scholarly journals Quantification of normetanephrine in canine urine using ELISA: evaluation of factors affecting results

2021 ◽  
pp. 104063872110529
Author(s):  
Katja Höglund ◽  
Hanna Palmqvist ◽  
Sara Ringmark ◽  
Anna Svensson
Keyword(s):  
Human Urine ◽  
Room Temperature ◽  
Plasma Catecholamines ◽  
Urine Samples ◽  
Factors Affecting ◽  
Low Concentration ◽  
Elisa Kit ◽  
Healthy Dogs ◽  
Temperature Storage ◽  
Positive Controls

Catecholamine release increases in dogs with pheochromocytomas and in situations of stress. Although plasma catecholamines degrade rapidly, their metabolites, normetanephrine (NME) and metanephrine (ME), are stable in acidified urine. Our aim was to verify a human urine ELISA kit for the quantification of NME and ME in canine urine and to determine the effects on metabolite stability of sampling time (morning or midday) and day (ordinary or day spent in a clinic). We analyzed 179 urine samples from 17 healthy dogs. For NME, the mean intra-assay CV was 6.0% for all samples and 4.3% for the canine control; inter-assay CVs were 3.3, 3.8, and 12% for high and low concentration human urine positive controls supplied in the ELISA kit and a positive canine control, respectively; spike-recovery was 90–101%. For ME, mean intra-assay CV was 6.5% for samples and 9.0% for the canine control; inter-assay CVs were 12.7, 7.2, and 22.5% for high and low concentration human urine positive controls supplied in the ELISA kit and a positive canine control, respectively; spike-recovery was 85–89%. Dilution recovery was unsatisfactory for both metabolites. Based on our verification results, NME was selected for remaining analyses. We found no effect on NME concentrations of acidification or room temperature storage for up to 24 h. The NME:creatinine ratio was higher after the first of 3 clinic days compared to the same morning (111.2 ± 5.5 vs. 82.9 ± 5.3; p < 0.0001), but not on the other days. NME verification results were generally superior to ME. Dilution studies were unsatisfactory for both metabolites. Given that NME was stable without acidification at room temperature, urine samples can be collected at home. The clinic environment can cause higher NME:creatinine ratios, especially in unaccustomed dogs.

SOLVOLYSABLE DEOXYCORTICOSTERONE CONJUGATES IN HUMAN URINE

1976 ◽  
Vol 68 (2) ◽  
pp. 273-281 ◽  
Author(s):  
C. L. COPE ◽  
S. LOIZOU
Keyword(s):  
Human Urine ◽  
Room Temperature ◽  
Urine Samples ◽  
Variable Ratio ◽  
The Mean ◽  
Sulphate Conjugate ◽  
Urine Specimens

SUMMARY The nature of the urinary conjugate converted by solvolysis, to free unconjugated deoxycorticosterone (DOC) was studied. A comparison of 11 solvolysis techniques has shown that the method employed in this study yielded 86% of the highest yield by any of the techniques tried. Three successive chromatographic systems on paper showed that no appreciable amounts of contaminants were present in the free DOC eluates, following solvolysis. By preparing authentic [3H]DOC sulphate and subjecting it to solvolysis it was shown that more than 90% of the tritiated DOC was recovered, after chromatography of the free DOC extract. This suggests that much of the solvolysable DOC in human urine is present in the form of the sulphate conjugate. The levels of DOC, excreted as the solvolysable conjugate in a variety of urine specimens, were shown to be much higher than those of free DOC, the former being 4·8 to 127 times higher than the amount of the latter. This highly variable ratio suggests that the site of production of solvolysable DOC is different from that for free DOC. The only correlation between free and solvolysable DOC was shown in dexamethasone-suppressed patients, in whom the mean percentage remaining after suppression was 30·6% for free DOC, 24·1% for solvolysable DOC and 22·2% for cortisol. As solvolysable DOC is present in much larger amounts in urine, care is necessary in the storage of urine samples in which free DOC estimates are to be made, as we found that urine specimens left at room temperature for 1 week could show rises of as much as 400% of their starting free DOC levels.

Preservation of urine free catecholamines and their free O-methylated metabolites with citric acid as an alternative to hydrochloric acid for LC-MS/MS-based analyses

2016 ◽  
Vol 54 (1) ◽  
Author(s):  
Mirko Peitzsch ◽  
Daniela Pelzel ◽  
Peter Lattke ◽  
Gabriele Siegert ◽  
Graeme Eisenhofer
Keyword(s):  
Citric Acid ◽  
Hydrochloric Acid ◽  
Room Temperature ◽  
Ethylenediaminetetraacetic Acid ◽  
Urine Samples ◽  
Alkaline Ph ◽  
Room Temperature Storage ◽  
Alkaline Urine ◽  
Liquid Chromatography Tandem Mass ◽  
Temperature Storage

AbstractMeasurements of urinary fractionated metadrenalines provide a useful screening test to diagnose phaeochromocytoma. Stability of these compounds and their parent catecholamines during and after urine collection is crucial to ensure accuracy of the measurements. Stabilisation with hydrochloric acid (HCl) can promote deconjugation of sulphate-conjugated metadrenalines, indicating a need for alternative preservatives.Urine samples with an intrinsically acidic or alkaline pH (5.5–6.9 or 7.1–8.7, respectively) were used to assess stability of free catecholamines and their free O-methylated metabolites over 7 days of room temperature storage. Stabilisation with HCl was compared with ethylenediaminetetraacetic acid/metabisulphite and monobasic citric acid. Catecholamines and metabolites were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS).Free catecholamines and their O-methylated metabolites were stable in acidic urine samples over 7 days of room temperature storage, independent of the presence or absence of any stabilisation method. In contrast, free catecholamines, but not the free O-methylated metabolites, showed rapid degradation within 24 h and continuing degradation over 7 days in urine samples with an alkaline pH. Adjustment of alkaline urine samples to a pH of 3–5 with HCl or 4.8–5.4 with citric acid completely blocked degradation of catecholamines. Ethylenediaminetetraacetic acid/metabisulphite, although reducing the extent of degradation of catecholamines in alkaline urine, was largely ineffectual as a stabiliser.Citric acid is equally effective as HCl for stabilisation of urinary free catecholamines and minimises hazards associated with use of strong inorganic acids while avoiding deconjugation of sulphate-conjugated metabolites during simultaneous LC-MS/MS measurements of free catecholamines and their free O-methylated metabolites.

scholarly journals Evaluation of an ELISA for metanephrines in feline urine

2018 ◽  
Vol 30 (6) ◽  
pp. 887-893
Author(s):  
Thanikul Srithunyarat ◽  
Anna Svensson ◽  
Sofia Hanås ◽  
Odd V. Höglund ◽  
Ragnvi Hagman ◽  
...  
Keyword(s):  
Neuroendocrine Tumors ◽  
Home Environment ◽  
Human Urine ◽  
Room Temperature ◽  
Storage Time ◽  
Stability Study ◽  
Urine Samples ◽  
Urine Sampling ◽  
The Stability ◽  
And Storage

Catecholamines can be used to evaluate neuroendocrine tumors, stress, and potentially pain, but catecholamines degrade rapidly. Their metabolites normetanephrine (NME) and metanephrine (ME) have better stability in urine. In cats, urine sampling in a home environment would be beneficial to reduce effects of clinical stress and simplify sampling. We evaluated a human urine ELISA for analysis of NME and ME in feline urine, and investigated the effects of acidification, cat tray pellets, and storage time at room temperature up to 8.5 h. In 26 feline urine samples, mean NME concentration was 192 ± 80 ng/mL, mean intra- and inter-assay CV was 6.5% and 4.2%, respectively, and spike recovery was 98–101%, but dilutional recovery was unsatisfactory. For ME, mean intra- and inter-assay CV was 10.2% and 4.1%, respectively. Mean urine ME concentration was 32.1 ± 18.3 ng/mL, close to the kit’s lowest standard, and spike recovery was 65–90%; the ELISA could not be validated for ME. The stability study, performed for NME on 12 urine samples, did not identify differences between acidified and non-acidified samples, cat tray pellets, or storage time, and no interaction effects. The ME ELISA was not suitable for feline urine; performance of the NME ELISA was acceptable, except for dilution recovery. For analysis of NME, feline urine can be sampled at home using cat tray pellets and stored at room temperature up to 8.5 h without acidification.

A fast and sensitive nanosensor based on MgO nanoparticle room-temperature ionic liquid carbon paste electrode for determination of methyldopa in pharmaceutical and patient human urine samples

Ionics ◽  
2013 ◽  
Vol 19 (12) ◽  
pp. 1907-1914 ◽  
Author(s):  
Javad Vahedi ◽  
Hassan Karimi-Maleh ◽  
Mehdi Baghayeri ◽  
Asfaneh L. Sanati ◽  
Mohammad A. Khalilzadeh ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Carbon Paste Electrode ◽  
Human Urine ◽  
Room Temperature ◽  
Urine Samples ◽  
Carbon Paste ◽  
Liquid Carbon ◽  
Paste Electrode ◽  
Mgo Nanoparticle

scholarly journals Stability of Ethanol in Blood and Urine Samples

2007 ◽  
Vol 26 (3) ◽  
pp. 241-244 ◽  
Author(s):  
Slavka Mandić-Radić ◽  
Gordana Džingalašević ◽  
Nevena Luković
Keyword(s):  
Whole Blood ◽  
Room Temperature ◽  
Urine Samples ◽  
Time Intervals ◽  
Blood Samples ◽  
Duration Of Storage ◽  
Different Temperatures ◽  
Blood And Urine Samples ◽  
Excessive Alcohol ◽  
Temperature Storage

Stability of Ethanol in Blood and Urine SamplesThe changes of ethanol concentrations in whole blood and urine samples were analyzed depending on temperatures and duration of storage. The aim of the study was to establish standards for the Institute laboratory. Samples of whole blood and urine, taken from drivers with excessive alcohol concentrations (6 groups, 15 samples per each), were analyzed upon delivery and then after storage during different time intervals and at different temperatures. The results showed that alcohol concentrations were significantly reduced with the increase of temperature and prolongation of storage. Only the whole blood samples stored for up to one month at -20 °C did not show significant changes. Room temperature storage of samples is the least suitable way of keeping them, independently of the duration of storage. Urines are not less reliable samples than blood. There are no ethanol differences between blood samples with and without sodium fluoride.

THE STUDY ON TA VAT WINE PRODUCTION FROM SUGAR PALM (ARENGA PINNATA) SAP

2014 ◽  
Vol 83 (5) ◽  
Author(s):  
Nguyễn Thị Hồng Thu ◽  
Đặng Minh Nhật ◽  
Nguyễn Hoàng Dung
Keyword(s):  
Room Temperature ◽  
Fermentation Process ◽  
Inoculum Size ◽  
Wine Fermentation ◽  
Wine Production ◽  
Factors Affecting ◽  
Natural Fermentation ◽  
Tropical Asia ◽  
Best Parameters

Sugar palm (Arenga pinnata) is a feather palm native to tropical Asia. In Vietnam, it is named Búng Báng or Đoác and grown only on the highlands in the central or northern part of Vietnam. It is utilized for many purposes, especially for Ta Vat wine production - a characteristic and unique product of Co Tu ethnic minority. However, because of the natural fermentation used in the production, the product quality is inconsistent. The purpose of this study was to examine a new procedure of using palm sap for making Ta Vat wine. Some characteristics of the sap, which was collected at Nam Giang district, Quang Nam province are determined, proving the potential of the sap for making wine product. The quality of sap changes quickly at room temperature. At low temperature (4 - 60C), the changes in sap quality are apparently slower. Examining some factors affecting its quality during the wine fermentation process, we determined the best parameters for the fermentation process as follows: inoculum size of 3% with cell density of about 1x108 cells/ml, the addition of the extract from the bark of Ceylon ironwood (Mesua ferrea L.) 4%. Keywords: Arenga pinnata, sap, Ceylon ironwood bark, Mesua ferrea L., wine fermentation.

The influence of taurine and L-carnitine on 6 β-hydroxycortisol/cortisol ratio in human urine of healthy volunteers

2019 ◽  
Vol 34 (3) ◽  
Author(s):  
Anna A. Makhova ◽  
Eugenia V. Shikh ◽  
Tatiana V. Bulko ◽  
Zhanna M. Sizova ◽  
Victoria V. Shumyantseva
Keyword(s):  
Catalytic Activity ◽  
Healthy Volunteers ◽  
Human Urine ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Metabolic Ratio ◽  
Urine Samples ◽  
Cyp3a4 Activity ◽  
Active Compounds ◽  
Cortisol Ratio

Abstract Background Cytochrome P450s (CYPs, EC 1.14.14.1) are the main enzymes of drug metabolism. The functional significance of CYPs also includes the metabolism of foreign chemicals and endogenic biologically active compounds. The CYP3A4 isoform contributes to the metabolism of about half of all marketed medicinal preparations. The aim of this study was to investigate the effects of two biologically active compounds: 2-aminoethane-sulfonic acid (taurine) and 3-hydroxy-4-trimethylaminobutyrate (L-carnitine) on urinary 6β-hydroxycortisol/cortisol (6β-OHC/cortisol) metabolic ratio as a biomarker of the CYP3A4 activity of healthy volunteers. Taurine is used for the treatment of chronic heart failure and liver disease. Cardiologists, nephrologists, neurologists, gerontologists in addition to the main etiopathogenetic therapies, use L-carnitine. The quantification of the 6β-OHC/cortisol metabolic ratio as a biomarker of CYP3A4 activity in human urine was used for the assessment of CYP3A4 catalytic activity as a non-invasive test. Methods The study included 18 healthy male volunteers (aged from 18 to 35 years old). The volunteers took taurine in a dose of 500 mg twice a day or L-carnitine in a dose of 2.5 mL 3 times a day for 14 consecutive days. The test drug was given 20 min before meals. The collection of urine samples was performed before and after 3, 7, 10, and 14 days after taurine intake. The metabolic ratio of 6β-OHC/cortisol in morning spot urine samples was studied by the liquid chromatography/mass spectroscopy (LC/MS) method. Results The ratio of 6-6β-OHC/cortisol was used as a biomarker to study the taurine and L-carnitine influence on CYP3A4 metabolism of cortisol. The ratio of urinary 6β-OCH/cortisol in the morning urine samples of volunteers before the beginning of taurine therapy (baseline ratio) was 2.71 ± 0.2. Seven days after the administration of taurine in a dose of 500 mg twice a day, the 6β-OCH/cortisol ratio was 3.3 ± 0.2, which indicated the increased catalytic activity of CYP3A4 towards cortisol. As for the L-carnitine supplementation, analysis of the 6β-OCH/cortisol ratio in the urine for 14 days did not show any significant changes in this baseline ratio, indicating the lack of L-carnitine influence on the catalytic activity of CYP3A4 to cortisol. Conclusions The results obtained demonstrated the influence of taurine on 6β-OCH/cortisol metabolic ratio as a biomarker of CYP3A4 catalytic activity to cortisol. L-carnitine did not affect the activity of CYP3A4. The lack of a clinically meaningful effect of L-carnitine was established.

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