Gastric acid secretion response in the Cebus apella: a monkey model of chronic Chagas disease

The objective was to study the secretory pattern, both basal and stimulated either by histamine (0.1 mg/kg) or pentagastrin (64 ug/kg) in eighteen Cebus apella monkeys chronically infected with different T. cruzi strains (CA1, n=10; Colombian, n=4 and Tulahuen, n=4) and to describe the morphological findings in the gastrointestinal tract in twelve infected (6 sacrificed and 6 spontaneously dead) and four healthy monkeys. All infected monkeys and 35 healthy ones were evaluated by contrast X-ray examination. No differences were observed in basal acid output between control and infected groups. Animals infected with the Tulahuen and Colombian strains showed significant lower values of peak acid output in response to histamine or pentagastrin (p<0.01 and p<0.05 respectively; "t" test) in comparison to the controls. Barium contrast studies showed enlargement and dilatation of the colon in three infected animals. Histopathological lesions were seen in 75% of the autopsied animals either in colon alone (33%) or both, in colon and esophagus (42%). The normal secretion observed in the CA1 infected group could be due to a lower virulence of the strain, a lower esophagic tropism or the necessity of a longer post-infection time to cause lesions.

IL-2 AND IFN-g, BUT NOT IL-4 SECRETION BY PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMC) ARE RELATED TO CD4+ T CELLS AND CLINICAL STATUS IN BRAZILIAN HIV-1-INFECTED SUBJECTS

It has been reported that production of IL-2 and IFN-g, known as T-helper type 1 cytokines, by peripheral mononuclear cells (PBMC) decreases with progression of HIV infection. In contrast, IL-4 and IL-10 production, Th2 cytokine profile, increases with HIV disease progression. PBMC were evaluated from 55 HIV-infected subjects from Divisão de Imunologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, to "in vitro" cytokines production after 24 hours of stimulation with PHA. Low levels of IL-4 production in both HIV- infected patients and normal subjects, were detected. The patients with CD4+ T cell counts <200 showed a significant decrease of IL-2 and IFN-g production compared to controls. Patients with higher counts of CD4+ T cells (either between 200-500 or >500 cells/mm3) also showed decreased production of IL-2 that was not statistically significant. There was a correlation between IL-2 and IFN-g release with CD4+ T cells counts. HIV-1-infected individuals with CD4+ T cells >500 cells/mm3 showed increased levels of IL-2 and IFN-g, than individuals with CD4+ T cells <500 cells/mm3. In conclusion, we observed a decline of IL-2 and IFN-g production at advanced HIV disease. IL-4 production was not affected during HIV infection. Taken together, these findings suggest that the cytokine profile might be influenced by the HIV infection rather than the cause of disease progression.

Secretion of five extracellular enzymes by strains of chromoblastomycosis agents

The gelatinase, urease, lipase, phospholipase and DNase activities of 11 chromoblastomycosis agents constituted by strains of Fonsecaea pedrosoi, F. compacta, Phialophora verrucosa, Cladosporium carrionii, Cladophialophora bantiana and Exophiala jeanselmei were analyzed and compared. All strains presented urease, gelatinase and lipase activity. Phospholipase activity was detected only on five of six strains of F. pedrosoi. DNase activity was not detected on the strains studied. Our results indicate that only phospholipase production, induced by egg yolk substrate, was useful for the differentiation of the taxonomically related species studied, based on their enzymatic profile.

Excretion-secretion products and proteases from live Sporothrix schenckii yeast phase: immunological detection and cleavage of human IgG

Antigenic preparations from Sporothrix schenckii usually involve materials from mixed cultures of yeast and mycelia presenting cross-reactions with other deep mycoses. We have standardized pure yeast phase with high viability of the cells suitable to obtain specific excretion-secretion products without somatic contaminations. These excretion-secretion products were highly immunogenic and did not produce noticeable cross-reactions in either double immunodiffusion or Western blot. The antigenic preparation consists mainly of proteins with molecular weights between 40 and 70 kDa, some of them with proteolytic activity in mild acidic conditions. We also observed cathepsin-like activity at two days of culture and chymotrypsin-like activity at four days of culture consistent with the change in concentration of different secreted proteins. The proteases were able to cleave different subclasses of human IgG suggesting a sequential production of antigens and molecules that could interact and interfere with the immune response of the host.

The pineal neurohormone melatonin and its physiologic opiatergic immunoregulatory role

The pineal gland functions as a neuroendocrine transducer that coordinate the organism response to changing environmental stimuli such as light and temperature. The main and best known pineal neurohormone is melatonin that is synthesized and released in a circadian fashion with a peak during the night darkness hours. We have recently reported that melatonin exerts important immuno regulatory functions. Here we describe the astonishing property of exogenous melatonin which is able to counteract completely the depressive effect of anxiety-restraint stress and/or of corticosterone on thymus weight, andibody production and antiviral responses. This effect seems to be mediated by antigen-activated T cells via an opiatergic mechanism.

Inhibition of gastric secretion by a water extract from Baccharis triptera, Mart

Baccharus triptera Mart, is a widespread Compositae used in Brazilian folk medicine to treat gastrointestinal disturbances, rheumatic disease, mild fever, diabetes and as an anti-helminthic. Water extract of small branches of the plant (WE) administered to mice and rats (0.1 to 2 g/Kg, p.o) did not alter spontaneous motor activity, sleeping time induced by barbiturates or the tailflick response in mice. The extract decreased by 40 por cento the number of writhings induced by 0.8 por cento scetic acid, i.p., but did not influence paw edema induced by carrageenan or dextran in rats WE (2g/Kg, p.o.) decreased the intestinal transit of charcoal in mice by 20//. Gastric secretion in pylorus ligated rats was reduced after treatment with WE (1 and 2 g/Kg. i.p. or intraduodenal and the gastric pH was raised. The extract (1 g/Kg, p.o.) prevented gastric ulcers induced in rats by immobilization at 4ºC, but not those induced by indomethacin (10 mg/Kg, s.c.). The results indicate that WE may relieve gastrointestinal disorders by reducing acid secretion and gastrointestinal hiperactivity. Neither analgesic nor anti-inflammatory activities were detectable.

The water extract of Coleus barbatus Benth decreases gastric secretion in rats

Coleus barbatus (Labiatae) Benth is popularly used in Brazil "for the healing of liver and stomach diseases". The water extract (WE 1 to 10 g/Kg, p.o.) of stem and leaves given to rats and mice did not induce signs of intoxication. Preveious treatment of mice with WE (1 g/kg, p.o.) shortened the sleeping time induced by pentobarbital (50 mg/Kg, i.p.) by 37 por cento, althoyugh the extract alone did not increase the spontaneous activity nor did it induce hyperexcitability. In mice WE (2 g/Kg, p.o.) increased the intestinal transit of charcoal by 30 por cento, while reduced gastric secretions ion rats treated with WE (2g/Kg intraduodenal) 3,9 ± 1.0 to 0.5 ± 0.2 ml/4h, respectively). The treatment also reduced the total acid secretion from 34.4 ± 11.0 to 2.7 ± 0.5 mEq/l and raisedgastric pH from 2.2 ± 0.3 to 6.5 ± 0.8. Treatment with WE (2g/Kg, p.o.) protected against gastric ulcers induced by stress (5.3 ± 1.6 and 1.5 ± 0.5 ulcers/cm²), but did nor protect against indonethacin induced ulcers. The results show that the water extract of C barbatus Benth produces mild stimulation of thecentral nervous system and increases intestinal movements. The extract also reduces gastric secretion indicating an antidyspeptic activity, and protects against gastric ulcers induced by stress.

Rapid in vitro detection of HIV-1-specific antibody secretion by cells-culture with virus antigens

The present report describes an alternative method for in vitro detection of HIV-1 -specific antibody secretion in 24h of culture employing as stimulant of peripheral blood mononuclear cells the disrupted inactivated whole virus adsorbed onto microwells in a commercial ELISA kit plates. The results obtained from this technique have showed high sensitivity and specificity since it was capable of detecting HIV-1 infection early after birth. There were neither false-positivity nor false-negativity when blood samples obtained from HIV-1 seronegative asymptomatic individuals, and HIV-1 seropositive adult patients were analized. This rapid, low cost, simple, highly sensitive and specific assay can be extremely useful for early diagnosis of pediatric HIV infection.

Role of CD8+ T cells in endogenous interleukin-10 secretion associated with visceral leishmaniasis

This study examined the role and source of endogenous interleukin-10 (IL) secretion in visceral leishmaniasis (VL). The amounts of endogenous and Leishmania specific IL-10 and interferon-gamma (IFN) secreted by peripheral blood mononuclear cells (PBMC) from VL patients were compared. The correlation coefficient between endogenous IL-10 secretion and Leishmania specific IFN-gamma was -0.77, suggesting a major role for endogenous IL-10 secretion in VL. The effects of CD4+ and CD8+ T cell clones, isolated from a treated VL patient, on IL-10 secretion were assayed by mixing the clones with autologous, inactivated PBMC. The CD8+ clones mediated increased levels of IL-10 secretion in the presence of PBMC alone suggesting that CD8+ T cells may mediate endogenous IL-10 secretion.

Mycobacterium bovis BCG but not Mycobacterium leprae induces TNF-alpha secretion in human monocytic THP-1 cells

In this study, we compared the level of TNF-alpha secretion induced in monocytic THP-1 cells after phagocytosis of Mycobacterium leprae, the causative agent of leprosy, and M. bovis BCG, an attenuated strain used as a vaccine against leprosy and tuberculosis. The presence of M. leprae and BCG was observed in more than 80% of the cells after 24 h of exposure. However, BCG but not M. leprae was able to induce TNF-alpha secretion in these cells. Moreover, THP-1 cells treated simultaneously with BCG and M. leprae secreted lower levels of TNF-alpha compared to cells incubated with BCG alone. M. leprae was able, however, to induce TNF-alpha secretion both in blood-derived monocytes as well as in THP-1 cells pretreated with phorbol myristate acetate. The inclusion of streptomycin in our cultures, together with the fact that the use of both gamma-irradiated M. leprae and heat-killed BCG gave similar results, indicate that the differences observed were not due to differences in viability but in intrinsic properties between M. leprae and BCG. These data suggest that the capacity of M. leprae to induce TNF-alpha is dependent on the stage of cell maturation and emphasize the potential of this model to explore differences in the effects triggered by vaccine strain versus pathogenic species of mycobacteria on the host cell physiology and metabolism.

Detection of Mycobacterium leprae DNA by polymerase chain reaction in the blood and nasal secretion of Brazilian household contacts

DNA samples from blood and nasal swabs of 125 healthy household contacts was submitted to amplification by polymerase chain reaction (PCR) using a Mycobacterium leprae-specific sequence as a target for the detection of subclinical infection with M. leprae.All samples were submitted to hybridization analysis in order to exclude any false positive or negative results. Two positive samples were confirmed from blood out of 119 (1.7%) and two positive samples from nasal secretion out of 120 (1.7%). The analysis of the families with positive individuals showed that 2.5% (n = 3) of the contacts were relatives of multibacilary patients while 0.8% of the cases (n = 1) had a paucibacilary as an index case. All positive contacts were followed up and after one year none of them presented clinical signs of the disease. In spite of the PCR sensitivity to detect the presence of the M. leprae in a subclinical stage, this molecular approach did not seem to be a valuable tool to screen household contacts, since we determined a spurious association of the PCR positivity and further development of leprosy.

Dengue-2 and yellow fever 17DD viruses infect human dendritic cells, resulting in an induction of activation markers, cytokines and chemokines and secretion of different TNF-α and IFN-α profiles

Flaviviruses cause severe acute febrile and haemorrhagic infections, including dengue and yellow fever and the pathogenesis of these infections is caused by an exacerbated immune response. Dendritic cells (DCs) are targets for dengue virus (DENV) and yellow fever virus (YF) replication and are the first cell population to interact with these viruses during a natural infection, which leads to an induction of protective immunity in humans. We studied the infectivity of DENV2 (strain 16681), a YF vaccine (YF17DD) and a chimeric YF17D/DENV2 vaccine in monocyte-derived DCs in vitro with regard to cell maturation, activation and cytokine production. Higher viral antigen positive cell frequencies were observed for DENV2 when compared with both vaccine viruses. Flavivirus-infected cultures exhibited dendritic cell activation and maturation molecules. CD38 expression on DCs was enhanced for both DENV2 and YF17DD, whereas OX40L expression was decreased as compared to mock-stimulated cells, suggesting that a T helper 1 profile is favoured. Tumor necrosis factor (TNF)-α production in cell cultures was significantly higher in DENV2-infected cultures than in cultures infected with YF17DD or YF17D/DENV. In contrast, the vaccines induced higher IFN-α levels than DENV2. The differential cytokine production indicates that DENV2 results in TNF induction, which discriminates it from vaccine viruses that preferentially stimulate interferon expression. These differential response profiles may influence the pathogenic infection outcome.

Intraocular pressure and tear secretion in Saanen goats with different ages

This study aimed to compare the normal intraocular pressure (IOP) and tear secretion, by means of applanation tonometry and the Schirmer tear test-1 (STT-1), in goats of the Saanen breed with different ages, and at different time points. Thirty six goats, free of ocular abnormalities, were grouped into three different age categories (n=12), animals with 45, 180 and 549 days of age. STT-1 and IOP measurements were carried out always at 9:00am and 7:00pm, during three consecutive days. Results were evaluated statistically (P<0.05). Regarding the time of the day, overall IOP values were significantly lower at 7:00 pm (P<0.001) in individuals with 45 days of age; whereas STT-1 values were significantly higher at 7:00pm (P=0.004) in goats with 549 days of age. Considering the sum of three days, both parameters were significantly lower in individuals with 45 days of age (P<0.001). Intraocular pressure and tear secretion values increase until 180 days of age in the Saanen breed of goats.