Impact of Academia-Government Collaboration on Laboratory Medicine Standardization in South Korea: analysis of eight years creatinine proficiency testing experience.

OBJECTIVES: To evaluate the performance of the Academia-Government Collaboration for Laboratory Medicine Standardization in Korea (KR-STDZN) based on data from KR-STDZN proficiency testing (KR-STDZN-PT) for creatinine over eight years (2015-2022). METHODS: We used KR-STDZN-PT data of creatinine tests from 2015 to 2022. Acceptance of the participating institutions' test results was assessed by calculating the acceptance performance as absolute bias (absBias%), total coefficient of variance (tCV%), and total error (TE%) for each sample using six measurements from each institution and true values of each reference material. The test result was considered acceptable when absBias%, tCV%, and TE% were <5.10, <3.20, and <11.40 %, respectively. The proportion of acceptable institutions among all participating institutions in each round was defined as the acceptance rate. Improvements in absBias%, tCV%, and TE% were analyzed using creatinine concentration ranges in samples. RESULTS: The number of participating institutions increased from 2015 to 2017 but remained consistent since 2018. The acceptance rates for absBias% and TE% increased from 52.2 and 77.6 %, in 2015 and to 90.7 and 96.3 %, in 2022, respectively. The acceptance rate for tCV% remained in the 90 % range for eight years. When creatinine <3 mg/dL, mean absBias%, and mean TE% improved significantly in 2021-2022 compared to 2015-2016 (p<0.05). When creatinine >3 mg/dL, acceptance performance did not improve. Mean tCV% remained consistent annually regardless of creatinine concentration. No significant variations in test methods were observed. CONCLUSIONS: The collaboration between academia and the government improved creatinine testing quality. Nevertheless, KR-STDZN must be expanded and refined.

Cross-Activation of Regulatory T Cells by Self Antigens Limits Self-Reactive and Activated CD8+ T Cell Responses.

The interaction between regulatory T (Treg) cells and self-reactive T cells is a crucial mechanism for maintaining immune tolerance. In this study, we investigated the cross-activation of Treg cells by self-antigens and its impact on self-reactive CD8+ T cell responses, with a focus on the P53 signaling pathway. We discovered that major histocompatibility complex (MHC) I-restricted self-peptides not only activated CD8+ T cells but also induced the delayed proliferation of Treg cells. Following HLA-A*0201-restricted Melan-A-specific (pMelan) CD8+ T cells, we observed the direct expansion of Treg cells and concurrent suppression of pMelan+CD8+ T cell proliferation upon stimulation with Melan-A peptide. Transcriptome analysis revealed no significant alterations in specific signaling pathways in pMelan+CD8+ T cells that were co-cultured with activated Treg cells. However, there was a noticeable upregulation of genes involved in P53 accumulation, a critical regulator of cell survival and apoptosis. Consistent with such observation, the blockade of P53 induced a continuous proliferation of pMelan+CD8+ T cells. The concurrent stimulation of Treg cells through self-reactive TCRs by self-antigens provides insights into the immune system's ability to control activated self-reactive CD8+ T cells as part of peripheral tolerance, highlighting the intricate interplay between Treg cells and CD8+ T cells and implicating therapeutic interventions in autoimmune diseases and cancer immunotherapy.

Cardiovascular Collapse after the Induction of Anesthesia Due to the MASS Effect of Unruptured Giant Bullae.

Background and Objectives: Giant bullae rupture easily and cause tension pneumothorax, which can cause problems during general anesthesia. However, the hemodynamic instability that can occur due to the mass effect of an unruptured giant bulla should not be overlooked. Case report: A 43-year-old male patient visited the emergency room with an abdominal wound. There was a giant emphysematous bulla in the left lung. Emergency surgery was decided upon because there was active bleeding according to abdominal CT. After tracheal intubation, the patient's blood pressure and pulse rate dramatically decreased. His blood pressure did not recover despite the use of vasopressors and discontinuation of positive pressure ventilation applied to the lungs. Thus, a bullectomy was immediately performed. The patient's blood pressure and pulse rate were normalized after the bullectomy. Conclusions: If emergency surgery under general anesthesia is required in a patient with a giant emphysematous bulla, it is safe to minimize positive pressure ventilation and remove the giant emphysematous bulla as soon as possible before proceeding with the remainder of the surgery. Tension pneumothorax due to the rupturing of a bulla should be considered first. However, hemodynamic changes might occur due to the mass effect caused by a giant bulla.

Revisiting glomerular hyperfiltration and examining the concept of high dietary protein-related nephropathy in athletes and bodybuilders.

PURPOSE OF REVIEW: High-protein diets (HPDs) are popular but their consequences for kidney health, especially among athletes and bodybuilders who typically maintain a high protein intake for a long time, have not been investigated. This review focused on recent studies of the association of HPD with long-term kidney health and the concept of high dietary protein-related nephropathy. RECENT FINDINGS: Several long-term observational studies including large populations have reinforced the notion that HPDs are associated with a rapid decline of kidney function. An increase in renal blood flow and glomerular hyperfiltration caused by vasodilation, and increased levels of endocrine and paracrine factors (glucagon, IGF-1, prostanoids, and nitric oxide), facilitates the excretion of protein-derived nitrogenous waste. Inhibition of tubule-glomerular feedback and increased proximal tubular Na+ reabsorption after a HPD augment glomerular hyperfiltration and may trigger synthesis of proinflammatory cytokines and receptor for advanced glycation end-products (RAGE). Focal segmental glomerulosclerosis reported in association with anabolic steroid may indeed be a HPD nephropathy given that HPD results in progressive glomerulosclerosis, especially in remnant glomeruli or in diabetic kidney disease but can happen in any high-risk situation, such as solitary kidney and polycystic kidneys. SUMMARY: HPD among athletes and bodybuilders in an extreme way across a long-term period may pose a risk to renal health including high incidence of HPD nephropathy.

A ZBTB16-RARα Variant of Acute Promyelocytic Leukemia with Concurrent Myeloid Sarcoma Presenting as Sudden Onset Paraplegia.

BACKGROUND: The co-occurrence of myeloid sarcoma (MS) and acute promyelocytic leukemia (APL) is a rare clinical event. METHODS: A 56-year-old man presented with lower extremity paralysis that occurred 6 hours before admission. Magnetic resonance imaging revealed an epidural mass. RESULTS: Histopathological examination demonstrated an extramedullary myeloid malignancy. Bone marrow examination showed abnormal promyelocytes and dysplasia, and an immunophenotyping study indicated very strong myeloperoxidase activity, suggesting APL. CONCLUSIONS: The final diagnosis given was spinal MS with a ZBTB16-RARα variant of APL. The possibility that patients with rapidly progressive neurologic symptoms could have MS and concurrent APL should be considered.

Comparison of Four Swab and Transport Media Combinations for the Detection of Respiratory Viruses.

BACKGROUND: We compared four combinations of nasopharyngeal swabs and transport media for their ability to transfer and recover viruses under different storage conditions. METHODS: Each swab was immersed in culture supernatants of influenza A virus (IAV), respiratory syncytial virus, and adenovirus, placed in transport medium, and stored at -20℃, +4℃, +20 to 25℃, and +37℃ for 5 days. On each day, virus culture and real-time PCR were performed for each virus. RESULTS: All samples under different storage conditions showed positive results up to 5 days using both virus culture and real-time PCR. Real-time PCR showed that samples stored at -20℃, 4℃, and 20 - 25℃ were within two cycle thresholds (Cts) up to 5 days, but IAV at 37℃ showed that viral titer decreased after 3 days. CONCLUSIONS: Our results indicate that these swab and transport media maintained the stability of the above viruses for 5 days at room temperature, refrigerated, and frozen storage conditions.

Waist-hip ratio measured by bioelectrical impedance analysis as a valuable predictor of chronic kidney disease development.

Obesity is a major health problem worldwide and is associated with chronic kidney disease (CKD). Body mass index (BMI) is a common method of diagnosing obesity, but there are concerns about its accuracy and ability to measure body composition. This study evaluated the risk of CKD development in a middle-aged population in association with various body composition metrics. From a prospective cohort of 10,030 middle-aged adults, we enrolled 6727 for whom baseline and follow-up data were available. We collected data pertaining to participants' BMI, manually measured waist-hip ratio (WHR), and various measurements of bioelectrical impedance analysis (BIA), including total body fat content, muscle content, and calculated WHR, and classified the participants into quintiles accordingly. CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 in follow-up laboratory tests. While an increase in BMI, WHR, and total body fat were associated with an elevated risk of CKD, an increase in total body muscle decreased the risk. Among the body composition metrics, WHR measured by BIA had the highest predictive value for CKD (C-statistics: 0.615). In addition, participants who were "healthy overweight, (defined as low WHR but high BMI), exhibited a 62% lower risk of developing CKD compared to those with "normal-weight obesity," (defined as high WHR despite a normal BMI). In conclusion, we suggest that central obesity measured by BIA is a more accurate indicator than BMI for predicting the development of CKD.

The Roles and Associated Mechanisms of Adipokines in Development of Metabolic Syndrome.

Metabolic syndrome is a cluster of metabolic indicators that increase the risk of diabetes and cardiovascular diseases. Visceral obesity and factors derived from altered adipose tissue, adipokines, play critical roles in the development of metabolic syndrome. Although the adipokines leptin and adiponectin improve insulin sensitivity, others contribute to the development of glucose intolerance, including visfatin, fetuin-A, resistin, and plasminogen activator inhibitor-1 (PAI-1). Leptin and adiponectin increase fatty acid oxidation, prevent foam cell formation, and improve lipid metabolism, while visfatin, fetuin-A, PAI-1, and resistin have pro-atherogenic properties. In this review, we briefly summarize the role of various adipokines in the development of metabolic syndrome, focusing on glucose homeostasis and lipid metabolism.

Comparing Results of Five SARS-CoV-2 Antibody Assays Before and After the First Dose of ChAdOx1 nCoV-19 Vaccine among Health Care Workers.

Reliable results regarding serologic positivity for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody before and after AstraZeneca (AZ) vaccination are essential for estimating the efficacy of vaccination. We assessed positivity rates and associated factors using five SARS-CoV-2 antibody assays. A total of 228 paired serum samples (456 samples) were obtained from 228 participants. After baseline sampling, the second sampling was conducted between 11 and 28 days after the first dose of the AZ vaccine. Sera were tested using five SARS-CoV-2 antibody assays, including two surrogate virus neutralization tests. A questionnaire on the symptoms, severity, and duration of adverse reactions was completed by all participants. The overall positivity rates for SARS-CoV-2 antibody were 84.6% for the Roche assay, 92.5% for the Abbott assay, 75.4% for the Siemens assay, 90.7% for the SD Biosensor assay, and 66.2% for the GenScript assay after the first dose of the AZ vaccine. The positivity rates and antibody titers of sera obtained between 21 and 28 days were significantly higher than those obtained between 11 and 20 days in all five assays. More-severe adverse reactions and longer durations of adverse reactions were related to higher SARS-CoV-2 antibody levels. The agreements and correlations among the assays applied were substantial (к, 0.73 to 0.95) and strong (ρ, 0.83 to 0.91). A single dose of the AZ vaccine led to high positivity rates based on the five assays. Days after vaccination and adverse reactions could help estimate serologic conversion rates. The results should be interpreted cautiously considering the assays and cutoffs applied. Our findings could inform decisions regarding vaccination and laboratory settings and could thus contribute to the control of the spread of SARS-CoV-2 infection.

Comparison of the Results of Five SARS-CoV-2 Antibody Assays before and after the First and Second ChAdOx1 nCoV-19 Vaccinations among Health Care Workers: a Prospective Multicenter Study.

Reliable results for serological positivity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody after the second dose of AstraZeneca (AZ) vaccination are important to estimate the real efficacy of vaccination. We evaluated positivity rates and changes in semiquantitative antibody titers before and after the first and second ChAdOx1 nCoV-19 vaccinations using five SARS-CoV-2 antibody assays, including two surrogate virus neutralization tests. A total of 674 serum samples were obtained from 228 participants during three blood sampling periods. A questionnaire on symptoms, severity, and adverse reaction duration was completed by participants after the second vaccination. The overall positive rates for all assays were 0.0 to 0.9% before vaccination, 66.2 to 92.5% after the first vaccination, and 98.2 to 100.0% after the second vaccination. Median antibody titers in five assays after the second dose of vaccination were increased compared to those after the first dose (106.4-fold increase for Roche total antibody, 3.6-fold for Abbott IgG, 3.6-fold for Siemens, 1.2-fold for SD Biosensor V1 neutralizing antibody, and 2.2-fold for GenScript neutralizing antibody). Adverse reactions were reduced after the second dose in 89.9% of participants compared to after the first dose. Overall, the second vaccination led to almost 100% positivity rates based on these SARS-CoV-2 antibody assays. The results should be interpreted with caution, considering the characteristics of the applied assays. Our findings could inform decisions regarding vaccination and the use of immunoassays, thus contributing to SARS-CoV-2 pandemic control.

Semiquantitative Analysis of the Results of an Image-Based Urine Sediment Analyzer Considering the Preanalytical Factors.

BACKGROUND: Automated microscopic platforms are increasingly used in clinical laboratories for rapid analysis of samples. However, it is important to present the results quantitatively or semiquantitatively because automated platforms use various technologies for analysis as well as different sediment preparation methods. The results of cell counting using an on screen image review program for the cobas u 701 analyzer (Roche Diagnostics Interna-tional, Rotkreuz, Switzerland) differed from those obtained by manual microscopic examination (MME). This study was performed to investigate the difference of results among analyzer, on-screen image review and MME. METHODS: Freshly collected urine specimens from outpatients were used. We calculated the mean, standard deviation, and 95% confidence interval for red and white blood cell (RBC/WBC) quantitative results obtained using the cobas u 701 analyzer. These results were compared to those obtained by manual counting. RBC and WBC counts determined with the cobas u 701 analyzer were compared to those obtained by MME per unit field. RESULTS: The semiquantitative results of MME were graded as 0 - 2, 3 - 5, 6 - 10, 11 - 20, 21 - 30, and many or numerous cells/high power field (HPF). The RBC and WBC counts determined by image analyses showed the tendency to be one grade higher than those from MME in the range of 3 to 5/HPF to many/HPF. The results of nearly all samples with 0 - 2/HPF and numerous/HPF for RBC and WBC counts were consistent with the grade found by MME. CONCLUSIONS: The one-grade difference may have been caused by the differences of preanalytical factors in the sample volume, centrifugal force, urine concentration ratio, or sediment volume/area of the slide. When reporting the results of image analyses, RBC and WBC counts should be raised by one grade to compensate for MME. Each laboratory needs to verify the on-screen review of images corresponding to the microscopic field of view according to the clinical laboratory's specific preanalytical practices.

Zinc finger proteins orchestrate active gene silencing during embryonic stem cell differentiation.

Transcription factors and chromatin remodeling proteins control the transcriptional variability for ESC lineage commitment. During ESC differentiation, chromatin modifiers are recruited to the regulatory regions by transcription factors, thereby activating the lineage-specific genes or silencing the transcription of active ESC genes. However, the underlying mechanisms that link transcription factors to exit from pluripotency are yet to be identified. In this study, we show that the Ctbp2-interacting zinc finger proteins, Zfp217 and Zfp516, function as linkers for the chromatin regulators during ESC differentiation. CRISPR-Cas9-mediated knock-outs of both Zfp217 and Zfp516 in ESCs prevent the exit from pluripotency. Both zinc finger proteins regulate the Ctbp2-mediated recruitment of the NuRD complex and polycomb repressive complex 2 (PRC2) to active ESC genes, subsequently switching the H3K27ac to H3K27me3 during ESC differentiation for active gene silencing. We therefore suggest that some zinc finger proteins orchestrate to control the concise epigenetic states on active ESC genes during differentiation, resulting in natural lineage commitment.

Cyclin-dependent kinase 1 activity coordinates the chromatin associated state of Oct4 during cell cycle in embryonic stem cells.

Cyclin-dependent kinase 1 (Cdk1) is indispensable for embryonic stem cell (ESC) maintenance and embryo development. Even though some reports have described a connection between Cdk1 and Oct4, there is no evidence that Cdk1 activity is directly linked to the ESC pluripotency transcription program. We recently reported that Aurkb/PP1-mediated Oct4 resetting is important to cell cycle maintenance and pluripotency in mouse ESCs (mESCs). In this study, we show that Cdk1 is an upstream regulator of the Oct4 phosphorylation state during cell cycle progression, and it coordinates the chromatin associated state of Oct4 for pluripotency-related gene expression within the cell cycle. Upon entry into mitosis, Aurkb in the chromosome passenger complex becomes fully activated and PP1 activity is inhibited downstream of Cdk1 activation, leading to sustaining Oct4(S229) phosphorylation and dissociation of Oct4 from chromatin during the mitotic phase. Cdk1 inhibition at the mitotic phase abnormally results in Oct4 dephosphorylation, chromosome decondensation and chromatin association of Oct4, even in replicated chromosome. Our study results suggest a molecular mechanism by which Cdk1 directly links the cell cycle to the pluripotency transcription program in mESCs.

Long non-coding RNA ChRO1 facilitates ATRX/DAXX-dependent H3.3 deposition for transcription-associated heterochromatin reorganization.

Constitutive heterochromatin undergoes a dynamic clustering and spatial reorganization during myogenic differentiation. However the detailed mechanisms and its role in cell differentiation remain largely elusive. Here, we report the identification of a muscle-specific long non-coding RNA, ChRO1, involved in constitutive heterochromatin reorganization. ChRO1 is induced during terminal differentiation of myoblasts, and is specifically localized to the chromocenters in myotubes. ChRO1 is required for efficient cell differentiation, with global impacts on gene expression. It influences DNA methylation and chromatin compaction at peri/centromeric regions. Inhibition of ChRO1 leads to defects in the spatial fusion of chromocenters, and mislocalization of H4K20 trimethylation, Suv420H2, HP1, MeCP2 and cohesin. In particular, ChRO1 specifically associates with ATRX/DAXX/H3.3 complex at chromocenters to promote H3.3 incorporation and transcriptional induction of satellite repeats, which is essential for chromocenter clustering. Thus, our results unveil a mechanism involving a lncRNA that plays a role in large-scale heterochromatin reorganization and cell differentiation.

An ensemble approach of urine sediment image analysis and NMP22 test for detection of bladder cancer cells.

BACKGROUND: Bladder cancer is the eighth most common cancer and the second most common urological cancer in Korean males. Current diagnostic tools for bladder cancer include cystoscopy (an upper tract study), urine cytology, and nuclear matrix protein 22 (NMP22) test. In this study, we evaluated the detection rate of atypical/malignant urothelial cells in urinary sediment images when flagged for positive NMP22 test. METHODS: NMP22 was measured by NMP22 BladderChek Test (Abbott Laboratories) and urine chemical and sediment analysis were performed by fully automated cobas 6500 urine analyzer (Roche Diagnostics). Specimens that met the manual microscopic examination (MME) criteria were then subjected to an on-screen review of images. We subsequently reviewed sediment images and examined under the microscopy for the flagged cases. RESULTS: Of the 1217 patients, 345 (28.3%) had positive NMP22 results, whereas 872 (71.7%) had negative results. Out of the positive results, 154 (12.7%) were positive and 191 (15.7%) weakly positive for NMP22. Screened review of flagged specimens (ie, positive NMP22 result) with sediment imaging analysis revealed that suspicious urothelial carcinoma cells were detected in only two cases (0.8%). In the NMP22 negative flagged cases, the suspicious neoplastic cells were not found. CONCLUSIONS: Our findings suggest that the NMP22 test should be added to the flagging criteria for MME to improve diagnostic accuracy. The combination of urine sediment imaging analysis and NMP22 test can significantly assist technicians in the review of specimens.

Application and optimization of reference change values for Delta Checks in clinical laboratory.

BACKGROUND: Delta check is a patient-based QC tool for detecting errors by comparing current and previous test results of patient. Reference change value (RCV) is adopted in guidelines as method for delta check, but the performance is not verified. We applied RCV-based delta check method to patients' data and modified for application. MATERIALS AND METHODS: Reference change value were calculated using results of internal QC materials and biological variation data. Test results of 17 analytes in inpatients, outpatients, and health examination recipients were collected. The detection rates of currently used delta check method and those of RCV-based method were compared, and the methods were modified. RESULTS: Reference change value-based method had higher detection rates compared to conventional method. Applied modifications reduced detection rates. Removing the pairs of results within reference interval reduced detection rates (0.42% ~ 10.92%). When RCV was divided by time interval, the detection rates were similar to prior rates in outpatients (0.19% ~ 1.34%). Using RCV multiplied by twice the upper limit of reference value as cutoff reduced the detection rate (0.07% ~ 1.58%). CONCLUSIONS: Reference change value is a robust criterion for delta check and included in clinical laboratory practice guideline. However, RCV-based method generates high detection rates which increase workload. It needs modification for use in clinical laboratories.

Performance evaluation of commercial library construction kits for PCR-based targeted sequencing using a unique molecular identifier.

BACKGROUND: Target enrichment is a critical component of targeted deep next-generation sequencing for the cost-effective and sensitive detection of mutations, which is predominantly performed by either hybrid selection or PCR. Despite the advantages of efficient enrichment, PCR-based methods preclude the identification of PCR duplicates and their subsequent removal. Recently, this limitation was overcome by assigning a unique molecular identifier(UMI) to each template molecule. Currently, several commercial library construction kits based on PCR enrichment are available for UMIs, but there have been no systematic studies to compare their performances. In this study, we evaluated and compared the performances of five commercial library kits from four vendors: the Archer® Reveal ctDNA™ 28 Kit, NEBNext Direct® Cancer HotSpot Panel, Nugen Ovation® Custom Target Enrichment System, Qiagen Human Comprehensive Cancer Panel(HCCP), and Qiagen Human Actionable Solid Tumor Panel(HASTP). RESULTS: We evaluated and compared the performances of the five kits using 50 ng of genomic DNA for the library construction in terms of the library complexity, coverage uniformity, and errors in the UMIs. While the duplicate rates for all kits were dramatically decreased by identifying unique molecules with UMIs, the Qiagen HASTP achieved the highest library complexity based on the depth of unique coverage indicating superb library construction efficiency. Regarding the coverage uniformity, the kits from Nugen and NEB performed the best followed by the kits from Qiagen. We also analyzed the UMIs, including errors, which allowed us to adjust the depth of unique coverage and the length required for sufficient complexity. Based on these comparisons, we selected the Qiagen HASTP for further performance evaluations. The targeted deep sequencing method based on PCR target enrichment combined with UMI tagging sensitively detected mutations present at a frequency as low as 1% using 6.25 ng of human genomic DNA as the starting material. CONCLUSION: This study is the first systematic evaluation of commercial library construction kits for PCR-based targeted deep sequencing utilizing UMIs. Because the kits displayed significant variability in different quality metrics, our study offers a practical guideline for researchers to choose appropriate options for PCR-based targeted sequencing and useful benchmark data for evaluating new kits.

Abundance of C-terminal binding protein isoform is a prerequisite for exit from pluripotency in mouse embryonic stem cells.

Unlike lower organisms, mammals have 2 C-terminal binding protein (Ctbp) isoforms, Ctbp1 and Ctbp2. Ctbp2 is revealed as a key factor involved in determining cell fate decisions by regulating the epigenetic state in active embryonic stem cell (ESC) genes. However, the molecular mechanism underlying how Ctbp1 and Ctbp2 have different roles remains elusive. Here we demonstrate that Ctbp isoform abundance is important for mouse embryonic ESCs (mESCs) to exit from pluripotency. Temporal expression patterns of Ctbp isoforms were quite different; Ctbp2 is more highly expressed in mESCs and decreases during differentiation, while Ctbp1 is constantly expressed at a lower level. Ctbp2 knockdown, but not Ctbp1 knockdown, in mESCs resulted in impaired exit from pluripotency. Interestingly, Ctbp1 and Ctbp2 overexpression in Ctbp2-knockdown mESCs leads to exiting from pluripotency in a manner similar to that of wild-type mESCs. Quantification of Ctbp1 and Ctbp2 revealed that differentiation ability correlates with abundance of Ctbp isoform in undifferentiated mESCs, suggesting that a sufficient amount of Ctbp isoform is a prerequisite for exiting from pluripotency. The results support the contention that 2 redundant Ctbp isoforms regulate elaborate differentiation via temporally distinctive regulatory patterns in mESCs.-Suh, M. Y., Kim, T. W., Lee, H.-T., Shin, J., Kim, J.-H., Jang, H., Kim, H. J., Kim, S.-T., Cho, E.-J., Youn, H.-D. Abundance of C-terminal binding protein isoform is a prerequisite for exit from pluripotency in mouse embryonic stem cells.

Accuracy evaluation of Roche and Siemens tacrolimus and cyclosporine assays in comparison with liquid chromatography-tandem mass spectrometry.

Therapeutic drug monitoring of tacrolimus and cyclosporine is crucial to the success of organ transplantation. We evaluated the analytical performances and accuracy of two commercially available tacrolimus and cyclosporine assays (Roche ISD and Siemens) in comparison with liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 342 leftover whole blood samples requested for tacrolimus or cyclosporine assays were stored at -20 °C until analysis. Repeatability and between-run imprecision were evaluated using quality control materials provided by the manufacturer. Ring trial samples were used for the assessment of recovery. The results of the Roche ISD assay were compared with those of Siemens tacrolimus and cyclosporine assays and LC-MS/MS. Repeatability and between-run imprecision were 2.1-5.3% and 2.6-7.5%, respectively. Recovery of Roche ISD was 85.7 - 90.6% for cyclosporine and 96.2-98.5% for tacrolimus. The two immunoassays showed slight positive biases relative to LC-MS/MS for cyclosporine. For tacrolimus, Roche ISD produced virtually identical results to those of LC-MS/MS, whereas Siemens showed proportional differences, especially in patients receiving kidney transplantation. The analytical performances of Roche ISD were generally acceptable, especially regarding accuracy. Clinical laboratory staff should be aware of the strengths and weaknesses of commercial immunoassays in order to ensure accurate results.

Performance of the Dimension TAC assay and comparison of multiple platforms for the measurement of tacrolimus.

BACKGROUND: Therapeutic monitoring of tacrolimus is essential for reducing organ rejection and adverse effects. The measurement of tacrolimus in whole blood is taken by many automated platforms. We evaluated the analytical performance of the Dimension TAC assay, which is an upgraded reagent from the previous Dimension TACR assay. METHODS: The evaluations involved determination of precision, linearity, detection capability, and reagent lot-to-lot variability between three lot numbers. Correlation studies were conducted using the Dimension TACR assay, Architect, Elecsys assay, and MassTrak LC-MS/MS. RESULTS: The total coefficient of variation was below 10%. Acceptable linearity was observed in their respective reportable ranges. The limit of blank, limit of detection, and limit of quantification were 0.29, 0.47, and 0.81 ng/mL, respectively. Correlation analysis indicated that the Dimension TAC assay results were comparable to that of the Dimension TACR assay, Architect, and Elecsys results in liver and heart transplant patients. In kidney transplant patients, the Dimension TAC assay showed the poor correlation with Architect and Elecsys. The results from these assays were slightly higher than that of MassTrak. We found little lot-to-lot reagent variation among the reagents evaluated. CONCLUSION: The overall analytical performance of the Dimension TAC assay is acceptable for therapeutic monitoring in clinical practice. Our study that compared different platforms may provide some useful information regarding which test method to use.