Assessment of Commercially Available Immunoassays to Measure Glucocorticoid Metabolites in African Grey Parrot (Psittacus Erithacus) Droppings: A Ready Tool for Non-Invasive Monitoring of Stress

Simple Summary

The African Grey Parrot is a very popular bird commonly found in zoological collections. However, captivity can prevent it from meeting its natural needs and so become an ongoing stressor, leading sometimes to clinical and/or behavioral disorders. Non-invasive forms of stress assessment are of definite interest for monitoring welfare in captive bird populations. One notable stress outcome is the excretion of glucocorticoid metabolites (from the stress hormone corticosterone) in droppings. The aim of this study was to carefully assess methods of glucocorticoid metabolites extraction and measurement in droppings from African Grey Parrots. Several extraction and enzyme immunoassays procedures were tested, based on the evaluation of analytical quality parameters and biological relevance. The best procedure was found to be a combination of a 60% methanol extraction with the use of a commercial corticosterone enzyme immunoassay. To determine whether this method was suitable for assessing different stress levels, a significant correlation with another reliable stress marker in birds, the Heterophil: Lymphocyte Ratio, was evidenced. This method can thus be used to evaluate stress in African Gray Parrots in a non-invasive way and help to monitor their welfare in zoo populations for instance.

Abstract

Despite being undomesticated, African Grey Parrots (Psittacus erithacus) are commonly found in captivity, in zoos or as pets. Captivity can be an ongoing stressor. Non-invasive glucocorticoid metabolites (GCM) measurements from bird droppings are of interest for assessing stress but require careful evaluation in each newly studied species. This study describes the assessment of such methods for Psittacus erithacus to provide tools for evaluating stress and monitoring welfare. We evaluated 12 method combinations of GCM extraction and enzyme immunoassay (EIA) from a pool of African Grey Parrot droppings, through the validation of several analytical parameters. Then, Heterophil: Lymphocyte Ratios (HLR), another reliable stress marker, were determined and correlated to individual dropping GCM concentrations for 29 birds to determine whether the method is biologically relevant. We found that the best procedure to measure GCM in African Grey Parrot droppings is a combination of 60% methanol extraction measured using a Corticosterone EIA kit (Cayman Chemical Company) from fresh or dry droppings. The establishment of a significant correlation (Pearson coefficient correlation = 0.48; p = 0.0082) between HLR and GCM in the studied population confirmed the method biological relevance. This method can thus be applied to assess stress in Psittacus erithacus and support welfare monitoring in zoo populations.

Biomarkers in early-phase trials: fundamental issues

Biomarkers are frequently being included in early-phase clinical trials. This article is meant to introduce clinical investigators to the fundamentals of choosing a biomarker test for use in an early phase trial. Steps to consider are briefly outlined including defining the role of the biomarker in the early phase trial; selecting a fit-for-purpose biomarker test and laboratory; describing the test procedures; carrying out analytical validation testing appropriate for the research objectives and the risk involved in the trial; implementing the test in the trial; and planning for the future. Examples illustrate analytical validation approaches in the context of typical biomarker roles. The importance of collaboration between clinical investigators and laboratory researchers is emphasized.

Validation of a Commercially Available Enzyme ImmunoAssay for the Determination of Oxytocin in Plasma Samples from Seven Domestic Animal Species

The neurohormone oxytocin (OT) has a broad range of behavioral effects in mammals. It modulates a multitude of social behaviors, e.g., affiliative and sexual interactions. Consequently, the OT role in various animal species is increasingly explored. However, several issues have been raised regarding the peripheral OT measurement. Indeed, various methods have been described, leading to assay discrepancies and inconsistent results. This highlights the need for a recognized and reliable method to measure peripheral OT. Our aim was to validate a method combining a pre-extraction step, previously demonstrated as essential by several authors, and a commercially available enzyme immunoassay (EIA) for OT measurement, using plasma from seven domestic species (cat, dog, horse, cow, pig, sheep, and goat). The Oxytocin EIA kit (EnzoLifeSciences) was used to assay the solid-phase extracted samples following the manufacturer's instructions with slight modifications. For all species except dogs and cats, concentration factors were applied to work above the kit's sensitivity (15 pg/ml). To validate the method, the following performance characteristics were evaluated using Validation Samples (VS) at various concentrations in each species: extraction efficiency via spiking tests and intra- and inter-assay precision, allowing for the calculation of total errors. Parallelism studies to assess matrix effects could not be performed because of too low basal concentrations. Quantification ranges and associated precision profiles were established to account for the various OT plasma concentrations in each species. According to guidelines for bioanalytical validation of immunoassays, the measurements were sufficiently precise and accurate in each species to achieve a total error ≤30% in each VS sample. In each species, the inter-assay precision after 3 runs was acceptable, except in low concentration samples. The linearity under dilution of dogs and cats' samples was verified. Although matrix effects assessments are lacking, our results indicate that OT plasma levels can reliably be measured in several domestic animal species by the method described here. Studies involving samples with low OT plasma concentrations should pay attention to reproducibility issues. This work opens new perspectives to reliably study peripheral OT in a substantial number of domestic animal species in various behavioral contexts.

Analytical validation of a 12-gene molecular test for the prediction of distant recurrence in breast cancer

Aim:

To validate the analytical performance of a 12-gene molecular assay that predicts distant recurrence for early-stage ER+/HER2- invasive breast cancer as run within a central reference laboratory.

Materials & methods:

Formalin-fixed paraffin-embedded breast resections were evaluated by quantitative reverse transcription polymerase chain reaction for the expression of eight target genes, three housekeeper genes and one control gene to assess for DNA contamination.

Results:

The assay results were highly correlated with a validated reference laboratory. The assay had a broad linear range for input RNA, with similar amplicon efficiencies for target and housekeeper genes. The assay test was highly reproducible, with comparable inter- and intrabatch precision to the reference laboratory.

Conclusion:

These studies demonstrate that the 12-gene molecular assay is highly robust and accurate.

Several tests have been developed to aid in breast cancer treatment decisions by assessing the likelihood that an individual’s breast cancer will recur. One such test is a 12-gene molecular assay. This test provides a clinical score that combines molecular information from genes within the tumor with clinical information to determine whether a breast cancer is at high or low risk of recurrence. The data presented here show that this test is very reproducible and robust, making it appropriate and reliable for clinical use.

Clinical application of a cancer genomic profiling assay to guide precision medicine decisions

Aim:

Develop and apply a comprehensive and accurate next-generation sequencing based assay to help clinicians to match oncology patients to therapies.

Materials & methods:

The performance of the CANCERPLEX^® assay was assessed using DNA from well-characterized routine clinical formalin-fixed paraffin-embedded (FFPE) specimens and cell lines.

Results:

The maximum sensitivity of the assay is 99.5% and its accuracy is virtually 100% for detecting somatic alterations with an allele fraction of as low as 10%. Clinically actionable variants were identified in 93% of patients (930 of 1000) who underwent testing.

Conclusion:

The test's capacity to determine all of the critical genetic changes, tumor mutation burden, microsatellite instability status and viral associations has important ramifications on clinical decision support strategies, including identification of patients who are likely to benefit from immune checkpoint blockage therapies.

The analytical validation of the Oncotype DX Recurrence Score assay

In vitro diagnostic multivariate index assays are highly complex molecular assays that can provide clinically actionable information regarding the underlying tumour biology and facilitate personalised treatment. These assays are only useful in clinical practice if all of the following are established: analytical validation (i.e., how accurately/reliably the assay measures the molecular characteristics), clinical validation (i.e., how consistently/accurately the test detects/predicts the outcomes of interest), and clinical utility (i.e., how likely the test is to significantly improve patient outcomes). In considering the use of these assays, clinicians often focus primarily on the clinical validity/utility; however, the analytical validity of an assay (e.g., its accuracy, reproducibility, and standardisation) should also be evaluated and carefully considered. This review focuses on the rigorous analytical validation and performance of the Oncotype DX^® Breast Cancer Assay, which is performed at the Central Clinical Reference Laboratory of Genomic Health, Inc. The assay process includes tumour tissue enrichment (if needed), RNA extraction, gene expression quantitation (using a gene panel consisting of 16 cancer genes plus 5 reference genes and quantitative real-time RT-PCR), and an automated computer algorithm to produce a Recurrence Score^® result (scale: 0–100). This review presents evidence showing that the Recurrence Score result reported for each patient falls within a tight clinically relevant confidence interval. Specifically, the review discusses how the development of the assay was designed to optimise assay performance, presents data supporting its analytical validity, and describes the quality control and assurance programmes that ensure optimal test performance over time.

Analytic Validation of the Automated Bone Scan Index as an Imaging Biomarker to Standardize Quantitative Changes in Bone Scans of Patients with Metastatic Prostate Cancer

A reproducible and quantitative imaging biomarker is needed to standardize the evaluation of changes in bone scans of prostate cancer patients with skeletal metastasis. We performed a series of analytic validation studies to evaluate the performance of the automated bone scan index (BSI) as an imaging biomarker in patients with metastatic prostate cancer.

METHODS

Three separate analytic studies were performed to evaluate the accuracy, precision, and reproducibility of the automated BSI. Simulation study: bone scan simulations with predefined tumor burdens were created to assess accuracy and precision. Fifty bone scans were simulated with a tumor burden ranging from low to high disease confluence (0.10-13.0 BSI). A second group of 50 scans was divided into 5 subgroups, each containing 10 simulated bone scans, corresponding to BSI values of 0.5, 1.0, 3.0, 5.0, and 10.0. Repeat bone scan study: to assess the reproducibility in a routine clinical setting, 2 repeat bone scans were obtained from metastatic prostate cancer patients after a single 600-MBq (99m)Tc-methylene diphosphonate injection. Follow-up bone scan study: 2 follow-up bone scans of metastatic prostate cancer patients were analyzed to determine the interobserver variability between the automated BSIs and the visual interpretations in assessing changes. The automated BSI was generated using the upgraded EXINI bone(BSI) software (version 2). The results were evaluated using linear regression, Pearson correlation, Cohen κ measurement, coefficient of variation, and SD.

RESULTS

Linearity of the automated BSI interpretations in the range of 0.10-13.0 was confirmed, and Pearson correlation was observed at 0.995 (n = 50; 95% confidence interval, 0.99-0.99; P < 0.0001). The mean coefficient of variation was less than 20%. The mean BSI difference between the 2 repeat bone scans of 35 patients was 0.05 (SD = 0.15), with an upper confidence limit of 0.30. The interobserver agreement in the automated BSI interpretations was more consistent (κ = 0.96, P < 0.0001) than the qualitative visual assessment of the changes (κ = 0.70, P < 0.0001) was in the bone scans of 173 patients.

CONCLUSION

The automated BSI provides a consistent imaging biomarker capable of standardizing quantitative changes in the bone scans of patients with metastatic prostate cancer.

[Analytical validation of a chromatographic method dedicated to search and identify natural and semi-synthetic opiates]

The identification of a product absorbed by an opiate consumer is sometimes problematic since there is no specific biomarker for all molecules. We developed an ultra-high pressure liquid chromatography coupled to tandem mass spectrometry technique which allows the identification and the quantification of 25 opiates in plasma. The sample preparation consists in a solid-phase extraction on Oasis MCX cartridges (Waters). The method has been validated according to FDA criteria completely for 21 substances and with some reservations for the remaining 4 analytes. This method has been applied to 80 patients treated at the University Hospital of Liege for whom the screening of opiates was positive. The identification of the product consumed was effective in 86% of cases.

Improvement and validation of d-xylose determination in urine and serum as a new tool for the noninvasive evaluation of lactase activity in humans

BACKGROUND

The phloroglucinol assay is the current method for d-xylose determination in urine/plasma/serum. However, its sensitivity is limited when low amounts of d-xylose are to be measured, such as in the noninvasive evaluation of intestinal lactase with 4-galactosylxylose (gaxilose). An improved assay was therefore needed.

METHODS

We developed and validated a modified version of the phloroglucinol-based assay for quantification of d-xylose in urine/serum samples. A method for gaxilose determination by gas chromatography (GC) was also optimized.

RESULTS

Linearity ranged from 0.125 to 5.0 mg/l (5-200 mg/l in original sample). Accuracy at LOQ (0.125 mg/l) was 0.97/2.49% in spiked urine/serum; for other quality controls (QC), it was <1.27%. Intra- and interassay precision at LOQ were 6.02% and 6.45% for urine, and 8.86% and 10.00%, respectively, for serum; for other QC, precision was <2.15%. Linearity of gaxilose determination by GC was 3.90-195.17 for urine and 9.75-195.17 mg/l for serum with acceptable sensitivity and reproducibility. The method proved adequate for the d-xylose determination in healthy and hypolactasic subjects after oral administration of gaxilose.

CONCLUSIONS

The modified method provides high sensitivity and robustness for d-xylose quantification in urine/serum for routine clinical use especially in the noninvasive diagnosis of intestinal lactase deficiency with the gaxilose test.

Criteria for the use of omics-based predictors in clinical trials: explanation and elaboration

High-throughput 'omics' technologies that generate molecular profiles for biospecimens have been extensively used in preclinical studies to reveal molecular subtypes and elucidate the biological mechanisms of disease, and in retrospective studies on clinical specimens to develop mathematical models to predict clinical endpoints. Nevertheless, the translation of these technologies into clinical tests that are useful for guiding management decisions for patients has been relatively slow. It can be difficult to determine when the body of evidence for an omics-based test is sufficiently comprehensive and reliable to support claims that it is ready for clinical use, or even that it is ready for definitive evaluation in a clinical trial in which it may be used to direct patient therapy. Reasons for this difficulty include the exploratory and retrospective nature of many of these studies, the complexity of these assays and their application to clinical specimens, and the many potential pitfalls inherent in the development of mathematical predictor models from the very high-dimensional data generated by these omics technologies. Here we present a checklist of criteria to consider when evaluating the body of evidence supporting the clinical use of a predictor to guide patient therapy. Included are issues pertaining to specimen and assay requirements, the soundness of the process for developing predictor models, expectations regarding clinical study design and conduct, and attention to regulatory, ethical, and legal issues. The proposed checklist should serve as a useful guide to investigators preparing proposals for studies involving the use of omics-based tests. The US National Cancer Institute plans to refer to these guidelines for review of proposals for studies involving omics tests, and it is hoped that other sponsors will adopt the checklist as well.

Laboratory aspects of circulating α-Klotho

BACKGROUND

α-Klotho is a protein mainly produced in the kidney. Its circulating form has been suggested to link renal damage and distant tissue pathology. As three assays to measure α-Klotho became commercially available, we performed an evaluation of these commercially available Klotho assays.

METHODS

We studied within-run variation, between-run variation, matrix effects, linearity, and recovery of added recombinant human Klotho in the α-Klotho assays of IBL (IBL International GmbH, Hamburg, Germany), Cusabio (Cusabio Biotech, Wuhan, China) and USCN (USCN life Science, Inc., Wuhan, China) using both serum and ethylenediaminetetraacetic acid plasma.

RESULTS

Within run variation was 4, 13 and 32% for the IBL, Cusabio and USCN assay, respectively. Agreement between serum and EDTA plasma was good in the IBL assay, but poor in the USCN and Cusabio assays however improved after modifications in the Cusabio assay. Standardization and agreement between assays was poor.

CONCLUSIONS

The commercially available methods for the measurement of α-Klotho differ in quality. Some of the manufacturers should improve their assays in order to produce accurate results so that reliable conclusions can be drawn from studies in which these assays are used.