-SHp Test

The -SHp Test is used to determine photometrically in the blood the concentration of thiols.

Thiols, organic compounds characterized by having in their molecule a sulfhydryl Group (-SH), represent a significant qualitative component of the plasma antioxidant barrier against free radicals. Some of its component are cysteine (isolated or incorporated into peptides, such as glutathione, but also direct proteins) and lipoic acid.

Principle

Sulphydryl groups of molecules of plasma components (such as protein, P-SH) may object to the phase of propagation of processes both alkoxy radicals inactivating peroxidative activity (RO) that hydroxyl (I).
-SHp Test is based on the ability of the groups – SH to develop a colored complex can be determined photometrically when they react with a special acid (DTNB) according to the method first proposed by Ellman in 1959 and then adapted by Carratelli. The "title" of thiols is directly proportional to the intensity of detected color instrumentally.

Working conditions

–SHp Test must be carried on fresh serum or plasma.
It can be performed both with the dedicated systems (FREE CarpeDiem or FREE Duo) and with standard manual photometers. On the basis of the published data the -SHp Test is a reliable, accurate and repeatable test.

Reference Values

Range in healthy subjects is between 450 and 650 μmol/L. Lower values correlates directly with a reduced efficiency of thiol anti-oxidant barrier. Values lower than 450 µmol/L indicate an impairment of the thiol component of antioxidant plasma barrier and suggest, therefore, an oxidative stress condition. Such condition, however, should be confirmed by carrying out other specific tests (e. g. d-ROMs test, OXY-Adsorbent test, and BAP test).

Clinical studies

The –SHp Test proven to be reliable for the determination of the thiol component of the antioxidant plasma barrier in many clinical studies, supporting the results of the OXY-Adsorbent Test and d-ROMs Test in the global evaluation of oxidative stress, particularly in smokers, patients with kidney transplant, dialised, uremics and to monitor the efficacy of integration in cancer patients.
Particularly interesting also the results in veterinary medicine, for example with bovines.
-SHp Test, moreover, is particularly indicated when you have a suspect of an oxidative stress situation and d-ROMs values are low. Such a situation can happen, for example, with solid tumors. In these case, the shift of the cellular metabolism from aerobic to anaerobic follows the production, around the tumoral mass, of acid catabolites. These, reducing locally the pH, can facilitate the release of iron, a catalyst for the formation of alcoxyl radical from circulating hydroperoxides. Thiol groups, then, can react with alcoxyl radicals reducing, in fact, the level of hydroperoxides. In this case, the d-ROMs Test will exhibit low values not because there isn’t a production of hydroperoxides, but because they are neutralized by sulfidric group. This specific clinical situation can be assessed only by a low value of the -SHp Test together with low values of d-ROMs.

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