Pre-analytical Conditions Research Articles

Timing of Blood Sample Processing Affects the Transcriptomic and Epigenomic Profiles in CD4+ T-cells of Atopic Subjects.

Optimal pre-analytical conditions for blood sample processing and isolation of selected cell populations for subsequent transcriptomic and epigenomic studies are required to obtain robust and reproducible results. This pilot study was conducted to investigate the potential effects of timing of CD4+ T-cell processing from peripheral blood of atopic and non-atopic adults on their transcriptomic and epigenetic profiles. Two heparinized blood samples were drawn from each of three atopic and three healthy individuals. For each individual, CD4+ T-cells were isolated from the first blood sample within 2 h (immediate) or from the second blood sample after 24 h storage (delayed). RNA sequencing (RNA-Seq) and histone H3K27 acetylation chromatin immunoprecipitation sequencing (ChIP-Seq) analyses were performed. A multiplicity of genes was shown to be differentially expressed in immediately processed CD4+ T-cells from atopic versus healthy subjects. These differences disappeared when comparing delayed processed cells due to a drastic change in expression levels of atopy-related genes in delayed processed CD4+ T-cells from atopic donors. This finding was further validated on the epigenomic level by examining H3K27 acetylation profiles. In contrast, transcriptomic and epigenomic profiles of blood CD4+ T-cells of healthy donors remained rather unaffected. Taken together, for successful transcriptomics and epigenomics studies, detailed standard operation procedures developed on the basis of samples from both healthy and disease conditions are implicitly recommended.

Defining blood gas analysis stability limits across five sample types

Accurate reporting of blood gas samples is dependent upon following proper preanalytical sample handling requirements though there is variation for sample acceptability criteria across institutions. We examined five common sample types (arterial, venous, umbilical arterial, umbilical venous and capillary) stored at either room temperature or on crushed ice in a time series (0, 15, 30, 45, 60, 90, 180, 240 min) and applied local regulatory and/or institutional allowable performance limits to determine the need for cold preservation and/or maximum stability time for pH, pO2, pCO2, glucose, lactate, sodium, potassium, chloride, and ionized calcium where applicable in each sample type. Although changes in sample pO2 and/or lactate values were responsible, in part or in whole, for surpassing the allowable limits in nearly all sample types analyzed, this was not uniformly observed across sample types within the typical time limits that are referenced in literature. Furthermore, we demonstrated that cold preservation may not ubiquitously provide longer stability for blood gas specimens and this is dependent on the sample type and analyte in question. Nevertheless, these results demonstrate the known instability of pO2 and lactate and suggest that it may be possible to simplify the monitoring of preanalytical conditions by first evaluating pO2 and lactate in patient blood gas samples if applicable.

Serum GFAP- reference interval and preanalytical properties in Danish adults.

Glial fibrillary acidic protein (GFAP) is a promising biomarker that could potentially contribute to diagnosis and prognosis in neurological diseases. The biomarker is approaching clinical use but the reference interval for serum GFAP remains to be established, and knowledge about the effect of preanalytical factors is also limited. Serum samples from 371 apparently healthy reference subjects, 21-90 years of age, were measured by a single-molecule array (Simoa) assay. Continuous reference intervals were modelled using non-parametric quantile regression and compared with traditional age-partitioned non-parametric reference intervals established according to the Clinical and Laboratory Standards Institute (CLSI) guideline C28-A3. The following preanalytical conditions were also examined: stability in whole blood at room temperature (RT), stability in serum at RT and-20°C, repeated freeze-thaw cycles, and haemolysis. The continuous reference interval showed good overall agreement with the traditional age-partitioned reference intervals of 25-136ng/L, 34-242ng/L, and 5-438ng/L for the age groups 20-39, 40-64, and 65-90 years, respectively. Both types of reference intervals showed increasing levels and variability of serum GFAP with age. In the preanalytical tests, the mean changes from baseline were 2.3% (95% CI:-2.4%, 6.9%) in whole blood after 9h at RT, 3.1% (95% CI:-4.5%, 10.7%) in serum after 7days at RT, 10.4% (95% CI:-6.0%, 26.8%) in serum after 133days at-20°C, and 10.4% (95% CI: 9.5%, 11.4%) after three freeze-thaw cycles. The study establishes age-dependent reference ranges for serum GFAP in adults and demonstrates overall good stability of the biomarker.

Phosphatidylethanolamine Binding Protein1 (PEBP1) in Alzheimer's Disease: ELISA Development and Clinical Validation.

Background: Phosphatidylethanolamine binding protein 1 (PEBP1) is a multifunctional protein, mainly known for its specific binding of phosphatidylethanolamine and the ability to suppress the Raf1-MAPK pathway. Its potential role as an Alzheimer’s disease (AD) biomarker has been proposed in several studies. However, evaluation of its discriminative value in clinical cohorts is missing.Objective:We aimed to develop a new immunoassay for the measurement of PEBP1 in cerebrospinal fluid (CSF) and assess the possible role of this protein as AD biomarker.Methods:We developed a sandwich enzyme-linked immunosorbent assay (ELISA) for detection of PEBP1 in CSF and performed a technical and a clinical validation on two well-characterized cohorts. The first cohort included 14 mild cognitive impairment due to AD (MCI-AD) and 11 other neurological diseases (OND) patients. The second, larger cohort, included 25 MCI-AD, 29 AD dementia (AD-dem), and 21 OND patients.Results:PEBP1 is highly sensitive to pre-analytical conditions, especially to prolonged storage at room temperature or 4°C. Analysis of the first cohort showed a trend of an increase of PEBP1 level in MCI-AD patients versus OND subjects. Analysis of the second cohort did not show significant differences among diagnostic groups. Weak, positive correlation was found between CSF PEBP1 and t-tau, p-tau, and Aβ40 in the AD-dem group.Conclusion:A novel ELISA for the detection of PEBP1 in CSF was developed. Further research is needed to assess the potential of PEBP1 in AD diagnostics. The observed dependence of the PEBP1 signal on operating procedures encourages its potential application as CSF quality control.

Evaluation of the impact of pre-analytical conditions on sample stability for the detection of SARS-CoV-2 RNA

Demand for accurate SARS-CoV-2 diagnostics is high. Most samples in the UK are collected in the community and rely on the postal service for delivery to the laboratories. The current recommendation remains that swabs should be collected in Viral Transport Media (VTM) and transported with a cold chain to the laboratory for RNA extraction and RT-qPCR. This is not always possible. We aimed to test the stability of SARS-CoV-2 RNA subjected to different pre-analytical conditions. Swabs were dipped into PBS containing cultured SARS-CoV-2 and placed in either a dry tube or a tube containing either normal saline or VTM. The tubes were then stored at different temperatures (20–50 °C) for variable periods (8 h to 5 days). Samples were tested by RT-qPCR targeting SARS-CoV-2 E gene. VTM outperformed swabs in saline and dry swabs in all conditions. Samples in VTM were stable, independent of a cold chain, for 5 days, with a maximum increase in cycle threshold (Ct) of 1.34 when held at 40 °C. Using normal saline as the transport media resulted in a loss of sensitivity (increased Ct) over time and with increasing temperature (up to 7.8 cycles compared to VTM). SARS-CoV-2 was not detected in 3/9 samples in normal saline when tested after 120 h incubation. Transportation of samples in VTM provides a high level of confidence in the results despite the potential for considerable, uncontrolled variation in temperature and longer transportation periods. False negative results may be seen after 96 h in saline and viral loads will appear lower.

Impact of Preanalytical Factors on Calprotectin Concentration in Stool: A Multiassay Comparison.

Measuring calprotectin concentration in stool is increasingly important in monitoring disease activity and treatment response in inflammatory bowel disease. This study evaluates the impact of preanalytical storage conditions on reliability of calprotectin testing using 5 different calprotectin immunoassays. Aliquots of homogenized fresh fecal samples in untreated or extracted form were stored at room temperature or 4°C. Calprotectin concentration was measured day 0 to 4 and 8. Five different immunoassays and accompanying extraction buffers were used (CALiaGold, Phadia EliA, Bühlmann fCal turbo, ELISA Bühlmann, Inova Quanta Flash). Repeated measurements of change from baseline calprotectin levels over time were analyzed using a mixed model analysis. Calprotectin concentrations declined over time under all preanalytical conditions with all assays, except for extracted feces stored at 4°C. The rate of decline was greatest in untreated stool kept at room temperature, reaching significant difference from baseline already after 1 day (P < 0.001). In extracted feces kept at room temperature, significant difference from baseline was reached after 2 days, and in untreated feces at 4°C, after 4 days. However, the results differed significantly between assays. After 4 days of storage at room temperature, the mean calprotectin decline from baseline differed between 30% and 60%, dependent on the assay used. Fecal calprotectin concentration in stool samples declines over time, and the rate of decline is greater at higher temperatures. In extracted feces stored at 4°C, calprotectin is most stable. It is assay-dependent how long extracted feces stored at 4°C give reliable test results.

Exploration biochimique de la médullosurrénale

AbstractCatecholamines (epinephrine and norepinephrine) are hormones that regulate arterial pressure and are neurotransmitters of sympathetic autonomous nervous system. They are secreted in excess by chromaffin tumors of adrenal medulla (phaeochromocytoma) or sympathetic lymph nodes (paraganglioma). The catecholamines as well as their metabolites (metanephrines, vanillylmandelic acid and homovanillic acid), and also dopamine, are measured in both plasma and urines by assays based on separation by high performance liquid chromatography (HPLC) and often identified by tandem mass spectrometry (MS/MS). Pre-analytic conditions are difficult because they should not stimulate secretion of catecholamines. Actual recommendations request first measurement of total metanephrines in urines although HPLC-MS/MS can measure separately free forms in both plasma and urines. Chromogranin A allows easily screening, but not yet available. Positive diagnosis and therapeutic nursing of these tumors need the all analytical arsenal from metanephrines to catecholamines their-self.

Storage conditions, sample integrity, interferences, and a decision tool for investigating unusual high-sensitivity cardiac troponin results

The current definition of high-sensitivity cardiac troponin (hs-cTn) assays is laboratory-based and their analytical attributes and characteristics have drawn significant attention in the literature at least partly due to the lower concentration cut-offs and changes in concentrations (i.e., deltas) employed in different algorithms and pathways to manage patient care. We propose that pre-analytical conditions such as sample type, storage conditions, and other interferences may also have a significant impact on hs-cTn concentrations and clinical management. The purpose of this literature review is to provide a summary of important pre-analytical and interference studies affecting hs-cTn concentrations. A breakdown of the literature for the major diagnostic companies providing core laboratory instrumentation (i.e., Abbott, Beckman, Ortho, Roche, and Siemens) is also provided. Finally, three cases are highlighted where knowledge of pre-analytical factors aids the hs-cTn clinically discordant investigations. This review highlights the importance of pre-analytical variables, especially storage condition, sample handling, and blood tubes used (i.e., sample type) when interpreting hs-cTn assays. Additional studies are needed to further elaborate on pre-analytical variables (i.e., centrifugation, sample type, stability) and interferences for all hs-cTn assays in clinical use, as knowledge of these variables may aid in hs-cTn clinically discordant investigations.

Abstract 2791: Integrating biospecimen science approaches into clinical assay development-PAR 22-049

Abstract Introduction to the problem: Biospecimens are the essential starting materials for the biomarker assays that enable precision medicine. Biospecimen preanalytical factors can directly influence molecular results from assays conducted for basic research, biomarker discovery, and biomarker validation, and can also influence the development of validated clinical assays. The U.S. National Cancer Institute (NCI) Biorepositories and Biospecimen Research Branch supports extramural research as a part of this FOA to investigate and mitigate preanalytical challenges facing clinical assay development and analytical validation in a variety of biospecimen types. The overall goal of this initiative is to expedite biomarker clinical assay development through evidence based standardization of biospecimen handling practices. The work is centered on emerging and clinically relevant biomarker assays conducted on a variety of molecular platforms. Proposed solution and methods: Researchers may investigate tissue and fluid biospecimens including core biopsies, fine needle aspirates, tissue exudates, blood, urine, saliva, breast milk, feces, sweat, CSF, and pleural and esophageal aspirates. Investigator designed experiments explore how different biospecimen preanalytical conditions affect biomarkers in a clinical setting. To date, ten grants have been funded. The grants address important areas in biospecimen science in both liquid and solid biopsy biopsies in breast cancer, glioblastomas, lung cancer, bladder cancer, prostate cancer, cutaneous and peripheral T cell lymphoma. Investigators can collaborate with each other and with the NCI, FDA and NIST through the U01 funding mechanism. Conclusions: The results from this research program will elucidate how analytical quantification of clinically relevant biomarkers is affected by patient context factors, variation in biospecimen collection, processing, and storage procedures, and how such effects can be mitigated to improve the development, performance and accuracy of clinical biomarker assays utilized in clinical research and patient care. The receipt dates for this program, PAR 22 049 in 2022, are January 11, 2022, June 7th, 2022, and September 13th, 2022. Citation Format: Lokesh Agrawal, Abhi Rao, Ping Guan, Miguel Ossandon, Helen Moore. Integrating biospecimen science approaches into clinical assay development-PAR 22-049 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2791.

Acidification of 24-hour urine in urolithiasis risk testing: An obsolete relic?

BackgroundRecommendations on the optimal preservation of 24 h urine for the metabolic work-up in urolithiasis patients are very heterogeneous. In case two such tests with different storage condition recommendations are being analysed, multiple collections would be needed, challenging especially elderly and very young patients. We therefore aimed to evaluate the stability of urine constituents under different storage conditions. Material and methodsWe collected urine samples from ten healthy volunteers and prepared aliquots to be stored either at room temperature or 4 °C. Some aliquots were preserved using hydrochloric acid prior to storage, some thereafter, some using the BD Urine preservation tube and some were not preserved at all. Storage duration was 0, 24, 48 or 72 h. In all samples calcium, magnesium, phosphorus, creatinine, oxalate, citrate and uric acid were measured and compared to the according reference sample. ResultsWe could not find any significant deviation for any of the analytes and preanalytical treatment conditions compared to the associated reference sample. ConclusionPreservation of 24 h urine for the metabolic evaluation in stone formers might not be necessary for sample storage up to 72 h.

Importance of cerebrospinal fluid storage conditions for the Alzheimer's disease diagnostics on an automated platform.

Alzheimer's disease (AD) is considered the most common cause of dementia in older people. Cerebrospinal fluid (CSF) Aβ1-42, Aβ1-40, total Tau (t-Tau), and phospho Tau (p-Tau) are important biomarkers for the diagnosis, however, they are highly dependent on the pre-analytical conditions. Our aim was to investigate the potential influence of different storage conditions on the simultaneous quantification of these biomarkers in a fully-automated platform to accommodate easier pre-analytical conditions for laboratories. CSF samples were obtained from 11 consecutive patients. Aβ1-42, Aβ1-40, p-Tau, and t-Tau were quantified using the LUMIPULSE G600II automated platform. Temperature and storage days significantly influenced Aβ1-42 and Aβ1-40 with concentrations decreasing with days spent at 4°C. The use of the Aβ1-42/Aβ1-40 ratio could partly compensate it. P-Tau and t-Tau were not affected by any of the tested storage conditions. For conditions involving storage at 4°C, a correction factor of 1.081 can be applied. Diagnostic agreement was almost perfect in all conditions. Cutoffs calculated in samples stored at-80°C can be safely used in samples stored at-20°C for 15-16days or up to two days at RT and subsequent freezing at-80°C. For samples stored at 4°C, cutoffs would require applying a correction factor, allowing to work with the certainty of reaching the same clinical diagnosis.

Assessing the quality of RNA isolated from human breast tissue after ambient room temperature exposure.

High quality human tissue is essential for molecular research, but pre-analytical conditions encountered during tissue collection could degrade tissue RNA. We evaluated how prolonged exposure of non-diseased breast tissue to ambient room temperature (22±1°C) impacted RNA quality. Breast tissue received between 70 to 190 minutes after excision was immediately flash frozen (FF) or embedded in Optimal Cutting Temperature (OCT) compound upon receipt (T0). Additional breast tissue pieces were further exposed to increments of 60 (T1 = T0+60 mins), 120 (T2 = T0+120 mins) and 180 (T3 = T0+180 mins) minutes of ambient room temperature before processing into FF and OCT. Total exposure, T3 (T0+180 mins) ranged from 250 minutes to 370 minutes. All samples (FF and OCT) were stored at -80°C before RNA isolation. The RNA quality assessment based on RNA Integrity Number (RIN) showed RINs for both FF and OCT samples were within the generally acceptable range (mean 7.88±0.90 to 8.52±0.66). No significant difference was observed when RIN at T0 was compared to RIN at T1, T2 and T3 (FF samples, p = 0.43, 0.56, 0.44; OCT samples, p = 0.25, 0.82, 1.0), or when RIN was compared between T1, T2 and T3. RNA quality assessed by quantitative real-time PCR (qRT-PCR) analysis of beta-actin (ACTB), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), cyclophilin A (CYPA), and porphobilinogen deaminase (PBGD) transcripts showed threshold values (Ct) that indicate abundant and intact target nucleic acid in all samples (mean ranging from 14.1 to 25.3). The study shows that higher RIN values were obtained for non-diseased breast tissue up to 190 minutes after resection and prior to stabilization. Further experimental exposure up to 180 minutes had no significant effect on RIN values. This study strengthens the rationale for assessing RIN and specific gene transcript levels as an objective method for determining how suitable RNA will be for a specific research purpose (“fit-for purpose”).

Sensitive Quantification of Cell-Free Tumor DNA for Early Detection of Recurrence in Colorectal Cancer.

The detection of plasma cell–free tumor DNA (ctDNA) is prognostic in colorectal cancer (CRC) and has potential for early prediction of disease recurrence. In clinical routine, ctDNA-based diagnostics are limited by the low concentration of ctDNA and error rates of standard next-generation sequencing (NGS) approaches. We evaluated the potential to increase the stability and yield of plasma cell–free DNA (cfDNA) for routine diagnostic purposes using different blood collection tubes and various manual or automated cfDNA extraction protocols. Sensitivity for low-level ctDNA was measured in KRAS-mutant cfDNA using an error-reduced NGS procedure. To test the applicability of rapid evaluation of ctDNA persistence in clinical routine, we prospectively analyzed postoperative samples of 67 CRC (stage II) patients. ctDNA detection was linear between 0.0045 and 45%, with high sensitivity (94%) and specificity (100%) for mutations at 0.1% VAF. The stability and yield of cfDNA were superior when using Streck BCT tubes and a protocol by Zymo Research. Sensitivity for ctDNA increased 1.5-fold by the integration of variant reads from triplicate PCRs and with PCR template concentration. In clinical samples, ctDNA persistence was found in ∼9% of samples, drawn 2 weeks after surgery. Moreover, in a retrospective analysis of 14 CRC patients with relapse during adjuvant therapy, we successfully detected ctDNA (median 0.38% VAF; range 0.18–5.04% VAF) in 92.85% of patients significantly prior (median 112 days) to imaging-based surveillance. Using optimized pre-analytical conditions, the detection of postoperative ctDNA is feasible with excellent sensitivity and allows the prediction of CRC recurrence in routine oncology testing.

Meals and Room Temperature Storage do not Significantly Affect Feasibility of Direct RT-PCR Tests for SARS-CoV-2 Using Saliva.

Rapid detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using saliva samples has emerged as a preferred technique since sample collection is easy and noninvasive. In addition, several commercial high-throughput PCR kits that do not require RNA extraction/purification have been developed and are now available for testing saliva samples. However, an optimal protocol for SARS-CoV-2 RT-PCR testing of saliva samples using the RNA extraction/purification-free kits has not yet been established. The aim of this study was to establish optimal preanalytical conditions, including saliva sample collection, storage, and dilution for RNA extraction/purification-free RT-PCR (direct RT-PCR). Patients suspected with COVID-19 from March 02 to August 31, 2020, were enrolled in this study. A total of 248 samples, including 43 nasopharyngeal swabs and 205 saliva samples, were collected from 66 patients (37 outpatients and 29 inpatients) and tested using the 2019 Novel Coronavirus Detection Kit (nCoV-DK, Shimadzu Corporation, Kyoto, Japan). The detection results obtained using nasopharyngeal swabs and saliva samples matched 100%. The sampling time, i.e., either awakening time or post-breakfast, had no significant effect on the viral load of the saliva samples. Although saliva samples are routinely diluted to reduce viscosity, we observed that dilution negatively affected PCR sensitivity. Saliva samples could be stored at room temperature (25°C) for 24 hours or at 4°C for up to 48 hours. This study demonstrated the appropriate conditions of saliva sample collection, processing, and storage, and indicated that the nCoV-DK is applicable to saliva samples, making the diagnosis method simple and safe.

Circulating tumor DNA is a prognostic marker of tumor recurrence in stage II and III colorectal cancer: multicentric, prospective cohort study (ALGECOLS)

BackgroundIn non-metastatic colorectal cancer (CRC), we evaluated prospectively the pertinence of longitudinal detection and quantification of circulating tumor DNA (ctDNA) as a prognostic marker of recurrence. MethodThe presence of ctDNA was assessed from plasma collected before and after surgery for 184 patients classified as stage II or III and at each visit during 3–4 years of follow-up. The ctDNA analysis was performed by droplet-based digital polymerase chain reaction, targeting mutation and methylation markers, blindly from the clinical outcomes. Multivariate analyses were adjusted on age, gender, stage, and adjuvant chemotherapy. ResultsBefore surgery, 27.5% of patients were positive for ctDNA detection. The rate of recurrence was 32.7% and 11.6% in patients with or without detectable ctDNA respectively (P = 0.001). Time to recurrence (TTR) was significantly shorter in patients with detectable ctDNA before (adjusted hazard ratio [HR] = 3.58, 95% confidence interval [CI] 1.71–7.47) or immediately after surgery (adjusted HR = 3.22, 95% CI 1.32–7.89). The TTR was significantly shorter in patients with detectable ctDNA during the early postoperative follow-up (1–6 months) (adjusted HR = 5, 95% CI 1.9–12.9). Beyond this period, ctDNA remained a prognostic marker with a median anticipated diagnosis of recurrence of 13.1 weeks (interquartile range 28 weeks) when compared to imaging follow-up. The rate of ctDNA+ might be underestimated knowing that consensus pre-analytical conditions were not described at initiation of the study. ConclusionThis prospective study confirms the relevance of ctDNA as a recurrence risk factor in stage II and III CRC before surgery and as a marker of minimal residual disease after surgery that may predict recurrence several months before imaging techniques.

Practical Details for the Detection and Interpretation of Cryoglobulins.

Cryoglobulins are immunoglobulins that precipitate at low temperature. Strict preanalytical and analytical conditions are critical for the detection of cryoglobulins. This review will focus on practical recommendations for detection and characterization of cryoglobulins and the technical problems that may be encountered. A laboratory report format is proposed for presentation of these results that includes the parameters necessary for an optimal interpretation by clinicians. The first step of detection of cryoglobulins can be performed in any laboratory that has a 37 °C incubator and temperature-controlled centrifuge. The second step is the characterization of cryoglobulins, and this often must be performed in more specialized laboratories. Characterization includes immunoglobulin typing, for the classification of cryoglobulins and potential underlying disease(s); quantification of immunoglobulins and rheumatoid factor in the cryoprecipitate to define the pathogenicity; and quantification of serum complement, which is useful for diagnosis. These practical recommendations will be useful for the accurate detection of cryoglobulins, an essential step for the diagnosis of cryoglobulinemic vasculitis, a rare but severe clinical manifestation of cryoglobulins.

Stability of lipids in plasma and serum: Effects of temperature-related storage conditions on the human lipidome

Large epidemiological studies often require sample transportation and storage, presenting unique considerations when applying advanced lipidomics techniques. The goal of this study was to acquire lipidomics data on plasma and serum samples stored at potential preanalytical conditions (e.g., thawing, extracting, evaporating), systematically monitoring lipid species for a period of one month. Split aliquots of 10 plasma samples and 10 serum samples from healthy individuals were kept in three temperature-related environments: refrigerator, laboratory benchtop, or heated incubator. Samples were analyzed at six different time points over 28 days using a Bligh & Dyer lipid extraction protocol followed by direct infusion into a lipidomics platform using differential mobility with tandem mass spectrometry. The observed concentration changes over time were evaluated relative to method and inter-individual biological variability. In addition, to evaluate the effect of lipase enzyme levels on concentration changes during storage, we compared corresponding fasting and post-prandial plasma samples collected from 5 individuals. Based on our data, a series of low abundance free fatty acid (FFA), diacylglycerol (DAG), and cholesteryl ester (CE) species were identified as potential analytical markers for degradation. These FFA and DAG species are typically produced by endogenous lipases from numerous triacylglycerols (TAGs), and certain high abundance phosphatidylcholines (PCs). The low concentration CEs, which appeared to increase several fold, were likely mass-isobars from oxidation of other high concentration CEs. Although the concentration changes of the high abundant TAG, PC, and CE precursors remained within method variability, the concentration trends of FFA, DAG, and oxidized CE products should be systematically monitored over time to inform analysts about possible pre-analytical biases due to degradation in the study sample sets.

Eosinophiluria: accreditation with establishment of an inter-laboratories exchange

Eosinophiluria corresponds to search eosinophils in urine. These are normally absent in urine, their presence could be associated with different clinical conditions affecting kidney or urinary tract. This analysis of medical biology laboratory listed in the French Nomenclature of acts of medical biology has to be validated according to norm NF EN ISO 15189. The principle of eosinophiluria method is based on eosinophils quantification by optical microscopy in a urine sample (urination) after staining. The aim of this article is to provide to biologists the eosinophiluria's clinical interest, but also bibliographic, technical and practical elements that can help them to establish eosinophiluria in their laboratories. The method validation elements were described for each item of SH Form 43. They include the analysis risks study, inter-operator variability, uncertainties, measurement range, comparison of methods based on the comparison of two staining, interferences, robustness, reliability of reagents, reference interval. Regarding accuracy, in absence of external quality assessment for this analysis, an inter-laboratory exchange has been set up in accordance with the requirements of the norm. Its organization is described. The performance of eosinophiluria was verified, recalling the importance of the pre-analytical conditions and the quality of staining. All of these data are presented and led the accreditation of eosinophiluria in our laboratory.

COMPARISON OF PROTHROMBIN TIME AND ACTIVATED PARTIAL THROMBOPLASTIN TIME IN PRIMARY TUBES AND SAMPLE ALIQUOTS AFTER 4 HOURS DURATION

Background: Coagulation tests are widely applied in clinical practice, among which PT and aPTT are the most commonly done. Among many preanalytical conditions –time, temperature and storage conditions are few of the factors affecting the results of samples. This study aims to compare PT and aPTT values in primary tubes and sample aliquots after 4 hours duration with the initial value. Materials & Methods : An observational study was done at Central Diagnostic Laboratory, Gandhi Hospital, Secunderabad, T.S. Samples were collected in citrated tubes, centrifuged, PT and aPTT were processed with plasma of primary tubes. Sufcient quantity of plasma was aliquoted immediately from primary tubes and kept at room temperature for 4 hours after which the plasma of primary tubes and aliquots were re-analyzed separately and values were compared. Results: Pearson correlation was performed to show the relation. PT and aPTT values obtained in the primary tube and aliquot were correlating with the initial value (PT-r =0.833,0.831 respectively) and (aPTT-r =0.97,0.87 respectively) and also with each other (PT-r =0.99) and (aPTT-r =0.90) respectively. There is no statistical signicant difference in PT of primary tube and aliquots when compared to initial PT (p>0.01). Incase of APTT there is statistically signicant difference in primary tube and aliquot when compared to initial value (p<0.01) where as there is no signicant difference of APTT values in aliquot and primary tube after 4 hours (p>0.01). Conclusion: The present study shows no difference of PT values in aliquots and primary tube when compared to initial value, whereas APTT values differ from initial values in samples stored for more than 4 hours in primary tube and aliquot.

Detection of Lung Cancer via Blood Plasma and 1H-NMR Metabolomics: Validation by a Semi-Targeted and Quantitative Approach Using a Protein-Binding Competitor.

Metabolite profiling of blood plasma, by proton nuclear magnetic resonance (1H-NMR) spectroscopy, offers great potential for early cancer diagnosis and unraveling disruptions in cancer metabolism. Despite the essential attempts to standardize pre-analytical and external conditions, such as pH or temperature, the donor-intrinsic plasma protein concentration is highly overlooked. However, this is of utmost importance, since several metabolites bind to these proteins, resulting in an underestimation of signal intensities. This paper describes a novel 1H-NMR approach to avoid metabolite binding by adding 4 mM trimethylsilyl-2,2,3,3-tetradeuteropropionic acid (TSP) as a strong binding competitor. In addition, it is demonstrated, for the first time, that maleic acid is a reliable internal standard to quantify the human plasma metabolites without the need for protein precipitation. Metabolite spiking is further used to identify the peaks of 62 plasma metabolites and to divide the 1H-NMR spectrum into 237 well-defined integration regions, representing these 62 metabolites. A supervised multivariate classification model, trained using the intensities of these integration regions (areas under the peaks), was able to differentiate between lung cancer patients and healthy controls in a large patient cohort (n = 160), with a specificity, sensitivity, and area under the curve of 93%, 85%, and 0.95, respectively. The robustness of the classification model is shown by validation in an independent patient cohort (n = 72).