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A Bretaña

Publications and source records attributed to A Bretaña.

18 recordsLinked to original sources
PubMed2002

Multiple infection in bovines from the tropics: observation of blood parasites by scanning and transmission electron microscope.

Blood samples from a splenectomized bovine, experimentally inoculated with blood from a field cow living in southwestern Venezuela, were processed for transmission and scanning electron microscopy. The blood sample showed multiple infection with hemoparasites of the genera Anaplasma marginale, Eperythrozoon wenyonii and Trypanosoma vivax. Scanning electron microscope showed that the blood from bovines with multiple infection had profound deformation in knob-like protruding structures with reduced cellular volume similar to echinocyte red blood cells. E. wenyonii parasites appear associated with the membrane, grouped in shallow to severe invaginations at the surface of the erythrocytes. The morphology of the parasites is predominantly rod-like; they also appear as coccoid-shaped and bifurcate or triskelion-shaped organisms. The organisms are present in pairs or clusters. T. vivax appeared with double flagella, which indicates active cellular division and infection processes. Transmission electron microscope study showed erythrocytes infected with intracytoplasmic bodies of A. marginale and with E. wenyonii embedded in the external membrane cell, with mature, juvenile and dividing forms present.

Anaplasma↗
PubMed2000

Disruption of the intestinal barrier and bacterial translocation in an experimental model of intestinal obstruction.

Clinical evidence and the use of experimental models in laboratory animals indicate that the intestine is a reservoir of microorganisms that can cause systemic infection in the human. The purpose of this work was to study the possible effect of intestinal obstruction (IO) on the mechanical and chemical barriers that bring protection against microorganisms crossing from the intestinal lumen towards the systemic tissues. We demonstrated that 24 hours after IO, histological and ultrastructural alterations do occur, seriously compromising the structure of the intestinal barrier in 100% of the studied animals. Likewise, it was observed that during the same period, microorganisms translocation from intestine to the peritoneal cavity and liver (100 and 80% respectively) occurred. The lungs were spared. Changes observed in the intestinal epithelium are related to a process similar to that produced by intestinal ischemia: mitochondrial destruction, with subsequent decrease of its capacity to supply energy and to preserve the equilibrium and structure of the intestinal epithelium. We propose that translocation of enteric bacteria may be the cause of the infection that brings about the death a significant group of animals at 48 hours (27%) and 72 hours (33%) post-IO.

Animals↗
PubMed1999

[Ultrastructural identification of Ehrlichia sp in an experimentally infected dog in Venezuela].

This study is the first report made in Venezuela concerning the ultrastructural characteristics of Ehrlichia sp in mononuclear blood cells from an experimentally infected dog. The animal developed clinical manifestations characteristic of the infection, and typical intracitoplasmic inclusion bodies were clearly seen in blood smears stained with modified Giemsa examined by light microscopy. Microorganisms were visualized by transmission electron microscopy. The cytoplasmic inclusions, consisted of membrane-lined vacuole-containing elementary bodies. The organisms were extremely pleomorphic. Elementary bodies were surrounded by two distinct membranes and each was constituted by electro-dense granules. These findings corresponded to the described electron microscopy morphology which characterizes the Ehrlichia genus.

Animals↗
PubMed1995

Comparative ultrastructure and immunolabeling of MHC-II antigens of alveolar macrophages obtained from patients with paracoccidioidomycosis and other lung diseases.

Samples of alveolar macrophages (AM) obtained by bronchoalveolar lavage from patients with either paracoccidioidomycosis, silicosis, sarcoidosis, or allergic alveolitis were investigated by electron microscopy and immunocytochemistry to compare cellular ultrastructure and expression of MHC-II antigens in the AM cell surface. All samples of AM obtained from patients with these pathologies showed heterogeneous structural features. Although, this morphological diversity is also present in AM of healthy donors, our observations seem to indicate that in the diseases studied this morphofunctional diversity is associated with additional ultrastructural characteristics inherent to each disease. In paracoccidioidomycosis the proportion of vacuolated macrophages is significantly lower than in other diseases; this might indicate that in paracoccidioidomycosis the proportion of activated AM is smaller. We observed significant differences in the expression of MHC-II antigens. Silicosis, sarcoidosis, and allergic alveolitis do not differ significantly in the quantity of immunolabeled AM or in the distribution of the label. The percentage of AM from paracoccidioidomycosis that exhibit the MHC-II molecule is very low with poor immunolabeling. In this disease the low expression of the MHC-II molecule could be related to a decrease of the antigen presenting function by AM.

Alveolitis, Extrinsic Allergic↗
PubMed1993

Antigen recognition on Anaplasma marginale and bovine erythrocytes: an electron microscopy study.

The reactivity of sera from Anaplasma marginale-infected bovine with red blood cells and with purified anaplasma bodies was analyzed by electron immunomicroscopy. Red blood cells from non-infected and from anaplasma-infected cows and A. marginale bodies separated from parasitized erythrocytes, were incubated with control, pre-immune and immune sera followed by anti-bovine IgG-Peroxidase. Immune sera from cows infected with the venezuelan and Florida isolate reacted with red blood cell membranes from normal and infected bovines, while sera from non-infected cows did not. The immune sera also recognized epitopes localized on the cell wall, membrane and on unidentified intracellular structures of the purified anaplasma bodies. Thus, we propose that A. marginale infection may cause structural and biochemical modifications of the plasma membrane of the bovine red blood cells during its intraerythrocytic cycle. This in turn could elicit an autoimmune type of response against its own cells that would stimulate erythrophagocitosis. The strong reactivity of the immune sera with the Anaplasma bodies suggests that the bovine immune system also recognizes epitopes located on the parasite.

Anaplasma↗
PubMed1992

American Leishmania spp. and Trypanosoma cruzi: galactosyl alpha(1-3) galactose epitope localization by colloidal gold immunocytochemistry and lectin cytochemistry.

Patients with Chagas' disease or different clinical forms of leishmaniasis (cutaneous or visceral) have elevated galactosyl alpha (1-3)galactose antibodies. Using colloidal gold immunocytochemistry--monoclonal antibody gal-13 (specific for lipid-linked galactosyl alpha (1-3)galactose residues) and anti-nidogen antibodies and lectin cytochemistry (Bandeiraea simplicifolia IB4), both techniques specific for demonstrating galactosyl alpha (1-3)galactose residues--we have found terminal disaccharide residues on the Trypanosoma cruzi external surface of Vero cell-derived trypomastigotes but not in intact epimastigotes (although disrupted epimastigotes strongly stained), in the lips of the flagellar pocket, and on the parasitic side exactly opposite to the flagellar pocket in amastigote and promastigote forms of American Leishmania. These results resemble those obtained using anti-laminin antibodies in both trypanosomatids. In addition, results obtained with anti-nidogen antibodies seem to recognize in Trypanosoma cruzi and American Leishmania culture forms another different unknown terminal disaccharide. These results confirm the presence of terminal galactosyl alpha (1-3)galactose residues in both trypanosomatids, and that rabbit anti-laminin antibodies are indeed also recognizing galactosyl alpha (1-3)galactose residues as demonstrated for human circulating antibody. The presence of abundant galactosyl alpha (1-3)galactose residues on Trypanosomatid family members suggests a specific unknown role in parasite physiology for this terminal disaccharide.

Animals↗
PubMed1989

Digestion of killed Paracoccidioides brasiliensis by neutrophils.

We previously described an in vitro assay showing that neutrophils (PMNs) from patients with paracoccidioidomycosis (PARA) have a specific digestive deficiency against suspensions of live Paracoccidioides brasiliensis. We now report that this defect is equally detectable against autoclaved, but not Amphotericin B-killed P. brasiliensis. The use of autoclaved suspensions facilitates the use of our in vitro assay. It might allow the development of an in vitro intradermal test for digestion of fungi. Differential digestive ability of phagocytes against live (or autoclaved) and Amphotericin-B killed fungi is of conceptual interest. It may be relevant in understanding therapeutic effect of Amphotericin B.

Amphotericin B↗
PubMed1986

Trypanosoma cruzi and American Leishmania spp: immunocytochemical localization of a laminin-like protein in the plasma membrane.

Patients with Chagas' disease or different clinical forms of American cutaneous leishmaniasis have high antilaminin antibody levels. An immunogold technique employing a specific antilaminin antibody was used in the present study to determine the presence, and define the ultrastructural localization, of laminin-like molecule(s) in American Leishmania spp. and Trypanosoma cruzi. Laminin was found located specifically in T. cruzi trypomastigotes on the external surface of the plasma membrane, close to the sites where the flagellar veil attaches to the plasma membrane. Laminin immunoreactivity was rapidly lost when trypomastigotes were cultured in liquid medium and no reactivity was found in fresh epimastigotes. Promastigotes and amastigotes of American Leishmania spp. also showed a specific localization of laminin immunoreactivity, this being limited to the lips of the flagellar pocket and to the parasitic side exactly opposite to the flagellar exit. These results confirm the presence of a laminin-like molecule(s) in both trypanosomatids, the specific localization suggesting a presently unknown function for this protein.

Animals↗
PubMed1985

Chédiak-Higashi syndrome in a Venezuelan black child.

One case of Chédiak-Higashi syndrome (CHS) in a black male child, born to a consanguineous couple from a rural village in the State of Falcón, is described. At birth the child had marked skin depigmentation and ash-gray hair. A few months later he developed an almost normal black skin color. The diagnosis of CHS was established by the presence of large peroxidase-positive granules in his leukocytes. Neutrophils showed decreased chemotaxis and lack of digestive capacity against Candida albicans. Unusual features included extreme rarity of CHS in blacks, progressive repigmentation of the skin, and an early benign evolution. A high consanguinity index in the village from which this patient originated raised the possibility of the presence of a new cluster of this disease in Venezuela.

Black or African American↗
PubMed1983

Leishmania species: comparative ultrastructure of experimental nodules and diffuse human cutaneous lesions in American leishmaniases.

Experimental nodules of American leishmaniases were obtained by inoculating 0.1-1 x 10(5) amastigotes into the dorsum of the hindpaws of golden hamsters and of C57Bl/6J mice. The amastigotes were obtained by biopsy of lesions in six human cases of cutaneous leishmaniases and were serially maintained in golden hamsters and in a fetal calf serum-containing medium. Human nodules were obtained by biopsy from several patients with diffuse cutaneous leishmaniases, always prior to treatment. Within the same host species, no ultrastructural differences were seen in the tissue response to isolates of Leishmania mexicana, L. brasiliensis, or L. garnhami, nor were there differences between the host species in response to a particular isolate of the genus Leishmania. The typical inflammatory response was a macrophage granuloma with abundant polymorphonuclear neutrophils, some eosinophils, and plasma cells. Simple human cutaneous leishmanial lesions, as well as experimental nodules in regression, show many fibroblasts, much collagen fiber, but very few parasites. In typical lesions, parasites occurred within macrophage phagolysosomes, within distended lacunar cells, and in the intercellular spaces. Leishmaniae strongly adhered to parasitophorous vacuoles by a site of their plasma membrane directly opposite the flagellum, and the host cell cytoplasm close to the adherence site became highly vacuolated. In most cases the intra- and extracellular parasites show normal morphology, which suggest the inability of phagocytic cells to attack them.

Adolescent↗
PubMed1983

A minimal medium for the cultivation of infective Trypanosoma cruzi epimastigotes.

In a culture medium containing bovine liver catalase, but lacking exogenous free amino acids, only two vitamins (choline and folic acid) were found to be essential for the continuous in vitro multiplication of seven different infective strains of Trypanosoma cruzi. The provision of additional vitamins or sugars had no stimulatory effect under these culture conditions. These, and previous studies, have allowed the design of a trypanosomal minimal medium composed only of bovine liver catalase, choline, folic acid, glucose and inorganic salts. This was able to support the continuous cultivation of T. cruzi for more than 12 consecutive passages (i.e. about 160 d of culture). By several criteria, namely morphological features as seen by electron microscopy, infectivity for vertebrate and invertebrate hosts, glucose utilization and protein biosynthesis, this medium (which is the simplest so far described) proved to be nutritionally adequate for Trypanosoma spp. In addition, the medium appeared to be relatively specific for T. cruzi, as it did not support the growth of T. rangeli and American isolates of leishmania.

Animals↗
PubMed1983

Ultrastructural aspects of intraerythrocytic development of a Venezuelan strain of Anaplasma marginale.

Blood samples from splenectomized calves infected with a Venezuelan strain of Anaplasma marginale were studied by electron microscope. A. marginale appears to invade erythrocytes by the invagination of the host cell plasma membrane. The parasite reproduces by binary or multiple fission, changing from a rounded to an irregularly polyhedral form during and after division. The mature Anaplasma, within the host red cell modifies the erythrocytes cytoplasma and external membrane producing pores through which the parasite can escape without lysing the host erythrocyte.

Anaplasmataceae↗
PubMed1979

Acid and neutral hydrolases in Trypanosoma cruzi. Characterization and assay.

Twelve acid hydrolases, 4 near-neutral hydrolases, and alkaline phosphatase were demonstrated in 0.34 M sucrose homogenates of Trypanosoma cruzi strain Y: p-nitrophenylphosphatase and alpha-naphthylphosphatase, with optimum pH at approximately 6.0; alpha=ga;actpsodase. beta=ga;actpsodase. beta=g;icpsodase, N-acetyl-beta-glucosaminidase, cathepsin A and peptidase I and III, with optimum pH between 5.0 and 6.0; and arylsulfatase, cathepsin D, alpha-arabinase and alpha-mannosidase with optimum pH at approximately 4.0. alpha-Glucosidase, glucose-6-phosphatase and peptidase II had optimum pH at approximately 7.0. beta-Glycerophosphatase had a broad pH-activity curve from 4,0 to 7.4, with maximum activity at pH 7.0. The main kinetic characteristics of these enzymes and their quantitative assay methods were studied. No activity was detected for alpha-fucosidase, beta-xylosidase, beta-glucuronidase, elaidate esterase, acid lipase, and alkaline phosphodiesterase.

Animals↗
PubMed1979

Chemotherapy with ethidium bromide-DNA complex in established Chagas' disease.

Two different strains of mice (AKR and NMRI-IVIC) were inoculated intraperitoneally with the virulent Y strain of Trypanosoma cruzi, and then treated with the lysosomotropic ethidium bromide-DNA complex, according to several different treatment schedules. When animals were treated 48 hours after intraperitoneal inoculation with three intraperitoneal doses of EB-DNA no parasitemia was detected, even after 11 weeks, confirming previous results. However, when infection was allowed to become fully established, that is 3-4 weeks after inoculation, and then challenged with several different treatment schedules (with varied doses and timing of administration) we failed to cure established Chagas' disease, suggesting that the claim of effectiveness for this EB-DNA complex is limited to early Chagas' disease.

Animals↗