的研究

目的：研制一种新型的葡萄糖传感器，用于临床检验患者的血糖浓度。方法：通过单层膜自组装技术将多壁碳纳米管、纳米金及葡萄糖氧化酶（GOD）固定到金电极上，用循环伏安法和线性扫描法考察传感器的组装特性、响应电流的性质、对葡萄糖浓度的响应特性。结果：对葡萄糖浓度进行定量分析，线性范围为10-1400mg／L．相关系数R^2=0．9909，检测限为0．0001mg／L。取3支电极测试4例不同浓度的标准样，结果RSD〈2％，在4℃干态保存30d后．响应电流仍然保持在80％，取106名糖尿病患者的临床血清进行检测，符合要求。结论：用多壁碳纳米管和纳米金固定葡萄糖氧化酶研制的葡萄糖传感器能用于临床检验。     

链置换扩增压电DNA传感器检测铜绿假单胞菌的临床应用研究

目的探讨链置换扩增(SDA)压电DNA传感器检测铜绿假单胞菌的临床应用.方法应用SDA压电DNA传感器芯片技术和特异性寡核苷酸探针,对临床标本33份进行铜绿假单胞菌检测,并以荧光定量PCR作参照,与常规培养进行对比分析.结果在33份临床标本中,SDA压电DNA传感器检出17份铜绿假单胞菌阳性,与荧光定量PCR结果完全一致,而这两种方法与常规分离培养略有差异.结论 SDA压电DNA传感器芯片技术能直接检测铜绿假单胞菌基因组DNA,具有准确、快速、灵敏的优点.     

压电免疫传感器两种抗体固定方法的比较研究

目的比较压电免疫传感器两种抗体固定方法的优劣,选择压电免疫传感器抗体敏感膜固定的最佳方法. 方法分别采用巯基化方法和蛋白A(SPA)固定法将抗人胰岛素单克隆抗体固定在压电免疫传感器金膜电极表面,比较不同抗体工作浓度、不同浓度标准溶液反应条件下抗体固定量、一致性以及传感器响应能力如频率变化、反应时间、检测线性范围以及反应非特异性等. 结果两种固定方法制备的压电免疫传感器其检测灵敏度、反应时间相当,但巯基化固定方法抗体固定量大、一致性好、检测线性范围较宽、非特异反应低. 结论抗体巯基化法制备的压电免疫传感器具有检测范围宽、非特异反应低等优点,是免疫传感器抗体敏感膜制备的理想方法.     

用于液相检测的压电免疫传感器研究

利用聚乙烯亚胺法，将Ｃ２型葡萄球菌肠毒素（ＳＥ）抗体固化在未抛光的压电晶体的金电极上，利用双调式振荡电路制作的振荡器，构建的压电免疫传感器其稳定性、特异性都较好     

Chemoprevention of hepatocarcinogenesis: S-adenosyl-L-methionine.

Accumulation of genetic changes characterizes the progression of cells, initiated by carcinogens, to full malignancy. Various epigenetic mechanisms, such as high polyamine synthesis, aberrant DNA methylation, and production of reactive oxygen species, may favor this process by stimulating growth and inducing DNA damage. We observed a decrease in S-adenosyl-L-methionine (SAM) content in the liver, associated with DNA hypomethylation in rat liver, during the development of preneoplastic foci, and in neoplastic nodules and hepatocellular carcinomas, induced in diethylnitrosamine-initiated rats by "resistant hepatocyte" (RH) protocol. Reconstitution of the methyl donor level in the liver by SAM administration inhibits growth and induces phenotypic reversion and apoptosis of preneoplastic cells. A 6-month SAM treatment results in a sharp and persistent decrease in development of neoplastic nodules, suggesting a long duration of SAM chemopreventive effect. Various observations support the suggestion of a role of DNA methylation in chemoprevention by SAM: (1) Exogenous SAM reconstitutes the SAM pool in preneoplastic and neoplastic liver lesions. (2) DNA methylation is positively correlated with SAM:S-adenosylhomocysteine (SAH) ratio in these lesions. (3) 5-Azacytidine, a DNA methyltransferase inhibitor, inhibits chemoprevention by SAM. (4) c-Ha-ras, c-Ki-ras, and c-myc are hypomethylated and overexpressed in preneoplastic liver. Their expression is inversely correlated with SAM:SAH ratio in SAM-treated rats. (5) S-Adenosyl-L-methionine treatment results in overall DNA methylation and partial methylation of these genes. Other possible mechanisms of SAM treatment include inhibition of polyamine synthesis, linked to partial transformation of SAM into 5'-methylthioadenosine (MTA), and antioxidant and antifibrogenic activities of both SAM and MTA.     

Intracellular S-adenosylhomocysteine concentrations predict global DNA hypomethylation in tissues of methyl-deficient cystathionine beta-synthase heterozygous mice.

Because S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are the substrate and product of essential methyltransferase reactions; the ratio of SAM:SAH is frequently used as an indicator of cellular methylation potential. However, it is not clear from the ratio whether substrate insufficiency, product inhibition or both are required to negatively affect cellular methylation capacity. A combined genetic and dietary approach was used to modulate intracellular concentrations of SAM and SAH. Wild-type (WT) or heterozygous cystathionine beta-synthase (CBS +/-) mice consumed a control or methyl-deficient diet for 24 wk. The independent and combined effect of genotype and diet on SAM, SAH and the SAM:SAH ratio were assessed in liver, kidney, brain and testes and were correlated with relative changes in tissue-specific global DNA methylation. The combined results from the different tissues indicated that a decrease in SAM alone was not sufficient to affect DNA methylation in this model, whereas an increase in SAH, either alone or associated with a decrease in SAM, was most consistently associated with DNA hypomethylation. A decrease in SAM:SAH ratio was predictive of reduced methylation capacity only when associated with an increase in SAH; a decrease in the SAM:SAH ratio due to SAM depletion alone was not sufficient to affect DNA methylation in this model. Plasma homocysteine levels were positively correlated with intracellular SAH levels in all tissues except kidney. These results support the possibility that plasma SAH concentrations may provide a sensitive biomarker for cellular methylation status.     

量子点高效偶联DNA用于铜绿假单胞菌检测

目的 建立量子点高效标记铜绿假单胞菌16s rDNA的方法,为实现铜绿假单胞菌的快速、准确检测奠定基础.方法 采用巯基法固定铜绿假单胞菌的16S rDNA P1探针于石英晶体金膜上,加入检测样本进行首次杂交,清洗后加入量子点标记的P2探针进行第2次杂交;最终通过荧光强度判断铜绿假单胞菌的浓度.结果 不同的DNA∶QD比例可以产生不同的QD-DNA复合体,该复合体的荧光强度对最终检测结果具有极大影响;随着DNA∶QD的比例增加,其偶联效率也随之增加,当DNA∶QD的比例为100∶1时,其偶联基本实现饱和,偶联效率不再升高.结论 该实验建立了一种新型的基于量子点检测铜绿假单胞菌16S rDNA的方法,为临床微生物的快速检测提供了一种新的技术方案.     

Impact of Integration of Severe Acute Malnutrition Treatment in Primary Health Care Provided by Community Health Workers in Rural Niger

The present study aimed to assess the effectiveness and impact on treatment coverage of integrating severe acute malnutrition (SAM) treatment at the health hut level by community health workers (CHWs). This study was a non-randomized controlled trial, including two rural communes in the health district of Mayahi: Maïreyreye (control) and Guidan Amoumoune (intervention). The control group received outpatient treatment for uncomplicated SAM from health facilities (HFs), while the intervention group received outpatient treatment for uncomplicated SAM from HFs or CHWs. A total of 2789 children aged 6–59 months with SAM without medical complications were included in the study. The proportion of cured children was 72.1% in the control group, and 77.2% in the intervention group. Treatment coverage decreased by 8.3% in the control area, while the group of CHWs was able to mitigate that drop and even increase coverage by 3%. This decentralized treatment model of acute malnutrition with CHWs allowed an increase in treatment coverage while maintaining a good quality of care. It also allowed the early inclusion of children in less severe conditions. These results may enhance the Niger Ministry of Health to review the management of SAM protocol and allow CHWs to treat acute malnutrition.     

压电免疫球蛋白微阵列免疫传感器抗体固定方法的研究

目的构建一种新型压电免疫球蛋白微阵列免疫传感器,探索SPA法在金电极表面进行抗体固定的最佳条件。方法以AT切型、基频10MHz的金膜石英晶体作为换能器,将抗人免疫球蛋白单克隆抗体固定在石英晶体电极表面,根据SPA能通过分子间作用力与Au原子形成稳定的SPA-Au复合物的原理,对抗体进行固定,对SPA固定抗体的最佳温度及时间条件、抗体浓度、pH值等影响因素进行实验研究。结果包被SPA宜于采用低温、长时间的包被方式,进行抗体固定的抗体溶液最佳浓度5mg/ml,pH值7.2。结论采用SPA法在石英晶体表面进行抗体固定操作简单、省时,是压电免疫传感器抗体固定的有效方法。     

Impact of Different Levels of Supervision on the Recovery of Severely Malnourished Children Treated by Community Health Workers in Mali

(1) Background: The Ministry of Health in Mali included the treatment of severe acute malnutrition (SAM) into the package of activities of the integrated community case management (iCCM). This paper evaluates the most effective model of supervision for treating SAM using community health workers (CHWs). Methods (2): This study was a prospective non-randomized community intervention trial with two intervention groups and one control group with different levels of supervision. It was conducted in three districts in rural areas of the Kayes Region. In the high supervision group, CHWs received supportive supervision for the iCCM package and nutrition-specific supervision. In the light supervision group, CHWs received supportive supervision based on the iCCM package. The control group had no specific supervision. (3) Results: A total of 6112 children aged 6–59 months with SAM without medical complications were included in the study. The proportion of cured children was 81.4% in those treated by CHWs in the high supervision group, 86.2% in the light supervision group, and 66.9% in the control group. Children treated by the CHWs who received some supervision had better outcomes than those treated by unsupervised CHWs (p < 0.001). There was no difference between areas with light and high supervision, although those with high supervision performed better in most of the tasks analyzed. (4) Conclusions: Public policies in low-income countries should be adapted, and their model of supervision of CHWs for SAM treatment in the community should be evaluated.