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2. Deconjugated urinary metanephrine, normetanephrine and 3-methoxytyramine in laboratory diagnosis of pheochromocytoma and paraganglioma

Creator:
Radovan Bílek, Tomáš Zelinka, Petr Vlček, Jaroslava Dušková, David Michalský, Novák, K., Jiří Bešťák, and Jiří Widimský
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, moč, chromatografie, feochromocytomy, paragangliomy, urine, chromatography, pheochromocytoms, paraganglioms, deconjugated metanephrine, deconjugated normetanephrine, deconjugated 3-methoxytyramine, electrochemical detection, 14, and 612
Language:
English
Description:
This work discusses the clinical performance of deconjugated metanephrine (MN), normetanephrine (NMN) and 3-methoxytyramine (3MT) determined in the basal first morning urine using a chromatographic method with electrochemical detection for the clinical diagnosis of pheochromocytoma (PHEO) and paraganglioma (PGL). Urine samples were collected from 44 patients (36 with PHEO, 8 with PGL) aged 54+/-17 (20-78) years (22 females, 22 males). A sampling of biological materials was performed preoperatively and about one week, six months and one year after adrenal gland surgery. The control group consisted of 34 PHEO/PGL patients more than 4 months after adrenal gland surgery. All subjects in the control group were without a diagnosis of PHEO or PGL. Clinical sensitivity was 55 % for MN, 64 % for NMN, 80 % for combination of both MN and NMN, and only 23 % for 3TM. Clinical specificity calculated from the control group was 93 % for MN, 95 % for NMN, 95 % for the combination MN and NMN, and 97 % for 3TM. Cut-off values for deconjugated metanephrines in the basal urine were 310 (MN), 690 (NMN) and 250 μg/l (3MT). Chromatographic determination of deconjugated urinary metanephrines, which is simple without the necessity of special laboratory material, can serve for the screening of PHEO or PGL patients. Urine NMN and 3MT exerts an association to malignity, and all markers are associated with tumor mass. However, the principal laboratory diagnosis of PHEO or PGL must be based on plasma-free metanephrines and plasma chromogranin A with better performance in the laboratory diagnosis of PHEO or PGL., R. Bílek, T. Zelinka, P. Vlček, J. Dušková, D. Michalský, K. novák, J. Bešťák, J. Widimský Jr., and Obsahuje bibliografii
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

3. Hypertension in spontaneously hypertensive rats occurs despite low plasma levels of homocysteine

Creator:
Kondziella, Daniel, Zetterberg, H., Haugen, E., and Fu, M.
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, neurochemie, aminokyseliny, argininamid, homocystein, hypertenze, chromatografie, oxid dusnatý, neurochemistry, amino acids, homocysteine, hypertension, chromatography, nitric oxide, citrulline, ion exchange chromatography, ornithine, spontaneously hypertensive rats (SHR), 14, and 612
Language:
English
Description:
Hyperhomocysteinemia has been suggested to induce hypertension due to its role in endothelial dysfunction. However, it remains controversial whether homocysteine and hypertension are truly causally related or merely loosely associated. To test the hypothesis that hyperhomocysteinemia occurs in spontaneously hypertensive rats (SHR) we measured plasma levels of homocysteine in 10 male adult SHR and in 10 normotensive controls using ion exchange chromatography. In addition, plasma concentrations of the 22 most common amino acids were measured to explore the relation of homocysteine with amino acid metabolism. Plasma levels of homocysteine were significantly lower in SHR (4.1±0.1 μmol/l) than in controls (7.2±0.3 μmol/l) (p<0.00001). The amounts of aminobutyric acid, alanine, citrulline and valine were also decreased, whereas we found increased levels of aspartate, glutamate, glutamine, histidine and ornithine. Thus, contrary to our hypothesis, hypertension in SHR occurs despite low plasma levels of homocysteine. We provide a new hypothesis whereby reduced conversion of arginine to citrulline is related to increased ornithine levels, but decreased bioavailability of nitric oxide, resulting in impaired blood vessel relaxation and hypertension. In conclusion, our findings do not necessarily exclude that homocysteine and hypertension might be pathophysiologically connected, but corroborate the notion that hypertension can arise due to mechanisms independent of high homocysteine levels., D. Kondziella, H. Zetterberg, E. Haugen, M. Fu., and Obsahuje bibliografii a bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public