Are Cytochrome P450 CYP2C8 and CYP2C9 Polymorphisms Associated with Ibuprofen Response in Very Preterm Infants?

Background

Patent ductus arteriosus (PDA) in extremely preterm infants remains a challenging condition with conflicting treatment strategies. Ibuprofen is currently used to treat PDA with ductal closure failure rate up to 40%. We test the hypothesis that cytochrome P450 CYP2C8/2C9 polymorphisms may predict ibuprofen response.

Methodology/Principal Findings

We studied extremely preterm neonates with haemodynamically significant PDA and treated with ibuprofen. One or two variant CYP2C8 and/or 2C9 alleles were found in 17% of the population, most of them were from Caucasian ethnicity (67–74%). Response to ibuprofen and clinical course of infants carrying variants CYP2C8 and CYP2C9 were similar. Comparing infants with wild type or variant CYP2C8 and CYP2C9 genotypes, response rate to ibuprofen was significantly higher in wild type than in mutated carriers in univariate analysis (73% versus 52%, p = 0.04). Comparing responders (ductus closure; n = 75) and non-responders (surgical ligation; n = 36), the only two factors significantly associated with the response to ibuprofen using multivariate analysis were higher gestational age and non Caucasian ethnicity but not CYP2C polymorphism.

Conclusions

CYP2C polymorphism was not associated with PDA response to ibuprofen and this factor appears not appropriate to optimize the ductal closure rate by modulating ibuprofen dosing strategy. This study points out the role for ethnicity in the interindividual variability of response to ibuprofen in extremely preterm infants.     

Occurrence of mycorrhizal symbioses in the metal-rich lateritic soils of the Koniambo Massif, New Caledonia

The occurrence of arbuscular mycorrhiza (AM) was surveyed in ten endemic plant species of the Koniambo Massif (New Caledonia) and associated metal-enriched ultramafic soils along a topographic sequence ranging from a plateau at 900 m altitude to a valley at 700 m. In the four different plant formations (Araucaria group on the plateau, ligno-herbaceous maquis, Tristaniopsis maquis and Nothofagus forest in the valley), all plants were consistently colonised by AM fungi, even the sedges Costularia arundinacea, C. nervosa and Lepidosperma perteres and the nickel-hyperaccumulating plant Phyllanthus favieri. Dual (AM and ectomycorrhiza EM) colonisation was observed in the two plant formations dominated by the ectomycorrhizal plants Nothofagus balansae for the forest (site 4) and Tristaniopsis guillainii and T. calobuxus for the Tristaniopsis maquis (site 3). In the soils, there are strong positive correlations between microbial activity, black AM spore abundance and concentrations of available metals indicating the role of the biotic component in the release of metals. These results suggest that these symbioses are important in the adaptation of the endemic plants to these soils, and may be relevant to ecological restoration of the ancient nickel mines.     

Towards functional glycomics by localization of binding sites for tissue lectins: lectin histochemical reactivity for galectins during diethylstilbestrol-induced kidney tumorigenesis in male Syrian hamster

Endogenous lectins act as effectors of cellular activities such as growth regulation, migration, and adhesion. Following their immunohistochemical localization in our previous study (Saussez et al. in Histochem Cell Biol 123:29–41, 2005) we purified several galectins and used them as tools for monitoring accessible binding sites. Herein, we report the use of galectin histochemistry for the analysis of diethylstilbestrol (DES)-induced renal tumors in male Syrian hamster kidney (SHKT). Sections of normal kidney and DES-treated kidney were analyzed with biotinylated galectins-1, -3 (full-length and truncated), and -7. Accessible binding sites were detected, localization was predominantly extracellular and confined to medium-sized and large tumors. Monitoring the SHKT-derived HKT-1097 line, processed in vitro or as xenograft material, cytoplasmic and nuclear staining for galectins-1, -3, and -3tr could be observed. Adaptation of SHKT cells to long-term growth in culture is thus associated with emergence of this signal. Our data set illustrates the feasibility to complement immunohistochemical data by application of the tissue lectins as probes, and to detect regulation of galectin reactivity with differential characteristics within tumor progression in vivo and unique features of the tumor cell line in vitro and in vivo.     

Synthesis and biological evaluation of new dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraones, substituted with various saturated and unsaturated side chains via palladium catalyzed cross-coupling reactions

The syntheses of a series of dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraones, substituted in 10-position with saturated and unsaturated side chains, via palladium catalyzed cross-coupling reactions, are described. These compounds can be considered as granulatimide bis-imide analogues. Their inhibitory activity toward Chk1 kinase and their antiproliferative activities in vitro in four tumor cell lines are reported.     

Plastidial phosphorylase is required for normal starch synthesis in Chlamydomonas reinhardtii

Among the three distinct starch phosphorylase activities detected in Chlamydomonas reinhardtii, two distinct plastidial enzymes (PhoA and PhoB) are documented while a single extraplastidial form (PhoC) displays a higher affinity for glycogen as in vascular plants. The two plastidial phosphorylases are shown to function as homodimers containing two 91-kDa (PhoA) subunits and two 110-kDa (PhoB) subunits. Both lack the typical 80-amino-acid insertion found in the higher plant plastidial forms. PhoB is exquisitely sensitive to inhibition by ADP-glucose and has a low affinity for malto-oligosaccharides. PhoA is more similar to the higher plant plastidial phosphorylases: it is moderately sensitive to ADP-glucose inhibition and has a high affinity for unbranched malto-oligosaccharides. Molecular analysis establishes that STA4 encodes PhoB. Chlamydomonas reinhardtii strains carrying mutations at the STA4 locus display a significant decrease in amounts of starch during storage that correlates with the accumulation of abnormally shaped granules containing a modified amylopectin structure and a high amylose content. The wild-type phenotype could be rescued by reintroduction of the cloned wild-type genomic DNA, thereby demonstrating the involvement of phosphorylase in storage starch synthesis.     

Improved antitumoral properties of pure antiestrogen RU 58668-loaded liposomes in multiple myeloma

In most of multiple myeloma (MM) cells, the "pure" antiestrogen (AE) RU 58668 (RU) induced either a G1-arrest (LP-1, OPM-2, NCI-H929, U266 cells) or apoptosis (RPMI 8226 cells). In RPMI 8226 cells, RU activates a caspase-dependent cell death pathway leading to the release of cytochrome c, the decrease of the essential MM survival factor Mcl-1, the cleavage of Bid and the activation of caspases-3 and -8. Incorporation of RU in pegylated cholesterol-containing liposomes allowed a controlled RU release, improving its anti-proliferative and apoptotic effects in cells. In RPMI 8226 xenografts, i.v. injected RU-liposomes but not free RU, exhibited antitumor activity. In vivo, RU-liposomes triggered the mitochondrial death pathway, concomitantly with a down-regulation of Mcl-1 and Bid cleavage. The decrease of CD34 immunoreactivity indicated a reduction of angiogenesis. The decrease of VEGF secretion in vitro supported a direct effect of RU on angiogenesis. These pro-apoptotic and antiangiogenic effects were explained by a prolonged exposure to the drug and to the endocytosis capacity of liposomes which might increase RU uptake and bypass a membrane export of free RU. Thus, these combined enhanced activities of RU-liposomes support that such a delivery of an AE may constitute a strategy of benefit for MM treatment.     

The X-ray structure of the N-terminal domain of PILB from Neisseria meningitidis reveals a thioredoxin-fold

The secreted form of the PilB protein was recently shown to be bound to the outer membrane of Neisseria gonorrhoeae and proposed to be involved in survival of the pathogen to the host's oxidative burst. PilB is composed of three domains. The central and the C-terminal domains display methionine sulfoxide reductase (Msr) A and B activities respectively, i.e. the ability to reduce specifically the S and the R enantiomers of the sulfoxide function of the methionine sulfoxides, which are easily formed upon oxidation of methionine residues. The N-terminal domain of PilB (Dom1(PILB)) of N.meningitidis, which possesses a CXXC motif, was recently shown to recycle the oxidized forms of the PilB Msr domains in vitro, as the Escherichia coli thioredoxin (Trx) 1 does. The X-ray structure of Dom1(PILB) of N.meningitidis determined here shows a Trx-fold, in agreement with the biochemical properties of Dom1(PILB). However, substantial structural differences with E.coli Trx1 exist. Dom1(PILB) displays more structural homologies with the periplasmic disulfide oxidoreductases involved in cytochrome maturation pathways in bacteria. The active site of the reduced form of Dom1(PILB) reveals a high level of stabilization of the N-terminal catalytic cysteine residue and a hydrophobic environment of the C-terminal recycling cysteine in the CXXC motif, consistent with the pK(app) values measured for Cys67 (<6) and Cys70 (9.3), respectively. Compared to cytochrome maturation disulfide oxidoreductases and to Trx1, one edge of the active site is covered by four additional residues (99)FLHE(102). The putative role of the resulting protuberance is discussed in relation to the disulfide reductase properties of Dom1(PILB).     

Assignment of a kinetic component to electron transfer between iron-sulfur clusters F(X) and F(A/B) of Photosystem I

We studied the kinetics of reoxidation of the phylloquinones in Chlamydomonas reinhardtii Photosystem I using site-directed mutations in the PhQ(A)-binding site and of the residues serving as the axial ligand to ec3(A) and ec3(B) chlorophylls. In wild type PS I, these kinetics are biphasic, and mutations in the binding region of PhQ(A) induced a specific slowing down of the slow component. This slowing allowed detection of a previously unobserved 180-ns phase having spectral characteristics that differ from electron transfer between phylloquinones and F(X). The new kinetic phase thus reflects a different reaction that we ascribe to oxidation of F(X)(-) by the F(A/B) FeS clusters. These absorption changes partly account for the differences between the spectra associated with the two kinetic components assigned to phylloquinone reoxidation. In the mutant in which the axial ligand to ec3(A) (PsaA-Met688) was targeted, about 25% of charge separations ended in P(700)(+)A(0)(-) charge recombination; no such recombination was detected in the B-side symmetric mutant. Despite significant changes in the amplitude of the components ascribed to phylloquinone reoxidation in the two mutants, the overall nanosecond absorption changes were similar to the wild type. This suggests that these absorption changes are similar for the two different phylloquinones and that part of the differences between the decay-associated spectra of the two components reflect a contribution from different electron acceptors, i.e. from an inter-FeS cluster electron transfer.