Effect of cold storage on platelet glycoprotein Ib and vesiculation

BACKGROUND: During storage of platelet concentrates at 22 degrees C, changes occur in surface glycoproteins, and membranous vesicles appear in the supernatant plasma. The extent of these changes during refrigerated storage is not known. STUDY DESIGN AND METHODS: Membranous microparticles and changes in surface or total glycoprotein Ib (GPIb) were studied in platelet concentrates divided into aliquots stored at either 4 degrees C or 22 degrees C for 5 days. RESULTS: The refrigerated platelets showed greater loss of total GPIb, slightly less binding of monoclonal antibodies to surface GPIb, and reduced aggregation response to ristocetin relative to the paired platelet controls at 22 degrees C. Moreover, the platelets stored at 4 degrees C produced 45-percent more microparticles and 64-percent more platelet factor 3 activity in the supernatant plasma than were produced by the controls. These differences were augmented by warming both 4 degrees C- and 22 degrees C-stored platelets at 37 degrees C for 1 to 4 hours. CONCLUSION: Storage of platelets at 4 degrees C causes increased membrane vesiculation and accelerated loss of GPIb. The magnitude of these differences was small, but it may contribute to marked reductions in platelet survival in circulation.     

Serologic evidence that factor IX inhibitor in the plasma of hemophilia B patients detects factor IX on normal red cells

BACKGROUND: Patients with hemophilia B lack factor IX (F IX). These patients may become alloimmunized after the transfusion of F IX concentrates and may develop F IX inhibitors, which have been characterized as polyclonal IgG4 alloantibodies. Two cases in which F IX inhibitors caused difficulty in compatibility testing and antibody identification were encountered. It was hypothesized that, because F IX is present in normal plasma, it might be adsorbed by red cells in vivo and then be detected during antibody screening tests with serum containing F IX inhibitors. CASE REPORT: Sera from two African American half-brothers with hemophilia B were incompatible with all common and rare red cell phenotypes tested in the anti-human globulin test, but did not react with each other's red cells. The brothers' red cell antibodies were neutralized with both normal plasma and a commercially available F IX concentrate, which indicated that the red cell incompatibility was most probably caused by their F IX inhibitors. Red cells from an unrelated patient with hemophilia B and a very low titer of F IX inhibitor were tested against the half-brothers' sera and did not react. The compatible red cells from one of the half-brothers and the unrelated patient with hemophilia B adsorbed F IX from normal plasma or F IX concentrate after 37 degrees C incubation; this rendered them incompatible with the plasma containing F IX inhibitor from the other half-brother. CONCLUSION: F IX appears to be present on normal red cells and may be detected during compatibility and antibody identification procedures when serum or plasma containing F IX inhibitors is tested.     

贫困县小学生睡眠状况调查

目的:了解贫困地区小学生睡眠状况,探讨提高农村儿童睡眠质量的有效措施。方法:于2005-10在吉林省的国家级贫困县应用澳大利亚悉尼大学儿童睡眠中心临床问卷的中国修订版(内容涉及儿童个人情况、睡眠状况、家庭居住环境,父母睡眠状况、吸烟状况,以及父母职业及受教育程度、家庭成员之间的关系等),采用二阶段整群随机抽样法,对750名小学生的睡眠状况进行调查分析,统计分析近1年内儿童在未患重大疾病时的睡眠状况,包括全天睡眠时间分布状况、睡眠障碍发病率及其相关影响因素,根据美国精神障碍诊断统计手册中儿童睡眠障碍的诊断标准,将每周出现1～3次单一或几种睡眠障碍相关症状,定为存在睡眠问题。结果:共发放问卷750份,回收有效问卷691份,回收率为92.1%。6岁和13岁组人数较少予以去除,实际纳入分析者669名。其中男生300名,女生369名;汉族361名,朝鲜族288名,其他民族20名;7岁组96名,8岁组93名,9岁组94名,10岁组122名,11岁组128名,12岁组136名。①贫困县小学生全天睡眠时间均值为(9.62±1.12)h,汉族小学生全天平均睡眠时间比朝鲜族学生长[(9.75±1.23),(9.48±0.90)h,P<0.01]。各年龄组学生全天睡眠时间差异无统计学意义(F=0.169,P>0.05)。②睡眠障碍总时点发病率为27.40%。低年级组小学生(一～四年级)睡眠障碍发病率高于高年级组(五～六年级)(31.80%,24.15%,P<0.05),男生睡眠障碍发病率高于女生(35.35%,20.95%,P<0.01)。③睡眠障碍症状发病率前5位依次为:睡眠不安(8.4%),睡眠姿势异常(8.3%)、张口呼吸(6.1%),梦呓(5.2%);打鼾(4.3%)。④调查结果经单因素相关分析及多重逐步回归分析显示抚养人睡眠习惯、儿童睡眠姿势异常、母亲管教孩子态度和父亲学历等是影响睡眠时间的主要因素。⑤Logistic回归分析显示,孩子患呼吸系统疾病、父母教育孩子方法、母亲有无睡眠障碍、父母之间关系、儿童体弱多病等是睡眠障碍的主要危险因素。结论:贫困地区儿童睡眠障碍是多因素共同作用的结果;孩子的抚养人应改掉不良的睡眠习惯,为儿童提供良好的生活、睡眠环境;增强儿童身体素质,积极防治呼吸系统疾病,应作为近期降低贫困县小学生睡眠障碍的有效措施。     

Recombinant immunoblot assay reaction patterns and hepatitis C virus RNA in blood donors and non-A, non-B hepatitis patients

To establish the value of the second-generation recombinant immunoblot assay (RIBA-2) and cDNA polymerase chain reaction (cDNA PCR) for confirmation of hepatitis C virus (HCV) infection, anti-HCV reaction patterns and the presence of HCV RNA were examined in 610 blood donors and 255 non-A, non-B hepatitis patients who were positive or indeterminate in RIBA-2. Of RIBA-2-positive donors (n = 191) and patients (n = 224), 75.4 and 89.7 percent, respectively, were HCV RNA positive. The most frequently observed anti-HCV recognition patterns in HCV RNA-positive donors and patients were c22, c33c, and c100 and/or 5- 1-1 (67.3%, 57.7%) and c22, c33c (24.8%, 29.3%). Among subjects with a RIBA-2-indeterminate result, HCV RNA was detected more often in patients (n = 31) than in donors (n = 419): 67.7 and 2.1 percent, respectively. In viremic persons with single-band reactivity in RIBA-2, this reactivity was always directed against either c22 or c33c. HCV RNA was detected by cDNA PCR in none of 162 persons with only anti-c100 and/or anti-5-1-1 reactivity. Therefore, RIBA-2 reactivity against c100 in combination with 5-1-1 should not be considered positive but indeterminate. In RIBA-2-indeterminate persons, HCV RNA detection is necessary for reliable confirmation of HCV infection.     

Reliability of the third-generation recombinant immunoblot assay for hepatitis C virus

BACKGROUND: In a confirmatory laboratory, the second-generation recombinant immunoblot assay (RIBA-2) was replaced by the third- generation RIBA (RIBA-3) in March 1993. The aim of this validation study was to compare the sensitivity and specificity of RIBA-2 and RIBA- 3 in a routine setting, by using a validated hepatitis C virus (HCV) RNA polymerase chain reaction to establish plasma viremia. STUDY DESIGN AND METHODS: RIBA-2 testing was performed (March 1991-March 1993) in 593 HCV RNA-positive and 1498 HCV RNA-negative subjects. RIBA-3 testing was performed (March 1993-May 1994) in 220 HCV RNA-positive and 530 HCV RNA-negative subjects. All samples reacted for anti-HCV in enzyme- linked immunosorbent assay. RESULTS: In HCV RNA-positive individuals, the sensitivity of RIBA-3 was significantly higher than that of RIBA-2 (99.5% vs. 93.3%, p = 0.0005). This was not caused by inclusion of the NS5 antigen, but by a higher sensitivity of the antigens c33 and c100 (RIBA-2: 94.3% and 62.6%; RIBA-3: 99.5% and 88.6%). Replacement of the c22 and c100 recombinant proteins by synthetic peptides significantly reduced nonspecific reactivity against these antigens (p < 0.0001). Unfortunately, increased nonspecific reactivity against the modified c33 antigen and the new NS5 antigen canceled out this effect. Two-band reactivity occurred more often in nonviremic persons than in viremic persons (32.7% vs. 8.2%, p < 0.0001). Risk factors for HCV infection were less frequently observed in 11 blood donors with two-band reactivity than in 6 blood donors with other positive RIBA-3 patterns (18% vs. 83%, p = 0.03). CONCLUSION: The higher sensitivity of RIBA-3 significantly reduced the number of indeterminate test results in HCV RNA-positive persons. Confirmatory laboratories must be aware of the frequent occurrence of nonspecific, isolated reactivity and even nonspecific, two-band reactivity in anti-HCV enzyme-linked immunosorbent assay-reactive blood donors.