Your browser doesn't support javascript.
loading
Montrer: 20 | 50 | 100
Résultats 1 - 14 de 14
Filtre
Ajouter des filtres








Gamme d'année
1.
Mem. Inst. Oswaldo Cruz ; 99(8): 815-822, dez. 2004. ilus
Article Dans Anglais | LILACS | ID: lil-393762

Résumé

The effects of blood components, nerve-cord severance, and ecdysone therapy on the posterior midgut epithelial cells of 5th-instar Rhodnius prolixus nymphs 10 days after feeding were analyzed by transmission electron microscopy. Cutting the nerve-cord of the blood-fed insects partially reduced the development of microvilli and perimicrovillar membranes (PMM), and produced large vacuoles and small electrondense granules; insects fed on Ringer's saline diet exhibited well developed microvilli and low PMM production; swolled rough endoplasmatic reticulum and electrondense granules; Ringer's saline meal with ecdysone led to PMM development, glycogen particles, and several mitochondria in the cytoplasm; epithelial cells of the insects fed on Ringer's saline meal whose nerve-cord was severed showed heterogeneously distributed microvilli with reduced PMM production and a great quantity of mitochondria and glycogen in the cytoplasm; well developed microvilli and PMM were observed in nerve-cord severed insects fed on Ringer's saline meal with ecdysone; Ringer's saline diet containing hemoglobin recovered the release of PMM; and insects fed on human plasma showed slightly reduced PMM production, although the addition of ecdysone in the plasma led to a normal midgut ultrastructural organization. We suggest that the full development of microvilli and PMM in the epithelial cells depends on the abdominal distension in addition to ingestion of hemoglobin, and the release of ecdysone.


Sujets)
Animaux , Mâle , Sang , Ecdysone , Microvillosités , Rhodnius , Intestins , Microscopie électronique , Nymphe
2.
Mem. Inst. Oswaldo Cruz ; 94(6): 771-7, Nov.-Dec. 1999.
Article Dans Anglais | LILACS | ID: lil-251337

Résumé

Protease activities in the haemolymph and fat body in a bloodsucking insect, Rhodnius prolixus, infected with Trypanosoma rangeli, were investigated. After SDS-polyacrylamide gel electrophoresis containing gelatin as substrate, analysis of zymograms performed on samples of different tissues of controls and insects inoculated or orally infected with short or long epimastigotes of T. rangeli, demonstrated distinct patterns of protease activities: (i) proteases were detected in the haemolymph of insects which were fed on, or inoculated with, short epimastigotes of T. rangeli (39 kDa and 33 kDa, respectively), but they were not observed in the fat body taken from these insects; (ii) protease was also presented in the fat bodies derived from naive insects or controls inoculated with sterile phosphate-saline buffer (49 kDa), but it was not detected in the haemolymph of these insects; (iii) no protease activity was observed in both haemolymph and fat bodies taken from insects inoculated with, or fed on, long epimastigotes of T. rangeli. Furthermore, in short epimastigotes of T. rangeli extracts, three bands of the protease activities with apparent molecular weights of 297, 198 and 95 kDa were detected while long epimastigotes preparation presented only two bands of protease activities with molecular weights of 297 and 198 kDa. The proteases from the insect infected with T. rangeli and controls belong to the class of either metalloproteases or metal-activated enzymes since they are inhibited by 1,10-phenanthroline. The significance of these proteases in the insects infected with short epimastigotes of T. rangeli is discussed in relation to the success of the establishment of infection of these parasites in its vector, R. prolixus


Sujets)
Animaux , Vecteurs de maladies , Metalloendopeptidases/métabolisme , Rhodnius/parasitologie , Trypanosoma/enzymologie , Électrophorèse sur gel de polyacrylamide , Corps gras/enzymologie , Interactions hôte-parasite , Trypanosomiase/parasitologie
5.
Mem. Inst. Oswaldo Cruz ; 86(supl.2): 107-111, 1991.
Article Dans Anglais | LILACS | ID: lil-623951

Résumé

The effects of azadirachtin A, a tetranortriterpenoid from the neem tree Azadirachta indica J., on both development and interaction between Trypanosoma cruzi, the causative agent of Chagas' disease, and its vector Rhodnius prolixus were studied. Given through a blood meal, a dose-rsponse relationship of azadirachtin was established using antifeedant effect and ecdysis inhibition as effective parameters. A singlo dose of azadirachtin A was able to block the onset of mitosis in the epidermis and ecdysteroid titers in the hemnolymph, determined by radioimmuneassay, were too low for an induction of ecadysis. The survival of T. cruzi was also studied in R. prolixus treated with the drug. If the trypomastigotes were fed in presence of azadirachtin A the number of parasites drastically decreased. If the drug was applied after infection of the bug with T. cruzi, the parasite was still abolished from the gut. If the insect was pretreated with azadirachtin A before infection the same observation was obtained. A single dose of azadirachtin A was enough for a permanent resistance of the insect host against its reinfection with T. cruzi and for blocking the ecdysis for a long time. The effects of azadirachtin A on the hormonal balance of the host and growth inhibition of the parasite will be discussed on the basis of the present results.


Sujets)
Animaux , Vecteurs insectes/effets des médicaments et des substances chimiques , Vecteurs insectes/parasitologie , Insecticides/pharmacologie , Hormones des invertébrés/biosynthèse , Système neuroendocrinien/effets des médicaments et des substances chimiques , Trypanosoma cruzi/croissance et développement , Larve/croissance et développement
7.
Mem. Inst. Oswaldo Cruz ; 85(3): 299-304, jul.-set. 1990. tab
Article Dans Anglais | LILACS | ID: lil-93592

Résumé

Host blood source was found to affect both the development and the reproductive performance of Rhodnius prolixus. The insects were reared on citrated human, rabbit, chicken, sheep and horse blood sources, through a membrane feeder, during an entire life cycle, from eggs to adults. Development and reproduction in terms of the number of unfed insects, number of moulting, mortality intermoulting period, number of egg/female, conversion of blood into egg (mg meal/egg) and percentage of hatch as effective physiological parameters were investigated. Our results showed that human or rabbit blood meals were more nutritionally efficient than the other blood samples used because (i) the insects developed faster, presented low mortality and about 80% of them reached the adult stage; and (ii) females oviposited an average of at least 100% more eggs. The inefficiency of chicken and horse blood sources as diets for R. prolixus was manifested in (i) a decrease of the amount of ingested blood and (ii) only a reasonable nutritional quality. The inadequacy of sheep blood was observed by a mortality extremely high, poor moulting response and drastic reduction in egg production


Sujets)
Animaux , Mâle , Femelle , Comportement alimentaire , Rhodnius/physiologie , Poids , Reproduction , Rhodnius/croissance et développement
9.
Braz. j. med. biol. res ; 22(5): 597-9, 1989. tab
Article Dans Anglais | LILACS | ID: lil-73899

Résumé

Trypanosoma cruzi strain Y and clone Dm28c and other trypanosomatids were exposed to two lytic agents, Rhodnius prolixus hemolytic factor (RHF) and mellitin, in vitro. In both cases, the result was a significant decrease in the number of parasites after a 30-min treatment at 37-C. RHF and mellitin had distinct activities on differente strains and species of trypanosomatids. These observations suggest that RHF may be an important factor in selecting resistant strains of trypanosomes for development in the vector's gut


Sujets)
Animaux , Cardiotoxines de venin de cobra/pharmacologie , Techniques in vitro , Mélittine , Rhodnius , Trypanosomatina/effets des médicaments et des substances chimiques
12.
Mem. Inst. Oswaldo Cruz ; 79(4): 419-23, 1984.
Article Dans Anglais | LILACS | ID: lil-22805

Résumé

Adicionado ao sangue alimentar na dose de 25 micros/ml o precoceno II causou um aumento no periodo de intermuda em ninfas de 4o. estadio de Rhodnius prolixus. Este atraso da muda foi relacionado com a diminuicao da area dos nucleos das celulas das glandulas protoracicas e com a queda da atividade mitotica das celulas da epiderme do inseto. Um analogo de hormonio juvenil aplicado topicamente (60 micros/inseto) junto com o tratamento oral com precoceno II preveniu a atrofia das glandulas protoracicas e induziu um aumento no numero de mitoses nas celulas da epiderme, diminuindo o periodo de intermuda nestes insetos.A possivel relacao entre a acao do hormonio juvenil e a producao de ecdisona pelas glandulas protoracicas e discutida


Sujets)
Animaux , Benzopyranes , Ecdysone , Hormones juvéniles , Rhodnius
13.
Rev. AMRIGS ; 26(3): 185-91, 1982.
Article Dans Portugais | LILACS | ID: lil-8644

Résumé

Os autores apresentam sua experiencia inicial em 100 pacientes com traumatismo toracico, admitidos no Hospital Sao Vicente de Paula no periodo de agosto de 1979 a janeiro de 1981. Discutem os principios gerais no atendimento a estes pacientes,as situacoes especificas e enfatizam a necessidade de drenagem pleural adequada, da toracotomia imediata na persistencia de hemorragia e choque apesar do tratamento inicial, e que especial atencao deve ser dada as lesoes associadas, pois aqui contribuiram com 45% dos obitos de um total de 11 pacientes


Sujets)
Humains , Blessures du thorax , Drainage , Chirurgie thoracique
14.
Rev. AMRIGS ; 25(2): 118-22, 1981.
Article Dans Portugais | LILACS | ID: lil-3598

Résumé

Sao apresentados dois casos de fistula arterio-venosa apos ferimento penetrante na regiao cervico-toracica. A necessidade do diagnostico preciso e precoce, bem como a correta abordagem cirurgica nesta situacao sao discutidos


Sujets)
Fistule artérioveineuse , Artère subclavière , Plaies pénétrantes
SÉLECTION CITATIONS
Détails de la recherche