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Biomedical subjects

M Chinchilla

Publications and source records attributed to M Chinchilla.

At least 19 recordsLinked to original sources
PubMed2000

[Parasitic helminths from Sigmodon hispidus (Rodentia: Cricetidae) from seasonal and evergreen habitats in Costa Rica].

The helminthological fauna of the cotton rat, Sigmodon hispidus in a tropical environment varies according to habitat and feeding behavior. Six species of nematodes (Longistriata adunca, Trichostrongylus sigmodontis, Strongyloides sigmodontis, Litomosoides carinii, Monodontus sp. and Protospirura sp.) and two species of cestodes (Hymenolepis diminuta and Raillietina sp.) were found in rats from extensive dry lands in Guanacaste where hot temperatures and heterogeneous diet are the rule. Only two species of nematodes (Longistriata adunca and Angiostrongylus costaricensis) were found in rats collected in a humid pineapple plantation in the Central Plateau (Alajuela) where mild temperatures predominate. A. costaricensis, a metastrongylid of medical importance, was found in 42% of them.

Animals↗
PubMed1999

Visceral leishmaniasis in Costa Rica: first case report.

We describe a 15-month-old eutrophic immunocompetent male who presented with fever, hepatosplenomegaly, pancytopenia, and hypergammaglobulinemia. Leishmania amastigotes were identified in spleen and bone marrow specimens. In addition, tissue culture, animal inoculation, and isoenzyme analysis identified the parasite as Leishmania donovani infantum or Leishmania donovani chagasi. The infant was successfully treated with an antimonial drug. These findings represent the first case of visceral leishmaniasis reported in Costa Rica.

Animals↗
PubMed1999

Infection of white rat peritoneal macrophages with Toxoplasma gondii, (Coccidia: Sarcocystidae) after Trypanosoma lewisi (Kinetoplastida: Trypanosomatidae) infection.

Peritoneal macrophages from Wistar rats, inoculated and non-inoculated with 10(6) T. lewisi trypomastigotes, were cultured and infected with 10(6) T. gondii tachyzoites. Multiplication rates of this parasite were studied after 1, 24 and 48 h of infection but there were not significant differences between the number of parasites found inside of macrophages coming, either from T. lewisi infected or non infected rats. On the other hand, in vivo studies of Toxoplasma multiplication inside peritoneal macrophages, showed that there is an increase of parasite number in cells from T. lewisi infected rats, as compared with those macrophages from non infected rats. This effect was statistically significant and was more evident after four days of infection. Therefore, it has been demonstrated that in vivo, but not in vitro T. lewisi infections, causes an important decrease of the natural resistance to T. gondii of the white rats, which is manifested by the major invasion and multiplication of the parasite inside of peritoneal macrophages.

Animals↗
PubMed1998

An in vivo model to study the anti-malaric capacity of plant extracts.

An in vivo model to study the antimalaric effect of plant extracts is described. White mice (25-30 g body weight) are treated subcutaneously with 0.6 ml of the diluted extract starting seven days before P. berghei infection; treatment continues until death or for 30 days. Simultaneously 0.2 ml of the extract are applied per os starting three days before infection. In a test of the model, treated and non-treated animals differed in body weight, survival time, haematocrite, parasitemia development, and spleen or liver weight of recent dead or killed mice.

Animals↗
PubMed1997

Toxoplasma gondii (Eucoccidia: Sarcoystidae) dissemination pattern in rats after oral infection with oocysts of an avirulent strain.

Differences in Toxoplasma gondii dissemination in white rats (Sprague Dowley) and mice (Wistar) after oral oocyst inoculation are described. Groups of five animals (both hosts) were infected per os with oocysts of the TCR-2 avirulent strain and the dissemination pattern was compared in brain tissue or by serology. Early dissemination was similar in both species. One hr after infection the parasite was present in blood and peritoneal exudate as well as in heart, lung, liver, spleen, lymph nodes and brain. However, after five days there were important differences between both hosts and after 30 days, the parasite was detected only in rat heart and brain, while in mice it persisted in fluids and all organs.

Animals↗
PubMed1997

Increasing of Toxoplasma gondii (Coccidia, Sarcocystidae) infections by Trypanosoma lewisi (Kinetoplastida, Trypanosomatidae) in white rats.

To demonstrate that T. lewisi infection increases T. gondii multiplication in white rats, groups of five Wistar or Sprague Dawley rats were inoculated with 10(6) T. lewisi trypomastigotes and four or seven days later infected with Toxoplasma tachyzoites. Host survival time was monitored, and the presence of T. gondii was confirmed in all dead rats by studying peritoneal exudate smears and lung tissue sections stained with haematoxylin-eosin. The presence of Toxoplasma cysts or antibodies was checked in the brain of surviving rats. The increase is observed four days after trypanosome inoculation and is dependent on rat strain, but not on inoculum size or rat age. Humoral and cellular factors may have a role in the increase as has been reported for other experimental infections with African trypanosomes and T. cruzi.

Animals↗
PubMed1997

[A simple method for determining the presence of Toxoplasma gondii (Eucoccidia: Sarcocystidae) in meat].

Presence of T. gondii in meat from several sources was determined by traditional methods and by a new simplified method in which animals are fed meat directly without any previous treatment with artificial gastric fluid. Tissues are ground and the animals ingest them naturally. Determination of Toxoplasma in lungs or brain (as well as by specific antibody test), showed no statistically significant differences between both methods.

Animals↗
PubMed1996

Anticryptococcal activity by alveolar macrophages from rats treated with cortisone acetate during different periods of time.

The effect of cortisone acetate (CA) treatment on the anticryptococcal activity by rat alveolar macrophages (AM) was investigated. The animals received a weekly dose of 5 mg CA during 1, 2, 3 or 4 weeks. Following the final dose the AM were collected by lung lavage and challenged with Cryptococcus neoformans. Parallel experiments with silica particles of a similar size were performed. The phagocytic function was assessed using a fluorescence method that distinguishes between attached and ingested particles. The oxidative metabolism was studied by the nitroblue tetrazolium (NBT) reduction test. The accumulated attachment (a measure of the attachment process) of cryptococci and silica particles per AM was significantly depressed after the third and fourth week of CA treatment. The ingested fraction (a measure of the ingestion process) of cryptococci but not of silica particles showed a small but significant decrease after the fourth week. The NBT reduction of the unstimulated AM and those stimulated with either the cryptococci or silica particles for 24 h was significantly reduced after the fourth week of treatment. In conclusion, these results demonstrate that high dose CA treatment primarily affects the attachment of the cryptococci to the AM and to a lesser extent also the ingestion process. In addition, it decreases the NBT reduction by AM in response to the yeast. The impairment of the AM anticryptococcal activity by high doses of CA constitutes a risk of dissemination of C. neoformans from the lungs.

Animals↗
PubMed1996

[Susceptibility of Sigmodon hispidus (Rodentia: Cricetidae) to Toxoplasma gondii (Eucoccidia: Sarcocystidae)].

Sigmodon hispidus, a cotton rat, was inoculated with tachyzoites or oocysts of Costa Rican strains of Toxoplasma gondii to demonstrate the resistance to this parasite, as compared with mice, hamster and white rat infection. Susceptibility to tachyzoite inoculation was higher in this animal than in white rats but lower than in the other animals. Independent to the Toxoplasma strain studied, oocyst infection was less lethal for S. hispidus when compared with mice and hamsters; the results were similar to those observed for white rats. There is a probable participation of this wild animal in the natural Toxoplasma life cycle.

Animals↗
PubMed1996

[Chemical and biological evaluation of the effect of plant extracts against Plasmodium berghei].

Extracts from thirteen species of plants were evaluated by "in vivo" antimalarial test against plasmodium berghei effects. Significant activities were observed in the ethyl acetate and aqueous extracts, elaborated of Cedrela tonduzii leaves, Trichilia havanensis and Trichilia americana barks, Neurolaena lobata and Gliricidia sepium leaves and Duranta repens fruits. Compounds identified include flavanoids, coumarins, mellilotic acid and iridoids which some kind of biodynamic activity has previously been reported. The flavone quercetin 1 purified from C. tonduzii gave strong antimalarial activity, however, its respective glucosides (quercetin 3-glucoside 2 y robinine 7) showed little significant activity.

Animals↗
PubMed1996

[Seasonality of parasites and intestinal bacteria in vegetables that are consumed raw in Costa Rica].

In Costa Rica, a total of 640 samples from eight different vegetables used for raw consumption, were analyzed for the presence of intestinal parasites and fecal coliforms. Eighty samples of each vegetable were analyzed, forty during the dry season and forty in the rainy. A greater, but unsignificant (p > 0.05) level of fecal coliforms was found during the dry season. Levels of Escherichia coli, were higher (p < 0.05) during the dry season in lettuce (Latuca sativa) and cilantro (Coleandrum sativum) leaves. Cysts of Endolimax nana, Entamoeba coli, Entamoeba histolytica, Giardia intestinalis and Cryptosporidium sp. were found in all vegetables. The greater percentage of positive samples was found during the dry season, although these relation was only corroborated (p < 0.05) in radish (Raphanus sativus) and cilantro leaves. Only lettuce and cilantro levels showed a positive linear correlation (p < 0.05) between occurrences of intestinal parasites and fecal coliforms.

Animals↗
PubMed1996

Seroepidemiology of toxoplasmosis in humans: possible transmission routes in Costa Rica.

A serological survey with immunofluorescence techniques to detect toxoplasma antibodies was done on a sample of 1234 Costa Ricans. The overall prevalence was 76%; it increased from 60% in donors aged 1-4 years to 90% in those over 25 years. No significant difference was found in seropositivity between males (42.8%) and females (57.2%) and between donors from urban and rural (LPI) areas. Consumption of raw meat, especially prepared meat, was significantly correlated with antibody prevalence, but cat contact was not, indicating a possible change in the usual pattern of transmission described for the country. Nevertheless, our data suggest that infectious cat feces play an important role in the transmission of toxoplasmosis.

Adolescent↗
PubMed1994

Determination of Toxoplasma gondii in several organs of cattle by carbon immunoassay (CIA) testing.

Samples of muscle, heart, liver and lung were tested for the presence of Toxoplasma gondii using mice as a biologic detector and the carbon immunoassay (CIA) for immunological diagnosis. In positive tissues the percentage of samples positive ranged from 10 to 50% which indicates the importance of cattle in the epidemiology of Toxoplasma in Costa Rica. We discuss these findings in relation to the transmission of the parasite in Costa Rica.

Animals↗
PubMed1993

Natural and induced blood dissemination of Toxoplasma gondii: experimental model in white mice and hamsters.

Blood inoculation in mice showed that Toxoplasma organisms circulate in blood after 1 h of oocyst infection. Parasites were detected up to 15 days later and then disappeared from the bloodstream concomitantly with cyst formation in the brain, probably due to antibody presence. Immunosuppression caused by cortisone acetate treatment induced Toxoplasma bloodstream invasion in chronically infected mice and hamsters, causing death in some. Natural dissemination is discussed in relation with congenital toxoplasmosis. Induced immunosuppressive effect is compared with that produced by natural diseases such as Hodgkin, lymphoma, AIDS and others.

Animals↗
PubMed1992

Specificity of the carbon immunoassay (CIA) test for the diagnosis of Toxoplasma infections.

A rapid and low cost procedure, the carbon immunoassay (CIA) test, was evaluated for the diagnosis of Toxoplasma gondii infections. Using a closely related parasite (Besnoitia jellisoni) as antigen, and homologous or heterologous immune sera, it was demonstrated by light and electron microscopy that CIA is a very reliable and specific test. As it is neither expensive nor time-consuming, it can be recommended for general and routine laboratory use.

Animals↗