Changes in cytosolic calcium concentrations and cell morphology in single platelets adhered to fibrinogen-coated surface under flow

Changes in intracellular calcium concentration [Ca2+]i of fura-2-loaded human platelet during its adhesion to a fibrinogen-coated surface were studied, using a flow chamber mounted on an epifluorescence microscope equipped with digital-ratio imaging. Adherent platelets were individually mapped under a scanning electron microscope to establish the possible correlation between adhesion-associated shape alterations and [Ca2+]i changes. We found that 1) there was no immediate [Ca2+]i elevation on platelet adhesion; 2) [Ca2+]i changes varied drastically platelets with a lag time ranging 10 to 200 s, averaging about 1 minute; 3) the pattern of [Ca2+]i changes varied drastically among individual adherent platelets; 4) the degree of [Ca2+]i elevation appeared to correlate with the extent of morphology change, with the vast majority ( > 90%) of spread platelets showed detectable [Ca2+]i changes; 5) neither morphological nor [Ca2+]i changes correlated with the lag time; 6) platelets treated with dimethyl-BAPTA (15 mumol/L) underwent normal shape change without [Ca2+]i elevation; 7) cytochalasin D (10 mumol/L) inhibited both shape change and [Ca2+]i elevation; 8) colchicine (1 mmol/L) was ineffective in both regards. We conclude that although platelet adhesion-associated shape changes may be accompanied with heterogeneous [Ca2+]i changes that are microfilament-dependent, [Ca2+]i changes do not happen immediately after platelet-surface contact and they are not required for adherent platelets to undergo postcontact morphological changes.     

Frequency of platelet-specific antigens among Koreans determined by a simplified immunofluorescence test

The frequencies of platelet-specific antigens among Oriental populations have not been well studied. This article reports the determination of the frequency of five major platelet-specific antigens among Korean blood donors. Both the PlA1 (Zwa) and Yukb antigens were positive in all of the 126 Koreans tested. Baka and Yuka antigens were positive in 110 (87.3%) and 2 (1.6%) of the 126 subjects, respectively. Ten (11.5%) of 87 Koreans had PlA2 (Zwb) antigens. A simplified immunofluorescence test, the adhesion slide immunofluorescence test, was devised for platelet antigen typing.     

Unexplained hepatitis C virus antibody seroconversion in established blood donors

BACKGROUND: Understanding of the epidemiology and natural history of hepatitis C virus (HCV) infection is incomplete without reference to the early phase of infection. The prevalence of HCV infection is well documented in numerous reports. The seroconversion pattern in previously antibody-negative blood donors provides a model for the study of the incidence and transmission of HCV infection. STUDY DESIGN AND METHODS: Records of HCV antibody tests at the West Midlands Blood Transfusion Centre were reviewed to determine the seroconversion rate in 1994 among previously anti-HCV-negative blood donors. Seroconverting donors were counseled to investigate the possible routes of infection. RESULTS: In 1994, blood donations (n = 256,935) were collected from 149,370 donors; 24 donors (0.016%; 1/6224) were positive in the screening enzyme-linked immunosorbent assay (ELISA) and the third- generation recombinant immunoblot assay (RIBA-3). Two donors previously negative for HCV antibody in ELISA were positive in both tests in 1994. Four donors positive in ELISA and indeterminate in RIBA-3 in 1993 reacted positively in both tests in 1994. One donor negative for HCV antibody on previous screening reacted positively in ELISA and was indeterminate in RIBA-3 in 1994 and has become positive in both tests in 1995. A further 43 donors negative for HCV antibody on previous screening reacted positively in ELISA and were indeterminate in RIBA-3 in 1994. CONCLUSION: Documented seroconversion can take place in the absence of exposure to recognizable risk factors for the infection. The index donation or the donation immediately preceding seroconversion may be positive for HCV RNA in the polymerase chain reaction.     

模拟航天超重状态下冲击过载致腹部脏器损伤的实验研究

目的 制作模拟航天超重状态下冲击过载致腹部脏器损伤的实验动物模型,探讨其损伤特点.方法 实验动物为ICR小鼠,利用离心机和脾中部横夹法造成模拟航天超重状态下冲击过载致腹部脏器损伤的实验动物模型,分时相测定血常规和组织病理学观察.结果 模型制作后,各时相/组实验动物的血常规中WBC、RBC、HGB、MCH、MCHC、PLT较正常组均有变化(P＜0.05);各时相/组实验动物的病理变化具有一定规律,其中病理变化以脾脏最为明显.结论 初步探讨了模拟航天超重状态下冲击过载致腹部脏器损伤后的损伤特点,总结致伤规律,可为进一步开展相关航天医学研究提供参考.     

Evaluation of the inferior vena cava by sonography and venography in children with renal and hepatic tumors

Ultrasonography was used to examine 81 children with intra-abdominal or retroperitoneal malignancies for tumor extension into the inferior vena cava (IVC). In seven of the 18 patients with Wilms tumors and three of the seven patients with hepatic tumors, the IVC ws sonographically abnormal. Venography was also performed in five patients with Wilms tumors. However, percutaneous transfemoral venacavography did not always allow differentiation between extrinsic compression and intracaval tumor. It is suggested that venacavography, when necessary, should be performed via the brachial vein route and that the catheter be advanced into the right atrium. If an injection in this chamber does not result in enough reflux into the retrohepatic IVC for adequate evaluation, the catheter should be advanced into the IVC and a second injection made. However, ultrasonography is the preferred modality for evaluation of the IVC in children because it is the most accurate method and is noninvasive. Real-time ultrasonography makes it possible to distinguish between tumor extension into the lumen of the IVC and extrinsic compression of the vessel.