Angela W.S. Fung

Bio: Angela W.S. Fung is an academic researcher from University of British Columbia. The author has contributed to research in topics: Point-of-care testing & Medicine. The author has an hindex of 8, co-authored 18 publications receiving 105 citations. Previous affiliations of Angela W.S. Fung include University of Alberta & Ottawa Hospital.

Emerging role of clinical mass spectrometry in pathology.

Abstract: Mass spectrometry-based assays have been increasingly implemented in various disciplines in clinical diagnostic laboratories for their combined advantages in multiplexing capacity and high analytical specificity and sensitivity. It is now routinely used in areas including reference methods development, therapeutic drug monitoring, toxicology, endocrinology, paediatrics, immunology and microbiology to identify and quantify biomolecules in a variety of biological specimens. As new ionisation methods, instrumentation and techniques are continuously being improved and developed, novel mass spectrometry-based clinical applications will emerge for areas such as proteomics, metabolomics, haematology and anatomical pathology. This review will summarise the general principles of mass spectrometry and specifically highlight current and future clinical applications in anatomical pathology.

Pediatric reference intervals for 29 Ortho VITROS 5600 immunoassays using the CALIPER cohort of healthy children and adolescents

Abstract: Background Accurate reference intervals (RIs) based on a healthy pediatric population are essential for pediatric test result interpretation. The CALIPER project has recruited a large healthy cohort and completed a series of a priori studies to address gaps in pediatric RIs. As immunoassays from different manufacturers for endocrine and special chemistry markers are not standardized and show marked intermethod differences, direct RI studies are needed for each major analytical platform. Here, we report age- and sex-specific pediatric RIs for 29 immunoassays on the Ortho Clinical Diagnostics (Ortho) VITROS® 5600 analyzer. Methods Health information and blood samples were collected from healthy pediatric subjects. Using the Ortho VITROS 5600 Integrated System MicroWell Technology, 29 biomarkers were measured. Analyte concentrations were partitioned by age and sex according to the Harris and Boyd method. After removing outliers, age- and sex-specific RIs and corresponding 90% confidence intervals were calculated according to CLSI guidelines. Results All analytes required age partitioning except β-human chorionic gonadotropin (β-hCG), cancer antigen 15-3 (CA15-3), rubella immunoglobulin G (rubella IgG), and vitamin D. Several analytes including estradiol, progesterone, testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), free triiodothyronine (FT3), total triiodothyronine (TT3), total thyroxine (TT4), thyroid uptake, ferritin, intact parathyroid hormone (iPTH), total prostate-specific antigen (tPSA), free prostate-specific antigen (fPSA), cancer antigen 125 (CA125), creatine kinase MB (CK-MB), and myoglobin showed sex differences, observed mostly with the onset of puberty. Conclusions Complex reference value trends were observed across the pediatric age range for several biomarkers examined on Ortho VITROS immunoassays. The availability of VITROS immunoassay RIs will enable accurate laboratory test interpretation and diagnosis for the pediatric population. As recommended by the CLSI EP28-A3c guidelines, implementation of these RIs should be validated for each laboratory's local pediatric population.

Pediatric reference intervals for 1,25-dihydroxyvitamin D using the DiaSorin LIAISON XL assay in the healthy CALIPER cohort

Abstract: BACKGROUND 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active vitamin D metabolite, plays a critical role in calcium and phosphate homeostasis 1,25(OH)2D is measured to assess calcium and phosphate metabolism, particularly during periods of profound growth and development Despite its importance, no reliable pediatric reference interval exists, with those available developed using adult populations or out-dated methodologies Using the fully automated chemiluminescence immunoassay by DiaSorin, we established 1,25(OH)2D pediatric reference intervals using healthy children and adolescents from the CALIPER cohort METHODS Serum samples from healthy subjects (0 to <19 years) were analyzed for 1,25(OH)2D using the DiaSorin LIAISON XL assay and age-specific reference intervals were established The Mann-Whitney U-test was used to determine seasonal differences Pooled neonatal and infantile samples were quantified using liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine if elevated concentrations during the first year of life may be attributed to cross-reacting moieties RESULTS Three reference interval age partitions were required with highest levels in subjects 0 to <1 year (77-471 pmol/L), which declined and narrowed after 1 year (113-363 pmol/L) and plateaued at 3 years (108-246 pmol/L) 1,25(OH)2D concentration was not significantly affected by seasonal variation or sex Elevated 1,25(OH)2D concentrations in neonatal and infantile samples may be the result of an interfering substance The absence of 3-epi-1,25-dihydroxyvitamin D in the pooled samples makes it unlikely to be the interfering moiety CONCLUSIONS Pediatric reference intervals for 1,25(OH)2D were established to improve test result interpretation in children and adolescents 1,25(OH)2D is elevated in a proportion of neonates and infants, which may be the result of a cross-reacting moiety

Evaluation of electrochemiluminescence immunoassays for immunosuppressive drugs on the Roche cobas e411 analyzer.

Abstract: Background: Therapeutic drug monitoring of immunosuppressant drugs are used to monitor drug efficacy and toxicity and to prevent organ transplant rejection. This study evaluates the analytical performance of semi-automated electrochemiluminescence immunoassays (ECLIA) for cyclosporine (CSA), tacrolimus (TAC) and sirolimus (SRL) on the Roche cobas e 411 analyzer at a major transplant hospital to assess method suitability and limitations. Methods: Residual whole blood samples from patients undergoing immunosuppressant therapy were used for evaluation. Imprecision, linearity, functional sensitivity, method comparisons and lot-to-lot comparisons were assessed. Results: Total imprecision ranged from 3.3 to 7.1% for CSA, 3.9 to 9.4% for TAC, and 4.6 to 8.2% for SRL. Linearity was verified from 30.0 to 960.9 μg/L for CSA, from 1.1 to 27.1 μg/L for TAC, and from 0.5 to 32.3 µg/L for SRL. The functional sensitivity met the manufacturer's claims and was determined to be <6.5 μg/L for CSA, 1.1 μg/L for TAC, and <0.1 µg/L for SRL (CV≤20%). Deming regression analysis of method comparisons with the ARCHITECT immunoassay yielded slopes of 0.917 (95%CI: 0.885-0.949) and r of 0.985 for CSA, 0.938 (95%CI: 0.895-0.981) and r of 0.974 for TAC, and 0.842 (0.810-1.110) and r of 0.982 for SRL. Deming regression analysis of comparisons with the LC-MS/MS method yielded slopes of 1.331 (95%CI: 1.167-1.496) and r of 0.969 for CSA, 0.924 (95%CI: 0.843-1.005) and r of 0.984 for TAC, and 0.971 (95%CI: 0.913-1.030) and r of 0.993 for SRL. Conclusions: The cobas e 411 ECLIA for CSA, TAC, and SRL have acceptable precision, linearity, and functional sensitivity. The method comparisons correlated well with the ARCHITECT immunoassay and LC-MS/MS and is fit for therapeutic drug monitoring.

The Role of Procalcitonin in Diagnosis of Sepsis and Antibiotic Stewardship: Opportunities and Challenges

Abstract: Sepsis was recently redefined as “a life-threatening organ dysfunction caused by dysregulated host-response to systemic infection” based on the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). The incidence of sepsis is increasing despite global initiatives, with a mortality ranging from 30% to 50%. A timely diagnosis of sepsis is pivotal for prompt recognition and appropriate intervention. Each hour of delay in administration of antibiotics results in an increase of 7.6% mortality for septic shock, yet overdiagnosis and inappropriate use of broad-spectrum antibiotics contribute to the emergence of antibiotic resistance. Diagnosis of sepsis is a clinical challenge. Early signs of systemic inflammation such as fever, tachycardia, and leukocytosis are not specific to sepsis. Traditionally, anaerobic and aerobic blood cultures were used to detect and identify the presence of bacterial infection; however, approximately 40% of patients with sepsis are culture-negative. Other biomarkers such as C-reactive protein (CRP;11 inflammatory) and lactate (organ dysfunction) are not early indicators and lack specificity. There is increasing evidence that support the use of procalcitonin (PCT) for diagnosis of bacterial sepsis and act as a guide to discontinue antibiotic therapy. Yet, there are concerns about the efficacy, safety, and availability of PCT. We have asked 5 experts with different roles in this field to share their thoughts on the challenges of PCT-guided diagnosis and antibiotic therapy. 1. What are the challenges in sepsis diagnosis? Joshua Hayden: In clinical journals, the question is “What are the challenges in defining sepsis?” Systemic inflammatory response syndrome (SIRS) criteria have been removed from the new Sepsis-3 definition after 25 years. A clinical syndrome that is this hard to define, not surprisingly, is difficult to diagnose. It is worth noting that the only laboratory values that currently count toward the diagnosis of sepsis are lactate and those included in …

Therapeutic Drug Monitoring of Tacrolimus-Personalized Therapy : Second Consensus Report

Abstract: Ten years ago, a consensus report on the optimization of tacrolimus was published in this journal. In 2017, the Immunosuppressive Drugs Scientific Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicity (IATDMCT) decided to issue an updated consensus report considering the most relevant advances in tacrolimus pharmacokinetics (PK), pharmacogenetics (PG), pharmacodynamics, and immunologic biomarkers, with the aim to provide analytical and drug-exposure recommendations to assist TDM professionals and clinicians to individualize tacrolimus TDM and treatment. The consensus is based on in-depth literature searches regarding each topic that is addressed in this document. Thirty-seven international experts in the field of TDM of tacrolimus as well as its PG and biomarkers contributed to the drafting of sections most relevant for their expertise. Whenever applicable, the quality of evidence and the strength of recommendations were graded according to a published grading guide. After iterated editing, the final version of the complete document was approved by all authors. For each category of solid organ and stem cell transplantation, the current state of PK monitoring is discussed and the specific targets of tacrolimus trough concentrations (predose sample C0) are presented for subgroups of patients along with the grading of these recommendations. In addition, tacrolimus area under the concentration-time curve determination is proposed as the best TDM option early after transplantation, at the time of immunosuppression minimization, for special populations, and specific clinical situations. For indications other than transplantation, the potentially effective tacrolimus concentrations in systemic treatment are discussed without formal grading. The importance of consistency, calibration, proficiency testing, and the requirement for standardization and need for traceability and reference materials is highlighted. The status for alternative approaches for tacrolimus TDM is presented including dried blood spots, volumetric absorptive microsampling, and the development of intracellular measurements of tacrolimus. The association between CYP3A5 genotype and tacrolimus dose requirement is consistent (Grading A I). So far, pharmacodynamic and immunologic biomarkers have not entered routine monitoring, but determination of residual nuclear factor of activated T cells-regulated gene expression supports the identification of renal transplant recipients at risk of rejection, infections, and malignancy (B II). In addition, monitoring intracellular T-cell IFN-g production can help to identify kidney and liver transplant recipients at high risk of acute rejection (B II) and select good candidates for immunosuppression minimization (B II). Although cell-free DNA seems a promising biomarker of acute donor injury and to assess the minimally effective C0 of tacrolimus, multicenter prospective interventional studies are required to better evaluate its clinical utility in solid organ transplantation. Population PK models including CYP3A5 and CYP3A4 genotypes will be considered to guide initial tacrolimus dosing. Future studies should investigate the clinical benefit of time-to-event models to better evaluate biomarkers as predictive of personal response, the risk of rejection, and graft outcome. The Expert Committee concludes that considerable advances in the different fields of tacrolimus monitoring have been achieved during this last decade. Continued efforts should focus on the opportunities to implement in clinical routine the combination of new standardized PK approaches with PG, and valid biomarkers to further personalize tacrolimus therapy and to improve long-term outcomes for treated patients.

The Canadian laboratory initiative on pediatric reference intervals: A CALIPER white paper.

Abstract: Laboratory investigations provide physicians with objective data to aid in disease diagnosis, clinical decision making, and patient follow up. Clinical interpretation of laboratory test results relies heavily on the availability of appropriate population-based reference intervals (i.e. normative values) or decision limits developed through clinical outcome studies. Although reference intervals are fundamental to accurate laboratory test interpretation, and thus critically important to healthcare, the need for sound evidence-based reference intervals has been largely overlooked, particularly in the pediatric population. In the field of pediatric laboratory medicine, accurate age- and sex-specific reference intervals established using samples from healthy children and adolescents have not been readily available, forcing many clinical laboratories to report adult reference intervals with pediatric test results. When pediatric reference intervals are available, they have often been established with a small sample size, inpatient or outpatient samples, outdated methodologies, and/or inappropriate statistical procedures. To address these unacceptable limitations, several national and global initiatives have begun to close the critical evidence gaps in pediatric reference intervals. Notably, the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) has made significant strides towards improving pediatric healthcare in Canada and globally. The present report is a white paper summarizing CALIPER, and provides a comprehensive compendium of the data generated through this project over the past decade as a single resource for clinical laboratory specialists, clinicians, and other healthcare workers. CALIPER launched an outreach campaign in 2008 to recruit healthy community children and adolescents, and developed a robust statistical algorithm, in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines, to develop accurate age- and sex-specific pediatric reference intervals. The first CALIPER direct reference interval study was published in 2012, with age- and sex-specific reference intervals reported for 40 common biochemical markers. To date, CALIPER has collected health information and blood samples from over 9700 community children and adolescents, and has established a comprehensive database of age- and sex-specific reference intervals for over 100 biomarkers of pediatric disease. CALIPER has also performed a series of transference and verification studies to expand the applicability of the CALIPER database to five major analytical platforms, including Abbott, Beckman, Ortho, Roche, and Siemens. Through novel knowledge translation initiatives, the CALIPER Reference Interval Database has been made freely available online ( www.caliperproject.ca ) as well as on a mobile application (CALIPER Reference App), and it is used by clinical laboratories across Canada, the United States, and globally. In addition to establishing this comprehensive pediatric reference interval database, CALIPER has also performed a series of sub-studies, including examining how reference intervals are affected by pre-analytical factors (i.e. sample stability at specific storage conditions, fasting status and time of sample collection), biological variation (i.e. intraindividual and interindividual biological variation, reference change values), and ethnicity and pubertal development stage. In this white paper, extensive tables of pediatric reference intervals are provided for easy reference for clinical laboratories worldwide. All data reported have been published in over 20 peer reviewed publications and are also available through the CALIPER Reference Interval Database as well as the CALIPER Reference App for mobile devices.

Aminoacyl-tRNA-Utilizing Enzymes in Natural Product Biosynthesis

Abstract: Aminoacyl-tRNAs were long thought to be involved solely in ribosome-dependent protein synthesis and essential primary metabolism processes, such as targeted protein degradation and peptidoglycan synthesis. About 10 years ago, an aminoacyl-tRNA-dependent enzyme involved in the biosynthesis of the antibiotic valanimycin was discovered in a Streptomyces strain. Far from being an isolated case, this discovery has been followed by the description of an increasing number of aminoacyl-tRNA-dependent enzymes involved in secondary metabolism. This review describes the three groups of aminoacyl-tRNA-dependent enzymes involved in the synthesis of natural products. Each group is characterized by a particular chemical reaction, and its members are predicted to share a specific fold. The three groups are cyclodipeptide synthases involved in diketopiperazine synthesis, LanB-like dehydratases involved in the posttranslational modification of ribosomal peptides, and transferases from various biosynthesis pathways.

Formyl-methionine as a degradation signal at the N-termini of bacterial proteins.

Abstract: In bacteria, all nascent proteins bear the pretranslationally formed N-terminal formyl-methionine (fMet) residue. The fMet residue is cotranslationally deformylated by a ribosome-associated deformylase. The formylation of N-terminal Met in bacterial proteins is not strictly essential for either translation or cell viability. Moreover, protein synthesis by the cytosolic ribosomes of eukaryotes does not involve the formylation of N-terminal Met. What, then, is the main biological function of this metabolically costly, transient, and not strictly essential modification of N-terminal Met, and why has Met formylation not been eliminated during bacterial evolution? One possibility is that the similarity of the formyl and acetyl groups, their identical locations in N-terminally formylated (Nt-formylated) and Nt-acetylated proteins, and the recently discovered proteolytic function of Nt-acetylation in eukaryotes might also signify a proteolytic role of Nt-formylation in bacteria. We addressed this hypothesis about fMet-based degradation signals, termed fMet/N-degrons, using specific E. coli mutants, pulse-chase degradation assays, and protein reporters whose deformylation was altered, through site-directed mutagenesis, to be either rapid or relatively slow. Our findings strongly suggest that the formylated N-terminal fMet can act as a degradation signal, largely a cotranslational one. One likely function of fMet/N-degrons is the control of protein quality. In bacteria, the rate of polypeptide chain elongation is nearly an order of magnitude higher than in eukaryotes. We suggest that the faster emergence of nascent proteins from bacterial ribosomes is one mechanistic and evolutionary reason for the pretranslational design of bacterial fMet/N-degrons, in contrast to the cotranslational design of analogous Ac/N-degrons in eukaryotes.