[A severe G6PD deficiency revealed during a chemotherapy protocol including rasburicase]. / Un déficit sévère en G6PD découvert au décours d'une chimiothérapie avec utilisation de rasburicase.

We present here the case-report of a man with a severe G6PD deficiency revealed after the use of rasburicase (uricolytic drug) during a chemotherapy protocol. The genotypic analysis done to confirm the biochemical measurement revealed the 'Mediterranean mutation' at the hemizygous state (G6PD gene is located on chromosome X). Consequently to this diagnose, a search for G6PD deficiency has been performed (at the biochemical and genotypic levels) for the 9 children (7 daughters and 2 sons) of the proband. Surprisingly, one of his son was found to be hemizygous for the mediterranean mutation and one of his daughter appeared homozygous for this same mutation. This implies that the proband's wife (not studied) is certainly heterozygous for the mediterranean mutation, as it is very unlikely that this mutation had appeared de novo for two children of this couple.

[DEFI-ALPHA cohort and POLYGEN DEFI-ALPHA clinical research hospital programme. A study about clinical, biological and genetics factors associated with the occurrence and the evolution of hepatic complications in children with alpha-1 antitrypsin deficiency]. / Cohorte DEFI-ALPHA et projet hospitalier de recherche clinique POLYGEN DEFI-ALPHA. Étude des facteurs cliniques, biologiques et génétiques associés à l'apparition et à l'évolution de complications hépatiques chez les enfants présentant un déficit en alpha-1 antitrypsine.

INTRODUCTION: The alpha-1 antitrypsin (α1-AT) deficiency, most frequently caused by homozygosity for the Z variant (SERPINA1: c.1096 G>A; Glu342Lys), can give rise to two clinical patterns: (i) respiratory impairment with emphysema (mainly in adulthood) because of a pulmonary quantitative defect in anti-elastase activity; (ii) hepatic impairment (mainly in childhood) due to the misfolding of the PiZ protein which accumulates in hepatocytes thus providing cytotoxicity. CURRENT KNOWLEDGE: To date, the clinical and genetic factors responsible for the development of major hepatic injuries (fibrosis and portal hypertension) during childhood in PiZ patients are not known. METHODS: The DEFI-ALPHA cohort, created in 2008, aims to inventory and prospectively study all α1-AT deficient children diagnosed and included after occurrence of a hepatic sign. The POLYGEN DEFI-ALPHA PHRC has recently (2013) been added to the project to identify modifiers genes by two complementary approaches: (i) the candidate genes strategy with the SERPINA1, CFTR (cystic fibrosis gene), MAN1B1 and SORL1 genes, these two latter being implied in the degradation of misfolding proteins; (ii) the whole exome sequencing (WES) strategy in families in which the PiZ proband has a PiZ brother or sister free of any hepatic sign. EXPECTED RESULTS: The clinical parameter we want to explain is the apparition of a portal hypertension in PiZ children. In the DEFI-ALPHA project, three criteria will be tested: (i) age of inclusion in the cohort, (ii) the way of inclusion (neo-natal icterus or later hepatic impairment) and (iii) treatment or not with ursodesoxycholic acid and, if so, its duration. Genetically, polymorphisms on the SERPINA1 and MAN1B1 genes have already been associated in the literature with different clinical evolutions of the A1ATD but very inconstantly. Our study thus aims to confirm or not this association. The CFTR and SORL1 genes have never been studied in the α1-AT deficiency. Finally, the whole exome sequencing strategy could allow the discovery of new unexpected modifiers genes in this disease.

Decarboxylation of [1-(13)C]leucine by hydroxyl radicals.

The decarboxylation of [1-13C]leucine by hydroxyl radicals was studied by using gas chromatography-isotope ratio mass spectrometry (GC-IRMS) to follow the production of 13CO2. A Fenton reaction between a (Fe2+)-porphyrin and hydrogen peroxide under aerobic conditions yielded hydroxyl radicals. The decarboxylation rates (VLeu) measured by GC-IRMS were dependent on [1-13C]leucine, porphyrin and hydrogen peroxide concentrations. The 13CO2 production was also dependent on bicarbonate or carbon dioxide added in the reaction medium. Bicarbonate facilitated 13CO2 production, whereas carbon dioxide decreased 13CO2 production. Proton effects on some decarboxylation intermediates could explain bicarbonate or carbon dioxide effects. No effect on the decarboxylation rates was observed in the presence of the classical hydroxyl radicals scavengers dimethyl sulfoxide, mannitol, and uric acid. By contrast, a competitive effect with a strong decrease of the decarboxylation rates was observed in the presence of various amino acids: unlabeled leucine, valine, phenylalanine, cysteine, lysine, and histidine. Two reaction products, methyl-4 oxo-2 pentanoate and methyl-3 butanoate were identified by gas chromatography-mass spectrometry in comparison with standards. The present results suggest that [1-13C]leucine can participate to the coordination sphere of (Fe2+)-porphyrin, with a caged process of the hydroxyl radicals which cannot get out of the coordination sphere.

Oxidative decarboxylation of benzoic acid by peroxyl radicals.

A chemical model based on the thermal decomposition of AAPH (2,2'-azobis(2-amidinopropane) dihydrochloride is used for the production of peroxyl radicals. Peroxyl radicals induces the decarboxylation of [7-13C]benzoic acid and the production of 13CO2, which is measured by gas chromatography-isotope ratio mass spectrometry (GC-IRMS). The decarboxylation depends on temperature, AAPH, and benzoic acid concentrations. The decarboxylation also depends on the presence of oxygen. Electron spin resonance studies are performed to confirm the presence of peroxyl radicals under oxygen and of carbon-centered radicals in the absence of oxygen. Decarboxylation rates are measured in the presence of various antioxidants: ascorbate, dimethylsulfoxide, mannitol, and uric acid. It turns out that the decarboxylation is inhibited by each of these antioxidants. The ratio of decarboxylation rates, with and without the antioxidant, varies linearly with the antioxidant concentration. HPLC and GC-MS analyses of reaction products between benzoic acid and AAPH-derived radicals do not detect the presence of radical substitution products on the aromatic ring or the products derived from benzoic acid. There is no doubt that GC-IRMS is a powerful technique to investigate the effects of peroxyl radicals on benzoic acid. In addition, it is possible to follow the degradation of 13C-labeled chemical targets exposed to peroxyl radicals through the production of 13CO2.

Optical and mechanical characterization of evaporated SiO(2) layers. Long-term evolution.

Numerous characterizations were performed on 120-nm thick evaporated SiO(2) layers in order to understand how their features change as a function of deposition conditions and time. Density decreases with increasing deposition pressure. It governs all the layer properties (refractive index, hardness, and stress). In situ stress measurements show that stress can be divided into intrinsic and water-induced components, respectively linked to local density (outside the pores) and porosity. Intrinsic stress increase with decreasing pressure is explained by a diminution of the Si-O-Si bond angle (IR measurements). Long-term evolution is characterized by stress relaxation related to Si-O-Si strained bond hydrolysis.

Reverse isotope dilution analysis of 13CO2 using gas chromatography/isotope ratio mass spectrometry: application to the quantitative determination of 13CO2 released by human polymorphonuclear leukocytes.

We propose a new method for the quantitative determination of carbon dioxide released by a biological microgenerator: a suspension of human polymorphonuclear leukocytes (PMNL). This method is based on the reverse isotope dilution analysis by gas chromatography/isotope ratio mass spectrometry of 13CO2 released by PMNL in a controlled isotope abundance atmosphere containing 3% CO2. 13CO2 release is effective after PMNL stimulation in the presence of [13C]glucose, labeled on positions 1, 2 or 6. The validation of this method is carried out by the measurement of the isotope ratio 13CO2/12CO2 using known amounts of [13C]sodium hydrogen carbonate and the comparison with theoretical isotope abundances derived from various CO2 equilibria. Complete release of CO2 is achieved by the acidification of the medium. This method requires only few cells, displays high sensitivity and specificity and can be applied to the analysis of large series of samples using an automatic sample injector. In addition, this method can also be applied to other types of biological microgenerators of carbon dioxide.

Hb Aubenas [beta 62(B8)Glu-->Gly]: a new variant normally synthesized, affecting the same codon as in Hb E.

Hb Aubenas [beta 26(B8)Glu-->Gly] is a mildly unstable variant that was found in a French family without hematological or clinical features. The structural abnormality was determined by protein chemistry methods, including tandem mass spectrometry, and was confirmed by Apa I digestion of a polymerase chain reaction-amplified DNA fragment. Although the substitution involves the same residue as in Hb E, the new nucleotide sequence does not create an additional out-of-frame splice site. The mutated chain is therefore normally synthesized.

Hemoglobin Debrousse (beta 96[FG3]Leu-->Pro): a new unstable hemoglobin with twofold increased oxygen affinity.

Hemoglobin Debrousse (beta 96[FG3]Leu-->Pro) is a new unstable variant, with high oxygen affinity responsible, in the steady state, for an apparently well-compensated chronic hemolytic anemia. The functional properties of this variant are due to the replacement of a leucine residue which is involved in the hydrophobic environment of the proximal side of the heme. This electrophoretically neutral hemoglobin was found as a de novo case in a 6-year-old girl suffering from severe anemia with hemolysis and transient aplastic crisis, following infection by parvovirus B19.

Two new alpha chain variants: Hb Boghé [alpha58(E7)His-->Gln, alpha2], a variant on the distal histidine, and Hb CHarolles [alpha103(G10)His-Tyr, alpha1].

The present paper reports two new alpha-globin chain variants: Hb Boghé [alpha58(E7)His-->Gln, alpha2] and Hb Charolles [alpha103(G10)His-->Tyr, alpha1]. Hb Boghé was found in a 12-month-old girl who was treated for malignant histiocytosis at 9 months of age and received a bone marrow transplant from her sister. Hb Boghé was undetectable by isoelectrofocusing and high performance liquid chromatography of hemoglobins. It was only revealed by polyacrylamide gel electrophoresis of globin chains in the presence of urea-Triton X-100 and accounted for 10% of the total hemoglobin. Hb Charolles was detected in a 46-year-old patient who presented with microcytosis and hypochromia. It was easily detected by isoelectrofocusing and high performance liquid chromatography. Hb Charolles accounted for 11% of the total hemoglobin. Characterization of the two hemoglobin variants was achieved by DNA and restriction enzyme analyses. Oxygen equilibrium curves measured on whole blood with Hb Boghé were normal. DNA sequencing revealed the association of Hb Charolles with a common mutation of the alpha2 polyadenylation site: AATAAA-->AATAAG.

New alpha 2 globin chain variant with low oxygen affinity affecting the N-terminal residue and leading to N-acetylation [Hb Lyon-Bron alpha 1(NA1)Val --> Ac-Ala].

Hemoglobin Lyon-Bron was found in two members of a family of German ascent presenting with a moderate normocytic anemia. In this alpha 2 globin variant, the N-terminal valine of the chain was replaced by an alanine. Electrospray mass spectrometry of the alpha chain showed that, as normally, the initiator methionine was cleaved during globin processing but that the N alpha-terminal group was totally acetylated. This resulted in structural modifications of a region crucial for oxygen binding. As a consequence, hemoglobin Lyon-Bron displayed both a reduced chloride effect and a decreased oxygen affinity, this last point explaining the apparent anemia.