Detection of Plasmodium vivax using Automated Hematology Analyzer in the Korean Army.

BACKGROUND: This study aimed to evaluate whether our equation model developed from the Sysmex hematology analyzer can discriminate patients with Plasmodium vivax (P. vivax) infection from those with acute febrile illness (AFI) and healthy controls. Besides, we compared our model with the previously studied models. METHODS: A total of 312 blood samples were collected from the P. vivax, AFI, and healthy control groups. All samples were tested for routine complete blood count conducted by using a Sysmex XE-2100 or XE-5000 analyzer. We compared the reportable and research parameters generated from the Sysmex analyzer among the three groups. The selected parameters that showed a significant difference between the P. vivax and the other group were included in the logistic regression analysis to develop our model (N-OIpv model). Moreover, we analyzed the CBC data according to the previous models, such as the presence of abnormal blue coded events in the WBC/BASO scattergram called the observer-interpretation (OIpv) model, and the previous equation model (N-OD1pv model) developed by Campuzano-Zuluaga et al. Results: The N-OIpv model, which consists of three parameters, such as mean cell volume, plateletcrit, and Lymph-X, showed the best performance for detection of malaria (97.4% accuracy). Also, this model can increase the sensitivity by about 11.9% to 18.1% compared with the OIpv and N-OD1pv models, respectively. CONCLUSIONS: We concluded that the N-OIpv model using the Sysmex hematology analyzer is a useful diagnostic tool in the routine laboratory workup for malaria.

Fluorescence in situ hybridization panel for monitoring of minimal residual disease in patients with double minute chromosomes.

A double minute chromosome (dmin) is a small fragment of extrachromosomal DNA bearing amplified genes observed in malignancies. We investigated the incidence and characteristics of dmins in hematologic malignancies, and the quantitative changes during the treatment follow-up. Once a dmin was observed in conventional G-banding, it was characterized using fluorescence in situ hybridization (FISH) with the panel of MYC, NMYC, and MLL probes. Quantitative changes of malignant cells were measured using G-banding and FISH during the follow up. Dmins were observed in 1.23% of patients (6/489) at the initial diagnosis including 4 with MYC amplification, 1 with MLL and 1 with NMYC. All 6 had complex karyotypes and showed short overall survival (7.7 months). In follow-up specimens, FISH detected dmins in 11 cases out of which G-banding detected dmins in 9 cases. The number of dmins detected by FISH and G-banding did not correlate well. Amplification of NMYC in dmins is reported for the first time. A FISH panel composed of frequently amplified oncogenes (MYC, NMYC, and MLL) in dmins is useful for characterization of dmins. FISH is a sensitive method in detecting dmins and will be useful in monitoring of the minimal residual disease.

Performance evaluation of enzyme immunoassay for voriconazole therapeutic drug monitoring with automated clinical chemistry analyzers.

OBJECTIVE: Voriconazole is a triazole antifungal developed for the treatment of fungal infectious disease, and the clinical utility of its therapeutic drug monitoring has been evaluated. Recently, a new assay for analyzing the serum voriconazole concentration with an automated clinical chemistry analyzer was developed. We evaluated the performance of the new assay based on standardized protocols. METHODS: The analytical performance of the assay was evaluated according to its precision, trueness by recovery, limit of quantitation, linearity, and correlation with results from liquid chromatography-tandem mass spectrometry (LC-MS/MS). The evaluation was performed with the same protocol on two different routine chemistry analyzers. All evaluations were performed according to CLSI Guidelines EP15, EP17, EP6, and EP9 [1-4]. RESULTS: Coefficients of variation for within-run and between-day imprecision were 3.2-5.1% and 1.5-3.0%, respectively, on the two different analyzers for pooled serum samples. The recovery rates were in the range of 95.4-102.2%. The limit of blank was 0.0049 µg/mL, and the limit of detection of the samples was 0.0266-0.0376 µg/mL. The percent recovery at three LoQ levels were 67.9-74.6% for 0.50 µg/mL, 75.5-80.2% for 0.60 µg/mL, and 89.9-96.6% for 0.70 µg/mL. A linear relationship was demonstrated between 0.5 µg/mL and 16.0 µg/mL (R2 =0.9995-0.9998). The assay correlated well with LC-MS/MS results (R2 =0.9739-0.9828). CONCLUSIONS: The assay showed acceptable precision, trueness, linearity, and limit of quantification, and correlated well with LC-MS/MS. Therefore, its analytical performance is satisfactory for monitoring the drug concentration of voriconazole.

Quantification of human plasma-busulfan concentration by liquid chromatography-tandem mass spectrometry.

BACKGROUND: Busulfan, an alkylating agent administered prior to hematopoietic stem cell transplantation, has a narrow therapeutic range and wide variability in metabolism. We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for rapid and accurate quantification of plasma busulfan. METHODS: Busulfan was separated and detected using an LC system containing a C18 column equipped with MS/MS. The sample was eluted with a mobile phase gradient for a total run time of 10 min. Plasma busulfan concentration was quantified against a 6-point standard curve in a multiple reaction monitoring mode at mass-to-charge (m/z) 264.1 > 151.1. Precision, recovery, matrix effect, linearity, detection capability, carryover, and stability were evaluated. The range of plasma busulfan concentration was obtained by analyzing samples from 9 children receiving busulfan. RESULTS: The coefficients of variation of within-run and within-laboratory precision were all below 5%. Recoveries were all within the range of 100-105%. Linearity was verified from 0 to 5,000 ng/mL. Limit of detection and limit of quantification were 1.56 and 25 ng/mL, respectively. Carryover rate was within allowable limits. Plasma busulfan concentration was stable for 2 weeks at -20℃ and -80℃, but decreased by 25% when the plasma was stored for 24 hr at room temperature, and by <5% in 24 hr at 4℃. The plasma busulfan concentrations were between 347 ng/mL and 5,076 ng/mL. CONCLUSIONS: Our method using LC-MS/MS enables highly accurate, reproducible, and rapid busulfan monitoring with minimal sample preparation. The method may also enable safe and proper dosage.

Identification of two novel NPM1 mutations in patients with acute myeloid leukemia.

BACKGROUND: Genetic abnormalities in adult AML are caused most frequently by somatic mutations in exon 12 of the NPM1 gene, which is observed in approximately 35% of AML patients and up to 60% of patients with cytogenetically normal AML (CN-AML). METHODS: We performed mutational analysis, including fragment analysis and direct sequencing of exon 12 of the NPM1 gene, on 83 AML patients to characterize the NPM1 mutations completely. RESULTS: In this study, NPM1 mutations were identified in 19 (22.9%) of the 83 AML patients and in 12 (42.9%) of the 28 CN-AML patients. Among the 19 patients with NPM1 mutations, type A NPM1 mutations were identified in 16 (84.2%) patients, whereas non-A type NPM1 mutations were observed in 3 (15.8%) patients. Two of the 3 non-A type NPM1 mutations were novel: c.867_868insAAAC and c.869_873indelCTTTAGCCC. These 2 novel mutant proteins display a nuclear export signal motif (L-xxx-L-xx-V-x-L) less frequently and exhibit a mutation at tryptophan 290 that disrupts the nucleolar localization signal. CONCLUSIONS: This study suggests that novel NPM1 mutations may be non-rare and that supplementary sequence analysis is needed along with conventional targeted mutational analysis to detect non-A types of NPM1 mutations.

First Korean case of Robinsoniella peoriensis bacteremia in a patient with aspiration pneumonia.

Robinsoniella peoriensis has recently been identified as a Gram-positive, spore-forming, anaerobic rod originally recovered from swine manure storage pits. To date, 6 cases of R. peoriensis infection have been reported, including 2 cases of bacteremia, 1 of abdominal fluid collection, and 3 of wound infection. In the present study, we report a 76-yr-old man with R. peoriensis bacteremia who developed aspiration pneumonia. Gram staining of a purified colony revealed Gram-positive, rod-shaped bacteria. Biochemical identification using API 20 A (bioMérieux, France) indicated presence of Clostridium spp. We performed both 500-bp and full-gene sequencing of 16S rRNA of the isolate. The sequence was analyzed with MicroSeq ID 16S rRNA Library v2.0 (Applied Biosystems, USA), GenBank Basic Local Alignment Search Tool (BLAST) (http://www.ncbi.nlm.nih.gov/genbank), and EzTaxon database v2.1 (http://www.eztaxon.org). The 500-bp 16S rRNA sequence of the blood culture isolate showed 99.16-99.79% similarity with R. peoriensis and the full-gene 16S rRNA sequence showed 98.87-99.50% similarity with R. peoriensis. The organism was confirmed as R. peoriensis by using all of the mentioned databases except for MicroSeq, which did not include the RNA sequence of this bacterium. This case suggests that identification of R. peoriensis might be challenging in clinical laboratories with no access to molecular methods, as certain commercial identification systems may not identify, or may misidentify, this organism. To the best of our knowledge, this is the first report of the isolation of R. peoriensis in Korea.

The first study on nucleotide-level identification of Hb Koriyama in a patient with severe hemolytic anemia.

Hereditary hemolytic anemia comprises a group of disorders in which red blood cells are destroyed faster than they are produced in the bone marrow; various hereditary factors can cause this condition, including production of defective Hb and erythrocyte membrane. Recently, we identified Hb Koriyama, a rare Hb variant that was undetectable in Hb electrophoresis and stability tests, in a patient with severe hemolytic anemia. This is the first study to show the nucleotide-level sequence variations in Hb Koriyama. On the basis of our results, we conclude that unstable Hb may not be detectable by conventional Hb electrophoresis or stability tests. Thus, we suggest further genetic workup in cases of unexplained hereditary hemolytic anemia.