Effect of selective phosphodiesterase inhibitors on the rat eosinophil chemotactic response in vitro

In the present study, we have performed a comparative analysis of the effect of selective inhibitors of phosphodiesterase (PDE) type III, IV and V on eosinophil chemotaxis triggered by platelet activating factor (PAF) and leukotriene B4 (LTB4) in vitro. The effect of the analogues N6-2'-O-dibutyryladenosine 3':5' cyclic monophosphate (Bt2 cyclic AMP) and N2-2'-O- dibutyrylguanosine 3':5' cyclic monophosphate (Bt2 cyclic GMP) has also been determined. The eosinophils were obtained from the peritoneal cavity of naive Wistar rats and purified in discontinuous Percoll gradients to 85-95% purity. We observed that pre-incubation of eosinophils with the PDE type IV inhibitor rolipram suppressed the chemotactic response triggered by PAF and LTB4, in association with an increase in the intracellular levels of cyclic AMP. In contrast, neither zaprinast (type V inhibitor) nor type III inhibitors milrinone and SK&F 94836 affected the eosinophil migration. Only at the highest concentration tested did the analogue Bt2 cyclic AMP suppress the eosinophil chemotaxis, under conditions where Bt2 cyclic GMP was ineffective. We have concluded that inhibition of PDE IV, but not PDE III or V, was able to block the eosinophil chemotaxis in vitro, suggesting that the suppressive activity of selective PDE IV inhibitors on tissue eosinophil accumulation may, at least, be partially dependent on their ability to directly inhibit the eosinophil migration.

Experimental evidence and ecological perspectives for the adaptation of Schistosoma mansoni Sambon, 1907 (Digenea: Schistosomatidae) to a wild host, the water-rat, Nectomys squamipes Brants, 1827 (Rodentia: Sigmodontinae)

Due to the semi aquatic habits and the overlap of the geographical distribution of the water-rat, Nectomys spp., with schistosomiasis endemic areas, these wild rodents are very likely to acquire Schistosoma mansoni infection in their daily activities. The role of the water-rat in the S. mansoni cycle would be substantiated if one could prove that these rodents acquire the parasite during their own activity time, a completely independent time schedule of human activities. To pursue this goal, we performed two field experiments in the municipality of Sumidouro, State of Rio de Janeiro, Brazil, a schistosomiasis endemic area where N. squamipes is found naturally infected. One experiment was devised as a series of observations of activity time of the water-rat. The other experiment was a test of the occurrence of late transmission of S. mansoni to the water-rat. The daily activity pattern showed that the water-rat is active chiefly just after sunset. At both diurnal and late exposition essays the water-rat sentinels got infected by S. mansoni. These findings clarify ecological and behavioral components necessary to the adaptation of S. mansoni to the water-rat as a non human definitive host and the existence of a transmission cycle involving this animals as a reservoir.

An ecological field study of the water-rat Nectomys squamipes as a wild reservoir indicator of Schistosoma mansoni transmission in an endemic area

Small mammals are found naturally infected by Schistosoma mansoni, becoming a confounding factor for control programs of schistosomiasis in endemic areas. The aims of this study were: to investigate the infection rates by S. mansoni on the water-rat Nectomys squamipes during four years in endemic areas of Sumidouro, state of Rio de Janeiro, using mark-recapture technique; to compare two diagnostic methods for schistosomiasis; and to evaluate the effects of the chemotherapy in the human infected population on the rodent infection rates. The rodent infection rates of S. mansoni increased when rodent population sizes were lower. Coprology and serology results presented the same trends along time and were correlated. Serology could detect recent infection, including the false negatives in the coprology. The chemotherapy in the humans could not interrupt the rodent infection. Rodents can increase the schistosomiaisis transmission where it already exists, they probably maintain the transmission cycle in the nature and can be considered as biological indicators of the transmission sites of this parasite since they are highly susceptible to infection. The water-rats may present different levels of importance in the transmission dynamics of S. mansoni infection cycle for each area, and can be considered important wild-reservoirs of this human disease.

Benznidazole biotransformation in rat heart microsomal fraction without observable ultrastructural alterations: comparison to Nifurtimox-induced cardiac effects

Benznidazole (Bz) and Nifurtimox (Nfx) have been used to treat Chagas disease. As recent studies have de-monstrated cardiotoxic effects of Nfx, we attempted to determine whether Bz behaves similarly. Bz reached the heart tissue of male rats after intragastric administration. No cytosolic Bz nitroreductases were detected, although microsomal NADPH-dependent Bz nitroreductase activity was observed, and appeared to be mediated by P450 reductase. No ultrastructurally observable deleterious effects of Bz were detected, in contrast to the overt cardiac effects previously reported for Nfx. In conclusion, when these drugs are used in chagasic patients, Bz may pose a lesser risk to heart function than Nfx when any cardiopathy is present.

Larval recovery of Toxocara cati in experimentally infected Rattus norvegicus and analysis of the rat as potential reservoir for this ascarid

Toxocara cati is a common feline parasite transmitted by the ingestion of embryonated eggs, by the transmammary route or by predation of paratenic hosts harbouring third-stage larvae in their bodies. In the present study, the larval distribution of T. cati in tissues and organs of Rattus norvegicus experimentally infected with 300 embryonated eggs was analysed. Third-stage larvae were recovered from livers, lungs, kidneys, eyes, brains and carcasses of infected rats, following tissue digestion with HCl 0.5% for 24 h at 37°C. Some differences from the known larval distribution of Toxocara canisin the same rodent species were found.

Infection in a rat model reactivates attenuated virulence after long-term axenic culture of Acanthamoeba spp

Prolonged culturing of many microorganisms leads to the loss of virulence and a reduction of their infective capacity. However, little is known about the changes in the pathogenic strains of Acanthamoeba after long culture periods. Our study evaluated the effect of prolonged culturing on the invasiveness of different isolates of Acanthamoeba in an in vivo rat model. ATCC strains of Acanthamoeba, isolates from the environment and clinical cases were evaluated. The in vivo model was effective in establishing the infection and differentiating the pathogenicity of the isolates and re-isolates. The amoebae cultured in the laboratory for long periods were less virulent than those that were recently isolated, confirming the importance of passing Acanthamoeba strains in animal models.

A randomised double-blind clinical trial of two yellow fever vaccines prepared with substrains 17DD and 17D-213/77 in children nine-23 months old

This randomised, double-blind, multicentre study with children nine-23 months old evaluated the immunogenicity of yellow fever (YF) vaccines prepared with substrains 17DD and 17D-213/77. YF antibodies were tittered before and 30 or more days after vaccination. Seropositivity and seroconversion were analysed according to the maternal serological status and the collaborating centre. A total of 1,966 children were randomised in the municipalities of the states of Mato Grosso do Sul, Minas Gerais and São Paulo and blood samples were collected from 1,714 mothers. Seropositivity was observed in 78.6% of mothers and 8.9% of children before vaccination. After vaccination, seropositivity rates of 81.9% and 83.2%, seroconversion rates of 84.8% and 85.8% and rates of a four-fold increase over the pre-vaccination titre of 77.6% and 81.8% were observed in the 17D-213/77 and 17DD subgroups, respectively. There was no association with maternal immunity. Among children aged 12 months or older, the seroconversion rates of 69% were associated with concomitant vaccination against measles, mumps and rubella. The data were not conclusive regarding the interference of maternal immunity in the immune response to the YF vaccine, but they suggest interference from other vaccines. The failures in seroconversion after vaccination support the recommendation of a booster dose in children within 10 years of the first dose.

Usage of Calendula officinalis in the prevention and treatment of radiodermatitis: a randomized double-blind controlled clinical trial

OBJECTIVE To evaluate the efficacy of Calendula officinalis in relation to Essential Fatty Acids for the prevention and treatment of radiodermatitis. METHOD This is a randomized double-blind controlled clinical trial with 51 patients with head and neck cancer in radiotherapy treatment divided into two groups: control (27) and experimental (24). RESULTS There is statistically significant evidence (p-value = 0.0120) that the proportion of radiodermatitis grade 2 in Essential Fatty Acids group is higher than Calendula group. Through the Kaplan-Meier survival curve we observed that Essential Fatty Acids group has always remained below the Calendula group survival curve, due to the lower risk of developing radiodermatitis grade 1, which makes the usage of Calendula more effective, with statistical significance (p-value = 0.00402). CONCLUSION Calendula showed better therapeutic response than the Essential Fatty Acids in the prevention and treatment of radiodermatitis. Brazilian Registry of Clinical Trials: RBR-237v4b.

Antagonismo direto e biocontrole da podridão-mole-do-tomateiro pelo uso de procariotas

O objetivo deste trabalho foi avaliar procariotas quanto ao potencial de antagonismo direto para o biocontrole da podridão-mole-do-tomateiro (Pectobacterium carotovorum subsp. carotovorum). Avaliaram-se 45 isolados bacterianos pelo teste de antibiose contra o patógeno. Foram feitos dois ensaios em que sementes de tomate (Lycopersicon esculentum Mill.) cv. Santa Clara foram infectadas com isolados antagônicos. As mudas foram transplantadas para solos infestados com suspensões de propágulos P. carotovorum com OD540 de 0,45 e 0,65. Os antagonistas UFV-0005, UFV-043, UFV-BF112 e UFV-0006 foram eficientes em proteger plantas de tomateiro contra a podridão-mole.

Atividade antioxidante in vitro e in vivo de café bebida mole

O objetivo deste trabalho foi determinar a atividade antioxidante do café, bebida mole, in vivo e in vitro, antes e após a torração. Para a análise da atividade antioxidante in vitro, foram utilizados os métodos de sequestro de radicais livres (DPPH) e de atividade quelante de íons Fe2+. Foram utilizados, para o ensaio in vivo, ratos Zucker diabéticos, portadores de síndrome metabólica, e ratos Zucker controle. Os animais receberam doses diárias das bebidas de café, por gavagem, por 30 dias. Após o tratamento, foi realizada a avaliação de peroxidação lipídica. As amostras torradas apresentaram a maior percentagem de sequestro de radicais livres. As concentrações nas amostras de café verde e torrado foram similares às do padrão Trolox. Das amostras torradas, a torração média se destacou com maior atividade quelante de íons Fe2+. Os cafés verdes mostraram maior poder quelante do que os torrados. Compostos presentes no extrato diminuíram a lipoperoxidação hepática e renal que é comum em casos de diabetes e síndrome metabólica. O café apresenta atividade antioxidante e protege o fígado e os rins dos animais contra a lipoperoxidação comumente presente em quadros de diabetes mellitus tipo 2 e síndrome metabólica.

Alternativas de controle pós-colheita da podridão-parda e da podridão-mole em frutos de pessegueiro

As exigências do consumidor são cada vez maiores com relação à qualidade de produtos in natura. As podridões, além de causar perdas na produção, reduzem a qualidade final do fruto, interferindo significativamente na comercialização. Objetivou-se, com este trabalho, avaliar a eficiência de produtos alternativos, aplicados na pós-colheita, no controle da podridão-parda (Monilinia fructicola) e da podridão-mole (Rhizopus spp.) em pêssegos. O experimento foi conduzido no município de Nepomuceno-MG, em talhão de pessegueiro da cultivar Diamante, com 10 anos de idade. O delineamento experimental utilizado foi o inteiramente casualizado, com 7 tratamentos e 3 repetições. Para o estudo, foram selecionados frutos sem lesões e sem sintomas das doenças. Os frutos foram mergulhados por 30 segundos em solução contendo os seguintes tratamentos: 1-Óleo de cravo 0,01%; 2-Dióxido de cloro 0,1%; 3-Dióxido de cloro 0,05%; 4-Cloreto de benzalcônio 0,25%; 5-Dicloran 0,12%; 6-Iprodione 0,15% e 7-Testemunha (somente água). Após os tratamentos, os frutos, em número de 10, foram colocados em bandejas esterilizadas, em três repetições. O experimento foi conduzido em condições de ambiente não controlado, sendo feitas avaliações do desenvolvimento das doenças aos 3 e aos 5 dias após os tratamentos em 2005 e aos 3; 6 e aos 9 dias após o tratamento em 2006. O iprodione controlou a incidência e a severidade de M. fructicola e Rhizopus spp. O dicloran foi o tratamento mais eficiente para o controle do Rhizopus spp. e intermediário para M. fructicola. Os tratamentos com óleo de cravo e dióxido de cloro, na maior dose, reduziram a incidência de Rhizopus spp. e para severidade apresentaram resultados intermediários.

High performance liquid chromatography method for quantification of the N-phenylpiperazine derivative LASSBio-579 in rat plasma

A rapid HPLC analytical method was developed and validated for the determination of the N-phenylpiperazine derivative LASSBio-579in plasma rat. Analyses were performed using a C18 column and elution with 20 mM sodium dihydrogen phosphate monohydrate - methanol. The analyte was monitored using a photodiode array detector (257 nm). Calibration curves in spiked plasma were linear over the concentration range of 0.3-8 mg/mL with determination coefficient > 0.99. The lower limit of quantification was 0.3 mg/mL. The applicability of the HPLC method for pharmacokinetic studies was tested using plasma samples obtained after administration of LASSBio-579 to Wistar rats, showing the specificity of the method.

Sensitive method for determination of piplartine, an alkaloid amide from Piper species, in rat plasma samples by liquid chromatography-tandem mass spectrometry

Piplartine (PPTN) is an alkaloid amide found in Piper species that presents different activities. PPTN determination in rat plasma is necessary to better understand its biological effects. The aim of this study was to develop a sensitive LC-MS/MS method for the determination of PPTN in rat plasma. The performance criteria for linearity, sensitivity, precision, accuracy, recovery, and stability have been assessed and were within the recommended guidelines. The validated method proved to be suitable in a pilot study of PPTN kinetic disposition in rat plasma after a single intraperitoneal dose, and represents an appropriate tool to further pharmacokinetic studies.

Reação de cultivares de batata à podridão mole causada por Pectobacterium carotovorum subsp. atrosepticum, por P. carotovorum subsp. carotovorum e por P. chrysanthemi

A podridão mole em tubérculos de batata (Solanum tuberosum), causada por Pectobacterium carotovorum subsp. atrosepticum, por Pectobacterium carotovorum subsp. carotovorum e por P. chrysanthemi, é uma preocupante doença que causa danos expressivos à cultura em todo o mundo. Como inexiste tratamento eficiente para a podridão mole, o desenvolvimento de cultivares resistentes é considerado o método mais eficaz para a redução de perdas causadas pela doença. Nesse sentido, quatro cultivares de batata foram avaliados quanto à resistência natural às pectobactérias, mediante redução de massa de tubérculos após 20, 24, 48, 72 e 96 h de inoculação com suspensões bacterianas. O delineamento experimental constou de um esquema fatorial com quatro cultivares, três bactérias e quatro repetições. Os resultados foram transformados em proporção e integralizados como área abaixo da curva de progresso da doença (AACPD). Para as três bactérias estudadas, a cultivar Asterix mostrou-se o menos suscetível à podridão mole, diferindo significativamente dos demais.