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.

Homogeneous enzyme immunoassay for tobramycin evaluated and compared with a radioimmunoassay.

1982 ◽  
Vol 28 (6) ◽  
pp. 1370-1374 ◽  
Author(s):  
J Woo ◽  
M A Longley ◽  
D C Cannon
Keyword(s):  
Enzyme Immunoassay ◽  
Room Temperature ◽  
Correlation Study ◽  
Stability Study ◽  
Data Handling ◽  
Handling System ◽  
Analytical Recovery ◽  
Assay Precision ◽  
Absorbance Data ◽  
Homogeneous Enzyme Immunoassay

Abstract We evaluated a commercially available homogeneous enzyme immunoassay (EMIT, Syva Co.) for tobramycin against a reference radioimmunoassay (RIA) method. Between-assay precision (CV) was 2.9% at 6.2 mg/L and 3.0% for values in the range of 1.0-7.6 mg/L. Accuracy based on a recovery experiment (1.0-13.0 mg/L) yielded an analytical recovery of 88-112%. A correlation study with 75 sera from patients on tobramycin therapy showed that EMIT = 0.984 RIA - 0.0808, r = 0.993. Neither the EMIT nor the RIA procedure was affected by the presence of gentamicin, amikacin, and vancomycin. Absorbance data from the EMIT system calculated with the conventional RIA logit-log algorithm correlate well with results generated by the Syva data-handling system (logit-log = 1.077 Syva - 0.318, r = 0.998). A reagent stability study indicated that the EMIT reagents, once reconstituted, remain stable for at least 17 days when stored at refrigerated temperatures, or 11 days if stored at room temperature, thus enabling frequent "stat" assays without the need to prepare a calibration curve each time.

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.

scholarly journals Preanalytical Sample Handling Conditions and Their Effects on the Human Serum Metabolome in Epidemiologic Studies

2020 ◽  
Author(s):  
Kathleen M McClain ◽  
Steven C Moore ◽  
Joshua N Sampson ◽  
Theresa R Henderson ◽  
Sarah K Gebauer ◽  
...  
Keyword(s):  
False Positive ◽  
Room Temperature ◽  
Epidemiologic Studies ◽  
Clotting Time ◽  
Serum Samples ◽  
Sample Handling ◽  
Nutrition Research ◽  
Human Nutrition Research ◽  
The Us ◽  
Case Status

Abstract Many epidemiologic studies use metabolomics for discovery-based research. The degree to which sample handling may influence findings, however, is poorly understood. In 2016, serum samples from 13 volunteers from the US Department of Agriculture’s Beltsville Human Nutrition Research Center were subjected to different clotting (30 minutes/120 minutes) and refrigeration (0 minutes/24 hours) conditions, as well as different numbers (0/1/4) and temperatures (ice/refrigerator/room temperature) of thaws. The median absolute percent difference (APD) between metabolite levels and correlations between levels across conditions were estimated for 628 metabolites. The potential for handling artifacts to induce false-positive associations was estimated using variable hypothetical scenarios in which 1%–100% of case samples had different handling than control samples. All handling conditions influenced metabolite levels. Across metabolites, the median APD when extending clotting time was 9.08%. When increasing the number of thaws from 0 to 4, the median APD was 10.05% for ice and 5.54% for room temperature. Metabolite levels were correlated highly across conditions (all r’s ≥ 0.84), indicating that relative ranks were preserved. However, if handling varied even modestly by case status, our hypotheticals showed that results can be biased and can result in false-positive findings. Sample handling affects levels of metabolites, and special care should be taken to minimize effects. Shorter room-temperature thaws should be preferred over longer ice thaws, and handling should be meticulously matched by case status.

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.

Protein A-sepharose used to measure free insulin in plasma

1991 ◽  
Vol 37 (1) ◽  
pp. 64-67 ◽  
Author(s):  
Didler Chevenne ◽  
Franclne Valade ◽  
Marle-Pascal Bridel ◽  
Odlie Rigal ◽  
Jean-Francols Demelier ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Insulin Therapy ◽  
Binding Capacity ◽  
Protein A ◽  
Insulin Antibodies ◽  
New Method ◽  
Diabetic Patients ◽  
Insulin In Plasma ◽  
Free Insulin

Abstract Diabetic patients receiving insulin therapy generally develop anti-insulin antibodies that must be eliminated, usually by extraction with polyethylene glycol (PEG), before determining the concentration of free (active) insulin in plasma. We describe a new method for removing such antibodies, with the use of Protein A coupled to Sepharose microspheres. The results correlate well with those by the PEG method, although values are systematically higher or lower for given samples, according to the initial titer of the antibody measured in terms of binding capacity. Further studies are required to clarify this observation.

Investigations on the Nature of Hemophilia A

1963 ◽  
Vol 09 (01) ◽  
pp. 030-052 ◽  
Author(s):  
Eberhard Mammen
Keyword(s):  
Factor Viii ◽  
Human Plasma ◽  
Barium Sulfate ◽  
Freeze Drying ◽  
Room Temperature ◽  
Hemophilia A ◽  
Normal Human Plasma ◽  
Normal Human ◽  
And Storage ◽  
Prothrombin Activation

SummaryIn this paper an inhibitor is described that is found in hemophilic plasma and serum different from any till now described inhibitor. The inhibitor only inhibits prothrombin activation in the “intrinsic clotting systems”. This inhibitor is probably not present in normal human plasma or serum. It is destroyed by ether and freeze drying, is labile to acid and storage at room temperature. It is stable upon dialysis and has not been adsorbed on barium sulfate, aluminum hydroxide or kaolin. It precipitates at 50% v/v saturation with alcohol. The nature of this inhibitor seems to be a protein or lipoprotein.Factor VIII was isolated from hemophilic plasma. The amount isolated was the same as from normal plasma and the activity properties were not different. Hemophiliacs have normal amounts of factor VIII.

Seed-mediated synthesis and PEG coating of gold nanoparticles for controlling morphology and sizes

MRS Advances ◽  
2020 ◽  
Vol 5 (63) ◽  
pp. 3353-3360
Author(s):  
Susana Helena Arellano Ramírez ◽  
Perla García Casillas ◽  
Christian Chapa González
Keyword(s):  
Gold Nanoparticles ◽  
Polyethylene Glycol ◽  
Room Temperature ◽  
Colloidal Stability ◽  
Infrared Spectrometry ◽  
Ammonium Bromide ◽  
Chloroauric Acid ◽  
Vis Spectroscopy ◽  
Seed Mediated ◽  
Peg Coating

AbstractA significant area of research is biomedical applications of nanoparticles which involves efforts to control the physicochemical properties through simple and scalable processes. Gold nanoparticles have received considerable attention due to their unique properties that they exhibit based on their morphology. Gold nanospheres (AuNSs) and nanorods (AuNRs) were prepared with a seed-mediated method followed of polyethylene glycol (PEG)-coating. The seeds were prepared with 0.1 M cetyltrimethyl-ammonium bromide (CTAB), 0.005 M chloroauric acid (HAuCl4), and 0.01 M sodium borohydride (NaBH4) solution. Gold nanoparticles with spherical morphology was achieved by growth by aggregation at room temperature, while to achieve the rod morphology 0.1 M silver nitrate (AgNO3) and 0.1 M ascorbic acid solution were added. The gold nanoparticles obtained by the seed-mediated synthesis have spherical or rod shapes, depending on the experimental conditions, and a uniform particle size. Surface functionalization was developed using polyethylene glycol. Morphology, and size distribution of AuNPs were evaluated by Field Emission Scanning Electron Microscopy. The average size of AuNSs, and AuNRs was 7.85nm and 7.96 x 31.47nm respectively. Fourier transform infrared spectrometry was performed to corroborate the presence of PEG in the AuNPs surface. Additionally, suspensions of AuNSs and AuNRs were evaluated by UV-Vis spectroscopy. Gold nanoparticles were stored for several days at room temperature and it was observed that the colloidal stability increased once gold nanoparticles were coated with PEG due to the shield formed in the surface of the NPs and the increase in size which were 9.65±1.90 nm of diameter for AuNSs and for AuNRs were 29.03±5.88 and 8.39±1.02 nm for length and transverse axis, respectively.

Polyethylene glycol/modified carbon foam composites for efficient light-thermal conversion and storage

Polymer ◽  
2021 ◽  
pp. 123894
Author(s):  
Fankai Lin ◽  
Xiaoguang Zhang ◽  
Xianjie Liu ◽  
Yunfei Xu ◽  
Zhenhua Sun ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Carbon Foam ◽  
Thermal Conversion ◽  
And Storage

scholarly journals Evaluation of Microbial Culture Techniques for the Isolation of Pythium Insidiosum from Equine Tissues

2002 ◽  
Vol 14 (4) ◽  
pp. 288-294 ◽  
Author(s):  
Amy M. Grooters ◽  
Amy Whittington ◽  
Mae K. Lopez ◽  
Michelle N. Boroughs ◽  
Alma F. Roy
Keyword(s):  
Room Temperature ◽  
Microbial Culture ◽  
Sample Type ◽  
Pythium Insidiosum ◽  
Selective Media ◽  
Culture Techniques ◽  
Media Type ◽  
Antibiotic Solution ◽  
And Storage ◽  
Storage Technique

The purpose of this study was to evaluate the effects of sample handling, storage, and culture techniques on the isolation of Pythium insidiosum from infected equine tissues. Tissue and kunker samples obtained immediately posteuthanasia from a horse with subcutaneous pythiosis were used to assess the effects of sample type (kunkers vs. tissues), media type (selective vs. nonselective), storage technique, and storage time on P. insidiosum isolation rate. Overall, isolation rates were higher from fresh kunkers (94.6%) and stored kunkers (76.4%) than from fresh tissues (8.3%) or stored tissues (4.6%). Isolation of P. insidiosum also occurred more often on antibiotic-containing media than on nonselective media for both fresh and stored samples. For samples that were stored for 1–3 days prior to culture, P. insidiosum isolation rates were highest for the following techniques: kunkers stored at room temperature and plated on selective media (100%), kunkers stored at 4 C and then plated on either nonselective (91.7%) or selective (95.8%) media, kunkers stored on cold packs and then plated on either nonselective (93.8%) or selective (100%) media, kunkers stored in ampicillin solution and plated on selective media (100%), and kunkers stored in ampicillin/gentocin solution and plated on selective media (87.5%). For samples stored for 4–5 days, P. insidiosum isolation rates were highest for kunkers stored at 4 C and then plated on either nonselective (81.3%) or selective (87.5%) media, kunkers stored in ampicillin solution and then plated on selective media (87.5%), and kunkers stored in ampicillin/gentocin solution and plated on selective media (87.5%). Results of this study suggest that optimal isolation rates of P. insidiosum from infected equine tissues are achieved by culturing fresh kunkers on selective media. For samples that cannot be processed immediately, acceptable handling techniques include storage at room temperature for up to 3 days, refrigeration for up to 5 days, shipping on cold packs, and storage in antibiotic solution, each combined with subsequent inoculation on selective media.

DEVELOPMENT OF CITRUS BASED BEVERAGE UTILIZING BACOPA MONNIERI

2021 ◽  
pp. 18-19
Author(s):  
Twamoghna De ◽  
Purushottam Kumar ◽  
Jayati Pal
Keyword(s):  
Sensory Evaluation ◽  
Room Temperature ◽  
Control Sample ◽  
Leaf Extracts ◽  
Nutritional Values ◽  
Soda Water ◽  
Three Samples ◽  
Microbial Analysis ◽  
And Storage

The study was done to formulate a drink from an old medicinal herb and retain all the potential benets with a new taste and avor. For this an herbal drink was formulated and its quality ascertained. In the rst part of the study, syrup was prepared from the raw leaves of the herb with addition of acids and avors. Then this syrup was diluted further followed by carbonation with 1:3 ratio of soda water and bottled. Three samples were prepared namely, T1 (same as previous but with 1:3 ratio carbonation and dividing the sample hot lled and cold lled ). In the next part, prepared samples were subjected to sensory evaluation,chemical and microbial analysis when fresh and 0 after regular intervals at room temperature (27±1 °C) and refrigerated temperature (below 7 C). Microbial analysis of the product was done to check the quality of the herbal drink and self-life of the product. The control sample T1 cold lled was the most acceptable due to its unique taste and avor, followed by sample T1( hot lled) . The present study entailed to conclude that preparation of a drink with B. monnieri leaf extracts gives a new taste and avor with high nutritional values. This drink can be stored safe for nearly a month if carbonated and storage at refrigerated 0 temperature (below 5 C).

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