CD4+CD25+调节性T淋巴细胞在儿童传染性单核细胞增多症的变化及作用

目的 观察儿童传染性单核细胞增多症（IM）治疗前后外周血T淋巴细胞亚群和CD4⁺CD25⁺调节性T淋巴细胞（Treg细胞）比例变化,分析Treg对IM的影响。方法 选取2017年1月至2018年5月安徽医科大学第二附属医院儿科收治的IM患儿60例作为观察组,以同期于本院儿童保健门诊行体检的40例健康儿童作为对照组,采用流式细胞术检测观察组治疗前、后及对照组的外周血T细胞亚群（CD3⁺T细胞、CD3⁺CD4⁺T细胞、CD3⁺CD8⁺T细胞比例,CD4/CD8比值）、CD4⁺CD25⁺调节性T淋巴细胞比例,对比分析两组患者机体细胞免疫功能的变化。结果 观察组治疗前CD3⁺T细胞比例、CD3⁺CD8⁺T细胞比例显著高于对照组;CD3⁺CD4⁺T细胞比例、CD4/CD8比值低于对照组,差异均有统计学意义（P <0.05）。观察组治疗后CD3⁺T细胞比例、CD3⁺CD8⁺T细胞比例均低于观察组治疗前;CD3⁺CD4⁺T细胞比例、CD4/CD8比值高于治疗前,差异均有统计学意义（P <0.05）。观察组治疗前外周血Treg细胞比例低于正常对照组,差异有统计学意义（P <0.05）;而观察组治疗后外周血Treg细胞比例高于治疗前,差异有统计学意义（P <0.05）。结论 IM患儿存在T细胞亚群比例的变化,Treg细胞水平的降低,可能参与IM患儿疾病的发生发展过程。     

安替可胶囊联合TP方案治疗晚期食管鳞癌的临床研究

目的 探讨安替可胶囊联合TP方案（紫杉醇＋顺铂）治疗晚期食管鳞癌的临床疗效。方法 选取2019年1月—2022年1月河南省人民医院收治的100例术后复发转移、晚期转移无法手术治疗的晚期食管鳞癌患者,将所有患者随机分为对照组（50例）和治疗组（50例）。对照组第1天静脉滴注紫杉醇注射液135 mg/m²,第1～3天静脉滴注顺铂注射液75 mg/m²。治疗组于对照组基础上口服安替可胶囊,2粒/次,3次/d。3周为1个治疗周期,两组患者持续治疗3个周期。观察两组的临床疗效,比较两组肿瘤标志物[鳞状细胞癌抗原（SCC-Ag）、细胞角蛋白19片段（CYFRA21-1）、癌胚抗原（CEA）、糖类抗原125（CA125）]、细胞免疫功能淋巴细胞（CD3⁺、CD4⁺、CD8⁺、CD4⁺/CD8⁺）、生存质量（QLQ-C30评分、KPS评分）以及不良反应、随访1年的生存情况。结果 治疗后,治疗组客观缓解率（42.00%）、疾病控制率（74.00%）明显高于对照组（22.00%、52.00%）,组间比较差异有显著性（P＜0.05）。治疗后,两组QLQ-C30评分、KPS评分均显著升高（P＜0.05）,治疗组QLQ-C30评分、KPS评分显著高于对照组（P＜0.05）。治疗后,对照组CD3⁺、CD4⁺、CD4⁺/CD8⁺显著降低,CD8⁺显著升高（P＜0.05）;治疗组CD3⁺、CD4⁺、CD4⁺/CD8⁺明显高于对照组,CD8⁺低于对照组（P＜0.05）。治疗后,两组血清SCC-Ag、CYFRA21-1、CEA、CA125水平均显著降低（P＜0.05）,治疗组血清SCC-Ag、CYFRA21-1、CEA、CA125水平显著低于对照组（P＜0.05）。治疗组不良反应发生率为28.00%,明显低于对照组不良反应发生率48.00%,组间比较差异有显著性（P＜0.05）。随访1年后,治疗组中位生存期、肿瘤无进展时间均明显长于对照组（P＜0.05）。结论 安替可胶囊联合TP方案治疗晚期食管鳞癌能增强治疗效果,提高生活质量,减轻免疫功能抑制,降低肿瘤标志物水平,有助于延长患者生存期。     

CD4+CD25+调节性T细胞在多种类型疫苗中作用的研究进展

CD4⁺CD25⁺ 调节性T细胞具有免疫抑制作用。CD4⁺CD25⁺ 调节性T细胞可由多种类型肿瘤、病原体诱导产生。一方面抑制炎症,防止机体组织损伤;另一方面阻碍机体清除肿瘤细胞和病原体,有利于肿瘤和病原体逃避宿主免疫攻击。使用抗体阻断CD4⁺CD25⁺ 调节性T细胞或干扰其抑制功能则利于机体清除肿瘤和病原体。同样,多种类型疫苗可诱导宿主产生CD4⁺CD25⁺ 调节性T细胞,因而抑制了疫苗引起的免疫反应。使用抗体如抗CD25单克隆抗体等封闭CD4⁺CD25⁺ 调节性T细胞或者抑制其分泌的细胞因子如白细胞介素-10(IL-10)、转化生长因子-β(TGF-β),可增强疫苗的免疫保护效果,从而为寻找更有效的疫苗提供新的思路。     

东阿阿胶对体外培养的癌症放疗病人外周血淋巴细胞的影响

目的观察东阿阿胶对体外培养的癌症放疗病人外周血淋巴细胞的影响。方法SD大鼠东阿阿胶灌胃给药3d后取血制备含药血清;取放疗病人外周血,经淋巴细胞分离液分离出淋巴细胞,接种于96孔培养板,东阿阿胶含药血清按分组剂量加入培养孔中,阳性对照为胸腺肽,37℃,5%CO₂培养一定时间后,上流式细胞仪测定增殖率、T淋巴细胞活化抗原的表达、淋巴细胞表型及Th1/Th2细胞的比例。结果与对照组相比,不同剂量含东阿阿胶血清均能显著促进丝裂原诱导的淋巴细胞增殖,促进淋巴细胞活化,提高CD3⁺(T细胞)、CD3^-CD56⁺CD16⁺(NK细胞)的比例和CD3⁺CD4⁺/CD3⁺CD8⁺比值,增加Th1,降低Th2。结论东阿阿胶能解除或减轻肿瘤和放疗对免疫系统产生的抑制作用,有助于免疫细胞对肿瘤的应答。     

槐杞黄颗粒联合艾曲泊帕乙醇胺治疗儿童难治性免疫性血小板减少症的临床研究

目的 探讨槐杞黄颗粒联合艾曲泊帕乙醇胺片治疗儿童难治性免疫性血小板减少症的临床效果。方法 选取2020年1月—2022年7月河北省儿童医院收治的60例儿童难治性免疫性血小板减少症患儿，将60例患儿用随机数字表法分为对照组（30例）和治疗组（30例）。对照组口服艾曲泊帕乙醇胺片，初始剂量25 mg/d，随后根据血小板计数（PLT）调整剂量。治疗组在对照组基础上开水冲服槐杞黄颗粒，1袋/次，2次/d。两组均治疗6个月。比较两组的临床疗效、PLT和免疫功能。结果 治疗后，治疗组总有效率显著高于对照组（P＜0.05）。治疗后，两组PLT较治疗前均显著升高（P＜0.05），且治疗组的PLT高于对照组（P＜0.05）。治疗后，两组CD3⁺、CD4⁺、CD4⁺/CD8⁺水平均明显升高，CD8⁺明显降低（P＜0.05）；治疗后，治疗组CD3⁺、CD4⁺、CD4⁺/CD8⁺水平均高于对照组，CD8⁺低于对照组（P＜0.05）。结论 槐杞黄颗粒联合艾曲泊帕乙醇胺片治疗儿童难治性免疫性血小板减少症具有较好临床疗效，能够在短期内快速提升患儿PLT水平，增强免疫功能。     

CD8阳性T细胞亚群在肺癌外周血的检测及分析

目的 检测肺癌患者外周血清中CD8⁺T细胞亚群CD28⁺及CD57⁺的表达程度,探讨其临床意义。 方法 合肥市第二人民医院经细胞学或病理学诊断为肺癌的初次治疗患者30例, TNM分期(UICC,第7版)Ⅲ期12例,Ⅳ期18例。病理类型腺癌15例,鳞癌8例,小细胞肺癌7例。流式细胞仪分别检测肺癌患者组治疗前后及健康对照组人群的血清中CD8⁺T细胞CD28⁺和CD57⁺的表达水平,分析该表达水平变化及与肺癌临床分期和病理学类型之间的关系。 结果 肺癌患者治疗前血清中CD28⁺T细胞亚群比例为(12.34±3.72)%,CD57⁺ T细胞亚群比例为(19.53±5.26)%。而健康对照组血清中CD28⁺T细胞亚群比例为(23.53±4.15)%,CD57⁺ T细胞亚群比例为(11.37±2.73)%,差异有统计学意义(P<0.05),该类指标与肿瘤病理类型无关,而随着不同临床分期增加,CD8⁺CD57⁺T细胞未见差异,而CD8⁺CD28⁺T细胞表达差异有统计学意义(P<0.05)。经两周期化疗后,缓解组(完全缓解+部分缓解)患者血清中CD28⁺、CD57⁺T细胞亚群比与健康对照组患者相比,差异无统计学意义(P>0.05),而未缓解组(稳定+进展)患者的CD28⁺、CD57⁺T细胞亚群比例分别为(10.62±2.74)%、(20.45±4.36)%.与健康对照组差异有统计学意义(P<0.05)。 结论 肺癌患者血清中CD8⁺CD28⁺T细胞表达较正常人群明显减低,而CD8⁺CD57⁺T细胞表达较正常人群明显升高,联合该两种T细胞亚群检测不仅可以了解肺癌患者免疫状况,同时可以评估肺癌患者预后,有一定临床应用价值。     

纳武利尤单抗联合安罗替尼治疗晚期非小细胞肺癌的临床研究

目的 探究纳武利尤单抗注射液联合盐酸安罗替尼胶囊治疗晚期非小细胞肺癌的临床疗效。方法 选取2019年1月—2020年1月临汾市中心医院收治的60例晚期非小细胞肺癌患者为研究对象,根据患者治疗方法不同分为对照组（29例）和治疗组（31例）。对照组患者早餐前口服盐酸安罗替尼胶囊,12 mg/次,1次/d,连续服药2周,停药1周。治疗组患者在对照组治疗的基础上静脉输注纳武利尤单抗注射液,3 mg/kg,1次/2周,评估患者耐受性和疗效。两组患者均持续治疗9周。观察两组近期临床疗效,比较治疗前后两组生活质量、T淋巴细胞亚群、血管内皮细胞生长因子（VEGF）水平变化和生存情况。结果 治疗后,治疗组客观缓解率（ORR）、疾病控制率（DCR）均较高于对照组,组间比较差异具有显著差异（P<0.05）。治疗后,两组患者CD3⁺、CD4⁺、CD4⁺/CD8⁺均明显升高,CD8⁺、VEGF均明显降低（P<0.05）;治疗组CD3⁺、CD4⁺、CD4⁺/CD8⁺均明显高于对照组,CD8⁺、VEGF均明显低于对照组（P<0.05）。治疗后2、4、6个月,两组EORTC QLQ-C30总评分均明显降低（P<0.05）,且治疗组EORTC QLQ-C30总评分明显低于同期对照组（P<0.05）。治疗后,治疗组中位无进展生存期（PFS）、总生存期（OS）较对照组明显增长（P<0.05）。结论 纳武利尤单抗注射液联合盐酸安罗替尼胶囊治疗晚期非小细胞肺癌具有较好的临床疗效,可改善患者的生活质量,调节患者免疫功能,降低VEGF水平,且不增加不良反应。     

重组人生长激素联合头孢曲松治疗新生儿败血症的临床研究

目的 探讨注射用重组人生长激素联合注射用头孢曲松钠治疗患儿新生儿败血症的临床疗效。方法 选取2018年5月—2021年1月许昌市中心医院收治的86例新生儿败血症患儿作为研究对象,根据随机数字表法将86例患儿分为对照组和治疗组,每组各43例。对照组患儿微泵静脉滴注注射用头孢曲松钠20 mg/kg,1次/d。治疗组在对照组治疗的基础上腹部肌注注射用重组人生长激素,剂量0.1 IU/kg,1次/2 d。两组患儿连续治疗8 d。观察两组患儿的临床疗效,比较两组患儿症状体征改善时间,以及血清中C反应蛋白（CRP）、白细胞介素-6（IL-6）、降钙素原（PCT）、CD4⁺/CD16⁺、CD3⁺、CD4⁺水平。结果 治疗后,治疗组的总有效率（95.35%）高于对照组（81.40%）,组间差异有显著性（P<0.05）。治疗后,治疗组的体温恢复时间、拒奶消失时间、住院时间均明显短于对照组（P<0.05）。治疗后,两组的血清CRP、IL-6、PCT水平明显降低（P<0.05）;且治疗组的血清CRP、IL-6、PCT水平低于对照组（P<0.05）。治疗后,治疗组的CD4⁺/CD16⁺较治疗前显著降低,CD3⁺、CD4⁺较治疗前显著升高（P<0.05）;治疗组患者的CD4⁺/CD16⁺明显低于对照组,CD3⁺、CD4⁺高于对照组（P<0.05）。结论 注射用重组人生长激素联合注射用头孢曲松钠可提高新生儿败血症的疗效,有助于改善临床症状,降低炎症反应,改善患儿的免疫功能,药物安全性良好。     

基于戊肝病毒的嵌合病毒样颗粒对人乳头瘤病毒16型肿瘤免疫治疗作用的研究

目的 研究基于戊肝病毒(hepatitis E virus,HEV)的嵌合病毒样颗粒(virus-like particles,VLPs)对人乳头瘤病毒16型(human papillomavirus type 16,HPV 16)肿瘤免疫治疗作用。方法 将HPV 16 E7插入HEV的p239蛋白形成重组嵌合蛋白p239-HPV16 E7。所构建的重组蛋白经大肠杆菌表达、纯化、复性后,通过电镜和动态光散射对所得蛋白颗粒大小形态进行表征。将蛋白颗粒免疫C57B/L小鼠,通过流式细胞技术与酶联免疫斑点免疫试验检测脾淋巴细胞特异性免疫细胞分化情况;并且利用TC-1肿瘤细胞在C57B/L小鼠中构建肿瘤模型,以此评价蛋白颗粒在小鼠体内的抗肿瘤免疫效果。结果 体外复性后的嵌合蛋白在电镜下观察到颗粒结构,粒径大小为22.80 nm。所得蛋白颗粒在C57B/L小鼠体内诱导产生良好的特异性细胞免疫反应。与对照组相比,试验组脾淋巴细胞的CD3⁺/CD4⁺、CD3⁺/CD8⁺比例均有明显差异(P＜0.05),且分泌IFN-γ干扰素的效应T细胞显著增加。同时,所得蛋白颗粒能有效抑制TC-1荷瘤小鼠体内肿瘤细胞的生长,在实验周期内小鼠未出现死亡,而对照组小鼠体内肿瘤快速生长,且6周后全部死亡。结论 原核表达的嵌合蛋白p239-HPV16 E7形成病毒样颗粒并有效诱导针对HPV 16的抗肿瘤免疫。     

香菇多糖对新辅助化疗后乳腺癌患者免疫功能及淋巴细胞的影响

目的 探讨香菇多糖对新辅助化疗后乳腺癌患者免疫功能及淋巴细胞的影响。 方法 自2015年1月至2016年10月,前瞻性收集内蒙古医科大学附属医院收治的接受新辅助化疗的乳腺癌患者88例,采用随机对照的方式将其分为观察组(44例)和对照组(44例)。两组患者治疗方法相同,观察组联合应用香菇多糖,所有患者均新辅助化疗后手术切除肿瘤组织并留取肿瘤组织标本,观察肿瘤组织及外周血CD4⁺T细胞、CD8⁺T细胞、CD4⁺/CD8⁺比例以及血清白细胞介素-6(IL-6)、白细胞介素-10(IL-10)、转化生长因子-β1(TGF-β1)浓度。 结果 治疗后,观察组肿瘤组织微环境CD4⁺T细胞明显低于对照组(21.56%±5.08% 比 23.95%±5.17%,t=2.187,P=0.031);CD8⁺T细胞高于对照组(29.52%±3.51% 比 27.47%±3.68%,t=2.673,P=0.009);CD4⁺/CD8⁺T细胞比例低于对照组(0.72±0.12比 0.86±0.14,t=5.036,P=0.000)。外周血CD4⁺T细胞水平明显增加(28.57%±4.32% 比 26.23%±4.12%,t=2.600,P=0.011);CD4⁺/CD8⁺T细胞比例明显增加(0.84±0.15比 0.76±0.13,t=2.673,P=0.009)。外周血IL-6浓度明显增高[(14.56±4.79) 比(11.45±4.48) ng·L-1,t=3.145,P=0.002)];IL-10浓度明显降低[(11.34±3.37) 比(13.46±3.41) ng·L-1,t=2.933,P=0.004)];TGF-β1浓度明显降低[(15.14±4.69) 比 (17.67±4.53) μg·L-1,t=2.290,P=0.024)]。结论 香菇多糖有助于提高新辅助化疗后乳腺癌患者免疫功能,改善肿瘤组织微环境中免疫状态。     

Inhibition of Na+-pump enhances carbachol-induced influx of 45Ca2+ and secretion of catecholamines by elevation of cellular accumulation of 22Na+ in cultured bovine adrenal medullary cells

Summary In bovine adrenal medullary cells, we reported that ²²Na⁺ influx via nicotinic receptor-associated Na⁺ channels is involved in ⁴⁵Ca²⁺ influx, a requisite for initiating the secretion of catecholamines (Wada et al. 1984, 1985b).In the present study, we investigated whether the inhibition of Na⁺-pump modulates carbachol-induced ²²Na⁺ influx, ⁴⁵Ca²⁺ influx and catecholamine secretion in cultured bovine adrenal medullary cells. We also measured ⁸⁶Rb⁺ uptake by the cells to estimate the activity of Na⁺, K⁺-ATPase. (1) Ouabain and extracellular K⁺ deprivation remarkably potentiated carbachol-induced ²²Na⁺ influx, ⁴⁵Ca²⁺ influx and catecholamine secretion; this potentiation of carbachol-induced ⁴⁵Ca²⁺ influx and catecholamine secretion was not observed in Na⁺ free medium. (2) Carbachol increased the uptake of ⁸⁶Rb⁺; this increase was inhibited by hexamethonium and d-tubocurarine. In Na⁺ free medium, carbachol failed to increase ⁸⁶Rb⁺ uptake. (3) Ouabain inhibited carbachol-induced ⁸⁶Rb⁺ uptake in a concentration-dependent manner, as it increased the accumulation of cellular ²²Na⁺. These results suggest that Na⁺ influx via nicotinic receptor-associated Na⁺ channels increases the activity of Na⁺, K⁺-ATPase and the inhibition of Na⁺, K⁺-ATPase augmented carbachol-induced Ca²⁺ influx and catecholamine secretion by potentiating cellular accumulation of Na⁺. It seems that nicotinic receptor-associated Na⁺ channels and Na⁺, K⁺-ATPase, both modulate the influx of Ca²⁺ and secretion of catecholamines by accomodating cellular concentration of Na⁺.     

Radiopharmaceutical chemistry for positron emission tomography

Molecular imaging is an emerging technology that allows the visualization of interactions between molecular probes and biological targets. Molecules that either direct or are subject to homeostatic controls in biological systems could be labeled with the appropriate radioisotopes for the quantitative measurement of selected molecular interactions during normal tissue homeostasis and again after perturbations of the normal state. In particular, positron emission tomography (PET) offers picomolar sensitivity and is a fully translational technique that requires specific probes radiolabeled with a usually short-lived positron-emitting radionuclide. PET has provided the capability of measuring biological processes at the molecular and metabolic levels in vivo by the detection of the gamma rays formed as a result of the annihilation of the positrons emitted. Despite the great wealth of information that such probes can provide, the potential of PET strongly depends on the availability of suitable PET radiotracers. However, the development of new imaging probes for PET is far from trivial and radiochemistry is a major limiting factor for the field of PET. In this review, we provided an overview of the most common chemical approaches for the synthesis of PET-labeled molecules and highlighted the most recent developments and trends. The discussed PET radionuclides include ¹¹C (t_1/2 = 20.4 min), ¹³N (t_1/2 = 9.9 min), ¹⁵O (t_1/2 = 2 min), ⁶⁸Ga (t_1/2 = 68 min), ¹⁸F (t_1/2 = 109.8 min), ⁶⁴Cu (t_1/2 = 12.7 h), and ¹²⁴I (t_1/2 = 4.12 d).     

Some degree of overlap exists between the K+-channels opened by cromakalim and those opened by minoxidil sulphate in rat isolated aorta

Summary The effects of the K⁺ channel opening drugs minoxidil sulphate and cromakalim, on ⁴²K⁺ and ⁸⁶Rb⁺ efflux and on vasorelaxation in rat isolated aorta, were compared. In rat aortic rings precontracted with noradrenaline (100 nmol/l), minoxidil sulphate and cromakalim concentration-dependently inhibited induced tension by up to 90%, with pD₂ values of 7.35±0.1 and 7.17±0.1, respectively. Glibenclamide (300 nmol/l), produced 2200- and 19-fold rightward shifts in the concentration-relaxation curves to minoxidil sulphate and cromakalim, respectively, without an effect on the maximum relaxation.Both minoxidil sulphate and cromakalim increased the efflux of ⁴²K⁺ and ⁸⁶Rb⁺ from aorta in a concentration-dependent manner, with midpoints in the µmol/l range; the maximum efflux induced by minoxidil sulphate being approximately one tenth of that induced by cromakalim. The ratio of stimulated ⁸⁶Rb⁺/⁴²K⁺ efflux increased from 0.22 to 0.48 with increasing cromakalim concentrations, but was approximately constant (0.39) when the minoxidil sulphate concentration was varied. In the presence of minoxidil sulphate, the effects of cromakalim on ⁴²K⁺ and ⁸⁶Rb⁺ efflux were inhibited in a concentration-dependent manner, by up to 60%. In the continuing presence of cromakalim (300 nmol/l), minoxidil sulphate (10 µmol/l)-induced increases in ⁴²K⁺ and ⁸⁶Rb⁺ efflux were inhibited by 45%, whereas conditioning with cromakalim (1 µmol/l) inhibited the ⁸⁶Rb⁺ efflux stimulated by additional superfusion of cromakalim (1 µmol/l) by 85%. Glibenclamide inhibited minoxidil sulphate (10 µmol/l)- and cromakalim (1 µmol/l)-induced increases in ⁴²K⁺ and ⁸⁶Rb⁺ efflux in a concentration-dependent manner with IC₅₀ values of approximately 80 nmol/l.In conclusion, the efflux data suggest that considerable overlap exists between the channels opened by minoxidil sulphate and those opened by cromakalim in rat aorta. Minoxidil sulphate has a weak efficacy as a K⁺ channel opener, and may act to open a homogeneous population of K⁺ channels. In contrast, the actions of cromakalim (1 µmol/l) are associated with large increases in tracer efflux, which are probably mediated via a heterogeneous population of K⁺ channels. However, only a small proprtion of this induced efflux appears to be required for relaxation. The differential inhibition by glibenclamide of the vasorelaxant effects of minoxidil sulphate and cromakalim may result from (a) the partial agonist properties of minoxidil sulphate in opening K⁺ channels and/or (b) additional mechanisms of vasorelaxation, which differ in their sensitivity to glibenclamide. Send offprint requests to U. Quasi at the above address     

Role of Na+ and protein kinase C in angiotensin desensitization and tachyphylaxis in the guinea-pig ileum

Summary Simultaneous recordings of the tension and intracellular Ca²⁺ concentration of guinea-pig ileum longitudinal smooth muscle strips, as well as ²⁴Na⁺ and ⁴⁵Ca²⁺ influx measurements in cultured myocytes from the same tissue, were used to investigate the mechanisms underlying angiotensin-induced desensitization and tachyphylaxis. Angiotensin II and [2-lysine]-angiotensin II (Lys²All), incubated for prolonged periods (10 min) with muscle strips, induced fading of the contractile response (desensitization) and reappearance of the intracellular Ca²⁺ concentration oscillations, which were inhibited during the initial increase in cytosolic Ca²⁺. The desensitization was paralleled, in cultured myocytes, by inhibition of the ⁴⁵Ca²⁺ but not of the ²⁴Na⁺ influxes which were initially stimulated by the peptides. On the other hand, repeated administrations of angiotensin II (but not of Lys²All) caused gradual reduction of the contractile response and of the ²⁴Na⁺ influx stimulation evoked by the agonist (tachyphylaxis). Treatment with phorbol 12–13 dibutyrate accelerated the desensitization induced by both angiotensin II and by Lys²All and aggravated the tachyphylaxis to angiotensin II. The results support the hypothesis that activation of protein kinase C is responsible for the desensitization and that tachyphylaxis is due to the slow dissociation of angiotensin II from a postulated Na⁺-dependent regulatory site on the receptor.Correspondence to S.I. Shimuta at the above address     

Distribution of 2, 21,4,41, 5,51-hexaehlorobiphenyl in mice and Chinese Hamsters

The distribution of 2,2¹,4,4¹,5,5¹-hexachlorobiphenyl-¹⁴C was studied in mice and Chinese Hamsters using whole body autoradiography and liquid scintillation counting. The mice exhibited a strong and persistent accumulation of radioactivity in the bronchial mucosa, and this accumulation was not fully developed until about 24 hrs after an intravenous injection. The labelled substance passed to the fetuses of pregnant mice and was also concentrated in the fetal bronchi. Mice pretreated with a large dose of unlabelled PCB per os in peanut oil showed a completely different distribution pattern in the lungs — only traces of label being taken up by the bronchi. Quantitative measurements revealed a concomitant reduction of the total radioactivity retained by the lungs. Except for the lungs, however, no major differences in the distribution pattern were found at the various dose levels. The distribution in the Chinese hamsters equaled approximately that of the mice, but a very weak accumulation of label was observed in the hamster bronchi. The radioactivity in the mouse bronchi was considered as perhaps representing metabolized PCB.     

Decontamination of rat and human skin experimentally contaminated with 99mTc, 201Tl and 131I radionuclides using “Dermadecon” – a skin decontamination kit: an efficacy study

Radioactive skin contamination is one of the most likely risks which occurs after accidental or occupational radiological accidents apart from internal contamination. In such cases where the radioactive contamination has occurred, the person who is contaminated should be decontaminated as early as possible to reduce the damaging health effects of radiation. In the present study, the decontamination efficiency of a developed skin decontamination kit “dermadecon” has been evaluated in animal models and human subjects using gamma scintigraphy. Decontamination efficiency (percentage of the radioactive contaminant removed) was calculated for each radioactive isotope of the study and compared with control where general washing procedure was followed using liquid and soap. The effectiveness of the kit was calculated in animal model with respect to ^99mTc-sodium-pertechnetate (^99mTcO^4?), ²⁰¹TlCl and ¹³¹I and was found 92.84?±?4.9%, 91.18?±?3.23% and 94.67?±?2.92%, respectively. Whereas, in case of human skin, the decontamination efficiency for ^99mTcO^4? was observed to be 95.00?±?3.21%. On the basis of findings from the study, it can be concluded that the decontamination agents of the used skin decontamination kit are effective for removal of localized radioactive contaminants from skin, as compared with normal decontamination using soap and water.     

Effects of propylthiouracil and methylthiouracil on cyclic AMP and ion movements in rat pancreatic islets

Summary Propylthiouracil and methylthiouracil have been shown to potentiate glucose-induced insulin secretion from rat pancreatic islets: the effect of methylthiouracil being less pronounced than that of propylthiouracil. In this study the effects of these substances on cAMP levels, ⁸⁶Rb⁺ efflux, ⁴⁵Ca²⁺ net uptake, and ⁴⁵Ca²⁺ efflux were tested in isolated rat islets in order to obtain information on their possible mechanism of action. Propylthiouracil and to a lesser extent methylthiouracil increased islet cyclic AMP in a concentration-related manner. Maximum increases at the highest concentrations tested were 261% and 190% respectively. In the presence of 3 mM glucose propylthiouracil and methylthiouracil led to a decrease in the ⁸⁶Rb efflux rate. With 5.6 mM glucose, both thiourea derivatives produced an increase in the ⁸⁶Rb⁺ efflux rate which was independent of the presence or absence of calcium in the medium. Propylthiouracil and methylthiouracil augmented the ⁴⁵Ca²⁺ efflux rate in the presence as well as in the absence of external calcium at various glucose concentrations. Propylthiouracil did not change, and methylthiouracil only slightly augmented, ⁴⁵Ca²⁺ net uptake into the isolated islets. It is suggested that the synergistic effect of propylthiouracil and methylthiouracil on glucose-induced insulin release is at least in part due to an increase in islet cAMP levels. Whether the two substances have additional direct effects on ionic fluxes which contribute to their insulinotropic action or whether the observed changes in ion movements are secondary to the elevation of cAMP levels remains to be unclear and needs further investigation. Send offprint requests to H. P. T. Ammon at the above address     

Comparison of the effluxes of 42K+ and 86Rb+ elicited by cromakalim (BRL 34915) in tonic and phasic vascular tissue

Summary The cromakalim-induced effluxes of ⁴²K⁺ and ⁸⁶Rb⁺ were compared in rat aortic segments and in guinea-pig portal vein. In both vessels, low concentrations of cromakalim (0.1 M) increased the permeability to ⁸⁶Rb⁺ 3–4 times less than that to ⁴²K⁺; at 10 M the difference was about a factor of 1.3–2. In rat aorta, the threshold concentration of cromakalim for ⁴²K⁺ efflux was 0.03 M; with ⁸⁶Rb⁺ as the tracer ion it was 0.1 M. At similar concentrations, cromakalim relaxed the tension of aortic segments precontracted with 23 mM KCl (IC₅₀ = 0.06 ± 0.01 M). However, no concomitant increase in ⁴²K⁺ or ⁸⁶Rb⁺ efflux could be detected from this stimulated preparation at these concentrations. In guinea-pig portal vein, ⁴²K⁺ efflux measurements were performed in the presence and absence of the dihydropyridine Ca²⁺ entry blocker PN 200-110 (isradipine) yielding comparable results. In the presence of PN 200-110, where spontaneous activity and the K⁺ efflux associated with it were abolished, the threshold concentration of cromakalim for ⁴²K⁺ efflux was 0.02 M as compared to 0.06 M for ⁸⁶Rb⁺ efflux. In the absence of PN 200-110, spontaneous activity of the portal vein was inhibited by 70% and 90% at these concentrations. In double isotope experiments, the K⁺ channel inhibitor tetraethylammonium did not discriminate between the effluxes of ⁴²K⁺ and ⁸⁶Rb⁺ stimulated by cromakalim.It is concluded that in the two vascular tissues examined, cromakalim increased the permeability to ⁴²K⁺ more than to ⁸⁶Rb⁺, the difference being more marked at low cromakalim concentrations. The use of ⁴²K⁺ as the tracer ion narrows the apparent gap between the concentrations of cromakalim which elicit vasorelaxant effects and those which induce an observable increase in K⁺ permeability; however a significant difference persists.Part of the data was presented at the Winter Meeting of the British Pharmacological Society London 1988 [Br J Pharmacol 93 (1988) p 19] Send offprint requests to U. Quasi at the above address     

On the mechanism of action of phenylephrine in rat atrial heart muscle

Both in rat left atrial heart and in aortic smooth muscle preparations, phenylephrine (PE) caused a concentration-dependent increase in force of contraction (F_c) in the presence of atenolol (10 mol/l), which was antagonized by phentolamine, prazosin and WB 4101 in a competitive manner. The pA₂ values of the antagonists in the cardiac tissue were 10–20fold lower than those in the rat thoracic aorta. In the spontaneously beating right atrium, PE exerted a positive chronotropic action, which was not significantly antagonized by phentolamine or prazosin. It is therefore assumed that the effects of phenylephrine in the left atrium and in the aorta are mediated by different subtypes of ₁-adrenoceptors, whereas the effects in the sino-atrial node are probably unrelated to ₁-adrenoceptors. To further elucidate the mechanisms of the positive inotropic effect of PE, action potential configuration and ⁴⁵Ca²⁺ fluxes were monitored in the rat left atrium. The increase in F_c by PE was associated with an increase in action potential duration (APD) and a reduction in resting membrane potential (RP). In the presence of (–)-devapamil (13888), the effects of PE on APD and RP persisted, whereas the increase in F_c was antagonized in a non-competitive manner. Forskolin (300 nmol/l) enhanced the positive inotropic effect of PE. PE exerted a significant increase in ⁴⁵CA²⁺ uptake in beating preparations, which was abolished in the presence of (–)13888 (1 mol/l). In addition to the PE-induced increase in ⁴⁵Ca²⁺ uptake, a decrease in ⁴⁵Ca²⁺ efflux was observed. Similarly, depolarization of the membrane by raising [K⁺]_o to 85 mmol/l revealed an increase in ⁴⁵Ca²⁺ uptake and a decrease in ⁴⁵Ca²⁺ efflux. The latter observations support the view that the membrane potential strongly determines the movement of ⁴⁵Ca²⁺ across the membrane. It is assumed that the ₁-adrenoceptor-mediated changes in APD and RP may enhance F_c, first, by increasing net Ca²⁺ entry from the extracellular space through voltage-dependent Ca²⁺ channels and, second, by decreasing Ca²⁺ efflux possibly via the Na ⁺/Ca²⁺ exchange mechanism.     

Molecular and functional characterization of the human platelet Na(+) /Ca(2+) exchangers

BACKGROUND AND PURPOSE The Na(+) /Ca(2+) exchanger is a bi-directional transporter that plays an important role in maintaining the concentration of cytosolic Ca(2+) ([Ca(2+) ](i) ) of quiescent platelets and increasing it during activation with some, but not all, agonists. There are two classes of Na(+) /Ca(2+) exchangers: K(+) -independent Na(+) /Ca(2+) exchanger (NCX) and K(+) -dependent Na(+) /Ca(2+) exchanger (NCKX). Platelets have previously been shown to express NCKX1. However, initial studies from our laboratory suggest that NCX may also play a role in platelet activation. The objective of this study was to determine if the human platelet expresses functional NCXs. EXPERIMENTAL APPROACH RT-PCR, DNA sequencing and Western blot analysis were utilized to characterize the human platelet Na(+) /Ca(2+) exchangers. Their function during quiescence and collagen-induced activation was determined by measuring [Ca(2+) ](i) with calcium-green/fura-red in response to: changes in the Na(+) and K(+) gradient, NCX pharmacological inhibitors (CBDMB, KB-R7943 and SEA0400) and antibodies specific to extracellular epitopes of the exchangers. KEY RESULTS Human platelets express NCX1.3, NCX3.2 and NCX3.4. The NCXs operate in the Ca(2+) efflux mode in resting platelets and also during their activation with thrombin but not collagen. Collagen-induced increase in [Ca(2+) ](i) was reduced with the pharmacological inhibitors of NCX (CBDMB, KB-R7943 or SEA0400), anti-NCX1 and anti-NCX3. In contrast, anti-NCKX1 enhanced the collagen-induced increase in [Ca(2+) ](i) . CONCLUSIONS AND IMPLICATIONS Human platelets express K(+) -independent Na(+) /Ca(2+) exchangers NCX1.3, NCX3.2 and NCX3.4. During collagen activation, NCX1 and NCX3 transiently reverse to promote Ca(2+) influx, whereas NCKX1 continues to operate in the Ca(2+) efflux mode to reduce [Ca(2+) ](i) .