The Binding of Cyclosporin A to Human Plasma: An in Vitro Microdialysis Study

Purpose. The human plasma binding of cyclosporin A was studied in vitro using the technique of microdialysis. The effect of temperature on the overall binding interaction between cyclosporin A and human plasma was also investigated. Methods. Flow-through loop-type microdialysis probes were constructed from fused silica tubing and regenerated cellulose tubing with a MWCO of 13000 daltons. Probes were perfused with phosphate buffer (0.5 µl/min) and the concentration of ³H-cyclosporin A in the well-mixed medium (plasma or buffer) was 1200 ng/ml. Relative recoveries of cyclosporin A from plasma or buffer were determined for each probe by separate experiments to measure the solute gain or loss with reference to the perfusate. Results. Recoveries determined by loss were significantly greater than those determined by gain and in each case temperature dependent, with higher recoveries at higher temperatures. The plasma free fraction of cyclosporin A calculated from the recovery data and the perfusate to plasma concentration ratios was dependent on temperature in a log-linear fashion. Mean ± s.d. plasma free fractions expressed in percent were 33.5 ± 4.6, 17.9 ± 3.6, 6.2 ± 0.8, 3.0 ± 0.6, and 1.5 ± 0.2 at temperatures of 4, 10, 20, 30, and 37°C, respectively. Assuming that the enthalpy of binding is constant over the temperature range studied and pseudo-first order conditions exist, the binding reaction at these temperatures was spontaneous, endothermic (H = 74.0 kJ/mole), and entropically driven (S = 0.274 kJ/mole/deg). Conclusions. These results show that the free fraction of cyclosporin A in human plasma is dependent on temperature with the fraction unbound decreasing with temperature in the range of 4 to 37°C. The thermodynamic parameters for the binding of cyclosporin A to plasma components indicate that the reaction is a spontaneous endothermic reaction that is mainly entropy driven, similar to the partitioning of lipophilic molecules from an aqueous to a hydrophobic phase. Moreover, these results show that microdialysis is a feasible method to determine the binding interactions between plasma and cyclosporin A, which indicates the method may be suitable for other difficult binding studies where the solutes have nonspecific binding to separation devices.     

Prognostic significance of the evolution of left ventricular ejection fraction in patients with acute myocardial infarction not treated with thrombolytic therapy

Several controlled trials on the thrombolytic treatment of acutemyocardial infarction (AMI) have failed to demonstrate thatthrombolysis has a simultaneous positive effect on left ventricularfunction and survival. One explanation may be that spontaneouschanges in left ventricular function occurred during the progressionof AMI in control patients. The aim of this study was to evaluatethe spontaneous evolution of left ventricular ejection fraction(LVEF) and its prognostic influence on early (1 month) and late(1 year) mortality in patients with AMI. We studied 216 patientsadmitted to our CCU within 24 h of the onset of symptoms. LVEFwas determined by radionuclide ventriculography on admission(RNV1) and at the end of the necrotic phase (RNV2). Fourteenpatients died before RNV2. On the basis of LVEF values at RNV1,the remaining 202 patients were divided into two groups: thosewith a normal LVEF (55%), and those with an abnormal LVEF (<55%). Among patients with a normal LVEF at RNV1 (64 patients) a significantincrease (>12%) in LVEF at RNV2 was observed in 12.5%, asignificant decrease (>12%) in 12.5% and no change at allin 75%. All of these patients survived, regardless of the evolutionof LVEF. In patients with an abnormal LVEF at RNV1 (138) a significantincrease (>5%) in LVEF at RNV2 was observed in 72.5%, a significantdecrease (>5%) in 6.5% and no change at all in 21%. In patientswith a LVEF increase, both early and late mortality were significantlylower than in patients with a LVEF decrease: (early mortality4% vs 55.5%, P<0.001; late mortality 6% vs 66.6%, P<0.001)respectively. In patients without any LVEF change, mortalitywas significantly lower than in patients with a LVEF decrease:(early mortality 10% vs 55.5%, P = 0.01; late mortality 14%vs 66.6%, P=0.004) respectively. In conclusion, our data demonstrate that a significant increasein LVEF occurs in most patients with an early depression ofleft ventricular function. This behaviour is associated witha low early and late mortality in comparison with the patientswith a LVEF decrease and is independent of thrombolytic treatment.When the early measurement of LVEF is normal the prognosis isnot influenced by LVEF evolution. These findings must be keptin mind when LVEF is used as a prognostic index and as an end-pointfor the evaluation of the effects of thrombolytic therapy.     

Radioisotope assessment of heart damage in hypertransfused thalassaemic patients

Twenty-five thalassaemic patients treated with repeated blood transfusion (BT) and intensive iron removal therapy were studied by echocardiography and rest/stress equilibrium gated radionuclide angiocardiography (EGNA). Stress left ventricular ejection fraction (LVEF) showed an important negative correlation with number of BTs (r = –0.75). Abnormal values of stress LVEF were measured after 200 BTs: these data demonstrate the effectiveness of stress LVEF in the follow-up of patients who have undergone repeated BTs and the clinical importance of intensive chelation therapy. Peak filling rate did not show diagnostic value in the early detection of iron cardiotoxicity. However, its inverse correlation with BT (r = –60) indicates that iron overload depresses the diastolic parameters.     

Prognostic potential of flow cytometric S-phase and ploidy prospectively determined in primary breast carcinomas

In a prospective study of a consecutive breast cancer series accumulated in the period 1978–82, the S-phase fraction (SPF) and ploidy status were determined by flow cytometry performed on cell nuclei derived from samples of 580 primary tumors. Sixty percent of the tumors were non-diploid. After correction for debris the median SPF values were 7.3% overall, 12% for non-diploid tumors, and 2.9% for diploid tumors (2.6% when nodal subsets N2 and N3 and cases with metastases at presentation were excluded). The SPF values correlated both to tumor size (p=0.008) and to the number of positive axillary lymph nodes (p=0.03).At clinical follow-up in 1986, 467 unilateral breast cancer patients who had undergone radical treatment for cure could be evaluated with respect to the prognostic value of both the SPF value and ploidy status. The median duration of follow-up was then 59 months (range 2–90), and the median time-to-recurrence 24 months (range 2–69, n=137).At follow-up in 1991, 201/467 of the patients had died, the median duration of follow-up being 50 months (range 2–126) for the deceased, and 119 (range 6–148) for the survivors. In multivariate analysis (Cox's proportional hazards models), the strongest independent predictors of distant recurrence-free survival (DRFS) were the number of positive axillary lymph nodes (p<0.0001), the debris-corrected SPF value alone (p=0.003,versus p=0.05 for uncorrected value), and ploidy status combined with the corrected SPF value (p=0.0002). When age was taken into account, both the corrected SPF value and the ploidy-SPF combination were predictors of crude survival (p=0.006 and p=0.002, respectively).In univariate life-table analysis, the 5-year DRFS rate was 93% in node-negative (N0) cases with an SPF<7.3%, as compared to 80% in those with an SPF7.3% (p=0.005). Among node-positive cases, the prognostic value of the SPF was confined to those with 1–3 positive nodes, the 5-year DRFS rate being 68% in cases with an SPF<7.3%, as compared to 40% in cases with an SPF7.3% (p=0.01).Ploidy status and SPF were combined to form four groups: diploid & SPF<2.6% (DL), diploid & SPF2.6% (DH), non-diploid & SPF<12% (NDL), and non-diploid & SPF12% (NDH). Among node-negative patients, the DRFS rate fell from 95% in the DL group to 87% in the NDL group, with the DH group at an intermediate level, as compared with 74% (p=0.03) for the NDH group which accounted for the bulk of the early distant recurrences. Among patients with 1–3 positive lymph nodes, the 5-year DRFS rate was 68% in both the groups with low SPF values (DL and NDL), as compared with 45% in the DH group (p=0.03), and 37% in the NDH group (p=0.006).In this study, the flow cytometry SPF value, alone or in combination with ploidy status, yielded the most profound additional prognostic information, enabling both node-negative patients with a high probability of cure and patients at risk of early relapse to be identified. Among node-positive patients, the prognostic value of the SPF value was confined to those with 1–3 positive axillary lymph nodes (the predominant node-positive subgroup), enabling a high and a low DRFS rate subgroup to be distinguished – a useful distinction where selection for adjuvant drug treatment is concerned. As the predictive strength of the SPF value was enhanced when correction was made for debris, we would recommend that the effect of such factors as debris be minimized as far as possible when flow cytometry-derived SPF values are to be used for prognostic purposes.     

板蓝根抑菌抗炎活性部位的评价

目的：评价和比较板蓝根5个化学部位抑菌、抗炎活性的强弱。方法：采用管碟法测定板蓝根不同化学部位对于金黄色葡萄球菌、铜绿假单胞菌的敏感性，观察对二甲苯所致小鼠耳廓肿胀的抑制作用。结果：板蓝根Ⅴ部位体外抑菌活性最强，Ⅴ部位具有显著的抗炎活性。结论：板蓝根中高极性成分具有很强的药理活性，是其发挥清热解毒功效的物质基础。     

盐酸洛美沙星左氧氟沙星治疗泌尿生殖系感染

目的观察评价盐酸洛美沙星与左氧氟沙星治疗泌尿系感染的疗效及安全性.方法69例病人随机分成两组,治疗组38例,用盐酸洛美沙星0.2g,po,bid;对照组31例,用左氧氟沙星0.1g,po,tid,疗程均为7～14d.结果治疗组临床有效率为92.1%,细菌清除率为91.5%;对照组分别为90.3%和92.5%;两组间无显著性差异(P＞0.05).结论盐酸洛美沙星治疗泌尿生殖系感染疗效确切,安全方便,不良反应小.     

纳洛酮治疗肺性脑病45例临床观察

目的：研究纳洛酮对肺性脑病患者的治疗效果。方法：68例出现肺性脑病的患者被随机分成两组。治疗组45例采用纳洛酮治疗，对照组23例采用尼可刹米和洛贝林治疗。结果：治疗组在8h内较对照组有较高的苏醒率，且苏醒所需时间短。8h后治疗组的心率、呼吸频率以及PaCO2的平均水平较对照组低，而PaO2较对照组高。结论：纳洛酮能有效地改善患者的通气，明显地加快肺性脑病患者的苏醒。     

中药质量监控之我见

本文在对现有的指标成分检测及指纹图谱质量控制模式进行分析的基础上，结合本实验室的研究工作，提出有效成分检控应是中药质量控制的发展方向，并阐述了实施有效成分检控这一质量控制模式的方法与可能性。     

大青叶抗内毒素活性部位筛选

目的 评价和比较大青叶5个化学部位的抗内毒素作用。方法 采用动态浊度法测定细菌内毒素浓度，观察大青叶不同化学部位对放线菌素D敏化小鼠内毒素致死攻击的保护作用。并以内毒素制备家兔发热模型，测定其肛温变化。结果 大青叶Ⅳ部位能直接中和降解内毒素，显著降低内毒素的致热性和致死性。结论 大青叶Ⅳ部位具有显著的体内外抗内毒素活性。     

苦参碱对豚鼠心肌电生理及机械特性的影响

目的　观察苦参碱对离体豚鼠右心室乳头状肌动作电位及收缩力 (Fc)的影响 ,以探讨其抗心律失常的作用机制。方法　采用标准玻璃微电极技术记录心肌细胞动作电位 ,肌力换能器同步记录心肌收缩力。结果　苦参碱 10、2 5、5 0 μmol·L-1可浓度依赖性地延长快反应动作电位(FAP)的复极 5 0 %时程 (APD50 )、复极 90 %时程 (APD90 )和有效不应期 (ERP) ,延长高钾除极组织胺及氯化钡诱发的慢反应动作电位 (SAP)的APD50 、APD90 ;但对FAP、SAP的动作电位振幅 (APA)、0期最大除极速率 (Vmax)及Fc无明显影响。结论　结果提示苦参碱对心肌细胞钠、钙离子通道无明显影响 ,其延长APD的作用可能是阻断心肌钾通道的结果。