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Biomedical subjects

S Arruda

Publications and source records attributed to S Arruda.

18 recordsLinked to original sources
PubMed2002

B-cell infiltration and frequency of cytokine producing cells differ between localized and disseminated human cutaneous leishmaniases.

Biopsies from human localized cutaneous lesions (LCL n = 7) or disseminated lesions (DL n = 8) cases were characterized according to cellular infiltration,frequency of cytokine (IFN-gamma, TNF-alpha) or iNOS enzyme producing cells. LCL, the most usual form of the disease with usually one or two lesions, exhibits extensive tissue damage. DL is a rare form with widespread lesions throughout the body; exhibiting poor parasite containment but less tissue damage. We demonstrated that LCL lesions exhibit higher frequency of B lymphocytes and a higher intensity of IFN-gamma expression. In both forms of the disease CD8+ were found in higher frequency than CD4+ T cells. Frequency of TNF-alpha and iNOS producing cells, as well as the frequency of CD68+ macrophages, did not differ between LCL and DL. Our findings reinforce the link between an efficient control of parasite and tissue damage, implicating higher frequency of IFN-gamma producing cells, as well as its possible counteraction by infiltrated B cells and hence possible humoral immune response in situ.

Adolescent↗
PubMed2001

In vivo lymphocyte activation and apoptosis by lectins of the Diocleinae subtribe.

This paper reports the overall effects of three lectins, extracted from Canavalia brasiliensis, Dioclea violacea, and D. grandiflora, on BALB/c mice popliteal draining lymph nodes. These lectins have presented high stimulatory capacity on lymph node T cells. Additionally, they were able to induce apoptosis and inflammation (frequently associated with high endothelial venule necrosis). The data presented here suggest that the Diocleinae lectins studied can stimulate in vivo T cell activation and apoptosis, as well as present important side effects.

Amino Acid Sequence↗
PubMed2001

Revisiting proteus: do minor changes in lectin structure matter in biological activity? Lessons from and potential biotechnological uses of the Diocleinae subtribe lectins.

Significant differences in function have been observed among lectins structurally similar to concanavalin A, but their high homology with this widely used lectin has kept them in obscurity. The observation of large differences in the potency of many of these Diocleinae lectins as stimulators of Interferon-g production by human peripheral blood mononuclear cells has lead to a major effort to unravel their chemical structure and biological activity. Modeling studies of some of these lectins reveal conformational changes in side chains of some residues involved in the carbohydrate-binding site, with possible effects on the ability of these proteins to recognize specific carbohydrate structures. Additionally, all them constitute in fact a mixture of isolectins, which in different proportions could lead to diverse effects. The present review of the biological actions of Diocleinae lectins includes several in vitro and in vivo immunological findings, as well as their effects on insect growth and reproduction. In these systems Diocleinae lectins proved to be quite diverse in their potency. Such diversity in the biological activity of highly related proteins recalls the origin of the name protein: like Proteus, the capability of assuming various forms is the essential feature of this class of molecules.

Amino Acid Sequence↗
PubMed1999

Lectin-induced nitric oxide production.

Considering that nitric oxide (NO) may be involved in anti-tumoral and anti-parasite lectin effects, in this report we investigated whether lectin induces NO production. Lectins from Canavalia brasiliensis, Dioclea grandiflora, Pisum arvense (PAA), and concanavalin A induced murine peritoneal cells to produce NO in vitro. PAA induced similar levels to that obtained with lipopolysaccharide plus interferon-gamma. NO production by adherent cells was significantly lower than that of unfractionated cells, suggesting a combination of lectin stimuli directly on macrophages and via lymphocyte stimulation. Ex vivo experiments showed that cells stimulated in vivo could maintain NO production in vitro without further stimuli. NO synthesis blockage in vivo can significantly increase cell numbers in draining lymph nodes after lectin injection compared to unblocked controls, suggesting an in vivo association of lectin stimuli and NO production. Taken together these data show that lectins can induce NO production both in vitro and in vivo.

Animals↗
PubMed1998

Cell-mediated immune responses and cytotoxicity to mycobacterial antigens in patients with tuberculous pleurisy in Brazil.

Evaluating human immune response to defined Mycobacterium tuberculosis antigens in patients with different clinical forms of tuberculosis may help in elucidating pathogenesis and in vaccine development. In the present report we evaluated the lymphocyte proliferation, cytokine production and natural killer cell cytotoxicity as parameters to screen four mycobacterial recombinant antigens. Pleural fluid mononuclear cells (PFMC) and peripheral blood mononuclear cells (PBMC) from 13 HIV-negative patients with tuberculous pleurisy, living in a tropical region of Brazil were used in these assays. Crude M. tuberculosis antigen and recombinant 70-, 65- and 38-kDa mycobacterial antigens, induced greater proliferation in PFMC than in PBMC. IFN-gamma, TNF-alpha, IL-4 and IL-10 were evaluated in the PFMC supernatants stimulated by these antigens. Both crude and 70-kDa antigens induced higher levels of IFN-gamma, TNF-alpha and IL-10. There was a significant positive correlation between IFN-gamma and the proliferative response induced by crude M. tuberculosis antigen, and an inverse correlation was identified between IL-10 and cell proliferation. IL-4 was not detected in the supernatants of pleural fluid mononuclear cell cultures stimulated by either crude, or recombinant antigens. TNF-alpha was detected in variable amounts in supernatants of PFMC stimulated by all antigens tested. Natural killer cytotoxicity was induced by both crude and 70-kDa antigen. Our results demonstrate that cells present at the site of disease recognized three of the antigens screened, as shown by lymphocyte proliferation and production of regulatory and inflammatory cytokines, and the results obtained with PFMC were consistently higher than those obtained with homologous PBMC.

Antibodies, Monoclonal↗
PubMed1997

Placebo-controlled study of tianeptine in major depressive episodes.

The efficacy and safety of tianeptine were compared, in the course of a multicentre randomised, double-blind, parallel group study, to those of placebo in the treatment of Major Depressions and Bipolar Disorder, Depressed with or without melancholia, without psychotic features. After a 1-week run-in placebo period, 126 depressed out-patients presenting DSM-III-R Major Depression or Bipolar Disorder, Depressed, with a total MADRS score of at least 25, were treated for 42 days with either tianeptine (25-50 mg/day) or placebo. Efficacy assessments were MADRS, CGI, HARS, Zung Depression Self Rating Scale and a VAS. Better efficacy of tianeptine was shown, and confirmed by covariance analyses, in final MADRS scores of the intention-to-treat population, of patients treated for at least 14 days and of completers; also in CGI items 1 and 2, MADRS item 10, and VAS. The results confirmed the efficacy of tianeptine (mean dosage: 37.5 mg/day) in the treatment of Major Depression and Bipolar Disorder, Depressed, with or without melancholia, compared to placebo. Tianeptine's acceptability did not differ from that of placebo. For adverse events, a higher incidence of headaches was found with tianeptine.

Adolescent↗
PubMed1993

Cloning of an M. tuberculosis DNA fragment associated with entry and survival inside cells.

Mycobacterium tuberculosis infects one-third of the world's human population. This widespread infection depends on the organism's ability to escape host defenses by gaining entry and surviving inside the macrophage. DNA sequences of M. tuberculosis have been cloned; these confer on a nonpathogenic Escherichia coli strain an ability to invade HeLa cells, augment macrophage phagocytosis, and survive for at least 24 hours inside the human macrophage. This capacity to gain entry into mammalian cells and survive inside the macrophage was localized to two distinct loci on the cloned M. tuberculosis DNA fragment.

Bacterial Proteins↗
PubMed1992

IL-4 receptor signal transduction in human monocytes is associated with protein kinase C translocation.

IL-4 regulates B cell differentiation and monocyte functions. Protein kinases, such as kinase C (PKC), transduce receptor signals. The involvement of PKC in IL-4R signaling was investigated in human monocytes. Treatment with IL-4 (10 ng/ml) for 10 min resulted in a significant redistribution of the PKC activity from cytosol to nuclear fraction. Total PKC activity localized in the nuclear fraction of IL-4-treated and control monocytes was, respectively, 68 and 19%. In contrast, similar PKC activity was found in membrane fraction of IL-4-treated and control cells. The kinetics of IL-4-mediated redistribution of PKC activity to the nuclear fraction were rapid. Within 30 s of IL-4 exposure, 29% of the total PKC activity localized in the nuclear fraction as compared to 15% in control monocytes and increased to 69% at 10 min. The PKC activity in the nuclear fraction appears to be a sequestered form. Extraction with Triton X-100 and additional sonication were required for functional assay of PKC activity. Additional support for PKC involvement in IL-4R signaling is provided by the dose-dependent effect of IL-4 on PKC activity and the abrogation of this effect after heat denature and immunoabsorption of IL-4. Furthermore, electron microscope examination and subcellular marker enzyme assays excluded significant contamination of the nuclear fraction by plasma membranes or subcellular organelles and IL-4 altering membrane disruption. The data presented indicate that IL-4R signaling in human monocytes involves PKC translocation to a nuclear fraction.

Cell Compartmentation↗
PubMed1992

Interleukin-3 induces antimicrobial activity against Leishmania amazonensis and Trypanosoma cruzi and tumoricidal activity in human peripheral blood-derived macrophages.

The ability of interleukin-3 (IL-3) to induce antimicrobial and tumoricidal activity was evaluated. Macrophages infected with two intracellular protozoa, Leishmania amazonensis or Trypanosoma cruzi, were treated with cytokines. IL-3 induced a dose-dependent enhancement of microbistasis against leishmanias, and the activity of IL-3 (100 ng/ml) was comparable to that of gamma interferon (IFN-gamma) (1,000 U/ml). In addition, IL-3 in combination with either granulocyte-macrophage colony-stimulating factor (GM-CSF) or macrophage CSF (M-CSF) or with IFN-gamma reduced infection and lowered the required dose. IL-3 similarly activated macrophages to inhibit intracellular replication of T. cruzi. Furthermore, IL-3 induced antibody-independent tumoricidal activity against melanoma cells that was dose dependent and comparable to that of lipopolysaccharide and GM-CSF. The mechanisms by which IL-3 induced antimicrobial activity may involve at least the augmentation of oxidative capacity. IL-3, at concentrations of 0.5 ng/ml or greater, led to a significantly increased oxidative burst which paralleled the inhibition of protozoan replication. The enhancement of oxidative capacity by IL-3 (5 ng/ml or higher) was comparable to that of IFN-gamma. The induction of tumoricidal activity was associated with the production of tumor necrosis factor alpha (TNF-alpha), which in this system may feed back to enhance the macrophage inhibition of leishmanias, as demonstrated by neutralization of IL-3 activation by anti-TNF-alpha antibody. Thus, peripheral blood macrophages remain responsive to IL-3, as demonstrated by enhanced antimicrobial and tumoricidal activity. IL-3 may have potential clinical applications because of these properties and its effect on myelopoiesis.

Animals↗