Abstract in English:The eggs from oviparous organisms contain large amounts of vitellus, or yolk, wich are utilized by the growing embryo. Vitellogenesis is the process of vitellus accumulation and involves massive heterosynthetic synthesis of the protein vitellogenin (Vg) and its deposition in the oocyte. This work summarizes data on Vg structure, synthesis, uptake by oocytes and its fate during embryogenesis. The hormonal control of vitellogenesis and its tissue, sex and temporal regulation are also discussed. Where it is available, data on structure and expression of Vg-coding genes are reviewed. Insect vitellogenesis is priorized although other oviparous animal groups outside insects are also treated.
Abstract in English:Flight activity and invasion of houses by Triatoma sordida and T. guasayana were studied in the Province of Santiago del Estero, Argentina. Spontaneous findings of both species in houses were recorded from 1982 to 1989. Light trap collections were performed in 1982, 1983 and 1984, at the woods surrounding the settlements of Amamá (43 houses) and Trinidad (19 houses). Most of the 101 triatomines collected, were unfed and negative for Trypanosoma cruzi. T. guasayana predominated over T. sordida, and both appeared on the lighted screens between 19-31 min (mean 24) after dusk and the catch time was 30-45 min. Although entomological evaluation of 41 houses at Amamá performed in September 1985, just before insecticidal spraying, showed that Triatoma infestans predominated, adults of T. guasayana were collected in sleeping places, in 7 houses (17%). Most triatomines invading houses from then up to 1990 were flying T. guasayana (20/27) and females outnumbered males. Three non infected T. guasayana females were fed on man and two T. guasayana males positive for "T. cruzi like" trypanosomes were unfed. Therefore, visiting hungry adults could transmit T. cruzi to people and introduce wild parasites to the domestic cycle. T. guasayana stands as the main potential substitute of T. infestans in the studied area, and it might play there the same role as T. sordida in Brazil.
Abstract in English:Two new Brazilian species of Downeshelea Wirth & Gorgan D. fluminensis and D. quasidentica, are described and illustrated.
Abstract in English:Four cytotypes of Simulium exiguum occur in Ecuador, where this morphospecies is the primary vector of onchocerciasis. In this paper, we give the first full description of the banding pattern of the larval polytene chromosomes of the Quevedo cytotypes differ from the chromosomal standard sequence (of the Cayapa cytotype) by the fixed inversions IIL-5 and IIL-6. The Quevedo cytotype additionally differs from the standard and Bucay cytotypes by processing a differentiated X chromosome, wich is indicated by the inversion IIS-A. As the degree of reproductive isolation between the Bucay and Quevedo cytotypes has not yet been estabilished, they must be regarded as intraspecific variants of the same species. In fact, isoenzyme characterizations showed that the Bucay and Quevedo cytotypes are differentiated only to the extent expected of incipient species or geographical populations. Moreover, the sibiling species status previously given to the Bucay cytotype needs be reassessed, there being inadequate analysis from areas in Ecuador where Bucay occurs in sympatry with the standard Cayapa cytotype. No isoenzyme electromorphs were discovered that identified all or mostadult females of any one (cytotype-pure) collection.
Abstract in English:Postembryonic development of Misumenops pallida (Keyserling) (Araneae, Thomisidae), one of the most abundant predator species in soybean fields in Buenos Aires Province (Argentina) was studied. The life cycle was observed in the laboratory from egg sacs collected in the field, and from egg sacs spined in the laboratory by gravid females collected in the field. Results indicated that instar length and feeding rate increased throughout the life cycle being higher in females than in males. Greater mortality was observed to third and fourth instars decreasing thereafter. These results may contribute to deternmine the efficiency of this species as a natural enemy of insect pests of soybean.
Abstract in English:Fecal egg count scores were used to investigate the distribution and abundance of intestinal helminths in the population of a rural village. Prevalences of the major helminths were 41% with Ascaris lumbricoides 60% with Trichuris trichiura and 50% with Necator americanus. All three parasites showed a highly aggregated distribution among hosts. Age/prevalence and age/intensity profiles were typical for both A. lumbricoides and T. trichiura with the highest worm burdens in the 50-10 year old children. For hookworm both prevalence and intensity curves were convex in shape with maximum infection levels in the 30-40 year old age class. Infected females had higher burdens of T. trichiura than infected males in all age classes of the population; there were no other effects of host gender. Analysis of associations between parasites within hosts revealed strong correlations between A. lumbricoides and T. lumbricoides and T. trichiura. Individuals with heavy infections of A. lumbricoides and T. trichiura showed highly significant aggregation within households. Associations between a variety of household features and heavy infections with A. lumbricoides and T. trichiura are described.
Abstract in English:This paper deals with the morphology of Pomacea caniculata (Lamarck, 1822) collected at Corrientes, Argentina. Comparison is made with Pomacea lineata (Spix, 1827) and Pomacea sordida (Swainson, 1823). The shell is globose, heavy, with greenish or horn-colored periostracum and dark spiral bands; apex subelevated, 5-6 whorls increasing rather rapidly and separated by very deep suture. Aperture large, rounded to subelongated; lip sometimes reddish; umbilicus large and deep; operculum corneous, entirely closing the aperture. Ratios: shell width/shell length = 0.78-0.96 (mean 0.86); aperture length/shell length = 0.68-0.77 (mean 0.72). Radula similar to other congeneric species. Testis and spermiduct as in P. lineata and P. sordida; prostate cylindric and short, cream in color as the testis. Penial sheath straight bearing a central outer gland deeply embedded in the tissue of its basal portion and a large wrinkled gland occupying 2/3 of the distal tip of its inner surface; the rigth margin of the sheath overlaps the left one until 2/3 of its proximal end. Female reproductive apparatus similar to that P. lineata; vestigial male copulatory apparatus (penis and its sheath) present in all females examined.
Abstract in English:The blood cells of the pulmonate snail Biomphalaria tenagophila, an important transmiter of the trematode Schistosoma mansoni in Brazil, were examined by ligth and transmission electron microscopy (TEM). Two hemocyte types were identified: hyalinocytes and granulocytes. Hyalinocytes are small young (immature), poorly spreading cells, which have a high nucleocytoplasmic ratio and are especially rich in free ribosomes. They do not appear to contain lysosome-like bodies and represent less than 10% of the circulating hemocytes. Granulocytes are larger hemocytes which readily spread on glass surface and which strongly react to the Gomori substrate, indicating the enzyme acid phosphatase usually found in lysosomes. Ultra-structurally, they contain a well-developed rough endoplasmic reticulum, dictyosomes and some some lysosome-like dense bodies. Granulocytes do not exhibit a characteristic granular aspect and the few granules observed in the cytoplasm should correspond to a lysosome system. They were named granulocytes instead of amoebocytes to use the same terminology adopted for Biomphalaria glabrata in order to make easier comparative studies. This is a preface study for more specific investigations on the functional activities of the blood cells of B. tenagophila and their interactions with the trematode parasite.
Abstract in English:Raillietina (Raillietina) guaricanae n. sp. is described from the wild rats Oryzomys intermedius, O. nigripes and O. ratticeps, captured in the Environmental Protection Area of Guaricana, from November 1988 to December 1989. Raillietina (Railietina) guaricanae n. sp. is closely related to the Neotropical mammalian Raillietina, however it differs by the fewer number of rostellar hooks, and tests different number of eggs capsules and host species. The number of known species of Raillietina (Raillietina), parasites of mammals in the Neotropical Region, is increased to four.
Abstract in English:The susceptibility of four isolates of Schistosoma mansoni (BH, MAP, MPR-1 and K) to four multiple doses of anti-schistosomal agents (hycanthone, niridazole, oxamniquire, and praziquantel) were evaluated in infected female Swiss albino mice. These schistosomal isolates had been maintained in the laboratory without further drug pressure for 20 to 30 generations. Multiple dosage regimens were used for each drug against each isolate of S. mansoni to generate ED50 (effective dose 50%) values. Results demonstrated that the K isolate is resistant to niridazole, the MPR-1 isolate to oxamniquine, and the MAP isolate to both hycanthone and oxamniquine. The BH isolate was susceptible to all drugs and was used as the reference isolate. All isolates were susceptible to praziquantel. The significance of the difference in response of the MPR-1 and MAP isolates is discussed. These results confirm the resistance of these isolates of S. mansoni of three schistosomicides and demonstrate that the resistance of these isolates are stable over long periods of time without exposure to drugs.
Abstract in English:A kinetic study of the cells present in the spleen of BALB/c mice infected with Schistosoma mansoni was carried out. The lymphocytes were evaluated phenotypically with monoclonal antibodies and the effect of splenectomy on the modulation of periovular granuloma was also investigated. The infected mice had proportional increases in the numbers of neutophils, plasma cells, macrophages and eosinophils in the spleen. The largest number of neutrophil, plasma cells and macrophage were found between the 8th and the 12th week of infection, while the amount of eosinophils were higher later on, around the 20th week. The lymphocytes phenotipically characterized as Thy 1.2, Lyt 1.2 (CD4) increased mildly in proportional numbers. However, the percentage of lymphocytes with the Lyt 2.2 (CD8) phenotype, which is characteristic of supressor and cytotoxic T cells, increased significantly with the progress of the disease. The numbers of B lymphocytes, which comprise 50% of the mononuclear cells present in the spleen, increased significantly till the 16th week they began to decrease. The mean diameters of periovular granulomas were comparatively similar in both experimental groups (splenectomized and non-splenectomized mice). However, the evolutive types of granuloma (exudative, intermediate and fibrous) in splenectomized mice were proprtionally different from those of non splenectomized mice in the 16th and 24th week of infection. It is inferred that lymphonodes or other secondary lymphoide organs, in the abscence of the spleen, assume a modulating action on periovular granulomas, although the evolution of the granulomas is somehow delayed in splenectomized mice.
Abstract in English:In order to characterize the epidemiology of American Cutaneous Leishmaniasis (ACL) in a periurban area of the municipality of Sabará in the metropolitan region of Belo Horizonte (MRBH), an area until then considered free of the disease, a cross sectional survey was undertaken in 1990. The survey of the population consisted of 1119 interviews and 881 clinical examinations using Montenegro's skin test (MST). A low prevalence (3.7%) of positive MST was encountered. The disease had been occuring in the area for about 20 years in the form of sporadic cases. The predominant species of sandfly both in domestic areas and nearby areas of secondary vegetation was Lutzomyia whitmani. A canine survey of delayed hypersensitivity to the antigen P10,000 identified only one dog with a positive reaction out of 113 examined. The transmission of ACL in MRBH was confirmed. The occurrence of the disease in women, children and individuals with no contact with forest areas as well as the presence of potential vector species in the domiciliar environment, suggests the transmission of the disease in this environment.
Abstract in English:Non-viable cells and biochemical fractions from Paracoccidioides brasiliens were obtained for experimental inoculation in mice and posterior histopatological analysis. Dead total fungus, total fungus disrupted by sonorous waves, lipids of the fungus, supernatant of the lipid purification, integral and disrupted fungus free of lipids were obtained. The six preparations arised from masses of lyophilized yeasts of a recent isolate of P. brasiliensis (strain JT-1) and from a "Pool" equitably constituted by four strains maintained in laboratory for a long time (SN, 2, 18 and 192). Different doses of the 12 preparations were intraperitonially inoculated and histopathological analysis were done 30 days later. This analysis showed that all the inoculated preparations gave origin to inflamatory foci, except the one designated "supernatant of lipid purification". The alterations were detected exclusively in the liver of the animals and occurred from the smallest dose tested (1 mg), with exception of the lipids of the fungus, where the foci appeared only from a 3 mg dose onwards. No difference in the capacity of inducing histopathological alterations was found between the preparations obtained from the recent isolate (JT-1) and from the older ones ("Pool"). On the other hand, an increase of the number of inflammatory foci in function of the inoculated dose was observed.
Abstract in English:A dot enzyme linked immunosorbent assay (dot-ELISA) was previously developed to detect specific antibodies in rabbits sera immunized against FIA protein obtained from Yersina pestis. This antigen was covalently linked onto the surface of dacron (polyethyleneterephthalate). Here, standard conditions are described for the optimization of this procedure: an amount of 20 ng of FIA protein was fixed onto dacron; anti-rabbit IgG peroxidase conjugate diluted 1:8,000 and 30% non-fat instant milk as blocking substance were used throughout the method. This procedure was compared with that employing nitrocellulose as solid-phase which showed to be more sensitive. However, the method based on dacron did not show false positive reactions against non-immunized rabbits sera at low antigen amount and diluted anti-IgG peroxidase conjugate.
Abstract in English:Pulmonary infection on cystic fibrosis (CF) patients are associated with a limited qualitative number of microorganisms. During the colonization process, Staphylococcus aureus usually preceedes Pseudomonas aeruginosa. This latter is at first non-mucoid, being replaced or associated to a mucoid morphotype which is rare in other diseases. In 1980, Pseudomonas cepacia appeared as an important agent in CF pulmonary infections with a mean frequency of about 6.1% isolations in different parts of the world. The primus colonization mainly occurs in the presence of pre-existent tissue lesions and the clinical progress of the disease is variable. In some patients it can be fulminant; in others it can cause a gradual and slow decrease in their pulmonary functions. The concern with this germ isolation is justified by its antibiotic multiple resistence and the possibility of direct transmission from a colonized patient to a non-colonized one. We reported the first case of P. cepacia infection in a CF patient in our area. The microbiological attendance to this patient had been made from 1986 to 1991 and the first positive culture appeared in 1988. The sensitivity profile showed that the primus colonization strain was sensitive to 9 of 17 tested antibiotics, however in the last culture the strain was resistent to all antibiotics. These data corroborate the need for monitoring the bacterial flora on CF patients respiratory system.
Abstract in English:Extracellular proteins produced by Bacillus cereus AL-42 and AL-15 were fractioned by chromatography on QAE-Sephadex and Sephadex G75. This last chromatographic process resulted in three peaks. The major peak showed vascular permeability activity to rabbits, lethality to mice, and cytotoxicity to Vero and Hela cells. The analysis by SDS-PAGE after ultrafiltration confirm recent findings that the enterotoxin is a compound with molecular mass > 30.000.
Abstract in English:Nosocomial infections are a relevant factor in complicating the recovery of patients interned for even minor causes. In attempt to determine their origin it is crucial to consider that their origin is of an endogenous nature. Looking for an acessible expression of intestinal colonization we analyzed fecal samples from 3 separate groups of hospital patients collected after different lenghts of time. For practical reasons one group was studied prospectively and two other groups (patients hospitalized for up to 7 days and patients hospitalized for more than 7 days) were compared to one another. We looked for the emergence of tellurite resistance among Enterobacteriaceae using a selective medium. MacConkey potassium tellurite (MCPT). The frequence of prospectively studied patients with tellurite resistant strains was significantly greater after 7 days of hospitalization. For the two other groups, patients with more than 7 days of hospitalization showed a significant increase of bacterial species and of strains with new antimicrobial resistance markers. High molecular weigth plasmids were detected in some of these strains. These data show that the MCPT medium is a useful tool for the investigation of bowel colonization in hospitalized patients by drug-resistant Enterobacteriaceae.
Abstract in English:Pulmonary lesions compatible with adenovirus infection were detected by gross and microscopic examination of autopsy tissues children aged from 5 to 34 months. Hepatic lesions indicative of systemic infection were also found in four of the chisldren. The viral etiology was confirmed in three cases by in-situ hibridization, electro-microscopy and immunofluorescence performed in parafin-embedded tissues, and in one case by cell culture isolation of adenovirus type 2 from nasopharyngeal exudate. Routine testing by methods additional to conventional light microscopy would probably have revealed a larger number of adenovirus infections among the 1.103 autopsy records analyzed in this study.
Abstract in English:Ketoconazole an azole antifungic drug which is already in the market has also been demonstrated to be active against Trypanossoma cruzi experimental infections. In this paper we confirmed the drug effect and investigated its range of activity against different T. cruzi strains naturally resistant or susceptible to both standard drugs Nifurtimox and Benznidazole used clinically in Chagas disease. Moreover, we have shown that the association of Ketoconazole plus Lovastatin (an inhibitor of sterol synthesis), which has an antiproliferative effect against T. cruzi in vitro, failed to enhance the supressive effect of Ketoconazole displayed when administered alone to infected mice. Finally, administration in chronic chagasic patients of Ketoconazole at doses used in the treatment of deep mycosis also failed to induce cure as demonstrated by parasitological and serological tests. The strategy of identify and test drugs which are already in the market and fortuitously are active against T. cruzi has been discussed.
Abstract in English:Due to the narrow therapeutic range of theophyline, plasma concentrations of this drug are monitored in patients undergoing chronic therapy. Slow-release preparations avoid the fluctuations in plasma levels and improve patient compliance. In this study, we have compared the pharmacokinetic profiles of a theophylline slow-release tablet and a syrup form, when administered in multiple doses to healthy adult volunteers. The classification based upon releasing patterns is confirmed.