Defining reference intervals for a serum growth differentiation factor-15 (GDF-15) assay in a Caucasian population and its potential utility in diabetic kidney disease (DKD).

BACKGROUND: Growth differentiation factor-15 (GDF-15), a stress responsive cytokine, is a promising biomarker of renal functional decline in diabetic kidney disease (DKD). This study aimed primarily to establish normative data and secondarily to evaluate the potential utility of GDF-15 in DKD using Roche Diagnostics electrochemiluminescence immunoassay (ECLIA) in an Irish Caucasian population. METHODS: Following informed consent, 188 healthy volunteers and 128 participants with diabetes (72 with and 56 without DKD) were recruited to a cross-sectional study. Baseline demographics, anthropometric measurements and laboratory measurements were recorded. Blood for GDF-15 measurement was collected into plain specimen tubes kept at room temperature and processed (centrifugation, separation of serum, freezing at -80 °C) within 1 h of phlebotomy pending batch analyses. Reference intervals were determined using the 2.5th and 97.5th percentiles for serum GDF-15 concentration. RESULTS: Of 188 healthy participants, 63 failed to meet study inclusion criteria. The reference interval for serum GDF-15 was 399 ng/L (90% confidence interval [CI]: 399-399) - 1335 ng/L (90% CI: 1152-1445). Receiver operator characteristics (ROC) curve analysis for DKD determined the area under the ROC curve to be 0.931 (95% CI: 0.893-0.959; p<0.001). The optimum GDF-15 cutoff for predicting DKD was >1136 ng/L providing a diagnostic sensitivity and specificity of 94.4% and 79%, respectively, and positive likelihood ratio of 4.5:1 (95% CI: 3.4-6.0). CONCLUSIONS: The reference interval for serum GDF-15 in a healthy Irish Caucasian population using Roche Diagnostics ECLIA was established and a preliminary determination of the potential of GDF-15 as a screening test for DKD was made. Further prospective validation with a larger DKD cohort will be required before the cutoff presented here is recommended for clinical use.

Maintaining glucose integrity ex-vivo: Impact of preanalytical specimen handling.

BACKGROUND: Adopting the WHO protocol for glucose analysis is arguably impractical in the routine clinical setting. Deviations may develop due to a lack of understanding regarding the impact of glycolysis on the accuracy of results. AIM: We sought to assess the stability of glucose in two different blood collection tubes (BCT), BD Vacutainer® FX 'Fl-Ox' and Greiner Vacuette® FC-Mix 'FC-Mix' stored at room temperature (RT:18-22°C) and 4°C over 8.5 days. METHOD: Each participant provided venous whole blood collected into 51 BCTs; 'Fl-Ox' (n = 26) and 'FC-Mix' (n = 25). One Fl-Ox sample from each participant was handled according to the WHO recommended method. The remaining BCTs were stored at 4°C/RT prior to analyses at designated study timepoints. Glucose was measured using the hexokinase assay on the Cobas® 8000 platform. RESULTS: Participants (n = 8, Male = 2) were aged 24-56 years. Plasma glucose measured in FI-Ox BCTs according to the WHO sample-handling method had a median concentration of 5.73 mmol/L (Range: 5.39-10.37 mmol/L). Glucose decreased by greater than minimal difference (>0.26 mmol/L) in blood collected into Fl-Ox and stored @4°C/RT within 24 h of phlebotomy. FC-Mix BCT maintained glucose <0.26 mmol/L @4°C over a period of 8.5 days and up to 4 days @RT when compared to the WHO recommended method. CONCLUSION: Glucose in FC-Mix BCT stored @4°C demonstrated the best agreement with results determined using the WHO specifications. When FC-Mix tubes were stored @RT, glucose was stable for 4 days. These findings suggest that the FC-Mix BCT effectively inhibits glycolysis and should be introduced into routine clinical practice.

Reference intervals for commonly requested biochemical and haematological parameters in a healthy Irish adult Caucasian population.

INTRODUCTION: In laboratory medicine, reference intervals (RIs) are key decision support tools used to guide the clinical interpretation of numerical test results. Best practice suggests each laboratory establishes RIs in the local population prior to introducing an assay into routine clinical practice. AIM: The aim of this study was to define RIs for frequently requested biochemical/haematological parameters in a healthy adult Irish Caucasian population. METHODS: A cross-sectional study of non-pregnant apparently healthy volunteers was conducted. Baseline demographics, anthropometric and laboratory measurements were recorded. In total, 37 commonly requested biochemical (serum, n = 26) and haematological (venous blood, n = 11) ISO15189:2012 accredited tests were analysed, using the Roche Cobas® Sebia Capillarys 3 Tera and Siemens Advia® 2120i platforms following standard operating procedures. RIs were defined according to the International Federation of Clinical Chemistry (IFCC) recommended method. RESULTS: Of 208 apparently healthy volunteers, 76 failed to meet the study inclusion criteria. The reference population comprised of 132 participants (males: n = 65, 49.2%) with a median age of 29.7 (18.1-62.2) years. RIs for the majority of biochemical/haematological parameters were broadly in accord with those provided by Pathology Harmony (UK)/Irish RI Harmonisation Project and the manufacturer Roche Diagnostics. However, the established RI defined for HbA1c: 27-37 mmol/mol was markedly different from that quoted nationally, HbA1c: 20-42 mmol/mol. CONCLUSION: Normative biological intervals established in a healthy adult Irish population for 37 commonly requested biochemical/haematological parameters will be a valuable aid to result interpretation in clinical laboratories after appropriate verification in accordance with ISO 15189: 2012.

Pathogenicity and virulence of the liver flukes Fasciola hepatica and FasciolaGigantica that cause the zoonosis Fasciolosis.

Fasciolosis caused by the liver flukes Fasciola hepatica and Fasciola gigantica is one of the most important neglected parasitic diseases of humans and animals. The ability of the parasites to infect and multiply in their intermediate snail hosts, and their adaptation to a wide variety of mammalian definitive hosts contribute to their high transmissibility and distribution. Within the mammalian host, the trauma caused by the immature flukes burrowing through the liver parenchyma is associated with most of the pathogenesis. Similarly, the feeding activity and the physical presence of large flukes in the bile ducts can lead to anemia, inflammation, obstruction and cholangitis. The high frequency of non-synonymous polymorphisms found in Fasciola spp. genes allows for adaptation and invasion of a broad range of hosts. This is also facilitated by parasite's excretory-secretory (ES) molecules that mediate physiological changes that allows their establishment within the host. ES contains cathepsin peptidases that aid parasite invasion by degrading collagen and fibronectin. In the bile ducts, cathepsin-L is critical to hemoglobin digestion during feeding activities. Other molecules (peroxiredoxin, cathepsin-L and Kunitz-type inhibitor) stimulate a strong immune response polarized toward a Treg/Th2 phenotype that favors fluke's survival. Helminth defense molecule, fatty acid binding proteins, Fasciola-specific glycans and miRNAs modulate host pro-inflammatory responses, while antioxidant scavenger enzymes work in an orchestrated way to deter host oxidant-mediated damage. Combining these strategies Fasciola spp. survive for decades within their mammalian host, where they reproduce and spread to become one of the most widespread zoonotic worm parasites in the world.

Autonomous Non Antioxidant Roles for Fasciola hepatica Secreted Thioredoxin-1 and Peroxiredoxin-1.

Trematode parasites of the genus Fasciola are the cause of liver fluke disease (fasciolosis) in humans and their livestock. Infection of the host involves invasion through the intestinal wall followed by migration in the liver that results in extensive damage, before the parasite settles as a mature egg-laying adult in the bile ducts. Genomic and transcriptomic studies revealed that increased metabolic stress during the rapid growth and development of F. hepatica is balanced with the up-regulation of the thiol-independent antioxidant system. In this cascade system thioredoxin/glutathione reductase (TGR) reduces thioredoxin (Trx), which then reduces and activates peroxiredoxin (Prx), whose major function is to protect cells against the damaging hydrogen peroxide free radicals. F. hepatica expresses a single TGR, three Trx and three Prx genes; however, the transcriptional expression of Trx1 and Prx1 far out-weighs (>50-fold) other members of their family, and both are major components of the parasite secretome. While Prx1 possesses a leader signal peptide that directs its secretion through the classical pathway and explains why this enzyme is found freely soluble in the secretome, Trx1 lacks a leader peptide and is secreted via an alternative pathway that packages the majority of this enzyme into extracellular vesicles (EVs). Here we propose that F. hepatica Prx1 and Trx1 do not function as part of the parasite's stress-inducible thiol-dependant cascade, but play autonomous roles in defence against the general anti-pathogen oxidative burst by innate immune cells, in the modulation of host immune responses and regulation of inflammation.