Binding of Sulpiride to Seric Albumins

The aim of this work was to study the interaction of sulpiride with human serum albumin (HSA) and bovine serum albumin (BSA) through the fluorescence quenching technique. As sulpiride molecules emit fluorescence, we have developed a simple mathematical model to discriminate the quencher fluorescence from the albumin fluorescence in the solution where they interact. Sulpiride is an antipsychotic used in the treatment of several psychiatric disorders. We selectively excited the fluorescence of tryptophan residues with 290 nm wavelength and observed the quenching by titrating HSA and BSA solutions with sulpiride. Stern-Volmer graphs were plotted and quenching constants were estimated. Results showed that sulpiride form complexes with both albumins. Estimated association constants for the interaction sulpiride–HSA were 2.20 (±0.08) × 10⁴ M⁻¹, at 37 °C, and 5.46 (±0.20) × 10⁴ M⁻¹, at 25 °C. Those for the interaction sulpiride-BSA are 0.44 (±0.01) × 10⁴ M⁻¹, at 37 °C and 2.17 (±0.04) × 10⁴ M⁻¹, at 25 °C. The quenching intensity of BSA, which contains two tryptophan residues in the peptide chain, was found to be higher than that of HSA, what suggests that the primary binding site for sulpiride in albumin should be located next to the sub domain IB of the protein structure.     

Pd-, Ni-, Fe-, and Co-Catalyzed Cross-Couplings Using Functionalized Zn-, Mg-, Fe-, and In-Organometallics

The development of new methods for preparing polyfunctional organometallics has made a broad range of such reagents available for various transition metal-catalyzed cross-couplings. An overview of the most general preparation methods will be presented. Applications to practical cross-coupling procedures will be covered, emphasizing the functional group compatibility and the reaction scope.     

Brazilian isolates of Trypanosoma cruzi from humans and triatomines classified into two lineages using mini-exon and ribosomal RNA sequences

Traditional molecular and biochemical methods, such as schizodeme analysis, karyotyping, DNA fingerprinting, and enzyme electrophoretic profiles, have shown a large variability among Trypanosoma cruzi isolates. In contrast to those results, polymerase chain reaction (PCR) amplification of sequences from the 24S alpha ribosomal RNA gene and from the mini-exon gene nontranscribed spacer indicated a dimorphism among T. cruzi isolates, which enabled the definition of two major parasite lineages. In the present study, 86 T. cruzi field stocks (68 isolated from humans with defined presentations of Chagas' disease and 18 from triatomines) derived from four Brazilian geographic areas were typed by the PCR assay based on the DNA sequences of the mini-exon and 24S alpha rRNA genes. These stocks were ordered into the two major T. cruzi lineages. Lineage 1 was associated mainly with human isolates and lineage 2 with the sylvatic cycle of the parasite.     

Use of poly(3‐hydroxybutyrate)/niobium oxyhydroxide nanocomposites in photocatalysis: Effect of preparation methods

In this work, nanocomposites were obtained by the dispersion of niobium oxyhydroxide into a poly(3‐hydroxybutyrate) (PHB) matrix by different preparative methods. These methods led to changes in the polymer morphology and in their photocatalytic properties. Thermal and structural properties of the nanocomposites were investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR)–attenuated total reflection (ATR). Scanning electron microscopy images were analyzed in order to observe the different morphologies of nanocomposites as well as the distribution of niobium nanoparticles in the PHB matrix. The chemical interactions between the polymer and niobium nanoparticles were observed in the FTIR–ATR and thermal analyses. The results of TGA and DSC indicated an improvement in the thermal stability of the polymer and the action of inorganic nanoparticles as nucleating agents in the process of heterogeneous nucleation of PHB. The composites exhibited good catalytic activity for the removal of methylene blue dye from an aqueous medium (～90%) during a photocatalytic process. The different morphologies of PHB/niobium oxyhydroxide composites directly influenced the catalytic activity of the material due to the difference in the dispersion of nanoparticles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45836.     

Current prospects of specific treatment of Chagas' disease

The evolution of the specific treatment of Chagas' disease, including the numerous drugs tested, is briefly summarized. Since 1969 laboratory and clinical studies have persistently demonstrated that nifurtimox (NFX) and benznidazole (BNL) are the best agents for treating Trypanosoma cruzi human infection, even though they cannot be considered ideal drugs. The main indications for NFX and BNL are: acute phase of the infection, congenital form, reactivation associated with immunosuppression, recently acquired infection, mostly in children and young adults, and in transfusions and organ transplant situations. Both drugs may also be indicated for the treatment of some patients in the undetermined asymptomatic form of the chronic infection with mild heart involvement, or in clinical megaesophagus patients who previously need symptomatic treatment to ensure the appropriate absorption of the medication. The most used dosage schedules are: NFX for 60-90 days, 8-10 mg/kg/day in adults and < 15 mg/kg/day in children. BNL, for 60 days, 5 mg/kg/day in adults and < 10 mg/kg/day in children. Both drugs are taken orally and must be given divided into 2-3 fractions after meals. Both drugs are well tolerated by children, and particularly in the acute phase of the disease. Adverse reactions may be observed, i.e. disturbances associated to the digestive tract such as hyporexia, nausea, vomiting and loss of weight with NFX, and dermopathy and polyneuropathy, with BNL. The main limitations of both drugs are in the long course of administration and the occurrence of adverse side effects. A series of promising new drugs for the treatment of human Chagas' disease is being tested. Because the relative lack of interest of the pharmaceutical industry in the research for new drugs for the treatment of the parasitosis--which affects 16-18 million people in Latin America--Universities and Research Governmental Institution should stimulate the investigation for the development of new drugs and the clinical evaluation of drugs experimentally known and not yet tested.     

Quantum-efficiency enhancement of CMOS photodiodes by deliberate violation of design rules

In this paper we propose and experimentally prove that the quantum efficiency of CMOS-compatible photodiodes can be improved in any standard process at no additional complexity, cost or surface area. The improvement is obtained by slightly boosting the drift component with respect to the diffusion component of the photogenerated current by means of an increase in the p-n junction effective area, and consequently in the volume of the depletion layer. This is accomplished by texturing the junction profile, which is realized when we intentionally violate the design rules that dictate the minimum distance between supposedly independent diffusion or implanted regions, and when we use the gate-oxide mask accordingly. To form a composite photodiode these closer bordering regions partially merge due to lateral diffusion that expand further under the boundaries of the respective photomask definitions throughout the overall thermal cycle in the process. Several characteristics of different process generations are discussed. We achieved 4% measured efficiency gain in an n-well/p-epi textured structure compared to a p+/n-well/p-epi conventionally flat photodiode. A quantum efficiency gain of at least 18% can be inferred, from an artifactual test, between textured and flat n-well/p-epi junctions.     

A bandwidth scalable OFDM passive optical network for future access network

In order to reduce the cost for delivering the ever increasing broadband services, network providers need to simplify their network architectures and have a better control of the bandwidth. In this article, we propose a simple and cost-effective bandwidth scalable passive optical network (PON) based on orthogonal frequency division multiplexing (BSOFDM-PON). We report performance analysis in terms of the signal-to-noise ratio (SNR), bit-error-rate (BER), and error vector magnitude (EVM) of a PON system accommodating 32 optical network units (ONUs). Our simulations have successfully demonstrated that throughputs of 35.5 and 53.2 Gbps can be achieved using 16 and 64 QAM, respectively, within a total distance ranging from 20 to 30 km. It gives throughputs of 1.10 and 1.66 Gbps per ONU.     

Evaluation of three commercial enzyme-linked immunosorbent assays for diagnosis of Chagas' disease

Chagas' disease is a common cause of morbidity in Latin American countries. In Brazil, naturally occurring transmission of its etiologic agent, Trypanosoma cruzi, has been almost completely abolished through effective control programs aimed at the triatomid insect vector. Thus, transfusion of blood from infected donors has become the major route for contracting Chagas' disease due to the socioeconomically motivated migration of residents from areas where the disease is endemic to the larger urban centers. Therefore, the employment of screening tests is mandatory for all blood banks throughout the country. We compared the diagnostic performances of three commercially available screening assays used in routine testing in Brazilian blood banks: the Abbott Chagas antibody enzyme immunoassay (Abbott Laboratórios do Brasil, S?o Paulo), the BIOELISACRUZI kit (Biolab-Mérieux, Rio de Janeiro, Brazil), and the BIOZIMA Chagas kit (Polychaco S.A.I.C., Buenos Aires, Argentina). The evaluation was performed with sera obtained from chagasic patients and healthy residents of four different areas in Brazil where Chagas' disease is either endemic or emergent and where clinical manifestations of the disease and circulating parasite strains vary. The results obtained with each kit were compared to matched in-house enzyme-linked immunosorbent assay and immunofluorescence assay data obtained for each sample. Depending on the area under investigation, the three commercial kits produced specificity values between 93.3 and 100.0%, sensitivity values between 97.7 and 100%, and accuracies ranging from 93.6 to 100.0%.     

Effect of Lignin Carbohydrate Complexes of Hardwood Hybrids on the Kraft Pulping Process

Lignin-carbohydrates complexes influence many chemical properties in the wood, such as difficult-to-remove lignin from Kraft pulps at the end of pulping due to the occurrence of lignin carbohydrates bonds. Therefore, this study aimed to study the influence of lignin-carbohydrate complexes on eucalyptus Kraft pulping. Spectroscopic techniques (¹³C NMR and HSQC-2D) were applied for the determination and quantification of lignin-carbohydrate complex (LCC) structures, and then evaluated the effect of LCC on Kraft pulping of eucalyptus hybrids. The analytical tools allowed the identification and quantification of the benzyl ether, γ-ester, and phenyl glucoside linkages of the lignin-carbohydrate complexes in eucalyptus hybrid wood. The glycosidic phenyl and γ-ester linkages are, respectively, more and less significant from the quantitative point of view. Analysis of ¹³C NMR of the samples showed that the eucalyptus hybrid GxGL contained high β-O-4 linkages content and also higher pulping yield than the other samples, suggesting that the linkages between lignin are more important than LCC linkages in pulping.