scholarly journals Determining Stability of Stored Samples Retrospectively: The Validation of Glycated Albumin

2011 ◽  
Vol 57 (2) ◽  
pp. 286-290 ◽  
Author(s):  
David M Nathan ◽  
Michael W Steffes ◽  
Wanjie Sun ◽  
Gregory P Rynders ◽  
John M Lachin
Keyword(s):  
Linear Model ◽  
Glycated Albumin ◽  
Simple Approach ◽  
Diabetes Control ◽  
Hb A1c ◽  
Time Period ◽  
Sample Stability ◽  
Collection Period ◽  
The Stability

BACKGROUND Determining the stability of stored samples for assays that were not available at the time of original collection is problematic. To assess sample stability for a relatively new assay of glycated albumin (GA), we first measured GA in fresh samples and in samples stored for 19–23 years. We then compared the regression of the contemporaneous glycohemoglobin (Hb A1c) values against the GA results from fresh vs stored samples, reasoning that similar slopes and intercepts would provide strong, albeit indirect, support for the stability of the stored samples for GA measurements. METHODS We assayed 90 samples frozen for 19–23 years and 90 fresh samples from participants in the Diabetes Control and Complications trial cohort for GA. Hb A1c was measured contemporaneously in fresh samples at each time period. A single normal-errors linear model regressed the Hb A1c values on the GA, with an additional effect for collection period (fresh vs stored for GA) and the interaction of period and GA. RESULTS Analysis of the regressions lines between GA and Hb A1c revealed intercepts (3.69 and 2.97 for the fresh and stored samples, respectively) and slopes (0.198 vs 0.187) that were not significantly different (P = 0.182 and P = 0.639, respectively). CONCLUSIONS This simple approach can be used to assess the stability of stored samples in new assays. Samples stored for as long as 23 years are suitable for the GA assay.

A Simple Approach to Evaluating the Stability of Optimal Portfolios

2014 ◽  
Author(s):  
Zhongjin Yang ◽  
Keli Han ◽  
Marat Molyboga ◽  
Georgiy Molyboga
Keyword(s):  
Simple Approach ◽  
Optimal Portfolios ◽  
The Stability

scholarly journals Wormhole Solutions in Symmetric Teleparallel Gravity with Noncommutative Geometry

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1260
Author(s):  
Zinnat Hassan ◽  
Ghulam Mustafa ◽  
Pradyumn Kumar Sahoo
Keyword(s):  
Linear Model ◽  
Noncommutative Geometry ◽  
Teleparallel Gravity ◽  
Exponential Model ◽  
Model Parameter ◽  
Exponential Models ◽  
Feasible Solutions ◽  
The Stability ◽  
Tov Equation

This article describes the study of wormhole solutions in f(Q) gravity with noncommutative geometry. Here, we considered two different f(Q) models—a linear model f(Q)=αQ and an exponential model f(Q)=Q−α1−e−Q, where Q is the non-metricity and α is the model parameter. In addition, we discussed the existence of wormhole solutions with the help of the Gaussian and Lorentzian distributions of these linear and exponential models. We investigated the feasible solutions and graphically analyzed the different properties of these models by taking appropriate values for the parameter. Moreover, we used the Tolman–Oppenheimer–Volkov (TOV) equation to check the stability of the wormhole solutions that we obtained. Hence, we found that the wormhole solutions obtained with our models are physically capable and stable.

scholarly journals Application of Lipid Class Ratios for Sample Stability Monitoring—Evaluation of Murine Tissue Homogenates and SDS as a Stabilizer

Metabolites ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 277
Author(s):  
Sabrina Krautbauer ◽  
Raquel Blazquez ◽  
Gerhard Liebisch ◽  
Marcus Hoering ◽  
Philip Neubert ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Lipid Class ◽  
High Resolution Mass Spectrometry ◽  
Lipolytic Activity ◽  
Sodium Dodecyl ◽  
Lipid Profiles ◽  
Lipolytic Action ◽  
Sample Stability ◽  
Tissue Homogenates ◽  
The Stability

Lipids are a ubiquitous class of structurally complex molecules involved in various biological processes. In the fast-growing field of lipidomics, preanalytical issues are frequently neglected. Here, we investigated the stability of lipid profiles of murine liver, brain, lung, heart, and spleen homogenates by quantitative flow injection analysis using tandem mass spectrometry and high-resolution mass spectrometry. Storage of tissue homogenates at room temperature showed substantial alterations of the lipid profiles reflecting lipolytic action. Therefore, ratios of ceramide to sphingomyelin, lysophosphatidylethanolamine to phosphatidylethanolamine, lysophosphatidylcholine to phosphatidylcholine, and diglyceride to triglyceride were applied to monitor sample stability and the effect of sodium dodecyl sulfate (SDS) as a potential stabilizing agent. The addition of SDS led to a concentration-dependent stabilization of lipid profiles in liver, brain, and heart homogenates, while in lung and spleen homogenates, in particular, the lysophosphatidylethanolamine to phosphatidylethanolamine ratio increased upon addition of SDS. In conclusion, we demonstrated that lipid class ratios reflecting lipolytic activity could be applied to evaluate both the stability of samples and the influence of stabilizers.

Synchronization of Oscillators

2011 ◽  
pp. 247-260
Author(s):  
Jean B. Chabi Orou
Keyword(s):  
Chaotic Synchronization ◽  
Simple Approach ◽  
Short Introduction ◽  
Synchronization Process ◽  
The Stability ◽  
In The Beginning ◽  
Influence Of Noise ◽  
Synchronization Of Oscillators

A simple approach is proposed in this chapter to get started on the synchronization of oscillators study. The basics are given in the beginning such that the reader can get quickly familiar with the main concepts which lead to many kinds of synchronization configurations. Chaotic synchronization is next addressed and is followed by the stability of the synchronization issue. Finally, a short introduction of the influence of noise on the synchronization process is mentioned.

Sample stability: a suggested definition and method of determination.

1976 ◽  
Vol 22 (2) ◽  
pp. 176-183 ◽  
Author(s):  
R E Thiers ◽  
G T Wu ◽  
A H Reed ◽  
L K Oliver
Keyword(s):  
Statistical Design ◽  
Measuring Method ◽  
Chemical Constituent ◽  
Sequential Test ◽  
Method Of Determination ◽  
Sample Stability ◽  
Average Change ◽  
Truncated Normal ◽  
Standard Deviations ◽  
The Stability

Abstract We propose defining the stability of any chemical constituent of stored samples in terms that are quantitatively related to the precision of the measurement by which it is determined. We suggest that a constituent may be considered stable, for a stated period and under exactly defined conditions, when the average change in its measured value is less than a chosen number, K, of standard deviations of the data obtained by the measuring method over the concentration range in question. Based on this definition a technique utilizing a graphical truncated normal sequential test is presented as the appropriate experimental and statistical design for measuring stability. The statistical basis for the proposal is presented.

scholarly journals Associations of Cardiac, Kidney, and Diabetes Biomarkers With Peripheral Neuropathy among Older Adults in the Atherosclerosis Risk in Communities (ARIC) Study

2020 ◽  
Vol 66 (5) ◽  
pp. 686-696 ◽  
Author(s):  
Caitlin W Hicks ◽  
Dan Wang ◽  
Natalie R Daya ◽  
B Gwen Windham ◽  
Christie M Ballantyne ◽  
...  
Keyword(s):  
Older Adults ◽  
Peripheral Neuropathy ◽  
Glycated Albumin ◽  
Creatinine Ratio ◽  
Atherosclerosis Risk In Communities ◽  
Hb A1c ◽  
Urine Albumin ◽  
Diabetes Status ◽  
Atherosclerosis Risk ◽  
Aric Study

Abstract Background The aim of this study was to assess the association of high-sensitivity cardiac troponin (hs-cTnT) and other cardiac, kidney, hyperglycemia, and inflammatory biomarkers with peripheral neuropathy (PN) in a community-based population. Methods We conducted a cross-sectional analysis of 3056 black and white participants in the Atherosclerosis Risk in Communities (ARIC) study who underwent standardized monofilament PN testing and had measures of cardiac function (hs-cTnT, N-terminal pro–B-type natriuretic peptide [NT-proBNP], and growth differentiation factor 15 [GDF15]), kidney function (serum creatinine, cystatin C, β-2 microglobulin, urine albumin-to-creatinine ratio), hyperglycemia (fasting glucose, hemoglobin A1c [Hb A1c], fructosamine, glycated albumin, 1,5-anhydroglucitol), and inflammation (C-reactive protein) assessed at visit 6 (2016–2017; age 71–94 years). We used logistic regression to assess the associations of these biomarkers (modeled in diabetes-specific tertiles) with PN in older adults with and without diabetes after adjusting for traditional risk factors. Results In total, 33.5% of participants had PN (37.3% with diabetes and 31.9% without diabetes). There was an independent association of hs-cTnT with PN regardless of diabetes status (diabetes T3 vs. T1: odds ratio [OR], 2.15 [95% CI, 1.44–3.22]; no diabetes: OR, 2.31 [95%CI, 1.76–3.03]; P = 0.72 for interaction). Among participants without diabetes, there were also significant associations of NT-proBNP (OR, 1.40 [95% CI, 1.08–1.81]) and urine albumin-to-creatinine ratio (OR, 1.55 [95% CI, 1.22–1.97]) with PN. Associations of hyperglycemia biomarkers including Hb A1c (OR, 1.76 [95% CI, 1.22–2.54]), fructosamine (OR, 1.71 [95% CI, 1.19–2.46]), and glycated albumin (OR, 1.45 [95% CI, 1.03–2.03]) with PN were significant only among participants with diabetes. Conclusions Overall, hs-cTnT appears to be a global marker of end organ damage, including PN. Laboratory biomarkers may be able to help us identify those individuals with PN.

Five-Year Stability Study of Free and Total Prostate-Specific Antigen Concentrations in Serum Specimens Collected and Stored at – 70°C or Less

2007 ◽  
Vol 22 (3) ◽  
pp. 206-213 ◽  
Author(s):  
D.A. Scaramuzzino ◽  
K. Schulte ◽  
B.N. Mack ◽  
T.F. Soriano ◽  
H.A. Fritsche
Keyword(s):  
Prostate Specific Antigen ◽  
Specific Antigen ◽  
Stability Study ◽  
Regression Analyses ◽  
Altman Analysis ◽  
Time Period ◽  
Total Prostate Specific Antigen ◽  
Deming Regression ◽  
Lower Temperature ◽  
The Stability

The stability of total (t) and free (f) prostate-specific antigen (PSA) in male serum specimens stored at –70°C or lower temperature for 4.7 to 4.9 years was studied. Until now, the stability of these analytes in serum has not been evaluated systematically beyond 2 years of storage at –70°C. Aliquots of frozen serum were thawed in 2001 and 2006 and assayed for tPSA and fPSA using a Dade Behring Dimension(r) RxL analyzer and reagents. tPSA values ranged from 0.07 to 69.94 and 0.00 to 69.83 ng/mL in 2001 and 2006, respectively, whereas fPSA values for the tested specimens ranged from 0.02 to 5.72 and 0.00 to 5.92, respectively. Deming regression analyses showed agreement in assay values over time as tPSA values yielded a slope of 1.0112 and a y-intercept of 0.0195; fPSA values produced a slope 1.0538 and a y-intercept of –0.0442; f/tPSA values yielded a slope of 0.9631 and a y-intercept of 0.1195. A Bland-Altman analysis of the data demonstrated analyte and ratio stability over this time period. We conclude that serum, when collected properly and stored at –70°C or lower temperature, may be used for tPSA and fPSA clinical studies for at least 5 years after collection.

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

2003 ◽  
Vol 8 (2) ◽  
pp. 210-215 ◽  
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)

The Periodic Impact Responses of Human-Body in a Vehicle Traveling on the Rough Terrain

2002 ◽  
Author(s):  
Ke Yu ◽  
Albert C. J. Luo
Keyword(s):  
Linear Model ◽  
Human Body ◽  
Rotational Motion ◽  
Large Mass ◽  
Rough Terrain ◽  
Lumped Mass ◽  
The Stability ◽  
Vehicle Chassis ◽  
Specific Number ◽  
Impact Motion

The human-body in a vehicle traveling on the rough terrain is modeled through the lumped mass approach and its periodic impact motions and stability are investigated through a linear model of vehicle and passenger systems. The linear model assumes the motion response of vehicle is very small compared to passenger’s rotational motion since the vehicle chassis has a very large mass and moment of inertia. The period-1 impact motion for two impacts respectively on two walls for a specific number of periods is predicted analytically and numerically. The stability and bifurcation of such a period-1 impact motion are developed analytically. The phase planes of the periodic impact motions are illustrated for a better understanding of the human-body impacting motion in the vehicle.

Fibre pulsing during melt electrospinning writing

2016 ◽  
Vol 17 (3-4) ◽  
Author(s):  
Gernot Hochleitner ◽  
Almoatazbellah Youssef ◽  
Andrei Hrynevich ◽  
Jodie N. Haigh ◽  
Tomasz Jungst ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Processing Parameters ◽  
Simple Approach ◽  
Direct Writing ◽  
Melt Electrospinning ◽  
Printing Quality ◽  
Constant Diameter ◽  
Feeding Pressure ◽  
The Stability ◽  
Acceleration Voltage

AbstractAdditive manufacturing with electrohydrodynamic direct writing is a promising approach for the production of polymeric microscale objects. In this study we investigate the stability of one such process, melt electrospinning writing, to maintain accurate placement of the deposited fibre throughout the entire print. The influence of acceleration voltage and feeding pressure on the deposited poly(ε-caprolactone) fibre homogeneity is described, and how this affects the variable lag of the jet drawn by the collector movement. Three classes of diameter instabilities were observed that led to poor printing quality: (1) temporary pulsing, (2) continuous pulsing, and (3) regular long bead defects. No breakup of the electrified jet was observed for any of the experiments. A simple approach is presented for the melt electrospinning user to evaluate fibre writing integrity, and adjust the processing parameters accordingly to achieve reproducible and constant diameter fibres.

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