Towards harmonization of solutions used for cystic fibrosis diagnosis by nasal potential difference measurements: A formulation approach with CHESS® software.

BACKGROUND: One diagnosis of cystic fibrosis involves measuring the nasal transepithelial potential difference (NPD) as a complementary technique in the forms of the disease, where the sweat test is non-discriminating. The NPD is measured using solutions with and without chlorides, containing a variety of substances whose activities on nasal mucus membranes are studied or assessed. Among the solutions described in the literature and used in specialized centers, none seems to be best adapted for industrial production for reasons of stability (formulas of the international consensus of Rowe et al. and formulas of Knowles et al.) and/or potential toxicity (formulas of Middleton et al.). OBJECTIVE(S): Defining new formulas, according to those of the international consensus, with greater physicochemical and microbiological stability. METHODS: The reformulation tests were conducted on the formulas of Rowe et al., using CHESS® (CHemical Equilibrium of Species and Surfaces) software for modeling aqueous systems that substantially reduced the number of experiments. CHESS® software was first validated using models of ideal and non-ideal solutions. Thereafter, experimentation was carried out for the sake of comparison with theoretical data. RESULTS: CHESS® software using models of ideal and non-ideal solutions were validated. The experimentation confirmed the theoretical data, and new formulas were assessed based on their physicochemical (pH, content, Osmolality) and microbiological stability. CONCLUSION: The new formulas defined here guarantee excellent physicochemical and microbiological stability of diagnostic solutions, indispensable criteria for harmonizing and comparing results from different specialized centers using NPD measurements. These new formulas apply to the harmonization approach of techniques for measuring the nasal transepithelial potential difference.

Determinants of the interindividual variability in serum cytidine deaminase activity of patients with solid tumours.

AIMS: Cytidine deaminase (CDA) activity in cancer patients' serum has been proposed as a predictive biomarker for efficacy and toxicity of nucleoside analogues. However, discrepant results about its predictive value have been reported due to the high interindividual variability in CDA activity. This study aimed at identifying determinants of this interindividual variability. METHODS: From December 2014 to November 2015, 183 patients were prospectively included. Serum CDA activity, biological and clinical characteristics as well as five common single nucleotide polymorphisms (SNPs) in the CDA gene (c.-451C > T, c.-92A > G, c.-33_-31delC, c.79A > C, c.435 T > C) were analysed. Associations between clinical characteristics, pharmacogenetic variants and CDA activity were univariately tested. P < 0.1-candidate variables were analysed through a multivariate analysis. The association between CDA activity and toxicity was assessed for the 56 gemcitabine-treated patients. Intraindividual variability in CDA activity was explored in six pancreatic cancer patients treated with gemcitabine. RESULTS: Median CDA activity was 3.97 U mg-1 (range 1.53-15.49 U mg-1 ). A univariate analysis showed that CDA activity was statistically associated with Eastern Cooperative Oncology Group performance status, mild or severe malnutrition, inflammatory syndrome, leucocyte count, neutrophil count, albumin, C-reactive protein and -c.-33_-31delC single nucleotide polymorphism. A multivariate analysis identified that only neutrophil count (P < 0.0001) and severe malnutrition (P = 0.0278) were independently associated with CDA activity. Low CDA activity (<2 U mg-1 ) was not statistically associated with severe gemcitabine-related toxicities (P = 0.16). A decrease in CDA activity was observed during the longitudinal follow-up of six pancreatic cancer patients treated with gemcitabine (P = 0.03). CONCLUSIONS: These results suggest that neutrophil count and malnutrition should be considered for the interpretation of pretherapeutic CDA activity.

Arsenite medicinal use, metabolism, pharmacokinetics and monitoring in human hair.

Acute promyelocytic leukaemia (APL) is a distinctive subtype of acute myeloid leukaemias. Even through this human disease can be treated by the intravenous administration of all-trans retinoic acid (ATRA), 25% of patients typically relapse after the first treatment. In this context, the intravenous administration of APL patients with an aqueous solution of arsenic trioxide has also been demonstrated to be successful despite the established mammalian toxicity of this arsenic compound. Accordingly, the administration of a therapeutic dose of arsenic trioxide has resulted in an improved patient survival in both relapsing as well newly diagnosed APL patients. We present here a mini-review of the medicinal use of arsenite, its mammalian metabolism (with an emphasis on biomethylation pathways), its elimination and pharmacokinetics and the novel application of hair analysis as a biomonitoring material. This mini-review also introduces our own results on the analysis of hair of patients receiving arsenic trioxide therapy. In this work, instead of quantifying arsenic content in bulk hair, we performed longitudinal analysis in order to use hair as a marker of arsenic exposure correlated to a time scale. Taking into account the hair growth rate, the longitudinal analysis of hair is demonstrated to provide a chronological record of the treatment of patients with arsenic trioxide. The small quantity of material to be analysed required the use of Synchrotron radiation based X-ray fluorescence (SXRF) spectroscopy. The hair arsenic content was well correlated with the clinical background of patients and reflected the intake of arsenic trioxide. In particular, the onset of arsenic trioxide therapy and interruptions during therapy were reflected by total arsenic content, which suggested rapid elimination. Another type of experiment, micro-XRF cartography on thin hair slices, allowed us to obtain distribution maps of arsenic, which demonstrated that arsenic is located at the periphery of hair. Micro-XANES spectra recorded at the periphery of hair, suggest that inorganic arsenic is incorporated in hair in its trivalent oxidation state, in agreement with previous results.

Short-chain fatty acids and polyamines in the pathogenesis of necrotizing enterocolitis: Kinetics aspects in gnotobiotic quails.

Despite years of investigation, pathogenesis of necrotizing enterocolitis (NEC) remains elusive. Bacterial metabolites were implicated by several authors but their roles remain controversial. The aim of our study was to investigate the role of SCFAs and polyamines through a kinetic study of histological and macroscopical digestive lesions in monobiotic quails. Germ-free quails, inoculated with a Clostridium butyricum strain involved in a NEC case, were fed or not with a diet including lactose (7%). Quails were sacrificed at various times between D7 and D24 after bacterial inoculation. NEC-like lesions, i.e. thickening, pneumatosis, and hemorrhages, occurred only in lactose-fed quails and increased with time. The main histological characteristics were infiltrates of mononuclear cells, then heterophilic cells, then gas cyst and necrosis. The first event observed, before histological and macroscopical lesions, is a high production of butyric acid, which precedes an increase of iNOS gene expression. No difference in polyamines contents depending on the diet was observed. These results show the major role of butyric acid produced by commensal bacteria in the onset of the digestive lesions.

Carboplatin and oxaliplatin decomposition in chloride medium, monitored by XAS.

The stability of carboplatin and oxaliplatin aqueous solutions has been studied under different chloride ions concentration and pH conditions. For both compounds, we demonstrate the chloration of the platinum first coordination shell.

XAS applied to pharmaceuticals: drug administration and bioavailability.

We present selected XAS applications, focused towards practical hospital questions of drug administration and bioavailability, where the technique is driven up to its limits of sensitivity. i) XAS was used to study the interactions between the components of parenteral nutrition solutions, in particular zinc and aminoacids, possibly modifying their bioavailability. ii) We studied by EXAFS a series of binary and ternary copper-aminoacid complexes, in view of the development of an efficient oral drug against copper deficiencies in Menkes disease. iii) EXAFS and XANES analysis allowed us to characterise the solution form of a new arsenic containing drug against leukaemia. In parallel to the XAS measurements, we analysed trace elements levels along patients' hairs, using X-ray fluorescence excited by synchrotron radiation. The measurements along the hair allow for a monitoring of essential trace elements during therapy.