scholarly journals Pre-Analytical Factors that Affect Metabolite Stability in Human Urine, Plasma, and Serum: A Review

Metabolites ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 156 ◽  
Author(s):  
Victoria L. Stevens ◽  
Elise Hoover ◽  
Ying Wang ◽  
Krista A. Zanetti
Keyword(s):  
Small Molecules ◽  
Room Temperature ◽  
Epidemiological Studies ◽  
Serum Samples ◽  
Time Processing ◽  
Freeze Thaw ◽  
Standardized Protocol ◽  
Metabolite Stability ◽  
Collection Time ◽  
Serum And Urine

Metabolomics provides a comprehensive assessment of numerous small molecules in biological samples. As it integrates the effects of exogenous exposures, endogenous metabolism, and genetic variation, metabolomics is well-suited for studies examining metabolic profiles associated with a variety of chronic diseases. In this review, we summarize the studies that have characterized the effects of various pre-analytical factors on both targeted and untargeted metabolomic studies involving human plasma, serum, and urine and were published through 14 January 2019. A standardized protocol was used for extracting data from full-text articles identified by searching PubMed and EMBASE. For plasma and serum samples, metabolomic profiles were affected by fasting status, hemolysis, collection time, processing delays, particularly at room temperature, and repeated freeze/thaw cycles. For urine samples, collection time and fasting, centrifugation conditions, filtration and the use of additives, normalization procedures and multiple freeze/thaw cycles were found to alter metabolomic findings. Consideration of the effects of pre-analytical factors is a particularly important issue for epidemiological studies where samples are often collected in nonclinical settings and various locations and are subjected to time and temperature delays prior being to processed and frozen for storage.

Free and total insulin as determined after precipitation with polyethylene glycol: analytical characteristics and effects of sample handling and storage.

1987 ◽  
Vol 33 (1) ◽  
pp. 93-96 ◽  
Author(s):  
H Arnqvist ◽  
P O Olsson ◽  
H von Schenck
Keyword(s):  
Polyethylene Glycol ◽  
Room Temperature ◽  
Serum Samples ◽  
Sample Handling ◽  
Insulin In Plasma ◽  
Analytical Recovery ◽  
Free Insulin ◽  
Assay Precision ◽  
And Storage ◽  
Collection Time

Abstract We evaluated results of radioimmunoassays of free and total insulin after precipitation of endogenous antibodies with polyethylene glycol (PEG), and we investigated the influence of collection time, temperature, and storage in heparin- cr EDTA-treated plasma or serum on results for free insulin. Analytical recovery of free insulin was 99.3%, of total insulin 96.4%. For free insulin, assay precision (CV) was 4.0-13.0% (intra-assay) and 7.8-10.7% (inter-assay); for total insulin, 3.6-9.5% and 6.6-11.7%, respectively. Free insulin decreased in plasma (p less than 0.05) and serum (p less than 0.01) at room temperature after 3 h and in promptly analyzed serum (p less than 0.01). Storage of samples at -20 degrees C increased the concentration of free insulin in plasma (p less than 0.025) and serum (p less than 0.005), whereas the free insulin content of supernates after PEG precipitation was stable, except for a slight decrease in serum samples (p less than 0.02). We conclude that, for radioimmunoassay of free and total insulin, plasma should be used, treated with PEG without delay; supernates then are analytically stable for as long as 26 weeks at -20 degrees C.

scholarly journals Stability of important antibodies for kidney disease: pre-analytic methodological considerations

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5178
Author(s):  
Qiuxia Han ◽  
Songyan Li ◽  
Bo Fu ◽  
Dongwei Liu ◽  
Maoqing Wu ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Room Temperature ◽  
Physical Disturbance ◽  
Serum Samples ◽  
Freeze Thaw ◽  
Long Term Storage ◽  
Circulating Antibodies ◽  
And Storage ◽  
Term Storage

BackgroundThe importance of circulating antibodies as biomarkers of kidney disease has recently been recognized. However, no study has systematically described the methodology of sample preparation and storage regarding antibodies as biomarkers of kidney disease. It remains unknown whether repetitive freeze-thaw cycles, physical disturbances, storage at different temperatures or for different periods of time, or haemolytic or turbid serum samples affect antibody measurements. The aim of this study was to investigate the stabilities of antibodies associated with kidney disease in serum samples under various relevant clinical and research conditions.MethodsWe stored serum samples in the following different conditions: repetitive freeze-thaw cycles (1, 6 or 12 times), long-term storage (7 or 12 months at −80 °C), physical disturbance (1 or 8 h), and storage at 4 °C (1, 3 or 6 weeks) and room temperature (1 or 7 days). The stabilities of the anti-phospholipase A2 receptor (anti-PLA2R), anti-glomerular basement membrane, anti-myeloperoxidase and anti-proteinase 3 antibodies were evaluated with enzyme-linked immunosorbent assays (ELISA).ResultsWe found that repetitive freeze-thaw cycles did not have a significant effect on the stabilities of the abovementioned antibodies in clear serum samples. The ELISA readings of haemolytic and turbid serum samples tended to increase and decrease, respectively. Neither long-term storage at −80 °C nor physical disturbance had a significant effect on anti-PLA2R antibody stability in sealed serum samples. The concentrations of most of these antibodies increased in unsealed serum samples that were stored at 4 °C for more than 6 weeks or at room temperature for more than 7 days.DiscussionOur findings revealed that the abovementioned circulating antibodies that are used as biomarkers for kidney disease had stable physicochemical properties, structures and immunoreactivities such that they were not influenced by repetitive freeze-thaw cycles, physical disturbances or long-term storage at −80 °C. However, the ELISA readings tended to change for haemolytic, turbid and unsealed serum samples.

Effect of Freezing and Thawing of Serum on the Immunoassay of Lipoprotein(a)

1992 ◽  
Vol 38 (9) ◽  
pp. 1873-1877 ◽  
Author(s):  
D S Sgoutas ◽  
T Tuten
Keyword(s):  
Room Temperature ◽  
Enzyme Linked Immunosorbent Assay ◽  
Freezing And Thawing ◽  
Serum Samples ◽  
Lipoprotein A ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Quick Freezing ◽  
Freeze Thaw Cycle

Abstract We studied the effect of freezing and thawing of serum on the determination of lipoprotein(a) [Lp(a)] with a commercial enzyme-linked immunosorbent assay (ELISA) and an immunoturbidimetric assay (ITA). Portions of sera from 11 apparently healthy persons and pooled sera, from an additional 10 subjects were frozen at either -20 or -70 degrees C and thawed at room temperature. Cycles of freezing and thawing were repeated during the experiments (1 month). Samples were assayed for Lp(a) after thawing. Pooled sera were subjected to quick freezing at -70 degrees C and thawing at room temperature in cycles. Results show a significant (P less than 0.05) decrease in Lp(a) concentration in sera subjected to freezing and thawing. Samples thawed from -20 degrees C gave concentrations by ELISA that were significantly lower than those of fresh samples after one freeze-thaw cycle. By ITA the decrease was significant only after two cycles. In specimens frozen at -70 degrees C, Lp(a) concentrations determined by ELISA decreased after two cycles, and by ITA after three freeze-thaw cycles. Serum samples subjected to quick freezing at -70 degrees C and thawing did not show significant decreases in Lp(a) immunoreactivity during four cycles. Immunoreactivity of Lp(a) in samples stored at 4 degrees C decreased after 6 days but fell faster in serum samples subjected to freezing and thawing before storage at 4 degrees C.

scholarly journals Evaluation of a Pseudovirus Neutralization Assay for SARS-CoV-2 and Correlation with Live Virus-Based Micro Neutralization Assay

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 994
Author(s):  
Ahmed Majdi K. Tolah ◽  
Sayed S. Sohrab ◽  
Khaled Majdi K. Tolah ◽  
Ahmed M. Hassan ◽  
Sherif A. El-Kafrawy ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Epidemiological Studies ◽  
Neutralization Assay ◽  
Serum Samples ◽  
Live Virus ◽  
Spike Gene ◽  
Microneutralization Assay ◽  
Viral Particles ◽  
Reliable Performance ◽  
Prior Infection

The unusual cases of pneumonia outbreak were reported from Wuhan city in late December 2019. Serological testing provides a powerful tool for the identification of prior infection and for epidemiological studies. Pseudotype virus neutralization assays are widely used for many viruses and applications in the fields of serology. The accuracy of pseudotype neutralizing assay allows for its use in low biosafety lab and provides a safe and effective alternative to the use of wild-type viruses. In this study, we evaluated the performance of this assay compared to the standard microneutralization assay as a reference. The lentiviral pseudotype particles were generated harboring the Spike gene of SARS-CoV-2. The generated pseudotype particles assay was used to evaluate the activity of neutralizing antibodies in 300 human serum samples from a COVID-19 sero-epidemiological study. Testing of these samples resulted in 55 positive samples and 245 negative samples by pseudotype viral particles assay while microneutralization assay resulted in 64 positive and 236 negative by MN assay. Compared to the MN, the pseudotyped viral particles assay showed a sensitivity of 85.94% and a specificity of 100%. Based on the data generated from this study, the pseudotype-based neutralization assay showed a reliable performance for the detection of neutralizing antibodies against SARS-CoV-2 and can be used safely and efficiently as a diagnostic tool in a biosafety level 2 laboratory.

scholarly journals Metabolomics Studies in Psoriatic Disease: A Review

Metabolites ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 375
Author(s):  
John Koussiouris ◽  
Nikita Looby ◽  
Melanie Anderson ◽  
Vathany Kulasingam ◽  
Vinod Chandran
Keyword(s):  
Psoriatic Arthritis ◽  
Small Molecules ◽  
Web Of Science ◽  
Citation Index ◽  
Cochrane Central Register ◽  
Psoriatic Disease ◽  
Ovid Medline ◽  
Standardized Protocol ◽  
Central Register ◽  
Endogenous Metabolites

Metabolomics investigates a broad range of small molecules, allowing researchers to understand disease-related changes downstream of the genome and proteome in response to external environmental stimuli. It is an emerging technology that holds promise in identifying biomarkers and informing the practice of precision medicine. In this review, we summarize the studies that have examined endogenous metabolites in patients with psoriasis and/or psoriatic arthritis using nuclear magnetic resonance (NMR) or mass spectrometry (MS) and were published through 26 January 2021. A standardized protocol was used for extracting data from full-text articles identified by searching OVID Medline ALL, OVID Embase, OVID Cochrane Central Register of Controlled Trials and BIOSIS Citation Index in Web of Science. Thirty-two studies were identified, investigating various sample matrices and employing a wide variety of methods for each step of the metabolomics workflow. The vast majority of studies identified metabolites, mostly amino acids and lipids that may be associated with psoriasis diagnosis and activity. Further exploration is needed to identify and validate metabolomic biomarkers that can accurately and reliably predict which psoriasis patients will develop psoriatic arthritis, differentiate psoriatic arthritis patients from patients with other inflammatory arthritides and measure psoriatic arthritis activity.

Development of an HPLC method for measuring orally administered 1-substituted 2-alkyl-3-hydroxypyrid-4-one iron chelators in biological fluids

1990 ◽  
Vol 36 (1) ◽  
pp. 5-8 ◽  
Author(s):  
J G Goddard ◽  
G J Kontoghiorghes
Keyword(s):  
High Performance ◽  
Biological Fluids ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Hplc Method ◽  
Iron Chelators ◽  
Serum Samples ◽  
Thalassemic Patient ◽  
Serum And Urine

Abstract "High-performance" liquid-chromatographic (HPLC) methods have been developed for identifying 1-substituted 2-alkyl-3-hydroxypyrid-4-one iron chelators in serum and urine. Ion pairing with heptane- or octanesulfonic acid in pH 2.0-2.2 phosphate buffer and reversed-phase chromatography were required to separate these compounds from endogenous compounds in both biological fluids. In both the 2-methyl and 2-ethyl series of 1-substituted compounds (H, methyl, ethyl, or propyl) the elution times increased in accordance with the n-octanol/water partition coefficients (propyl greater than ethyl greater than H greater than methyl). Urine samples were filtered (0.4 microns pore size) and injected either undiluted or after dilution with elution buffer. After the addition of internal standard, the plasma or serum samples were deproteinized by treatment with HCIO4, 0.5 mol/L, centrifuged, and the supernates were injected directly onto the HPLC. Using these procedures, we could identify 1,2-dimethyl-3-hydroxypyrid-4-one (L1) in the serum and urine of a thalassemic patient who had received a 3-g dose of the drug and in the urine of other patients who had received the same dose. One or more possible metabolites were also observed in the chromatograms of both urine and serum. The 24-h urinary output of L1 (0.22-2.37 g) and iron (10.6-71.5 mg) varied but there was no correlation between the two with respect to quantity or concentration. Instead, urinary iron output was higher in patients with a greater number of transfused units of erythrocytes. This is the first study in humans to show that L1 is absorbed from the gut, enters the circulation, and is excreted in the urine.

Lipoprotein(a) and postmenopausal oestrogen

1993 ◽  
Vol 129 (3) ◽  
pp. 225-228 ◽  
Author(s):  
Elizabeth Farish ◽  
Hilary A Rolton ◽  
Judith F Barnes ◽  
Colin D Fletcher ◽  
David J Walsh ◽  
...  
Keyword(s):  
Marked Effect ◽  
Density Lipoprotein ◽  
Epidemiological Studies ◽  
Oestrogen Therapy ◽  
Bilateral Oophorectomy ◽  
Short Term ◽  
Serum Samples ◽  
Lipoprotein A ◽  
Before And After ◽  
Unopposed Oestrogen

Epidemiological studies have shown that postmenopausal oestrogen therapy substantially reduces the risk of cardiovascular and cerebrovascular disease and this is partly mediated by oestrogen-associated changes in lipoproteins, particularly high-density lipoprotein. In this study, we investigated whether changes in lipoprotein(a) might help to account for the reduction in coronary heart disease and stroke associated with postmenopausal oestrogen therapy. The study group consisted of 18 women who had hysterectomy and bilateral oophorectomy at least 2 months prior to recruitment and had received no previous hormonal therapy. Serum samples were collected for measurement of lipoprotein(a) before and after 4 months of treatment with oestradiol valerate (2 mg/day). Lipoprotein(a) levels ranged from 35 to 720 mg/l (median 180 mg/l) before treatment and from 55 to 780 mg/l (median 1 30 mg/l) after oestradiol treatment and showed no consistent pattern of change. It would appear, therefore, that treatment with unopposed oestrogen in relatively low doses does not have a marked effect on lipoprotein(a), at least in the short term.

scholarly journals Circulating Levels of Free 25(OH)D Increase at the Onset of Rheumatoid Arthritis

2019 ◽  
Author(s):  
Vidyanand Anaparti ◽  
Xiaobo Meng ◽  
Hemsekhar Mahadevappa ◽  
Irene Smolik ◽  
Neeloffer Mookherjee ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Vitamin D ◽  
Linear Regression Analysis ◽  
Autoimmune Disorder ◽  
Joint Inflammation ◽  
Epidemiological Studies ◽  
Vitamin D Metabolites ◽  
Serum Samples ◽  
Hs Crp ◽  
Circulating Levels

ABSTRACTObjectiveEpidemiological studies suggest vitamin D deficiency as a potential risk factor for rheumatoid arthritis (RA) development, a chronic autoimmune disorder highly prevalent in indigenous North American (INA) population. We therefore profiled the circulating levels of 25-hydroxyvitaminD [25(OH)D], an active metabolite of vitamin D, in a cohort of at-risk first-degree relatives (FDR) of INA RA patients, a subset of whom subsequently developed RA (progressors).Methods2007 onward, serum samples from INA RA patients and FDR were collected at the time of a structured baseline visit and stored at −20°C. Anti-citrullinated protein antibodies (ACPA), 25(OH)D, hs-CRP, vitamin-D binding protein (VDBP) levels were determined using ELISA and rheumatoid factor (RF) seropositivity was determined by nephelometry.ResultsWe demonstrate that 25 (OH) D concentrations were lower in winter than summer (P=0.0538), and that serum 25(OH)D levels were higher in samples collected and stored after 2013 (P<0.0001). Analysis of samples obtained after 2013 demonstrated that 37.6% of study participants were 25(OH)D insufficient (<75nmol/L). Also, seropositive RA patients and FDR had lower 25(OH)D levels compared to ACPA-/FDR (P<0.05, P<0.01 respectively). Linear regression analysis showed 25(OH)D insufficiency was inversely associated with presence of RA autoantibodies. Longitudinal samples from 14 progressors demonstrated a consistent increase in 25(OH)D levels at the time they exhibited clinically detectable joint inflammation, without any significant change in VDBP levels.ConclusionWe demonstrate that 25(OH)D levels in serum increased at RA onset in progressors. The potential role that vitamin D metabolites and their downstream effects play in RA transition requires further investigation.

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