Phenotyping of Hyperlipoproteinemias

Abstract The stability of serum specimens collected for cellulose acetate electrophoresis of lipoproteins has been studied for each of the hyperlipoproteinemia phenotypes. In general, samples kept at room temperature for three days are still suitable for analysis. On longer standing, artifacts can cause misinterpretation of strips, or render them completely unreadable. If specimens are stored at refrigerator or freezer temperatures, deterioration is retarded but the period of stability after they are returned to room temperature is unaltered. A second freeze-thaw cycle makes specimens unsuitable for analysis. Samples can be stored at refrigerator temperatures for at least 28 days and at freezer temperatures for at least 14 days if one freeze-thaw cycle is used.

Download Full-text

The Effect of Freeze/Thaw Cycles on the Stability of Compounds in DMSO

CrossRef Listing of Deleted DOIs ◽

10.1177/1087057103252618 ◽

2003 ◽

Vol 8 (2) ◽

pp. 210-215 ◽

Cited By ~ 66

Author(s):

Barbara A. Kozikowski ◽

Thomas M. Burt ◽

Debra A. Tirey ◽

Lisa E. Williams ◽

Barbara R. Kuzmak ◽

...

Keyword(s):

High Throughput Screening ◽

High Performance ◽

Atmospheric Conditions ◽

Freeze Thaw ◽

Thaw Cycle ◽

Time Period ◽

Freeze Thaw Cycle ◽

Low Humidity ◽

The Stability ◽

Short Time

A diverse set of 320 compounds from the Procter & Gamble Pharmaceuticals organic compound repository was prepared as 20-mM DMSO solutions and stored at 4°C under argon in pressurized canisters to simulate a low-humidity environment. The plates were subjected to 25 freeze/thaw cycles while being exposed to ambient atmospheric conditions after each thaw to simulate the time and manner by which compound plates are exposed to the atmosphere during typical liquid-handling and high-throughput screening processes. High-performance liquid chromatography–mass spectrometry with evaporative light-scattering detection was used to quantitate the amount of compound remaining after every 5th freeze/thaw cycle. Control plates were stored either at room temperature under argon or at 4°C under argon without freeze/thaw cycling and were evaluated at the midpoint and the endpoint of the study. The study was conducted over a short time period (i.e., 7 weeks) to minimize the effect of compound degradation over time due to the exposure of the compounds to DMSO.The results from this study will be used to determine the maximum number of freeze/thaw cycles that can be achieved while maintaining acceptable compound integrity.(Journal of Biomolecular Screening 2003:210-215)

Download Full-text

Stability of Plasma Amyloid-β 1–40, Amyloid-β 1–42, and Total Tau Protein over Repeated Freeze/Thaw Cycles

Dementia and Geriatric Cognitive Disorders Extra ◽

10.1159/000506278 ◽

2020 ◽

Vol 10 (1) ◽

pp. 46-55

Author(s):

Huei-Chun Liu ◽

Ming-Jang Chiu ◽

Chin-Hsien Lin ◽

Shieh-Yueh Yang

Keyword(s):

Tau Protein ◽

Statistical Significance ◽

Amyloid Β ◽

Freeze Thaw ◽

Total Tau ◽

Thaw Cycle ◽

Freeze Thaw Cycle ◽

Fresh Plasma ◽

The Stability ◽

T Tau

Introduction: Blood biomarkers of Alzheimer’s disease (AD) have attracted much attention of researchers in recent years. In clinical studies, repeated freeze/thaw cycles often occur and may influence the stability of biomarkers. This study aims to investigate the stability of amyloid-β 1–40 (Aβ1–40), amyloid-β 1–42 (Aβ1–42), and total tau protein (T-tau) in plasma over freeze/thaw cycles. Methods: Plasma samples from healthy controls (n = 2), AD patients (AD, n =3) and Parkinson’s disease patients (PD, n = 3) were collected by standardized procedure and immediately frozen at –80°C. Samples underwent 5 freeze/thaw (–80°C/room temperature) cycles. The concentrations of Aβ1–40, Aβ1–42, and T-tau were monitored during the freeze/thaw tests using an immunomagnetic reduction (IMR) assay. The relative percentage of concentrations after every freeze/thaw cycle was calculated for each biomarker. Results: A tendency of decrease in the averaged relative percentages over samples through the freeze and thaw cycles for Aβ1–40 (100 to 97.11%), Aβ1–42 (100 to 94.99%), and T-tau (100 to 95.65%) was found. However, the decreases were less than 6%. For all three biomarkers, no statistical significance was found between the levels of fresh plasma and those of the plasma experiencing 5 freeze/thaw cycles (p > 0.1). Conclusions: Plasma Aβ1–40, Aβ1–42, and T-tau are stable through 5 freeze/thaw cycles measured with IMR.

Download Full-text

The Effects of a Single Freeze-Thaw Cycle on Concentrations of Nutritional, Noncommunicable Disease, and Inflammatory Biomarkers in Serum Samples

Journal of Laboratory Physicians ◽

10.1055/s-0041-1726575 ◽

2021 ◽

Author(s):

Ransi Ann Abraham ◽

Garima Rana ◽

Praween K. Agrawal ◽

Robert Johnston ◽

Avina Sarna ◽

...

Keyword(s):

Large Scale ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Noncommunicable Disease ◽

Noncommunicable Diseases ◽

Serum Samples ◽

Freeze Thaw ◽

Thaw Cycle ◽

Freeze Thaw Cycle ◽

The Stability

Abstract Background The stability of biological samples is vital for reliable measurements of biomarkers in large-scale survey settings, which may be affected by freeze-thaw procedures. We examined the effect of a single freeze-thaw cycle on 13 nutritional, noncommunicable diseases (NCD), and inflammatory bioanalytes in serum samples. Method Blood samples were collected from 70 subjects centrifuged after 30 minutes and aliquoted immediately. After a baseline analysis of the analytes, the samples were stored at − 70°C for 1 month and reanalyzed for all the parameters. Mean percentage differences between baseline (fresh blood) and freeze-thaw concentrations were calculated using paired sample t-tests and evaluated according to total allowable error (TEa) limits (desirable bias). Results Freeze-thaw concentrations differed significantly (p < 0.05) from baseline concentrations for soluble transferrin receptor (sTfR) (− 5.49%), vitamin D (− 12.51%), vitamin B12 (− 3.74%), plasma glucose (1.93%), C-reactive protein (CRP) (3.45%), high-density lipoprotein (HDL) (7.98%), and cholesterol (9.76%), but they were within respective TEa limits. Low-density lipoprotein (LDL) (− 0.67%), creatinine (0.94%), albumin (0.87%), total protein (1.00%), ferritin (− 0.58%), and triglycerides (TAG) (2.82%) concentrations remained stable following the freeze-thaw cycle. In conclusion, single freeze-thaw cycle of the biomarkers in serum/plasma samples after storage at − 70°C for 1 month had minimal effect on stability of the studied analytes, and the changes in concentration were within acceptable limit for all analytes.

Download Full-text

The Effect of Tanreqing Injection on the Pharmacokinetics of Sirolimus in Rats

BioMed Research International ◽

10.1155/2019/1854323 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Feng Zhang ◽

Liang Sun ◽

Jianxiu Zhai ◽

Tianyi Xia ◽

Wei Jiang ◽

...

Keyword(s):

High Performance ◽

Room Temperature ◽

Matrix Effects ◽

Thaw Cycle ◽

Relative Standard ◽

The Matrix ◽

Freeze Thaw Cycle ◽

Liquid Chromatography Tandem Mass ◽

The Stability ◽

First Time

To evaluate the effect of Tanreqing injection on the pharmacokinetics of sirolimus in rats, a high performance liquid chromatography tandem mass spectrometry method was developed for sirolimus assay in whole blood. Calibration curve of sirolimus was acquired over a concentration ranging from 2.5 to 100 ng/mL with r2= 0.9955. The matrix effects and extraction recoveries of sirolimus ranged from 144% to 152% and from 80% to 96%, respectively. The inter- and intraday relative standard deviations were both <10%. The stability investigation showed that the blood samples were stable for 30-day-storage at -20°C, for 8 h storage at room temperature, for 24 h storage in the auto-sampler at 4°C, and for three freeze-thaw cycle process. The pharmacokinetic results demonstrated that the Cmax, AUC, and AUMC of sirolimus in rats (7.5 mg/kg, i.g.) were increased after beincoadministration with Tanreqing Injection at 2.5, 5.0, and 7.5 mL/kg (i.v.), respectively, or at 5 min, 2 h, and 4 h (5.0 mL/kg, i.v.) after SRL dosing, respectively. For the first time, the results proved the herb-drug interaction between Tanreqing Injection and sirolimus and accordingly suggested avoiding concurrent reception of those two drugs for patients.

Download Full-text

The Influence of Regional Freeze–Thaw Cycles on Loess Landslides: Analysis of Strength Deterioration of Loess with Changes in Pore Structure

Water ◽

10.3390/w12113047 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3047

Author(s):

Zuyong Li ◽

Gengshe Yang ◽

Hui Liu

Keyword(s):

Pore Structure ◽

Triaxial Compression ◽

Strength Loss ◽

Loess Landslide ◽

Strength Deterioration ◽

Freeze Thaw ◽

Thaw Cycle ◽

Freeze Thaw Cycle ◽

Loess Landslides ◽

The Stability

The loess landslide in Gaoling District of Xi’an, Shaanxi in China is closely related to the seasonal freeze–thaw cycle, which is manifested by the destruction of pore structure and strength deterioration of the loess body under freeze–thaw conditions. In order to study the relationship between macro-strength damage and pore structure deterioration of saturated loess under freeze–thaw conditions and its influence on the stability of landslides, this paper explores the effect of freeze–thaw cycles on the strength of saturated undisturbed loess through triaxial compression test, and explores the micro-microstructure changes of saturated undisturbed loess through scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). This is to analyze the evolution of the pore structure and strength loss evolution of saturated loess during the freeze–thaw process, and to describe the freeze–thaw damage of saturated undisturbed loess through the change of porosity and strength deterioration. Then, the internal correlation expression between the porosity change and the strength degradation is established to realize the verification analysis of the test data based on the correlation model. The research results show that: (1) As the number of freeze–thaw cycles increases, the peak strength loss rate gradually increases, and the strength deterioration of saturated loess becomes more and more obvious. (2) The freeze–thaw cycle will lead to the development of pores and cracks in the sample, accompanied by the generation of new cracks, which will cause the deterioration of the pore structure of the sample as a whole. (3) The response of strength damage and porosity deterioration of saturated undisturbed loess is roughly similar under the freeze–thaw cycle. The change in porosity can be measured to better reflect the strength deterioration of saturated loess. Therefore, the change of pore structure of undisturbed loess under freeze–thaw cycle conditions is tested by field sampling and indoor tests to reflect the phenomenon of strength deterioration, thereby analyzing the stability of loess slopes.

Download Full-text

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

Clinical Chemistry ◽

10.1093/clinchem/38.9.1873 ◽

1992 ◽

Vol 38 (9) ◽

pp. 1873-1877 ◽

Cited By ~ 24

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.

Download Full-text