Effect of oxamniquine on cell adhesion to Schistosoma mansoni larvae in the peritoneal cavity of naive mice

The treatment of naive mice with high closes of oxamniquine, 1 hour before the intraperitoneal inoculation of Schistosoma mansoni cercariae, induces a delay in the transformation process resulting in a longer host cell adhesion.

A low-cost method to test cytotoxic effects of Crotalus vegrandis (Serpentes: Viperidae) venom on kidney cell cultures

The pathogenesis of the renal lesion upon envenomation by snakebite has been related to myolysis, hemolysis, hypotension and/or direct venom nephrotoxicity caused by the venom. Both primary and continuous cell culture systems provide an in vitro alternative for quantitative evaluation of the toxicity of snake venoms. Crude Crotalus vegrandis venom was fractionated by molecular exclusion chromatography. The toxicity of C. vegrandis crude venom, hemorrhagic, and neurotoxic fractions were evaluated on mouse primary renal cells and a continuous cell line of Vero cells maintained in vitro. Cells were isolated from murine renal cortex and were grown in 96 well plates with Dulbecco's Modified Essential Medium (DMEM) and challenged with crude and venom fractions. The murine renal cortex cells exhibited epithelial morphology and the majority showed smooth muscle actin determined by immune-staining. The cytotoxicity was evaluated by the tetrazolium colorimetric method. Cell viability was less for crude venom, followed by the hemorrhagic and neurotoxic fractions with a CT50 of 4.93, 18.41 and 50.22 µg/mL, respectively. The Vero cell cultures seemed to be more sensitive with a CT50 of 2.9 and 1.4 µg/mL for crude venom and the hemorrhagic peak, respectively. The results of this study show the potential of using cell culture system to evaluate venom toxicity.

Decline in prevalence and asymmetric distribution of human T cell lymphotropic virus 1 and 2 in blood donors, State of Minas Gerais, Brazil, 1993 to 2007

INTRODUCTION: Human T cell lymphotropic virus types 1 and 2 (HTLV-1/2) are endemic in Brazil and are screened for in transfusion services since 1993. This study evaluated the evolution of the prevalence of HTLV-1 and 2 in blood donors of the Hemominas Foundation from 1993 to 2007, and its geographical distribution in State of Minas Gerais, Brazil. METHODS: The Hemominas Foundation is a centralized blood center in Minas Gerais, Brazil. The sources of data were the Hemominas Foundation Technical Bulletin and files from the centralized serological laboratory. Donors were tested in the period using enzyme linked immuno sorbent assays (ELISA), followed by Western blot, when repeatedly reactive. The data were analyzed by EPIINFO 6.2 and TABWIN 3.5 softwares. RESULTS: The average seroprevalence in the period 1993-2007 was 0.1%. A steady decline occurred from 0.4% in 1993 to below 0.1% in 2002 and later, with a transient peak of 0.5% in 1994. HTLV reactivity distribution was asymmetrical in the state, with regions of higher prevalence, interspersed with low prevalence areas. Comparison of positive and negative donors verified that increasing age was proportional to virus positivity. Odds ratio for age ranged from 1.43 (30 to 39 years-old) to 3.09 (50 to 65 years-old). Women had a greater chance of being positive (OR-1.64), as previously described. CONCLUSIONS: Possible explanations for HTLV-1/2 prevalence decline are the exclusion of positive donors from the donor pool, an increase in repeat donors and ELISA test improvement, with reduction in the number of false positive results.

Chemotherapy versus best supportive care in stage IV non-small cell lung cancer, non metastatic to the brain

Stage IV non-small cell lung cancer is a fatal disease, with a median survival of 14 months. Systemic chemotherapy is the most common approach. However the impact in overall survival and quality of life still a controversy. OBJECTIVES: To determine differences in overall survival and quality of life among patients with stage IV non-small cell lung cancer non-metastatic to the brain treated with best supportive care versus systemic chemotherapy. PATIENTS: From February 1990 through December 1995, 78 eligible patients were admitted with the diagnosis of stage IV non-small cell lung cancer . Patients were divided in 2 groups: Group A (n=31 -- treated with best supportive care ), and Group B (n=47 -- treated with systemic chemotherapy). RESULTS: The median survival time was 23 weeks (range 5 -- 153 weeks) in Group A and 55 weeks (range 7.4 -- 213 weeks) in Group B (p=0.0018). In both groups, the incidence of admission for IV antibiotics and need of blood transfusions were similar. Patients receiving systemic chemotherapy were also stratified into those receiving mytomycin, vinblastin, and cisplatinum, n=25 and those receiving other combination regimens (platinum derivatives associated with other drugs, n=22). Patients receiving mytomycin, vinblastin, and cisplatinum, n=25 had a higher incidence of febrile neutropenia and had their cycles delayed for longer periods of time than the other group. These patients also had a shorter median survival time (51 versus 66 weeks, p=0.005). CONCLUSION: In patients with stage IV non-small cell lung cancer, non-metastatic to the brain, chemotherapy significantly increases survival compared with best supportive care.

The relation of the concentration of macronutrients in the substrate and in the foliage to cell wall thickness and cellulose concentration in the xylem of slash pine (Pinus elliotti)

Sand culture experiments, using a sub-irrigation technique, were installed in order to find out the effects of the macronutrients N, P, K, Ca, Mg and S on growth, aspect, mineral composition, length of fibers, thickness of cell wall and cellulose concentration in slash pine. The aim was to obtain, under controlled conditions, basic information which could eventually lead to practical means designed to increase the rate of growth and to make of slash pine a richer source of cellulose. Nitrogen, Phosphorus, Potassium Experiment A 3 x 3 x 3 factorial design with two replicates was used. Nitrogen was supplied initially at the levels of 25, 50 and 100 ppm; phosphorus was given at the rates of 5, 10 and 20 ppm; potassium was supplied at the rates of 25, 50 and 100 ppm; six months after the experiment was started the first level for each element was dropped to zero. Others macro and all micronutrients were supplied at uniform rates. Fifteen hours of illumination per day were provided. The experimental technique for growing the slash pine seedlings proved quite satisfactory. Symptoms of deficiency of nitrogen, phosphorus and potassium were observed, described and recorded in photographs and water colors. These informations will help to identify abnormalities which may appear under field conditions. Chemical analysis of the several plant parts, on the other hand, give a valuable means to assess the nutritional status of slash pine, thus confirming when needed, the visual diagnosis. The correctness of manurial pratices, on the other hand, can be judged with the help of the analytical data tabulated. Under the experimental conditions nitrogen caused the highest increases on growth, as measured by increments in height and dry weights, whereas the effects of phosphorus and potassium were less marked. Cellulose concentration was not significantly affected by the treatments used. Higher levels of N seemed to decrease both length of fiber elements and the thickness of cell wall. The effects of P and K were not well defined. Calcium, Magnesium, Sulfur Experiment A 3 x 3 x 3 factorial design with two replicates was used. Calcium was supplied initially at the levels of 12.5, 25 and 50 ppm; magnesium and sulfur were given at the rates of 6, 12.5 and 25 ppm. Other macro and micronutrients were supplied at uniform rates, common to all treatments. Three months after starting the experiment the first level for each element was dropped to zero. Symptoms of deficiency of calcium, magnesium and sulfur were observed, described and recorded as in the case of the previous experiment. Chemical analysis were made, both for mineral content and cellulose concentration. Length of fibers and thickness of cell wall were measured. Both calcium and magnesium increase height, sulfur failing to give significant response. Dry weight was beneficially affected by calcium and sulfur. The levels of calcium, magnesium and sulfur in the needles associated with deficiency and maximum growth are comparable with those found in the literature. Cellulose concentration increased when the level of sulfur in the substrate was raised. The thickness of cell wall was negatively affected by the treatments; no effect was observed with regards to length of fibers.

Development of cell mediated immunity to flagellar antigens and acquired resistance to infection by Trypanosoma cruzi in mice

Modulation by BCG and/or cyclophosphamide of sensitization of mice with flagellar fraction (a tubulin-enriched fraction) prevented death of mice challenged with T. cruzi CL strain trypomastigotes recovered from Vero cells. A methodology was ceveloped to assay specific antigens and to determine optimal doses for sensitization and elicitation of DTH in mice. CL strain is predominantly myotropic strain which does not produce important parasitism of mononuclear phagocyte cells; these cells appear to control infection when activated in vivo. Maximum protection was seen in this study when BCG and cyclophosphamide were associated, but protection was observed also when cyclophosphamide, that prevents supressor T cells, was applied 2 days before flagellar fraction sensitization in normal mice. These experiments suggested that the macrophage may have an important role in the early phases of infection particularly when nonspecific stimulation is associated with specific sensitization. A correlation betwen delayed hypersensitivity to parasite antigens and protection was observed.

A simple method for assessing the binding of concanavalin A to mononuclear cell surfaces: no interference of visceral leishmaniasis serum on this binding

We report a simple method for evaluating the binding of concanavalin A (ConA) to human peripheral blood mononuclear cells (PBMC). The binding is evidenced by an immunoenzymic assay using peroxidase-conjugated immunoglobulins of a rabbit anti-ConA serum. Using the method we show that sera from patients with American leishmaniasis do not interfere with binding of ConA to PBMC.

Restriction in the repertoire of detectable autoantibodies in polyclonal B cell activations and the mimicry of autoantigens by idiotopes

Despite the existence of erythrocyte-autoreactive B cells in normal animals, erythrocyte-autoantibodies could not be detected during polyclonal B-cell activation (PBA) both in patients with visceral leishmaniasis and in bacterial lipopolysacharide (LPS) - injected mice. The failure to detect these autoantibodies in mice with PBA di not seem to be due to suppressor-cell activity, since (1) transfer of spleen cells from LPS-treated mice to naive recipients did not affect the erythrocyte-autoantibody response elicited by subsequent injections of rat erythrocytes and (2) low doses of X-radiation did no lead to erythrocyte-autoantibody detection in LPS-treated mice. The possibility that the detection of erytrocyte-autoantibodies could be affected by autoantibodies with idiotopes mimicring erythrocyte epitopes, the synthesis of which would also be triggerred in PBA, is discussed. Indirect evidence for the existence in normal animal of an expanded lymphocyte population with DNP-binding. Ia-mimicring antigen receptors is presented.

T-cell response to my mycobacterial antigens in lepromatous and tuberculoid leprosy

We showed that a large fraction of lepromatous patients do harbor helper-type circulating T-cells that can be activated in vitro by Mycobacterium leprae. M. leprae and PPD triggered T-cell lines could be then obtained from both tuberculoid and lepromatous patients. The proliferative response of these helper T-cells is predominantly directed against epitopes shared by several species of mycobacteria, in lepromatous patients as well as in tuberculoid patients, but species specific T-cells are also present. When presented in the context of M. leprae, these cross reactive epitopes usually fail to stimulate the T-cell lines of lepromatous patients, because of the contamination of the lines by supressor T-cells actavable by M. leprae. In one lepromatous patient, PPD and M. leprae reactive T-cell lines and clones (of the CD4 phenotype), exhibited a strong cytotoxic activity to autologous target cells coated with antigen: the relevance of this phenomenon to the pathophysiology of lepromatous leprosy remains however unknown.

T cell responses to repeat and non-repeat regions of the circumsporozoite protein detected in volunteers immunized with Plasmodium falciparum sporozoites

The design of malarial vaccine based on the circumsporozoite (CS) protein, a majuor surface antigen of the sporozoite stage of the malaria parasite, requires the identification of T and B cell epitopes for inclusion in recombinant or synthetic vaccine candidates. We have investigated the specificity and function of a series of T cell clones, derived from volunteers immunized with Plasmodium falciparum sporozoites in an effort to identify relevant epitopes in the immune response to the pre-erythrocytic stages of the parasite. CD4+ T cell clones were obtained wich specifically recognized a repetitive epitope located in the 5'repeat region of the CS protein. This epitope, when conjugated to the 3'repeat region in a synthetic MAPs construct, induced high titers of antisporozoite antibodies in C57B1 mice. A second T cell epitope, which mapped to aa 326-345 of the carboxy terminal, was recognized by lytic, as well as non-lytic, CD4+ T cells derived from the sporozoite-immunized volunteers. The demonstration of CD4+ CTL in the volunteers, and the recent studies inthe rodent model (Renia et al., 1991; Tsuji et al., 1990), suggested that CS-specific CD4+ T cells, in addition to their indirect role as helper cells in the induction of antibody and CD8 + effector cells, may also play a direct role in protection against sporozoite challenge by targeting EEF within the liver.

T cell derived cytokines in lung-phase immunity to Schistosoma mansoni

In C57Bl/6 strain mice vaccinated with radiation-attenuated cercariae of Schistosoma mansoni immune elimination of challenge parasites occurs in the lungs. Leococytes were recovered from the lungs of such mice by bronchoalveolar lavage and cultured in vitro with larval antigen; the profile of cytokines released was then analyzed. From 14 days after vaccination, BAL cultures contained infiltrating lymphocytes wich produced abundant quantitties of IFN-g and IL-3. Challenge of vaccinated mice resulted in a second influx of IFN-g nd IL-3- producing cells, earlier than after vaccination or in the appropriate contropls. Ablation studies revealed that CD4+ T cells were the source of IFN-g. The timing of cytokine production after vaccination, and challenge was coincident with the phases of macrophage activation previously reported. At no time could lymphocytes in BAL cultures to stimulated to proliferate with either larval Ag or mitogen, in contrast to splenocytes from the same mice. Furthermore, T cell growth factor activity was not detected in BAL cultures stimulated with Ag. We suggest that the lymphocytes recruited to the lungs are memory/effector cells, When Ag. released challenge schistosomula is presented to these cells, they respond by secreting cytokines wich mediate the formation of cellular aggregates around the parasites, blocking their onward migration.

Vibrio fluvialis attachs to but does not enter Hela cell monolayers

Considering the possibility that invasiveness could be a neglected factor of virulence in Vibrio fluvialis-linked enteritis, since a dysenteric form of the disease was seen in Bangladesh, we studied 12 Brazilian strains of the organism, six clinical and six environmental, to determine whether they might be able to enter into HeLa cell monolayers or would carry plasmids incidentally involved in invasiveness. Four human and two environmental isolates attached to but did not enter into the cells. Though five strains harbored plasmids,no relationship was found between the carriage of these genetic elements and adhesiveness.

CD4+, CD8+ and CD4- CD8- T cell-subsets can confer protection against Leishmania m. mexicana infection

We studied the role of CD4+, CD8+, CD4- CD8- T cells and IgG anti-Leishmania after infection or vaccination in the CBA/ca mouse. Mice were either infected with L. m. mexicana promastigotes or vaccinated with parasite-membrane antigens incorporated into liposomes. Successfully vaccinated mice were used as cell-donors in adoptive transfer experiments. Naive, syngeneic recipients received highly-enriched CD4+, CD8+ or CD4- CD8- T cells from those two set of donors and challenged with live parasites. Our results showed that, both CD4+ and CD8+ T cells from infected or vaccinated donors conferred significant disease-resistance to naive recipients. In addition, adoptive transfer of CD4- CD8- T cells from vaccinated donors significantly delayed lesion growth in recipient mice. We concluded that vaccination of CBA mice correlates with the induction of protective CD4+, CD8+ and CD4- CD8- T cells and the synthesis of IgG anti-Leishmania.