System of 14C-glucose incorporation in axenic cultures of Entamoeba invadens: IP-1 strain.

BACKGROUND: It has been described that the walls of the amebic cysts from Entamoeba invadens are composed mainly of chitin, a polysaccharide of amino-sugars. It is also known that the synthesis of this polysaccharide is closely related to the degradation of the intracellular glycogen in this organism. Nevertheless, it is not known whether the intracellular glycogen is really the source of the glucose requirements for the synthesis of the cell wall. METHODS: To determine the relationship between the wall cyst synthesis and glycogen degradation, it was considered to develop an in vitro culture cell system to label this polysaccharide with radioactive glucose. In this study, a system of 14C-glucose incorporation in axenic cultures of E. invadens was developed. The experiments in the study were carried out to recognize if an increase occurred in the 14C-glucose incorporation into ameba when the amount of the radioactivity used was increased, or whether this incorporation is a dependent metabolic stage. RESULTS: The results showed that the amount of glucose incorporation reached similar values of 4.5 x 10(-12) mmol per cell in both cases. A different slope in the glucose kinetic incorporation between the cultures previously subjected to glucose depletion and the standard cultures was observed. CONCLUSIONS: This axenic method of radioactive glucose incorporation in Entamoeba invadens could facilitate the analysis on a greater scale of the metabolism of this nutrient.

[Determination of cytoplasmic glycogen in 4 strains of amoeba of the genus Entamoeba]. / Determinación de glucógeno citoplasmático en cuatro cepas de amibas del género Entamoeba.

The purpose of this work was made to determine the cytoplasmic glycogen concentration in trophozoites from four different strains of Entamoeba genus. We used IP-1 and PZ from E. invadens; HM-2 and HK-9 from E. histolytica strains, axenically cultured in TP-S-1 medium. The growth of different strains was determined each 24 hours during 10-days, with the aid of a hemocytometer. The quantification of cytoplasmic glycogen was made by two methods: 1) Montgomery and 2) Krisman. The glycogen concentrations were measured in the four strains during their growing. The results did not show any difference, remained as a constant concentration in each strain. These concentrations quantified by Montgomery method were similar in all strains (35 pg/cell), except in HM-2 strain which showed a less concentration of this polysaccharide (28 pg/cell) than the other strain. These results were different when Krisman method was used, both IP-1 and PZ strains had a similar glycogen concentrations about 19 pg/cell, however HM-2 and HK-9 strains had a higher glycogen concentration (21 pg/cell) than E. invadens strains.

[Growth inhibition of Entamoeba histolytica and E. invadens produced by pomegranate root (Punica granatum L.)]. / Inhibición del crecimiento de Entamoeba histolytica y E. invadens producida por la raíz del granado (Punica granatum L.).

The purpose of the present work has been to evaluate the biological activity of alkaloids and tannins extracted from roots of Punica granatum L. on axenic cultures from Entamoeba histolytica and E. invadens, strains. Initially, the total aqueous extract and later some of its components obtained by thin layer chromatography were tested. These compounds were identified by chromatography as alkaloids or tannins. The density of amebic cultures was determined with a hemocytometer after 48 and 96 hours of incubation, which was calculated by the difference between number of trophozoites obtained at the times chosen and the number of amoebae inoculated. Two milliliters of aqueous extract had higher activity on cultures from E. histolytica than E. invadens strains, producing growth inhibitions of about 100 and 40 per cent respectively. Alkaloid concentrations of 1 mg/ml had no amebicide activity, however tannins at concentrations of 10 micrograms/ml for E. histolytica, and 100 micrograms/ml for E. invadens were sufficient to produce an growth inhibition about 100 per cent. Tannic acid was also tested on the cultures of E. histolytica observing an high inhibitory activity on the growth, this effect was produced at 0.01 mg/ml was similar to that observed with the tannins mixture.

Division nuclear y presencia de microtubulos en la diferenciacion de Entamoeba invadens. / Nuclear division and presence of microtubules in the differentiation invadens

El curso de la division nuclear, asi como el tiempo en el que ocurren las divisiones nucleares durante la diferenciacion de Entamoeba invadens IP-1 fueron estudiados a traves de microscopia optica y microscopia electronica. Las divisiones nucleares ocurrieron entre las 28 y 32 h de iniciado el enquistamiento, alcanzando una maxima proporcion de aproximadamente 50 por ciento a las 30 horas.Durante la division nuclear es carecteristica la presencia de una estructura central densa que desaparecee antes de la metafase y alrededor de la cual se inicia la condensacion de cromatina. Los cromosomas, atipicos en relacion a los de eucariotes superiores, son evidentes particularmente durante la anafase. Condensaciones de cromatina asociadas a la membrana nuclear no participan en la formacion de cromosomas y la membrana nuclear permanece intacta durante todo el proceso de division nuclear. Existe la formacion de un huso intranuclear formado por microtubulos de aproximadamente 240 A de diametro. No fueron detectados centriolos

Rhinoentomophthoromycosis: report of the first two cases observed in Costa Rica (Central America), and review of the literature.

The first two cases of rhinoentomophthoromycosis to be recognized in Costa Rica are reported. The first patient was a 32-year-old Caucasian male from the Pacific Coast, and the second, a 17-year-old Negro male from the Atlantic Coast. Both cases showed the typical involvement of the nasofacial skin with the formation of subcutaneous nodules. One patient also showed left maxillary sinus involvement. Both patients were in general good health, without any associated disease. Cultures from the second patient, taken from the glabellar nodule, were positive for Conidiobolus coronatus. These two cases represent the first documentation of this uncommon mycosis in Central America.

[Effects of nordihydroguairetic acid and ethanol on the growth of Entamoeba invadens]. / Efectos de ácido nordihidroquayarético y etanol sobre el crecimiento de Entamoeba invadens.

The effects of the alcoholic extract (resin) obtained from Larrea tridentata, of nordihydroguiaretic acid (NDGA) and of ethanol over axenic cultures of Entamoeba invadens PZ strain were studied. The activity of these substances was demonstrated in growht curves. Inocula of 1-3 x 10(5) trophozites by milliliter in culture tubes containing 11 ml of TP-S-1 medium were done, and incubated at 25 degree C. In each experiment the follwoing was done: a) tipical growth curve as a control, b) curve with the medium plus 0.2 ml of a mixture of ethanol and water v/v (solvent used for resin and NDGA), and c) curves with different concentrations of the test compounds. The trophozoite number was counted each 24 hours by means of an hemocitometer. The results obtained indicate that the resin has inhibitory activity at a concentration of 0.0001 per cent. The NDGA activity was observed at 10(-6) to 10(-8) M concentrations. The ethanol had, "per se", inhibitory effect over the cultures, and was annulated by the presence of NDGA. At higher contentrations of the acid acid the temporal curse of the graphas was similar to that observed for the control.