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961.
Sun Y Zhou H Zhang Q Wu X 《Artificial cells, blood substitutes, and immobilization biotechnology》2000,28(2):173-180
Lomustine (CCNU) microcapsules was prepared by improved recoacervation method, then mixed microcapsules with 0.7% collagen swelling solution to prepare the emulsion, spreaded the emulsion on the plate to form membrane and cross-linked it, the membrane would be planted into body and was expected to release at steady speed. The concentration of CCNU and the CCNU content of microcapsules were measured by ultraviolet spectrophotometry to observe the release of CCNU be slow and constant, approach to 0-class release approximately. 相似文献
962.
Plasma HIV RNA is a useful surrogate marker for predicting HIV-1 disease progression in infected individuals but provides no information regarding the infectious viral titer. Traditional assays of infectious HIV-1 are, however, time consuming, insensitive, use non-standardized reagents and are subject to selection bias introduced by prolonged cultivation. In this pilot study infectious HIV-1 was detected directly in patient plasma using the indicator line HeLa-CD4-CCR5-LTR/beta-gal in a centrifugation-culture method. Replication competent HIV-1 was identified within 2 days of tissue culture inoculation in six (26%) of 23 plasma specimens. The capability of a new cell line, MT4-CCR5-tat, to amplify plasma HIV-1 was also tested. HIV was cultivated from ten (71%) of 14 specimens using MT4-CCR5-tat cells before titering the virus with the indicator cell assay. Using these stable cell lines in refined versions of this assay it may be feasible to develop rapid, simple methods for titering infectious plasma HIV-1 and for testing the susceptibility of the virus to antiretroviral drugs. 相似文献
963.
Jun Wu Mitchell A. Winnik Rajeev Farwaha Jude Rademacher 《Macromolecular chemistry and physics.》2003,204(16):1933-1940
We describe non‐radiative energy‐transfer experiments to measure the rates of polymer interdiffusion in P(MMA‐co‐BA) latex films formed in the presence of poly(vinyl alcohol) (PVOH). PVOH had relatively little effect on the initial efficiency of energy transfer, even when the amount of PVOH was large enough to form the continuous phase. Since ΦET(0) is a measure of the interfacial area between D‐ and A‐labeled cells in the film, we conclude that under these circumstances the dispersed P(MMA‐co‐BA) copolymer is in the form of clusters with many contacts between particles containing D and A labels. These large amounts of PVOH also reduce the amount of polymer diffusion that takes place when the films are annealed. When smaller amounts of PVOH are present, the effects are measurable but much smaller. In the presence of 2 to 17 wt.‐% PVOH, the polymer diffusion rate is retarded. The magnitude of the effect increases with the amount of PVOH present, and the effect is larger at 45 °C than at 63 °C. We show that the PVOH has its largest influence at the very early stages of polymer diffusion.
964.
壳聚糖纳米颗粒包裹对鼠白细胞介素2基因表达和调节小鼠免疫效应的影响 总被引:4,自引:0,他引:4
本实验制备壳聚糖纳米颗粒 (CNP) ,包裹小鼠白细胞介素 2基因 (mIL 2 )真核表达质粒 (VRMIL 2 ) ,肌注接种 2 1d昆明小鼠 ,观察mIL 2基因体内表达及其对免疫应答和免疫保护的影响。实验结果发现 :CNP包裹VRMIL 2注射小鼠血液中IgG、IgM和IgA不同程度地增多 ,均显著高于CNP包裹空白质粒组 (P <0 .0 5 ) ;其血清中IL 2、IL 4和IL 6的含量明显升高 ,与对照组差异显著 (P <0 .0 5 ) ;外周血液的白细胞和淋巴细胞数量也较对照组显著增加。免疫后 35d以大肠杆菌口服攻毒实验小鼠 ,检测发现 :CNP包裹VRMIL 2组小鼠的上述免疫指标除中性粒细胞外均显著多于对照小鼠 ,VRMIL 2接种小鼠均健康存活 ,而对照小鼠均发病 ;尽管CNP包裹VRMIL 2接种小鼠的体液和细胞免疫指标与未包裹VRMIL 2免疫鼠差异不显著 (P >0 .0 5 ) ,但剂量仅为后者的 1/ 5。这些结果表明 :壳聚糖纳米颗粒包裹VRMIL 2可显著提高外源IL 2基因体内表达水平 ,明显增强体液和细胞免疫水平的效应 ,增强对大肠杆菌的抗病力 ,提示壳聚糖纳米颗粒包裹IL 2基因可明显增强动物的体液和细胞免疫 ,可作为有效的抗感染免疫调节剂。 相似文献
965.
胰腺外科学分段的解剖学基础及其意义 总被引:1,自引:0,他引:1
目的:为胰腺外科学分段提供解剖学基础。方法:在64具灌注标本和4具铸型标本上观察胰内动脉分布、吻合。结果:头由胰十二指肠上动脉和胰十二指肠下动脉供血;颈为一乏血管区;体和尾由胰背动脉、胰支、胰大动脉和胰尾动脉供血。结论:全部胰腺可分为左侧段和右侧段 相似文献
966.
We studied pacemaker current (i
f), the inward current activated by hyperpolarization in rabbit sinoatrial (SA) node myocytes, with the permeabilized-patch-clamp
technique. The tyrosine kinase inhibitors genistein (50 μM) or herbimycin A (35 μM) reduced the amplitude of i
f in response to step hyperpolarizations in the diastolic range of potentials. A two-step voltage-clamp protocol revealed that
the reduction in i
f is due to a decrease in maximal i
f conductance. The observed effects are due to tyrosine kinase inhibition since an inactive analog of genistein did not reduce
i
f. To further examine the mechanism of action, we added 2 mM chlorophenylthio cAMP (CPTcAMP, a membrane-permeant cAMP analog)
to the bathing Tyrode, which increased i
f. Genistein still reduced i
f in the presence of CPTcAMP. This suggests that the pathway mediating the actions of tyrosine kinase inhibition on i
f is independent of cAMP- or protein-kinase-A-mediated phosphorylation.
Received: 28 January 1997 / Received after revision: 21 April 1997 / Accepted: 22 April 1997 相似文献
967.
在建立小鼠胸腺基质细胞株时发现小鼠胸腺基质细胞株MTSCB和MTSCC自发产生多核细胞及单核巨细胞,对上述细胞进行了非特异性酯酶(NSE)、酸性磷酸酶(AcP)和琥珀酸脱氢酶(SDH)反应,多核细胞及单核巨细胞的NSE、AcP和SDH活性均强于单核小细胞。在MTSCB中多核细胞的百分数为1.1%;MTSCC中多核细胞为0.6%,实验中对一核细胞和多核细胞出现的百分数与Poisson分布的理论频率进 相似文献
968.
969.
Sequences at the 3'-ends of both positive and negative strands of Hepatitis C virus (HCV) RNA harbor cis-acting elements required for RNA replication. However, little is known about the properties of the negative RNA strand as a template for the synthesis of positive RNA strand. In this study, a purified recombinant HCV RNA-dependent RNA polymerase (RdRp) was used to investigate the synthesis of positive RNA strand using the 3'-terminal region of negative RNA strand ((-)3'T RNA) as template. A mutagenesis analysis was performed to evaluate the role of the 3'-proximal stem-loop and the first 3'-cytidylate (3'C) of the negative RNA strand in the synthesis of the positive RNA strand. A negative RNA strand of wild type (wt) HCV as template was able to direct the synthesis of a full-length positive RNA strand. Deletion of the 3'-proximal stem-loop resulted in an approximately 90% decrease in RNA synthesis. Disruption of the 3'-proximal stem-loop structure by nucleotide substitutions led to a 70-80% decrease in RNA synthesis. However, the restoration of the stem-loop by compensatory mutations in the stem region restored also the RNA synthesis. Likewise, the deletion or substitution of the first 3'C by guanylate (G) led to a 90% decrease in the RNA synthesis; while the substitution by adenylate (A) or uridylate (U) resulted in a 60-80% decrease in the RNA synthesis only. These findings demonstrate that the 3'-proximal stem-loop and the first 3'C of the negative RNA strand of HCV are two cis-acting elements involved in the synthesis of the positive RNA strand. 相似文献
970.
Wu YG Widjaja SL Huang CY Li W Nixon PF Duggleby RG 《Molecular genetics and metabolism》2001,72(3):269-272
One cause of congenital lactic acidosis is a mutation in the E1 alpha-subunit of the pyruvate dehydrogenase multienzyme complex. Little is known about the consequences of these mutations at the enzymatic level. Here we study the A199T mutation by expressing the protein in Escherichia coli. The specific activity is 25% of normal and the K(m) for pyruvate is elevated by 10-fold. Inhibitors of lactate dehydrogenase might be a useful therapy for patients with such mutations. 相似文献