Synthesis and Biological Activity of Chloroethyl Pyrimidine Nucleosides

The synthesis and biological activity of chloroethyl pyrimidine nucleosides is presented. One of these new nucleosides analogues significantly inhibited cell proliferation, migration and invasion as tested in vitro on the A431 vulvar epidermal carcinoma cell line.     

Treatment of fruit waste leachate using microbial fuel cell: Preservation of agricultural environment

A microbial fuel cell (MFC) was conceived to low electric power production in parallel to valorization of industrial wastes and environment preservation. It consisted of two compartments separated by polymer Nafion membrane, platinum grid as cathode catalyst and graphite rod inoculated with fruit leachate as bio-anode. Owing to its bio-compatibity with bacterial inoculum and chemical stability, Graphite Carbon (GC) was tested as carrier of biofilm using fruit waste inoculum. The maximum power density harvested with this electrode was about 20 mW.m^?2 much greater than that obtained previously with a garden compost inoculum (i.e. 7 mW.m^?2). The difference between the two values may be attributed to the bacterial nature of inoculum utilized. Impressively, upon the addition of 6 mL of fuel (sucrose), the soft porous graphite felt GF yielded voltage (260 mV) which was significantly higher than that of the hard smooth solid GC (i.e. 140 mV). This result makes in evidence the effect of adsorption of the electro-active biofilm onto the surface of the electrode. We ascribe therefore the enhanced power density to a more uniform spread out of the electro-active biofilm within the GF matrix, as verified by higher conductivity obtained with four probe method. The results reported herein highlight the importance of assessing the bio-catalytic activity towards the oxidation of the organic substrate to yield renewable low energy. The experimental data and the differences between the bio-anodes GC and GF were discussed in term of electrochemical techniques such as cyclic voltammetry, impedance spectroscopy and four-probe conductivity. Whatever the nature of the bio-anodes, the overall bacterial colonization still yields low values of clean electric energy compared to highly polluted energy obtained with an alkaline fuel cell.     

HIV-Associated Histoplasmosis Early Mortality and Incidence Trends: From Neglect to Priority

Background

Histoplasmosis is an endemic fungal infection in French Guiana. It is the most common AIDS-defining illness and the leading cause of AIDS-related deaths. Diagnosis is difficult, but in the past 2 decades, it has improved in this French overseas territory which offers an interesting model of Amazonian pathogen ecology. The objectives of the present study were to describe the temporal trends of incidence and mortality indicators for HIV-associated histoplasmosis in French Guiana.

Methods

A retrospective study was conducted to describe early mortality rates observed in persons diagnosed with incident cases of HIV-associated Histoplasma capsulatum var. capsulatum histoplasmosis admitted in one of the three main hospitals in French Guiana between 1992 and 2011. Early mortality was defined by death occurring within 30 days after antifungal treatment initiation. Data were collected on standardized case report forms and analysed using standard statistical methods.

Results

There were 124 deaths (45.3%) and 46 early deaths (16.8%) among 274 patients. Three time periods of particular interest were identified: 1992–1997, 1998–2004 and 2005–2011. The two main temporal trends were: the proportion of early deaths among annual incident histoplasmosis cases significantly declined four fold (χ2, p<0.0001) and the number of annual incident histoplasmosis cases increased three fold between 1992–1997 and 1998–2004, and subsequently stabilized.

Conclusion

From an occasional exotic diagnosis, AIDS-related histoplasmosis became the top AIDS-defining event in French Guiana. This was accompanied by a spectacular decrease of early mortality related to histoplasmosis, consistent with North American reference center mortality rates. The present example testifies that rapid progress could be at reach if awareness increases and leads to clinical and laboratory capacity building in order to diagnose and treat this curable disease.     

Screening and identification of epiphytic yeasts with potential for biological control of green mold of citrus fruits

Epiphytic yeasts isolated from the surface of citrus fruits, harvested in several orchards in the Souss-Massa-Draa Valley, Agadir, Morocco, were in vivo screened for antagonistic activity against Penicillium digitatum, the causal agent of green mold of citrus. From a total of 245 yeast strains assessed for their biocontrol activity against P. digitatum, fifteen reduced the incidence of disease to less than 50%. The effectiveness of the best selected yeast strains showed that Pichia anomala (YT73), Debaryomyces hansenii (YT22) and Hanseniaspora guilliermondii (YT13) were the most effective, with a reduction of green mold incidence from 65 to ~80%, compared to the control. The identification of the fifteen selected yeast strains was carried out through an integrated approach including phenotypic and genotypic (sequencing of D1/D2 domain of 26S rDNA encoding gene) methods. These 15 selected were identified as: H. guilliermondii, D. hansenii, H. uvarum and P. anomala. The study of the dynamics of two of the best strains, H. guilliermondii and D. hansenii, showed that these strains can grow rapidly, by approximately 2 log units, in citrus fruit wounds. Such rapid growth in wounds indicates that these antagonist yeasts are excellent colonizers of citrus wounds and can thrive on citrus fruits as a substrate.     

Delivery of steric block morpholino oligomers by (R-X-R)4 peptides: structure-activity studies

Redirecting the splicing machinery through the hybridization of high affinity, RNase H- incompetent oligonucleotide analogs such as phosphoramidate morpholino oligonucleotides (PMO) might lead to important clinical applications. Chemical conjugation of PMO to arginine-rich cell penetrating peptides (CPP) such as (R-Ahx-R)₄ (with Ahx standing for 6-aminohexanoic acid) leads to sequence-specific splicing correction in the absence of endosomolytic agents in cell culture at variance with most conventional CPPs. Importantly, (R-Ahx-R)₄–PMO conjugates are effective in mouse models of various viral infections and Duchenne muscular dystrophy. Unfortunately, active doses in some applications might be close to cytotoxic ones thus presenting challenge for systemic administration of the conjugates in those clinical settings. Structure–activity relationship studies have thus been undertaken to unravel CPP structural features important for the efficient nuclear delivery of the conjugated PMO and limiting steps in their internalization pathway. Affinity for heparin (taken as a model heparan sulfate), hydrophobicity, cellular uptake, intracellular distribution and splicing correction have been monitored. Spacing between the charges, hydrophobicity of the linker between the Arg-groups and Arg-stereochemistry influence splicing correction efficiency. A significant correlation between splicing correction efficiency, affinity for heparin and ability to destabilize model synthetic vesicles has been observed but no correlation with cellular uptake has been found. Efforts will have to focus on endosomal escape since it appears to remain the limiting factor for the delivery of these splice-redirecting ON analogs.     

In-vitro regeneration of olive tree by somatic embryogenesis

We induced somatic embryogenesis from the cotyledon segments ofOlea europaea (L) cvs. ‘Chetoui’, ‘Chemleli’, and ‘Arbequina’. Calli were established from all three cultvars on OMc media supplemented with IBA and 2i-R The greatest success was obtained with media that contained zero or low concentrations of growth regulators. High levels of hormones (i.e.,>0.5 mgL^-1 IBA and 2i-P) inhibited embryogenesis. Embryos at different maturation stages were observed with continuously proliferating secondary embryogenesis. Abnormally shaped embryos and teratoma were also noted. Four weeks was the optimal incubation period for inducing embryogenesis on the auxin-containing medium. In addition, 30 to 40 gL^-1 sucrose was more effective than glucose in stimulating the growth and maturation of somatic embryos. Embryogeic efficiency was also higher when multivariate combinations of nitrogen sources (inorganic and organic nitrogen forms) were used. The plantlets that were derived from our germinating somatic embryos were similar to those obtained from axillary buds.     

Is Fe deficiency rather than P deficiency the cause of cluster root formation in Casuarina species?

When subjected, directly (through nutritional deficiencies) or indirectly (through alkaline constraints leading to such deficiencies) to nutrient deficiencies, certain plants respond by developing special root structures called cluster roots. This phenomenon can be considered as an ecophysiological response to a specific nutrient deficiency enabling plants to enhance nutrient uptake. Experiments conducted on an alkaline and an acid soil showed that Casuarina glauca (Sieber ex Spreng.) produced cluster roots only in the alkaline soil and not in the acid soil. In addition, iron (Fe) and phosphorus (P) deficiencies were examined separately or together to determine their effect on cluster root formation in C. glauca seedlings grown hydroponically. Results from experiments carried out on three Casuarina species (C. glauca, C. cunninghamiana Miq. and C. equisetifolia L.) indicated that Fe is involved in cluster root formation. In nutrient media lacking P but containing Fe, no cluster roots formed while seedlings receiving P and lacking Fe developed cluster roots. When incubated on chrome-azurol S-agar on blue plates (CAS assay), a technique used routinely to detect the production of siderophores by micro-organisms, the root system of Fe-deficient plants exhibited orange halos around cluster roots, indicating production of a ferric-chelating agent. It is concluded that the capacity of cluster roots of C. glauca to chelate Fe allows the plant to grow normally on alkaline soils.     

Tetra-n-propylammonium tetra-oxoruthenate(VII): a reagent of choice for the oxidation of diversely protected glycopyranoses and glycofuranoses to lactones

2,3,4,6-Tetra-O-benzyl- -glucopyranose, 2,3,5-tri-O-allyl- -ribofuranose, 2,3,5-tri-O-allyl- and -tri-O-benzyl- -arabinofuranose, and 2-deoxy-3,5-di-O-allyl- -erythro-pentofuranose were oxidized to their corresponding lactones 6–10 by dimethyl sulfoxide activated by oxalyl chloride, pyridinium dichromate in the presence of molecular sieves and acetic acid, and tetra-n-propylammonium tetra-oxoruthenate(VII) using 4-methylmorpholine N-oxide as cooxidant. With the latter reagent, analytically pure lactones were obtained in 83–98% yield. A multistep preparation of 3,4,6-tri-O-benzyl-2-deoxy- -arabino-hexono-1,5-lactone (14) from 3,4,6-tri-O-benzyl-1,5-anhydro-2-deoxy- -arabino-hex-1 enitol (65% overall yield) is described.     

Synthesis and Biological Activity of Mustard Derivatives of Thymine

The synthesis and biological activity of a novel DNA cross-linking antitumor agent is presented. The new alkylating agent significantly inhibited cell proliferation, migration and invasion as tested in vitro on the A431 vulvar epidermal carcinoma cell line.     

Are Orai1 and Orai3 channels more important than calcium influx for cell proliferation?

Transformed and tumoral cells share the characteristic of being able to proliferate even when external calcium concentration is very low. We have investigated whether Human Embryonic Kidney 293 cells, human hepatoma cell Huh-7 and HeLa cells were able to proliferate when kept 72 h in complete culture medium without external calcium. Our data showed that cell proliferation rate was similar over a range of external calcium concentration (2 μM to 1.8 mM). Incubation in the absence of external calcium for 72 h had no significant effect on endoplasmic reticulum (ER) Ca^2 + contents but resulted in a significant decrease in cytosolic free calcium concentration in all 3 cell types. Cell proliferation rates were dependent on Orai1 and Orai3 expression levels in HEK293 and HeLa cells. Silencing Orai1 or Orai3 resulted in a 50% reduction in cell proliferation rate. Flow cytometry analysis showed that Orai3 induced a small but significant increase in cell number in G₂/M phase. RO-3306, a cdk-1 inhibitor, induced a 90% arrest in G₂/M reversible in less than 15 min. Our data showed that progression through G₂/M phase after release from RO-3306-induced cell cycle arrest was slower in both Orai1 and Orai3 knock-downs. Overexpressing Orai1, Orai3 and the dominant negative non-permeant mutants E106Q-Orai1 and E81Q-Orai3 induced a 50% increase in cell proliferation rate in HEK293 cells. Our data clearly demonstrated that Orai1 and Orai3 proteins are more important than calcium influx to control cell proliferation in some cell lines and that this process is probably independent of I_CRAC and I_arc.