Antibacterial activity of Baccharis trimera (Less.) DC. (carqueja) against bacteria of medical interest

Baccharis trimera (Less.) (Asteraceae), popularly know as "carqueja", is a species commonly used in folk medicine for the treatment or prevention of diseases. In this context, the purpose of this work was to study the antibacterial activity of crude hydroalcoholic extract from Baccharis trimera against Gram-positive bacterial strains (Staphylococcus aureus ATCC 29213, Staphylococcus saprophyticus ATCC 15305, Staphylococcus epidermidis ATCC 12228, Enterococcus faecalis ATCC 19433) and Gram-negative bacteria (Escherichia coli EHEC ATCC 43895, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 27736, Salmonella typhi ATCC 19430) of clinical interest. Antibacterial susceptibility was evaluated by broth microdilution assay following the CLSI (formerly the NCCLS) guidelines. The extract from B. trimera showed antibacterial activity against Gram-positive bacteria and the most interesting result was obtained against S. epidermidis that presented Minimal Inhibitory Concentration of 250μg/mL. These results indicate that B. trimera have bacterisostatic potential against Gram-positive bacterial strains of medical interest and could serve as a base for further studies on the use of isolated compounds from this species as future antimicrobials.

Silicon in plant disease control

All essential nutrients can affect the incidence and severity of plant diseases. Although silicon (Si) is not considered as an essential nutrient for plants, it stands out for its potential to decrease disease intensity in many crops. The mechanism of Si action in plant resistance is still unclear. Si deposition in plant cell walls raised the hypothesis of a possible physical barrier to pathogen penetration. However, the increased activity of phenolic compounds, polyphenol oxidases and peroxidases in plants treated with Si demonstrates the involvement of this element in the induction of plant defense responses. The studies examined in this review address the role of Si in disease control and the possible mechanisms involved in the mode of Si action in disease resistance in plants.

Chagas' disease and social security: a case-control study in an urban area, Goiás, Brazil

One hundred and twenty subjects with Chagas' cardiopathy and 120 non-infected subjects were randomly selected from first time claimants of sickness benefits in the National Institute of Social Security (INPS) in Goiás. Cases of Chagas' cardiopathy were defined based on serological test, history of residence in an endemic area and, clinical and/or electrocardiogram (ECG) alterations suggestive of Chagas' cardiomyopathy. Controls were defined as subjects with at least two negative serological tests. Case and controls were compared in the analysis for age, sex, place of birth, migration history, socio-economic level, occupation, physical exertion at work, age at affiliation and years of contribution to the social security scheme, clinical course of their disease and ECG abnormalities. Chagas' disease patients were younger than other subjects and predominantly of rural origin. Non-infected subjects presented a better socio-economic level, were performing more skilled activities and had less changes of job than cases. No important difference was observed in relation to age at affiliation to INPS. About 60% of cases have claimed for benefits within the first four years of contribution while among controls this proportion was 38.5%. Cases were involved, proportionally more than controls, in "heavy" activities. A risk of 2.3 (95%CL 1.5 - 4.6) and 1.8 (95%CL 1.2- 3.5) was obtained comparing respectively "heavy" and "moderate" physical activity against "light". A relative risk of 8.5 (95%CL 4.9 - 14.8) associated with the presence of cardiopathy was estimated comparing the initial sample of seropositive subjects and controls. A high relative risk was observed in relation to right bundle branch block (RR = 37.1 95%CL = 8.8 - 155.6) and left anterior hemiblock (RR = 4.4, 95%CL = 2.1 - 9.1).

Radiometric detection of metabolic activity of Paracoccidioides brasiliensis and its susceptibility to amphotericin B and diethylstilbestrol

Paracoccidioidomycosis (South American blastomycosis) is a systemic disease, strikingly more frequent in males, caused by the dimorphic fungus Paracoccidioides brasiliensis. A radiometric assay system has been applied to study the metabolic activity and the effect of drugs on this fungus "in vitro". The Y form of the yeast, grown in liquid Sabouraud medium was inoculated into sterile reaction vials containing the 6B aerobic medium along with 2.0 μCi of 14C-substrates. Control vials, prepared in the same way, contained autoclaved fungi. To study the effects of amphotericin B (AB) (0.1 and 10 μg/ml) and diethylstilbestrol (DSB) (1.0, 5.0 and 10 μg/ml) extra controls with live fungi and no drug were used. All vials were incubated at 35°C and metabolism measured daily with a Bactec instrument. 14CO2 production by P. brasiliensis was slow and could be followed for as long as 50 days. AB at 10mg/ml and DSB at 5 μg/ml inhibited the metabolism and had a cidal effect on this fungus. The results with DSB might explain the low incidence of the disease in females. This technique shows promise for studying metabolic pathways, investi gating more convenient 14C-substrates to expedite radiometric detection and for monitoring the effects of other drugs and factors on the metabolism of P. brasiliensis "in vitro".

Immunopathology of human schistosomiasis mansoni: II. NK activity and stimulation by specific antigen

Sixteen S. mansoni infected and untreated patients (5 with recent infection and 11 with chronic disease) were evaluated for their in vitro natural killer (NK) activity against the NK sensitive target K562 cell line. NK levels in 9 out of 11 patients (82%) with chronic disease were significantly lower (mean = 15 ± 6%),compared with patients recently infected (mean = 41 ± 9% p < 0.001) and with the control group (mean = 38 ± 13% p < 0.001). However, both patients and controls NK activity was stimulated by soluble adult worm antigens (SAWA), indicating that NK function even in the chronic stage of the infection is able to respond to the parasite antigens. These results suggest the possibility of NK cell participation as effector mechanism against S. mansoni.

Lymphocyte subpopulations and neutrophil function in chronic human Chagas' disease

The absolute numbers of total leukocytes, lymphocytes, T cells, helper/inducer, suppressor/cytotoxic and B cells were decreased in the peripheral blood of patients with chronic Chagas' disease. Since antilymphocyte antibodies were present only in a minority of patients they probably cannot account for the abnormalities in lymphocyte subsets. Patient neutrophils stimulated with endotoxin-treated autologous plasma showed depressed chemotactic activity and this seems to be an intrinsic cellular defect rather than plasma inhibition. Random migration of neutrophils was normal. Reduction of nitroblue tetrazolium by endotoxin- stimulated neutrophils was also decreased. These findings further document the presence of immunosuppression in human Chagas' disease. They may be relevant to autoimmunity, defense against microorganisms and against tumor cells at least in a subset of patients with more severe abnormalities.

Trypanosoma cruzi: modification of alkaline phosphatase activity induced by trypomastigotes in cultured human placental villi

Human term placental villi cultured ''in vitro" were maintained with bloodstream forms of Trypanosoma cruzi during various periods of time. Two different concentrations of the parasite were employed. Controls contained no T. cruzi. The alkaline phosphatase activity was determined in placental villi by electron microscopy and its specific activity in the culture medium by biochemical methods. Results showed that the hemoflagellate produces a significant decrease in enzyme activity as shown by both ultracytochemical and specific activity studies and this activity was lower in cultures with high doses of parasites. The above results indicate that the reduction in enzyme activity coincides with the time of penetration and proliferation of T. cruzi in mammalian cells. These changes may represent an interaction between human trophoblast and T. cruzi.

Increased natural killer activity does not prevent progression of experimental Kala-azar

Kala-azar is the visceral form of leishmaniasis and it is caused by intracellular parasites from the complex Leishmania donovani. Golden hamster (Mesocricetus auratus) infected with Leishmania donovani develop a disease very similar to human Kala-azar. There is conspicuous hipergammaglobulinaemia and their T cells do not respond to stimulation with parasite antigens. We used this experimental model to evaluate the natural killer (NK) activity during the initial phase of the disease. Outbred hamsters infected by intravenous route with 5.106 amastigotes of L. donovani 1S showed a concurrent increase in the spleen weight and in the spleen cell number. Using the single cell assay we detected a significant increase in the percentage of NK effector cells on the 4th day of infection. Imprints from spleen and liver showed at days 14 and 28 a significant increase in the parasite burden . These results show that the increased NK activity in the beginning of the infection was not able to restrain the progression of the disease in this experimental model.

Hepatitis C viral load does not predict disease outcome: going beyond numbers

The analysis of 58 patients with chronic hepatitis C without cirrhosis and treated with interferon-alpha demonstrated that hepatitis C viral (HCV) load does not correlate with the histological evolution of the disease (p = 0.6559 for architectural alterations and p = 0.6271 for the histological activity index). Therefore, the use of viral RNA quantification as an evolutive predictor or determinant of the severity of hepatitis C is incorrect and of relative value. A review of the literature provided fundamental and interdependent HCV (genotype, heterogeneity and mutants, specific proteins), host (sex, age, weight, etc) and treatment variables (dosage, time of treatment, type of interferon) within the broader context of viral kinetics, interferon-mediated immunological response (in addition to natural immunity against HCV) and the role of interferon as a modulator of fibrogenesis. Therefore, viral load implies much more than numbers and the correct interpretation of these data should consider a broader context depending on multiple factors that are more complex than the simple value obtained upon quantification.

Evaluation of the in vitro activity of six antimicrobial agents against Neisseria gonorrhoeae

Use of antimicrobials for the treatment of gonorrhea started in 1930 with the utilization of sulfonamides. With the years other drugs were used for its treatment such as penicillin, tetracycline, spectinomycin, and others. Although highly specific in the beginning, these drugs, with time did not show anymore the expected therapeutic results because of aspects of chromosomal and plasmid-mediated resistance. The purpose of this study was to evaluate the susceptibility of Neisseria gonorrhoeae strains to six drugs used for its treatment (penicillin, tetracycline, cefoxitin, thiamphenicol, spectinomycin and ofloxacin) by the determination of minimal inhibitory concentrations of these drugs. We concluded that drugs, such as cefoxitin, thiamphenicol and spectinomycin still are excellent pharmacological agents for the treatment of gonorrhea. Penicillin, although still efficient, needs more attention regarding its use, as well as ofloxacin, because of the emergence of resistant strains. Tetracycline and its derivatives should be strongly contraindicated for the treatment of gonorrhea.

The "in vitro" antifungal activity evaluation of propolis G12 ethanol extract on Cryptococcus neoformans

Cryptococcosis is a worldwide disease caused by the etiological agent Cryptococcus neoformans. It affects mainly immunocompromised humans. It is relatively rare in animals only affecting those that have received prolonged antibiotic therapy. The propolis is a resin that can present several biological properties, including antibacterial, antifungal and antiviral activities. The standard strain C. neoformans ATTC 90112 was used to the antifungal evaluation. The tests were realized with propolis ethanol extract (PEE) G12 in concentrations from 0.1 to 1.6 mg mL-1. The evaluation of MIC and MFC were done according to DUARTE (2002)5. The inhibitory effect of PEE G12 on the fungal growing was seen at the concentration of 0.2 mg mL-1 and 1.6 mg mL-1 was considered a fungicidal one.

Alterations in lipid transfer to High-Density Lipoprotein (HDL) and activity of paraoxonase-1 in HIV+ patients

HIV+ patients often develop alterations of the plasma lipids that may implicate in development of premature coronary artery disease. High-density lipoprotein (HDL) has an important role in preventing atherogenesis and the aim of this study was to investigate aspects of HDL function in HIV+ patients. HIV+ patients (n = 48) and healthy control subjects (n = 45) of both sexes with similar age were studied. Twenty-five were not being treated with antiretroviral agents, 13 were under reverse transcriptase inhibitor nucleosidic and non-nucleosidic (NRTI+NNRTI) and 10 were under NRTI + protease inhibitors (NRTI+PI) treatment. Paraoxonase 1 (PON1) activity and the transfer of free and esterified cholesterol, tryglicerides and phospholipids from a lipidic nanoemulsion to HDL were analyzed. In comparison with healthy controls, HIV+ patients presented low PON-1 activity and diminished transfer of free cholesterol and tryglicerides. In contrast, phospholipid transfer was increased in those patients, whereas the transfer of cholesteryl esters was unchanged. NRTI+NNRTI increases the transfer of cholesteryl esters and triglycerides but in NRTI+PI there was no difference in respect to non-treated HIV+ patients. HDL from HIV+ patients has smaller antioxidant properties, as shown by lower PON-1 activity, and the transfer of lipids to this lipoprotein fraction is also altered, suggesting that HDL function is defective in those patients.

Potential utility of hyperbaric oxygen therapy and propolis in enhancing the leishmanicidal activity of glucantime

In this study we investigated the efficacy of hyperbaric oxygen (HBO) therapy, alone or combined with the pentavalent antimonial glucantime on Leishmania amazonensis infection. In parallel, the effect of Brazilian red propolis gel (propain) alone or combined with glucantime on L. amazonensis infection was evaluated. The inhibition of the infection in macrophages treated with glucantime in combination with HBO exposition was greater than that of macrophages treated with glucantime alone or HBO alone. The susceptible mouse strain BALB/c infected in the shaved rump with L. amazonensis treated with glucantime and exposed to HBO showed: time points in the course of the disease in which lesions were smaller than those of mice treated with glucantime alone and revascularization of the skin in the lesion site; interferon-gamma (IFN-g) levels were not elevated in lymph node cells from these animals. Propain alone was not efficient against lesions, although less exudative lesions were observed in animals treated with propain alone or combined with glucantime. These results reveal the potential value of HBO and red propolis in combination with glucantime for treating cutaneous leishmaniasis and encourage further studies on the effect of more aggressive HBO, propolis and glucantime therapies on different mouse models of leishmaniasis.

A clinico-pathological study of 163 untreated cases of chronic hepatitis C

We performed a clinico-pathological study of 163 untreated cases of chronic hepatitis C. Eighty five percent of the patients were clinically asymptomatic and their physical examinations sbowed unremarkable or minimal changes at the time of the liver biopsy Liver function tests tended to present slight abnormalities, involving mild elevations of the activity of the aminotransferases and gamma-glutamil transferase levels. In spite of these mild abnormalities advanced chronic liver disease ivas histologically detected in eighty nine percent of the patients, mainly showing chronic active hepatitis. The most characteristic histological finding ivas an interlobular bile duct damage which correlated with the presence of tymphoid aggregates in the portal tracts and with the development of fibrosis.

In vitro differential activity of phospholipases and acid proteinases of clinical isolates of Candida

INTRODUCTION: Candida yeasts are commensals; however, if the balance of normal flora is disrupted or the immune defenses are compromised, Candida species can cause disease manifestations. Several attributes contribute to the virulence and pathogenicity of Candida, including the production of extracellular hydrolytic enzymes, particularly phospholipase and proteinase. This study aimed to investigate the in vitro activity of phospholipases and acid proteinases in clinical isolates of Candida spp. METHODS: Eighty-two isolates from hospitalized patients collected from various sites of origin were analyzed. Phospholipase production was performed in egg yolk medium and the production of proteinase was verified in a medium containing bovine serum albumin. The study was performed in triplicate. RESULTS: Fifty-six (68.3%) of isolates tested were phospholipase positive and 16 (44.4%) were positive for proteinase activity. C. tropicalis was the species with the highest number of positive isolates for phospholipase (91.7%). Statistically significant differences were observed in relation to production of phospholipases among species (p<0,0001) and among the strains from different sites of origin (p=0.014). Regarding the production of acid protease, the isolates of C. parapsilosis tested presented a larger number of producers (69.2%). Among the species analyzed, the percentage of protease producing isolates did not differ statistically (χ2=1.9 p=0.5901 (χ2=1.9 p=0.5901). CONCLUSIONS: The majority of C. non-albicans and all C. albicans isolates were great producers of hydrolytic enzymes and, consequently, might be able to cause infection under favorable conditions.