Absolute quantitation of gallium-67 citrate accumulation in the lungs and its importance for the evaluation of disease activity in pulmonary sarcoidosis

Our modification of a method for the absolute quantification of gallium-67 uptake in lungs with a scintillation camera and computer is described. The uptake of ⁶⁷Ga in lungs, expressed in percentage of administered radioactivity, was determined by the transmission-emission method. We proved theoretically and experimentally that a ⁶⁷Ga planar source could be replaced with a ⁵⁷Co planar source. The performance of lung perfusion scans allows a more accurate delineation of the regions of interest on gallium scans. The method was applied to control subjects (n=27) and to patients (n=114) suffering from biopsy-proven pulmonary sarcoidosis (28 with inactive and 86 with active disease). The obtained results were compared with chest X-ray findings, the percentage of lymphocytes in the bronchoalveolar fluid (BAF-ly%), and serum angiotensin-converting enzyme (SACE) values. The method seems suitable for the assessment of disease activity in sarcoidosis. It is more accurate in detecting parenchymal involvement in lung sarcoidosis than the commonly used X-ray criteria. No correlation was found between ⁶⁷Ga uptake and the BAF-ly% and SACE values. Correspondence to: M. Mysliveek     

Matrix effects: the Achilles heel of quantitative high-performance liquid chromatography-electrospray-tandem mass spectrometry

High-performance liquid chromatography coupled by an electrospray ion source to a tandem mass spectrometer (HPLC-ESI-MS/MS) is the current analytical method of choice for quantitation of analytes in biological matrices. With HPLC-ESI-MS/MS having the characteristics of high selectivity, sensitivity, and throughput, this technology is being increasingly used in the clinical laboratory. An important issue to be addressed in method development, validation, and routine use of HPLC-ESI-MS/MS is matrix effects. Matrix effects are the alteration of ionization efficiency by the presence of coeluting substances. These effects are unseen in the chromatogram but have deleterious impact on methods accuracy and sensitivity. The two common ways to assess matrix effects are either by the postextraction addition method or the postcolumn infusion method. To remove or minimize matrix effects, modification to the sample extraction methodology and improved chromatographic separation must be performed. These two parameters are linked together and form the basis of developing a successful and robust quantitative HPLC-ESI-MS/MS method. Due to the heterogenous nature of the population being studied, the variability of a method must be assessed in samples taken from a variety of subjects. In this paper, the major aspects of matrix effects are discussed with an approach to address matrix effects during method validation proposed.     

重组PCR构建bcr—abl mRNA竞争RT—PCR内标物

目的竞争ＰＣＲ可用于ｍＲＮＡ的定量测定，为了得到白血病中ｂｃｒ－ａｂｌｍＲＮＡ定量ＰＣＲ的竞争内标物。方法利用重组ＰＣＲ技术，实施对ｂ３ａ２型ｂｃｒ－ａｂｌｃＤＮＡ中一２７６ｂｐ片段的缺失法定点突变。结果经ＤＮＡ序列分析证实，重组后的ｃＤＮＡ片段与重组前相比，５′和３′端大部分序列相同，仅中间５５ｂｐ的部分序列缺失，同时引入１９ｂｐ外源ＤＮＡ片段，即净缺失３６ｂｐ，得到２４０ｂｐ的重组ＰＣＲ产物。较ｂ２ａ２型ｂｃｒ－ａｂｌｃＤＮＡ相应的２０１ｂｐ扩增片段长３９ｂｐ，使之适于作为ｂ３ａ２和ｂ２ａ２型两类ｂｃｒ－ａｂｌｍＲＮＡ定量ＰＣＲ的通用内标物。结论表明重组ＰＣＲ是一种获得靶基因的竞争性内标物的简便而可靠的方法     

以cRNA为内在参照物测定人支气管肺泡洗出液细胞TNFα mRNA的含量

本文尝试了以 cRNA 为内在参照物,以逆转录—DNA 聚合酶链反应测定人支气管肺泡洗出液细胞肿瘤坏死因子αmRNA 含量的方法。自一重组质粒(pAW 108)体外转录出互补 RNA(cRNA),此cRNA 含两段肿瘤坏死因子α特异性引物序列。将 cRNA 用分光光度计定量后取一定量和提取自人支气管肺泡洗出液细胞的 mRNA 混在一起做逆转录,得到的 cDNA 混合物经1:3稀释后以肿瘤坏死因子α特异性引物做 DNA 聚合酶链反应放大.在反应中加入一定量末端标记~(32)P 的引物.放大产物经琼脂糖凝胶电泳分带,将各区带切下做β-液闪计数.以各区带的放射性计数对 cRNA 含量和细胞数做图,根据已知的 cRNA 的含量从图上可以推出一定量的细胞中的肿瘤坏死因子αmRNA 的含量。     

Quantitative Evaluation of Guinea Pig Spermatogenesis: Epon Versus Paraffin Embedding

A quantitative evaluation of spermatogenesis in the guinea pig was made at the light microscope level following improved methods of fixation and plastic embedding. The pattern of germ cell differentiation was studied by counting the average number of germ cell nuclei per Sertoli cell nucleus during the seminiferous epithelial cycle. Appreciable cell loss occurred during spermatogenesis. As a result, only 20.8% of the theoretically possible number of spermatozoa were produced from each spermatogonium. A slightly better yield of germ cells was obtained from Epon sections in comparison to paraffin sections. Epon sections can be effectively used for quantitative analyses of various cell populations in small biopsy specimens of testis tissue.     

Comparison of 2 highly automated nucleic acid extraction systems for quantitation of human cytomegalovirus in whole blood

The aim of the study was to evaluate analytical performances of the COBAS Ampliprep and to compare extraction from whole blood on the COBAS Ampliprep and on the MagNA Pure instruments (Roche Diagnostics, Mannheim, Germany) for quantifying human cytomegalovirus (HCMV) DNA with real-time polymerase chain reaction (PCR). The limit of detection using the COBAS Ampliprep was 10 copies/run (150 copies/mL, i.e., 2.20 log(10) copies/mL). Quantitation of HCMV-DNA was linear from 3.0 to 6.0 log(10) copies/mL. The intra-assay variations ranged from 11.1 % to 0.4 % and interassay variation was 11.3 %. A total of 107 samples were tested using both extraction systems. Only 3 samples gave discrepant results. Correlation between HCMV virus loads was good (r = 0.73) (P < 0.001). Mean virus load was lower (-0.49 log(10) copies/mL) with COBAS Ampliprep than with MagNA Pure extraction system. Both MagNA Pure and COBAS Ampliprep provide reliable and high-throughput platforms for real-time PCR HCMV quantitation of DNA extracted from whole blood.     

Improving the quantitation accuracy in noninvasive small animal single photon emission computed tomography imaging

Introduction

Noninvasive imaging of small animals to measure biodistributions and pharmacokinetics of radiolabeled agents is increasingly seen as an effective alternative to external counting of tissues obtained by sacrifice and dissection. However, we have observed important disagreements in measuring the accumulation of ¹¹¹In-labeled antibodies in organs such as liver and kidneys when comparing imaging to ex vivo counting in the same animals. This study was conducted to establish whether this discrepancy could be minimized by selecting the region of interest (ROI) in images at the appropriate color threshold and by correcting for the estimated radioactivity within the blood pool of these organs during imaging.

Methods

Vials with known concentrations of ¹¹¹In as phantoms were imaged on a Bioscan NanoSPECT/CT. Thereafter, an ¹¹¹In-DTPA-IgG antibody as the test agent was administered intravenously to normal rats, and whole body acquisitions were obtained at 2, 24 or 48 h. Immediately following imaging, the animals were sacrificed, the tissues were removed for ex vivo counting and the radioactivity accumulations were then compared.

Results

The phantom measurements showed that accuracy depended upon setting the correct ROI and that, in turn, depended upon setting the appropriate threshold of the color scale. Under the most unfavorable conditions, this error did not exceed 60%. Compared to the results of ex vivo counting, quantitation by imaging provided high values in liver and kidneys at all three time points by as much as 140%. However, by using the blood radioactivity at the time of sacrifice and the known blood volume in these organs, the disagreement was reduced in all cases to below 25%.

Conclusion

In this study, the discrepancy in quantitating organ radioactivity accumulations between noninvasive imaging and necropsy was primarily due to blood pool radioactivity contributing to the in vivo images. The discrepancy may be minimized by subtracting an estimate of this contribution.     

Reference genes evaluated for use in infectious pancreatic necrosis virus real-time RT-qPCR assay applied during different stages of an infection

The stability of 6 reference genes, 18S, β-actin, RPS20, eEF1α, G6PDH and GAPDH, was examined in tissues from Atlantic salmon (Salmo salar) and Chinook salmon embryo cells (CHSE-214). The main objective of this study was to determine the most suitable reference genes for use for the normalisation of data in quantitative real-time RT-qPCR assays conducted on infected tissues. The tissue samples selected for analysis were taken from head kidney and pylorus and collected at different time points during a challenge experiment with infectious pancreatic necrosis virus (IPNV). The stability of some of the reference genes was also studied in infected CHSE-214 cells. The ranking of the genes examined was carried out using the geNorm program. This program determines the most stable genes from a set of genes tested in a given cDNA sample. The stability of the reference genes varied in different tissues and in the cell line at different stages of infection with IPNV. This study demonstrated that tissue-specific combinations of reference genes must be used to normalise real time data for use for the quantitation of IPNV.     

几种戊型肝炎试剂的比较及IgG抗体定量方法的建立

目的 利用多种抗戊型肝炎病毒(HEV)IgM、IgG检测试剂对戊型肝炎恢复期血清进行确认,建立戊型肝炎病毒ISG抗体的定量检测方法,初步应用于戊型肝炎疫苗接种后抗体效价检测.方法 应用多种抗-HEV IgM、IgG试剂对江苏省确诊的戊型肝炎病人发病后6个月以上的血清样品进行检测;抗-HEV IgG阳性样本应用ORF2 C端抗原和ORF3抗原Western blot进行确认,用WHO抗-HEV Ig标准品标定确认阳性的混合血清抗-HEV IgG的含量,制备抗-HEV IgG定量检测的线性标准品,建立戊型肝炎疫茼免疫后抗体定量检测方法.结果 42份戊型肝炎恢复期血清采用G、K、MP、万泰4种抗-HEV IgG试剂检测的阳性率分别为71.4%、78.6%、92.9%、100%,G试剂阳性率低于MP(X2=5.19,P<0.05)和万泰试剂(χ~2=11.76,P<0.01),K试剂阳性率明显低于万泰试剂(χ~2=7.96,P<0.01);MP、G、X、万泰、K试剂抗-HEV IgM试剂的阳性率分别为21.4%、7.1%、21.4%、64.3%、78.6%;万泰和K试剂的阳性率均明显高于MP(χ~2=15.75,P<0.01;X2=27.43,P<0.01).Western blot确认试验分别有30和18份血清与ORF2、ORF3抗原有阳性反应.13份血清混合为HEV-D01,其抗-HEV IgG浓度经标定为57.94 U/ml.制备了浓度范围为0.077～0.877 U/ml的7个1.5倍系列稀释的定最线性标准品,用于戊肝疫苗临床试验,试验过程中对高、中、低浓度质控品的定量值均在均数±2s范围内,变异系数(cv)分别为16%、16%、12%.结论 不同抗-HEV IgM和IgG试剂之间的质量存在较大差别,建立了抗-HEV IsG定量检测标准品,适用于戊肝疫苗的临床血清抗体IgG定量检测.