441 resultados para Cracked eggs


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Adult cohorts and immature stages were kept under field conditions during the autumn and winter of three consecutive years. Survival, oviposition and development time from egg to adult were considered. The adult cohorts were studied under three experimental conditions: unfed cohorts, cohorts fed with sugar solution ansd cohorts fed with both sugar solution and blood (chicken). Female longevity showed significant differences among the three treatments. Females of unfed cohorts lived up to three weeks; females fed with sugar solution survived until six weeks, while those fed both with sugar and blood lived at most fourteen weeks; after the blood intake eggs were laid. In the immature stages, the highest relative mortality rates occurred during the egg and larval stages. Total pre-adult mortality varied between 59.09 and 89.71%. The developmental duration from egg to adult was between 43-62 days; there were no differences among results obtained for the three years.

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In this study, the results obtained in a control programme of schistosomiasis in Ravena (Sabará, Minas Gerais) between 1980 and 1992 are evaluated. Control measures used in this programme were: specific treatment of the people infected with Schistosoma mansoni at four year-intervals (1980/84/88) and the supply of tap water to 90% of the residences in 1980. A significant reduction of the prevalence (36.7% to 11.5%, p < 0.05) and of the intensity of the infection (228.9 eggs per gram of feces (epg), s = 3.7 to 60.3 epg, s = 3.5, p < 0.05) was observed. No cases of the severe form of the disease were diagnosed in the area. Factors independently associated with the infection were in 1980 daily sand extraction and the lack of tap water in residences and in 1992 daily sand extraction and fishing and weekly swimming. Concluding, the supply of tap water together with quadrennial treatments significantly diminished both the prevalence and intensity of the S. mansoni infection, with the additional gain of persistent low indices even after four-year intervals between the treatments.

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In Abedus ovatus Stal, the female reproductive system consists of a pair of ovaries leading to oviduct and opens out by genital aperture. Each ovary is composed of five telotrophic ovarioles, with four different regions, terminal filament, germarium, vitellarium and pedicel. Germarium and vitellarium are the germ tubes in which the development of oocyte occurs. In the germarium, the differentiation of trophocytes into young oocytes was observed in three zones, ZI, ZII and ZIII. Further development of oocytes in the vitellarium could be divided into seven stages, STI STVII. The developed eggs are lodged in the pedicel

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Eggs of two species belonging to the Arribalzagia Series of the Laticorn Section of Anopheles (Anopheles) collected in Brazil are described from scanning electron micrographs. The An. fluminensis egg is long with shallow floats displaced far dorsally. The narrow deck region is overlain by a frill modified into prominent ridges that are nearly continuous to both ends of the egg. Slightly opened decks at both poles contain an average of four lobed tubercles. Polygonal, plastron-type chorionic cells cover the lateral and dorsal surfaces. The egg of An. shannoni is unique in possessing 22-27 fingerlike filaments that project with regular spacing from each of its massive floats. These filaments and their bases are highly perforated and are believed to trap air and support flotation of the egg with the dorsal surface up, contrary to the usual orientation for anophelines. The eggs are compared with those of related species bearing similar structures, notably An. fluminensis with An. mediopunctatus s.s and An. shannoni with An. peryassui

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Biology of Triatoma pseudomaculata Corrêa & Espínola, 1964, under Laboratory Conditions (Hemiptera:Reduviidae:Triatominae) - Observations were made on the evolutive cycle of Triatoma pseudomaculata, held under laboratory conditions, fed weekly on bird (pigeon). Of 60 eggs obtained, only 34 nymphs reached the adult stage in a period of X(S)=398±76 days. The following parameters were observed: the time immature stages took to develop from egg to adult emergence; the occurrence of the first meal; the time-lapse between the presenting of the blood-meal and the begining of feeding; time of feeding; amount of blood ingested; variation of weight 24 hr after the blood-meal and until the next blood-meal; and the defecation pattern. The experiment was carried out for 20 months, held in BOD incubator with the average of temperature and humidity of 28±1ºC and 80±5% RU, respectively

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Observations were carried out on the reproductive behavior of Synthesiomyia nudiseta females. The results of the biological parameters were: pre-oviposition period (15.5 ± 4.7 days), oviposition period (25.4 ± 14.7 days), number of eggs per oviposition (95.9 ± 18.4) rate of ovipositant females (97.5%), number of ovipositions (5.31 ± 3.2), number of eggs per females (509.7 ± 324.9), rate of hatching (68.0 ± 19.0), female longevity (53.2 ± 14.7 days), reproductive potential (67.4%) and reproductive investiment (4.1).

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To compare the epidemiological profile and socioeconomic factors associated to the infection by Schistosoma mansoni in a rural and an urban endemic area a cross-sectional study was performed in Água Branca de Minas (rural area) and Bela Fama (urban area), both situated in the State of Minas Gerais, Brazil. Two hundred and eighty eight individuals were surveyed in the rural area and 787 in the urban area. Water contact and socioeconomic questionnaires were used to identify risk factors for the infection. The prevalences of 38.8% and 9.7% and the geometric mean of eggs per gram of faeces of 117.8 and 62.3 were found in the rural and urban areas, respectively. By multivariate statistical analysis age groups over nine years old and previous specific treatment were associated with the infection in rural area. In urban area age over nine years old, low quality housing, weekly fishing and swimming were associated after adjustment by logistic regression

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Schistosomiasis is a disease whose pathology is strongly related to the granulomatous reaction formed around parasite eggs trapped in host tissues. Studies have shown that the chronic intestinal form (INT) of this infection is associated with a variety of immunoregulatory mechanisms which lead to a diminished granulomatous reaction. Using an in vitro model of granuloma reaction, we show that immune complexes (IC) isolated from sera of INT patients are able to reduce granulomatous reaction developed by peripheral blood mononuclear cells (PBMC) from acute (AC), INT and hepatosplenic (HE) patients to soluble egg antigen (SEA)-conjugated polyacrylamide beads (PB-SEA). This inhibitory activity is also observed in cell proliferation assay of PBMC from INT and HE patients stimulated with SEA and adult worm antigen (SWAP). Furthermore, IC isolated from sera of patients with different clinical forms of the disease are also able to suppress INT patients PBMC reactivity. Therefore, our results show that circulating IC present in sera of patients with different clinical forms of schistosomiasis may down-regulate PBMC reactivity to parasite antigens resulting in a diminished granuloma reaction to parasite eggs

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Administration of an antifibrotic agent as an adjunct to antihelmintic treatment with the objective of morbidity reduction was investigated in the murine schistosomiasis mansoni model. Antifibrotic, ß-aminopropionitrile treatment has a profound effect on the cellular matrix composition of the liver granuloma of Schistosoma mansoni infected mice when given alone, resulting in increase macrophage infiltration. These macrophages, in response to stimulation with soluble egg antigen or lipopolysaccharide produced elevated levels of nitric oxide but low levels of tumor necrosis factor alpha compared to untreated infected mice. This also correlated with reduced liver granuloma size. In spite of low numbers of eggs in the liver, mice receiving a combine treatment had a high level of resistance to a challenge infection compared with mice receiving only praziquantel. Those mice also exhibited a reduced lymphocyte proliferative response, similar to that of infected untreated mice. Antifibrotic treatment has an impact on the dynamic of the cellular nature of granulomas and impacts on the host immunity to infection

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Pathogenesis of schistosomal hepatic fibrosis ("pipestem" fibrosis of the liver) was investigated by means of the murine model. Although worm load appears as the main pathogenetic factor, alone it is not sufficient to produce that characteristic lesion. By comparing the findings in animals with heavy and prolonged Schistosoma mansoni infection, which developed or not" pipestem" fibrosis, it was observed that the lesion was more frequent in intact animals than in the splenectomized one. However, the size of the spleen, the number of recovered worms, the number of eggs per gram of liver tissue, the level of serum idiotype and anti-idiotype antibodies, the size and volume of periovular granulomas formed in the liver, all that failed to show statistically significant differences between the two groups. After analysing all these data, other factors, that apparently have been hitherto negleted, rested to explain the findings. Among them, the timing and sequence of the egg-induced intrahepatic vascular changes seemed crucial. The sequential development of intrahepatic portal vein obstruction, followed by the opening of periportal collateral veins and the continous arrival of schistosome eggs going to be lodged into the latter, appeared as essential steps in the pathogenesis of "pipestem" fibrosis

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To determine the influence of physical factors on oviposition of Lutzomyia migonei (Diptera: Psychodidae) under laboratory conditions, two sets of experiments were performed. The first test was to determine the influence of the size of pots on oviposition. Gravid flies were placed individually or in groups in different oviposition pots. The number of eggs laid, oviposition time and survival of gravid females were observed. In the second experiment, the influence of irregular surfaces on oviposition was studied. The results suggested that physical space was not an important factor in the oviposition behavior of L. migonei and that the flies showed a preference to oviposit on irregular horizontal surfaces in response to thigmotropic behavior

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The following hypotheses were tested for groups of simultaneous hermaphrodites Biomphalaria tenagophila: (a) snails that have low reproductive success during the process of self-fertilization do not increase their reproductive success after the end of grouping; (b) the copulation behaviour and the presence of one snail whose eggs have a low viability rate influence the partner's reproductive success by cross-fertilization. Groups were constituted by a homozygous pigmented snail and two albinos: one with a viability rate higher than 70% ("good reproducers") and the other less than 10% ("bad reproducers"). All pigmented snails had viability rates higher than 70%. The "good" and "bad" reproducer albino snails had similar copulation behaviour. However, after the end of grouping, the "bad reproducers" continued to have viability rates less than 10% over 30 days. In 100% of the cases that pigmented snails copulated (performing either a male role or simultaneously male and female roles) exclusively with "good" reproducer albinos, they presented high reproductive success (producing, on average of 8.4 pigmented embryos/egg-mass). However, in 100% of the cases that pigmented snails copulated with both partners, the "good" reproducer albino snails produced none or very few embryos (the highest average was 2.2 pigmented embryos/egg-mass). Therefore, the production of viable embryos by cross-fertilization was more influenced by self-fertilization performance than by copulation behaviour. The presence of a snail whose eggs have a low viability rate could decrease their partners reproductive success

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Schistosomes, ancestors and recent species, have pervaded many hosts and several phylogenetic levels of immunity, causing an evolutionary pressure to eosinophil lineage expression and response. Schistosoma mansoni adult worms have capitalized on the apparent adversity of living within the mesenteric veins, using the dispersion of eggs and antigens to other tissues besides intestines to set a systemic activation of several haematopoietic lineages, specially eosinophils and monocytes/macrophages. This activation occurs in bone marrow, spleen, liver, lymph nodes, omental and mesenteric milky spots (activation of the old or primordial and recent or new lymphomyeloid tissue), increasing and making easy the migration of eosinophils, monocytes and other cells to the intestinal periovular granulomas. The exudative perigranulomatous stage of the periovular reaction, which present hystolitic characteristics, is then exploited by the parasites, to release the eggs into the intestinal lumen. The authors hypothesize here that eosinophils, which have a long phylogenic story, could participate in the parasite - host co-evolution, specially with S. mansoni, operating together with monocytes/ macrophages, upon parasite transmission.

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Worm burdens recovered from inbred mice strains, namely C57Bl/6, C57Bl/10, CBA, BALB/c, DBA/2 and C3H/He, conventionally maintained in two institutional animal houses in the State of Rio de Janeiro, RJ, Brazil, were analyzed and compared, regarding their prevalences and mean intensities.Three parasite species were observed: the nematodes Aspiculuris tetraptera, Syphacia obvelata and the cestode Vampirolepis nana. A modification of the anal swab technique is also proposed for the first time as an auxiliary tool for the detection of oxyurid eggs in mice

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Fimicolous Staphylinidae prey on rearing dipterous in cattle dung, acting as their natural controllers, including pests such as horn fly. To survey the abundance and succession of these coleopterans in cattle dung deposited in pasture, six experiments were conducted from March to October 1995 in Uberlândia, State of Minas Gerais, Brazil. Cattle dung pats were exposed at a pasture for 1 hr, 8 hr, 24 hr, 2, 3, 7 and 10 days and were than taken to laboratory separate from each other, for Staphylinidae extraction. A total of 156 dung pats were exposed at pasture, from which 6225 Staphylinidae were recovered. Representing at least 30 species. Staphylinidae sp.1 (29.6%), Philonthus flavolimbatus (22.2%), Heterothops sp.1 (16.6%), Oxytelus sp.2 (7.6%), Aleochara sp.2 (7.6%) and Criptobium sp.1 (4.4%) were the most abundant, representing 87.8% from the total. The increased frequency of the majority of these species along the dung exposition time at pasture, indicated tha, they would be preying on at all the immature stages of the dipterous, or eggs and first instar larvae of species that lay eggs on the dung after its second exposition day at the pasture