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Serum neurofilament light chain withstands delayed freezing and repeated thawing.

ABSTRACT: Serum neurofilament light chain (sNfL) and its ability to expose axonal damage in neurologic disorders have solicited a considerable amount of attention in blood biomarker research. Hence, with the proliferation of high-throughput assay technology, there is an imminent need to study the pre-analytical stability of this biomarker. We recruited 20 patients with common neurological diagnoses and 10 controls (i.e. patients without structural neurological disease). We investigated whether a variation in pre-analytical variables (delayed freezing up to 24 h and repeated thawing/freezing for up to three cycles) affects the measured sNfL concentrations using state of the art Simoa technology. Advanced statistical methods were applied to expose any relevant changes in sNfL concentration due to different storing and processing conditions. We found that sNfL concentrations remained stable when samples were frozen within 24 h (mean absolute difference 0.2 pg/ml; intraindividual variation below 0.1%). Repeated thawing and re-freezing up to three times did not change measured sNfL concentration significantly, either (mean absolute difference 0.7 pg/ml; intraindividual variation below 0.2%). We conclude that the soluble sNfL concentration is unaffected at 4-8 °C when samples are frozen within 24 h and single aliquots can be used up to three times. These observations should be considered for planning future studies.

SUBMITTER: Altmann P

PROVIDER: S-EPMC7672085 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Serum neurofilament light chain withstands delayed freezing and repeated thawing.

Altmann Patrick P Leutmezer Fritz F Zach Heidemarie H Wurm Raphael R Stattmann Miranda M Ponleitner Markus M Petzold Axel A Zetterberg Henrik H Berger Thomas T Rommer Paulus P Bsteh Gabriel G

Scientific reports 20201117 1

Serum neurofilament light chain (sNfL) and its ability to expose axonal damage in neurologic disorders have solicited a considerable amount of attention in blood biomarker research. Hence, with the proliferation of high-throughput assay technology, there is an imminent need to study the pre-analytical stability of this biomarker. We recruited 20 patients with common neurological diagnoses and 10 controls (i.e. patients without structural neurological disease). We investigated whether a variation ...[more]

PMID: 33203974

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Project description:ImportancePrognostication of neurologic outcome after cardiac arrest is an important but challenging aspect of patient therapy management in critical care units.ObjectiveTo determine whether serum neurofilament light chain (NFL) levels can be used for prognostication of neurologic outcome after cardiac arrest.Design, setting and participantsProspective clinical biobank study of data from the randomized Target Temperature Management After Cardiac Arrest trial, an international, multicenter study with 29 participating sites. Patients were included between November 11, 2010, and January 10, 2013. Serum NFL levels were analyzed between August 1 and August 23, 2017, after trial completion. A total of 782 unconscious patients with out-of-hospital cardiac arrest of presumed cardiac origin were eligible.ExposuresSerum NFL concentrations analyzed at 24, 48, and 72 hours after cardiac arrest with an ultrasensitive immunoassay.Main outcomes and measuresPoor neurologic outcome at 6-month follow-up, defined according to the Cerebral Performance Category Scale as cerebral performance category 3 (severe cerebral disability), 4 (coma), or 5 (brain death).ResultsOf 782 eligible patients, 65 patients (8.3%) were excluded because of issues with aliquoting, missing sampling, missing outcome, or transport problems of samples. Of the 717 patients included (91.7%), 580 were men (80.9%) and median (interquartile range [IQR]) age was 65 (56-73) years. A total of 360 patients (50.2%) had poor neurologic outcome at 6 months. Median (IQR) serum NFL level was significantly increased in the patients with poor outcome vs good outcome at 24 hours (1426 [299-3577] vs 37 [20-70] pg/mL), 48 hours (3240 [623-8271] vs 46 [26-101] pg/mL), and 72 hours (3344 [845-7838] vs 54 [30-122] pg/mL) (P < .001 at all time points), with high overall performance (area under the curve, 0.94-0.95) and high sensitivities at high specificities (eg, 69% sensitivity with 98% specificity at 24 hours). Serum NFL levels had significantly greater performance than the other biochemical serum markers (ie, tau, neuron-specific enolase, and S100). At comparable specificities, serum NFL levels had greater sensitivity for poor outcome compared with routine electroencephalogram, somatosensory-evoked potentials, head computed tomography, and both pupillary and corneal reflexes (ranging from 29.2% to 49.0% greater for serum NFL level).Conclusions and relevanceFindings from this study suggest that the serum NFL level is a highly predictive marker of long-term poor neurologic outcome at 24 hours after cardiac arrest and may be a useful complement to currently available neurologic prognostication methods.

Project description:ImportanceUnrecognized demyelinating events often precede the clinical onset of multiple sclerosis (MS). Identification of these events at the time of occurrence would have implications for early diagnosis and the search of causal factors for the disease.ObjectiveTo assess whether serum neurofilament light chain (sNfL) levels are elevated before the clinical MS onset.Design, setting, and participantsNested case-control study among US military personnel who have serum samples stored in the US Department of Defense Serum Repository. Serum samples were collected from 2000 to 2011; sNfL assays and data analyses were performed from 2018 to 2019. We selected 60 case patients with MS who either had 2 samples collected before onset (mean follow-up, 6.3 years) or 1 sample collected before and 1 after onset (mean follow-up, 1.3 years), among 245 previously identified case patients. For each case, we randomly selected 1 of 2 previously identified control individuals matched by age, sex, race/ethnicity, and dates of sample collection. The sample size was chosen based on the available funding.ExposuresSerum NfL concentrations measured using an ultrasensitive single-molecule array assay (Simoa).Main outcomes and measurementsLog-transformed sNfL concentrations in case patients and control individuals compared using conditional logistic regression and linear mixed models.ResultsMean age at baseline was 27.5 years, and 92 of 120 participants (76.7%) were men. Serum NfL levels were higher in case patients with MS compared with their matched control individuals in samples drawn a median of 6 years (range, 4-10 years) before the clinical onset (median, 16.7 pg/mL; interquartile range [IQR], 12.6-23.1 pg/mL vs 15.2 pg/m; IQR, 10.3-19.9 pg/mL; P = .04). This difference increased with decreasing time to the case clinical onset (estimated coefficient for interaction with time = 0.063; P = .008). A within-person increase in presymptomatic sNfL levels was associated with higher MS risk (rate ratio for ≥5 pg/mL increase, 7.50; 95% CI, 1.72-32.80). The clinical onset was associated with a marked increase in sNfL levels (median, 25.0; IQR, 17.1-41.3 vs 45.1; IQR, 27.0-102.7 pg/mL for presymptomatic and postonset MS samples; P = .009).Conclusions and relevanceThe levels of sNfL were increased 6 years before the clinical MS onset, indicating that MS may have a prodromal phase lasting several years and that neuroaxonal damage occurs already during this phase.

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Serum neurofilament light chain withstands delayed freezing and repeated thawing.

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Serum neurofilament light chain withstands delayed freezing and repeated thawing.

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