Effect of a Water‐Soluble Polymer on Polymer Interdiffusion in P(MMA‐co‐BA) Latex Films

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 Φ_ET(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.

Schematic representation of an energy transfer experiment, which monitors polymer interdiffusion in a latex film.     

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

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。     

胰腺外科学分段的解剖学基础及其意义

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     

Tyrosine kinase inhibition reduces i f in rabbit sinoatrial node myocytes

 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     

小鼠胸腺基质细胞株中细胞多核化现象探讨

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     

鼻腔外侧壁的应用解剖

在60个头颅(男34,女26)120侧鼻腔外侧壁上观察测量了以下诸结构,结果:上鼻甲长15.9±2.9mm,宽4.7±1.1mm;中鼻甲长36.5±3.3mm,宽10.4±3.4mm;下鼻甲长42.7±3.6mm,宽12.3±1.7mm;半月裂长16.6±2.3mm;钩突长20.7±3.1mm,宽4.3±1.7mm;筛泡长19.2±4.1mm,高6.5±2.1mm,另外还测量了前鼻棘距上述各结构的距离.     

Two cis-acting elements in negative RNA strand of Hepatitis C virus involved in synthesis of positive RNA strand in vitro

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.     

Congenital lactic acidosis: evaluation of the properties of the a199t natural variant of human pyruvate dehydrogenase e1alpha by in vitro mutation

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.     

肝素酶与肿瘤转移

肿瘤细胞实现扩散、转移 ,与免疫细胞趋向炎症反应区一样 ,必须首先穿越由细胞外基质和基底膜组成的屏障。该屏障主要由两种成分构成 :一是结构蛋白 ,包括胶原、层粘素、纤维结合素和玻璃体结合素等 ;二是糖氨聚糖 ,其主要成分是硫酸乙酰肝素蛋白多糖 (ｈｅｐａｒａｎｓｕｌｆａｔｅｐｒｏｔｏｇｌｙｃａｎ ,ＨＳＰＧ)。ＨＳＰＧ主要由一个蛋白核心和数个与之共价连接的线性硫酸乙酰肝素 (ｈｅｐａｒａｎｓｕｌｆａｔｅ ,ＨＳ)侧链组成[1] 。起初认为 ,结构蛋白的破坏是肿瘤细胞转移的决定性步骤 ,因此 ,在过去的 10多年中 ,研究兴趣大多集…     

Multicenter analytical evaluation of an automated immunoassay for total plasma homocysteine

A fully automated immunoassay for total plasma homocysteine assay was evaluated at four centers. To measure total homocysteine, oxidized forms of homocysteine in serum and plasma were reduced by dithiothreitol and assayed by a competitive fluorescence polarization technique. The assay had within-run precision from 0.9 to 3.0% and total precision from 2.8 to 4.1% for control materials with homocysteine concentrations of approximately 7, 12.5, and 25 micromol/L, a sensitivity of 0.35 micromol/L, good parallelism upon dilution, and analytical recovery ranging from 97.4 to 103.8%. The immunoassay correlated with four different HPLC assays for homocysteine, yielding a slope of 0.98, an intercept of -0.19 micromol/L, and a correlation coefficient of 0.966 for 440 paired samples. The reference range, determined with plasma samples from 609 males and 600 females, yielded a mean of 9.17+/-2.86 micromol/L, with a central 95% range of 4.78-15.43 micromol/L. The immunoassay is a suitable alternative to HPLC and may be useful in screening persons with high risk of coronary artery disease.