A novel LC-MS/MS assay for low concentrations of creatinine in sweat and saliva to validate biosensors for continuous monitoring of renal function.

Monitoring of kidney function traditionally relies on plasma creatinine concentrations, necessitating invasive blood draws. Non-invasively obtainable biofluids, such as sweat and saliva, present a patient-friendly alternative with potential for continuous monitoring. This study focusses on developing and validating a novel Liquid Chromatography- tandem Mass Spectrometry (LC-MS/MS) assay as a reference test for measuring low creatinine concentrations in sweat and saliva.

Immunoaffinity Intact Top-Down Mass Spectrometry for Quantification of Neuron-Specific Enolase Gamma, a Low-Abundance Protein Biomarker.

Quantification of intact proteins in serum by liquid chromatography high-resolution mass spectrometry (HRMS) may be a useful alternative to bottom-up LC-MS or conventional ligand binding assays, due to reduced assay complexity and by providing additional information, such as isoform differentiation or detection of post-translational modifications. The 47.2 kDa lung cancer tumor marker neuron-specific enolase γ (NSEγ) was quantified in a clinically relevant concentration range of 6.

Partial protein binding of uracil and thymine affects accurate dihydropyrimidine dehydrogenase (DPD) phenotyping.

Fluorouracil is among the most used antimetabolite drugs for the chemotherapeutic treatment of various types of gastrointestinal malignancies. Dihydropyrimidine dehydrogenase (DPYD) genotyping prior to fluorouracil treatment is considered standard practice in most European countries. Yet, current pre-therapeutic DPYD genotyping procedures do not identify all dihydropyrimidine dehydrogenase (DPD)-deficient patients.

Immunoaffinity Intact-Mass Spectrometry for the Detection of Endogenous Concentrations of the Acetylated Protein Tumor Biomarker Neuron Specific Enolase.

Intact-mass spectrometry has huge potential for clinical application, as it enables both quantitative and qualitative analysis of intact proteins and possibly unlocks additional pathophysiological information via, e.g., detection of specific post-translational modifications (PTMs).

Transfusion of ever-pregnant donor red blood cells and mortality of male patients.

Previous studies found exposure to red blood cell transfusions from female donors who have been pregnant reduces survival in male patients compared to exposure to male donor products, but evidence is not consistent. We postulate the previously observed association is modified by offspring sex, with an expected increased mortality risk for male patients receiving units from female donors with sons. Here, marginal structural models were used to assess the association between exposure to units from ever-pregnant donors, ever-pregnant donors with sons and ever-pregnant donors with daughters, and mortality.

Strengths and challenges in current lung cancer care: Timeliness and diagnostic procedures in six Dutch hospitals.

Objectives: Timely diagnosis of lung cancer (LC) is crucial to achieve optimal patient care and outcome. Moreover, the number of procedures required to obtain a definitive diagnosis can have a large influence on the life expectancy of a patient. Here, adherence with existing Dutch guidelines for timeliness and type and number of invasive and imaging procedures was assessed.

The correlation of urea and creatinine concentrations in sweat and saliva with plasma during hemodialysis: an observational cohort study.

Objectives: Urea and creatinine concentrations in plasma are used to guide hemodialysis (HD) in patients with end-stage renal disease (ESRD). To support individualized HD treatment in a home situation, there is a clinical need for a non-invasive and continuous alternative to plasma for biomarker monitoring during and between cycles of HD. In this observational study, we therefore established the correlation of urea and creatinine concentrations between sweat, saliva and plasma in a cohort of ESRD patients on HD.

Effect of conventional hemodialysis on the apixaban plasma concentration.

Purpose: Apixaban is a factor Xa inhibitor used in patients undergoing hemodialysis treatment. The objective of this study is to investigate the effect of hemodialysis on apixaban plasma concentrations.

Methods: This observational study is on patients treated with apixaban 2.

Donor pregnancies and transfusion recipient mortality: A role for red blood cell storage?

Background And Objectives: Donor characteristics have been implicated in transfusion-related adverse events. Uncertainty remains about whether sex, and specifically pregnancy history of the blood donor, could affect patient outcomes. Whether storage duration of the blood product could be important for patient outcomes has also been investigated, and a small detrimental effect of fresh products remains a possibility.

Quantification of the lung cancer tumor marker CYFRA 21-1 using protein precipitation, immunoaffinity bottom-up LC-MS/MS.

Objectives: Numerous studies have proven the potential of cytokeratin 19 fragment 21-1 (CYFRA 21-1) detection in the (early) diagnosis and treatment monitoring of non-small cell lung cancer (NSCLC). Conventional immunoassays for CYFRA 21-1 quantification are however prone to interferences and lack diagnostic sensitivity and standardization. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an emerging approach based on a different, often superior, detection principle, which may improve the clinical applicability of CYFRA 21-1 in cancer diagnostics.

Analysis of Neuron-Specific enolase isozymes in human serum using immunoaffinity purification and liquid chromatography-tandem mass spectrometry quantification.

Neuron-specific enolase (NSE) is a promising small-cell lung cancer (SCLC) biomarker composed of αγ and γγ isozyme dimers. As the conventional immunoassays are prone to interferences and cannot differentiate between the isozymes, we developed a multiplex immunoaffinity (IA) liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the quantification of NSEα and NSEγ in human serum. A calibrator was prepared by performing cold denaturation of recombinantly expressed αα and γγ enolase dimers to induce a new dimer equilibrium that was determined to be approximately 1αγ:1γγ:1αα.

Heterophilic antibodies leading to falsely positive D-dimer concentration in an adolescent.

Background: We present the case of a 15-year-old adolescent with suspected pulmonary embolism and repeatedly elevated D-dimer levels.

Key Clinical Question: We aim to determine the cause for elevated D-dimer levels in a patient without venous thromboembolism.

Clinical Approach: When the D-dimer measurement was repeated with different assays, D-dimer levels were within the normal reference interval.

Liquid biopsy-based decision support algorithms for diagnosis and subtyping of lung cancer.

Objectives: Pathologic subtyping of tissue biopsies is the gold standard for the diagnosis of lung cancer (LC), which could be complicated in cases of e.g. inconclusive tissue biopsies or unreachable tumors.

Quantification of uracil, dihydrouracil, thymine and dihydrothymine for reliable dihydropyrimidine dehydrogenase (DPD) phenotyping critically depend on blood and plasma storage conditions.

Establishing dihydropyrimidine dehydrogenase (DPD) activity is highly important in determining the correct starting dose of fluoropyrimidines such as 5-fluorouracil and capecitabine. The concentration ratio of endogenous uracil with its metabolite dihydrouracil (DHU) is a well-known parameter that is linked to DPD activity. Concentration ratios such as thymine over its DPD-converted metabolite dihydrothymine (DHT) is less described and may serve as an alternative diagnostic biomarker for DPD activity.

The effect of extended c, E and K matching in females under 45 years of age on the incidence of transfusion-induced red blood cell alloimmunisation.

Maternal alloantibodies directed against fetal red blood cell (RBC) antigens may cause potentially life-threatening haemolytic disease of the fetus and newborn (HDFN). Dutch transfusion guidelines therefore prescribe preventive cEK matching for all (pre-)fertile females. To quantify the impact of cEK matching, we compared overall and antigen-specific cumulative RBC alloimmunisation incidences in females and males aged <45 years.

Novel urinary biomarkers ADXBLADDER and bladder EpiCheck for diagnostics of bladder cancer: A review.

Non-muscle-invasive bladder cancer (NMIBC) is accompanied with high incidence and recurrence rates. The extensive need for cystoscopic follow up causes substantial patient discomfort and leads to a high economic burden. Cytology of exfoliated tumor cells in urine is not able to safely reduce or replace the amount of cystoscopies.

Association between renal failure and red blood cell alloimmunization among newly transfused patients.

Background: Renal failure and renal replacement therapy (RRT) affect the immune system and could therefore modulate red blood cell (RBC) alloimmunization after transfusion.

Study Design And Methods: We performed a nationwide multicenter case-control study within a source population of newly transfused patients between 2005 and 2015. Using conditional multivariate logistic regression, we compared first-time transfusion-induced RBC alloantibody formers (N = 505) with two nonalloimmunized recipients with similar transfusion burden (N = 1010).

Optimizing hepcidin measurement with a proficiency test framework and standardization improvement.

Objectives: Hepcidin measurement advances insights in pathophysiology, diagnosis, and treatment of iron disorders, but requires analytically sound and standardized measurement procedures (MPs). Recent development of a two-level secondary reference material (sRM) for hepcidin assays allows worldwide standardization. However, no proficiency testing (PT) schemes to ensure external quality assurance (EQA) exist and the absence of a high calibrator in the sRM set precludes optimal standardization.

Dabigatran trough concentrations in very elderly patients.

Objectives: The aim of this observational study was to explore dabigatran concentrations in elderly and very elderly patients in a real-life population. Patients aged >75 years receiving dabigatran have a significantly higher risk of gastrointestinal bleeding compared withthose receiving warfarin. High trough concentrations have an important impact on this bleeding risk.

Correction of the NSE concentration in hemolyzed serum samples improves its diagnostic accuracy in small-cell lung cancer.

Neuron-specific enolase (NSE) is a well-known biomarker for the diagnosis, prognosis and treatment monitoring of small-cell lung cancer (SCLC). Nevertheless, its clinical applicability is limited since serum NSE levels are influenced by hemolysis, leading to falsely elevated results. Therefore, this study aimed to develop a hemolysis correction equation and evaluate its role in SCLC diagnostics.

Adherence to dabigatran etexilate in atrial fibrillation patients intended to undergo electrical cardioversion.

Aims: Effective anticoagulation in patients undergoing electrical cardioversion (ECV) for symptomatic atrial fibrillation is important to prevent adverse events. High medication adherence is a requirement. In patients with newly diagnosed atrial fibrillation (n = 169) who were intended to undergo ECV, the aim of this study was to measure self-reported short- and long-term adherence, evaluate whether dabigatran plasma concentrations reflect adherence, measure treatment satisfaction and assess whether adherence and treatment satisfaction are correlated.

Optimizing charge state distribution is a prerequisite for accurate protein biomarker quantification with LC-MS/MS, as illustrated by hepcidin measurement.

Background: Targeted quantification of protein biomarkers with liquid chromatography-tandem mass spectrometry (LC-MS/MS) has great potential, but is still in its infancy. Therefore, we elucidated the influence of charge state distribution and matrix effects on accurate quantification, illustrated by the peptide hormone hepcidin.

Methods: An LC-MS/MS assay for hepcidin, developed based on existing literature, was improved by using 5 mM ammonium formate buffer as mobile phase A and as an elution solution for solid phase extraction (SPE) to optimize the charge state distribution.

Comprehensive characteristics of the anticoagulant activity of dabigatran in relation to its plasma concentration.

Background: Issues with laboratory measurement of dabigatran include: 1. Do coagulation assays reflect dabigatran plasma concentrations? 2. Do samples from patients treated with dabigatran have the same coagulability as dabigatran-spiked samples from healthy volunteers? 3.