Comparative study of three methods to detect free plasma antiplatelet antibodies

We have compared three techniques for the detection of plasma circulating antiplatelet antibodies, i.e., the platelet suspension immunofluorescence test (PSIFT), the platelet radioactive antiglobulin test (PRAT), and the monoclonal antibody immobilization of platelet antigens (MAIPA). Frozen plasma samples from patients with idiopathic thrombocytopenic purpura or HIV-associated thrombocytopenia were used in the study. The PSIFT and PRAT showed the appropriate ease of performance necessary for screening purposes. The PSIFT is free of radioactivity hazards, but seemed to be less sensitive than the PRAT. The MAIPA is a useful tool to detect antibodies against glycoproteins (GPs) Ib/IX and IIb/IIIa. However, in comparison to PSIFT and PRAT, MAIPA is more time consuming, requires considerable technical expertise, and the identification of antiplatelet activity is highly dependent on the selection of an appropriate primary anti-GP monoclonal antibody. This could explain the lower prevalence of antiplatelet activity detected by MAIPA, in comparison to the frequency provided by the PSIFT and PRAT.     

Novel methods to monitor antigen-specific cytotoxic T-cell responses in cancer immunotherapy

Monitoring cytotoxic T lymphocyte (CTL) responses to tumor antigens that have been defined at the molecular level has become essential to assess novel approaches to the specific immunotherapy of cancer. Nevertheless, because of the low affinity of the interactions between T-cell receptors and their ligands, there are no straightforward, well-standardized methods to meet this need. In this review, we describe several novel methods to track antigen-specific CTL responses.     

Development of a model system to compare cell separation methods for the isolation of fetal cells from maternal blood

Genes for Prader Willi syndrome/Angelman syndrome are homologous to genes for fragile X syndrome. Genetic imprinting and expanded trinucleotide repeats cause mental retardation, autism and aggression.     

Somatosensory evoked potential monitoring used to compare the effect of three asymmetric sternal retractors on brachial plexus function

OBJECTIVES: Patients with spinal cord injury (SCI) and chronic indwelling catheters are known to be at increased risk of bladder malignancy. "Decatheterization" by clean intermittent catheterization, external condom catheterization, or spontaneous voiding is thought to reduce the risk by decreasing the chronic mucosal irritation and rate of infection. We examined two Department of Veterans Affairs (DVA) data bases to test this theory. METHODS: A population-based retrospective analysis of invasive treatments for carcinoma of the bladder in all DVA hospitals was conducted using computerized inpatient files from fiscal years 1988 to 1992. RESULTS: One hundred thirty patients with bladder malignancy were identified from a pool of 33,565 patients with SCI (0.39%). All 130 patients underwent either radical cystectomy (n = 63, 48%) or transurethral resection of bladder tumor (n = 67, 52%). The 30-day perioperative mortality and overall 5-year survival rates were 2 (1.5%) and 49 (38%) of 130, respectively. Of the 130 patients analyzed, 42 (32%) had adequate data available regarding tumor pathologic findings and method of bladder management for analysis. The average age at diagnosis was 57.3 years. The histologic finding was transitional cell carcinoma in 23 (55%), squamous cell carcinoma in 14 (33%), and adenocarcinoma in 4 (10%) of 42. Bladder management was an indwelling urethral catheter in 18 (43%), suprapubic catheter in 8 (19%), clean intermittent catheterization in 8 (19%), and condom catheter in 6 (14%) of 42 patients. Squamous cell carcinoma was more common in patients with indwelling urethral catheters and suprapubic tubes (11 of 26, 42%) than in those using clean intermittent catheterization, condom catheterization, or spontaneous voiding (3 of 16, 19%). CONCLUSIONS: Bladder cancer was diagnosed in approximately 0.39% of this large SCI population during a 5-year period. Most cancers (55%) were transitional cell carcinomas. Squamous cell carcinoma was more common in patients with SCI and indwelling catheters than those without chronic catheterization. These data continue to suggest that avoidance of indwelling catheters, when feasible, is the preferred method of bladder management in patients with SCI.     

电化学方法在不锈钢腐蚀研究中的应用现状及发展趋势

电化学手段可以实现对不锈钢材料的快速评价和腐蚀机理研究,因而受到广泛应用。在不锈钢耐蚀性评价方面,最常采用的电化学手段主要有腐蚀电位测试、交流阻抗测试、恒电位极化测试以及循环动电位极化测试。本文分别针对上述四种电化学方法在不锈钢耐蚀性评价上的应用情况进行了介绍,明确了各种检测方法的特点。腐蚀电位及交流阻抗测试是无损检测手段,可以满足长周期腐蚀监测需求;恒电位极化和循环动电位极化测试可以获得材料的极化特征参数,有利于对材料的腐蚀机理及耐蚀性进行评价。结合当前的不锈钢腐蚀研究现状,展望了电化学方法在腐蚀研究领域的发展趋势:未来电化学方法将更多作为腐蚀调控手段,需要结合其他检测技术实现对不锈钢腐蚀过程的精细分析。      

Analytic assessment of the various bioimpedance methods used to estimate body water

Knowledge of patient fluid distribution would be useful clinically. Both single-frequency (SF) and impedance modeling approaches are proposed. The high intercorrelation between body water compartments makes determining the best approach difficult. This study was conducted to evaluate the merits of an SF approach. Mathematical simulation was performed to determine the effect of tissue change on resistance and reactance. Dilution results were reanalyzed, and resistance and parallel reactance were used to predict the intracellular water for two groups. Results indicated that the amount of intracellular and extracellular water conduction at any SF can vary with tissue change, and reactance at any SF is affected by all tissue parameters. Modeling provided a good prediction of dilution intracellular and extracellular water, but an SF method did not. Intracellular, extracellular, and total body water were equally predicted at all frequencies by SF resistance and parallel reactance. Extracellular and intracellular water are best measured through modeling, because only at the zero and infinite frequencies are the results sensitive only to extracellular and intracellular water. At all other frequencies there are other effects.     

实验室测量审核结果的评定方法研讨

对多种类型测量审核活动的结果评价方法进行较为系统的研讨。关于测量审核重复性评定:采用单一试样时,可依据方法重复性限r评定;采用能力验证分割试样时,可依据稳健统计实验室内Z比分(ZW)评价。关于测量审核再现性评定:采用能力验证试样时,可依据稳健统计实验室间Z比分(Z或ZB)评价;采用具有指定值的试样时,可依据95%置信水平临界差评定,不同标准方法对于精密度的表述方式不同,其临界差的计算方法也不同,本文介绍了根据不同标准提供的参数计算临界差的方法;当实验室提供不确定度时,其结果也可依据指定值的不确定度En值评定。     

Immunoglobulin V region sequences of two human antiplatelet monoclonal autoantibodies derived from B cells of normal origin

Autoimmune thrombocytopenia has been attributed to the presence of antiplatelet autoantibodies which mediate platelet destruction. The derivation of these autoantibodies is presently unknown. While normal B cells do not produce these autoantibodies in vivo, it has been demonstrated in vitro by somatic cell hybridization that the B lymphocytes of nonthrombocytopenic individuals have the potential to produce antiplatelet autoantibodies. Antigen specificities of these antibodies are similar to those seen in autoimmune thrombocytopenic purpura and the lupus anticoagulant syndrome. The immunoglobulin V region genes encoding two such human monoclonal antiplatelet antibodies, an anti-GP IIb (STO 171) and an anti-phospholipid antibody (STO 103) derived from tonsillar lymphocytes of a non-thrombocytopenic male, have now been sequenced. These antiplatelet antibodies were found to be encoded by unmutated germline VH and VK genes. The third complementarity determining region (CDR3) of the genes encoding both of these antibodies have unique D regions with evidence of N-nucleotide additions, and the light chain genes show VK-JK junctional diversity. STO 103 is encoded by the VH4 V71-2 germline gene and a truncated JH4 gene. The light chain gene showed closest homology with the VK4 Humk18 gene and JK2 gene. STO 171 showed closest homology with the VH4.18 germline gene and had a complete germline JH6 gene. The light chain of STO 171 is encoded by the VK3 Humkv325 germline gene, which is also used by some rheumatoid factors and cold agglutinins, and a JK4 gene. Although these antibodies were not derived from circulating B cells or found to be actively producing antibody at the time they were harvested, it is possible that naturally occurring antibody producing B cells, similar to those represented here, are recruited for the development of pathogenic autoantibodies in immune thrombocytopenia.     

Statistical considerations for design and analysis of a multiperiod crossover study to compare two treatments for migraine headache

The purpose of this paper is to discuss a long-term, multiperiod crossover study to compare two treatments for migraine headache. Principal attention is given to the analysis of an example in which patients randomly received a treatment sequence with test drug for three migraine headaches and placebo for one. An issue that requires attention for this example is the influence of a carryover effect for test drug that was greater when placebo was the subsequent treatment than when test drug was the subsequent treatment. A way to address this issue without excessive loss of power is to consider tests of "total treatment effects," which are weighted averages across headaches of differences between average response to test drug and average response to placebo. Since these weighted averages are linear combinations of treatment effects and carryover effects, their use requires an argument that carryover effects are at least partly a further form of treatment effects. For the example in this paper, this argument is realistic because the test drug could have provided much better relief to migraine headache than other treatment patients might have previously used. A second purpose of the paper is to present some alternative designs for situations like that represented by the example. The structure of variances for alternative specifications for treatment comparison is provided for models of interest for these designs.     

Modern methods for measurement of basilar membrane displacements

Basilar membrane displacements in response to sound at threshold intensities are in the fractional Angstrom range. Visual measurements, as used by Bekesy in his pioneering studies, are by definition limited to values above 10 000 A. The present paper discusses a number of modern techniques capable of taking measurements at lower Anstrom levels: One-point methods (capacitive probe, Mossbauer effect, laser interferometry, and optical heterodyne spectroscopy) and pattern-assessing methods (time-averaged and real-time holography). Advantages and disadvantages of these methods are being discussed.     

Paternity study applying DNA polymorphism: evaluation of methods traditionally used in Chile

Simultaneous detection of several VNTR loci using a single DNA probe is the basis of the technique called "DNA fingerprint" (DNAfp) of increasing application in parenthood identification. According to the data gathered by different laboratories worldwide, father exclusion can be made in a larger number of cases when compared with the customary tests based on erythrocyte antigens. The question could then be whether DNAfp will completely replace erythrocyte antigens tests. We report here our experience in applying DNAfp to 92 samples corresponding to 34 paternity cases and comparing these with the results obtained with the antigens of the systems ABO, Rh, MNSs, Duffy and Kidd. Most of the HaeIII/digested DNA samples produced 13 to 16 bands larger than 4.3 Kb (average 14,0761 +/- 2,205). Average band sharing between pairs of unrelated individual was 1,9107 +/- 1,083. Two cases presenting an a posteriori probability of being the father of 80.7% and 76.5% by erythrocyte antigens were clearly excluded by DNAfp. All exclusions made by antigens were confirmed by DNAfp. In the cases reported as father "rather probable" (28 cases) by DNAfp, these shared with the child 6,7407 +/- 1.7 bands on average. Because of time, cost and simplicity we favor a procedure starting with the antigens test and continuing with DNAfp only when an exclusion is not possible. Economy will increase as the number of exclusions increases.     

Scanning electron microscopy in the study of surface treatment methods used in the repair of porcelain-fused-to-metal restorations

According to the literature the ceramic crowns are damaged in 1%-9% of the cases. In order to repair the damage with polimers, first the exposed surfaces have to be made microretentive. Our aim was to investigate with scanning electronmicroscope how the different surface treatment methods modify the structure of metal and ceramic surfaces. We applied two different methods of grinding: 40 microns grained diamond, K1 burs stone (SILISTOR) for ceramic and metal surfaces. The third surface treatment was the application of HF acid for ceramic surface and the sandblasting for metal surface. To achieve microretention the latter mentioned methods increased the most the retentive surface.     

A simple costing of three methods used to prepare endoscopy equipment

The paper describes a DRIM-1 X-ray monitor which directly measures and records the product of an absorbed (exposure) dose and the actual area of X-ray beam onto the outside surface of the depth diaphragm (cGy.cm2). The principle of action of the device is based on the measurement of the charge coming from the detecting unit--a preamplifier ionization chamber. The device may be used to control the time-stability of a radiation signal in the X-ray apparatus.     

Studies of the methods used for the determination of the digestibility of crude fats in calves

An investigation was made of methods used for the exact determination of the crude content and crude extract of faeces. The following methods were examined: (1) Following treatment with hydrochloric acid a 1:1 mixture of ether and petroleum ether was used. (2) Following hydrolysis with hydrochloric acid extraction with ether was carried out immediately from the aqueous phases. (3) The analysis was carried out with Folch's solvent. A 1:1 mixture of methanol and chloroform was used. (4) The faeces were dried with infrared lamps and crude fat extraction was carried out with Folch's solvent. A 1:1 mixture of methanol and chloroform was used. (5) The faeces were dried with infrared lamps and extraction with ether was done in a Soxhlet apparatus. Nearly identical results were obtained with methods 1 and 2 or 3 and 4 in determining the content of crude extract, the acid number and the percentage proportion of fatty acids. Essential differences were found between methods 1 and 2 and methods 3 and 4. The most reliable results were obtained by using method (2). Method (5) was found to be most suitable for large-scale testing. Values for the content of crude extract in the faeces were somewhat lower (0.78%-1.2%) when determined by method (5). These variations were not significant statistically. (P greater than 5%). No significant differences were observed between methods (2) and (5). It was thus established that method (5) is best suited for estimating the crude extract of the faces. The faeces of calves were found to contain a high proportion of unsaponifiable matter. This proportion was subtracted from the percentage of crude extract and the amount of faecal crude fat was thus estimated. Very small but statistically significant differences were found by converting digestibility data of crude extract into those of crude fat. Hence, for future work the most appropriate method appears to be the estimation of the crude extract in feedingstuffs.     

Recombinant IA-2 expressed in E. coli can be used for the routine detection of autoantibodies in Type-I diabetes

We have investigated the possibility of measuring autoantibodies to IA-2 (IA-2A) using recombinant protein expressed in E. coli in a new radioassay. The intracellular part of IA-2 (IA-2ic) was expressed in E. coli as a biotinylated fusion protein and affinity-purified on a streptavidin column. The average yield of IA-2ic was about 1 mg purified protein from one litre of culture medium with E. coli. We could demonstrate the immunological activity of this material by blocking the autoantibody reactivity to in vitro synthesised IA-2ic. The IA-2ic fusion protein was then radiolabelled with 125I, purified by HPLC, and used in an immunoprecipitation assay for the detection of IA-2A. Sera from 46 of 68 (67%) patients with Type-I diabetes were positive by this radioassay, in contrst to only 2 of 50 (4%) patients with autoimmune thyroid disease and 1 of 114 (1 %) controls. There was a correlation between this radioassay and the previously established radioligand assay using synthesized 35S-methionine-labelled IA-2ic in vitro (r = 0.79, p < 0.001). We conclude that E. coli-derived IA-2 has the correct immunogenic conformation, and can be used for the detection of IA-2A with a similar sensitivity and specificity as the validated radioligand assay. This new assay can facilitate the measurement of IA-2A in routine laboratories where the radioligand assay is inconvenient or not available.