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C Argüello

Publications and source records attributed to C Argüello.

At least 37 records · Page 2Linked to original sources
PubMed1986

Electrophysiological and ultrastructural study of the atrioventricular canal during the development of the chick embryo.

The development of the atrioventricular canal (A-V canal) of embryonic chick hearts (35 to 120 h) was studied by morphological and electrophysiological techniques. The earliest identification of the A-V canal action potentials was at 45 to 49 h of incubation coinciding with the atrium formation and the appearance of its corresponding distinctive action potential. At that time the first atrioventricular delay was recorded and its action potentials showed a low rate of rise, particularly at the initiation of the upstroke and a long duration. The conduction velocity was the lowest in the A-V canal. As the development proceeded from 45 to 120 h, the cardiac cells of the A-V canal showed scanty membrane to membrane contacts and large intercellular spaces filled with abundant extracellular matrix components, in striking contrast to the paucity of these components in the atrium and ventricle. The morphological and electrophysiological characteristics described for the A-V canal cells, could help to explain their slow conduction properties and the atrioventricular delay.

Animals↗
PubMed1985

Leishmania braziliensis: cell surface differences in promastigotes of pathogenic and nonpathogenic strains.

A comparative study of cell surface characteristics of pathogenic and nonpathogenic promastigotes of Leishmania braziliensis, NR and LBY strains, respectively, was carried out by means of concanavalin A agglutination and labeling with concanavalin A-fluorescein isothiocyanate, concanavalin A-ferritin, and cationized ferritin. Cytochemical examination showed cell surface differences in lectin receptors and negative charge moieties in the two strains of L. braziliensis. The pathogenic NR strain agglutinated with low concentrations of concanavalin A and presented abundant lectin-binding and cationized ferritin-binding surface labeling. The nonpathogenic LBY strain neither agglutinated when incubated with concanavalin A, bound lectins, or cationized ferritin at the cell surface.

Agglutination↗
PubMed1984

Ultrastructural study of the myocardial wall of the atrio-ventricular canal during the development of the embryonic chick heart.

In the early stages of chick embryo development (days 3-5) the myocardium of the atrio-ventricular canal (AV) is continuous with the atrial and ventricular muscles; however, interruption of muscular continuity is observed at later stages (from day 6 to day 8). The most relevant event occurring at the AV canal region is the dissociation of the myocytes due to the loss of their cellular attachments, rather than an invasion of connective tissue cells (endocardial and sub-epicardial) located on both sides of the myocardium. In this study, particular attention was paid to the sequential changes that take place in the myocardium of this region, these being (1) a reduction in the number of desmosomes and intercalated discs with the subsequent appearance of large, inter-cellular spaces between myocytes; (2) migration of these cells through a complex extra-cellular matrix, to which it appears to be closely related, suggesting that the macromolecules of this matrix may be being synthesized by the myocytes, and may take part in the process of cardiac cell separation; (3) incorporation of the myocytes in the developing tricuspid valve, where they co-exist with fibroblasts. The results of the study correspond remarkably well to those previously carried out on the left AV canal myocardium, suggesting that the behaviour of the muscle is the same, at all points around the AV canal.

Animals↗
PubMed1984

Extracellular matrix production by mouse 3T3-F442A cells during adipose differentiation in culture.

When cultured 3T3-F442A cells undergo adipose differentiation, they produce extracellular matrix (ECM) that is not present in undifferentiated cells. This ECM stains strongly with ruthenium red, tannic acid and with Alcian blue at both pH 1 and 2.5, showing histochemical characteristics similar to sulphated and non-sulphated glycosaminoglycans. Under the electron microscope, ECM was observed bound to the cell surface and in the intercellular space; it was composed of fibrils of several thicknesses with attached granules and fibrous long-spacing forms of collagen. In addition, adipocytes were observed as rounded cells interconnected with the ECM fibrils, thus giving rise to fat cell clusters similar to the adipocyte lobules found in adipose tissue. Since fat cell clusters in culture emerge by clonal expansion of one adipose precursor cell, we suggest that this ECM can keep daughter adipocytes interconnected during differentiation. ECM production by adipocytes might have some significance for the formation of fat cell lobules in vivo.

Adipose Tissue↗
PubMed1977

Surface properties related to concanavalin A-induced agglutination. A comparative study of several Entamoeba strains.

Pathogenic strains of Entamoeba histolytica are more easily agglutinated with concanavalin A (Con A) than strains isolated from human asymptomatic carriers. All three pathogenic strains studied here were found to agglutinate with low concentrations of Con A in contrast to various nonpathogenic axenic strains of amebas, characterized by their ability to grow at room temperature. Our present observations suggest that the extreme susceptibility of pathogenic strains of E. histolytica to agglutinate with Con A is related to their higher capacity for lectin binding and to their lack of detectable repulsive charges at the cell surface. The amount of fluorescein-tagged Con A bound to the surface was much higher in pathogenic strains. Only nonpathogenic strains showed a detectable negative surface charge as studied both by means of cell microelectrophoresis and by labeling cells with cationized ferritin at 0 degrees C. The mobility of surface Con A receptors estimated as the percentage of caps was comparable in all strains. Results of one strain cultured in axenic and monoxenic conditions suggested that bacteria can modify the behaviour of E. histolytica trophozoites by altering surface properties of the amebas.

Agglutination Tests↗
PubMed1977

Experimental study of the development of the truncus and the conus in the chick embryo.

The development of the truncus and the conus was studied in the chick embryo by in vivo labelling techniques. The earliest labels were placed at the stage of fusion of the myocardial troughs (stage 9-) and they were traced until the mature heart stage (stage 35). Microdissections and light microscopic studies were also carried out. The results are discussed in relation to the human heart. Our experiments permit the following conclusions: (1) At stage 9- fusion of the myocardial troughs takes place at the level of the primordium of the trabeculated portion of the right ventricle, when neither the conus nor the truncus are present. (2) At stage 12 (loop stage) there appears the caudal portion of the conus, which constitutes the cephalic end of the cardiac tube. (3) The truncus appears between stages 13 and 22. (4) At stage 22 angular junction between the conus and the truncus is the area where the semilunar valve cusps of the great arteries will develop and that, at this same stage, the junction between the conus and the trabeculated portion of the right ventricle seen from the right surface corresponds to the inferior edge of the crista supraventricularis. (5) It was confirmed that the pulmonary semilunar valve cusps originate from the walls of the truncus. (6) The development of the conus and truncus are similar in chick and man. (7) Histologically, in the chick, the wall of the truncus and the conus contain cardiac muscle as late as stage 28, but from then on the walls of the truncus are transformed into connective tissue and plain muscle.

Animals↗
PubMed1975

Experimental study of the formation of the heart tube in the chick embryo.

A study was made of the development of the heart tube beginning from Hamburger & Hamilton (1951) stage 8+ up to stage 12. We used labelling with particles of iron oxide followed with time-lapse cinemicrophotography, staining with methylene blue, serial section and cutting the embryo in two halves. Our results led to the conclusion that the tubular heart is formed by the addition of precardiac material into its posterior end, but in addition it is necessary to consider the fusion of the myocardium in a cephalic direction, starting with the fusion of both heart primordia at the rostral end. By this fusion the most anterior part of the heart up to stage 12 is formed.

Animals↗
PubMedDate not supplied

Giardia lamblia: surface charge of human isolates in culture.

The surface charge of Giardia lamblia trophozoites from axenic cultures of strains recently isolated in Mexico from human cases of symptomatic and asymptomatic giardiasis was studied by means of cellular microelectrophoresis and ultrastructural cytochemistry. It is concluded that ionogenic surface groups confer a negative surface charge on trophozoites of G. lamblia and that no significant differences exist between the surface charge of trophozoites of symptomatic and asymptomatic origin.

Animals↗
PubMedDate not supplied

Entamoeba dispar: ultrastructure, surface properties and cytopathic effect.

The cytological features of Entamoeba dispar, recently recognized by biochemical and molecular biology criteria as a distinct species, were compared to those of Entamoeba histolytica When cultured under axenic conditions, living trophozoites of E. dispar strain SAW 76ORR clone A were more elongated in form, had a single frontal pseudopodium, and showed a noticeable uroid. In sections of E. dispar trophozoites stained with Toluidine blue, characteristic areas of cytoplasmic metachromasia were seen due to the presence of large deposits of glycogen, seldom found in E. histolytica strain HM1:IMSS. Under the light microscope the periphery of the nucleus in E. dispar was, lined by finer, more regularly distributed dense granules. With transmission electron microscopy the surface coat of E. dispar was noticeable thinner. In addition. E. dispar had a lower sensitivity to agglutinate with concanavalin A and a higher negative surface charge, measured by cellular microelectrophoresis. The cytopathic effect of E. dispar was much slower, analyzed by the gradual loss of transmural electrical resistance of MDCK epithelial cell monolayers mounted in Ussing chambers. Whereas in E. histolytica phagocytosis of epithelial cells plays an important role in its cytopathic effect. E. dispar trophozoites placed in contact with MDCK cells showed only rare evidence of phagocytosis. The results demonstrate that the morphology of E. dispar is different to that of E. histolytica, both at the light microscopical and the ultrastructural levels. In addition they show that E. dispar in axenic culture has a moderate cytopathic effect on epithelia] cell monoLayers. However, when compared to E. histolytica, the in vitro lytic capacity of E. dispar is much slower and less intense.

Agglutination↗
PubMedDate not supplied

Hemophagocytic syndrome as an unusual form of presentation of tuberculosis in a hemodialysis patient: case report and review of the literature.

We present an unusual manifestation of tuberculosis in a patient on hemodialysis. A 73-year-old woman was admitted to our hospital with a picture of fever, dyspnea and weight loss. She had chronic renal failure and had started periodic hemodialysis 5 years before. Fifteen days after admission, she began with pancytopenia, abnormal liver function and coagulopathy. A bone marrow aspiration was made 1 week later showing macrophage elements with phagocytic activity. Eight weeks later, bone marrow culture in Lowenstein media confirmed the presence of tuberculosis. After the beginning of antituberculosis therapy, the laboratory disturbances disappeared and the clinical situation improved. We think that fever of unknown origin and pancytopenia in patients on maintenance hemodialysis must lead to an early bone marrow biopsy or aspiration since after the diagnosis a specific therapy can cure the disease.

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