黄芪对脑缺血再灌注后神经细胞凋亡及Bcl-2蛋白表达的影响

目的：探计补气益血中药黄芪对肭缺血再灌注损伤后神经细胞凋亡及Bcl—2蛋白表达的影响。方法：实验于2004-06/11在第四军医大学西京医院中医科实验室进行。取36只SD大鼠随机分为3组，每纰12只。①模型组：以生理盐水10mL／（kg&;#183;d）灌胃，1次/d，7d后线栓法制备大鼠局灶性脑缺血2h再灌注模型，6只在再灌注6h麻醉状态下处死取脑，免疫组织化学法与医学图像分析结合的方法检测Bcl-2蛋白的表达；剩余6只在再灌注24h麻醉状态下处死取脑，TUNEL法检测大鼠脑组织神经细胞凋亡。②黄芪组：以黄芪煎剂6g/（kg&;#183;d）灌胃7d，其余处理同模型组。⑧假手术组：不阻塞大脑中动脉，其余处理同模型组。结果：36只大鼠全部进入结果分析。①TUNEL阳性神经细胞数目：模型组高于假手术组[（49．9&;#177;9.8），（1．6&;#177;0．6）能见野，t=12．05，P〈0．01]，黄芪组低于模型组[（30．2&;#177;2．1）个／视野，t=4．81，P〈0．01]。②Bcl-2阳性细胞数目：模型组显著高于假手术组[（12．5&;#177;1．2），（1．7&;#177;0．6）个／见野，t=19．71，P〈0．01]，黄芪组显著高于模型组[（16．4&;#177;2．2）个倪野，t=3．17，P〈0．011。⑧Bcl—2蛋白平均灰度：模型组明显低于假手术组（182．8&;#177;13．6，205．9&;#177;115，拉3．18，P〈0．01），黄芪组显著低于模型组（160．8&;#177;10．2，t=3．82，P〈0．01）。结论：黄芪通过上调Bcl—2蛋白的表达可抑制缺血再灌注脑组织神经细胞凋亡，对脑缺血再灌注损伤有明显的神经保护作用。     

氯氮平对大鼠局灶性脑缺血再灌注损伤的保护作用

目的：观察氯氮平对局灶性脑缺血再灌注损伤的保护作用，并与尼莫地平进行阳性对照。 方法：实验于1999年在郑州大学医学院药理教研室实验室进行，取Wistar大鼠240只，单纯随机分成缺血再灌注组，氯氮平24，12，6mg／kg组，尼莫地平组和假手术组6组，每组40只。氯氮平24，12，6mg／kg组腹腔注射相应剂量的氯氮平，尼莫地平组腹腔注射0．2mg／kg尼莫地平，缺血再灌注组和假手术组腹腔注射等体积生理盐水，均为1次／d，连续7d。给药7d后除假手术组外其他5组大鼠栓塞法建立大脑中动脉局灶性缺血再灌注模型。测定再灌注2h缺血侧脑组织含水量、丙二醛含量和超氧化物歧化酶活性；流式细胞仪定量分析细胞凋亡率；Fura-2负载，以荧光分光光度计测定细胞内游离钙的变化。 结果：经补充后240只大鼠进入结果分析。①脑组织含水量：缺血再灌注组高于假手术组[（81．62&;#177;0．15）％，（75．81&;#177;0．23）％，P〈0．01]．其他4组均低于缺血再灌注组（P〈0．01）。②丙二醛含量：缺血再灌注组高于假手术组[（10．85&;#177;0．38），（4．07&;#177;0．63）μmol／g，P〈0．01]，其他4组均低于缺血再灌注组（P〈0．01）。③超氧化物歧化酶活性：缺血再灌注组低于假手术组[（82．47&;#177;10．73），（280．15&;#177;10．32）Nu／mg，P〈0．01]，其他4组均高于缺血再灌注组（P〈0．01）。④细胞内游离钙浓度：缺血再灌注组高于假手术组[（574．87&;#177;14．56），（215．76&;#177;10．84）nmol／L，P〈0．01]，其他4组均低于缺血再灌注组（P〈0．01）。⑤细胞凋亡率：假手术组为0，缺血再灌注组为28％，氯氮平6，12，24mg／kg组及尼莫地平组分别为19％，12％，5％，13％。 结论：①6-24mg／kg氯氮平可显著降低细胞内游离钙含量，抑制缺血再灌注诱导的神经细胞凋亡，提示氯氮平对缺血再灌注所致神经细胞损伤的保护作用可能与其钙拮抗以及抗脂质过氧化有关。②氯氮平的神经保护作用与尼莫地平相似。     

雌激素对沙土鼠脑缺血再灌注后脑海马CA1区细胞凋亡的影响

目的：应用单因素设计观察雌激素对去卵巢沙土鼠脑缺血再灌注后脑海马CAI区细胞凋亡的影响。方法：实验于2004-10／2005—01在菏泽市立医院中心实验室完成，将45只雌性沙土鼠随机分为假手术组，卵巢切除纰和雌二醇组3组，每组15只。①预处理：卵巢切除组和雌二醇住实验前2周切除双侧卵巢，假手术组手术但不切除卵巢。雌二醇组自切除卵巢次日起，每天腹腔注射雌二醇（0．1mg／kg），连续2周；其他两组每日腹腔注射0．5mL的生理盐水。②模型制备：3组均采用舣侧颈动脉夹闭法制备脑缺血再灌注模型。⑧观察指标：所有动物造模后3d麻醉状态下处死取脑，测定脑组织匀浆中超氧化物歧化酶及丙二醛水平，TdT介导的原位末端标记法计量分析。结果：45只沙土鼠全部进入结果分析。①脑海马CA1区细胞凋亡密度：卵巢切除组高于假手术组和雌二醇组[（67，70&;#177;5，98），（43．46&;#177;4．66），（45，13&;#177;3盘7）个／40&;#215;10视野，F=21.32，P〈0．051。②脑组织中丙二醛浓度：卵巢切除组高于假手术组和雌二醇组[（4．67&;#177;0．56），（2，74&;#177;0．25），（2．77&;#177;0．31）μmol／L，F=23，56,P〈0．051。㈤超氧化物歧化酶活性：卵巢切除组低于假手术组和雌二醇组[（38．12&;#177;4．17），（56，22&;#177;7．80），（54．78&;#177;6．90）NU／mL，F=19．75，P〈0．05]。假手术组与雌二醇组比较上述指标均无差异（P〉0．05）。结论：雌激素可以减少自由基损伤时脑神经元中的丙二醛含量，提高超氧化物歧化酶活性，减轻沙土鼠脑缺血再灌注后脑海马CA1区神经细胞的凋亡，对沙土鼠脑缺血再灌注损伤具有保护作用。     

大鼠脑缺血再灌注后细胞间黏附分子1表达与白细胞浸润的关系及吲哚美辛的干预效应

目的：观察脑缺血2h再灌注不同时间点脑组织细胞间黏附分子1的表达与白细胞浸润的关系，并观察吲哚美辛对细胞间黏附分子1表达及白细胞浸润的影响。 方法：实验于2004-09／2005-03在大连医科大学附属第二医院中心实验室完成。取35只雄性SD大鼠随机分为假手术组5只、对照组25只，吲哚美辛组5只，对照组又分为缺血2h再灌注2，12，24，48．72h 5个亚组，每个亚组5只。①造模：采用线栓法制作大鼠大脑中动脉阻断模型，阻断大鼠大脑中动脉血流2h之后进行再灌注。②给药：吲哚美辛组在再灌注24h时灌胃给予吲哚美辛（按10mg／kg，溶于2mL生理盐水中），对照组中的再灌注24h亚组给予等容生理盐水。③观察指标：经免疫组化和苏木精-伊红染色，测定细胞间黏附分子1表达阳性微血管数和白细胞计数。 结果：35只大鼠均进入结果分析。①在脑缺血再灌注早期坏死区周围微血管内皮细胞表达细胞间黏附分子1即开始增多[再灌注2h：（15．94&;#177;1．90）个／视野，再灌注12h：（30．73&;#177;3．01）个／视野]，并于24h达高峰[（37．86&;#177;2．21）个／视野]，各对照亚组与假手术组[（0．68&;#177;0.69）个／视野]比较差异有显著性意义（P〈0．01），且各亚组间比较差异有显著性意义（P〈0．01）。②在脑缺血再灌注早期坏死区周围白细胞浸润即开始增多[再灌注2h：（2．30&;#177;0．91）个／视野，再灌注12h：（9．99&;#177;1．40）个／视野]，并于24h达高峰[（22．11&;#177;1．71）个／视野]，各对照组亚组与假手术组比较有显著性差异（P〈0．01），且各亚组两两比较组间差异有显著性意义（P〈0．01）。③细胞间黏附分子1表达与白细胞浸润的相关性分析表明两者之间呈正相关（r=-0．731，P〈0．01）。④吲哚美辛组细胞同黏附分子1表达及白细胞浸润计数[（16．01&;#177;11．43）个／视野，（10．55&;#177;2．64）个／视野1均低于再灌注24h亚组（P〈0．01）。 结论：脑缺血再灌注后细胞问黏附分子1可介导白细胞与内皮细胞的黏附；吲哚美辛可降低脑缺血再灌注后细胞间黏附分子1的表达和白细胞的浸润，对脑缺血再灌注损伤具有保护作用。     

神经生长因子和血管内皮生长因子联合应用对兔局灶性脑缺血再灌注损伤神经元的保护时间窗

目的：观察神经生长因子和血管内皮生长因子对兔局灶性脑缺血再灌注损伤的神经元的保护作用，以及发挥作用的有效时间窗。 方法：实验于2005-05／08在河北医科大学第二医院神经分子影像医学和神经病学实验室进行。34只雄性4．5～5月龄新西兰白兔随机数字表法分为假手术组（n=6）、生理盐水组（n=8），再灌注3h因子治疗组（n=10）和再灌注6h因子治疗组（n=10）。采用兔大脑中动脉阻断局灶性脑缺血再灌注模型，假手术组线栓插入的深度不同。因子治疗组在缺血2h再灌注损伤后3h和6h应用微量进样器将2．5μg／L血管内皮生长因子16550μL和神经生长因子400AU（相当于16μg／L）立体定向导入梗死灶周，生理盐水组则注入同等剂量的生理盐水，于再灌注72h，应用MR影像学、红四氮唑染色和流式细胞术评价各组动物脑梗死体积、灶周缺血半暗带细胞凋亡率、表观弥散系数值比率及半胱氨酸蛋白酶3活性表达。在大脑中动脉阻塞2h再灌注后24，72h，采用Purdy评分标准行神经功能缺损评分。总得分最低为2分，表示无神经功能缺陷；总得分最高为11分，表示动物意识丧失或死亡。 结果：在实验过程中，无动物死亡，均进入结果分析。①缺血2h再灌注72h，MR影像测得梗死灶主要限于左侧大脑中动脉供血区的皮质和皮质下白质和部分尾壳核。再灌注3h因子治疗组、再灌注6h因子治疗组脑梗死百分率分别较生理盐水组下降44．0％和33．3％。②缺血2h再灌注72h的再灌注3h因子治疗组、再灌注6h因子治疗组神经功能缺损评分分别较生理盐水组明显减少，差异有显著性意义[（6．4&;#177;0．5），（4．8&;#177;0．8），（5.4&;#177;0.5），P〈0.01）；[（2．8&;#177;0．4），（3．2&;#177;0．8），（4．6&;#177;0．5），P〈0．01]。③再灌注3h因子治疗组、再灌注6h因子治疗组脑组织含水量与生理盐水组相比明显减少，差异均有显著性意义[（79．2&;#177;0．5）％，（79．9&;#177;0．6）％，（81．8&;#177;0．3）％，0．01]。④缺血2h再灌注72h的再灌注3h因子治疗组、再灌注6h因子治疗组灶周皮质区梗死灶周区表观弥散系数值与生理盐水组相比明显升高，差异有显著性意义[（89&;#177;3）％，（83&;#177;3）％，（74&;#177;4）％，P〈0．01]。这两组灶周皮质凋亡率及半胱氨酸蛋白酶3活性表达与生理盐水组相比则明显降低，差异均有显著性[（10．4&;#177;0．7）％（15．5&;#177;1．2）％（20．2&;#177;1．3）％，P〈0．01]；[（17．4&;#177;1．3），（26．1&;#177;1．0），（54．1&;#177;6．9），P〈0．01]。结论：联合神经生长因子和血管内皮生长因子治疗脑缺血再灌注损伤具有明显的神经元护作用，有效时间窗最少是再灌注后6h。     

高血糖状态下大鼠脑缺血再灌注后不同时限点细胞间黏附分子1及肿瘤坏死因子α表达的差异

目的：观察高血糖状态下大鼠脑缺血再灌注后炎症介导因子细胞间黏附分子1以及促炎性细胞因子肿瘤坏死因子α在不同时限点的表达及其差异。方法：实验于2003-07／2004-03在大连医科大学附属第二医院中心实验室完成。36只雄性SD大鼠随机分成3组：正常血糖组16只、高血糖组16只和假手术组4只，其中高血糖组和正常血糖组又分为再灌注2，4，6，24h4个亚组。建立大鼠大脑中动脉缺血再灌注模型，其中高血糖组在阻断大脑中动脉前30 min腹腔注射500g／L葡萄糖溶液（3g／kg），各组大鼠于麻醉状态下取脑组织制备冠状切片，观察脑组织细胞间黏附分子1、肿瘤坏死因子α表达采用免疫组织化学方法。结果：36只大鼠均进入结果分析。①各组大鼠脑组织细胞间黏附分子1的表达：正常血糖组缺血2h再灌注2h可见细胞间黏附分子1表达[（18．13&;#177;2．16）个／视野]，再灌注24h达高峰[（59．50&;#177;2．25）个／视野]。与正常血糖组相比，高血糖组细胞问黏附分子1表达高峰提前至再灌注6h[（76．75&;#177;2．14）个／视野]。在再灌注2，4，6h高血糖组明显高于正常血糖组，再灌注24h时低于正常血糖组（P〈0．01）。②各组大鼠脑组织肿瘤坏死因子α的表达：正常血糖组和高血糖组均在缺血2h再灌注2h时可见肿瘤坏死因子α的表达[（7．81&;#177;1．60）个／视野。（11．65&;#177;1.90）个／视野，P〈0．01]，于再灌注24h达高峰[（26．25&;#177;1．81）个／视野，（35．00&;#177;228）个／视野，P〈0．01]。在同一再灌注时间点明显高于正常血糖组（P〈0．01）。结论：高血糖状态下细胞间黏附分子1及肿瘤坏死因子α均呈高表达，但细胞间黏附分子1的表达与肿瘤坏死因子α的表达具有时间上的差异。     

葡萄籽原花青素对脑缺血再灌注损伤的保护作用

目的：观察不同剂量葡萄籽原花青素对大鼠局灶性脑缺血再灌注损伤的神经保护作用及其作用的不同途径。 方法：实验于2004-10／2005-07在安徽医科大学神经生物实验室完成。取SD大鼠160只随机分成假手术组、模型组和葡萄籽原花青素50，100，200mg／kg组5组，每组32只．①缺血前30min模型组大鼠腹腔注射lmL生理盐水，葡萄籽原花青素50，100，200mg／kg组腹腔注射相应浓度的葡萄籽原花青素液1mL，6h后重复给药一次；假手术组不给药。②采用线栓法制备脑缺血再灌注大鼠模型，假手术组不栓塞动脉。各组随机取8只大鼠在再灌注12h断头处死测脑组织含水量；其余大鼠在再灌注24h断头处死取脑，分别检测脑梗死体积比、缺血侧脑组织超氧化物歧化酶活性和丙二醛含量。 结果：160只大鼠全部进入结果分析。①脑梗死体积比：葡萄籽原花青素100，200mg／kg组显著低于模型组（0．3077&;#177;0．0206，0．2972&;#177;0．0248．0．4594&;#177;0.0399，P〈0．01）。②脑含水量：葡萄籽原花青素50，100，200mg／kg组均低于模型组[（79．97&;#177;0．76）％，（79．63&;#177;0.92）％，（79．67&;#177;0．51）％．（81．41&;#177;1．28）％，P〈0．01]。③超氧化物歧化酶活性：葡萄籽原花青素50，100，200mg／kg组均高于模型组[（64．35&;#177;2．29），（64．52&;#177;2．20），（64．43&;#177;2．38）．（39．72&;#177;6．94）NU／mg，P〈0．01]。④丙二醛含量：葡萄籽原花青素50，100，200mg／kg组均低于模型组[（1．15&;#177;0．07），（1．11&;#177;0．16），（1．01&;#177;0．13）．（1．42&;#177;0．23）μmol／g，P〈0．011。 结论：①葡萄籽原花青素≥100mg/kg时可使局灶性脑缺血大鼠脑梗死体积减小，发挥有效的脑保护作用。②≥50mg／kg时即能增强抗氧化酶活性，减轻脂质过氧化损伤，减轻脑水肿程度。     

脑缺血再灌注损伤大鼠血清细胞因子和内皮素水平变化及小牛血去蛋白注射液的干预作用

目的：观察小牛血去蛋白注射液对脑缺血再灌注损伤大鼠血清内皮素、肿瘤坏死因子α和白细胞介素6的影响。 方法：实验于2004-10在锦州医学院药理教研室进行。取30只SD大鼠随机分为假手术组、模型组和小牛血去蛋白注射液组3组，每组10只。①假手术组和模型组灌胃给予生理盐水2mL／d，小牛血去蛋白注射液组灌胃给予小牛血去蛋白注射液2mL／d，连续5d。（爹给药5d后模型组和小牛血去蛋白注射液组采用右侧颈总动脉结扎法制作不完全性脑缺血60min再灌注模型，假手术组不结扎右侧颈总动脉。③再灌注60min后取血，利用放射免疫技术检测大鼠血清细胞因子肿瘤坏死因子α、白细胞介素6和内皮素水平。 结果：30只大鼠全部进入结果分析。①肿瘤坏死因子α水平：小牛血去蛋白注射液组高于假手术组[（1．08&;#177;0．15），（0．84&;#177;0．08）mg／L，P〈0．05]，但显著低于模型组[（1．32&;#177;0．13）mg／L，P〈0．01]。（爹白细胞介素6水平：小牛血去蛋白注射液组高于假手术组[（117．10&;#177;14．72），（84．60&;#177;9．57）μg／L，P〈0．05]，但显著低于模型组[（140．70&;#177;16．32）μg／L，P〈0．01]。③内皮素水平：小牛血去蛋白注射液组高于假手术组[（166．30&;#177;6．36），（130．50&;#177;3．63）μg／L，P〈0．05]，但显著低于模型组[（171．00&;#177;4．74）μg／L，P〈0．01]。 结论：小牛血去蛋白注射液显著降低脑缺血再灌注大鼠血中肿瘤坏死因子α、白细胞介素6及内皮素水平，保护脑结构。     

促红细胞生成素预处理对肢体缺血再灌注损伤的影响

目的：观察促红细胞生成素预处理对骨骼肌缺血再灌注损伤的影响。 方法：实验于2004—08／2005—01在解放军第二五二医院中心实验室完成。①采用大鼠右后肢缺血再灌注模型，将30只实验大鼠随机分为3组，每组10只。假手术组：仅显露股血管鞘，不做缺血再灌注，经腹腔注射同体积生理盐水；对照组：经腹腔注射同体积生理盐水，持续缺血4h．再灌注1h。促红细胞生成素预处理组（预处理组）：经腹腔注射5000u／kg人重组促红细胞生成素，24h后持续缺血4h，再灌注1h。②测定各组血清磷酸激酶，乳酸脱氢酶丙二醛和腓肠肌^99Tc^m亚甲基二磷酸钠吸收量变化。③电镜观察腓肠肌超微结构变化。 结果：30只大鼠全部进入结果分析。①对照组和预处理组血清磷酸激酶[（121．627&;#177;18．112），（84．417&;#177;14．594）μkat／L]、乳酸脱氢酶[（20．065&;#177;4．676），（13．354&;#177;5．229）μkat/L]明显高于假手术组[（50．247&;#177;16．066），（7．732&;#177;1．256）μkat／L1（P〈0．05）；对照组和预处理组丙二醛[（10．36&;#177;2．65），（6．55．&;#177;2．19）nmol／L]及^99Tc^m亚甲基二磷酸钠吸收量[（16．69&;#177;3．14），（11．66&;#177;3．87）％／（g&;#183;min）]均明显高于假手术组[（3．54&;#177;1．89）nmol／L，（9．12&;#177;1．96）％／（g&;#183;min）（P〈0．05）]。②预处理组各指标与对照组相比显著降低（P〈0．05）。 结论：促红细胞生成素对肢体骨骼肌缺血再灌注损伤具有保护作用。     

大鼠局灶性脑缺血再灌注后脑组织的氧化损伤

目的：通过观察大鼠局灶性脑缺血再灌注后脑组织超氧化物歧化酶活性和丙二醛含量的变化，进一步探讨大鼠局灶性脑缺血再灌注后氧化损伤的病理生理改变。方法：实验于2004-09／2005-01在泸州医学院神经生物学教研室进行。将雄性成年Wistar大鼠60只随机分为2组：假手术组30只和缺血再灌注组30只。每组分3个观察时间点，分别为手术后6，12，24h，每个时间点10只。采用线栓法制成大脑中动脉闭塞模型，假手术组手术过程同缺血再灌注组，但未插栓线，不造成脑缺血。测定手术后不同时点脑组织超氧化物歧化酶活性和丙二醛水平。结果：在实验过程中有6只大鼠死亡，缺血再灌注组有8只大鼠手术后模型评价为0级，被排除实验，随机补充14只大鼠，最终进入结果分析仍为60只大鼠。①缺血再灌注组术后6，12，24h超氧化物歧化酶活性均低于假手术组[（289．72&;#177;10．67），（534．77&;#177;22．67）μkat／L；（330．57&;#177;18．17），（539．11&;#177;11．50）μkat／L；（377．58&;#177;14．67），（550．78&;#177;11．50）μkat／L，P〈0．05]。②缺血再灌注组术后6，12，24h丙二醛水平显著高于假手术组[（15．06&;#177;0．59），（6.78&;#177;0．25）μmoL／L；（13．53&;#177;1．11），（6．78&;#177;0．26）μmol／L；（11．31&;#177;0．97），（6．80&;#177;0．26）μmoL／L，P〈0．05]。结论：脑缺血再灌注后，缺血大鼠脑组织内丙二醛水平升高，超氧化物歧化酶活性降低，说明自由基参与了脑缺血再灌注损伤的病理生理过程。     

Standardization of assays of factor VIII and factor IX

Summary The development of international standards over the last 15–20 years has led to improved interlaboratory agreement on assays of factor VIII and factor IX. In the most recent international collaborative study, the coefficient of variation for one-stage assays (26 laboratories) was 5.6%. However, in quality assurance surveys, carried out in the UK and USA, agreement between laboratories is much less good, with coefficients of variation ranging from 30% to over 50%. Improvements in agreement between clinical laboratories could be obtained by increasing the amount of testing on each sample, especially the number of dilutions, and reducing the number of reagent systems used. A large number of laboratories now use immunodepleted plasmas instead of congenitally deficient plasmas as substrates for one-stage assays. These plasmas may give satisfactory assays, but many of them have not been thoroughly evaluated in comparison with congenitally deficient plasma. In assessment of potency of very high purity (VHP) factor VIII concentrates, some immunodepleted plasmas were found to give lower potencies than hemophilic plasma. This is partly due to the fact that VHP concentrates contain little or no von Willebrand factor (vWF), and most immunodepleted plasmas are also deficient in vWF. In recent collaborative studies, assays of VHP factor VIII concentrate were much more variable, both within and between laboratories, than assays of intermediate purity concentrates. Standardization of these new products will require careful attention to methodological detail. Presented at the ‘2nd International Symposium on Standardization and Quality Control of Coagulation Tests: Implications for the Clinical Laboratory’, Rome, September 28–29, 1989.     

Inhibition of the activation of Hageman factor (factor XII) by platelet factor 4

Platelet factor 4 is a polypeptide constituent of platelet alpha granules that is released during platelet aggregation and inhibits heparin-mediated reactions. Hageman factor (factor XII) is a plasma proenzyme that, when activated by certain negatively charged agents, initiates clotting via the intrinsic pathway of thrombin formation. In earlier studies using crude systems, platelet factor 4 inhibited activation of Hageman factor by dextran sulfate or cerebrosides, but not activation of Hageman factor by kaolin or ellagic acid. In the present study we examined the mechanisms of inhibition by platelet factor 4, using purified reagents. Platelet factor 4 inhibited activation of Hageman factor by ellagic acid, as measured by amidolysis of a synthetic substrate of activated Hageman factor, an effect inhibited by heparin or by an anti-platelet factor 4 antiserum. Coating glass tubes with platelet factor 4 before addition of normal plasma significantly lengthened the partial thromboplastin time of normal plasma. In addition, the clot-promoting properties of kaolin were inhibited by its prior exposure to platelet factor 4. Thus, the inhibitory properties of platelet factor 4 directed against the activation of Hageman factor were confirmed in a purified system. In this purified system, in contrast to earlier studies using crude systems, platelet factor 4 inhibited activation of Hageman factor by glass, ellagic acid, or kaolin.     

A transforming growth factor beta-like immunosuppressive factor in immunoglobulin G-binding factor

Immunoglobulin G-binding factors (IgG-BF), which are produced by cells of the immune system, inhibit antibody production. In this paper, we show that transforming growth factor-beta (TGF-beta) suppresses secondary in vitro anti-sheep red blood cell responses of mouse splenocytes and lipopolysaccharide- or anti-IgM-stimulated mouse B cell responses in a way similar to, and with the same kinetics as, rodent IgG-BF. Moreover, the immunosuppressive activity of IgG-BF was totally neutralized by polyclonal and monoclonal anti-TGF-beta antibodies and it eluted with TGF-beta by gel exclusion chromatography, suggesting that a TGF-beta-like immunosuppressive factor is present in IgG-BF. We also show that TGF-beta behaves as an IgG-BF since it binds to insolubilized IgG, but not to insolubilized F(ab')2 or bovine serum albumin. Altogether, the data support the concept of a biological role for TGF-beta in the IgG-mediated negative feedback of antibody responses.     

Activation of human factor IX (Christmas factor).

Human Factor IX (Christmas factor) is a single-chain plasma glycoprotein (mol wt 57,000) that participates in the middle phase of the intrinsic pathway of blood coagulation. It is present in plasma as a zymogen and is converted to a serine protease, Factor IXabeta, by Factor XIa (activated plasma thromboplastin antecedent) in the presence of calcium ions. In the activation reaction, two internal peptide bonds are hydrolyzed in Factor IX. These cleavages occur at a specific arginyl-alanine peptide bond and a specific arginyl-valine peptide bond. This results in the release of an activation peptide (mol wt approximately equal to 11,000) from the internal region of the precursor molecule and the generation of Factor IXabeta (mol wt approximately equal to 46,000). Factor IXabeta is composed of a light chain (mol wt approximately equal to 18,000) and a heavy chain (mol wt approximately equal to 28,000), and these chains are held together by a disulfide bond(s). The light chain originates from the amino terminal portion of the precursor molecule and has an amino terminal sequence of Tyr-Asn-Ser-Gly-Lys. The heavy chain originates from the carboxyl terminal region of the precursor molecule and contains an amino terminal sequence of Val-Val-Gly-Gly-Glu. The heavy chain of Factor IXabeta also contains the active site sequence of Phe-Cys-Ala-Gly-Phe-His-Glu-Gly-Arg-Asp-Ser-Cys-Gln-Gly-Asp-SER-Gly-Gly-Pro. The active site serine residue is shown in capital letters. Factor IX is also converted to Factor IXaalpha by a protease from Russell's viper venom. This activation reaction, however, occurs in a single step and involves only the cleavage of the internal arginyl-valine peptide bond. Human Factor IXabeta was inhibited by human antithrombin III by the formation of a one-to-one complex of enzyme and inhibitor. In this reaction, the inhibitor was tightly bound to the heavy chain of the enzyme. These data indicate that the mechanism of activation of human Factor IX and its inhibition by antithrombin III is essentially identical to that previously shown for bovine Factor IX.     

The association of factor VIII with von Willebrand factor

Factor VIII (FVIII) and von Willebrand factor (vWF) are plasma glycoproteins that circulate as a tightly associated complex. Because they tend to copurify during procedures designed to isolate the biologic activities associated with them, their identity as distinct entities became unequivocally established only during the past 10 years. Improved procedures for the isolation of FVIII, the deduction of the amino acid sequences of FVIII and vWF by using molecular cloning techniques and by direct sequencing, and the use of a variety of biophysical and immunochemical techniques have enhanced the understanding of the FVIII-vWF association. Each subunit of multimeric vWF potentially can bind a single heterodimeric FVIII molecule, although in vivo most of these binding sites are empty. The binding of FVIII to vWF is primarily, if not exclusively, mediated by the light chain of FVIII to the amino-terminal region of the vWF subunit. Cleavage of a fragment from the amino-terminal region of the FVIII light chain by thrombin results in rapid dissociation of the FVIII-vWF complex, a process that apparently is necessary for development of procoagulant activity. Whether this cleavage is needed for the activation of FVIII in the absence of vWF is controversial. The extracellular association of FVIII with vWF may be necessary for efficient secretion of FVIII from its cell of origin. The thermodynamics, kinetics, and nature of the molecular contacts involved in the interaction have not been studied. The association of FVIII with vWF prolongs the lifetime of FVIII in plasma. Whether the FVIII-vWF interaction has other functional roles, such as restricting the location of procoagulant activity, remains unknown.     

Radioimmunoassay of antihaemophilic factor (factor VIII) antigen

A simple, precise radioimmunoassay for antihaemophilic factor (AHF, factor VIII) antigen has been developed. The technique is based upon a double-antibody solid-phase (DASP) system. This assay may serve as a specific method for differentiation between Von Willebrand's disease and haemophilia A.