Visible light during mycelial growth and conidiation of Metarhizium robertsii produces conidia with increased stress tolerance

Light conditions during mycelial growth are known to influence fungi in many ways. The effect of visible-light exposure during mycelial growth was investigated on conidial tolerance to UVB irradiation and wet heat of Metarhizium robertsii, an insect-pathogenic fungus. Two nutrient media and two light regimens were compared. Conidia were produced on (A) potato dextrose agar plus yeast extract medium (PDAY) (A1) under dark conditions or (A2) under continuous visible light (provided by two fluorescent lamps with intensity 5.4 W m-2). For comparison, the fungus was also produced on (B) minimal medium (MM) under continuous-dark incubation, which is known to produce conidia with increased tolerance to heat and UVB radiation. The UVB tolerances of conidia produced on PDAY under continuous visible light were twofold higher than conidia produced on PDAY medium under dark conditions, and this elevated UVB tolerance was similar to that of conidia produced on MM in the dark. The heat tolerance of conidia produced under continuous light was, however, similar to that of conidia produced on MM or PDAY in the dark. Conidial yield on PDAY medium was equivalent when the fungus was grown either under continuous-dark or under continuous-light conditions.

Effects of dehydroepiandrosterone-sulfate (DHEA-S) and benznidazole treatments during acute infection of two different Trypanosoma cruzi strains

A significant role for hormones in regulating the balance of Th1- and Th2-associated cytokines with a role in modulating diseases has been accumulating. Previously, we reported that dehydroepiandrosterone (DHEA), the most abundant steroid hormone synthesized by the adrenal cortex, markedly reduced the blood and tissue parasites in experimentally Trypanosoma cruzi-infected rats. Based on these findings, the main purpose of this study was to investigate the effect of dehydroepiandrosterone-sulfate ester (DHEA-S) therapy alone or in combination with benznidazole (BNZ) (recommended in Brazil for the treatment of T. cruzi infection) will be effective during the acute phase of two different lineages of T. cruzi strains: type I (Y strain) and type II (Bolivia strain) of T. cruzi. Administration of either DHEA-S or BNZ alone or in combination significantly reduced the Y strain parasite load as compared with untreated. Furthermore treatment with DHEA-S resulted in Bolivia strain clearance. This protective effect of DHEA-S was associated with the host`s immune response, as evidence by enhanced levels of interferon-gamma and interleukin-2. DHEA-S treatment also increased peritoneal macrophages levels and nitrite production. DHEA-S treatment was effective in reducing the mortality rate as compared to BNZ alone or to combiner DHEA-S+BNZ treatment of T. cruzi Bolivia strain infected animals. These findings suggest that hormonal therapy may have a protective effect in the treatment of T. cruzi infection. (C) 2009 Elsevier GmbH. All rights reserved.

Acute Toxicity of Schizolobium parahyba Aqueous Extract in Mice

The herbal extract of Schizolobium parahyba leaves is used commonly in the Brazil central region to treat snakebites. This study evaluates the acute toxicological effects of Schizolobium parahyba aqueous extract in mice 24 h after intraperitoneal administration. Acute toxicity was evaluated using biochemical, hematological and histopathological assays. Alterations in the levels of transaminases, bilirubin, albumin and prothrombrin time were observed, and these are likely to occur due to hepatic injury, which was confirmed by light microscopy. Liver histopathological analysis revealed the presence of lymph plasmocitary inflammatory infiltrate, but no other histopathological alterations were observed in any of the other organs analysed. The data confirm the low toxicity of the extract of Schizolobium parahyba and provide a model for the selection of a dose that does not cause injuries in the organism. Copyright (C) 2009 John Wiley & Sons, Ltd.

Trypanocidal activity and acute toxicity assessment of triterpene acids

The present study evaluates the in vitro and in vivo trypanocidal activity of ursolic acid and oleanolic acid against the Bolivia strain of Trypanosoma cruzi. Their acute toxicity is also assessed on the basis of median lethal dose (DL50) determination and quantification of biochemical parameters. Ursolic acid is the most active compound in vitro, furnishing IC50 of 25.5 mu M and displaying 77% of trypomastigote lysis at a concentration of 128 A mu M. In agreement with in vitro assays, the results obtained for the in vivo assay reveals that ursolic acid (at a dose of 20 mg/Kg/day) provides the most significant reduction in the number of parasites at the parasitemic peak. Results concerning the LD50 assay and the biochemical parameters evaluated in the present study demonstrate that these substances can be safely used on an experimental basis.

Histamine Plays an Essential Regulatory Role in Lung Inflammation and Protective Immunity in the Acute Phase of Mycobacterium tuberculosis Infection

The course and outcome of infection with mycobacteria are determined by a complex interplay between the immune system of the host and the survival mechanisms developed by the bacilli. Recent data suggest a regulatory role of histamine not only in the innate but also in the adaptive immune response. We used a model of pulmonary Mycobacterium tuberculosis infection in histamine-deficient mice lacking histidine decarboxylase (HDC(-/-)), the histamine-synthesizing enzyme. To confirm that mycobacterial infection induced histamine production, we exposed mice to M. tuberculosis and compared responses in C57BL/6 (wild-type) and HDC(-/-) mice. Histamine levels increased around fivefold above baseline in infected C57BL/6 mice at day 28 of infection, whereas only small amounts were detected in the lungs of infected HDC(-/-) mice. Blocking histamine production decreased both neutrophil influx into lung tissue and the release of proinflammatory mediators, such as interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha), in the acute phase of infection. However, the accumulation and activation of CD4(+) T cells were augmented in the lungs of infected HDC(-/-) mice and correlated with a distinct granuloma formation that contained abundant lymphocytic infiltration and reduced numbers of mycobacteria 28 days after infection. Furthermore, the production of IL-12, gamma interferon, and nitric oxide, as well as CD11c(+) cell influx into the lungs of infected HDC(-/-) mice, was increased. These findings indicate that histamine produced after M. tuberculosis infection may play a regulatory role not only by enhancing the pulmonary neutrophilia and production of IL-6 and TNF-alpha but also by impairing the protective Th1 response, which ultimately restricts mycobacterial growth.

Association Among Microalbuminuria and Oxidative Stress Biomarkers in Patients With Type 2 Diabetes

Aim: Hyperglycemia in diabetes mellitus (DM) may be one of the most important factors responsible for the development of oxidative stress, which promotes the main complications in DM patients. Therefore, this study evaluated if the hyperglycemia could be related to oxidative stress biomarkers, lipid profile, and renal function in type 2 diabetes patients without clinic complications. Methods: Plasmatic malondialdehyde (MDA), serum protein carbonyl (PCO), serum creatinine levels, microalbuminuria, glycated hemoglobin, and lipid profile were analyzed in 37 type 2 diabetic patients and 25 subjects with no diabetes. Results: Serum creatinine levels were within the reference values, but microalbuminuria presented increased levels in all the patients compared with controls (P G 0.05) and above of the reference values. The MDA, PCO, low- density lipoprotein, and triglyceride levels showed positive correlation with microalbuminuria levels. Moreover, glycated hemoglobin presented positive correlation with MDA, PCO, and microalbuminuria levels. Conclusions: The hyperglycemia could be responsible for the increase of the microalbuminuria levels and for the oxidation process in lipids and proteins in DM patients. Therefore, we suggested that the microvascular lesion is a direct consequence from hyperglycemia and an indirect one from the increased oxidative stress. Malondialdehyde and protein carbonyl levels could be suggested as additional biochemical evaluation to verify tissue damage in type 2 DM patients.