Estudo experimental sobre possível atividade da violeta de genciana na profilaxia da transmissão da toxoplasmose por transfusão de sangue

Devido a evidências sugestivas da possibilidade de transmissão da toxoplasmose por transfusão de sangue, os autores se propuseram avaliar o papel preventivo da violeta de genciana, à semelhança do que já é estabelecido para a doença de Chagas. O experimento em camundongos revelou a ação profilática da violeta de genciana quando adicionado ao sangue a ser transfundido na concentração de 1/1000 e permanência por 48 horas na geladeira.

Schistosoma mansoni: comparative evaluation of different routes of experimental infection

Experiments were carried out with Sw albino mice and it was concluded that the percutaneous route via abdominal skin was significatively more efficient than tail immersion method and subcutaneous infection; the subcutaneous injection was significatively more efficient than the percutaneous infection through the tail; this latter and the intraperitoneal injection, resulted in similar infections, but were significatively less efficient than the others. Significative difference was also observed in the comparison between the subcutaneous route and percutaneous infection through ear pinna. The influence of the site of skin infection by percutaneous route was also discussed.

Reinfecção pelo Toxoplasma gondii Nicolle & Manceaux, 1909 em camundongos e gatos: estudo experimental

A reinfecção pelo Toxoplasma gondii foi estudada, experimentalmente, em 27 camundongos albinos e 25 gatos domésticos. A infecção e a reinfecção foram comprovadas por sinais clínicos, anticorpos sangüíneos à reação de Sabin & Feldman > 1/4, recuperação do parasita e, nos gatos, também pela eliminação de oocistos. Nos camundongos a mortalidade foi de 56%. A primo-infecção por cepa de baixa virulência ou a infecção por cepa mais virulenta, atenuada pela sulfamonometoxina, deram proteção à reinfecção por cepa mais virulenta, mortal em poucos dias. Esta proteção foi demonstrada pela sobrevivência de camundongos e menor mortalidade, 12,5'%. Nos gatos a mortalidade foi de 28%, A resposta sorológica à primo-infecção ocorreu em todos. Após a reinfecção houve elevação de títulos em 64% dos gatos, permanência em 32% e queda em 4%. A eliminação de oocistos foi observada em 60% dos gatos e só após inoculação de cistos, por via digestiva. A reeliminação após reinfecção, ocorreu em 25% dos gatos. Não foi observada eliminação após a 3.ª inoculação. Em 88,2% dos gatos houve recuperação do parasita em camundongo, mais freqüente nos linfonodos mesentéricos e no intestino delgado, persistindo neste cerca de 14 meses. Foi constatada certa relação entre o bom estado físico dos gatos e a resposta sorológica, a eliminação e a reeliminação de oocistos. Apesar da persistência de anticorpos sangüíneos a reinfecção experimental dos gatos foi observada, porém a reeliminação de oocistos foi pouco freqüente e em pequena quantidade.

Ação de raios gama sobre formas sanguícolas de Trypanosoma cruzi: estudo experimental em camundongos

Amostras de sangue de animais infectados com cepa Y de Trypanosoma cruzi foram submetidas, respectivamente, a 200 e 300 krad de radiação gama. Para verificar a eficácia do método na eliminação do parasita, o material foi inoculado em camundongos e os parâmetros utilizados na avaliação foram: parasitemia, cultura, xenodiagnóstico, subinoculação, reinoculação com cepa virulenta e exame anátomo-patológico das vísceras. Os sangues expostos às duas diferentes intensidades de radiação e inoculados em dois períodos após o processo, mostraram-se inócuos quanto a capacidade de produzir infecção nos animais

Experimental infection with Schistosoma mansoni of Biomphalaria straminea from different parts of the Northeast of Brazil

In the western part of the State of Bahia Biomphalaria straminea and B. glabrata both occur, but in the majority of cases they do not share the same habitat. In the State of Ceará, however, B. straminea is the sole snail host of Schistosoma mansoni. In this survey, no naturally infected B. straminea was found among snails collected from Bahia and Ceará, evidently because of the very low infection rates. The susceptibility of laboratory-reared specimens to infection with a Puerto Rican strain of S. mansoni was then tested experimentally. In general, the snails showed very low susceptibility. The infection rates were 1.1% among snails from Redenção (Ceará); 2.3% in those from Pentecoste (Ceará); 2.9% in snails from São Desidério (Bahia), while they were very high among an albino strain (NIH) of B. glabrata used as control. Another group of B. straminea from São Desidério was exposed to a Bahian strain of S. mansoni and the infection rate was still very low (3.6%) Apparently, the very low susceptibility of B. straminea, despite high snail density, is correlated with moderate infection rates with S. mansoni among humans, as shown by the results of stool examinations conducted by SUCAM in the municipalities of Redenção and Pentecoste, in Ceará.

Malária experimental: contaminação de cepas e animais de biotério por eperythrozoon coccoides

Neste artigo descrevemos a contaminação acidental de uma cepa de malária de roedor (Plasmodium berghei) por um hemoparasita (Eperythrozoon coccoides), levando a alterações importantes no comportamento da malária experimental. A demonstração do parasita foi feita por microscopia óptica e eletrônica e a fonte de contaminação foi detectada em roedores normalmente utilizados na manutenção da cepa, obtidos do mesmo biotério. As medidas disponíveis para o controle deste tipo de infecção são discutidas propondo se a utilização de tetra-ciclina em matrizes e posterior utilização de animais Fl não tratados. Comenta-se a importância deste tipo de contaminação experimental.

Schistosoma mansoni: infecção experimental de camundongos através da orelha e quantificação do parasitismo na pele

No presente trabalho, desenvolveu-se método de infecção de camundongos através da orelha e de recuperação de esquistossômulos resultantes dessas infecções. Cerca de 80% das cercarías postas em contacto com orelhas de camundongos penetraram. Destas, 30% foram recuperadas. como vermes adultos, do sistema porta. Da pele (das orelhas) as maiores recuperações de esquistossômulos ocorreram nos dois primeiros dias após a infecção. Os parasitas permaneceram nesse sítio por dois dias. No terceiro dia, os parasitas foram recuperados tanto da pele como dos pulmões. A partir do 4.° dia, foi predominante a recuperação de esquistossômulos ao nível dos pulmões. Do total de parasitas que potencialmente atingiriam o sistema porta, proporção elevada (73-80%) pode ser recuperada da pele, no segundo dia após a infecção, como esquistossômulos. Revelando-se apropriadas ao acesso, à migração no hospedeiro e às técnicas de recuperação de parasitas, sugere-se que orelhas de camundongos podem ser utilizadas como sítio de infecção para estudos que visem a análise parasitológica dos eventos iniciais da infecção em animais normais ou imunes.

Immunoperoxidase technique in experimental chronic chagasic myocarditis

Chagas'disease has been described as the commonest form of chronic myocarditis. An immunologic pathogenesis has been discribed for this form of the disease. So far, no immunoperoxidase technique has been used for the detection of immunological deposits in chronic experimental Chagas'myocardiopathy. Forty-one Swiss mice, three months old were inoculated intraperitoneally with doses between 10 and 10(5) Tulahuen trypomastigotes. Mice were reinoculated one month after with doses between 10² and 10(5) and sacrificed at 6 (n=21) and 9 months (n=9) after the first inoculation. ECGs were recorded before sacrifice. Immunoperoxidase technique (peroxidase-antiperoxidase method), immunofluorescence (direct and indirect) as well as histological studies were performed in myocardiums and skeletal muscles of the surviving animals. The most sensitive methods for detecting chronic chagasic infection were the routine histologic studies (73%) and the ECGs 83% and 89% on 6 and 9 mo. post-infected mice, respectively. Myocardial involvement varied from interstitial mild focal lymphocyte infiltrates up to replacement of myocytes by loose connective tissue. Atrial myocardiums (21/23, 91%) were more affected than ventricles (9/23, 39%). Typical chagasic nests were rarely found. Skeletal muscle involvement (11/18 and 7/9) varied from mild to extensive lymphocyte and plasmacell infiltrates, and necrotic fibers. The involved antigen were shown in skeletal muscles by the immunoperoxidase technique as diffusely arranged granular intracytoplasmatic deposit for both IgC and total immunoglobulins. The coincidence between this technique and histologic muscle lesions was 11/18 (61(%) in 6 mo. and 6/8 (75%) at 9 mo. post-infection. In heart, delicate granular deposits of total immunoglobulins were seen diffusely arranged within the ventricular myocytes; coincidence between immunoperoxidase technique anl histologic involvement increased from 36 to 66% in animals sacrifeced 6 and 9 mo. post-infection. This strongly stressed the increase of immunologic phenomena with the chronification of infection. Concerning sensitivity, immunoperoxidase and direct immunofluorescence were highly sensitive in skeletal muscle (100%, p < 0.01). Conversely, direct immunofluorescence technique showed poor results in heart while immunoperoxidase increased its sensitivity from 21.4% (at 6 mo.) to 66.6% (at 9 mo.) post-infection (p < 0.001). Considering the necessity of obtaining an adequate vaccine in order to prevent this disease an experimental model like this, rendering immunological reactions as revealed by the immunoperoxidase technique, would be useful.

Coral snake venoms: mode of action and pathophysiology of experimental envenomation

Coral snakes, the New World Elapidae, are included in the genera Micniroides and Micrurus. The genus Mlcrurus comprises nearly all coral snake species and those which are responsible for human snake-bite accidents. The following generalizations concerning the effects induced by their venoms, and their venom-properties can be made. Coral snake venoms are neurotoxic, producing loss of muscle strenght and death by respiratory paralysis. Local edema and necrosis are not induced nor blood coagulation or hemorrhages. Proteolysis activity is absent or of very low grade. They display phospholipase A2 activity. Nephrotoxic effects are not evoked. The main toxins from elapid venoms are postsynaptic and presynaptic neurotoxins and cardiotoxins. Phospholipases A2 endowed with myonecrotic or cardiotoxin-like properties are important toxic components from some elapid venoms. The mode of action of Micrurus frontalis, M. lemniscatus, M. corallinus and M. fulvius venoms has been investigated in isolated muscle preparations and is here discussed. It is shown that while M. frontalis and M. lemniscatus venoms must contain only neurotoxins that act at the cholinergic end-plate receptor (postsynaptic neurotoxins), M. corallinus venom also inhibits evoked acetylcholine release by the motor nerve endings (presynaptic neurotoxin-like effect) and M. fulvius induces muscle fiber membrane depolarization (cardiotoxin-like effect). The effects produced by M. corallinus and M. fulvius venoms in vivo in dogs and M. frontalis venom in dogs and monkeys are also reported.

Experimental and numerical study on the evaluation of ventilation efficiency

Buildings account for 40% of total energy consumption in the European Union. The reduction of energy consumption in the buildings sector constitute an important measure needed to reduce the Union's energy dependency and greenhouse gas emissions. The Portuguese legislation incorporate this principles in order to regulate the energy performance of buildings. This energy performance should be accompanied by good conditions for the occupants of the buildings. According to EN 15251 (2007) the four factors that affect the occupant comfort in the buildings are: Indoor Air Quality (IAQ), thermal comfort, acoustics and lighting. Ventilation directly affects all except the lighting, so it is crucial to understand the performance of it. The ventilation efficiency concept therefore earn significance, because it is an attempt to quantify a parameter that can easily distinguish the different options for air diffusion in the spaces. The two indicators most internationally accepted are the Air Change Efficiency (ACE) and the Contaminant Removal Effectiveness (CRE). Nowadays with the developed of the Computational Fluid Dynamics (CFD) the behaviour of ventilation can be more easily predicted. Thirteen strategies of air diffusion were measured in a test chamber through the application of the tracer gas method, with the objective to validate the calculation by the MicroFlo module of the IES-VE software for this two indicators. The main conclusions from this work were: that the values of the numerical simulations are in agreement with experimental measurements; the value of the CRE is more dependent of the position of the contamination source, that the strategy used for the air diffusion; the ACE indicator is more appropriate for quantifying the quality of the air diffusion; the solutions to be adopted, to maximize the ventilation efficiency should be, the schemes that operate with low speeds of supply air and small differences between supply air temperature and the room temperature.

Use of saprophytic leptospira strains in the serodiagnosis of experimental leptospirosis in guinea-pigs (Cavia sp)

The efficiency of four Leptospira biflexa strains (Buenos Aires, Patoc 1, Rufino and São Paulo) as single antigen in the serodiagnosis in guinea-pigs experimentally infected with seven Leptospira interrogans serovars (canicola, grippotyphosa, hardjo, icterohaemorrhagiae, pomona, tarassovi and wolffi) was evaluated by the microscopic agglutination test. The four saprophytic strains were not able to reveal antibody titres in sera of guinea-pigs experimentally infected with Leptospira interrogans. Serological cross-reactions were observed between strains Patoc 1 and São Paulo and between serovars wolffi and hardjo.

Therapy of the experimental infection by Strongyloides venezuelensis in rats with injectable ivermectin or levamizole

For the therapy of human strongyloidiasis, are necessary effective drugs to eliminate both larvae and adult worm parasitism, which may also be used by parenteral route, to obviate the particular conditions presented by many patients. A study based on the experimental infection by Strongyloides venezuelensis in rats was done, administering injectable ivermectin or levamizole. Both drugs were shown to be active, when used in single doses of 0.2 to 0.5 mg/kg of ivermectin, or 26 mg/kg for levamizole. Ivermectin was slightly more effective as far as larval stage of the infection is concerned, and the same happened for levamisole for the adult worm stage. Promising perspectives are visualized to improve the therapy of patients with serious disseminated infection by Strongyloides stercoralis.

New recycling approaches for thermoset polymeric composite wastes – an experimental study on polyester based concrete materials filled with fibre reinforced plastic recyclates

In this study, a new waste management solution for thermoset glass fibre reinforced polymer (GFRP) based products was assessed. Mechanical recycling approach, with reduction of GFRP waste to powdered and fibrous materials was applied, and the prospective added-value of obtained recyclates was experimentally investigated as raw material for polyester based mortars. Different GFRP waste admixed mortar formulations were analyzed varying the content, between 4% up to 12% in weight, of GFRP powder and fibre mix waste. The effect of incorporation of a silane coupling agent was also assessed. Design of experiments and data treatment was accomplished through implementation of full factorial design and analysis of variance ANOVA. Added value of potential recycling solution was assessed by means of flexural and compressive loading capacity of GFRP waste admixed mortars with regard to unmodified polymer mortars. The key findings of this study showed a viable technological option for improving the quality of polyester based mortars and highlight a potential cost-effective waste management solution for thermoset composite materials in the production of sustainable concrete-polymer based products.

The computational role of short-term plasticity and the balance of excitation and inhibition in neural microcircuits: experimental and theoretical analysis

The computations performed by the brain ultimately rely on the functional connectivity between neurons embedded in complex networks. It is well known that the neuronal connections, the synapses, are plastic, i.e. the contribution of each presynaptic neuron to the firing of a postsynaptic neuron can be independently adjusted. The modulation of effective synaptic strength can occur on time scales that range from tens or hundreds of milliseconds, to tens of minutes or hours, to days, and may involve pre- and/or post-synaptic modifications. The collection of these mechanisms is generally believed to underlie learning and memory and, hence, it is fundamental to understand their consequences in the behavior of neurons.(...)

Caracterização experimental de escoamentos em canais de secção composta

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de mestre em Engenharia Civil – Perfil de Construção