Changes in Antioxidant Defense Enzymes after d-amphetamine Exposure: Implications as an Animal Model of Mania

Studies have demonstrated that oxidative stress is associated with amphetamine-induced neurotoxicity, but little is known about the adaptations of antioxidant enzymes in the brain after amphetamine exposure. We studied the effects of acute and chronic amphetamine administration on superoxide dismutase (SOD) and catalase (CAT) activity, in a rodent model of mania. Male Wistar rats received either a single IP injection of d-amphetamine (1 mg/kg, 2 mg/kg, or 4 mg/kg) or vehicle (acute treatment). In the chronic treatment rats received a daily IP injection of either d-amphetamine (1 mg/kg, 2 mg/kg, or 4 mg/kg) or vehicle for 7 days. Locomotor behavior was assessed using the open field test. SOD and CAT activities were measured in the prefrontal cortex, hippocampus, and striatum. Acute and to a greater extent chronic amphetamine treatment increased locomotor behavior and affected SOD and CAT activities in the prefrontal cortex, hippocampus and striatum. Our findings suggest that amphetamine exposure is associated with an imbalance between SOD and CAT activity in the prefrontal cortex, hippocampus and striatum.     

Structural analysis of an Echinococcus granulosus actin-fragmenting protein by small-angle x-ray scattering studies and molecular modeling

The Echinococcus granulosus actin filament-fragmenting protein (EgAFFP) is a three domain member of the gelsolin family of proteins, which is antigenic to human hosts. These proteins, formed by three or six conserved domains, are involved in the dynamic rearrangements of the cytoskeleton, being responsible for severing and capping actin filaments and promoting nucleation of actin monomers. Various structures of six domain gelsolin-related proteins have been investigated, but little information on the structure of three domain members is available. In this work, the solution structure of the three domain EgAFFP has been investigated through small-angle x-ray scattering (SAXS) studies. EgAFFP exhibits an elongated molecular shape. The radius of gyration and the maximum dimension obtained by SAXS were, respectively, 2.52 +/- 0.01 nm and 8.00 +/- 1.00 nm, both in the absence and presence of Ca2+. Two different molecular homology models were built for EgAFFP, but only one was validated through SAXS studies. The predicted structure for EgAFFP consists of three repeats of a central beta-sheet sandwiched between one short and one long alpha-helix. Possible implications of the structure of EgAFFP upon actin binding are discussed.     

Ticks (Acari: Ixodidae) associated with small terrestrial mammals in the state of Minas Gerais, southeastern Brazil

From June 2005 to November 2010, 43 small mammals encompassing 6 species of Didelphimorphia, 8 species of Rodentia, and 1 species of Lagomorpha were found parasitized by ticks in the state of Minas Gerais, southeastern Brazil. Nine tick species, in total 186 specimens, were identified as follows: Amblyomma cajennense (larvae and nymphs) on opossums and rodents; Amblyomma ovale (nymphs) on rodents; Amblyomma parvum (nymphs) on rodents; Amblyomma coelebs (nymphs) on opossums; Amblyomma dubitatum (nymph) on opossums; Ixodes amarali (females, nymphs, and larvae) on opossums and rodents; Ixodes loricatus (male, females, nymph) on opossums; Ixodes schulzei (female) on rodents; and Haemaphysalis leporispalustris (female) on rabbits. Most of the tick-host associations found in the present study have never been recorded in the literature; those include three new host records for I. amarali, four for A. cajennense, one for A. dubitatum, two for A. ovale, and one for A. coelebs. In addition, we provide the first record of A. coelebs in the state of Minas Gerais.     

Integrated versus stand-alone second generation ethanol production from sugarcane bagasse and trash

Ethanol production from lignocellulosic materials is often conceived considering independent, stand-alone production plants; in the Brazilian scenario, where part of the potential feedstock (sugarcane bagasse) for second generation ethanol production is already available at conventional first generation production plants, an integrated first and second generation production process seems to be the most obvious option. In this study stand-alone second generation ethanol production from surplus sugarcane bagasse and trash is compared with conventional first generation ethanol production from sugarcane and with integrated first and second generation; simulations were developed to represent the different technological scenarios, which provided data for economic and environmental analysis. Results show that the integrated first and second generation ethanol production process from sugarcane leads to better economic results when compared with the stand-alone plant, especially when advanced hydrolysis technologies and pentoses fermentation are included.     

Thymidylate synthase polymorphisms are associated to therapeutic outcome of advanced non-small cell lung cancer patients treated with platinum-based chemotherapy

Thymidylate synthase (TYMS) has three polymorphisms that may modulate thymidylate synthase (TS) expression levels: (1) 28 base pairs (bp) variable number tandem repeat (VNTR) (rs34743033); (2) single nucleotide polymorphism (SNP) C>G at the twelfth nucleotide of the second repeat of 3R allele (rs2853542); and (3) 6 bp sequence deletion (1494del6, rs34489327). This study was conducted to evaluate the influence of TYMS polymorphisms on the survival of Portuguese patients with advanced non-small cell lung cancer (NSCLC) undergoing platinum-based chemotherapy. Our results showed no statistically significant differences between VNTR genotypes; although, considering the SNP C>G, homozygotes 3RG presented a better prognostic at 36 months (p = 0.004) and overall survival (p = 0.003) when compared to 2R3RG patients. Patients with “median/high expression genotypes” demonstrated a better survival at 12 months (p = 0.041) when compared to “low expression genotypes”. Furthermore, 6 bp? carriers (p = 0.006) showed a better survival at 12 months when compared to 6 bp+ homozygotes patients. When analyzing TYMS haplotypes, better survival at 12 months was observed for patients carrying haplotypes with the 6 bp? allele (2R6 bp?; p = 0.026 and 3RG6 bp?; p = 0.045). This is the first report that evaluates the three major TYMS polymorphisms in the therapeutic outcome of NSCLC in Portugal. According to our results, the TYMS polymorphisms may be useful tools to predict which advanced NSCLC patients could benefit more from platinum-based chemotherapy regimens.     

Structure and mechanism of the RNA triphosphatase component of mammalian mRNA capping enzyme

The 5' capping of mammalian pre-mRNAs is initiated by RNA triphosphatase, a member of the cysteine phosphatase superfamily. Here we report the 1.65 A crystal structure of mouse RNA triphosphatase, which reveals a deep, positively charged active site pocket that can fit a 5' triphosphate end. Structural, biochemical and mutational results show that despite sharing an HCxxxxxR(S/T) motif, a phosphoenzyme intermediate and a core alpha/beta-fold with other cysteine phosphatases, the mechanism of phosphoanhydride cleavage by mammalian capping enzyme differs from that used by protein phosphatases to hydrolyze phosphomonoesters. The most significant difference is the absence of a carboxylate general acid catalyst in RNA triphosphatase. Residues conserved uniquely among the RNA phosphatase subfamily are important for function in cap formation and are likely to play a role in substrate recognition.     

The surface free energy of Leishmania mexicana amazonensis.

Surface charge of Leishmania mexicana amazonensis was investigated by direct zeta-potential determination and ultrastructural cytochemistry, and its surface tension was studied by measurements of the advancing contact angle formed by the parasite monolayers with drops of liquids of different polarities. Both virulent and avirulent promastigotes exhibited negatively charged surfaces with a zeta-potential of about -15 mV. Treatment of these cells with trypsin, alkaline phosphatase, or phospholipase C rendered their surfaces less negatively charged, whereas neuraminidase did not alter the parasite negativeness. Cytochemically, we could observe a reduction in the cationized ferritin binding after the parasite treatment with each of the former enzymes, but not with neuraminidase. The surface free energy of parasites was calculated by taken to account the London dispersion, the Keeson dipole-dipole, and the Debye dipole-induced forces, as well as the surface polarity of the parasites and their zeta-potentials, by considering their adhesion to polystyrene surfaces. The delta G values of -6.4 and -18.1 mJ.m-2 were obtained for avirulent and virulent promstigotes, respectively.     

Manihot alterniflora and M. elongata spp. nov. (Euphorbiaceae) and the rediscovery of M. quinquefolia in Caatinga (semiarid) vegetation in Brazil

We describe and illustrate two species of Manihot that occur in Caatinga (semiarid) vegetation in Brazil and redescribe and lectotypify M. quinquefolia Pohl, which was only known from a single collection made by J. E. B. Pohl in 1827. Manihot elongata P.Carvalho & M.Martins is widely distributed and Manihot alterniflora P.Carvalho & M.Martins is endangered because of its small populations and restricted area of occurrence. We establish M. quinquefolia as the only species of Manihot in the Caatinga with compound leaves. An identification key is provided for the 13 species of Manihot present in the Caatinga.