应用3H-TdR掺入法对SMMC-7721细胞株药敏试验条件的探讨与应用

目的探讨3H-TdR掺入法在进行SMMC-7721系细胞肿瘤药敏试验实验时的最佳实验条件.方法确定出3H-TdR掺入法药敏实验时的最适细胞浓度、最适实验药物浓度、3H-TdR掺入最适时间;在最适条件下采用3H-TdR掺入法测定肝癌SMMC-7721细胞株对临床常用的9种抗癌药物的敏感性.结果应用3H-TdR掺入法检测肝癌SMMC-7721细胞株药敏试验的最适实验细胞浓度为1×104个/孔,最适试验药物浓度为1×PPC,3H-TdR最适掺入时间为收集细胞前8 h;肝癌SMMC-7721细胞株对DDP、ADM、5-FU、CPT高度敏感,对MTX、VP-16、MMC、NVB低度敏感,对PYM不敏感.结论 3H-TdR掺入法可用于肿瘤药物敏感性测定并确定出它的最适实验条件.     

Release of newly synthesized h-dopamine in the striatum: An adaptation of the push-pull cannula method to awake restrained and anesthetized rats

The release of newly synthesized ³H-dopamine (³H-DA) was measured in the rat striatum superfused, through a push-pull cannula, with a physiological medium enriched in ³H-tyrosine. The level of spontaneous ³H-DA release was dependent on the topographical localisation of the cannula in the striatum (anterior parts displayed higher levels than posterior ones) and on the anesthetic state (halothane anesthetized rats demonstrated higher levels than awake ones). Inhibition of DA inactivation processes by local application of benztropine (a DA reuptake inhibitor, 10⁻⁶ M) or by IV administration of pargyline (a MAO inhibitor, 100 mg/kg) enhanced the detectable outflow of ³H-DA from the striatum in both halothane anesthetized and awake rats. Local application of D-amphetamine (10⁻⁵ M) or acetylcholine (5 × 10⁻⁵ M) in the presence of eserine (5 × 10⁻⁵ M) evoked respectively a fivefold and a 30% increase in spontaneous ³H-DA release in halothane anesthetized rats. Inhibition of the firing of dopaminergic neurons by IV injection of gamma-hydroxybutyrate (400 mg/kg) produced a 30% decrease in striatal ³H-DA release. The present results demonstrate that the push-pull cannula method is suitable for the study of DA release in both the anesthetized and the awake rat.     

泌尿系感染病原菌的变迁及耐药性分析

目的了解近年来泌尿系感染病原菌的变迁及耐药现状. 方法应用回顾性调查分析方法,对我院1997至2000年间泌尿系感染检测的1 026株病原菌的分布及耐药性进行统计分析. 结果在泌尿系感染的病原菌中,G+球菌上升,G-杆菌下降,真菌上升,其中粪肠球菌上升和变形菌属下降差异有显著性(P<0.05),药敏实验结果对以往常用的抗菌药物青霉素类、复方新诺明、红霉素、诺氟沙星及一代头孢显示较高的耐药性,2000年耐药率>81.6%,对三代头孢、环丙沙星、庆大霉素呈中度耐药,耐药率在42.9%～78.3%,对阿米卡星及头孢哌酮/舒巴坦呈轻度耐药,耐药率<36.7%. 结论随着抗生素的更新换代、人口老龄化及医院感染等因素的变化,泌尿系感染病原菌的分布及耐药性均发生了变迁.     

Cough and converting enzyme inhibitors

Persisting cough developed in three children treated with converting enzyme inhibitors. The symptoms disappeared within 3–7 days after withdrawing medication. These observations in children complement previous reports in adults and indicate that cough may be induced by treatment with these agents.     

Olfactory Absorption of Insulin to the Brain

A vast number of potent neuropharmaceuticals, many of which are peptides, are excluded from entry into the brain because of the highly selective blood-brain barrier. The fact that a number of drugs have been shown to be transported directly to the central nervous system following application to the olfactory region of the nose is therefore of major interest. In the present study, the feasibility of delivering peptides to the brain via the olfactory route was assessed using insulin as a model peptide. Systemic hyperinsulinemia induced by subcutaneous injection did not significantly reduce the amount of ¹²⁵I-insulin transported from the nose to the brain in vivo, which suggests that the impact of systemic absorption on drug transport is minimal. A linear relationship was seen between insulin accumulation in the brain and the dose applied, without any relevant saturation. Contrary to what was expected, both systemic and olfactory absorption of insulin was enhanced when the pH of the medium was near the isoelectric point. The amount absorbed to the brain was found to be linearly related to the net charge of the molecule (r = -0.61; n = 20). It was concluded that insulin gains access to the central nervous system from the olfactory region of the nose by a nonspecific pathway. The olfactory route may therefore become an important means to deliver peptides to the brain.     

Differential Stimulation of Noradrenaline Release by Reversal of the Na+/Ca2+ Exchanger and Depolarization in Chromaffin Cells

We compared the effectiveness of Ca²⁺ entering by Na⁺/Ca²⁺ exchange with that of Ca²⁺ entering by channels produced by membrane depolarization with K⁺ in inducing catecholamine release from bovine adrenal chromaffin cells. The Ca²⁺ influx through the Na⁺/Ca²⁺ exchanger was promoted by reversing the normal inward gradient of Na⁺ by preincubating the cells with ouabain to increase the intracellular Na⁺ and then removing Na⁺ from the external medium. In this way we were able to increase the cytosolic free Ca²⁺ concentration ([Ca²⁺]_c) by Na⁺/Ca²⁺ exchange to 325 ± 14 nM, which was similar to the rise in [Ca²⁺]_c observed upon depolarization with 35 mM K⁺ of cells not treated with ouabain. After incubating the cells with ouabain, K⁺ depolarization raised the [Ca²⁺]_c to 398 ± 31 nM, and the recovery of [Ca²⁺]_c to resting levels was significantly slower. Reversal of the Na⁺ gradient caused an −6-fold increase in the release of noradrenaline or adrenaline, whereas K⁺ depolarization induced a 12-fold increase in noradrenaline release but only a 9-fold increase in adrenaline release. The ratio of noradrenaline to adrenaline release was 1.24 ± 0.23 upon reversal of the Na⁺/Ca²⁺ exchange, whereas it was 1.83 ± 0.19 for K⁺ depolarization. Reversal of the Na⁺/Ca²⁺ exchange appeared to be as efficient as membrane depolarization in inducing adrenaline release, in that the relation of [Ca²⁺]_c to adrenaline release was the same in both cases. In contrast, we found that for the same average [Ca²⁺]_c, the Ca²⁺ influx through voltage-gated channels was much more efficient than the Ca²⁺ entering through the Na⁺/Ca²⁺ exchanger in inducing noradrenaline release from chromaffin ceils. This greater effectiveness of membrane depolarization in stimulating noradrenaline release suggests that there is a pool of noradrenaline vesicles which is more accessible to Ca²⁺ entering through voltage-gated Ca²⁺ channels than to Ca²⁺ entering through the Na⁺/Ca²⁺ exchanger, whereas the adrenaline vesicles do not distinguish between the source of Ca²⁺.     

尼莫地平控释片释放度试验研究

本文研究了尼莫地平控释片的释放度试验方法——转篮法，释放介质为含有２２％异丙醇的０．１ｍｏｌ·Ｌ－１盐酸液；磷酸盐缓冲液（ｐＨ５．８）和ｐＨ７．２的溶液。含量测定方法：紫外分光光度法，在三种介质中尼莫地平分别在１～３０μｇ·ｍｌ－１，１０～５０μｇ·ｍｌ－１和１０～５０μｇ·ｍｌ－１的范围内，浓度与吸收度有较好的线性关系。回归方程分别为Ａ＝０．６１５Ｃ＋０．０２３（ｒ＝０．９９９９）；Ａ＝０．０６１４Ｃ＋０．０１２（ｒ＝０．９９９５）；Ａ＝０．０６１２Ｃ＋０．００８８（ｒ＝０．９９９９）。平均回收率分别为９９．６３％，９９．９８％及１００．７７％，ＲＳＤ（％）分别为１．３４％，１．５９％及１．４１％。本方法的体外释放百分率与体内吸收分数有较好的相关性（ｒ＝０．９９１）。     

头孢氨苄缓释片在健康人体内的生物利用度和药物动力学

目的:比较头孢氨苄缓释片和普通胶囊的生物利用度和药物动力学。方法：10例健康志愿者分别单剂量口服500mg头孢氨苄缓释片和普通胶囊，血药浓度测定方法为HPLC法。结果：两种剂型体内过程均符合一室开放模型，缓释片的达峰时间（Tmax）为（2．58±0．59）h，峰浓度（Cmax）为（10．08±1．68）μg／ml．吸收速率常数（Ka）为（0．90±0．53）／h，消除速率常数（Ke）为（0.26±0.02）／g，半衰期（T1／2）为（2.67±0.23）h，清除率（Cl）为（6.93±1.71）L／h，分布容积（Vd）为（26.66±6.72）L，药一时曲线下面积（AUC）为（48.31±9.32）μg·h／ml。两种剂型T一C一Ka、Ke、T1／2和Cl均存在显著性差异（P＜0．01），Vd、AUC无显著性差异（P＞0．05）；缓释片的相对生物利用度为（104．90±8．35）％。结论：缓释片的吸收减慢，Tmax推迟，T1／2延长，可减少服药次数，提高药物治疗的顺应性。     

Preparation and evaluation of temperature sensitive liposomes containing adriamycin and cytarabine

Temperature sensitive liposomes (TSL) containing adriamycin (ADM) and cytarabine (Ara-C) were prepared. ADM and Ara-C were selected as model compounds of amphiphilic and hydrophilic drug, respectively. Encapsulation efficiency of ADM entrapped into TSL was about twice greater than that of Ara-C. It might be due to different polarity of the drugs. Lipid compositions of TSL had no effect on the encapsulation efficiency of drugs. Thermal behavior of TSL using a differential scanning calorimetry (DSC) was also investigated. Phase transition temperature (T_c) of TSL was dependent on the lipid compositions of TSL.ADM broadened thermogram of TSL but Ara-C did not. However, T_c of TSL was not changed by any drug. Release rate of drugs was highly dependent on temperature. The release profile of ADM was similar to that of Ara-C. The maximum release rate of drugs from TSL was occurred at the near T_c and observed at 39–41°C for DPPC (Dipalmitoylphosphatidylcholine) only, 52–54°C for DSPC (Distearoylphosphatidylcholine) only, 41–43°C for DPPC and DSPC (3∶1), and 43–45°C for DPPC and DSPC (1∶1), respectively. Effect of human serum albumin (HSA) on the release rate of ADM was investigated. HSA had no significant effect on the release of ADM below T_c. However, ADM release from TSL was increased at the near and above T_c. The HSA-induced leakage of drug may result from the interaction of liposomal constituents with HSA structure at the near T_c. From the fact that the release profiles of ADM from freshly prepared TSL and stored TSL for 1 week at 4°C was not changed, the TSL was considered to be stable for at least 1 week at 4°C. Based on these findings, TSL may be useful to deliver drugs to preheated target sites due to its thermal behaviors.     

Biological characterization of glutaraldehyde-modified Parietaria judaica pollen extracts

BACKGROUND: Allergoids are widely used in specific immunotherapy (SIT) for the treatment of IgE-mediated allergic diseases, but all techniques for standardization of conventional allergic extracts may not be appropriate for standardization of a glutaraldehyde (GA)-modified extract because of the unique characteristics of these extracts. OBJECTIVE: To assess an accurate methodology for standardization of chemically modified extracts. METHODS: GA-modified extracts from Parietaria judaica pollen were purified by diafiltration. Biochemical properties were investigated by determination of amino groups, chromatography, and SDS-PAGE. The IgE-binding activity was determined by skin prick test, enzyme allergosorbent test inhibition, basophil activation, and histamine release tests. Peripheral blood mononuclear cells (PBMCs) from P. judaica pollen-allergic subjects were stimulated with either native or allergoid extracts, and proliferation was measured. RESULTS: Biochemical data indicated a high degree of allergen polymerization resulting in extract components higher than 100 kDa. IgE-binding activity, both in vivo and in vitro, was reduced by more than 99.8%. Both allergen and allergoid induced PBMC proliferation and synthesis of blocking IgG antibodies at similar rates. Moreover, no evidence of introduction of new determinants by chemical modification was found. CONCLUSIONS: The preparation of GA-modified extracts by diafiltration is faster and more reliable than previous chromatographic methods. These modified extracts have drastically reduced their allergenicity while maintaining their immunogenicity, and therefore they can be used in safer and shortened schedules of SIT.