IgG Antibody responses in mice coinfected with Toxocara canis and other helminths or protozoan parasites

The immune response expressed by IgG antibodies in BALB/c mice experimentally infected with Toxocara canis, was studied with the aim of verifying the possible in vivo cross-reactivity between antigens of T. canis and other parasites (Ascaris suum, Taenia crassiceps, Schistosoma mansoni, Strongyloides venezuelensis and Toxoplasma gondii). Experiments included three groups of mice: one infected only by T. canis, another with one of the other species of parasites and a third concomitantly infected with T. canis and the other species in question. Animals were bled by orbital plexus at 23, 38 and 70 days post infection (p.i.). Sera were analyzed for anti-Toxocara antibodies by ELISA and Immunoblotting, using excretion-secretion antigens (ES), obtained from culture of third-stage larvae of T. canis. For all experiments a control group comprised by ten non-infected mice was used. Only in the case of A. suum infection, in these experimental conditions, the occurrence of cross-reactivity with T. canis was observed. However, in the case of co-infection of T. canis - S. mansoni, T. canis - S. venezuelensis and T. canis - T. crassiceps the production of anti-Toxocara antibodies was found at levels significantly lower than those found in mice infected with T. canis only. Co-infection with S. mansoni or S. venezuelensis showed lower mortality rates compared to what occurred in the animals with single infections. Results obtained in mice infected with T. canis and T. gondii showed significant differences between the mean levels of the optical densities of animals infected with T. canis and concomitantly infected with the protozoan only in the 23rd day p.i.

The infectivity of single flagellates of Trypanosoma cruzi

Single organisms of Trypanosoma cruzi of the virulent Peru strain were isolated by direct visualisation and were injected peritoneally into CFI mice. Single trypanomastigotes of different morphology and from different sources (mouse blood, in vitro cufture and bug faeces) were used. Single trypanomastigotes from mouse blood caused parasitaemia and fataiity in a high percentage of mice. This was true irrespective of the morphology (broad or narrow form) of the trypano mastigo tec. Single organisms of the culture forms were also capable of causing infection, although these were less infectious than single trypanomastigotes obtained from mouse blood or the reduviid bug. The difficulties attendant on the performance of the cloning technique are discussed and some indication is given of how these problems can be overcome.

Kinetics of the cercaria-schistosomulum transformation in vivo

Sitice most studies on the cercaria-schistosomulum transformation have been carried out in vitro, the authors used the inoculation ofcercariae into the peritoneal cavity of mice tofollow the steps involved in this progressive adaptation of cercarie to the vertebmte host. The main conclusions were: 1. Most cercariae reach the schistosomular stage between 90-120 min after intraperitoneal inoculation. 2. Changes usuallystart with detachment of the tail followed by loss, rupture or changes of the glycocalix. 3. After 120 min most larvae loss their tails and present water sensitivity. 4. Acetabular grands depletion usually does not occur in cercaria-shistosomulum changes in the peritoneal cavity of mice. These steps differ in some way from those described in the kinetics of the in vitro observations performed by other investigators, and is more like those described in the penetration in the skin of living vertebrates.

Experimental paracoccidioidomycosis in the mouse. III. Histopathological and immunological findings after intravenous infection in the presence or absence of previous immunization

Fifty male white Swiss mice aged 4 weeks were inoculated with 5 x 10(5) viable yeast forms of Paracoccidioides brasiliensis (strain 18). Ten of these animals had been previously immunized with particulate P. brasiliensis antigenfor 4 weeks by intradermal injection. The controls consisted of 10 animals that were only immunized and 10 animals submitted to no treatment. The animals were sacrificed 2, 4, 7,11 and 16 weeks later. We studied: 1) the anti-P. brasiliensis delayed hypersensitivity response measured by the footpad test 24 hours prior to sacrifice; 2) the specific antibody production measured by double immunodiffusion in agar gel; 3) the histopathology of lungs, liver, spleen, adrenals and kidneys. We observed that: a) the immunized animals developed more intense cell-immune responses than the infected ones; b) infection reduced the cell- immune response of the immunized animals; c) intravenous infection of mice with P. brasiliensis was characterized by a systemic and progressive granulomatous inflammation. The animals infected after previous immunization showed less extensive lung inflammation, with smaller granulomas and fewer fungi. The results indicate that the present murine model mimics some findings of the human subacute form of paracoccidioidomycosis (systemic disease with depressed cellular immunity) and that the extrapulmonary immunization scheme was able to induce a certain degree of protection of the lung from infection with P. brasiliensis

Kinetics of the cercaria-schistosomul um transformation in vivo: 2. The effect of oxamniquine

To study the cercaria-schistosomulum transformation in vivo, underthe influence of an antischistosomal compound (oxamniquine), a model using cercarial infections into the abdominal cavity of mice was chosen. This procedure provided easy and reproducible recoveries of larvae from peritoneal washings with appropriate solutions for a long time (30 to 180 min) after inoculation. The results show that high doses of oxamniquine (given intramuscularly one hour before the infection) produce a marked delay in the kinetics of the cercaria-schistosomulum transformation. Cercariae, tail-less cercarial bodies and schistosomula were recovered from the peritoneal cavity ofdrug treated mice in numbers significantly different from those recovered from untreated mice.

Effects of betamethasone on the course of experimentai. Infection with Trypanosoma cruzi

In this experiment, the effect of betamethasone administered in the early post- acute infection of mice by Trypanosoma cruzi was studied. This drug was administered during 30 days after the 42nd day of infection in a dose of 0.15 mg/day. The betamethasone treatment did not cause fresh outbreaks of parasitemia and the histopathological findings in the chronic phase were not different from those in the control group. The higher cumulative mortality after treatment in the experimental group was due to superimposed bacterial infections. Outbred albino mice infected with low numbers ofY strain Trypanosoma cruzi trypomastigotes were not suitable models for Chagas' disease, since after 7 months of observation only mild histological lesions developed in all the animais. Prolonged betamethasone treatment of mice infected with low numbers o/Trypanosoma cruzi of the Y strain, during the post-acute phase did not aggravate the course of infection.

Medium-term cryopreservation of rabies virus samples

Introduction The cryopreservation of rabies virus has been described in detail in the literature. To date, little information is available on the use of cryoprotective agents for cold preservation of this virus, and the available data focus only on short-term virus preservation. In this study, we investigated the medium-term cryopreservation of samples of rabies virus using different cryopreservation protocols. Methods The cryopreservation protocols for the rabies virus samples were performed at -20°C and were divided according to the variables of time and cryoprotectant type used. The laboratory tests (intracerebral inoculation of mice, viral titration and direct immunofluorescence) were performed at regular intervals (360 and 720 days) to assess the viability of the viral samples according to the different preservation techniques used. Results After 1 year of cryopreservation, the fluorescence intensity of intracellular corpuscles of the rabies virus and the median survival time of the mice differed between the positive controls and the treatments with the cryoprotectants. After 2 years, most of the samples subjected to the cryopreservation protocols (including the controls) did not produce fluorescence. However, the virus samples exposed to the cryoprotectant sucrose (68% solution) responded positively in the direct immunofluorescence assay and in the intracerebral inoculation of the mice. Conclusions Medium-term cryopreservation of the rabies virus inactivates the viral sample. However, the cryoprotectant agent sucrose (68%) produces a preservative effect in cryopreserved rabies virus samples.

Detection of intestinal parasites on field-grown strawberries in the Federal District of Brazil

Introduction This study evaluated the presence of pathogenic human parasites on field-grown strawberries in the Federal District of Brazil. Methods A total of 48 samples of strawberries and 48 soil samples from 16 properties were analyzed. Results Contaminated strawberries were detected in 56% of the properties. Schistosoma mansoni, Ascaris lumbricoides or Ascaris suum, Balantidium coli, Endolimax nana, and Entamoeba spp. were detected. Soil was contaminated with Entamoeba spp., Entamoeba coli, Strongyloides spp., Ancylostomatidae, and Hymenolepis nana. Conclusions Producers should be instructed on the safe handling of strawberries in order to reduce the incidence of strawberries that are contaminated with enteroparasites.

Cost of drugs manufactured by the University Hospital - role of the Central Pharmacy

The hospital pharmacy in large and advanced institutions has evolved from a simple storage and distribution unit into a highly specialized manipulation and dispensation center, responsible for the handling of hundreds of clinical requests, many of them unique and not obtainable from commercial companies. It was therefore quite natural that in many environments, a manufacturing service was gradually established, to cater to both conventional and extraordinary demands of the medical staff. That was the case of Hospital das Clinicas, where multiple categories of drugs are routinely produced inside the pharmacy. However, cost-containment imperatives dictate that such activities be reassessed in the light of their efficiency and essentiality. METHODS: In a prospective study, the output of the Manufacturing Service of the Central Pharmacy during a 12-month period was documented and classified into three types. Group I comprised drugs similar to commercially distributed products, Group II included exclusive formulations for routine consumption, and Group III dealt with special demands related to clinical investigations. RESULTS: Findings for the three categories indicated that these groups represented 34.4%, 45.3%, and 20.3% of total manufacture orders, respectively. Costs of production were assessed and compared with market prices for Group 1 preparations, indicating savings of 63.5%. When applied to the other groups, for which direct equivalent in market value did not exist, these results would suggest total yearly savings of over 5 100 000 US dollars. Even considering that these calculations leave out many components of cost, notably those concerning marketing and distribution, it might still be concluded that at least part of the savings achieved were real. CONCLUSIONS: The observed savings, allied with the convenience and reliability with which the Central Pharmacy performed its obligations, support the contention that internal manufacture of pharmaceutical formulations was a cost-effective alternative in the described setting.

Predation of bat (Molossus molossus: Molossidae) by the centipede Scolopendra viridicornis (Scolopendridae) in Southern Amazonia

Centipedes are opportunistic carnivore predators, and large species can feed on a wide variety of vertebrates, including bats. The aim of this study was to report the third record of bat predation by centipedes worldwide, the first record in the Amazon region, while covering aspects of foraging, capture and handling of prey. We observed the occurence in a fortuitous encounter at Cristalino State Park, located in the Amazon region of the state of Mato Grosso, Brazil. The attack took place in a small wooden structure, at about three meters from the floor, and was observed for 20 minutes. During the observation, the centipede stung the neck and abdominal region of the bat several times, grabbing the prey with its 15 pairs of front legs while hanging from the ceiling with its hind legs. This type of observation suggests that vertebrates can be important preys for invertebrates such as giant centipedes, both for its nutritional composition and for the amount of energy available in a single prey.

Shape and size variations of Aegla uruguayana (Anomura, Aeglidae) under laboratory conditions: A geometric morphometric approach to the growth

Crustacean growth studies typically use modal analysis rather than focusing on the growth of individuals. In the present work, we use geometric morphometrics to determine how organism shape and size varies during the life of the freshwater crab, Aegla uruguayana Schmitt, 1942. A total of 66 individuals from diverse life cycle stages were examined daily and each exuvia was recorded. Digital images of the dorsal region of the cephalothorax were obtained for each exuvia and were subsequently used to record landmark configurations. Moult increment and intermoult period were estimated for each crab. Differences in shape between crabs of different sizes (allometry) and sexes (sexual dimorphism; SD) were observed. Allometry was registered among specimens; however, SD was not statistically significant between crabs of a given size. The intermoult period increased as size increased, but the moult frequency was similar between the sexes. Regarding ontogeny, juveniles had short and blunt rostrum, robust forehead region, and narrow cephalothorax. Unlike juveniles crabs, adults presented a well-defined anterior and posterior cephalothorax region. The rostrum was long and stylised and the forehead narrow. Geometric morphometric methods were highly effective for the analysis of aeglid-individual- growth and avoided excessive handling of individuals through exuvia analysis.

Differential effect of culture epimastigotes and blood-form Trypamastigotes on normal mouse splenocyte responsiveness to mitogens

Blood form trypomastigotes of the Y strain of T. cruzi, produced a strong inhibition of the blastogenic response to T and B cell mitogens, of the C3H/He, C57BLand BALB/cJ strains of mice, while culture epimastigotes of the Y strain kept in a medium that allows parasite growth at 26°. 30° and 37°C produced a strong stimulatory effect that was even higher than the effect of the mitogens alone. Both the inhibitory or the stimulatory effects were dose-dependent. The stimulatory effect of epimastigotes was also temperature-dependent producing increasedstimulation indexes as the temperature of parasite cultures was raised. Metabolically active,living parasites seemed to be necessary for an improved lymphocyte stimulation suggesting a potential role of secreted metabolites as polyclonal activators of mouse lymphocytes.

A contribution to the study of acute schistosomiasis (an experimental trial)

In an attempt to establish an experimental model of acute schistosomiasis, sequential histological changes were investigated in the skin, lung, liver and spleen of mice infected with 30 or 100 cercariae of Schistosoma mansoni according to four sets of experiments: single infection, repeated infections, unisexual infection and infection in mice born from infected mothers. Animals were killed every other day from exposure up to 50 days after infection. Only mild, isolated, focal inflammatory changes were found before the appearance of mature eggs in the liver, even when repeated infections were made. Severe changes of reactive hepatitis and splenitis appeared suddenly when the first mature eggs were deposited, around the 37th to 42nd day after infection. The mature eggs induced lytic and coagulative necrosis of hepatocytes around them which was soon followed by dense infiltration of eosinophils. So, mature egg-induced lesions appeared as the major factors in the pathogenesis of acute schistosomiasis in mice. Mice born from infected mothers were apparently able to rapidly modulate the egg-lesions, forming early fibrotic granulomas. The murine model of acute schistosomiasis appeared adequate for the study of pathology and pathogenesis of acute schistosomiasis.

The use of monoclonal antibodies for the characterization and production of Mycobacterium leprae antigens

Similar immunizations of mice and hybridoma technology were used by several investigators to raise monoclonal antibodies which identified a limited range of epitopes and antigenic molecules. Further studies would have the scope for revealing yet more novel structures. The existing MABs are agreed standard reagents, avaiable to investigators and valuable for several applications. At least six epitopes specific for M. leprae were defined in molecular terms. Monoclonal antibody based immunoassays proved to be invaluable for the screening of recombinant DNA clones and for the topographic study of individual epitopes. Purification of antigens using affinity chromatography requires further development of techniques whilst serology of leprosy is open for clinical and epidemiological evaluation.

Evaluation of Chagas' disease transmission through breast-feeding

On hundred milk or colostrum samples from 78 mothers with chronic Chagas' disease were parasitologically studied for Trypanosoma cruzi infection by means of direct examination and inoculation of mice. The mice were submitted to direct bllod examination three times a week. At the end of 45 days, xenodiagnosis and indirect immunofluorescent test (IFAT) for T. cruzi antibodies were carried out in the animals. No parasitized sample was observed even though five mothers had parasitemia at milk collection. In addition, 97 breast-fed children of chronic chagasic mothers, born free of infection, were tested for IgG antibodies to T. cruzi using IFAT. No case of T. cruzi infection was detected. The authors conclude that breast-feeding should not be avoided for children for chronic chagasic women. However, as these mothers had intermittent parasitemia, they should avoid nursing when there is nipple bleeding.