Percolation on Lieb lattices.

We study site- and bond-percolation on a class of lattices referred to as Lieb lattices. In two dimensions the Lieb lattice (LL) is also known as the decorated square lattice, or as the CuO_{2} lattice; in three dimensions it can be generalized to a layered Lieb lattice or to a perovskite lattice. Emergent electronic phenomena, such as topological states and ferrimagnetism, have been predicted to occur in these systems, which may be realized in optical lattices as well as in solid state. Since the study of the interplay between quantum fluctuations and disorder in these systems requires the availability of accurate estimates of geometrical critical parameters, such as percolation thresholds and correlation length exponents, here we use Monte Carlo simulations to obtain these data for LLs when a site (or bond) is present with probability p. We have found that the thresholds satisfy a mean-field (Bethe lattice) trend, namely that the critical concentration, p_{c}, increases as the average coordination number decreases; our estimates for the correlation length exponent are in line with the expectation that there is no change in the universality class.

Finite-size scaling behavior in trapped systems.

Numerical transfer-matrix methods are applied to two-dimensional Ising spin systems, in the presence of a confining magnetic field which varies with distance |x| to a "trap center," proportionally to (|x|/ℓ)p, where p>0 . On a strip geometry, the competition between the "trap size" ℓ and the strip width L is analyzed in the context of a generalized finite-size scaling ansatz. In the low-field regime ℓ >> L, we use conformal-invariance concepts in conjunction with a linear-response approach to derive the appropriate (p-dependent) limit of the theory, which agrees very well with numerical results for magnetization profiles. For high fields ℓ ≲ L, correlation-length scaling data broadly confirm an existing picture of p-dependent characteristic exponents. Standard spin-1/2 and spin-1 Ising systems are considered, as well as the Blume-Capel model.

Role of trehalose dimycolate in recruitment of cells and modulation of production of cytokines and NO in tuberculosis.

Mice treated with viable Mycobacterium tuberculosis with no glycolipid trehalose dimycolate (TDM) on the outer cell wall (delipidated M. tuberculosis) by intraperitoneal or intratracheal inoculation presented an intense recruitment of polymorphonuclear cells into the peritoneal cavity and an acute inflammatory reaction in the lungs, respectively. In addition, lung lesions were resolved around the 32nd day after intratracheal inoculation. TDM-loaded biodegradable poly-DL-lactide-coglycolide microspheres as well as TDM-coated charcoal particles induced an intense inflammatory reaction. In addition, high levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), IL-12, IL-10, gamma interferon (IFN-gamma), and IL-4 production were detected in lung cells, and nitric oxide (NO) production was high in culture supernatants of bronchoalveolar lavage cells. These in vivo data were confirmed by in vitro experiments using peritoneal macrophages cultured in the presence of TDM adsorbed onto coverslips. High levels of IFN-gamma, IL-6, TNF-alpha, IL-12, IL-10, and NO were detected in the culture supernatants. Our results suggest that TDM contributes to persistence of infection through production of cytokines, which are important for the recruitment of inflammatory cells and maintenance of a granulomatous reaction. In addition, our findings are important for a better understanding of the immunostimulatory activity of TDM and its possible use as an adjuvant in experiments using DNA vaccine or gene therapy against tuberculosis.

Correlation among immune response, morphogenesis of the granulomatous reaction and spleen lymphoid structure in murine experimental paracoccidioidomycosis.

We studied the correlation among cellular immune response, the pattern of lung granulomatous lesions and alterations in spleen lymphoid structure in Swiss mice inoculated intravenously with Paracoccidioides brasiliensis strain 18. The animals were evaluated at 24, 48 and 96 h after infection and further studied weekly for 18 weeks by: (i) the macrophage migration inhibition test with phytohemagglutinin (PHA) and P. brasiliensis antigen (PbAg); and (ii) histopathology of the lung and spleen lesions. One group of animals was gamma-irradiated (8 Gy), infected under the same conditions and evaluated for the pattern of lung granulomatous lesions and spleen lymphoid structure at 24, 48 and 96 h after infection. During the first week of infection, the non-irradiated animals presented a positive response to PHA and PbAg, compact granulomas in the lungs and a typical hyperplasia of the spleen white pulp. However, from weeks 2 to 5, a depression of the cell-mediated immunity (CMI) response to PHA and PbAg was observed in association with granulomas presenting only large mononuclear cells and lacking both giant cells and a peripheral halo of small mononuclear cells. This pattern of granuloma formation was similar to that seen in gamma-irradiated animals, whose cells involved in CMI were absent. After week 7, the non-irradiated animals showed granulomas characterized by the presence of giant cells and a peripheral halo of small mononuclear cells. This type of granuloma was formed concomitantly with recovery of the CMI and of the lymphoid structure of the spleen. The results showed a correlation among granulomas composed of large mononuclear cells, hypoplasia of the splenic tissue and impaired CMI. This correlation indicated that although granuloma morphogenesis per se does not depend on the activation of CMI, this response is important at later stages during modulation of the cellular composition of the granulomas.

[Reactivation of Trypanosoma cruzi infection in patients with acquired immunodeficiency syndrome]. / Reativação da infecção por Trypanosoma cruzi em paciente com síndrome de imunodeficiência adquirida.

A patient with AIDS and asymptomatic Chagas's disease and positive xenodiagnosis was taking ketoconazole in order to suppress parasitemia and prevent reactivation of Chagas's disease. Ketoconazole was unplanned suspended after 6 months, and the patient was admitted with fever, headache, vomiting, tachycardia, postural hypotension, hepatosplenomegaly, and positive xenodiagnosis one month later. Treatment with benzonidazole was begun leading to suppression of parasitemia. The patient had probability a neurotoxoplasmosis associated and progressed to coma and death with sepsis. No parasite was found in autopsy.

A support system for content-based medical image retrieval in object oriented databases.

This work describes both the concepts used in an Object Manager for storage of medical images as one more data type associated to objects, and a support system developed to offer this kind of tool to medical application developers. The purpose of this work is to support the retrieval of images through queries based on the graphical contents of the stored images. The usual approach uses icons and textual attributes stored with the images to specify the queries. This work uses a novel modeling technique to define the "image data type," by means of which it is possible to decide, before the query itself, the key data of each image that must be extracted from the image when it is stored in the database, so the search can be accelerated when queries are issued. This approach enables building of expansible systems, where new image processing algorithms can be added easily, using its syntactic representation stored through an Image Meta-schema into the application database schema. This work shows how such a system has been implemented, and also provides a query language used to refer and execute these algorithms from inside the database management system.

Requirement for lymphocytes and resident macrophages in LPS-induced pleural eosinophil accumulation.

In this study we investigated the involvement of inflammatory cells in the pleural accumulation of eosinophils induced by lipopolysaccharide (LPS). Intrathoracic (i.t.) injection of LPS (250 ng/cavity) into rats induced a significant eosinophil accumulation that developed within 24 h, was maximal at 48 h, and returned to control values within 120 h. This eosinophil influx was preceded by a huge neutrophil influx within 4 h and accompanied by a mononuclear cell accumulation between 24 and 48 h. Pretreatment with an antineutrophil monoclonal antibody (RP-3, 2 ml per animal) selectively reduced the number of circulating neutrophils within 8 h but failed to alter the LPS-induced eosinophilia. Similarly, platelet depletion with an anti-rat platelet antiserum did not alter the LPS-induced eosinophil accumulation. Cyclosporine (50 mg/kg, 12 and 2 h before) partially inhibited (51%) the LPS-induced pleural eosinophilia, whereas the eosinophilia was not changed by prior degranulation of pleural mast cells with polymyxin B (10 micrograms/cavity, 24 h before). Moreover, selective depletion of T lymphocytes using an anti-Thy 1.0 monoclonal antibody significantly inhibited the eosinophilia triggered by LPS. The i.t. injection of liposomes containing dichloromethylene diphosphonate significantly reduced (65%) the number of resident macrophages after 5 days. Under this condition, the eosinophil infiltration induced by LPS was completely inhibited. Accordingly, the i.t. injection of supernatant from macrophage monolayers, obtained from the pleural cavities of LPS-injected rats, into naive recipient animals led to a twofold increase in the number of pleural eosinophils. In conclusion, our data suggest an important role for resident macrophages and T lymphocytes in the eosinophil accumulation induced by LPS.

Anti-CD4 abrogates rejection and reestablishes long-term tolerance to syngeneic newborn hearts grafted in mice chronically infected with Trypanosoma cruzi.

The contribution of autoimmunity in the genesis of chronic Chagas' heart pathology is not clear. In the present study, we show that: (a) BALB/c mice chronically infected with Trypanosoma cruzi reject syngeneic newborn hearts; (b) in vivo treatment with anti-CD4 but not anti-CD8 monoclonal antibodies (mAbs) abrogates rejection; (c) CD4+ T cells from chronically infected mice proliferate in vitro to syngeneic myocardium antigens and induce heart graft destruction when injected in situ; (d) anti-CD4 treatment of chronically infected mice establishes long-term tolerance to syngeneic heart grafts; and (e) the state of tolerance is related to in vitro and in vivo unresponsiveness of the CD4+ T cells. These findings allow us to suggest that autoimmunity is the major mechanism implicated in the rejection of syngeneic heart tissues grafted into the pinna of the ear of mice chronically infected with T. cruzi. The similarity of the lesions to those found in humans suggests that autoimmunity is involved in the pathogenesis of chagasic cardiomyopathy in humans. Moreover, this could imply therapeutic strategies by reestablishing long-term tissue-specific tolerance with anti-CD4 mAb treatment, mediating anergy, or deleting the responder CD4+ T cells to heart tissue antigens.

[Experimental dilatation of the cecum and colon in rats. IV. Evaluation of a model produced by the use of lactose in the food of animals in the chronic phase of infection by the Colombia strain of T. cruzi]. / Dilatação experimental de ceco e cólon em ratos. IV. Avaliação de um modelo produzido pelo emprego de lactose na ração de animais em fase crônica da infecção pela cepa Colômbia de T. cruzi.

Female Wistar albino rats (30 day of age) were inoculated three times in intervals of 7 days with 1 x 10(7) epimastigote forms of T. cruzi and challenged 30 days after the last inoculation with 1 x 10(5) trypomastigote forms of the Colombia strain of T. cruzi. Rats of the same sex and age were used as controls. One-hundred-fifty days after inoculation the animals were allocated into 4 groups: Group I (control), divided into subgroup L (fed lactose for 4 weeks) and subgroup S (fed saccharose for 4 weeks); Group II (inoculated), divided into subgroup L (fed lactose for 4 weeks) and subgroup S (fed saccharose for 4 weeks); Group III (control), divided into subgroup L-S (fed lactose for 4 weeks and saccharose for the following 4 weeks) and subgroup S (fed saccharose for 8 weeks); and Group IV (inoculated), divided into subgroup L-S (fed lactose for 4 weeks and saccharose for the following 4 weeks) and subgroup S (fed saccharose for 8 weeks). The disaccharide (lactose or saccharose) was added to a standard laboratory diet, 25 g/100 g of the final weight of the diet. At the end of the experimental periods the animals were sacrificed in light ether anesthesia. The volume of the large intestine was measured, and the weights of the cecum and colon were recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

[Immune response to heart in rabbits: study of cellular and humoral immunity (author's transl)]. / Aspectos da resposta imune anti-coração em coelhos. Estudo da imunidade sérica e celular

Four groups of rabbits injected with cardiac tissue and complete Freund's adjuvant or aluminum hydroxide gel adjuvant and two groups only injected with aluminum hydroxide gel adjuvant or complete Freud's adjuvant were studied. The humoral and cellular immunity in immunized animals was studied using heart soluble and insoluble extracts. The tests results from hemagglutination, immunoelectrophoresis and immunofluorescence have presented cross-reactions among sera and hearts of the several species. Similar cross-reactions were not revealed by immunodiffusion. The immunoelectrophoresis and hemagglutination reactions were related to heart soluble extract and the immunofluorescence reactions were related to insoluble extract located in sarcolemal, subsarcolemal and intermyofibrilar sites. By hemagglutination, it was verified the presence of antibodies to heart and skeletal muscle in the antisera. Is was not possible to negative completely the reactivity of these antibodies to heart by absorptions with skeletal muscle. Inhibition tests to leucocytes migration revealed that leucocytes from immunized animals present migration inhibition when faced to antigens sedimented at.....56.500 g.

A proinflammatory factor in lymphocytes. Its role in the development of acute, non-immunological inflammatory reactions.

Drug-induced leucopenia renders rats hyporeactive to various inflammatory stimuli. Administration to leucopenic rats of suspensions of lymphocytes, sufficient to apparently correct the induced lymphocytopenia, led to a partial but marked reversal of the inhibited responses. Similar results were observed when lysates of lymphocytes or filtrates of the disintegrated cells were injected. Suspensions of polymorphonuclear granulocytes, on the contrary, were ineffective in producing a reversal of inhibited inflammatory reactions in leucopenic rats. The presence of a proinflammatory factor (LpIF) in lymphocytes, which might be involved in the modulation of acute inflammatory responses is suggested.