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Objectives: To assess the appropriate preanalytical process for storage of plasma for renin concentration analysis. This study was initiated due to the wide variation in preanalytical handling of samples observed within our network, particularly with respect to freezing for longer term storage., Methods: Pooled plasma from patient samples was analysed immediately post separation for renin concentration (n=30, concentration 4.0-204 mIU/L). Aliquots from these samples were frozen in a -20 °C freezer and then analysed, with the renin concentration compared to the respective baseline concentration. Comparisons were also made to: aliquots snap frozen using a dry ice/acetone bath, aliquots stored at room temperature, and aliquots stored at 4 °C. Subsequent experiments investigated the potential sources of cryoactivation observed in these initial studies., Results: Substantial and highly variable cryoactivation was observed in samples frozen using a -20 °C freezer, with renin concentration increasing over 300% from baseline in some samples (median 21.3%). This cryoactivation could be prevented by snap freezing samples. Subsequent experiments determined that long term storage in a -20 °C freezer could prevent cryoactivation provided samples were initially frozen rapidly in a -70 °C freezer. Rapid defrosting of samples was not required to prevent cryoactivation., Conclusions: Standard -20 °C freezers may not be appropriate for freezing samples for renin analysis. Laboratories should consider snap freezing their samples using a -70 °C freezer or similar to avoid cryoactivation of renin., (© 2023 Walter de Gruyter GmbH, Berlin/Boston.)

Objectives: The aim of this study was to determine the appropriate transport and storage conditions for blood taken for direct renin concentration and plasma renin activity measurement, and whether cryoactivation of prorenin is seen at time points relevant to clinical practice., Methods: Blood was extracted from n=10 volunteers into K 2 -EDTA tubes. Stability of renin was assessed in whole blood stored at room temperature (15-25 °C) and in the refrigerator (2-8 °C) at 0 h, 8 h, and 24 h. The stability of renin in plasma was determined under the same conditions at 0 h, 24 h and 72 h., Results: Stability of plasma renin activity and direct renin concentration in whole blood stored at room temperature was found to be acceptable for up to 24 h. At refrigerated temperature, whole blood stability was acceptable for measurement of direct renin concentration up to 8 h and plasma renin activity up to 24 h. In contrast, plasma renin activity was not stable in plasma stored at either room or refrigerated temperatures up to 24 h; however, direct renin concentration had acceptable stability in plasma stored at room temperature for up to 24 h, but stability was unacceptable at refrigerated temperatures., Conclusions: Samples collected for plasma renin activity and direct renin concentration should be transported as whole blood to optimise stability. After sample processing, plasma can be kept at room temperature for up to 24 h for direct renin concentration, however, for determination of plasma renin activity separated plasma should be analysed or frozen as soon as possible., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

Inhibitor cystine knot (ICK) peptides are knotted peptides with three intramolecular disulfide bonds that affect several types of ion channels. Some are proteolytically stable and are promising scaffolds for drug development. GTx1-15 is an ICK peptide that inhibits the voltage-dependent calcium channel Ca v 3.1 and the voltage-dependent sodium channels Na v 1.3 and Na v 1.7. As a model molecule to develop an ICK peptide drug, we investigated several important pharmaceutical characteristics of GTx1-15. The stability of GTx1-15 in rat and human blood plasma was examined, and no GTx1-15 degradation was observed in either rat or human blood plasma for 24 h in vitro. GTx1-15 in blood circulation was detected for several hours after intravenous and intramuscular administration, indicating high stability in plasma. The thermal stability of GTx1-15 as examined by high thermal incubation and protein thermal shift assays indicated that GTx1-15 possesses high heat stability. The cytotoxicity and immunogenicity of GTx1-15 were examined using the human monocytic leukemia cell line THP-1. GTx1-15 showed no cytotoxicity or immunogenicity even at high concentrations. These results indicate that GTx1-15 itself is suitable for peptide drug development and as a peptide library scaffold.

Introduction: Haematology laboratories are increasingly faced with requests for add-on coagulation testing. This study explores extending the specimen storage proposals by examining coagulation parameters on refrigerated citrated plasma retained on a cellular fraction over a 24-hour period., Methods: Sodium citrate (Sarstedt ® S-Monovette 3.2%) specimens from 206 patients in University Hospital Limerick, Ireland were refrigerated immediately post-analysis and re-analysed in the centrifuged primary container at 4, 8 and 24-hour intervals using the Diagnostica Stago coagulometer and reagent combination. Coagulation assays examined for statistically and clinically significant differences included PT, APTT, D-Dimer, fibrinogen and Protein C., Results: PT, APTT and Protein C values displayed statistical significance from 4 hours. Fibrinogen differences were statistically significant from 8 hours. D-Dimer differences were not statistically significant at any interval over the 24-hour period. The refrigerated storage limit for PT and APTT results was determined to be 4 hours. D-Dimer was the only test parameter to report a mean percentage variance >10%. However, result changes at the threshold region of 0.5 µg/mL FEU were found to be within assay precision limits and desirable bias up to 8 hours. Maximum mean differences for Protein C (-1.3%) and fibrinogen (2.3%) were within assay precision limits and desirable biases up to 24 hours., Conclusion: PT and APTT results are stable in refrigerated citrated plasma maintained on a cellular fraction up to 4 hours post-phlebotomy. D-Dimers results are reliable up to 8 hours, while fibrinogen and Protein C results are stable for at least 24 hours., (© 2021 John Wiley & Sons Ltd.)

Measurement of metanephrines (MNs: metanephrine [MN] and normetanephrine [NMN]) is recommended for the initial biochemical diagnosis of pheochromocytoma and paraganglioma. Despite some drawbacks, plasma is commonly used for sampling. Here, we determined the feasibility of using serum, as an alternative to plasma, by comparing MNs in plasma and serum and evaluating the stability of MNs in serum. MNs obtained from serum, EDTA plasma, and heparin plasma were measured using LC-MS/MS immediately or after storage at 4 °C for 24 h, 72 h, and 7 days, and at -80 °C for 7 days, after sample collection. The differences between sample stability at given time points were compared using one-way ANOVA and Students' paired t -test, and the mean percent deviation was compared with total change limit (TCL). No significant difference was observed in MN and NMN between serum and EDTA plasma, and the mean percent deviation of the results obtained from serum compared to that from EDTA plasma was within the TCL. However, the difference of MN between EDTA plasma and heparin plasma exceeded the TCL. Both MNs in EDTA plasma and heparin plasma showed a significant decreasing trend at 4 °C with time ( p  < .01), while those in serum were relatively stable, with the mean percent deviation not exceeding the TCL at any time point or temperature. In conclusion, MNs measurement did not significantly differ between EDTA plasma and serum when measured immediately after collection, and MNs in serum were more stable than that in plasma.

Background: This prospective study evaluated the effect of routine, uncontrolled, Israeli field storage conditions on the safety and efficacy of Lyo-Plas N Freeze-Dried Plasma (FDP) at the end of the manufacturer's shelf life, and up to 24 months post expiry. Clotting factors V, VIII and XI, proteins S, C, fibrinogen, PTT, ATIII, VWF, and INR as well as TEG, DDM, residual moisture, pH, and sterility of FDP returned from field units after uncontrolled storage were evaluated., Study Design and Methods: Parameters measured at the end of manufacturer shelf life, as well as 6, 12, 18, and 24 months after expiry, were compared to those of freshly supplied FDP doses., Results: Changes were found when comparing freshly supplied FDP to all field-stored groups in INR, PT, PTT, pH, fibrinogen, and factor VIII. A significant change was also seen in Factor XI in the 12, 18, and 24 months post-expiry samples, Factor V and R in the 24 months post-expiry samples, MA in the 12, 24 months post-expiry group, and Protein C in the 18 months post-expiry group. An increase in the residual moisture from 0.90% in freshly supplied FDP to 1.35% in 24 months post-expiry FDP.; all p < .05. No growth was found in sterility analysis., Conclusion: Despite uncontrolled field storage conditions, the findings demonstrate that the safety and efficacy of FDP units, stored in uncontrolled conditions are only slightly affected, even beyond their expiration date. This information allows consideration of possibly extending the shelf life., (© 2021 AABB.)

Protein biomarker microheterogeneity has attracted increasing attention in epidemiological and clinical research studies. Knowledge concerning the preanalytical stability of proteins is paramount to assess the biological significance of their proteoforms. We investigated the stability of the inflammatory markers C-reactive protein (CRP), serum amyloid A (SAA), and calprotectin (S100A8/9), and the renal function marker, cystatin C (CnC). In total 16 proteoforms were quantified by immuno-MALDI-TOF MS in EDTA plasma and serum samples from 15 healthy volunteers. Prior to analysis blood samples were stored at either room temperature from 1 h up to 8 days, or underwent up to 9 consecutive freeze/thaw cycles. Pearson's correlation coefficient and t-test, intra-class correlation coefficient (ICC), and Autoregressive Integrated Moving-Average (ARIMA) models were used to investigate the stability of proteoform concentrations and distributions in blood. Plasma and serum concentrations of CRP and SAA proteoforms were highly stable during room temperature exposure and repeated freeze/thaw cycles, demonstrating excellent reproducibility (ICC > 0.75), no serial dependency in ARIMA models, and stable distribution of proteoforms. Stability analyses for proteoforms of S100A8/9 and CnC identified only minor preanalytical changes in concentrations and distributions, and none of the proteoforms were produced during prolonged exposure to room temperature or repeated freezing/thawing. The four proteins and their proteoforms are stable during sub-optimal sample handling, and represent robust biomarker candidates for future biobank studies aimed at investigating the microheterogeneity of SAA, S100A8/9, and CnC in relation to inflammation, renal dysfunction and various clinical outcomes., (Copyright © 2020 The Author(s). Published by Elsevier B.V. All rights reserved.)

Vitamin C is a necessary micronutrient that is involved in many biological processes. In preserved human plasma and serum, vitamin C is most meaningfully analyzed as total ascorbic acid (TAA). From 1993 through 2015, the National Institute of Standards and Technology (NIST) coordinated 40 interlaboratory studies (ILS) devoted to improving the between-participant comparability of TAA measurements. The results from these ILS demonstrate that the concentration of TAA ([TAA]) is stable for at least 20 years in serum diluted 1 + 1 (volume fraction) with 10% mass concentration aqueous metaphosphoric acid (MPA) and stored at -80 °C. The between-participant relative reproducibility precision, expressed as a coefficient of variation (CV), improved from over 16% to under 9% over the course of the studies. Normalization of test samples (i.e., ex post-facto recalibrating the as-submitted results) using participant-prepared serum-free calibration solutions did not improve reproducibility. Normalization to one control sample having a similar serum-based matrix as the test samples improved the CV to 7%; normalization to two such controls reduced the CV to 4%. Multicenter studies that require the highest degree of measurement comparability among the participants should consider calibrating with materials that have a serum-based matrix as similar as possible to that of the samples of interest.

Background: Adrenocorticotropic hormone (ACTH) has been reported to be labile in blood due to proteolytic degradation and stringent procedures are followed to prevent in vitro degradation after sample collection., Objective: The purpose of this study was to examine the effect of time and temperature before and after separation of plasma from cells in the quantitation of plasma ACTH., Methods: Our current protocol includes sample collection in a pre-chilled tube, transport on ice and immediate centrifugation at 4 °C. These reference conditions were compared against sample processing in tubes and centrifuge set at room-temperature; using delayed centrifugation at 4 °C. ACTH stability was evaluated at ambient and refrigerated temperatures after collection and plasma separation using the reference protocol. Plasma samples were analyzed using the Roche Elecsys ACTH immunoassay., Results: Quantification of ACTH was not impacted by the use of non-chilled tubes and centrifuge and up to a 4 h delay in separation of plasma from cells. Average percent differences in plasma ACTH concentration from time 0 was <10% up to 12 h at ambient temperature. Refrigeration of plasma did not preserve ACTH stability at 12 h and longer storage resulted in significant ACTH degradation at both ambient and refrigerated temperatures., Conclusions: As supported by these data, previously recommended strict specimen collection and processing requirements are not necessary for measuring ACTH with the Roche Elecsys immunoassay., (Copyright © 2020 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Natriuretic peptides are a laboratory tool with significant implications for the diagnosis and prognosis of heart failure (HF). The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) recommended that assays must be examined for sample stability because there appears to be assay dependent. We aimed to evaluate the in vitro stability of B-type natriuretic peptide (BNP) under different handling conditions and using a BNP assay from Fujirebio Diagnostics (Tokyo, Japan). BNP concentrations were measured in plasma EDTA samples from 11 subjects to evaluate the in vitro stability at room temperature and at 4 °C and in 10 subjects to check the in vitro stability of samples stored at -20 °C during 1 and 3 months. Stability limit was defined according to Spanish Society of Laboratory Medicine (SEQC-ML) recommendations. At room temperature and 4 °C, BNP concentrations decreased progressively in samples collected in both groups, remaining stable within four hours from collection. BNP concentrations also were stable within four hours from collection in whole blood at room temperature. Finally, at -20 °C, BNP concentrations remained stable in both groups at 1 and 3 months, respectively. According to our results, BNP, stored at room temperature or at 4 °C, should be assayed in the first four hours after collection. Besides, BNP was shown to be stable in whole blood for at least four hours at room temperature. If the testing cannot be performed within the first four hours, the plasma should be frozen and kept at -20 °C for up to 3 months.

Objective: This study aimed to determine the precision dose of Chinese universal pooled plasma (CUPP) developed by our laboratory, and the stability of plasma proteins and factors., Methods: A total of 100 single fresh-frozen plasma (FFP) units were selected to test plasma proteins, including total protein, albumin, fibrinogen, factor V, factor VIII, antithrombin-III, and protein C. Different pooling protocols with 20, 40, 60, 80, and 100 units were used to optimize the number of pooled units. The pooled plasma was then used to further evaluate the optimal storage conditions and duration at 22°C, 4°C, and -20°C., Results: There were considerable differences in plasma protein levels among single units of FFP. After different pooling protocols, the mean value of plasma proteins did not significantly change. However, with a larger number of pooled samples, plasma proteins were more stable with a smaller standard deviation. Acceptable storage for CUPP was achieved with storage for 1 day at 22°C, 4 days at 4°C, and 3 months at -20°C., Conclusion: A uniform level of plasma proteins and factors in CUPP appears to support establishment of a precise dose of plasma.

Objective: We wished to re-assess the relative stability of microRNAs (miRNAs) as compared with other RNA molecules, which has been confirmed in many contexts. When bound to Argonaute proteins, miRNAs are protected from degradation, even when released into the extracellular space in ribonucleoprotein complexes, and with or without the protection of membranes in extracellular vesicles. Purified miRNAs also appear to present less of a target for degradation than other RNAs. Although miRNAs are by no means immune to degradation, biological samples subjected to prolonged incubation at room temperature, multiple freeze/thaws, or collection in the presence of inhibitors like heparin, can typically be remediated or used directly for miRNA measurements., Results: Here, we provide additional confirmation of early, well validated findings on miRNA stability and detectability. Our data also suggest that inadequate depletion of platelets from plasma may explain the occasional report that freeze-thaw cycles can adversely affect plasma miRNA levels. Overall, the repeated observation of miRNA stability is again confirmed.

In the present study, a sensitive and robust LC-MS/MS method has been developed and validated for the quantification of riluzole in human plasma and cerebrospinal fluid (CSF) in clinical samples from patients with spinal cord injury (SCI). Riluzole and its labeled internal standard (IS) were isolated from plasma and CSF by liquid-liquid extraction using ethyl acetate. Riluzole (m/z 235→166) and IS (m/z 238→169) were detected by electrospray ionization (ESI) using multiple reaction monitoring (MRM) in a positive mode. The assay was linear in the concentration range of 0.5 (LLOQ, signal/noise ratio>10)-800ng/ml in plasma, and 1.0 (LLOQ)-800ng/ml in CSF samples. The intra- and inter-day accuracy in plasma were 94.2-110.0% and 97.8-102.0%, respectively, and those in CSF were 87.6-105.1% and 91.9-98.8%, respectively. The intra- and inter-day precision were 2.2-7.2% and 4.0-9.1%, respectively, in plasma, and 1.4-14.1% and 2.6-11.5%, respectively in CSF. Matrix effect was negligible from both matrices with signal percentages of 97.6-100.6% in plasma and 99.4-106.4% in CSF. The recoveries were >75% in plasma, >84% in CSF with low protein (53.9mg/dl), and >68% in CSF with high protein (348.2mg/dl). This method was successfully applied to quantify riluzole concentrations in plasma and CSF from patients with SCI., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Osmolality reflects the concentration of all dissolved particles in a body fluid, and its measurement is routinely performed in clinical laboratories for the differential diagnosis of disorders related with the hydrolytic balance regulation, the renal function and in small-molecule poisonings. The aim of the study was to assess the stability of serum, plasma and urine osmolality through time and under different common storage conditions, including delayed centrifugation., Methods: Blood and urine samples were collected, and classified into different groups according to several preanalytical variables: serum or plasma lithium-heparin tubes; spun or unspun; stored at room temperature (RT), at 4°C or frozen at -21°C. Aliquots from each group were assayed over time, for up to 14days. Statistical differences were based on three different international performance criteria., Results: Whole blood stability was higher in the presence of anticoagulant. Serum osmolality was stable for 2days at RT and 8days at 4°C, while plasma was less stable when refrigerated. Urine stability was 5days at RT, 4days at 4°C and >14days when frozen., Discussion: Osmolality may be of great interest for the management of several conditions, such as in case of a delay in the clinical suspicion, or in case of problems in sample collection or processing. The ability to obtain reliable results for samples kept up to 14days also offers the possibility to retrospectively assess baseline values for patients which may require it., (Copyright © 2017. Published by Elsevier Inc.)

Brain-derived neurotrophic factor (BDNF), an important neural growth factor, has gained growing interest in neuroscience, but many influencing physiological and analytical aspects still remain unclear. In this study we assessed the impact of storage time at room temperature, repeated freeze/thaw cycles, and storage at -80 °C up to 6 months on serum and ethylenediaminetetraacetic acid (EDTA)-plasma BDNF. Furthermore, we assessed correlations of serum and plasma BDNF concentrations in two independent sets of samples. Coefficients of variations (CVs) for serum BDNF concentrations were significantly lower than CVs of plasma concentrations ( n = 245, p = 0.006). Mean serum and plasma concentrations at all analyzed time points remained within the acceptable change limit of the inter-assay precision as declared by the manufacturer. Serum and plasma BDNF concentrations correlated positively in both sets of samples and at all analyzed time points of the stability assessment ( r = 0.455 to r s < 0.004). In summary, when considering the acceptable change limit, BDNF was stable in serum and in EDTA-plasma up to 6 months. Due to a higher reliability, we suggest favoring serum over EDTA-plasma for future experiments assessing peripheral BDNF concentrations.p < 0.004). In summary, when considering the acceptable change limit, BDNF was stable in serum and in EDTA-plasma up to 6 months. Due to a higher reliability, we suggest favoring serum over EDTA-plasma for future experiments assessing peripheral BDNF concentrations., Competing Interests: The authors declare no conflict of interest.

Carboplatin is a chemotherapy drug used in a variety of cancers with the primary toxicity being exposure-dependant myelosuppression. We present the development and validation of a simple, robust inductively coupled plasma mass spectrometry (ICP-MS) method to measure carboplatin in plasma ultrafiltrate. Plasma ultrafiltrates samples were prepared using Amicon Ultra 30,000da cut-off filters and then diluted with ammonia EDTA before ICP-MS analysis. The assay was validated in the range 0.19-47.5mg/L carboplatin in ultrafiltrate. The assay was linear (r 2 >0.9999), accurate (<6% bias, 12% bias at LLOQ) and precise (intra- and inter-day precision of <3% coefficient of variation). No matrix effects were observed between plasma ultrafiltrate and aqueous platinum calibrators and recovery was complete. The assay was applied to 10 clinical samples from patients receiving carboplatin. Incurred sample reanalysis showed reproducible values over 3 analysis days (<6% CV). As plasma stability prior to ultrafiltration has been a major concern in previous clinical studies this was studied extensively at room temperature (22°C) over 24h. Carboplatin was found to be stable in both spiked plasma (n=3) and real patient samples (n=10) at room temperature for up to 8h before ultrafiltration. This makes routine measurement of carboplatin concentrations in clinical settings feasible., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Blood microRNAs (miRNAs) are ideal biomarkers, and blood derivatives are often collected in the scope of miRNA research projects. However, knowledge of temporal variations of miRNAs in healthy individuals is lacking. In this study, miRNA variability was measured over a 1-year period in different blood derivatives, collected every 2-3 months from two healthy donors. There is a continuum of intraindividual temporal variability, with particularly stable (coefficient of variation [CV] <20%-30%) and particularly unstable (CV >100%-130%) miRNAs in serum, plasma, and specific white blood cell subpopulations. The temporal intraindividual variability of miRNAs should be taken into consideration in experimental design of biospecimen collections and validation of diagnostic biomarkers.

Background: The stability of biochemical analytes has already been investigated, but results strongly differ depending on parameters, methodologies, and sample storage times. We investigated the stability for many biochemical parameters after different storage times of both whole blood and plasma, in order to define acceptable pre- and postcentrifugation delays in hospital laboratories., Methods: Twenty-four analytes were measured (Modular® Roche analyzer) in plasma obtained from blood collected into lithium heparin gel tubes, after 2-6 hr of storage at room temperature either before (n = 28: stability in whole blood) or after (n = 21: stability in plasma) centrifugation. Variations in concentrations were expressed as mean bias from baseline, using the analytical change limit (ACL%) or the reference change value (RCV%) as acceptance limit., Results: In tubes stored before centrifugation, mean plasma concentrations significantly decreased after 3 hr for phosphorus (-6.1% [95% CI: -7.4 to -4.7%]; ACL 4.62%) and lactate dehydrogenase (LDH; -5.7% [95% CI: -7.4 to -4.1%]; ACL 5.17%), and slightly decreased after 6 hr for potassium (-2.9% [95% CI: -5.3 to -0.5%]; ACL 4.13%). In plasma stored after centrifugation, mean concentrations decreased after 6 hr for bicarbonates (-19.7% [95% CI: -22.9 to -16.5%]; ACL 15.4%), and moderately increased after 4 hr for LDH (+6.0% [95% CI: +4.3 to +7.6%]; ACL 5.17%). Based on RCV, all the analytes can be considered stable up to 6 hr, whether before or after centrifugation., Conclusion: This study proposes acceptable delays for most biochemical tests on lithium heparin gel tubes arriving at the laboratory or needing to be reanalyzed., (© 2016 Wiley Periodicals, Inc.)

A polystyrene surface (PS) was initially treated by cold nitrogen and oxygen plasma in order to incorporate in particular amine and hydroxyl functions, respectively. The evolution of the chemical nature of the surface was further monitored over a long time period (580 days) by chemical assay, XPS and contact angle measurements. Surface density quantification of primary amine groups was performed using three chemical amine assays: 4-nitrobenzaldehyde (4-NBZ), Sulfo succinimidyl 6-[3'(2 pyridyldithio)-pionamido] hexanoate (Sulfo-LC-SPDP) and iminothiolane (ITL). The results showed amine densities were in the range of 2 per square nanometer (comparable to the results described in the literature) after 5min of nitrogen plasma treatment. Over the time period investigated, chemical assays, XPS and contact angles suggest a drastic significant evolution of the chemical nature of the surface within the first two weeks. Beyond that time period and up to almost two years, nitrogen plasma modified substrates exhibits a slow and continuous oxidation whereas oxygen plasma modifed polystyrene surface is chemically stable after two weeks of storage. The latter appeared to "ease of" showing relatively mild changes within the one year period. Our results suggest that it may be preferable to wait for a chemical "stabilization" period of two weeks before subsequent covalent immobilization of proteins onto the surface. The originality of this work resides in the study of the plasma treated surface chemistry evolution over long periods of storage time (580 days) considerably exceeding those described in the literature., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Biomarkers such as cytokines, chemokines, and soluble activation markers can be unstable when processing of blood is delayed. The stability of various biomarkers in serum and plasma was investigated when unprocessed blood samples were stored for up to 24h at room and refrigerator temperature., Methods: Blood was collected from 16 healthy volunteers. Unprocessed serum, EDTA and heparinized blood was stored at room (20-25°C) and refrigerator temperature (4-8°C) for 0.5, 2, 4, 6, 8, and 24h after collection before centrifugation and separation of serum and plasma. Samples were batch tested for various biomarkers using commercially available immunoassays. Statistically significant changes were determined using the generalized estimating equation., Results: IFN-γ, sIL-2Rα, sTNF-RII and β2-microglobulin were stable in unprocessed serum, EDTA and heparinized blood samples stored at either room or refrigerator temperature for up to 24h. IL-6, TNF-α, MIP-1β and RANTES were unstable in heparinized blood at room temperature; TNF-α, and MIP-1β were unstable in unprocessed serum at room temperature; IL-12 was unstable in unprocessed serum at refrigerator temperature; and neopterin was unstable in unprocessed EDTA blood at room temperature. IL-1ra was stable only in unprocessed serum at room temperature., Conclusion: All the biomarkers studied, with the exception of IL-1ra, were stable in unprocessed EDTA blood stored at refrigerator temperature for 24h. This indicates that blood for these biomarkers should be collected in EDTA and if delays in processing are anticipated the unseparated blood should be stored at refrigerator temperature until processing., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Quantitative real-time PCR (QRT-PCR) assays are faster, more precise, and more sensitive quantitative laboratory methods for monitoring serial CMV DNA viral load in patients undergoing organ or hematopoietic stem cell transplantation. Clinical laboratories often face practical concerns about the storage of specimens from these patients to ensure the accuracy and reproducibility of CMV viral load test results. Different studies that have assessed CMV DNA stability have shown mixed results. Therefore, we analyzed CMV DNA stability of 30 EDTA plasma samples in samples containing between 300 and 100,000copies/ml over a 21 day period. The concentration of CMV DNA in all samples stored at 4°C for 21 days did not differ significantly from the baseline viral load (t=0.242, p=0.810), and no trend was evident to indicate continued degradation over a 2 week period., (Copyright © 2014. Published by Elsevier B.V.)

7-O-Succinyl macrolactin A (SMA) and its major metabolite macrolactin A (MA) are generated from Bacillus polyfermenticus KJS-2. Both substances show inhibitory effects on angiogenesis and cancer cell invasion. SMA in rat plasma is known to be relatively stable at room temperature, but MA was not detected due to its instability. Therefore, a stabilizer is required to accurately measure the substance in biological rat samples. In this study, NaF and eserine were examined to determine whether they could stabilize MA to allow for accurate measurement in rat plasma. We also developed a rapid and simple chromatographic method using tandem mass spectrometry (MS/MS) for the simultaneous determination of these compounds in rat plasma. After simple protein precipitation with acetonitrile including methaqualone (internal standard), the analytes were chromatographed on a Hilic column with a mobile phase of 10mM formic acid aqueous solution, methanol, and acetonitrile (15:15:70, v/v). The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. This analytical method was successfully applied to monitor plasma concentrations of both compounds over time following intravenous administration of a salt form of SMA in rats., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Silver nanowires (AgNW) find use in transparent conductive electrodes with applications in solar cells, touch screens, and wearables. Unprotected AgNW are prone to atmospheric corrosion and lose conductivity over time. Known passivation techniques either require submersion of pre‐deposited AgNW in liquid compounds or the modification of AgNW inks prior to deposition, which alters viscosity and complicates deposition. Here, new possibilities for stabilization of pre‐deposited AgNW networks without need for submersion are explored. It is demonstrated that AgNW networks can be stabilized either by argon or hydrogen plasma treatment or by solvent vapor annealing with ethanol, methanol, or ethyl acetate. These treatments yielded stable electrical resistance over at least nine weeks, whereas untreated or thermally annealed AgNW layers quickly lost conductivity. The potential of solvent vapor annealing is further explored by demonstrating a new processing technique for stable polymer matrix composites containing AgNW. Co‐deposited layers of AgNW with polystyrene microbeads are annealed in ethyl acetate vapor to stabilize the AgNW while at the same time merging polymer beads into a closed film around the AgNW. The resulting composites maintained stable resistance and transmittance for at least seven weeks. [ABSTRACT FROM AUTHOR]

The stability of antibiotic preanalytical samples is a critical factor in therapeutic drug monitoring (TDM), a practice of undoubted importance for the proper therapeutic use of antibiotics, especially in complex management patients, such as pediatrics. This review aims to analyze the data in the literature regarding the preanalytical stability of some of the antibiotics for which TDM is most frequently requested. The literature regarding the preanalytical stability of amikacin, ampicillin, cefepime, ceftazidime, ciprofloxacin, daptomycin, gentamicin, levofloxacin, linezolid, meropenem, piperacillin, teicoplanin, and vancomycin in plasma, serum, whole blood, and dried blood/plasma spot samples was analyzed. Various storage temperatures (room temperature, 4 °C, −20 °C, and −80 °C) and various storage times (from 1 h up to 12 months) as well as subjecting to multiple freeze–thaw cycles were considered. The collected data showed that the non-beta-lactam antibiotics analyzed were generally stable under the normal storage conditions used in analytical laboratories. Beta-lactam antibiotics have more pronounced instability, particularly meropenem, piperacillin, cefepime, and ceftazidime. For this class of antibiotics, we suggest that storage at room temperature should be limited to a maximum of 4 h, storage at 2–8 °C should be limited to a maximum of 24 h, and storage at −20 °C should be limited to a maximum of 7 days; while, for longer storage, freezing at −80 °C is suggested. [ABSTRACT FROM AUTHOR]

Background: Tests for hemostasis include prothrombin time (PT) and activated thromboplastin time (aPTT). Prothrombin time (PT) and activated partial thromboplastin time (APTT) are tests of hemostasis employed in the evaluation of coagulopathies and monitoring of anticoagulant drug therapy. These tests are supposed to be influences by many preanalytical factors. Objective: In this study, we have evaluated the stability of aliquoted plasma of blood sample collected in sodium citrate tubes for prothrombin time and activated partial thromboplastin time stored at -20°C for a period of 7 days. Material and Methods: 67 Patients samples collected for PT and APTT were stored for 7 days at -20°C in different aliquots. One aliquot is taken out daily and tested for PT and aPTT. Results were compared with initial tests results. Results: It was found that there was no significant difference between initial test results and test results of the samples are stored at -20°C. Conclusion: Samples which are collected for coagulation studies in sodium citrate preservative, if are centrifuged immediately and plasma is stored at -20°C, result generated for PT and aPTT do not show any statistically significant difference compared to samples which are immediately processed. [ABSTRACT FROM AUTHOR]

The JT-60SA device offers unique conditions before ITER for the study of the interaction of energetic particles with plasma waves. With similar dimensions to JET, e.g., a major radius but with a slightly more elongated plasma volume, JT- 60SA is used as a high-power device where additional heating power (including 10 MW of the 500 keV Neutral Beam Injection) of up to 41 MW and the potential for high non-inductive plasma current operation pave the path for numerous challenges in physics on MHD stability, in particular, when considering the effects of energetic particles. Several operational scenarios with ITER and DEMO-relevant plasma regimes, in terms of non-dimensional plasma parameters, are anticipated. In this work, the stability of Alfvén eigenmodes (AEs) in variants of two of the most relevant operational scenarios with single null is analyzed: a full Ip inductive scenario at high density (1.1 × 1020 m-3 on-axis electron density) and 5.48MA/2.05T toroidal plasma current and magnetic field, and an advanced (hybrid) scenario with an ion energy transport barrier (ITB) and 3.5MA/2.28T toroidal plasma current and magnetic field. The workflow included the CRONOS code to establish the scenario, the ASCOT code to calculate the slowing-down energetic particle distributions for a positive/negative ion source-based neutral beam, and the MISHKA/CASTOR-K suite to calculate the MHD spectra of AEs and the associated drive/damping contributions from the NBI energetic ions, as well as the thermal ion landau damping. The systematic analysis, over a large Fourier space of the toroidal mode number/mode frequency, provides evidence that although a significant fraction of supra-Alfvénic particles stemming from the negative ion source-based neutral beam (500 keV) can, in some cases, drive to AEs in both scenarios, it is not enough to overcome the thermal ion landau damping. In addition, the advanced scenario with ITB is shown to be stable against AEs localized in the vicinity of the barrier as well, offering good prospects of sustainability of the plasma performance and of ITB. Finally, some sensitivity scan results are shown on the influence of fast ion density and q-profile on the AE mode spectra and stability. [ABSTRACT FROM AUTHOR]

The stability of antibiotic preanalytical samples is a critical factor in therapeutic drug monitoring (TDM), a practice of undoubted importance for the proper therapeutic use of antibiotics, especially in complex management patients, such as pediatrics. This review aims to analyze the data in the literature regarding the preanalytical stability of some of the antibiotics for which TDM is most frequently requested. The literature regarding the preanalytical stability of amikacin, ampicillin, cefepime, ceftazidime, ciprofloxacin, daptomycin, gentamicin, levofloxacin, linezolid, meropenem, piperacillin, teicoplanin, and vancomycin in plasma, serum, whole blood, and dried blood/plasma spot samples was analyzed. Various storage temperatures (room temperature, 4 °C, −20 °C, and −80 °C) and various storage times (from 1 h up to 12 months) as well as subjecting to multiple freeze–thaw cycles were considered. The collected data showed that the non-beta-lactam antibiotics analyzed were generally stable under the normal storage conditions used in analytical laboratories. Beta-lactam antibiotics have more pronounced instability, particularly meropenem, piperacillin, cefepime, and ceftazidime. For this class of antibiotics, we suggest that storage at room temperature should be limited to a maximum of 4 h, storage at 2–8 °C should be limited to a maximum of 24 h, and storage at −20 °C should be limited to a maximum of 7 days; while, for longer storage, freezing at −80 °C is suggested.

The JT-60SA device offers unique conditions before ITER for the study of the interaction of energetic particles with plasma waves. With similar dimensions to JET, e.g., a major radius but with a slightly more elongated plasma volume, JT-60SA is used as a high-power device where additional heating power (including 10 MW of the 500 keV Neutral Beam Injection) of up to 41 MW and the potential for high non-inductive plasma current operation pave the path for numerous challenges in physics on MHD stability, in particular, when considering the effects of energetic particles. Several operational scenarios with ITER and DEMO-relevant plasma regimes, in terms of non-dimensional plasma parameters, are anticipated. In this work, the stability of Alfvén eigenmodes (AEs) in variants of two of the most relevant operational scenarios with single null is analyzed: a full Ip inductive scenario at high density (1.1 × 1020 m−3 on-axis electron density) and 5.48MA/2.05T toroidal plasma current and magnetic field, and an advanced (hybrid) scenario with an ion energy transport barrier (ITB) and 3.5MA/2.28T toroidal plasma current and magnetic field. The workflow included the CRONOS code to establish the scenario, the ASCOT code to calculate the slowing-down energetic particle distributions for a positive/negative ion source-based neutral beam, and the MISHKA/CASTOR-K suite to calculate the MHD spectra of AEs and the associated drive/damping contributions from the NBI energetic ions, as well as the thermal ion landau damping. The systematic analysis, over a large Fourier space of the toroidal mode number/mode frequency, provides evidence that although a significant fraction of supra-Alfvénic particles stemming from the negative ion source-based neutral beam (500 keV) can, in some cases, drive to AEs in both scenarios, it is not enough to overcome the thermal ion landau damping. In addition, the advanced scenario with ITB is shown to be stable against AEs localized in the vicinity of the barrier as well, offering good prospects of sustainability of the plasma performance and of ITB. Finally, some sensitivity scan results are shown on the influence of fast ion density and q-profile on the AE mode spectra and stability.

The anti-Müllerian hormone (AMH) is a glycoprotein that plays an important role in prenatal sex differentiation. It is used as a biomarker in polycystic ovary syndrome (PCOS) diagnostics, as well as for estimating an individual's ovarian reserve and the ovarian response to hormonal stimulation during in vitro fertilization (IVF). The aim of this study was to test the stability of AMH during various preanalytical conditions that are in accordance with the ISBER (International Society for Biological and Environmental Repositories) protocol. Plasma and serum samples were taken from each of the 26 participants. The samples were then processed according to the ISBER protocol. AMH levels were measured in all the samples simultaneously using the chemiluminescent kit ACCESS AMH in a UniCel® DxI 800 Immunoassay System (Beckman Coulter, Brea, CA, USA). The study proved that AMH retains a relatively high degree of stability during repeated freezing and thawing in serum. AMH was shown to be less stable in plasma samples. Room temperature proved to be the least suitable condition for the storage of samples before performing the biomarker analysis. During the testing of storage stability at 5–7 °C, the values decreased over time for all the plasma samples but remained stable in the serum samples. We proved that AMH is highly stable under various stress conditions. The anti-Müllerian hormone retained the greatest stability in the serum samples. [ABSTRACT FROM AUTHOR]

BACKGROUND: Oxidized derivatives of polyunsaturated fatty acids, collectively known as oxylipins, are labile bioactive mediators with diverse roles in human physiology and pathology. Oxylipins are increasingly being measured in plasma collected in clinical studies to investigate biological mechanisms and as pharmacodynamic biomarkers for nutrient-based and drug-based interventions. Whole blood is generally stored either on ice or at room temperature prior to processing. However, the potential impacts of delays in processing, and of temperature prior to processing, on oxylipin concentrations are incompletely understood. OBJECTIVE: To evaluate the effects of delayed processing of blood samples in a timeframe that is typical of a clinical laboratory setting, using typical storage temperatures, on concentrations of representative unesterified oxylipins measured by liquid chromatography-tandem mass spectrometry. DESIGN: Whole blood (drawn on three separate occasions from a single person) was collected into 5 mL purple-top potassium-EDTA tubes and stored for 0, 10, 20, 30, 60 or 120 min at room temperature or on wet ice, followed by centrifugation at 4 °C for 10 min with plasma collection. Each sample was run in duplicate, therefore there were six tubes and up to six data points at each time point for each oxylipin at each condition (ice/room temperature). Representative oxylipins derived from arachidonic acid, docosahexaenoic acid, and linoleic acid were quantified by liquid chromatography tandem mass spectrometry. Longitudinal models were used to estimate differences between temperature groups 2 h after blood draw. RESULTS: We found that most oxylipins measured in human plasma in traditional potassium-EDTA tubes are reasonably stable when stored on ice for up to 2 h prior to processing, with little evidence of auto-oxidation in either condition. By contrast, in whole blood stored at room temperature, substantial time-dependent increases in the 12-lipoxygenase-derived (12-HETE, 14-HDHA) and platelet-derived (thromboxane B2) oxylipins were observed. CONCLUSION: These findings suggest that certain plasma oxylipins can be measured with reasonable accuracy despite delayed processing for up to 2 h when blood is stored on ice prior to centrifugation. 12-Lipoxygenase- and platelet-derived oxylipins may be particularly sensitive to post-collection artifact with delayed processing at room temperature. Future studies are needed to determine impacts of duration and temperature of centrifugation on oxylipin concentrations.

BackgroundOxidized derivatives of polyunsaturated fatty acids, collectively known as oxylipins, are labile bioactive mediators with diverse roles in human physiology and pathology. Oxylipins are increasingly being measured in plasma collected in clinical studies to investigate biological mechanisms and as pharmacodynamic biomarkers for nutrient-based and drug-based interventions. Whole blood is generally stored either on ice or at room temperature prior to processing. However, the potential impacts of delays in processing, and of temperature prior to processing, on oxylipin concentrations are incompletely understood.ObjectiveTo evaluate the effects of delayed processing of blood samples in a timeframe that is typical of a clinical laboratory setting, using typical storage temperatures, on concentrations of representative unesterified oxylipins measured by liquid chromatography-tandem mass spectrometry.DesignWhole blood (drawn on three separate occasions from a single person) was collected into 5 mL purple-top potassium-EDTA tubes and stored for 0, 10, 20, 30, 60 or 120 min at room temperature or on wet ice, followed by centrifugation at 4 °C for 10 min with plasma collection. Each sample was run in duplicate, therefore there were six tubes and up to six data points at each time point for each oxylipin at each condition (ice/room temperature). Representative oxylipins derived from arachidonic acid, docosahexaenoic acid, and linoleic acid were quantified by liquid chromatography tandem mass spectrometry. Longitudinal models were used to estimate differences between temperature groups 2 h after blood draw.ResultsWe found that most oxylipins measured in human plasma in traditional potassium-EDTA tubes are reasonably stable when stored on ice for up to 2 h prior to processing, with little evidence of auto-oxidation in either condition. By contrast, in whole blood stored at room temperature, substantial time-dependent increases in the 12-lipoxygenase-derived (12-HETE, 14-HDHA) and platelet-derived (thromboxane B2) oxylipins were observed.ConclusionThese findings suggest that certain plasma oxylipins can be measured with reasonable accuracy despite delayed processing for up to 2 h when blood is stored on ice prior to centrifugation. 12-Lipoxygenase- and platelet-derived oxylipins may be particularly sensitive to post-collection artifact with delayed processing at room temperature. Future studies are needed to determine impacts of duration and temperature of centrifugation on oxylipin concentrations.

The use and abuse of cannabis, be it for medicinal or recreational purposes, is widely spread among the population. Consequently, a market for more potent and consequently more toxic synthetic cannabinoids has flourished, and with it, the need for accurate testing of these substances in intoxicated people. In this regard, one of the critical factors in forensic toxicology is the stability of these drugs in different biological matrices due to different storage conditions. This review aims to present the most updated and relevant literature of studies performed on the effects of different storage conditions on the stability of cannabis compounds present in various biological matrices, such as blood and plasma, urine, and oral fluids, as well as in alternative matrices, such as breath, bile fluid, hair, sweat, cerumen, and dried blood spots. [ABSTRACT FROM AUTHOR]

The anti-Müllerian hormone (AMH) is a glycoprotein that plays an important role in prenatal sex differentiation. It is used as a biomarker in polycystic ovary syndrome (PCOS) diagnostics, as well as for estimating an individual’s ovarian reserve and the ovarian response to hormonal stimulation during in vitro fertilization (IVF). The aim of this study was to test the stability of AMH during various preanalytical conditions that are in accordance with the ISBER (International Society for Biological and Environmental Repositories) protocol. Plasma and serum samples were taken from each of the 26 participants. The samples were then processed according to the ISBER protocol. AMH levels were measured in all the samples simultaneously using the chemiluminescent kit ACCESS AMH in a UniCel® DxI 800 Immunoassay System (Beckman Coulter, Brea, CA, USA). The study proved that AMH retains a relatively high degree of stability during repeated freezing and thawing in serum. AMH was shown to be less stable in plasma samples. Room temperature proved to be the least suitable condition for the storage of samples before performing the biomarker analysis. During the testing of storage stability at 5–7 °C, the values decreased over time for all the plasma samples but remained stable in the serum samples. We proved that AMH is highly stable under various stress conditions. The anti-Müllerian hormone retained the greatest stability in the serum samples.

BackgroundBiomarkers such as cytokines, chemokines, and soluble activation markers can be unstable when processing of blood is delayed. The stability of various biomarkers in serum and plasma was investigated when unprocessed blood samples were stored for up to 24h at room and refrigerator temperature.MethodsBlood was collected from 16 healthy volunteers. Unprocessed serum, EDTA and heparinized blood was stored at room (20-25°C) and refrigerator temperature (4-8°C) for 0.5, 2, 4, 6, 8, and 24h after collection before centrifugation and separation of serum and plasma. Samples were batch tested for various biomarkers using commercially available immunoassays. Statistically significant changes were determined using the generalized estimating equation.ResultsIFN-γ, sIL-2Rα, sTNF-RII and β2-microglobulin were stable in unprocessed serum, EDTA and heparinized blood samples stored at either room or refrigerator temperature for up to 24h. IL-6, TNF-α, MIP-1β and RANTES were unstable in heparinized blood at room temperature; TNF-α, and MIP-1β were unstable in unprocessed serum at room temperature; IL-12 was unstable in unprocessed serum at refrigerator temperature; and neopterin was unstable in unprocessed EDTA blood at room temperature. IL-1ra was stable only in unprocessed serum at room temperature.ConclusionAll the biomarkers studied, with the exception of IL-1ra, were stable in unprocessed EDTA blood stored at refrigerator temperature for 24h. This indicates that blood for these biomarkers should be collected in EDTA and if delays in processing are anticipated the unseparated blood should be stored at refrigerator temperature until processing.

Corticotropin is notorious for its instability. Whereas several studies have investigated its short-term stability in plasma following venous blood sampling, studies on long-term stability are lacking. Here we investigated the long-term storage stability of corticotropin in ethylenediaminetetraacetic acid containing plasma. Specimens from healthy volunteers (neat, spiked) were stored in polypropylene microcentrifuge tubes with socket screw-caps at −20 °C and −70 °C for up to one and a half years. Corticotropin in plasma was measured using an Abbott research only immunoassay. Separately, specimens from patients were collected during diagnostic routine testing and stored in polystyrene tubes with push-caps at −20 °C for up to 6 years. In these samples corticotropin hormone was measured using the Diasorin corticotropin immunoassay. Storage of specimens at −20 °C or −70 °C for up to one and a half years showed minimal changes (<11%) in corticotropin levels, while storage of patient samples at −20 °C for up to 6 years showed a significant (54%) reduction in corticotropin levels. Corticotropin levels are stable in plasma when stored at −20 °C for one and a half years using the Abbott research only assay, but with longer storage time a significant reduction in corticotropin levels can be expected. Once specimens are stored for future corticotropin measurements, one should consider storage time, storage temperature and assay differences. [ABSTRACT FROM AUTHOR]

Background. The pharmacokinetics of ponazuril have been determined in several species; however, there is very little information on the stability of the drug after storage for long periods of time. This study was undertaken to determine the stability of ponazuril in plasma samples stored at −80 ◦C, which is the temperature most commonly used in the author’s laboratory. Method. Spiked plasma samples (0.3, 7.5, and 15 µg/mL) were stored at −80 ◦C for three months. Analysis occurred on the first day and then once a week for the following twelve weeks. The drug was extracted using a chloroform extraction and separated by high performance liquid chromatography using ultraviolet detection. Results. There was no loss of drug for any concentration for the first four weeks of storage. There was an average loss of less than 5% from day 35 through day 70 and an average loss of 6% on day 77 and 84. The data suggest that ponazuril is stable for 4 weeks when stored at −80 ◦C and undergoes minimal loss in the remaining 8 weeks. [ABSTRACT FROM AUTHOR]

Background The pharmacokinetics of ponazuril have been determined in several species; however, there is very little information on the stability of the drug after storage for long periods of time. This study was undertaken to determine the stability of ponazuril in plasma samples stored at −80 °C, which is the temperature most commonly used in the author’s laboratory. Method Spiked plasma samples (0.3, 7.5, and 15 µg/mL) were stored at −80 °C for three months. Analysis occurred on the first day and then once a week for the following twelve weeks. The drug was extracted using a chloroform extraction and separated by high performance liquid chromatography using ultraviolet detection. Results There was no loss of drug for any concentration for the first four weeks of storage. There was an average loss of less than 5% from day 35 through day 70 and an average loss of 6% on day 77 and 84. The data suggest that ponazuril is stable for 4 weeks when stored at −80 °C and undergoes minimal loss in the remaining 8 weeks.

In this article we study the plasma motion in the transitional layer of a coronal loop randomly driven at one of its footpoints in the thin-tube and thin-boundary-layer (TTTB) approximation. We introduce the average of the square of a random function with respect to time. This average can be considered as the square of the oscillation amplitude of this quantity. Then we calculate the oscillation amplitudes of the radial and azimuthal plasma displacement as well as the perturbation of the magnetic pressure. We find that the amplitudes of the plasma radial displacement and the magnetic-pressure perturbation do not change across the transitional layer. The amplitude of the plasma radial displacement is of the same order as the driver amplitude. The amplitude of the magnetic-pressure perturbation is of the order of the driver amplitude times the ratio of the loop radius to the loop length squared. The amplitude of the plasma azimuthal displacement is of the order of the driver amplitude times Re 1 / 6 , where Re is the Reynolds number. It has a peak at the position in the transitional layer where the local Alfvén frequency coincides with the fundamental frequency of the loop kink oscillation. The ratio of the amplitude near this position and far from it is of the order of ℓ , where ℓ is the ratio of thickness of the transitional layer to the loop radius. We calculate the dependence of the plasma azimuthal displacement on the radial distance in the transitional layer in a particular case where the density profile in this layer is linear. [ABSTRACT FROM AUTHOR]

We study kink oscillations of a straight magnetic tube in the presence of siphon flows. The tube consists of a core and a transitional or boundary layer. The flow velocity is parallel to the tube axis, has constant magnitude, and confined in the tube core. The plasma density is constant in the tube core and it monotonically decreases in the transitional layer to its value in the surrounding plasma. We use the expression for the decrement/increment previously obtained by Ruderman and Petrukhin (Astron. Astrophys.631, A31, 2019) to study the damping and resonant instability of kink oscillations. We show that, depending on the magnitude of siphon-velocity, resonant absorption can cause either the damping of kink oscillations or their enhancement. There are two threshold velocities: When the flow velocity is below the first threshold velocity, kink oscillations damp. When the flow velocity is above the second threshold velocity, the kink oscillation amplitudes grow. Finally, when the flow velocity is between the two threshold velocities, the oscillation amplitudes do not change. We apply the theoretical result to kink oscillations of prominence threads. We show that, for particular values of thread parameters, resonant instability can excite these kink oscillations. [ABSTRACT FROM AUTHOR]