J. Pérez-Serrano

The effects of albendazole and albendazole sulphoxide combination-therapy on Echinococcus granulosus in vitro

Protoscoleces of Echinococcus granulosus were incubated in vitro with decreasing concentrations of either albendazole (ABZ) or albendazole sulphoxide (ABZ.SO) (50, 10, 1 and 0.1 micrograms ml-1), and in combination. Viability was assessed by the methylene blue exclusion test and establishment of infection in mice. Protoscolex ultrastructure was determined by means of transmission and scanning electron microscopy. ABZ and ABZ.SO, when used separately had protoscolicidal activity after a longer incubation period (30 days) than when used as combined compounds. When incubated in the presence of ABZ + ABZ.SO, protoscolex viability dropped rapidly. That is, protoscoleces were all non-viable at 12 days of exposure, with no cyst developing following their inoculation into mice. The ultrastructural changes induced by ABZ or ABZ.SO alone, were: (a) rostellar disorganization, (b) formation of numerous blebs on the tegument, (c) loss of the microtriches, (d) increased vesiculation within the tegumentary cytons together, (e) an increase in lipid deposits and (f) depletion of glycogen reserves. After incubation with combined ABZ and ABZ.SO the tegument contained numerous blebs which became detached, leaving debris only, some intact nuclei being discernible in the protoscolex parenchyma.

Development of a chemotherapeutic model for the in vitro screening of drugs against Echinococcus granulosus cysts: the effects of an albendazole-albendazole sulphoxide combination

This paper describes a novel experimental model for the screening of putative drugs against the metacestode stage of E. granulosus using hydatid cysts derived from in vitro culture of protoscoleces. The effects of an ABZ+ABZ.SO combination against cultured and murine cysts were studied with this in vitro model system. This treatment produced loss of turgidity of the cultured cysts in less time than in the murine cysts but the ultrastructural tissue damage observed in both cultured and murine cysts was similar. The ultrastructural changes induced by ABZ+ABZ.SO were: (i) vacuolation of the distal cytoplasm that extended to the tegumentary cells of the germinal membrane; (ii) increased number of mitochondria; (iii) partial loss of microtriches; (iv) increased number of autophagosomes; and (v) an increase in lipid deposits.

Carbosilane cationic dendrimers synthesized by thiol–ene click chemistry and their use as antibacterial agents

Cationic carbosilane dendrimers of generations 1–3 have been synthesized employing thiol–ene click chemistry. The obtained dendrimers present three different types of ammonium functions, two of them with the charge at the surface, –NH3+ and –NMe3+, and other with the charge internalized by the presence of ethylalcohol moieties, –[NMe2(CH2CH2OH)]+. The influence of –NMe3+ and –[NMe2(CH2CH2OH)]+ in dendrimer structure have been studied by molecular dynamics. The antibacterial properties of these families of dendrimers have been evaluated against Gram-positive (Staphylococcus aureus CECT 240) and Gram-negative (Escherichia coli CECT 515) bacterial strains, and the results have been compared with those obtained for related cationic carbosilane dendrimers functionalized by hydrosilylation reactions. These data show the relevance of the sulfur atom versus the silicon atom close to the dendrimer surface and the outer charge versus the inner charge. Finally, the stability of the most active first generation dendrimers vs. pH and temperature has also been studied.

In vivo effect of oral albendazole and albendazole sulphoxide on development of secondary echinococcosis in mice

This paper describes the effectiveness of ABZ, ABZ.SO and ABZ + ABZ.SO treatment in mice infected with Echinococcus granulosus protoscoleces. The results were evaluated in two ways: measuring the number and wet weight of developed cysts and by transmission electron microscopy (TEM) of tissue cyss. ABZ and ABZ + ABZ.SO had an important effect upon larval growth in E. granulosus. The ultrastructural changes noted were: vacuolation of tegumentary cells of the germinal membrane; increased number of mitochondria; increased number of autophagosomes and an increase in lipid deposits.

Viability of Echinococcus granulosus cysts in mice following cultivation in vitro

The viability of hydatid cysts developed in vitro for 90 days was assessed by implantation into mice. Cysts removed from mice at 270 days post-infection (p.i.) increased their size 13.5-fold and contained several brood capsules containing protoscoleces. Thus, cysts remain viable after prolonged in vitro culture. The implantation in mice of 15 cysts developed in vitro yielded an average of 10 cysts per mouse, which is indicative of a high survival rate in these experimental infections. The ultrastructural study of cysts recovered from mice 270 days p.i. showed that the germinal membrane was more compact than before implantation and several layers of tegumental cells had developed. Observations of cysts removed from mice indicated that the plasma membrane surrounding microtriches had prolongations opening into the laminated layer.

Trophozoites of Entamoeba histolytica express a CD59-like molecule in human colon

In vitro studies have proved the presence of epitopes of CD59 in the surface of trophozoites of Entamoeba histolytica (E. histolytica). However, it has not been proved if CD59 molecules are expressed in the surface during the trophozoites’ tissue invasion. The aim of the present study was to determine whether the complement-regulatory protein CD59 is present on trophozoites of E. histolytica in human colon. Eleven specimens of amoebic colitis were studied by immunohistochemistry and electron microscopy techniques with a monoclonal antibody against human CD59 molecule. Our results show that a CD59-like molecule is expressed in trophozoites of E. histolytica found in colonic amebic lesions. Also, a CD59-like molecule was detected by western blot analysis in whole lysate of E. histolytica as well as on the plasma membrane by immunocytochemistry. These results suggest that E. histolytica can use CD59-like protein against the lytic action of membrane attack complex.

Bertiellosis in man: a review of cases

The presence of Bertiella mucronata and Bertiella studeri (Cestoda: Anoplocephalidae) in humans is reviewed, and international infection rates and a bibliography included. Taxonomic, biological, epidemiological, pathological, diagnostic, control, prevention and therapeutic aspects of the zoonosis are analyzed, and the increase in zoonotic potentiality of the parasitosis is discussed.

In vitro comparative assessment of different viability assays in Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites

The species of the genus Acanthamoeba are opportunistic protozoan parasites that cause different diseases in humans, such as amoebic keratitis and granulomatous encephalitis. The rise in the rate of Acanthamoeba keratitis, mainly due to the increase in contact lens wearers, turns the development of viability assays using a multi-well plate reader as a tool for screening new antiamoebic agents in vitro into an important goal. In our study, the viability assays PrestoBlue®, resazurin sodium salt, 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) and CellTiter96® were tested for their suitability as time-saving alternatives to the classical manual or direct-counting method, assessing the effect of the antiamoebic agent chlorhexidine digluconate and temperature on Acanthamoeba castellanii (ATCC® 30234™) and Acanthamoeba polyphaga 2961. Although resazurin and MTT have already been previously used in amoeba viability assays to test the activities of antiamoebic agents in vitro, it is the first time that PrestoBlue® and CellTiter96® are used for this purpose. Results indicated that the viability assays were strain-dependent leading in some cases to an overestimation of the real situation of viable cells. This implies that each viability assay ought to be set up for each amoeba strain studied.

Ultrastructural alterations induced by nifurtimox and another nitro derivative on epimastigotes of Trypanosoma cruzi.

Abstract. We report the ultrastructural alterations induced on epimastigotes by nifurtimox and 5-nitro-2-thienyl-malononitrile (5NO2TM), a novel compound with anti-Trypanosoma cruzi activity. Parasites treated with concentrations of nifurtimox lower than usually employed for this kind of study showed vacuolisation, alterations of the mitochondria, the nucleus and the ribosomes. 5NO2TM caused the same kind of damage, but to a greater degree. This result correlates with the fact that cultures treated with this compound experienced a greater loss of viability.

In vitro anti-Acanthamoeba synergistic effect of chlorhexidine and cationic carbosilane dendrimers against both trophozoite and cyst forms

Acanthamoeba sp. are the causative agents of severe illnesses in humans such as Acanthamoeba keratitis (AK) and granulomatous amoebic encephalitis (GAE). Medical therapy is not yet well established. Treatments of AK last for several months and generate toxicity, resistances appear due to the cysts stage and recurrences can occur. In this study has been demonstrated that the combination of chlorhexidine digluconate (CLX) and carbosilane dendrimers containing ammonium or guanidine moieties has in vitro synergistic effect against Acanthamoeba polyphaga. This synergy provokes an important reduction in the minimal trophozoite amoebicidal concentration (MTAC) of CLX, which means a reduction of their toxic effects on human cells. Moreover, some CLX/dendrimer combinations show important activity against the cyst resistance stage.