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Objectives Free light chain (FLC) is used for the diagnosis and prediction with regard to the progression risk of plasma cell disorders and Freelite reagent using the SPAplus analyzer (The Binding Site) has been one of the widely used option. However, N Latex FLC reagent with the Atellica CH 930 analyzer (Siemens Healthineers) has shown the advantages of automation and high throughput. We aimed to evaluated clinical implication by differential analytical performances of two assays. Methods A total of 322 serum samples were collected from 193 patients requested for FLC analysis including 131 multiple myeloma patients. The precision, linearity, dilution recovery of N Latex FLC assay was evaluated. We compared the two assays and analyzed the monomer-dimer pattern for discrepant results. Results The precision, linearity, and dilution recovery performance was appropriate for the routine use in clinical laboratories. Despite the good correlation within normal range, proportional bias up-to 170% was observed in samples with high concentrations especially for lambda. The higher value samples with N Latex FLC assay contained more monomer forms than controls. All opposite changes of FLC burden by the N Latex FLC assay proved to present concordant dynamic changes when assessed by serum protein electrophoresis. Conclusions Clinical laboratories should be aware of the inter-assay variability of FLC quantitative measurements using different platforms, especially for high concentrations of both kappa and lambda measurements, possibly due to monomer/dimer ratio diversity. Clinical interpretations for multiple myeloma disease status might not be dramatically affected only when the same assay is utilized during follow-up periods.

Apolipoprotein monitoring is useful for diagnosing cardiovascular diseases, as they are risk factors of arteriosclerosis and other neutral fat-related diseases. LC-MS/MS is advantageous for simultaneous apolipoprotein quantification, differentiation, and standardization including their isoforms. However, fast and straightforward sample preparation that retains quantification accuracy remains challenging in clinical MS.We developed a simultaneous assay for serum apolipoprotein A-I, apolipoprotein B100 family, and apolipoprotein C-III using a high-throughput LC-MS/MS platform coupled with a BRAVO system. The assay was simplified by using sodium deoxycholate and trypsin/lys-C without reduction and alkylation steps.Simple sample preparation reduced turnaround time by 1.5 h and neat goat serum was chosen as an optimal calibration matrix for accurate protein quantification. Assay precision, linearity, correlation, accuracy, LOD, LLOQ, and carryover were validated according to CLSI guidelines over 41 days using more than 100 human serum samples. Good correlation compared with TIA was observed by Deming regression for all analytes.A high-throughput LC-MS/MS and BRAVO assay for simultaneous apolipoprotein analysis was validated using a simple preparation method with a human serum calibrator in goat serum matrix. The assay is readily expandable to include other target serum proteins and/or their isoforms. This article is protected by copyright. All rights reserved.

Context.— The N-terminal prohormone of the brain natriuretic peptide (NT-proBNP) is a major diagnostic biomarker for heart failure. Objective.— To compare the analytical and clinical performance of 3 NT-proBNP immunoassays: the Atellica IM NT-proBNP assay (Siemens Healthcare Diagnostics), the Alere NT-proBNP assay (Abbott Laboratories), and the Elecsys proBNP II assay (Roche Diagnostics). Design.— For the Atellica IM NT-proBNP assay, analytical performance, including precision, linearity, and carryover, was fully evaluated. Method comparisons among the 3 assays were performed using the Passing-Bablok regression and κ agreement test. To evaluate the clinical performance of the assays, 160 patient samples were used from patients with (n = 81) or without (n = 79) heart failure. Results.— The analytical performance of the Atellica IM NT-proBNP assay was acceptable according to the manufacturer's claims. The Atellica IM NT-proBNP assay showed a positive bias compared with the Elecsys proBNP II assay. The Cohen κ values among the 3 assays were satisfactory (>0.80) and comparable. There were no significant differences in areas under the curve. However, for the diagnosis of heart failure, the Elecsys proBNP II showed a higher specificity and positive likelihood ratio than the other assays. Conclusions.— All 3 NT-proBNP assays showed acceptable concordance, and their clinical performance was comparable. However, the Elecsys proBNP II might be a more discriminating NT-proBNP assay to diagnose heart failure.

For organ transplantation patients, the therapeutic drug monitoring (TDM) of immunosuppressive drugs is essential to prevent the toxicity or rejection of the organ. Currently, TDM is done by immunoassays or liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods; however, these methods lack specificity or are expensive, require high levels of skill, and offer limited sample throughput. Although matrix-assisted (MA) laser desorption ionization (LDI) mass spectrometry (MS) can provide enhanced throughput and cost-effectiveness, its application in TDM is limited due to the limitations of the matrixes such as a lack of sensitivity and reproducibility. Here, we present an alternative quantification method for the TDM of the immunosuppressive drugs in the blood of organ transplant patients by utilizing laser desorption ionization mass spectrometry (LDI-MS) based on a tungsten disulfide nanosheet, which is well-known for its excellent physicochemical properties such as a strong UV absorbance and high electron mobility. By adopting a microliquid inkjet printing system, a high-throughput analysis of the blood samples with enhanced sensitivity and reproducibility was achieved. Furthermore, up to 80 cases of patient samples were analyzed and the results were compared with those of LC-MS/MS by using Passing-Bablok regression and Bland-Altman analysis to demonstrate that our LDI-MS platform is suitable to replace current TDM techniques. Our approach will facilitate the rapid and accurate analysis of blood samples from a large number of patients for immunosuppressive drug prescriptions.

BackgroundWe aimed to suggest muscle mass-based criteria for using of the cystatin C test for the accurate estimated glomerular filtration rate (eGFR).Materials and methodsWe recruited 138 Korean subjects and evaluated eGFRcr (derived from Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) based on creatinine) was compared to eGFRcys based on cystatin C as the reference value. The skeletal muscle mass index (SMI) by bioelectrical impedance analysis (BIA) was used as representative of muscle mass. Calf circumference (CC) was also evaluated. We defined the patients by eGFRcr as those with values of eGFRcr ≥ 60 mL/min/1.73 m2 but eGFRcys < 60 mL/min/1.73 m2 as the detection of hidden renal impairment (DHRI). Cut-off values were determined based on muscle mass for the cases of DHRI suggesting the criteria of cystatin C test in renal function evaluation.ResultsWe confirmed significant negative correlation between %difference of eGFRcr from eGFRcys and SMI (r, −0.592 for male, −0.484 for female) or CC (r, −0.646 for male, −0.351 for female). SMI of 7.3 kg/m2 for males and 5.7 kg/m2 for females were suggested to be significant cutoffs for indication of cystatin C test. We also suggested CC would be valuable for cystatin C indication.ConclusionWe suggested the muscle mass-based objective criteria relating to SMI and CC that would indicate the use of cystatin C to evaluate renal function test in sarcopenic cases. Our results highlight the importance of muscle mass-based selection of renal function.

A ketogenic diet (KD) is known to have beneficial health effects. Various types of KD interventions have been applied to manage metabolic syndrome based on modification of diet parameters such as duration of intervention, macronutrient components, and total calories. Nevertheless, the beneficial health impact of isocaloric KD is largely unknown, especially in healthy subjects. The present study investigated the acute effects of a 3-day isocaloric KD. In this non-randomized intervention study, we recruited 15 healthy volunteers aged 24-38 years (7 men and 8 women) and placed them on an isocaloric KD restricting intake of carbohydrates but not energy (75% fat, 20% protein, 5% carbohydrate) for 3 days. Biochemical profiles and laboratory measurements were performed. Peripheral blood monocular cells were cultured, and measured cell stimulated cytokines. After short-term isocaloric KD, subjects lost body weight and serum free fatty acid levels were increased. These results accompanied elevated serum β-hydroxybutyrate (BHB) concentration and fibroblast growth factor 21 (FGF21) levels and improved insulin sensitivity. Regarding the direct effect of BHB on inflammasome activation, interleukin-1β (IL-1β) and tumor necrosis factor-α secretion in response to adenosine triphosphate or palmitate stimulation in human macrophages decreased significantly after isocaloric KD. In ex-vivo experiments with macrophages, both FGF21 and BHB further reduced IL-1β secretion compared to either BHB or FGF21 alone. The inhibitory effect of FGF21 on IL-1β secretion was blunted with bafilomycin treatment, which blocked autophagy flux. In conclusion, isocaloric KD for 3 days is a promising approach to improve metabolic and inflammatory status.Clinical Trial Registrationclinicaltrials.gov (NCT02964572).

Despite the superiority of non-HDL cholesterol (non-HDL-C) and apolipoprotein B (ApoB) as lipid markers for atherosclerotic cardiovascular disease (ASCVD), these are only suitable as secondary markers. We compared LDL cholesterol (LDL-C), non-HDL-C, and ApoB concentrations with respect to the occurrence of cardiovascular disease in adults enrolled in the Korean Genome and Epidemiology Study (KoGES).We used information on age; sex; medical history; family history of ASCVD; current lipid-lowering therapy; current smoking status; and creatinine, total cholesterol, HDL-C, LDL-C, triglyceride, and ApoB concentrations from 5,872 KoGES participants without ASCVD. New ASCVD development was monitored during the 8-year follow-up period. Adjusted hazard ratios (aHRs) for ASCVD of LDL-C, non-HDL-C, and ApoB concentrations were calculated based on the multivariate Cox regression analyses. The participants were also grouped as low and high according to the median values for each lipid marker, and calculated aHRs of each group combined by two lipid makers.ApoB showed the highest aHR per 1-SD for ASCVD (1.26; 95% confidence interval [CI], 1.11-1.43), followed by non-HDL-C (1.25; 95% CI, 1.11-1.41) and LDL-C (1.20; 95% CI, 1.06-1.37). The group with low LDL-C and high ApoB concentrations had a significantly higher aHR for ASCVD (1.61; 95% CI, 1.05-2.48) compared to the reference group values (low LDL-C and low ApoB concentrations). The aHR for the group with high LDL-C and low ApoB concentrations was not significant (1.30; 95% CI, 0.79-2.16).ApoB, non-HDL-C, and LDL-C are independent risk factors for ASCVD. Increases in the aHR per 1-SD for ASCVD were more strongly affected by ApoB, followed by non-HDL-C and LDL-C. Participants with low LDL-C and high ApoB concentrations showed increased ASCVD risk. For individuals with ASCVD risk factors, even those presenting normal LDL-C concentrations, measuring ApoB concentrations can provide useful information for better evaluation of ASCVD risk.

Accurate measurement of glycated hemoglobin (HbA1c) is crucial for a diabetes diagnosis and subsequent patient management. The detection method and presence of variant Hb can interfere with HbA1c measurements. We evaluated the HbA1c-measuring performance of the DxC 700 AU (Beckman Coulter, Brea, CA, USA) immunoassay-based device in comparison with another immunoassay device and the reference method.A total of 120 normal and 14 variant Hb samples were analyzed using the Cobas c 513 (Roche Diagnostics, Mannheim, Germany) and DxC 700 AU analyzers. Variant Hb samples were also analyzed using the reference method, along with 20 normal samples. The accuracy, precision, linearity, and carryover were determined.DxC 700 AU results strongly correlated with those of Cobas c 513 and exhibited accuracy in comparison with the reference method. The within-run, between-run, between-day, and total imprecision (%CV) values for the low- and high-concentration control materials were below 2%. The results of DxC 700 AU were linear over a wide HbA1c range (3.39%-18.30%). Although DxC 700 AU performed well in the presence of variant Hb, the HbA1c concentration was underestimated in the presence of fetal Hb. The possibility of interference from a high HbH proportion could not be ruled out.The overall analytical performance of DxC 700 AU was acceptable. The device is accurate, precise, and linear over a wide HbA1c concentration range. Although DxC 700 AU results highly correlated with those of Cobas c 513, caution should be exercised in cases of high HbF and HbH concentrations.

Quantitative analysis using laser desorption/ionization mass spectrometry (LDI-MS) has been limited because of the nonuniform distribution of analytes caused by the “coffee ring effect”. In this st...

Recently, the parylene-matrix chip was developed for quantitative analysis of small molecules less than 1 kDa. In this study, MALDI-TOF MS based on the parylene-matrix chip was performed to clinically diagnose intrahepatic cholangiocarcinoma (IHCC) and colorectal cancer (CRC). The parylene-matrix chip was applied for the detection of small cancer biomarkers, including N-methyl-2-pyridone-5-carboxamide (2PY), glutamine, lysophosphatidylcholine (LPC) 16:0, and LPC 18:0. The feasibility of MALDI-TOF MS based on the parylene-matrix chip was confirmed via analysis of spot-to-spot and shot-to-shot reproducibility. Serum metabolite markers of IHCC, N-methyl-2-pyridone-5-carboxamide (2PY), and glutamine were quantified using MALDI-TOF MS based on the parylene-matrix chip. For clinical diagnosis of CRC, two water-insoluble (barely soluble) biomarkers, lysophosphatidylcholine (LPC) 16:0 and LPC 18:0, were quantified. Finally, glutamine and LPC 16:0 were simultaneously detected at a range of concentrations in sera from colon cancer patients using the parylene-matrix chip. Thus, this method yielded high-throughput detection of cancer biomarkers for the mixture samples of water-soluble analytes (2PY and glutamine) and water-insoluble analytes (LPC 16:0 and LPC 18:0).

Background Automated cellular analyzers are expected to improve the analytical performance in body fluid (BF) analysis. We evaluated the analytical performance of three automated cellular analyzers and established optimum reflex analysis guidelines. Methods A total of 542 BF samples (88 cerebrospinal fluid [CSF] samples and 454 non-CSF samples) were examined using manual counting and three automated cellular analyzers: UniCel DxH 800 (Beckman Coulter), XN-350 (Sysmex), and UF-5000 (Sysmex). Additionally, 2,779 BF analysis results were retrospectively reviewed. For malignant cell analysis, the receiver operating characteristic (ROC) curve was used, and the detection of high fluorescence-BF cells (HF-BFs) using the XN-350 analyzer was compared with cytology results. Results All three analyzers showed good agreement for total nucleated cell (TNC) and red blood cell (RBC) counts, except for the RBC count in CSF samples using the UniCel DxH 800. However, variable degrees of differences were observed during differential cell counting. For malignant cell analysis, the area under the curve was 0.63 for the XN-350 analyzer and 0.76 for manual counting. We established our own reflex analysis guidelines as follows: HF-BFs 83.4/100 WBCs or eosinophils >3.8% are the criteria for mandatory double check confirmation with 1,000× magnification examination. Conclusions The three automated analyzers showed good analytical performances. Application of reflex analysis guidelines is recommended for eosinophils and HF-BFs, and manual confirmation is warranted.

Pediatric cancer patients undergoing chemotherapy or radiation therapy generally require a central venous catheter (CVC). However, serum drawn from CVCs has several drawbacks for use in routine chemistry tests. Biochemical analytes were evaluated using heparin plasma instead of serum to maintain turnaround time and to prevent problems caused by micro-clot formation or delayed clotting time.Venous blood samples from 52 pediatric oncology patients with chemoports or Hickman catheters were collected in serum separating tubes (SSTs) and lithium heparin tubes (LHTs). A total of 29 parameters were analyzed on a Cobas c702 (Roche Diagnostics, Mannheim, Germany). Passing-Bablok regression and Bland-Altman difference plots were used for statistical analyses.When the mean value of each analyte measured from LHT was compared with those from SST, percentage bias was within the desirable bias limit in most of the analytes. However, albumin, potassium, and inorganic phosphorus showed a negative constant bias of -3.0%, -5.3%, and -1.6%, respectively, and total protein showed a positive constant bias of + 3.8%.The use of LHTs for sample collection from pediatric patients with CVCs could be helpful for routine chemistry analyses. The results of potassium and total protein should be interpreted with consideration of the difference between serum and plasma samples.

Intracellular accumulation of mutant proteins causes proteinopathies, which lack targeted therapies. Autosomal dominant hearing loss (DFNA67) is caused by frameshift mutations in OSBPL2. Here, we show that DFNA67 is a toxic proteinopathy. Mutant OSBPL2 accumulated intracellularly and bound to macroautophagy/autophagy proteins. Consequently, its accumulation led to defective endolysosomal homeostasis and impaired autophagy. Transgenic mice expressing mutant OSBPL2 exhibited hearing loss, but osbpl2 knockout mice or transgenic mice expressing wild-type OSBPL2 did not. Rapamycin decreased the accumulation of mutant OSBPL2 and partially rescued hearing loss in mice. Rapamycin also partially improved hearing loss and tinnitus in individuals with DFNA67. Our findings indicate that dysfunctional autophagy is caused by mutant proteins in DFNA67; hence, we recommend rapamycin for DFNA67 treatment. Abbreviations: ABR: auditory brainstem response; ACTB: actin beta; CTSD: cathepsin D; dB: decibel; DFNA67: deafness non-syndromic autosomal dominant 67; DPOAE: distortion product otoacoustic emission; fs: frameshift; GFP: green fluorescent protein; HsQ53R-TG: human p.Q53Rfs*100-transgenic: HEK 293: human embryonic kidney 293; HFD: high-fat diet; KO: knockout; LAMP1: lysosomal associated membrane protein 1; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; NSHL: non-syndromic hearing loss; OHC: outer hair cells; OSBPL2: oxysterol binding protein-like 2; SEM: scanning electron microscopy; SGN: spiral ganglion neuron; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; TG: transgenic; WES: whole-exome sequencing; YUHL: Yonsei University Hearing Loss; WT: wild-type.

Patients with diabetes are required to lance their fingers daily for self-monitoring their blood glucose level. Patients might be reluctant to use commercial lancets with thick outer diameters due to lancing pain; this results in the worsening of their health. A metallic microneedle is an ideal substitute to the commercial lancet system and offers a minimally invasive and patient friendly approach for capillary blood extraction. However, reports regarding the performance of sufficient long and high stiffness microneedles for innocuous and efficient capillary blood sampling for conducting clinical trials are rare. Here, we developed a novel micro-lancet (ML) that is 3 mm long and has a 130 µm outer diameter and a sharp beveled 15° tip. ML induced lesser tissue damage than the commercial ACCU-CHEK Softclix in a porcine skin test. Through a clinical study, we demonstrated that the pain scores using the commercial lancet and ML were 3.4 and 0.8 the numeric pain rating scale, respectively. The average blood volume drawn using the ML was 0.96 µL, which satisfies the minimum requirement (0.3 µL) for glucose detection. This novel ML may improve patient compliance to blood glucose monitoring procedures by reducing lancing-related pain.

A ketogenic diet (KD) is known to have beneficial health effects. Various types of KD interventions have been applied to manage metabolic syndrome based on modification of diet parameters such as duration of intervention, macronutrient components, and total calories. Nevertheless, the beneficial health impact of isocaloric KD is largely unknown, especially in healthy subjects. The present study investigated the acute effects of a 3-day isocaloric KD. In this non-randomized intervention study, we recruited 15 healthy volunteers aged 24-38 years (7 men and 8 women) and placed them on an isocaloric KD restricting intake of carbohydrates but not energy (75% fat, 20% protein, 5% carbohydrate) for 3 days. Biochemical profiles and laboratory measurements were performed. Peripheral blood monocular cells were cultured, and measured cell stimulated cytokines. After short-term isocaloric KD, subjects lost body weight and serum free fatty acid levels were increased. These results accompanied elevated serum β-hydroxybutyrate (BHB) concentration and fibroblast growth factor 21 (FGF21) levels and improved insulin sensitivity. Regarding the direct effect of BHB on inflammasome activation, interleukin-1β (IL-1β) and tumor necrosis factor-α secretion in response to adenosine triphosphate or palmitate stimulation in human macrophages decreased significantly after isocaloric KD. Inclinicaltrials.gov (NCT02964572).

Aims Obesity is the most common risk factor for type 2 diabetes. However, not all obese individuals develop diabetes. In the era of precision medicine, metabolomics may reveal the fundamental metabolic status of an individual. Our aim was to assess the association of metabolites with incident type 2 diabetes in obese individuals using Korean Genome and Epidemiology Cohort Study. Methods Using 12 years of metabolomic data from 2,580 individuals, we performed a metabolomic study to define metabolically healthy obesity in an obese population (n = 704) with incident type 2 diabetes. Cox proportional hazards regression model and survival analysis were performed adjusted for the traditional risk factors of type 2 diabetes. Results Our study revealed that spermine, acyl-alkyl phosphatidylcholines (C34:3, C36:3, C42:1), hydroxy sphingomyelin (C22:2, C14:1), and sphingomyelin (C16:0) were associated with incident type 2 diabetes in obese individuals after the adjustment for risk factors and correction of multiple comparisons by Bonferroni method. Five metabolites (except hydroxy sphingomyelin C14:1 and sphingomyelin C16:0) were also significantly associated with incident type 2 diabetes in lean individuals. Conclusions This study highlights the need for defining metabolically healthy obesity based on serum metabolites and elucidates potential biomarkers for type 2 diabetes in an obese population.

Background In Korea, the Korean Laboratory Accreditation Program (KLAP) has set minimum standards for verification of clinical test performance. This verification process is time-consuming and labor-intensive when performed manually. We developed a free, statistical software program for KLAP, using the R language (R Foundation for Statistical Computing, Vienna, Austria). Methods We used CLSI guidelines for the algorithm. We built graphic user interfaces, including data input, with Embarcadero Delphi EX4 (Embarcadero Technologies, Inc., Texas, USA). The R Base Package and MCR Package for Method Comparison Regression were used to implement statistical and graphical procedures. Results Our program LaboStats has six modules: parallel test, linearity, method comparison, precision, reference interval, and cutoff. Data can be entered into the field either manually or by copying and pasting from an MS Excel worksheet. Users can print out precise reports. Conclusions LaboStats can be useful for evaluating clinical test performance characteristics and preparing documents requested by KLAP.

In this work, medical diagnosis of sepsis was conducted via quantitative analysis of lysophosphatidylcholine 16:0 (LPC 16:0) by using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry based on a parylene-matrix chip. In the first step, specific mass peaks for the diagnosis of sepsis were searched by comparing MALDI-TOF mass spectra of sepsis patient sera with healthy controls and pneumonia patient sera. Two mass peaks at m/z = 496.3 and 518.3 were chosen as those that are specifically different for sepsis sera to compare with healthy controls and pneumonia patient sera. These mass peaks were identified to be protonated and sodium adducts of LPC 16:0 by using tandem mass spectra (MS2 and MS3) of purely synthesized LPC 16:0 and extracted LPC 16:0 from a healthy control and a sepsis patient. In the next step, a standard curve for LPC 16:0 for the quantitative analysis of LPC 16:0 with MALDI-TOF MS based on the parylene-matrix chip was prepared, and the statistical correlation to the LC-MS analysis results was demonstrated by using the Bland-Altman test and Passing-Bablok regression. Finally, MALDI-TOF MS based on the parylene-matrix chip was used for the quantification of LPC 16:0 with sera from patients with severe sepsis and septic shock (n = 143), pneumonia patients (n = 12), and healthy sera (n = 31). The sensitivity and the selectivity of medical diagnosis of sepsis was estimated to be 97.9% and 95.5% by using MALDI-TOF MS based on the parylene-matrix chip, respectively.

Background The use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) has substantially increased in clinical laboratories worldwide. To assess the status of clinical LC-MS/MS testing in Korean laboratories, a questionnaire survey was performed by the Clinical Mass Spectrometry Research Committee of the Korean Society of Clinical Chemistry. Methods The questionnaire was distributed to 19 clinical laboratories performing clinical LC-MS/MS from April to May 2018. It asked about general characteristics of the laboratory and commonly utilized clinical LC-MS/MS tests: newborn screening, tacrolimus test, vitamin D test, and plasma metanephrine test. Frequency analysis and other statistical analyses were performed. Results A total of 17 laboratories responded. The median number of LC-MS/MS instruments, laboratory medicine physicians, and technicians in each laboratory was three, one, and two, respectively. Nine laboratory directors had >10 years of experience with clinical LC-MS/MS. For each LC-MS/MS test, at least two concentrations of QC materials were measured every 24 hours during clinical testing, and all laboratories used QC acceptability criteria based on their established QC means and SDs. All laboratories participated in an external quality assessment program. However, there was inter-laboratory variability in sample preparation methods, instruments, reagents, internal standards, and calibrators. Conclusions LC-MS/MS has been successfully introduced in Korean clinical laboratories and is used within a quality framework. Further efforts for harmonization on a nationwide basis could facilitate the widespread use of LC-MS/MS.

Phenytoin has been decreasingly used because of the high interindividual variability in drug concentration and the narrow therapeutic window. Despite such drawbacks, phenytoin is still essential as a second-line therapy for status epilepticus when patients are resistant to benzodiazepines. This study aimed to develop a population pharmacokinetic model of phenytoin and to propose the optimal dose regimen of phenytoin in Korean epilepsy patients. Concentrations collected from electronic medical records for 117 patients, with 1 or 2 measurements per patient, were analyzed using NONMEM 7.3.0. One-compartment model with first-order elimination where allometry scaling was considered best described the data, yielding the estimates of V and CL of 68.19 (L) and 0.63 (L/h), respectively, for patients with a body weight of 60 kg. Covariate analyses showed that, after birth, clearance increases with age, reaching adult level at 4 years, and after 20 years, it decreases with age. Simulation results showed that the dosing interval should be reduced to achieve optimal dosing in neonates and infants, and the optimal dose required increases with weight. This work demonstrates that a model-based approach can serve as a useful tool to individualize phenytoin therapy.

Background While the introduction of automated urine analyzers is expected to reduce the labor involved, turnaround time and potential assay variations, microscopic examination remains the “gold standard” for the analysis of urine sediments. In this study, we evaluated the analytical and diagnostic performance of five recently introduced automated urine sediment analyzers. Methods A total of 1016 samples were examined using five automated urine sediment analyzers and manual microscopy. Concordance of results from each automated analyzer and manual microscopy were evaluated. In addition, image and microscopic review rates of each system were investigated. Results The proportional bias for red blood cells (RBCs), white blood cells (WBCs) and squamous epithelial cells in the automated urine sediment analyzers were within ±20% of values obtained using the manual microscope, except in the cases of RBCs and WBCs analyzed using URiSCAN PlusScope and Iris iQ200SPRINT, respectively. The sensitivities of Roche Cobas® u 701 and Siemens UAS800 for pathologic casts (73.6% and 81.1%, respectively) and crystals (62.2% and 49.5%, respectively) were high, along with high image review rates (24.6% and 25.2%, respectively). The detection rates for crystals, casts and review rates can be changed for the Sysmex UF-5000 platform according to cut-off thresholds. Conclusions Each automated urine sediment analyzer has certain distinct features, in addition to the common advantages of reducing the burden of manual processing. Therefore, laboratory physicians are encouraged to understand these features, and to utilize each system in appropriate ways, considering clinical algorithms and laboratory workflow.

Background Bile acids (BAs) have been demonstrated to exert a variety of metabolic effects and alterations in BAs have been reported in patients with obesity, insulin resistance (IR) and type 2 diabetes mellitus (T2DM). However, it is unclear which metabolic condition is the main contributor to alterations in BAs. In this study, we investigate the associations between different BA profiles with glycemia, obesity or IR status. Methods Fasting serum concentrations of 15 BA species were determined in a total of 241 individuals (71 drug-naïve patients with T2DM, 95 patients with impaired fasting glucose [IFG], and 75 healthy controls. Results A comparison of the mean values of the BAs revealed no significant differences between normoglycemic controls and patients with IFG or T2DM. However, when the entire cohort was divided according to the presence of IR as determined by a homeostasis model assessment of insulin resistance (HOMA-IR) value >2.5, the levels of total BA and most species of BAs were significantly higher in patients with IR than in patients without. In the correlation analysis, most species of BAs, as well as total BA, were significantly associated with HOMA-IR levels. Furthermore, when the subjects were divided into four groups according to IR and diabetic status, subjects with IR had significantly higher total BAs than participants without IR both in diabetic and non-diabetic groups. Ultimately, multiple linear regression analysis identified HOMA-IR as the only significant contributor to most serum BA species. Conclusions Our findings support the essential role of IR in regulating BA metabolism and that this effect is independent of diabetic status.

Context In the management of growth hormone (GH)–secreting pituitary adenomas, the oral glucose tolerance test (OGTT) has been the gold standard not only for diagnoses but also for the determination of biochemical remission. Insulin-like growth factor-1 (IGF-1) is an essential biomarker, although it should be adjusted for both age and sex. Objective We evaluated whether IGF-1 levels could serve as a reliable alternative to an OGTT for disease monitoring after the surgical treatment of acromegaly. We retrospectively reviewed the medical records of 320 patients who underwent surgical resection of their GH-secreting pituitary tumors at the Severance hospital. Receiver operator characteristic (ROC) analyses were performed to validate the accuracy of IGF-1 levels for the assessment of remission. In addition, regression analyses were performed to identify factors associated with discrepancy between OGTT and IGF-1 levels. Results Except for 1 week after surgery, ROC analyses showed an area under the curve of greater than 0.8 for IGF-1 at all time points. Of 320 patients, 270 achieved endocrine remission after surgery alone. Among these patients, IGF-1 levels were normalized in 250 patients. The mean duration from surgery to IGF-1 normalization was 4.7 months. Regression analyses demonstrated that risk of failed IGF-1 normalization was increased by 3.1-fold when the tumor invaded the cavernous sinus and increased by 9.0-fold in patients with incomplete tumor removal. Conclusion IGF-1 level is a reliable alternative to OGTT and plays a valuable role in monitoring acromegaly status.

Background Sepsis is a potentially fatal condition influenced by pathogens and host factors. However, the current sepsis biomarkers, such as white blood cell count, C-reactive protein, and procalcitonin levels, show unsatisfactory performance in terms of diagnostic sensitivity and specificity in clinical practice. Thus, we developed and validated a new sepsis biomarker using amino acid profiling. Methods We used two independent groups. The training and validation groups included 161 and 22 healthy controls, 123 and 50 patients with systemic inflammatory response syndrome, and 115 and 45 patients with sepsis, respectively. We measured and analyzed the serum amino acid levels using mass spectrometry to select candidate amino acids that could differentiate sepsis from other conditions. Then, several possible multivariate indexes were developed by generating a formula with different combinations of candidate amino acids. The formula showing the best performance was selected and validated further.Results Kynurenine, tryptophan, phenylalanine, arginine, aspartic acid, glutamic acid, and glutamine were selected as candidate amino acids. Ten possible formulae were generated, and that with the highest diagnostic performance was selected. In the validation group, the area under the receiving operating characteristic curve of the selected multivariate index (0.931) was similar to that of procalcitonin (0.945). Moreover, the generated multivariate index showed potential as a prognostic marker. Conclusions Amino acid composition in patients with sepsis differs significantly from that in healthy individuals and in patients with only inflammation. The newly developed multivariate index is expected to be feasible as a sepsis biomarker in clinical practice in the near future.

Non-alcoholic fatty liver disease (NAFLD) is the major cause of chronic liver disease, yet cost-effective and non-invasive diagnostic tools to monitor the severity of the disease are lacking. We aimed to investigate the metabolomic changes in NAFLD associated with therapeutic responses. It was conducted in 63 patients with NAFLD who received either ezetimibe plus rosuvastatin or rosuvastatin monotherapy. The treatment response was determined by MRI performed at baseline and week 24. The metabolites were measured at baseline and week 12. In the combination group, a relative decrease in xanthine was associated with a good response to liver fat decrease, while a relative increase in choline was associated with a good response to liver stiffness. In the monotherapy group, the relative decreases in triglyceride (TG) 20:5_36:2, TG 18:1_38:6, acetylcarnitine (C2), fatty acid (FA) 18:2, FA 18:1, and docosahexaenoic acid were associated with a decrease in liver fat, while hexosylceramide (d18:2/16:0) and hippuric acid were associated with a decrease in liver stiffness. Models using the metabolite changes showed an AUC of >0.75 in receiver operating curve analysis for predicting an improvement in liver fat and stiffness. This approach revealed the physiological impact of drugs, suggesting the mechanism underlying the development of this disease.

Stimuli-responsive self-assembly of functional amphiphilic molecules by specific chemical stimulants is a promising strategy for sensor application. Herein, we demonstrate a fast optical detection of urea in human urine by exploiting bolaform perylene diimide functionalized with imidazoles (PDI-Hm), whose aggregation is induced by urea hydrolysis. The hydroxides produced from the enzymatic urea hydrolysis deprotonate the imidazoles to reduce electrostatic repulsion between PDI-Hm molecules in a HCl-methanol mixture, thereby leading to aggregation and consequent fluorescence quenching. The molecular interaction of PDI-Hm was further scrutinized to understand the aggregation behavior driven by the screening of electrical repulsion. As an optical sensing probe, PDI-Hm displays a prompt response (

Procalcitonin (PCT) is a useful bacterial infection biomarker with the potential for guiding antibiotic therapy. We evaluated the concordance of three automated PCT immunoassays: Kryptor (BRAHMS GmbH, Hennigsdorf, Germany), Atellica IM 1600 (Siemens Healthcare Diagnostics, Munich, Germany), and Cobas e801 (Roche Diagnostics, Mannheim, Germany). In 119 serum samples with a PCT concentration

The adoptive transfer of ex vivo-expanded natural killer (NK) cells has recently been employed as an alternative cancer treatment in certain institutions. However, the safety profiles of this strategy remain uncharacterized. We evaluated three patients who exhibited elevated serum parathyroid hormone (PTH) levels without the relevant clinical manifestations and had a history of autologous NK cell therapy. The serum PTH concentration was measured using a second-generation PTH assay, and the serum thyroglobulin concentration was measured using a second-generation thyroglobulin assay. Subsequently, the PTH or thyroglobulin concentration obtained using heterophile-blocking tube (HBT) for a secondary confirmation assay was measured and compared with the result of the initial assay. The three patients had falsely elevated serum PTH and thyroglobulin levels owing to heterophile antibody interference associated with NK cell therapy that persisted for at least up to 12 months after the treatment and was confirmed by normalization of hormone levels after HBT treatment. We propose that certain types of mouse monoclonal antibodies used to stimulate NK cells can induce heterophile antibodies. Abnormal laboratory test results in individuals administered NK cell therapy without the relevant clinical manifestations must be examined in the context of heterophile antibody interference to avoid misdiagnosis and unnecessary testing.

This study aimed to investigate the potential of using changes in the plasma levels of trimethylamine N-oxide (TMAO), a gut microbiota-derived metabolite, as a biomarker in early Parkinson's disease (PD).Plasma TMAO levels were measured in 85 patients with drug-naïve early stage PD and 20 healthy controls. A linear mixed model was used to assess longitudinal changes in levodopa-equivalent dose (LED) during follow-up (2 y) in three tertile PD groups according to plasma TMAO levels. Additionally, a Cox regression analysis was performed to assess the effect of plasma TMAO levels on dementia conversion.Plasma TMAO levels of patients with PD were lower than those of healthy controls. A linear mixed model demonstrated that patients with PD and lower levels of TMAO (4.75 μmol/L; i.e., lowest tertile group) exhibited faster increases in LED over time. The Cox regression model did not reveal that plasma TMAO level was associated with the risk for dementia conversion (P = 0.488). However, when we divided patients with PD into two subgroups according to bet cutoff TMAO level to maximize the log-rank statistics, the PD group with a low plasma TMAO level (6.92 μmol/L) had a higher risk (with borderline statistical significance) for PD-dementia conversion than the group with a high TMAO level (hazard ratio: 7.565; 95% confidence interval, 1.004-57.019; P = 0.050).The results demonstrate that lower baseline plasma TMAO levels are associated with faster increases in LED and tend to increase the risk for PD-dementia conversion, suggesting the prognostic implications of TMAO in early stage PD.

In this work phospholipid quantification was carried out using an enzymatic assay based on cyclic voltammetry of the condensation product of N-ethyl-N-(2-hydroxy-3-sulfopropyl)-3,5-dimethoxyaniline sodium salt (DAOS) and 4-aminoantipyrine (4-AP) with a graphite electrode. For the optimization of electrochemical measurement for the product, electrochemical properties such as the electrochemical window, double layer capacitance (Cdl) and electron transfer rate (kapp) were analyzed for a graphite-electrode and Au-electrode. The phospholipid enzymatic assay based the on electrochemical measurement using the graphite electrode was applied to the diagnosis of sepsis for sera from healthy volunteers (n = 16), patients with systemic inflammatory response syndrome (SIRS, n = 16) and severe sepsis patients (n = 24). Finally, the phospholipid quantification results from the electrochemical measurement were statistically compared with the conventional method based on optical density measurement.

Background The Alinity i system (Abbott), a recently developed automated immunoassay analyzer, has a compact footprint and a throughput of 200 tests per hour. Here, we present the first performance evaluation of thyroid function test (TFT) on the Alinity i system. Methods We performed precision, linearity, comparison, functional sensitivity, carryover, and reference interval verification of 4 hormones (Thyroid Stimulation Hormone; TSH, total T3, free T4, and total T4) using the reagents provided by the manufacturer following the guidelines of the Clinical Laboratory Standards Institute. The performance of Alinity i was compared to that of the Architect i2000 immunoassay analyzer (Abbott, US). Results The within-laboratory coefficients of variation for all the hormones were 1.6–3.6%. Linearity was observed for all the hormones over the entire tested analytical range (R2 ≥ 0.99). The results for all the evaluated hormones using Alinity i system strongly correlated (r ≥ 0.978) with those from Architect i2000. Functional sensitivity was lower than the lower limit of the analytical measurement range. Sample carryover was less than 1.0%. Conclusions TFTs on the Alinity i system showed acceptable performance in terms of precision, linearity, comparison, functional sensitivity, and carryover. Therefore, this system could be a useful laboratory tool for performing TFTs.

배경:소변 검체 배양 후 신속하게 항균제 감수성 결과를 얻는 것은 적절한 항균제로 환자를 치료하기 위하여 중요하다. 본 연구에서는 EUCAST가 제시한 혈액 신속 직접 항균제 감수성 검사법을 뇨 검체에서 적용하여 평가하고자 하였다.방법: 유세포 분석기(Sysmex UF-1000i, Japan)와 그람염색법으로 선별검사 후, 2 × 104 bacteria/ mL 이상의 단일 세균 형태를 갖는 103개의 뇨 검체를 대상으로 하였다. EUCAST 혈액 신속 직접 항균제 감수성 검사법과 동일하게, Mueller-Hinton 우무 배지에 뇨 검체를 직접 접종한 후, 항균제 디스크를 부착하였다. 이를 4, 6, 8 시간 후에 항균제 디스크 주변 균증식 억제대 지름을 육안과 디지털 스캐너(BIOMIC vision analyzer, Giles scientific, USA)로 측정하였다. 항균제 감수성 검사의 해석은 기존 VITEK 2 시스템과 비교하였으며, 결과가 불일치한 경우 E-test법으로 확인하였다결과:Ampicillin, cefazolin, aztreonam, ceftazidime, cefotaxime, cefoxitin, cefepime, gentamycin, ciprofloxacin, cotrimoxazole에서는 신속 직접 항균제 감수성 검사법과 기존의 항균제 감수성 검사법 간의 weighted kappa value가 0.75 이상으로 우수한 상관관계를 보였다. 1,545개 균주-항균제 감수성 시험 결과에서, 신속 직접 항균제 감수성 검사법의 categorical agreement는 1,442 (93.3%), minor errors는 76 (4.9%), major error는 9 (0.6%) , very major errors는 18 (1.2%)으로 신뢰성이 있었다.결론: 신속 직접 항균제 감수성 검사법으로 Enterobacteriaceae를 포함한 뇨 검체에서 8시간 내에 신뢰할 수 있는 항균제 감수성 검사 결과를 얻을 수 있었다. 신속 직접 항균제 감수성 검사법은 요로감염에서 임상의가 적절한 항균제 치료를 시작하는데 유용할 것으로 판단하였다.

We investigated the potential application of preoperative serum metabolomes in predicting recurrence in patients with resected pancreatic cancer. From November 2012 to June 2014, patients who underwent potentially curative pancreatectomy for pancreatic ductal adenocarcinoma were examined. Among 57 patients, 32 were men; 42 had pancreatic head cancers. The 57 patients could be clearly categorized into two main clusters using 178 preoperative serum metabolomes. Patients within cluster 2 showed earlier tumor recurrence, compared with those within cluster 1 (p = 0.034). A nomogram was developed for predicting the probability of early disease-free survival in patients with resected pancreatic cancer. Preoperative cancer antigen (CA) 19–9 levels and serum metabolomes PC.aa.C38_4, PC.ae.C42_5, and PC.ae.C38_6 were the most powerful preoperative clinical variables with which to predict 6-month and 1-year cancer recurrence-free survival after radical pancreatectomy, with a Harrell’s concordance index of 0.823 (95% CI: 0.750–0.891) and integrated area under the curve of 0.816 (95% CI: 0.736–0.893). Patients with resected pancreatic cancer could be categorized according to their different metabolomes to predict early cancer recurrence. Preoperative detectable parameters, serum CA 19–9, PC.aa.C38_4, PC.ae.C42_5, and PC.ae.C38_6 were the most powerful predictors of early recurrence of pancreatic cancer.

Aims We evaluated specific alterations in amino acids (AAs) profile in patients with type 2 diabetes mellitus (T2DM) and impaired fasting glucose (IFG) compared with healthy controls. In addition, we tried to find the mechanisms behind these AA alterations. Methods Twenty AAs, TNF-α, and IL-6 were analyzed in fasting serum samples from a total of 198 individuals (56 drug-naive patients with T2DM, 69 patients IFG, and 73 healthy controls). The C2C12 mouse myoblast cell lines were used to examine the changes of MAFbx and MuRF1 expressions, which are muscle specific E3 ligases acting as major mediators of skeletal muscle proteolysis, after development of insulin resistance induced by palmitate treatment. Results In addition to branched chain amino acids BCAAs, fasting serum AAs such as glutamic acid, lysine, phenylalanine, arginine, alanine, tyrosine, aspartic acid, were higher in patients with T2DM and intermediately elevated in patients with IFG compared with normoglycemic controls. These serum AA concentrations positively correlated with fasting glucose, homeostasis model assessment of insulin resistance (HOMA-IR), and pro-inflammatory cytokines. In addition, HOMA-IR and pro-inflammatory cytokines were two important independent predictors of serum AA levels. In vitro experiments showed that palmitate treatment in C2C12 myotubes induced insulin resistance, increased pro-inflammatory cytokine gene expression, and increased MAFbx gene and protein expression. Conclusions The increase in fasting serum AAs can be an early manifestation of insulin resistance. Increased muscle proteolysis induced by insulin resistance and inflammatory cytokines can be a possible mechanism for the rise in serum AA levels.