Application of a computer program to exclude additional unexpected antibodies

BACKGROUND : When a patient has produced red cell (RBC) antibodies in the past, he or she is at risk of producing additional antibodies after antigen challenge. The presence of these antibodies should be excluded before each transfusion. The following criteria are applied when using commercial test RBCs: RBCs should not express the antigen against which the previously documented antibody is directed. For other clinically significant antigens, at least one RBC sample should be from a donor who is homozygous for the encoding gene. The manual selection of such RBCs is tedious and requires experience. STUDY DESIGN AND METHODS : A computer program has been developed that generates exclusion panels (EPs) by selecting a minimum number of RBCs from commercial test panels complying with current criteria. When RBCs from a donor who is homozygous for the encoding gene are absent, the program selects, as a second-best option, RBCs from a donor who is heterozygous for that gene. The computer program developed for this study investigated the usefulness of commercially available panels from separate manufacturers in excluding the presence of additional antibodies. A list of 488 antibodies detected by a regional blood bank in 1994 was used as cases of antibodies documented in the past. RESULTS : In 61 percent of the cases, successful EPs (i.e., those complying with the criteria), consisting of three to four different phenotypes, were selected. In the remaining 39 percent of cases, it was impossible to generate successful EPs: 1 to 2 additional antibodies could not be excluded or could be excluded only by using RBCs from heterozygotes. Commercial panels differed only slightly in their efficiency in providing suitable RBCs. None of the commercial panels could provide suitable RBCs to exclude all additional antibodies in the presence of anti-c, anti-e, or anti-M. Increasing the number of RBCs from which to select EPs only slightly increased the percentage of success. CONCLUSION : Computer-aided construction of EPs quickly shows whether strict criteria can be met or whether alternative techniques should be used. It leads to a significant reduction in the number of RBC suspensions necessary to exclude additional antibodies. Results with various commercial panels differed only slightly.     

三种阳离子脂质体介导血管内皮细胞基因转染效率的比较

目的:评价不同阳离子脂质体介导基因转染血管内皮细胞的转染效率。方法:实验于2006-12/2007-02在中山大学生化实验室及广州市创伤外科研究所完成。采用增强型绿色荧光蛋白基因为报告基因,分别采用Lipofectin、Lipofectamine、Dosper3种不同的阳离子脂质体为载体,转染人脐静脉血管内皮细胞。在24孔板中,每孔加入人脐静脉血管内皮细胞悬液(1×106个细胞),各孔分别加入3种不同阳离子脂质体增强型绿色荧光蛋白质粒复合物,分别于培养24,48h后用荧光显微镜及流式细胞仪测定增强型绿色荧光蛋白在细胞内的表达及转染效率。结果:3种不同阳离子介导的增强型绿色荧光蛋白基因转染的人脐静脉血管内皮细胞内均有绿色荧光蛋白表达,24h后明显,48h后达高峰。Dosper介导组绿色荧光细胞百分比明显高于Lipofectin介导组及Lipofectamine介导组,差异有非常显著意义(P<0.01)。结论:Dosper介导的血管内皮细胞基因转染效率较高,较适合作为血管内皮细胞的基因转染载体。     

快速成型骨组织工程支架的结构及力学仿生性能特征

目的:利用显微CT的成像技术及材料力学测试,观察多孔双相磷酸钙陶瓷支架的三维结构和力学仿生性能特征。方法:实验于2004-06/2005-12在清华大学新型陶瓷与精细工艺国家重点实验室、香港中文大学威尔士亲王医院骨与关节肌肉研究室和解放军总医院骨科研究所完成。利用三维凝胶叠层成型技术和发泡法复合的方法,制备仿骨多孔双相磷酸钙陶瓷支架,经显微CT扫描得到分辨率为20μm的断层图像,并按骨形态计量方法计算三维计量参数,并与急性脑死亡年轻人股骨头(由解放军总医院骨组织库提供,已签署捐献同意书)标本负重区松质骨样本的三维参数进行统计比较。最后对双相磷酸钙陶瓷支架两个互相垂直方向和松质骨样本的长轴方向进行压缩强度试验,计算压缩强度和弹性模量,并进行统计分析。结果:①双相磷酸钙陶瓷支架的小梁平均宽度和间距低于松质骨小梁(P<0.05);支架的小梁数目和各项异性程度高于松质骨样本(P<0.05);说明支架小梁在排列上呈现更为明显的各向异性特征。②双相磷酸钙陶瓷支架的体积分数、表面积体积比及结构模型指数与松质骨样本相比差异无显著性(P>0.05),两组样本均呈明显的板层结构。③力学测试结果显示双相磷酸钙陶瓷支架材料长轴方向的强度和弹性模量高于垂直方向(P<0.05),说明支架材料具有明显的方向性。长轴方向的强度低于正常松质骨样本,但弹性模量仅比松质骨样本弹性模量高20%(P<0.05)。结论:支架材料在空隙率和表面积方面具有很好的仿生性,利于细胞的黏附和长入。同时具有明显的方向性,提高了其在排列方向上的强度。弹性模量接近股骨头松质骨,具有较好的应力顺应性。     

Selection of platelets for refractory patients by HLA matching and prospective crossmatching

A multi-site clinical study compared platelets chosen for refractory patients by prospective platelet crossmatching using stored donor platelets and HLA-based selection. Seventy-three patients who were refractory to random-donor platelets received two plateletpheresis components, one chosen by HLA-based criteria and the other by crossmatching. Patients were carefully evaluated to exclude nonimmune factors that could adversely affect transfusion results. Each of the five study sites used a crossmatch procedure with which it had experience. Results from this study indicate the following: 1) The overall rate of successful transfusion was similar when an HLA-based method of donor selection that includes all grades of matching and mismatching was compared to a crossmatch-based method of donor selection. 2) HLA-based selection that restricts recipients to grade A and BU matches was superior to a selection method based upon crossmatching alone. Donor selection based on HLA matching (grades A or BU) was also superior to selection based on any degree of HLA mismatching (grades BX, C, or D). 3) Selection of donors based on HLA-cross-reactive groups (defined by in vitro serologic crossreactivity) was no more successful than that based on grade C and D mismatches and was no more successful than selection by crossmatching alone. 4) Lymphocytotoxic and platelet antibodies were not detected in many of the enrolled patients, even though patients demonstrating nonimmune factors were eliminated from the study. It can be concluded that HLA-compatible (grades A and BU) platelets provide optimal support for refractory patients, but that crossmatch-selected platelets are acceptable as an alternative component.     

人类牙乳头间充质细胞向成牙本质细胞定向的诱导分化

目的:探讨人牙乳头间充质细胞向成牙本质细胞的分化机制和分化过程。方法:实验于2004-04/2005-03在四川大学华西口腔医学院口腔生物医学工程教育部重点实验室完成。①实验材料:选择四川大学华西第二医院自然流产的三四个月胎龄的人胚胎(孕妇知情同意,经过医院伦理委员会批准),胰岛素样生长因子Ⅰ和碱性成纤维细胞生长因子(均购自美国Sigma公司)。②实验分组:实验分为空白对照组、胰岛素样生长因子Ⅰ组、碱性成纤维细胞生长因子组和联合组。③实验干预:在建立人牙乳头间充质细胞体外培养模型的基础上,用不含白血病抑制因子的DMEM/F12培养基作为基础培养液,分别用浓度为10μg/L的胰岛素样生长因子Ⅰ、浓度为100μg/L的碱性成纤维细胞生长因子以及同时用这两种因子诱导人牙乳头间充质细胞向成牙本质细胞定向分化。④实验评估:采用倒置显微镜、免疫细胞化学和反转录-聚合酶链反应等方法从形态学和功能方面检测细胞的变化。结果:①培养和诱导细胞形态学变化及碱性磷酸酶活性:诱导细胞培养7d时,联合组和胰岛素样生长因子Ⅰ组的培养细胞均呈现单一胞浆突起,形态上出现成牙本质样细胞改变,细胞的碱性磷酸酶活性明显增高,联合组细胞的胞浆突起更明显,细胞的碱性磷酸酶活性更高;碱性成纤维细胞生长因子组与对照组比较,细胞变化不明显。②细胞免疫化学结果:联合组和胰岛素样生长因子Ⅰ组牙本质涎磷蛋白的免疫细胞化学染色胞浆呈阳性。③细胞hDSPPmRNA的表达:联合组和胰岛素样生长因子Ⅰ组细胞经反转录-聚合酶链反应后获得约599bp的特异性片段,表明两组细胞在mRNA水平表达特异性牙本质涎磷蛋白。而其余两组未见表达。结论:胰岛素样生长因子Ⅰ能刺激人牙乳头间充质细胞向功能性成牙本质细胞样细胞分化,碱性成纤维细胞生长因子可产生协同作用。     

Monitoring transfusionist practices: a strategy for improving transfusion safety

BACKGROUND: Data from New York State indicate that about 1 of every 33,000 red cell units transfused is ABO-incompatible with the recipient. National application of these data suggests that as many as 360 ABO-incompatible whole blood and red cell transfusions might occur annually in the United States. Phlebotomy and blood bank laboratory errors cause some of these ABO-incompatible transfusions, but the greatest number result either partially or solely from the failure of transfusionists to identify properly either a patient or the blood component a patient receives. STUDY DESIGN AND METHODS: A quality assessment/quality improvement (QA/QI), process is described that allowed for the direct oversight (monitoring) of transfusionists' practices and for the assessment of institutional policies for blood administration. RESULTS: At the beginning of the QA/QI process, monitoring of blood administration practices revealed that a variance from institutional blood administration policy occurred during 50 percent of blood and component transfusions. As a result of the QA/QI process, the percentage of transfusions with an associated variance from institutional policy dropped to nearly zero. CONCLUSION: The QA/QI process described in this report, or one similar to it, could improve transfusion safety and serve as a model for increased involvement by transfusion service medical directors in the oversight of transfusionists' practices.     

Blood transfusion costs: a multicenter study

The cost of delivering a unit of blood (whole blood or red cells) to a hospitalized patient was examined in 19 United States teaching hospitals. The average hospital acquisition cost was calculated by using the prices charged by regional blood centers for blood products. To this cost was added an estimate of costs incurred by hospitals for handling, testing, and administering blood. Across study sites, the average hospital cost per unit transfused was $155 and the average charge to the patient was $219. Acquisition cost, the price that hospitals pay for blood, was 37 percent of the total cost to the hospital; the other 63 percent of the hospital cost included costs for blood bank handling (13%), laboratory tests (43%), and blood administration (7%). Significant variations in blood transfusion cost were found within our sample. Most of the variability can be attributed to geographic location of the blood supply source, type of red cell product transfused, prices charged by blood transfusion services, and the frequency of laboratory tests. The results of this transfusion cost study may be helpful in determining the costs of health care delivery, especially when blood transfusions are indicated.     

INDIGENOUS, NORMAL, AND AUTOCHTHONOUS FLORA OF THE GASTROINTESTINAL TRACT

The bacterial flora of the gastrointestinal tract differs qualitatively and quantitatively from one colony of mice to another. Certain components of this flora, however, are always present in large and approximately constant numbers in healthy adult mice, irrespective of the colony from which the animals are derived. Lactobacilli and anaerobic streptococci are extremely numerous in the stomach, the small intestine, and the large intestine. In contrast, organisms of the bacteroides group proliferate only in the large intestine. These three bacterial species persist at approximately constant levels in their characteristic localization throughout the life span of healthy animals. They are closely associated with the walls of the digestive organs, and are probably concentrated in the mucous layer. A few experiments carried out with rats and young swine indicate that lactobacilli are also present in large numbers in the stomach of these animal species. It is suggested that some of the components of the gastrointestinal flora have become symbiotic with their hosts in the course of evolutionary development and thus constitute a true autochthonous flora. The other components of the indigenous flora are acquired early in life either through accidental contact or because they are ubiquitous in the environment. The "normal" flora is that which is always present in the environment of the animal colony under consideration.