Reply to comments on ‘An HPLC method for the measurement of free cortisol/cortisone ratio in human urine’

2007 ◽  
Vol 21 (11) ◽  
pp. 1222-1222
Author(s):  
Al Sharef O ◽  
Feely J ◽  
Scott KR ◽  
Kavanagh PV ◽  
Sharma SC
2007 ◽  
Vol 21 (11) ◽  
pp. 1201-1206 ◽  
Author(s):  
O. Al Sharef ◽  
J. Feely ◽  
P. V. Kavanagh ◽  
K. R. Scott ◽  
S. C. Sharma

Separations ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 226
Author(s):  
Matteo Chiarello ◽  
Laura Anfossi ◽  
Simone Cavalera ◽  
Fabio Di Di Nardo ◽  
Thea Serra ◽  
...  

NanoMIPs that are prepared by solid phase synthesis have proven to be very versatile, but to date only limited attention has been paid to their use in solid phase extraction. Thus, since nanoMIPs show close similarities, in terms of binding behavior, to antibodies, it seems relevant to verify if it is possible to use them as mimics of the natural antibodies that are used in immunoextraction methods. As a proof-of-concept, we considered prepared nanoMIPs against fluoroquinolone ciprofloxacin. Several nanoMIPs were prepared in water with polymerization mixtures of different compositions. The polymer with the highest affinity towards ciprofloxacin was then grafted onto a solid support and used to set up a solid phase extraction–HPLC method with fluorescence detection, for the determination of fluoroquinolones in human urine. The method resulted in successful selection for the fluoroquinolone antibiotics, such that the nanoMIPs were suitable for direct extraction of the antibiotics from the urine samples at the µg mL−1 level. They required no preliminary treatment, except for a 1 + 9 (v/v) dilution with a buffer of pH 4.5 and they had good analyte recovery rates; up to 85% with precision in the range of 3 to 4.5%, without interference from the matrix. These experimental results demonstrate, for the first time, the feasibility of the use of nanoMIPs to develop solid phase extraction methods.


2005 ◽  
Vol 51 (2) ◽  
pp. 408-415 ◽  
Author(s):  
Grazyna Chwatko ◽  
Hieronim Jakubowski

Abstract Background: A metabolite of homocysteine (Hcy), the thioester Hcy-thiolactone, has been implicated in coronary heart disease in humans. Because inadvertent reactions of Hcy-thiolactone with proteins can lead to cell and tissue damage, the ability to detoxify or eliminate Hcy-thiolactone is essential for biological integrity. We examined the hypothesis that the human body eliminates Hcy-thiolactone by urinary excretion. Methods: We used a sensitive HPLC method with postcolumn derivatization and fluorescence detection to examine Hcy-thiolactone concentrations in human urine and plasma. Results: We discovered a previously unknown pool of Hcy-thiolactone in human urine. Urinary concentrations of Hcy-thiolactone (11–485 nmol/L; n = 19) were ∼100-fold higher than those in plasma (<0.1–22.6 nmol/L; n = 20). Urinary Hcy-thiolactone accounted for 2.5–28.3% of urinary total Hcy, whereas plasma Hcy-thiolactone accounted for <0.002–0.29% of plasma total Hcy. Urinary concentrations of Hcy-thiolactone, but not of total Hcy, were negatively correlated with urinary pH. Clearance of Hcy-thiolactone, relative to creatinine, was 0.21–6.96. In contrast, relative clearance of Hcy was 0.001–0.003. Conclusions: The analytical methods described here can be used to quantify Hcy-thiolactone in biological fluids. Using these methods we showed that the human body eliminates Hcy-thiolactone by urinary excretion. Our data also suggest that the protonation status of its amino group affects Hcy-thiolactone excretion.


2007 ◽  
Vol 21 (5) ◽  
pp. 480-483 ◽  
Author(s):  
Zhi-Yong Guo ◽  
Dan-Yi Wei ◽  
Yuan-Yuan Wang ◽  
Kun-Fei Xuan ◽  
Xu-Fei Yu ◽  
...  

2003 ◽  
Vol 378 (2) ◽  
pp. 536-543 ◽  
Author(s):  
I. Šperlingová ◽  
L. Dabrowská ◽  
V. Stránský ◽  
M. Tichý

2020 ◽  
Vol 65 (7) ◽  
pp. 418-423
Author(s):  
Z. R. Shafigullina ◽  
L. I. Velikanova ◽  
N. V. Vorokhobina ◽  
E. V. Malevanaya ◽  
E. G. Strelnikova ◽  
...  

Immunochemical methods of analysis are traditionally used for diagnosis of various forms of Cushing’s syndrome (CS). In the presence of boundary values of hormonal parameters, doubtful situations, a combination of changes both in pituitary and in adrenal glands, it is useful to determine additional differential diagnostic criteria for the diagnosis of various forms of CS. Urinary steroid profiles (USP) were analyzed by gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) for 38 females with adrenal Cushing’s syndrome (CSA), 42 females with pituitary CS (CSP) and 25 healthy females (control group). An increase of free cortisol/free cortisone ratio in the urine (UFF/UFE) for CSP patients in comparison of CSA was obtained by HPLC method. Decreased urinary excretion of UFF and UFE by more than 60% after the 8 mg dexamethasone suppression test had 100% sensitivity and specificity of more than 90% for the diagnosis of CSP. GC-MS method in patients with CSA and CSG revealed the peculiarities of androgens, progestins and glucocorticoids metabolism which leaded to obtain specific USP for CS of different genesis. Increased urinary excretions of dehydroepiandrosterone and its metabolites, metabolites of androstenedione, the ratio of sum of cortisol and cortisone tetrahydrometabolites to tetrahydro-11-deoxycortisol (more then 36) in CSP patients compared with CSA are additional signs for differential diagnosis of these diseases. The combination of classical tests and USP obtained by HPLC and GC-MS methods increased the sensitivity and specificity of differential diagnosis of CSA and CSP.


1997 ◽  
Vol 43 (8) ◽  
pp. 1386-1391 ◽  
Author(s):  
Ursula Turpeinen ◽  
Helene Markkanen ◽  
Matti Välimäki ◽  
Ulf-Håkan Stenman

Abstract We here report a reversed-phase HPLC method for the determination of free cortisol in human urine, using methylprednisolone as the internal standard. Before chromatography, samples were extracted with a C18 solid-phase extraction column and the steroids were separated on a LiChrospher 100 C18 column with a mobile phase of methanol/acetonitrile/water (43/3/54 by vol). Linearity, precision, and accuracy of the method were established. The detection limit was 10 pmol of cortisol, and total CVs were <8%. With various solid-phase extraction columns the recovery of cortisol was 36–97%; recovery of the internal standard was 43–85%. Study of interference by 6 other steroids and metabolites and 24 drugs showed that carbamazepine and digoxin partly overlapped with cortisol, but this interference could be reduced by modification of the mobile phase. The HPLC method was compared with an RIA and an automated immunoassay method. The results obtained by HPLC averaged 40% of the RIA values.


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