Correlation between solvation of peptide-resins and solvent properties

The solvation properties of model resin and peptide-resins measured in ca. 30 solvent systems correlated better with the sum of solvent electron acceptor (AN) and electron donor (DN) numbers, in 1:1 proportion, than with other solvent polarity parameters. The high sensitivity of the (AN+DN) term to detect differentiated solvation behaviors of peptide-resins, taken as model of heterogeneous and complex solutes, seems to be in agreement with the previously proposed two-parameter model, where the sum of the Lewis acidity and Lewis basicity characters of solvent are proposed for scaling solvent effect. Besides these physicochemical aspects regarding solute-solvent interactions, important implications of this study for the solid phase peptide synthesis were also observed. Each class of peptide-resin displayed a specific salvation profile that was dependent on the amount and the nature of the resin-bound peptide sequence. Plots of resin swelling versus solvent (AN+DN) values allowed the visualization of a maximum salvation region characteristic for each class of resin. This strategy facilitates the selection of solvent systems for optimal solvation conditions of peptide chains in every step of the entire synthesis cycle. Moreover, only the AN and DN concepts allow the understanding of rules for solvation/shrinking of peptide-resins when in homogeneous or in heterogeneous mixed solvents.

Preliminary Study of the Gastric Acidity in Thoroughbred Horses at Rest after Enteral Administration of Esomeprazole Magnesium (Nexium)

The regulation of gastric secretion is of crucial importance to the equilibrium of the gastroenteric system. Despite the large number of factors involved in the causes of peptic illnesses, pH = 4 is considered the threshold between physiologic and deleterious effects of stomach acid secretion. With the aim of maintaining pH greater than 4, proton-pump inhibitors, such as esomeprazole magnesium (NEXIUM), have shown excellent results in the control of acid secretion. Aimed at examining the action of this drug in the control of pH levels of gastric secretion in thoroughbreds, a single dose of 40 or 80 mg of esomeprazole magnesium was administered daily, and pH was determined serially for 5 consecutive days. The results obtained corroborated the efficacy of esomeprazole magnesium in the control of gastric pH at both doses tested, with 100% of the mean pH being greater than 5. Moreover, no statistical difference was noted between the two doses tested.

Correction of soil acidity in the subsurface of an oxisol with sandy loam texture under no-tillage

No Rio Grande do Sul (RS), muitas áreas sob plantio direto apresentam elevada saturação por Al e baixa saturação por bases na camada de 0,10-0,20 m (subsuperfície), e isso pode diminuir a produção de grãos de culturas anuais. O objetivo do presente trabalho foi avaliar se a ocorrência de alta saturação por Al e baixa saturação por bases em subsuperfície (0,10-0,20 m), no plantio direto, pode representar um ambiente restritivo para a produção de culturas, bem como avaliar os modos de incorporação de calcário na correção da acidez do solo em subsuperfície. Para isso, foi realizado um experimento com os cultivos de soja (2005/ 2006), milho (2006/2007), trigo (2007) e soja (2007/2008), em um Latossolo Vermelho distrófico típico (Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), 2006) de textura franco arenosa, há quatro anos sob plantio direto, no município de Tupanciretã (RS). Os seis tratamentos foram: sem revolvimento com ou sem calcário; lavração com ou sem calcário; e escarificação com ou sem calcário. Aos 24 meses após a aplicação dos tratamentos e nas camadas de 0-0,05, 0,05-0,10, 0,10-0,15, 0,15-0,20 e 0,20-0,30 m, foram avaliados os valores de pH-H2O, saturação por Al e por bases. Avaliou-se a produtividade de soja (2005/2006), milho (2006/2007), trigo (2007) e soja (2007/2008). A acidez do solo em subsuperfície não alterou a produtividade das culturas quando as propriedades de acidez na camada de 0-0,10 m estavam em níveis em que não se recomenda a aplicação de calcário, segundo a CQFSRS/SC (2004). A incorporação de calcário com aração foi o modo mais eficiente de corrigir a acidez em profundidade.

Selectivity of the cyclic carbonate formation by fixation of carbon dioxide into epoxides catalyzed by Lewis bases

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Polymorphisms of Lewis and Secretor genes are related to breast cancer and metastasis in axillary lymph nodes

ABH and Lewis antigen expression has been associated with cancer development and prognosis, tumor differentiation, and metastasis. Considering that invasive ductal breast carcinoma (IDC) presents multiple molecular alterations, the aim of the present study was to determine whether the polymorphism of ABO, Lewis, and Secretor genes, as well as ABO phenotyping, could be associated with tumor differentiation and lymph nodes metastasis. Seventy-six women with IDC and 78 healthy female blood donors were submitted to ABO phenotyping/genotyping and Lewis and Secretor genotyping. Phenotyping was performed by hemagglutination and genotyping by the polymerase chain reaction with sequence-specific primers. ABO, Lewis, and Secretor genes were classified by individual single nucleotide polymorphism at sites 59, 1067, 202, and 314 of the Lewis gene, 428 of the Secretor gene, and 261 (O1 allele), 526 (O2 and B allele), and 703 (B allele). No association was found between breast cancer and ABO antigen expression (P = 0.9323) or genotype (P = 0.9356). Lewis-negative genotype was associated with IDC (P = 0.0126) but not with anatomoclinical parameters. Nonsecretor genotype was associated with axillary lymph node metastasis (P = 0.0149). In conclusion, Lewis and Secretor genotyping could be useful to predict respectively breast cancer susceptibility and axillary lymph nodes metastasis.

Decreased production of TNF-alpha by lymph node cells indicates experimental autoimmune encephalomyelitis remission in Lewis rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Migratory route of Strongyloides venezuelensis in Lewis rats: Comparison of histological analyses and PCR

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Recovery from Strongyloides venezuelensis infection in Lewis rats is associated with a strong Th2 response

P>In this study, we investigated the characteristics of the infection and subsequent immunity induced by Strongyloides venezuelensis in Lewis rats. Animals were infected with 4000 L3 of S. venezuelensis and number of eggs per gram of faeces indicated an acute phase around day 8 and a recovery phase around day 32 after infection. A strong Th2 polarization during recovery phase was ascertained by a significant increase in IgG1 and IgE compared with that in the acute period. A shift in the cytokine profile confirmed these findings. A predominant production of IFN-gamma during the acute phase was followed by IL-10 production during recovery. Together these findings show that experimental infection of Lewis rats with S. venezuelensis presents a kinetics of parasite establishment and immunity similar to that described in other models of helminthic infection.

Faecal examination and PCR to detect Strongyloides venezuelensis in experimentally infected Lewis rats

More sensitive methodologies are necessary to improve strongyloidiasis diagnosis. This study compared the sensitivities of the McMaster modified technique and polymerase chain reaction (PCR) assays, both performed in faecal samples. Lewis rats were subcutaneously infected with 4,000, 400 or 40 infective third-stage larvae, considered as high, moderate or low infection, respectively. Seven days later, they were euthanized to count adult nematodes recovered from the small intestine. Stool samples were used to count the number of eggs per gram (EPG) of faeces and to detect parasite DNA by PCR performed with a species and a genus primer pair. The sensitivity of these assays depended upon parasite burden and the primer specificity. All assays presented 100% sensitivity at the highest parasite load. In the moderate infection, EPG and PCR with the genus primer maintained 100% specificity, whereas PCR sensitivity with the species primer decreased to 77.7%. In low infection, the sensitivity was 60% for EPG, 0% for PCR with the species primer and 90% for PCR done with the genus primer. Together, these results suggest that PCR with a genus primer can be a very sensitive methodology to detect Strongyloides venezuelensisin faeces of Lewis rats infected with very low parasite burden.

Microhardness change of enamel due to bleaching with in-office bleaching gels of different acidity

Objective. The aim of this study was to assess the enamel microhardness treated with three in-office bleaching agents, containing 35% hydrogen peroxide with different acidity. Materials and methods. Bovine incisors were divided into three groups that received the following bleaching agents: Whiteness HP, Total Bleach and Opalescence Xtra. Three gel applications/10-min each, totaling 30-min of bleaching treatment, were made on the teeth and activated with a blue LED (1000 mW/470 nm) combined to a LASER (120 mW/795 nm) device (Easy Bleach-Clean Line). Vickers hardness (VH) was evaluated at baseline and after the bleaching procedure. The values of Hardness loss [HNL] (% reduction) were calculated. The two-sample t-test was used for comparison of the HNL of the three bleaching products (5% level of significance). Results. The Opalescence Xtra, which had the lowest pH value (pH = 4.30), showed a significant increase of HNL when compared with Total Bleach bleaching agent, which had the highest pH value (pH = 6.62). Conclusions. The 35% hydrogen peroxide bleaching agents resulted in a reduction in surface enamel microhardness and bleaching with the most acid agent resulted in a significant enamel hardness loss compared to the less acid agent (4.30 vs 6.62). Strategies proposed to reduce the enamel loss after bleaching treatment may include the use of daily fluoride therapy, mouth rinsing (fluoride, milk and sodium bicarbonate solution), fluoride/bicarbonate dentifrices without abrasives, do not toothbrush immediately after bleaching, fluorides and calcium add to bleaching agents.

Resistance to experimental autoimmune encephalomyelitis development in Lewis rats from a conventional animal facility

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the brain and spinal cord that is mediated by CD4+ T lymphocytes specific to myelin components. In this study we compared development of EAE in Lewis rats from two colonies, one kept in pathogen-free conditions (CEMIB colony) and the other (Botucatu colony) kept in a conventional animal facility. Female Lewis rats were immunized with 100 µl of an emulsion containing 50 µg of myelin, associated with incomplete Freund's adjuvant plus Mycobacterium butyricum. Animals were daily evaluated for clinical score and weight. CEMIB colony presented high EAE incidence with clinical scores that varied from three to four along with significant weight losses. A variable disease incidence was observed in the Botucatu colony with clinical scores not higher than one and no weight loss. Immunological and histopathological characteristics were also compared after 20 days of immunization. Significant amounts of IFN-gamma, TNF-alpha and IL-10 were induced by myelin in cultures from CEMIB animals but not from the Botucatu colony. Significantly higher levels of anti-myelin IgG1 were detected in the CEMIB colony. Clear histopathological differences were also found. Cervical spinal cord sections from CEMIB animals showed typical perivascular inflammatory foci whereas samples from the Botucatu colony showed a scanty inflammatory infiltration. Helminths were found in animals from Botucatu colony but not, as expected, in the CEMIB pathogen-free animals. As the animals maintained in a conventional animal facility developed a very discrete clinical, and histopathological EAE in comparison to the rats kept in pathogen-free conditions, we believe that environmental factors such as intestinal parasites could underlie this resistance to EAE development, supporting the applicability of the hygiene hypothesis to EAE.

Solvent free esterification reactions using Lewis acids in solid phase catalysis

A clean, efficient and fast method for esterification reactions for sterically (biodiesels) or otherwise inactive (aromatic) precursors was developed, using catalysts supported in a solid phase under solvent free conditions, and whose reactions can be promoted by MW irradiation. (c) 2006 Elsevier B.V. All rights reserved.

Sources of atmospheric acidity in an agricultural-industrial region of São Paulo State, Brazil

[1] Surface-based measurements of atmospheric formic acid (HCOOH), acetic acid (CH3COOH), sulfur dioxide (SO2), hydrogen chloride (HCl), and nitric acid (HNO3) were made in central São Paulo State, Brazil, between April 1999 and March 2000. Mean concentrations were 9.0 ppb (HCOOH), 1.3 ppb (CH3COOH), 4.9 ppb (SO2), 0.3 ppb (HCl), and 0.5 ppb (HNO3). Concentrations in sugar cane burning plumes were 1160-4230 ppb (HCOOH), 360-1750 ppb (CH3COOH), 10-630 ppb (SO2), 4-210 ppb (HCl), and 14-90 ppb (HNO3). Higher ambient concentrations of SO2, HCl and HNO3 were measured during the burning season (May-November). Concentrations of SO2 and HCl increased during the evening, and of HCOOH and CH3COOH were lowest in the morning, with peak levels in the afternoon. Ratios obtained between different species showed either nighttime maxima (SO2/HCOOH, SO2/CH3COOH, SO2/HNO3, CH3COOH/HNO3, SO2/HCl and HCOOH/HNO3), daytime maxima (HCOOH/HCl, CH3COOH/HCl and HNO3/HCl), or no clear trends (HCOOH/CH3COOH). Correlation analysis showed that SO2 and HCl were primary emissions from biomass burning and road transport; HCOOH, HNO3 and CH3COOH were products of photochemistry; HCOOH and CH3COOH were emitted directly during combustion as well as from biogenic sources. Biomass burning affected atmospheric acidity on a regional scale, while vehicular emissions had greater impact in urban and adjacent areas. Atmospheric ammonia levels were insufficient to neutralize atmospheric acidity, which was mainly removed by deposition to the surface.