The Declaration of Sydney on human death

On 5 August 1968, publication of the Harvard Committee's report on the subject of "irreversible coma" established a standard for diagnosing death on neurological grounds. On the same day, the 22nd World Medical Assembly met in Sydney, Australia, and announced the Declaration of Sydney, a pronouncement on death, which is less often quoted because it was overshadowed by the impact of the Harvard Report. To put those events into present-day perspective, the authors reviewed all papers published on this subject and the World Medical Association web page and documents, and corresponded with Dr A G Romualdez, the son of Dr A Z Romualdez. There was vast neurological expertise among some of the Harvard Committee members, leading to a comprehensible and practical clinical description of the brain death syndrome and the way to diagnose it. This landmark account had a global medical and social impact on the issue of human death, which simultaneously lessened reception of the Declaration of Sydney. Nonetheless, the Declaration of Sydney faced the main conceptual and philosophical issues on human death in a bold and forthright manner. This statement differentiated the meaning of death at the cellular and tissue levels from the death of the person. This was a pioneering view on the discussion of human death, published as early as in 1968, that should be recognised by current and future generations.

Recognizing a mother's voice in the persistent vegetative state

We studied an 8-year-old boy after a near-drowning left him in a vegetative state (VS) for 4 years before the study. Findings fulfilled all clinical criteria for the diagnosis of VS. The purpose of this study was to investigate whether there was significant differential activation of the brain in response to hearing his mother's voice compared with the voices of unknown women. The data were assessed using quantitative electric tomography (QEEGt), a technique that combines anatomical information of the brain by MRI with EEG patterns to estimate the sources of the EEG within the brain. We found significant differences for EEG frequencies from 14-58 Hz, with a peak at 33.2 Hz (gamma band). The 3D reconstruction showed that these statistical differences were localized in the lateral and posterior regions of the left hemisphere. No significant differences were found between unknown women vs. basal conditions. These results demonstrate recognition of the mother's voice and indicate high-level residual linguistic processing in a patient meeting clinical criteria for VS. These findings launch new ethical and practical implications for the management of VS patients.

[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.

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.

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.

In vitro effect of lung surfactant on alveolar macrophage defence mechanisms against Cryptococcus neoformans

The effects of a modified natural porcine surfactant (Curosurf) on phagocytosis and killing of Cryptococcus neoformans by alveolar macrophages and on the production of superoxide anions were investigated in vitro. Attachment and ingestion were evaluated separately by a fluorescent quenching technique. The nitroblue tetrazolium reduction test was used as an indirect measurement of superoxide anion production. Killing was assessed by a colony-forming assay. Surfactant induced increased ingestion of C. neoformans, unopsonized as well as opsonized with fresh serum or anticryptococcal polyclonal IgG. Surfactant had, however, no effect on the attachment or killing of unopsonized or opsonized C. neoformans by the alveolar macrophages. In addition, the enhancement of the oxidative metabolism of the macrophages after stimulation with opsonized yeast was impaired, although the killing was not affected. This study indicates that in vitro Curosurf can influence the alveolar macrophage defence against C. neoformans by enhancing its ingestion and by interacting with the superoxide anions release from alveolar macrophages stimulated with fresh serum or anticryptococcal polyclonal IgG opsonized yeast cells.

[Eimeria species (Eucoccidida: Eimeriidae) found in the cotton rat Sigmodon hispidus in Costa Rica]

Cotton rats (Sigmodon hispidus) were collected from Ojo de Agua, Alajuela (N = 74) and Cañas, Guanacaste (N = 29). Feces had 31 E. sigmodontis, nine E. tuskegeensis, eight E. roperi, three E. webbae and two Eimeria sp. This is the first report of these coccidian parasites for Costa Rica.

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.

[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.

Interaction between Cryptococcus neoformans and alveolar macrophages

Phagocytosis, oxidative metabolism and phagolysosomal pH of rat alveolar macrophages (AM) were studied at different points of time after challenge with Cryptococcus neoformans. Phagocytosis was evaluated using a fluorescent quenching technique which distinguishes between attached and ingested organisms. The nitroblue tetrazolium (NBT) test was used as an indirect measurement of the oxidative metabolism of the phagocytes. The pH of the phagolysosomes was measured using a cytofluorometric technique. Both the attachment and ingestion of serum opsonized C. neoformans by AM were slow during the first hours of incubation, but were considerable after 24 h. The oxidative metabolism of Am challenged with the yeast was insignificant during the first hour, but reached high levels after 24 h. Most phagolysosomes in AM with ingested cryptococci had a pH < 5.5. Our results indicate that these AM defence mechanisms, although poor during the first hours after exposure to the yeast, are of significance after 24 h. Thus, in the immunocompetent host the AM should prevent the dissemination of C. neoformans from the lungs.

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.

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.

[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.

[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.

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.

[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.

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.

Age influence in the natural resistance of white rat and mice to the protozoan Toxoplasma gondii

Groups of 1, 5, 10, 15 and 30 day old rats (Sprague Dawley) and Wistar mice were infected per os with different inocula of Toxoplasma gondii oocysts from an avirulent strain. Infection pattern was followed by determination of survival time, tissue lesions, parasite presence and serology. Although all the animals survived the total experimental period (30 day), there were important differences between both rodents regarding to Toxoplasma natural resistance. Brain cysts, as well as tachyzoites in other organs were regularly present in mice but not in rats. On the other hand, most of the organs from mice presented characteristic T. gondii lesions, while in rats a normal tissues were observed, with the exception of an acute reaction found in the brain of a 15d old animal.

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.

Seroepidemiology of Toxoplasma gondii (Apicomplexa) in meat producing animals in Costa Rica

A serologic screening for Toxoplasma gondii antibodies by IgG indirect fluorescent antibodies test (IgG-IFAT) was carried among 496 swine and 601 cattle serum samples from throughout Costa Rica, to study the possible role of their meat in the transmission of the parasite. The overall prevalence of antibodies was 34.4% in cattle and 43.8% in swine. No significant differences were found in the antibody prevalence between males and females in both animal groups, which acquire the infection early in their lives. Swine did not present significant differences between age groups. In cattle there was a high percent of seropositivity between the first and third years of age. The provinces that showed a greater number of seropositive animals were Limón and Puntarenas for both animals, and Guanacaste for cattle.

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.

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.

[Effect of corticosteroids on the congenital transmission of experimental toxoplasmosis]

Female white mice with chronic toxoplasmosis were treated with cortisone acetate (3mg for each 25 g of body weight) 12, 8, 4 and 0 days before mating. Cortisone induces congenital transmission of T. gondii.

[Antibodies against Toxoplasma gondii in swine in Costa Rica: epidemiologic importance]

On a three hundred swine sera sample collected from a Municipal Slaughter house and a Research Laboratory at the Ministerio de Agricultura y Ganadería a 26% of positivity against T. gondii was found using the carbon immunoassay. A relationship between the age and swine race are made. The epidemiological significance of this findings are discussed focused mainly on the role of swine meat as a source of human infection in Costa Rica.

Increase of sulfadiazine effect against Toxoplasma gondii by using watermelon or cantaloupe seeds

In an experimental model the anti--Toxoplasma effect of watermelon and cantaloupe seeds, together with sulfadiazine (Sd7.5 and Sd15) given by oral route, were studied. Combination of any of these seeds with the drug was able to increase the survival time and cure some tachyzoite infected mice. The effect was produced either by peeled or complete seeds and more significant results were obtained when Sd7.5 and 10(3) tachyzoite inoculum was used in the model. Some Toxoplasma oocyst infected mice were cured with the seeds alone (75% for watermelon, 37,5 or 50% for cantaloupe. Body weight variations are independent of the treatment with Sd alone or in combination with watermelon or cantaloupe seeds.

Development and distribution of cysts of an avirulent strain of Toxoplasma and the humoral immune response in mice

An avirulent T. gondii strain isolated from a owl (Glaucidium brasilianum) produces randomly distributed cysts in the brain of mice which can survive to inocula as high as 1000 oocysts. Cysts appeared for the first time after 15 days of infection. Regarding to humoral immunity development due to our TCR-2 strain, detectable antibodies were found after 12 days of infection.

[The presence of cysts in Tritrichomonas muris]

Cysts of Tritrichomonas muris are reported. The morphology of this evolution stage is described under light and electron microscopy. The biologic and epidemiologic importance of this finding is discussed.

Growth inhibition of Trypanosoma cruzi in cultured murine myocardial cells mediated by a specifically induced lymphokine

An in vitro model for studying the protection of mouse myocardial cells against Trypanosoma cruzi was developed. It was demonstrated that immune mouse lymphocytes stimulated with a specific antigen elicited a mediator which protected myocardial cells from newborn mice against T. cruzi infection. The substance responsible for this activity was sensitive to acid (pH 2) treatment.

Rat macrophage activity against Toxoplasma gondii studied by electron microscopy

An electron microscope model was used to study the effect of rat peritoneal macrophages on Toxoplasma gondii. 10(7) tachyzoites were injected i.p. in 30 days-old rats. After 1, 2, 4, 8 and 24 h peritoneal exudate was withdrawn and infected phagocytic cells were prepared for electronic microscope studies. Toxoplasma organisms inside of rat macrophages showed remarkable lesions such as vacuolization and organisms were totally lysed inside of macrophages of more than 8 h infection rats. The results confirm at molecular level, the importance of rat macrophages in the natural adaptation of this rodent to T. gondii.

Specific mediation of cellular immunity to Toxoplasma gondii in somatic cells of mice

Lymphocytes from mice immunized against Toxoplasma gondii protected T. gondii-infected macrophage and kidney cell cultures. After contact with antigens, supernatants of such immune lymphocytes, also contained a factor protective for T. gondii-infected macrophages and kidney cells. Supernatants were protective only when the lymphocytes and kidneys cells were isogeneic. Protection was specific in that supernatants from only T. gondii-immune, but not Besnoitia jellisoni-immune, lymphocytes provided protection against toxoplasmosis. Sixteen to 24 h were required for an appreciable amount of protective factor to be secreted; a similar absorption time was necessary for kidney cells to be protected. Peritoneal lymphocyte lysates, prepared as transfer factor, contained protective substances with a potency similar to that of lymphocyte supernatants, which were also strain restricted in their effect.

[Natural adaptation of the white rat to Toxoplasma gondii]

White rats were found to be resistant to 3 x 10(7) Toxoplasma gondii organisms (RH strain) inoculated either sc or ip. That resistance was age-dependent since survival time of 1- or 5-day-old rats inoculated with 10(4) or 10(6) tachyzoites was lower as compared with those 10 or 15 days old. Organisms kept in contact with a lysate of white rat complete peritoneal exudate showed reduced capacity to infect mice. Peritoneal exudate of 5-day-old rats showed a stronger effect than that of 1, 2, 3, or 4 day-infected animals. After 10 days the anti-toxoplasma effect diminished and it almost disappeared after 15 days of infection. Apparently age and macrophage activity are very important factors in the natural adaptability of the white rat to Toxoplasma gondii.

[Effect of corticosteroids in mucocutaneous leishmaniasis. Experimental study]

Groups of "immunized" and "non-immunized" hamsters were inoculated weekly with 2, 10 or 20 mg of cortisone acetate per 100 gr of body weight and infected with Leishmania mexicana or L. braziliensis. Doses of 10 and 20 mg of cortisone were excessive, since the animals died with bacterial infections before they developed leishmaniasis. Inflammation and necrosis were more evident in animals inoculated with cortisone and L. mexicana. Furthermore, this strain caused lesions in lymphatic ganglia of immunosuppressed animals, but was not observed in those inoculated with L. braziliensis. There was no difference between the pathological findings in nonimmune and immune hamsters. These results could indicate that passive immunization with dead antigen is not effective.

[Epidemiology of toxoplasmosis in Costa Rica: the importance of domestic rodents]

A positive dye test for Toxoplasma antibodies was observed in 5% of 100 mice (Mus musculus) and 30.4% of 23 rats (Rattus norvegicus and R. rattus). The parasite was isolated from two mice. The animals were captured in several urban localities in the metropolitan area of San José, Costa Rica. The number of positive animals found appears to be enough to infect cats, whose principal source of infections are the Toxoplasma cysts in the rodents. Therefore it is apparent that domestic mice and rats, besides the felines play an important role in the epidemiology of Toxoplasmosis in Costa Rica. Additional studies showed that the presence of Eimeria falciformis, a common coccidian in domestic mice, did not inhibit the Toxoplasma infections in these rodents.

Mediation of immunity to intracellular infection (Toxoplasma and Besnoitia) within somatic cells

Antigen-treated lymphocytes from immune hamsters specifically protected not only macrophages, but also cultured fibroblasts and kidney cells infected with Toxoplasma gondii or Besnoitia jellisoni. Macrophages were not necessary for the protection of fibroblasts and kidney cells. A mediator that inhibited the intracellular proliferation of these microbes was obtained from immune lymphocytes in contact with specific antigen. Again, macrophages were not necessary for the elaboration of this mediator or its activity in kidney cells or fibroblasts. The mediator was microbe and host specific, had a molecular weight between 4,000 and 5,000, was resistant to heating at 56 degrees C for 30 min, and was sensitive to chymotrypsin, but resistant to ribonuclease and deoxyribonuclease. A single injection of Besnoitia mediator afforded better protection to hamsters infected with Besnoitia than did antibody. Whereas antibody lysed extracellular organisms, the microbe-specific mediators conferred immunity not only on macrophages, but also on other cells of the body, apparently the first such demonstration.

Soil survival of toxoplasma oocysts in Kansas and Costa Rica

Toxoplasma oocysts in cat feces were marked with a tracer amount of strontium-85 (85-SR), and were superficially buried simulating the natural disposal of feces by cats. Oocyst infectivity in Costa Rica was followed qualitatively and persisted for 1 year in three shaded sites, two moist, and one relatively dry site. Oocyst infectivity was quantitated in the Kansas deposit over a period of 18 months, including two winters. After initial mixing in soil, the level of infectivity remained fairly stable. Infectivity was recovered, probably from the surface on one Musca, several isopods, and earthworms. These data on persistence of Toxoplasma oocysts in soil support the concept that Toxoplasma infectivity in nature may be increased logarithmically by cats.