Aspects physico-chimiques des espèces réactives de l’oxygène

Oxidative stress in chronic lymphocytic leukemia: still a matter of debate

There is a large body of evidence showing a strong correlation between carcinogenesis of several types of human tumors, including chronic lymphocytic leukemia (CLL), and oxidative stress (OS). The mechanisms by which OS may promote cancer pathogenesis have not been completely deciphered yet and, in CLL, as in other neoplasms, whether OS is a primary cause or simply a downstream effect of the disease is still an open question. It has been demonstrated that, in CLL, OS concomitantly results from increased reactive oxygen species (ROS) production, mainly ascribable to CLL cells mitochondrial activity, and impaired antioxidant defenses. Interestingly, OS evaluation in CLL patients, at diagnosis, seems to have a prognostic significance, thus getting new insights in the biological comprehension of the disease with potential therapeutic implications.

Prognostic relevance of oxidative stress measurement in chronic lymphocytic leukaemia

OBJECTIVE

To evaluate the prognostic significance of oxidative stress (OS) and antioxidant defence status measurement in patients with chronic lymphocytic leukaemia (CLL).

METHODS

d-ROMs test and BAP test were evaluated at diagnosis of 165 patients with CLL and correlated with clinical-biological features and prognosis.

RESULTS

An increased oxidative damage (d-ROMs test) and a reduced antioxidant potential (BAP test) were found in CLL patients than normal controls (P<.0001). CLL patients with higher d-ROMs values had higher number of circulating white blood cells and lymphocytes, and higher values of β₂ -microglobulin. Higher d-ROMs values were found in female (P=.0003), in patients with unmutated IgVH (P=.04), unfavourable cytogenetics (P=.002) and more advanced clinical stage (P=.002). Higher BAP test values were found in patients expressing CD49d (P=.01) and with more advanced clinical stage (P=.004). At a median follow-up of 48 months, CLL patients with d-ROMs ≥418 CARR U were found to have a shorter time to first treatment (TFT) (P=.0002), and a reduced survival (P=.006) than others. CLL patients with BAP test values ≥2155 μmol/L had a shorter TFT (P=.008) and a shorter survival (P=.003).

CONCLUSIONS

OS can affect CLL patients by concomitantly increasing reactive oxygen metabolites production and decreasing antioxidant defences.

Hypobromous acid, a powerful endogenous electrophile: Experimental and theoretical studies

Hypobromous acid (HOBr) is an inorganic acid produced by the oxidation of the bromide anion (Br(-)). The blood plasma level of Br(-) is more than 1,000-fold lower than that of chloride anion (Cl(-)). Consequently, the endogenous production of HOBr is also lower compared to hypochlorous acid (HOCl). Nevertheless, there is much evidence of the deleterious effects of HOBr. From these data, we hypothesized that the reactivity of HOBr could be better associated with its electrophilic strength. Our hypothesis was confirmed, since HOBr was significantly more reactive than HOCl when the oxidability of the studied compounds was not relevant. For instance: anisole (HOBr, k2=2.3×10(2)M(-1)s(-1), HOCl non-reactive); dansylglycine (HOBr, k2=7.3×10(6)M(-1)s(-1), HOCl, 5.2×10(2)M(-1)s(-1)); salicylic acid (HOBr, k2=4.0×10(4)M(-1)s(-1), non-reactive); 3-hydroxybenzoic acid (HOBr, k2=5.9×10(4)M(-1)s(-1), HOCl, k2=1.1×10(1)M(-1)s(-1)); uridine (HOBr, k2=1.3×10(3)M(-1)s(-1), HOCl non-reactive). The compounds 4-bromoanisole and 5-bromouridine were identified as the products of the reactions between HOBr and anisole or uridine, respectively, i.e. typical products of electrophilic substitutions. Together, these results show that, rather than an oxidant, HOBr is a powerful electrophilic reactant. This chemical property was theoretically confirmed by measuring the positive Mulliken and ChelpG charges upon bromine and chlorine. In conclusion, the high electrophilicity of HOBr could be behind its well-established deleterious effects. We propose that HOBr is the most powerful endogenous electrophile.

[Solutions for organ preservation and other cardioplegic liquid formulations. Role of the hospital pharmacist]

Solid organ transplantation is an increasing need and a well-established activity which requires maintaining the quality of the transplant from procurement through the entire, storage, transport and graft procedure. Solutions for organ preservation play a key role in this procedure, by minimizing the deleterious effects of both ischemia and reperfusion. As such, their qualitative and quantitative compositions have to be optimized and validated. The development strategy and formulations proposed for these solutions are analyzed in this review as well as the results of the clinical studies which have set up the relevant pharmacological and physicochemical criteria. The French regulatory status of these products is also discussed. A clear distinction has to be made between solutions for organ preservation which are classified as produits thérapeutiques annexes (therapeutic ancillary products) and cardioplegic liquid formulations which are considered as medicinal products and are subject to marketing approval. Finally, the roles of the hospital pharmacist in the evaluation, selection, purchase and proper use of these products are described.