Aerobic and anaerobic degradation of tannic acid on water samples from Monjolinho reservoir (Säo Paulo, SP, Brazil)

In order to describe the transformations of tannic acid during its degradation (under aerobic and anaerobic conditions) incubations were performed. To evaluate the oxygen consumption, the tannic acid was added to 1 L of water sample from Monjolinho's reservoir (22º00'S and 47º54'W); these solutions were aerated and the dissolved oxygen was monitored for 16 days, the anaerobic process was avoided. For the anaerobic and aerobic degradation, the dissolved organic carbon and the acid tannic concentrations were estimated on the samples days. The results were fitted to first-order kinetic model, being possible to verify that during the 16 days the oxygen uptake was 3.6 mg.L-1, the deoxygenation rate (kD)of this process was 0.39 day-1. The degradation coefficients were calculated through the decay of the tannic acid and organic carbon concentrations. In the aerobic process, the global decay coefficient (kG) was 0.36 day-1 and in the anaerobic 0.28 day-1. Overall, the obtained degradation coefficients suggest that the bacterioplankton of the Monjolinho's reservoir possess a high capacity of polyphenols degradation

Aerobic and anaerobic degradation of tannic acid on water samples from Monjolinho reservoir (São Carlos, SP, Brazil).

In order to describe the transformations of tannic acid during its degradation (under aerobic and anaerobic conditions) incubations were performed. To evaluate the oxygen consumption, the tannic acid was added to 1 L of water sample from Monjolinho's reservoir (22 degrees 00'S and 47 degrees 54'W); these solutions were aerated and the dissolved oxygen was monitored for 16 days, the anaerobic process was avoided. For the anaerobic and aerobic degradation, the dissolved organic carbon and the acid tannic concentrations were estimated on the samples days. The results were fitted to first-order kinetic model, being possible to verify that during the 16 days the oxygen uptake was 3.6 mg.L-1, the deoxygenation rate (kD) of this process was 0.39 day-1. The degradation coefficients were calculated through the decay of the tannic acid and organic carbon concentrations. In the aerobic process, the global decay coefficient (kG) was 0.36 day-1 and in the anaerobic 0.28 day-1. Overall, the obtained degradation coefficients suggest that the bacterioplankton of the Monjolinho's reservoir possess a high capacity of polyphenols degradation.

D values of Salmonella enteritidis isolates and quality attributes of shell eggs and liquid whole eggs treated with irradiation.

Irradiation sensitivity of five Salmonella enteritidis isolates inoculated either on the surface or inside of whole shell eggs were determined. The shell eggs were irradiated at doses of 0, 0.5, 1.0, and 1.5 kGy. A minimal dose of 0.5 kGy was sufficient to eliminate all the isolates from the surface of whole eggs; however, the same isolates were more resistant to irradiation when present inside the eggs. The ATCC 13076 isolate was significantly more sensitive to irradiation, with a D value of 0.32 kGy, than the other four isolates from animal origin. Irradiation D values of the latter ranged from 0.39 to 0.41 kGy. Liquid whole eggs were also inoculated (2.4 x 10(6) cells per milliliter) with two S. enteritidis isolates and were heat-treated at 50 C for 0, 20, 40, or 60 min followed by irradiation at 0, 0.25, 0.5, 0.75, or 1.0 kGy. The results indicate that mild heating prior to irradiation was ineffective in reducing the irradiation D values. However, on the basis of the D values obtained, an irradiation dose of 1.5 kGy should be sufficient to reduce Salmonella counts by approximately 4 log10 in both whole shell and liquid eggs. Results also indicate that color and thermal characteristics of the whole or liquid eggs were unaffected by a 1.5-kGy dose of irradiation.

Splenocyte membrane changes and immunosuppression during infection and reinfection with Trypanosoma cruzi.

Antisera to epi- and trypomastigote forms of Trypanosoma cruzi were used to detect trypanosome antigens on the surface of lymphocytes from infected mice. Only the anti-trypomastigote serum could recognize antigens expressed transiently on the splenocyte membranes from infected animals. The number or structural configuration of Concanavalin A receptors was similarly affected and a clear correlation was seen between these two types of membrane changes and the immunosuppression to mitogens and SRBC presented by the infected mice. Reinfected animals did not show evidences of trypanosome proliferation in blood or tissues nor trypomastigote antigens on splenocytes, but presented a less intense, transient immunosuppression as measured by responsiveness to mitogens and SRBC, suggesting that the primed immune system can eliminate the new parasite inoculum before the host is immunosuppressed and also that the liberation of strong immunosuppressor trypomastigote antigens induce the new state of suppression.

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

Tripomastigotas de sangue da cepa Y de T. cruzi mostraram uma forte inibiçäo da resposta de transformaçäo blástica a mitógenos de células T e B, nas estirpes C3H/He, C57BL/6 e BALB/cJ de camundongos, enquanto epimastigotas de cultura da cepa Y mantidos em meio que permite o crescimento dos parasitas a 26-, 30-, 34- e 37-C mostraram um forte efeito estimulante, que foi inclusive maior que o efeito dos mitógenos isolados. Os efeitos de inibiçäo e de estimulaçäo foram dependentes da dose. O efeito estimulante dos epimastigotas também foi dependente da temperatura, encontrando-se maiores índices de estimulaçäo à medida que a temperatura da cultura dos parasitas foi aumentada. Parasitas vivos, metabolicamente ativos, parecem ser necessários para a obtençäo de uma maior estimulaçäo dos linfócitos, o que sugere um papel potencial dos metabólitos segregados como ativadores policlonais dos linfócitos dos camundongos

Interferon-gamma binds to high and low affinity receptor components on murine macrophages.

Interferon-gamma (IFN-gamma), a glycoprotein secreted by antigen-or mitogen-activated lymphocytes, modulates the activities of lymphocytes and macrophages. For mouse macrophages, murine IFN-gamma (MuIFN-gamma) stimulates several functions, including phagocytosis, tumoricidal activity, and the increased expression of Ia and H-2 antigens of the major histocompatibility complex. Recent reports have suggested that IFN-gamma specifically binds to cell surface receptors corresponding to a single class of binding sites with a Kd of 10(-8) to 10(-10) M. We present evidence that, on the murine macrophage cell line WEHI-3, MuIFN-gamma specifically binds to two classes of binding sites with Kd of 9.1 X 10(-11) M (500 sites/cell) and 2.7 X 10(-9) M (4400 sites/cell). The higher affinity sites most likely represent the physiologically relevant receptors that mediate at least some of the actions of MuIFN-gamma.

Differential effect of culture epimastigotes and blood-form trypomastigotes 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, C57BL/6 and BALB/cJ strains of mice, while culture epimastigotes of the Y strain kept in a medium that allows parasite growth at 26 degrees, 30 degrees, 34 degrees and 37 degrees 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 increased stimulation 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.

Cell wall analysis of an adenine-requiring mutant of the yeast-like form of Paracoccidioides brasiliensis strain IVIC Pb9.

An adenine-requiring mutant of Paracoccidioides brasiliensis strain IVIC Pb9 was isolated after treatment of the yeast-like (Y) form with nitrosoguanidine. Cell wall analysis of this mutant (strain IVIC Pb141) showed an increase in the amount of alpha-1,3-glucan and a virtual disappearance of the antigenic galactomannan. At the same time, a higher degree of virulence was observed for the mutant. These results agree with the hypothesis presented before (16) about a relationship between cell wall polysaccharides and pathogenicity in P. brasiliensis.

Host-parasite relationships in the yeastlike form of Paracoccidioides brasiliensis strain IVIC Pb9.

The yeastlike form of Paracoccidioides brasiliensis strain IVIC Pb9 reduced the amount of alpha-1,3-glucan in its cell wall from 45 to 3% when subcultured in vitro for several years. This strain regained its alpha-1,3-glucan up to 25% of the total cell wall when grown in vivo. A mutant strain of P. brasiliensis Pb9, named IVIC Pb140, reported to have 1,3-mannan instead of alpha-glucan in the cell wall, could not be recovered from experimentally infected animals. The existence of some relationship between the presence of alpha-1,3-glucan in the cell wall of the yeastlike form and the pathogenicity of this fungus is suggested in this report.