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M H Burgos

Publications and source records attributed to M H Burgos.

At least 19 recordsLinked to original sources
PubMed2006

A novel icetexane diterpene, 5-epi-icetexone from Salvia gilliessi is active against Trypanosoma cruzi.

In this work the effect of a novel compound, 5-epi-icetexone (ICTX) obtained from Salvia gilliessi Benth. (Labiatae), is studied on cultured epimastigotes of Trypanosoma cruzi (Tulahuen). It was found that the compound exerts an antiproliferative effect on the parasites at concentrations between 2.8 and 4.2 microM, and similar sensitivity in other strains (Dm28c, CL-Brener and Y-strain). The compound was deleterious at concentrations higher than 4.2 microM, with an estimated IC50 of 6.5+/-0.75 microM, but with low cytotoxicity to mammalian cells. These effects were irreversible, even at short times of exposure to the drug. In solution, ICTX showed to be stable for at least 96 h at 29 degrees C. With cytostatic dose a little percentage of parasites was resistant to the action of ICTX, and they continued growing although with different kinetic. By electron transmission microscopy, at dose of 4.2 microM an external vesiculization was observed on the first day of exposure to the compound, but the parasite cytoplasm became plenty of vacuoles and exhibited nuclear disorganization from the second day of exposure. It was concluded that ICTX is active against T. cruzi and may act by multiple mechanisms. In future, this novel icetexane diterpene may be a good candidate for therapeutic use against Chagas' disease.

Animals↗
PubMed2000

Xenopus laevis embryo development: arrest of epidermal cell differentiation by the chelating agent 1,10-phenanthroline.

The embryonic epidermis of stage 35 Xenopus laevis embryos is a highly differentiated structure composed of four cell types arranged in a regular architecture. Each type is distinguished by its distinct morphological characteristics. Some cells are ciliated (type 1); others have their surfaces covered by abundant, secreted vesicles of 0.1 microm diameter (type 2), or multiple linear aggregates of spherical subunits on their apical surfaces (type 3) or large secreted vesicles that emanate from prominent apical holes of 1 microm diameter (type 4). In contrast, the macroscopic appearance of embryos exposed to 10 microM 1,10-phenanthroline (OP) as well as the ultramicroscopic structure and organization of their epidermal cells are markedly altered. The most predominant cells of the embryonic epidermis are undifferentiated and of heterogeneous size. They lack any characteristic morphology and are arranged irregularly. Ghost cells are also identified. The recognizable differentiated cells are decreased in number and present in a scattered arrangement. These are identified as either type 1 or 2 cells but with ciliae that are shorter and thicker than control or with only a few vesicles larger than 0.1 microm in diameter on their surface. No cells with linear aggregates or prominent apical holes are identified. Except for the altered epidermis, the embryos do not develop any other major organs and exhibit axial abnormalities with an average dorso-anterior index of three. Thus, the chelating agent OP perturbs metal dependent processes essential for terminal differentiation that may likely account for the resultant abnormalities of embryo organogenesis and morphogenesis.

Animals↗
PubMed1999

Immunocytochemical reaction of sera from chagasic patients against Trypanosoma cruzi, intestine of Triatoma infestans and normal human heart.

Chagas disease has been considered by some authors as an autoimmune pathology and denied by others. In this paper we present by means of immunocytochemical reactions with sera of chagasic patients, evidence in favor of the presence of similar antigens in the parasite, vector and non chagasic human heart. The immunocytochemical technique used permits the localization by electron microscopy of the antigens in the peritrophic membrane of the parasite and basement membranes of the vector's midgut and of the myosin band of the normal human heart. These observations support the assumption of an autoimmune response in Chagas disease.

Animals↗
PubMed1999

Morphometrical comparison of human spermatozoa obtained from semen and swim-up methodology.

Because morphology is regularly established in semen smears, but not in swim-up spermatozoa, we were interested in comparing some morphological parameters of semen and swim-up spermatozoa to establish if the cells selected by the swim-up method were morphologically similar to those considered normal in semen. Normal human semen samples were divided into two aliquots. One of these aliquots was washed by centrifugation with B2 medium and sperm smears were prepared with the resulting pellet as a control. The other aliquot was used to perform swim-up separation and the spermatozoa from the supernatant were used as experimental smears. Both groups were stained according to the triple stain technique and spontaneous acrosome reaction and viability were determined. Video microscopy and computer-assisted image processing of live and non-reacted sperm cells were used to establish morphometrical parameters of the sperm head in both populations. The following set of morphometrical parameters were considered: width, length, width/length ratio, acrosome area, head area, and acrosome area/head area ratio. An increase in head width, a decrease in head length and a subsequent increase of width/length ratio were found in swim-up cells compared with the control group. A slight increase in acrosome area/head area ratio was also observed in swim-up supermatozoa. Through the swim-up methodology we were able to select a subpopulation of oval shaped heads with spermatozoa having a bigger acrosome area in comparison to semen.

Acrosome↗
PubMed1998

Evolutionary sperm morphology and morphometry in armadillos.

Little is known about the evolution of vertebrate spermatozoa. In most eutherian taxa a high degree of uniformity in sperm shapes and dimensions among species was observed. The aim of this work is to trace a possible evolutionary change in sperm morphology and morphometry in dasypodids. The main difference between the spermatozoa of the studied armadillos is the shape of the sperm heads. We have classified the spermatozoa into 4 different groups according with their head shapes. Sperm from group 1 (Dasypus) are considered ancestral and are clearly separated from the others. The remaining sperm types are derivative ones; those from group 2 (Tolypeutes) are farther from those of groups 3 (Priodontes and Cabassous) and 4 (Chaetopractus, Zaedyus and Euphractus) which would have recently differentiated from each other. The sperm shape and size are not constant across taxa in armadillos; an important evolutive differentiation was established on the sperm morphology and morphometry between the different genera in Dasypodidae.

Animals↗
PubMed1996

Activation of macrophage functions by growth factor present in uterus and embryo extract of pregnant mouse.

A pregnant mouse uterus and embryo extract (PMUE) that contains growth hematopoietic factor (M-CSF or CSF-1), was used to test its action on the phagocytic and digestive functions of macrophage. Macrophages incubated with and without PMUE for 24 hours previous to each experiment were compared. A good phagocytosis of Trypanosoma cruzi by macrophages incubated with PMUE, was observed on video microscopy. No phagocytic activity was observed in the macrophages deprived of PMUE 24 hours before. The studies of phagocytic and degradative behavior of macrophages by both soluble and particulated (S. aureus) complex 125I-antibodies showed that total binding of soluble ligands was almost double in the group of macrophages incubated with PMUE. Both the soluble and particulated ligands were digested more efficiently by the macrophages stimulated by PMUE. Counting the macrophages with trypan blue, an equal viability was found, of the cells incubated with and without PMUE. From the experimental data obtained, we may conclude that the hematopoietic growth factor present in PMUE is essential for phagocytic and degradative functions of macrophages.

Animals↗
PubMed1994

Epididymal glycoprotein involved in rat sperm association.

Recently, a new head-to-head sperm association was described in the rat during epididymal transit. This association was called a rosette and a filamentous and PAS-positive material was also described joining the sperm heads. The beginning of rosette formation in the epididymis and the linking material between heads have remained unclear. Epididymides of adult rats were fixed by vascular perfusion and thin sections of the principal regions were studied by transmission electron microscopy (TEM). The first evidence of rosette formation was observed in the distal corpus. Rosettes were isolated from the distal corpus and processed for immunogold and immunofluorescence microscopy to detect an epididymal glycoprotein called DE. This glycoprotein is secreted by the corpus epididymis and appears to be involved in sperm maturation. Colloidal gold marks and fluorescence were observed in the linking material between the sperm heads. The results presented here show that rosettes begin to appear following the sites of DE secretion and permit us to postulate that DE is involved in rosette formation and constitutes another example of gamete-epididymal interaction.

Animals↗
PubMed1993

Sperm motility loss induced by gossypol: relation with OH. scavengers, motile stimulators and malondialdehyde production.

Aerobic incubation of rat spermatozoa in a balanced salt solution containing 10 microM of gossypol produced a loss of sperm motility. This effect was not reverted by the presence of 25 mM Theophylline, a well-known stimulant of motility, but was significantly diminished by the addition of 10 mM Mannitol. As mannitol is a superoxide scavenger and we found a close correlation between the loss of sperm motility and the malondialdehyde production, we concluded that gossypol affect rat spermatozoa by producing a peroxidative breakdown of membrane phospholipids.

Aerobiosis↗
PubMed1991

Interaction of Trypanosoma cruzi with macrophages influence of temperature.

The interaction of macrophages and T. cruzi has been studied in vitro culture under three different temperatures. After 24 hours incubation at 29 degree C a large number of recognizable parasites inside macrophages is observed with evidences of cell divisions. At video microscopy they show a slow motion and a predominance of epimastigotes and some round shapes (amastigotes). This was corroborated at the light and electron microscopes. No evidence of lysis in the phagosome vacuoles was observed. At 40 degrees C, macrophages show a large number of residual bodies and phagocytic vacuoles with digested parasites. At 37 degrees C, an intermediate stage with normal and digested parasites inside macrophages is observed. No significant evidences of affected phagocytic and degradative properties of the macrophages were obtained at those temperatures. It is postulated that temperature mainly affects the parasite resistance to intracellular digestion.

Animals↗
PubMed1991

Antibodies from Chagas patients serum bind to the gut epithelial cell surface of Triatoma infestans.

Serum of chagasic patients with a high title of specific antibodies against T. cruzi antigens, binds epitopes in the midgut and hindgut of the insect vector Triatoma infestans free of parasites. These antigens were recognized at ultrastructural level by immunocytochemistry with serum of chagasic patients as first antibody and protein "A"-gold as marker. Controls with normal human serum were negative. The positive reaction occurs principally in the apical epithelial portion (microvilli and peritrophic membrane) of the midgut and in the cuticular layer and adjacent cytoplasm of the hindgut. In vectors infected with trypanosomes, the antigen-antibody reaction occurs similarly in the epithelium and also in the trypanosomes present in the lumen. These results suggest that there are antigenic factors in the vector gut that are incorporated by the parasite and are recognized by the immunitary system of the human patient with production of specific antibodies.

Animals↗
PubMed1990

Sperm association in the rat epididymis.

During dissolution of drops obtained by puncture of rat epididymis in distal caput, mid corpus, proximal and distal cauda we observed in the last two regions the appearance of a new sperm association which we call rosette and the formation in the same two regions of dense clusters of non-motile degenerating spermatozoa already described in the rat vas deferens. Rosettes become organized in the proximal cauda by head to head sperm contact through a filamentous PAS positive material. By video microscopy was observed the dilution of a dense drop of cauda epididymal content in a balanced salt solution at 36 degrees C. In less than 3 min, rosettes become dispersed into single sperm with a display of intense motility which starts immediately after dilution. A glycoprotein with cohesive properties secreted by the epididymal epithelium is postulated as the factor promoting rosette formation. We confirm that dense clusters correspond to degenerating spermatozoa and describe its first appearance in the epididymal proximal cauda with increase in number toward vas deferens.

Animals↗