Facile synthesis and detailed characterization of a new ferrocenyl uracil peptide nucleic acid monomer

A new ferrocenyl uracil peptide nucleic acid (PNA) monomer, tert-butyl-2-(N-(2-(((9H-floren-9-yl)methoxy)carbonylamino)ethyl)-2-(5-(N-ferrocenylmethylbenzamido)-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamido)acetate (1), has been successfully prepared in good yield by a procedure involving the one-pot reaction of the key synthon, 5-(ferrocenylmethylamino)pyrimidine-2,4(1H,3H)-dione (4), itself prepared from the reaction of (ferrocenylmethyl)trimethylammonium iodide and 5-aminouracil, with benzoyl chloride followed by ethyl bromoacetate. After hydrolysis of the ester, the acid was coupled with a protected PNA backbone to generate 1. NMR spectroscopy showed that 1 hydrogen bonds 9-ethyladenine (EA) in a 1:1 mixture of CD3CN:CDCl3 with an association constant Ka of 70 M(-1) at 30 degrees C. This value is comparable with those observed for model receptors and shows that the ferrocenyl moiety of 1 does not hinder the hydrogen bonding of our new PNA monomer to the complementary DNA base or if it does, not significantly. 1 is oxidized to 1+ with a reversible potential of +538 mV vs the DMFc(0/+) (decamethylferrocene) couple under voltammetric conditions in a 1:1 mixture of CH3CN:CHCl3 (0.1 M Bu4NPF6). For this reversible process, a slightly larger diffusion coefficient of 4.2 x 10(-6) cm(2).s(-1) than usually found for these compounds was determined from these electrochemical studies, which should be analytically useful as it will readily afford submicromolar voltammetric detection limits.     

Genetics and congenital malformations: interpretations, attitudes and practices in suburban communities and the shamans of ecuador

OBJECTIVES: The purpose of the present article was to evaluate how shamans and the suburban communities of Quito interpret the terminology used in genetics. METHODS: One hundred people living in 5 suburban districts of Quito were surveyed as well as 19 shamans of the Salasaca community. RESULTS: The results show that members of both groups are little informed about genetics. As knowledge about genetics is correlated to educational level, which is very poor in both groups, knowledge and understanding of genetics are either very basic or nonexistent. As for the medical practices in treating genetic alterations, the surveys show that while in very severe cases scientific medicine is sought, in most cases explanations and a cure are given by shamanic medicine. CONCLUSION: There is limited knowledge of genetics and its terminology in the study population. Shamanic and marginal health practices seem to remain prevalent in these communities due to their low costs, the personal attention the individuals receive, and the holistic point of view employed. It is important that the community councils, the medical doctors and the shamans work together to set up community programs on medical education, particularly on genetics.     

On the Complexity of Parallel Algorithms for Computing Inverses in GF(2^m) with m Prime

Inversion over a finite field is usually an expensive operation which is a crucial issue in many applications, such as cryptography and error-control codes. In this paper, three different strategies for computing the inverse over binary finite fields , called Eulerian, Gaussian, and Euclidean, respectively, are discussed and compared in terms of time and space complexity. In particular, some new upper and lower bounds to the respective complexities are evaluated.     

Efficient hydrogen peroxide generation from organic matter in a bioelectrochemical system

Hydrogen peroxide (H₂O₂) is an important industrial chemical, but its current production methods are highly energy-intensive. This study presents a novel process for the production of H₂O₂ based on the bioelectrochemical oxidation of wastewater organics at an anode coupled to the cathodic reduction of oxygen to H₂O₂. At an applied voltage of 0.5 V, this system was capable of producing 1.9 ± 0.2 kg H₂O₂/m³/day from acetate at an overall efficiency of 83.1 ± 4.8%. As most of the required energy was derived from the acetate, the system had a low energy requirement of 0.93 kWh/kg H₂O₂.     

Photoluminescence at 1.9 eV in synthetic wet silica

We report the effects of γ-irradiation on the optical activity of wet synthetic silica samples. As a function of γ-dose, the growth of a composite structure in the 4–6 eV spectral region of the absorption spectrum is observed. This structure can be resolved into two main contributions centered at 5.8 and 4.8 eV, respectively. The first component is usually attributed to an optical transition of the E^′ centers. The second one is able to excite an emission band centered at 1.9 eV. The analysis of the growth kinetics, in the γ-dose range 20–1000 Mrad, of both emission at 1.9 eV and absorption at 4.8 eV shows that these two bands change in a similar way, reaching constant amplitudes, after an initial linear increase, at a dose depending on the OH content. In addition, their ratio is independent of the sample. These results are consistent with a structural model in which the observed optical activity arises from a single-point defect induced by γ-irradiation. Moreover, based on the correlation with the OH content in our samples, we suggest that the principal candidate for this point defect is the non-bridging oxygen hole center (HBOHC).     

Electrochemical, spectroelectrochemical and theoretical studies on the reduction and deprotonation of the photovoltaic sensitizer [(H3-tctpy)Ru(NCS)3] (H3-tctpy=2,2′:6′,2′′-terpyridine-4,4′,4′′-tricarboxylic acid)

The electrochemical reduction of the black dye photosensitizer [(H₃-tctpy)Ru^II(NCS)₃]⁻ (H₃-tctpy=2,2′:6′,2′′-terpyridine-4,4′,4′′-tricarboxylic acid) used in photovoltaic cells has been found to be a complex process when studied in dimethylformamide. At low temperatures, fast scan rates and at a glassy carbon electrode, the chemically reversible ligand based one-electron reduction process [(H₃-tctpy)Ru(NCS)₃]⁻+e⁻[(H₃-tctpy√⁻)Ru(NCS)₃]²⁻ is detected. This process has a reversible half-wave potential (E^r_1/2) of −1585±20 mV versus Fc/Fc⁺ at 25°C. Under other conditions, a deprotonation reaction occurs upon reduction, which produces [(H_3−x-tctpy^x−)Ru(NCS)₃]^(1+x)− and hydrogen gas. Mechanistic pathways giving rise to the final products are discussed. The E^r_1/2-value for the ligand based reductions of the deprotonated complex is 0.70 V more negative than for [(H₃-tctpy)Ru(NCS)₃]⁻. Consequently, data obtained from molecular orbital calculations are consistent with the reaction [(H₃-tctpy)Ru(NCS)₃]⁻+e⁻→[(H₂-tctpy⁻)Ru(NCS)₃]²⁻+1/2H₂ yielding the monodeprotonated complex as the major product obtained after electrochemical reduction of [(H₃-tctpy)Ru(NCS)₃]⁻. The E^r_1/2-values for the metal based Ru^II/III process differ by 0.30 V when data obtained for the protonated and deprotonated forms of the black dye are compared. Electronic spectra obtained during the course of experiments in an optically transparent thin layer electrolysis configuration are consistent with the overall reaction scheme proposed on the basis of voltammetric measurements and molecular orbital calculations. Reduction studies on the free ligand, H₃-tcpy, are consistent with results obtained with [(H₃-tctpy)Ru(NCS)₃]⁻.     

Phenolic Characterization and Neuroprotective Properties of Grape Pomace Extracts

Vitis vinifera (grape) contains various compounds with acknowledged phytochemical and pharmacological properties. Among the different parts of the plant, pomace is of particular interest as a winemaking industry by-product. A characterization of the water extract from grape pomace from Montepulciano d’Abruzzo variety (Villamagna doc) was conducted, and the bioactive phenolic compounds were quantified through HPLC-DAD-MS analysis. HypoE22, a hypothalamic cell line, was challenged with an oxidative stimulus and exposed to different concentrations (1 µg/mL⁻¹ mg/mL) of the pomace extract for 24, 48, and 72 h. In the same conditions, cells were exposed to the sole catechin, in a concentration range (5–500 ng/mL) consistent with the catechin level in the extract. Cell proliferation was investigated by MTT assay, dopamine release through HPLC-EC method, PGE₂ amount by an ELISA kit, and expressions of neurotrophin brain-derived neurotrophic factor (BDNF) and of cyclooxygenase-2 (COX-2) by RT-PCR. The extract reverted the cytotoxicity exerted by the oxidative stimulus at all the experimental times in a dose-dependent manner, whereas the catechin was able to revert the oxidative stress-induced depletion of dopamine 48 h and 72 h after the stimulus. The extract and the catechin were also effective in preventing the downregulation of BDNF and the concomitant upregulation of COX-2 gene expression. In accordance, PGE₂ release was augmented by the oxidative stress conditions and reverted by the administration of the water extract from grace pomace and catechin, which were equally effective. These results suggest that the neuroprotection induced by the extract could be ascribed, albeit partially, to its catechin content.     

13C-enriched end groups of poly(3,7-dimethyl-1-octene) prepared in the presence of isotactic specific catalysts

Polymerizations of (R,S)-3,7-dimethyl-1-octene in the presence of heterogeneous or homogeneous isotactic specific catalysts give very similar products with a homopolymeric isotactic structure. The insertion of (R,S)-3,7-dimethyl-1-octene into the metal-CH₃ bond (both heterogeneous and homogeneous catalysts) is highly stereospecific and stereoselective.     

Copolymerization of ethylene and styrene to a nearly-alternating crystalline copolymer

An almost alternating stereoregular copolymer can be obtained by copolymerizing ethylene and styrene with the catalyst ethylenebis(1-indenyl)zirconium dichloride activated by methylaluminoxane at −25°C. The regular microstructure pointed out by the NMR spectrum allows the copolymer to crystallize as shown by calorimetric and X-ray diffraction measurements.     

Polysaccharides based hydrogels for biological applications

Polysaccharides based hydrogels show several peculiar properties which can be so reassumed: • Capability to absorb a great amount of water once immersed in biological fluids, assuming, consequently, a structure similar to extracellular matrix or biological tissue • Tissotropic property, i.e. possibility to be injected through a needle without lose of their rheological properties. These fundamental properties make them ideal materials for several biomedical applications, such as cellular scaffold, coatings for biomedical disposals, treatments for different diseases, controlled release of drugs, etc. Hyaluronane, Carboxymethyl cellulose and Alginic acid based 50% hydrogels (i.e. 50% of the carboxylate groups present in the macromolecule chain were involved in the cross-linking reaction) are synthesised. Their effectiveness in promoting cells adhesion and proliferation was verified. Furthermore the possibility of injecting and sterilising hydrogels permitted to test the effect of Hyal 50% in the osteoarthritis therapy. It was found that the in vivo effect of Hyal 50% in the treatment of surgically created chondral defect in the rabbit knee was positive. These materials can be both chemically and morphologically modified. In fact, the insertion of sulphate groups increase their hemocompatibility as demonstred by the increase of TT (time necessary to turn the fibrinogen to thrombin). Furthermore microporous hydrogels were obtained and tested as drug controlled release systems.