In vivo genotoxicity and cytotoxicity assessment of a novel quinoxalinone with trichomonacide activity.

The compound VAM2-6 (1-methyl-7-nitro-4-(5-(piperidin-1-yl)pentyl)-3,4-dihydroquinoxalin-2(1H)-one) has previously been shown to have an in vitro efficacy of 100% at a concentration of 100 µg ml(-1) against Trichomonas vaginalis, a protozoon parasite that causes the sexually transmitted disease trichomoniasis. Because VAM2-6 is a quinoxaline derivative and given the lack of studies on the genotoxic activity of this compound, the present study was undertaken to evaluate its ability to induce DNA damage in the peripheral blood of mice using single-cell gel electrophoresis (SCGE or comet assay) and the micronucleus (MN) assay. Cell viability was assessed using a fluorochrome-mediated viability test. The compound was tested on CD1 mice at 60, 40 and 10 mg kg(-1) body weight administrated intraperitoneal (i.p.) in a single dose. Peripheral blood samples were collected 24 and 48 h after treatment. N-Ethyl-N-nitrosourea (ENU) was used as a positive control for the comet and micronucleus assays. The results showed that i.p. VAM2-6 induced single-strand DNA breaks and increased the average number of micronuclei in the treated mice in a dose-dependent manner at 60, 40 and 10 mg kg(-1). Cell viability decreased at 24 h but recovered at 48 h for all three evaluated doses. Therefore, the chemical structure of VAM2-6 should be modified to reduce its genotoxic potential.

Blackwater fever like in murine malaria.

Blackwater fever (BWF) is the term used to designate the occurrence of hemoglobin pigments in the urine of patients infected with malaria parasites. BWF is more often associated with Plasmodium falciparum infection in man. The pathogenesis of BWF has not been explained satisfactorily. In the present study, the clinical and pathological observations made upon CD1 mice infected with Plasmodium yoelii yoelii lethal strain with clinical signs of hemoglobinuria and acute renal failure were evaluated. From the 40 P. yoelii yoelii-infected mice, 14 presented hemoglobinuria. In the observations, it was emphasized that hemoglobinuria occurred in the animals 1-2 days before they die. At 6 days post-infection, infected hemoglobinuric mice (HM) exhibited clinical signs such as dark red urine, apnea, and evident oliguria and hematuria; urine microscopical examination showed very few red blood cells. The entire non hemoglobinuric infected mice had a high parasitemia preceding the time of death, while the HM parasitemia was just detectable. In HM, marked hepatosplenomegaly, anemia, and renal and hepatic dysfunction were observed with the blood chemistry analysis at 6 days post-infection. Severe renal lesions were demonstrated in histopathological and scanning electron microscopy samples. Occlusion and necrosis of convoluted tubules were the main lesions found. The conditions required for the experimental production of hemoglobinuria in CD1 mouse infected by P. yoelii yoelii is still unknown. The clinical picture of a BWF, like in our rodents, was produced exclusively by the interaction between the parasite and its host. Results showed that hemoglobinuria in CD1 mice infected with P. yoelii yoelii and BWF in man infected with P. falciparum are similar in their pathogenesis.

The effect of the 5-chloro-2-methylthio-6-(1-naphtyloxy)-1H-benzimidazole on the tegument of immature Fasciola hepatica in their natural host.

The damage to the tegument of 3-week-old Fasciola hepatica was evaluated by scanning electron microscopy (SEM) following treatment with the 5-chloro-2-methylthio-6-(1-naphtyloxy)-1H-benzimidazole (called compound alpha) in its natural host. For the present study, flukes were raised in pelibuey sheep infected orally with metacercariae of F. hepatica; the parasites were recovered from the liver of the sacrificed sheep after 6, 12 and 24 h of treatment with compound alpha. At 6 h of treatment, the flukes showed some lesions on the ventral surface of the anterior region, such as a swollen tegument and blebs. At 12 h after treatment, the specimens showed structural disorganization and spine loss in the ventral anterior region. The tegument of the flukes treated for 24 h was completely lost in some areas of the ventral surface, leaving an exposed basal lamina. The tegument of immature F. hepatica might be a target organ for compound alpha to exert its fasciolicide effect.

Tegumental surface changes in adult Fasciola hepatica following treatment in vitro and in vivo with an experimental fasciolicide.

Our objective was to determine by scanning electron microscopy the structural changes in the tegument of adult Fasciola hepatica after treatment with 5-chloro-2-methylthio-6-(1-naphtyloxy)-1 H-benzimidazole, called compound alpha, and its active metabolite sulphoxide, under in vitro and in vivo conditions. For the in vitro studies, flukes from sheep were exposed to 40 mg/l of compound alpha-sulphoxide over different incubation times. Flukes for the in vivo studies were raised in sheep treated orally with compound alpha and killed at different times post-treatment. Non-treated controls were included for each time of incubation. The results showed lesions after 6 h of treatment, such as swelling and furrows. At 12 h, the spines appeared to be surrounded by the tegument. At 24 h the tegument in some areas showed an exposed basal lamina. These changes became more severe as the incubation periods of the treated flukes increased. Compound alpha exerts a significant effect on the tegument of F. hepatica.

Cinética de infección de la línea celular de macrófagos J774.2 con Histoplasma capsulatum: estudio por microscopía electronica / Infection kinetics of the macrophage J774.2 Cell-line with Histoplasma caprulatum

Se estudió la cinética de fagocitosis de levaduras de Histoplasma capsulatum en una línea celular de macrófagos (J774.2), sincronizando el inóculo y la ingestión (internalización) de levaduras a 4-C por 1h, a fin de permitir un mejor contacto de los macrófagos y las levaduras durante la fase de adherencia. La fagocitosis se llevó a cabo a 37-C con diferentes períodos de incubación 0,5,15,30,60min, 3 y 24 h, para determinar el tiempo de internalización de las células levaduriformes a los macrófagos. El seguimineto de la internalización fue realizado por microscopía electrónica de transmisión y de barrido. Se utilizó Mycobacterium tuberculosis como microorganismo de referencia. La fagocitosis de Histoplasma fue retardada en comparación con la del bacilo tuberculoso y los macrófagos (J774.2) internalizaron levaduras en un tiempo aproximado de 15-30 minutos. Mientras H. capsulatum sólo fue observado en el interior del macrófago a partir de los 15 min de fagocitosis, M. tuberculosis fue encontrado desde los 0-5 minutos. Además, a los 60 min aún se observaron levauras adheridas, siendo que los macrófagos infectados con M. tuberculosis presentaron daño y muerte celular. Estos resultados apoyan las diferencias en la internalización de ambos microorganismos