丙氨酰-谷氨酰胺在全合一肠外营养液中的稳定性

目的 观察丙氨酰-谷氨酰胺对全合一肠外营养液稳定性尤其是脂肪乳剂稳定性的影响。方法将丙氨酰-谷氨酰胺分别加入3种不同配方的全合一肠外营养液中，在不同温度下、24小时内取样观察外观变化，测定pH值、渗透压值。观察脂肪乳剂在加入丙氨酰-谷氨酰胺后颗粒大小及形态有无改变并计算平均粒径。结果不同配方全合一肠外营养液加入丙氨酰-谷氨酰胺后，其外观、pH值、渗透压值未见明显改变，脂肪乳剂颗粒大小及形态亦无明显变化。临床应用100人次，未见不良反应。结论丙氨酰-谷氨酰胺可加入全合一肠外营养液中进行配伍使用。     

准分子激光原位角膜磨镶术后泪膜变化的观察

目的:观察准分子激光角膜原位磨镶术(laser in situ keratomileusis,LASIK)后泪膜功能的改变,探讨LASIK术后发生眼干现象的原因.方法:对广州医学院第二附属医院眼科100例近视患者186只眼进行LASIK手术,分别测定其术前,术后1周、1个月、3个月的泪液分泌量(用Schirmer I实验测定)、泪膜破裂时间(break-up time,BUT)和角膜荧光素染色试验.结果:①Schirmer Ⅰ值:术前为(15.89±6.70)mm,术后1周为(12.08±7.30)mm,术后1月为(10.43±5.52)mm,术后3月为(11.56±6.82)mm.②平均BUT值:术前为(12.83±5.04)s,术后1周为(9.07±6.40)s,术后1月为(8.74±7.56)s,术后3月为(10.23±5.76)s.③术后1周角膜荧光素染色比术前加重.结论:LASIK术后早期可导致泪膜稳定性下降,泪液分泌减少,产生干眼症状,主要原因可能与术后角膜知觉减退有关.     

Fetal striatal transplants reinstate the electrophysiological response of pallidal neurons to systemic apomorphine challenge in rats with excitotoxic striatal lesions

Previous studies with single-unit recording and 2-[14C]deoxyglucose quantitative autoradiography have shown that systemic administration of apomorphine increases the functional activity of pallidal neurons, and that the enhancement in the globus pallidus (GP) activity is abolished by striatal lesions. The present study employing electrophysiological techniques tested whether embryonic striatal tissue implanted in the excitotoxically damaged striatum of rats may affect the lesion-induced alteration in the neuronal response of GP to apomorphine. Systemically administered apomorphine significantly increased spontaneously firing rates of GP cells. The blockade of dopamine receptors with haloperidol reversed the increased rate to baseline levels. Quinolinate-induced striatal lesions attenuated the rate-increasing effect of apomorphine. Embryonic striatal grafts placed in the lesioned striatum restored the response of GP cells to systemic apomorphine. The graft-mediated restoration of the GP neuron response to apomorphine were accompanied by an improvement in the motor asymmetry induced by this drug. Considering previous anatomical data to demonstrate extensive innervation of the GP by embryonic striatal grafts, the present results suggest that the grafts reconstruct the functional striatopallidal pathway which is capable of transmitting apomorphine-induced changes in the neuronal activity.     

微生物法考察威替米星注射液的生物学稳定性

目的:对威替米星注射液的生物学稳定性进行研究。方法:将威替米星注射液置于不同条件下考察其稳定性,采用微生物法和无菌检查法对放置样品的效价稳定性及是否长菌进行检测。结果:本品经高温试验(60.0±s2.0)℃10d,光照试验(4500lx)10d,加速试验[相对湿度(75±5)%,(40.0±2.0)℃]6mo,长期试验[相对湿度(60±5)%,(25.0±2.0)℃]12mo,其效价均未有明显变化,无菌检查亦符合规定。结论:本品在各放置条件下稳定性良好。     

Stability and specificity of heterodimer formation for the coiled‐coil neck regions of the motor proteins Kif3A and Kif3B: the role of unstructured oppositely charged regions

Abstract: We investigated the folding, stability, and specificity of dimerization of the neck regions of the kinesin‐like proteins Kif3A (residues 356–416) and Kif3B (residues 351–411). We showed that the complementary charged regions found in the hinge regions (which directly follow the neck regions) of these proteins do not adopt any secondary structure in solution. We then explored the ability of the complementary charged regions to specify heterodimer formation for the neck region coiled‐coils found in Kif3A and Kif3B. Redox experiments demonstrated that oppositely charged regions specified the formation of a heterodimeric coiled‐coil. Denaturation studies with urea demonstrated that the negatively charged region of Kif3A dramatically destabilized its neck coiled‐coil (urea_1/2 value of 3.9 m compared with 6.7 m for the coiled‐coil alone). By comparison, the placement of a positively charged region C‐terminal to the neck coiled‐coil of Kif3B had little effect on stability (urea_1/2 value of 8.2 m compared with 8.8 m for the coiled‐coil alone). The pairing of complementary charged regions leads to specific heterodimer formation where the stability of the heterodimeric neck coiled‐coil with charged regions had similar stability (urea_1/2 value of 7.8 m ) to the most stable homodimer (Kif3B) with charged regions (urea_1/2 value of 8.0 m ) and dramatically more stable than the Kif3A homodimer with charged regions (urea_1/2, value of 3.9 m ). The heterodimeric coiled‐coil with charged extensions has essentially the same stability as the heterodimeric coiled‐coil on its own (urea_1/2 values of 7.8 and 8.1 m , respectively) suggesting that specificity of heterodimerization is driven by non‐specific attraction of the oppositely unstructured charged regions without affecting stability of the heterodimeric coiled‐coil.     

The effects of sucrose on stability of human brain natriuretic peptide [hBNP (1–32)] and human parathyroid hormone [hPTH (1–34)]

Abstract: Although the effect of sucrose on the physical stability of proteins has been well documented, its impact on their chemical stability is largely unknown. The aim of this study was to investigate the potential effects of sucrose on the structural conformation of human brain natriuretic peptide [hBNP (1–32)] and the synthetic human parathyroid hormone [hPTH (1–34)], and link these effects to chemical degradation pathways of these peptides. The stability of hBNP (1–32) and hPTH (1–34) was studied at pH 5.5. Aggregation was monitored using size exclusion high‐performance liquid chromatography (SE‐HPLC), whereas oxidation and deamidation products were measured by reversed phase (RP) HPLC. Fourier transform infrared (FT‐IR) spectroscopy was used to study the peptides’ conformation. Sucrose retarded aggregation, deamidation, and oxidation of hBNP (1–32) and hPTH (1–34), with a maximum effect at relatively high concentrations (as much as 1 m ). FT‐IR spectroscopy indicated that sucrose maintained the native conformation of hBNP (1–32) and induced small conformation changes in the hPTH (1–34) structure. Sucrose enhanced the stability of hBNP (1–32) and hPTH (1–34) in liquid formulations. The stabilizing effect of sucrose was due to a large extent to retardation of oxidation and deamidation of hBNP (1–32) and hPTH (1–34).     

蜂毒体外抗凝血活性稳定性考察

目的考察蜂毒体外抗凝血活性的稳定性。方法采用凝血酶原活化时间法进行测定。结果供试品在 0～ 6 .0mg/ml浓度范围内 ,凝血时间具有明显的浓度依赖关系 ,相关系数为 0 .972 2 ;蜂毒的抗凝血活性在光照及酸性条件下相对稳定 ,其水溶液在强碱性条件下易降解 ,6 0℃条件下 6h内活性相对稳定 ,在胃蛋白酶及胰蛋白酶作用下 5min开始失活。结论蜂毒在低温及生理pH条件下较稳定 ,水溶液易失活 ,在有蛋白酶存在下极易失活     

重组L-门冬酰胺酶的聚乙二醇化学修饰及修饰后酶的稳定性研究

目的单甲氧基聚乙二醇 (mPEG)化学修饰大肠杆菌重组L 门冬酰胺酶 (L ASP) ,考察经过修饰的酶的稳定性。方法N 羟基琥珀酰亚胺 (NHS)活化酯法活化mPEG ,生成的单甲氧基聚乙二醇琥珀酰琥珀酸亚胺酯 (SS mPEG)按不同摩尔比例与L ASP偶联 ,确定适合的反应时间和反应pH值。通过聚乙二醇化学修饰后的酶 (L ASP PEG) ,酶活力和纯度通过奈氏法和丙烯酰胺凝胶电泳 (SDS PAGE)检测 ,高效液相色谱检测L ASP PEG相对分子质量并考察了L ASP PEG体外稳定性等。结果SDS PAGE显示mPEG已经偶联到L ASP分子上 ,以两者摩尔比 1 0∶1为最佳 ,反应pH条件为 8.5 ,获得的L ASP PEG平均比活单位为 6 4 .8IU/mg ,相对分子质量为 30 1 80 0 ,体外稳定性高于L ASP。结论此实验确定了mPEG化学修饰L ASP最佳反应条件为 2 5℃反应 30min ,两者投料摩尔比为 1 0∶1 ,获得的L ASP PEG比L ASP稳定性高     

硝酸甘油注射液稳定性研究

目的通过考察不同pH值的无水乙醇对硝酸甘油注射液稳定性的影响,筛选出最适于硝酸甘油注射液生产的无水乙醇。方法用高温加热破坏试验及长期试验的方法研究硝酸甘油注射液的稳定性,考察指标pH值和含量。结论碱性杂质含量低的无水乙醇配制的硝酸甘油注射液稳定性最好,适于硝酸甘油注射液的生产。     

水杨酸咪唑栓的稳定性考察

目的考察光、温度、湿度等多种因素对水杨酸咪唑栓稳定性的影响。方法建立质量标准,分别进行各影响因素试验、加速试验、室温留样检查观察和分析水杨酸咪唑栓的性状、含量及其他项目。结果本制剂对高湿度、低温(4℃)稳定,但光照对本品外观颜色有一定影响,在高温40～80℃放置会软化变形。结论本品应避光,35℃以下温度保存。