Associations between serum and plasma brain-derived neurotrophic factor and influence of storage time and centrifugation strategy.
Author(s): Gejl AK, Enevold C, Bugge A, Andersen MS, Nielsen CH, Andersen LB
Publication: Sci Rep, 2019, Vol. 9, Page 9655
PubMed ID: 31273250 PubMed Review Paper? No
Purpose of Paper
This paper compared brain-derived neurotrophic factor (BDNF) levels in serum, plasma, and platelet-poor plasma (PPP) exposed to a 30-300 min delay to centrifugation. The effects of waist circumference and cardiopulmonary fitness on BDNF levels were also examined.
Conclusion of Paper
BDNF levels were significantly higher in serum than plasma and in plasma than in PPP. Delayed centrifugation significantly affected BDNF levels but differences were not systematic and few differences were found between time-points. BDNF levels were generally correlated between time-points for each of the specimen types and between plasma and PPP, but levels in serum were not correlated with those in PPP or plasma. Waist circumference and BDNF levels in serum with a ≥ 60 min delay to centrifugation were modestly correlated but there was no correlation with plasma BDNF levels. Cardiorespiratory fitness was not correlated with BDNF levels, regardless of centrifugation delay and specimen type, but was modestly negatively correlated with waist circumference.
Studies
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Study Purpose
This study compared BDNF levels in serum, plasma, and PPP exposed to a 30-300 min delay to centrifugation. The effects of waist circumference and cardiopulmonary fitness on BDNF levels were also examined. Blood was collected using a 21-gauge needle from 17 fasting healthy male University students (mean age 25.2 years) into five serum and 10 EDTA plasma Vacutainer tubes. Serum tubes were allowed to clot at room temperature for 30, 60, 180, 240, or 300 min before isolation of serum by centrifugation at 1000 x g for 15 min. EDTA tubes were stored on ice for 30, 60, 180, 240, or 300 min before isolation of plasma by refrigerated centrifugation at 1500 x g for 15 min (normal plasma). Five plasma specimens were subjected to a second refrigerated centrifugation at 10,000 x g for 10 min (platelet-poor plasma, PPP). All plasma and serum specimens were aliquoted and stored at -80˚C for approximately 8 months before determination of BDNF levels using the Biosensis BDNF Rapid ELISA kit. Cardiorespiratory fitness was determined using an ergometer with directly measured oxygen uptake. Waist circumference was measured using anthropometric tape.
Summary of Findings:
BDNF levels were significantly higher in serum than plasma and in plasma than in PPP (P≤0.004, all). Delayed centrifugation significantly affected BDNF levels in serum (P<0.001), plasma (P=0.001), and PPP (P=0.038) but differences were not systematic. Further, significant differences between adjacent time-points were limited to an increase between 30 and 60 min in serum (P<0.05) and 240 min and 300 min in PPP (P=0.048). Further, differences in BDNF levels at each time-point varied among the 17 individuals. BDNF levels in serum with 30 min clot time were modestly correlated with those in serum with a 60, 240, or 300 min clot (r=0.61, r=0.55, and r=0.57; respectively), but were not correlated with serum levels after 120 min clot time or with plasma or PPP levels, regardless of delay. PPP BDNF levels were strongly to very strongly correlated with each other regardless of the delay to centrifugation (r=0.76-0.99, P<0.05) and were modestly to strongly correlated with those in plasma (r=0.49-0.85, P<0.05) with one exception (180 min delay in centrifugation for plasma and 30 min delay in PPP). BDNF levels in normal plasma were modestly to very strongly correlated between delay times (r=0.52-0.91, P<0.05), but were not correlated between plasma obtained after a 60 min delay and after a 300 min delay. Waist circumference and BDNF level in serum with a ≥ 60 min delay to centrifugation were modestly correlated (r=0.49-0.58, P<0.05), but there was no correlation with plasma or PPP BDNF levels. While there was no correlation in cardiorespiratory fitness and BDNF levels, regardless of centrifugation delay and specimen type, there was a modest negative correlation of cardiorespiratory fitness with waist circumference (r=-0.66, P<0.05).
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Preaquisition Diagnosis/ patient condition Different waist circumference
Different cardiopulmonary fitness levels
Biospecimen Aliquots and Components Blood and blood products Plasma
Platelet-poor plasma
Serum
ELISA Specific Targeted peptide/protein BDNF
Storage Storage duration 30 min
60 min
120 min
240 min
300 min
Biospecimen Aliquots and Components Centrifugation Centrifugation delays investigated