Increased ompW and ompA expression and higher virulence of Acinetobacter baumannii persister cells.

BACKGROUND: Acinetobacter baumannii is one of the main causes of healthcare-associated infections that threaten public health, and carbapenems, such as meropenem, have been a therapeutic option for these infections. Therapeutic failure is mainly due to the antimicrobial resistance of A. baumannii, as well as the presence of persister cells. Persisters constitute a fraction of the bacterial population that present a transient phenotype capable of tolerating supra-lethal concentrations of antibiotics. Some proteins have been suggested to be involved in the onset and/or maintenance of this phenotype. Thus, we investigated the mRNA levels of the adeB (AdeABC efflux pump component), ompA, and ompW (outer membrane proteins) in A. baumannii cells before and after exposure to meropenem. RESULTS: We found a significant increase (p-value < 0.05) in the expression of ompA (> 5.5-fold) and ompW (> 10.5-fold) in persisters. However, adeB did not show significantly different expression levels when comparing treated and untreated cells. Therefore, we suggest that these outer membrane proteins, especially OmpW, could be part of the mechanism of A. baumannii persisters to deal with the presence of high doses of meropenem. We also observed in the Galleria mellonella larvae model that persister cells are more virulent than regular ones, as evidenced by their LD50 values. CONCLUSIONS: Taken together, these data contribute to the understanding of the phenotypic features of A. baumannii persisters and their relation to virulence, as well as highlight OmpW and OmpA as potential targets for drug development against A. baumannii persisters.

Kinetic characterization and gene expression of adenosine deaminase in intact trophozoites of Trichomonas vaginalis.

Trichomonas vaginalis is a parasite that resides in the human urogenital tract and causes trichomonosis, the most prevalent nonviral sexually transmitted disease. Nucleoside triphosphate diphosphohydrolase (NTPDase), which hydrolyzes extracellular di- and triphosphate nucleotides, and ecto-5'-nucleotidase, which hydrolyzes AMP, have been characterized in T. vaginalis. The aim of this study was to characterize the adenosine deaminase (ADA) activity in intact trophozoites of T. vaginalis. A strong inhibition in adenosine deamination was observed in the presence of calcium and magnesium, which was prevented by EDTA. The apparent K(M) value for adenosine was 1.13 ± 0.07mM. The calculated V(max) was 2.61 ± 0.054 nmol NH(3) min(-1) mg(-1) protein. Adenosine deamination was inhibited in the presence of erythro-9-(2-hydroxy-3-nonyl)adenine. Semi-quantitative reverse transcriptase-PCR experiments were performed and both ADA-related genes ada(125) and ada(231) mRNA were expressed, although ada(231) in higher quantity when compared with the ada(125) : α-tubulin ratio. Furthermore, a phylogenetic analysis showed that the T. vaginalis sequences formed a clade with Entamoeba histolytica and Dictyostelium discoideum sequences, and it strongly suggests homologous functions in the T. vaginalis genome. The presence of ADA activity in T. vaginalis may be important to modulate the adenosine/inosine levels during infection and, consequently, to maintain the anti-inflammatory properties through different nucleoside-signalling mechanisms.

Baccharis dracunculifolia, the main botanical source of Brazilian green propolis, displays antiulcer activity.

Baccharis dracunculifolia is the most important botanical source of Southeastern Brazilian propolis, known as green propolis for its colour. In a previous study, we described the gastric protective effect of the hydroalcoholic extract of Brazilian green propolis. We therefore wanted to investigate the possibility of using B. dracunculifolia extract for antiulcer treatment. This study was undertaken to evaluate the anti-ulcerogenic property of hydroalcoholic extract of B. dracunculifolia aerial parts. The HPLC analysis of the chemical composition of B. dracunculifolia extract used in this study revealed the presence mainly of cinnamic acid derivates and flavonoids. Doses of 50, 250 and 500 mg/kg of B. dracunculifolia crude extract and positive controls (omeprazole or cimetidine) significantly diminished the lesion index, the total lesion area and the percentage of lesion compared with negative control groups. The percentage of ulcer inhibition was significantly higher in groups treated with B. dracunculifolia, cimetidine or omeprazole, with all protocols used, compared with negative control groups. Regarding the model of gastric secretion, reductions in the volume of gastric juice and total acidity were observed, as well as an increase in the gastric pH. These results were similar to results from studies carried out with green propolis extract. Although more investigations are required, our results suggest that B. dracunculifolia has potential to be used as a phytotherapic preparation for the treatment of gastric ulcer.

Effect of Brazilian green propolis on experimental gastric ulcers in rats.

Propolis is a resinous hive product collected by honeybees from plants. The propolis produced in Southeastern of Brazil is known as green propolis because of its color. Modern herbalists recommend its use because it displays antibacterial, antifungal, antiviral, hepatoprotective, anti-inflammatory, immunomodulatory and anti-ulcer properties. The anti-ulcer activity of green propolis hydroalcoholic crude extract was evaluated by using models of acute gastric lesions induced by ethanol, indomethacin and stress in rats. Moreover, the effects of extract on gastric content volume, pH and total acidity, using pylorus ligated model were evaluated. Animals pretreated with propolis hydroalcoholic crude extract (50, 250 and 500 mg/kg) showed a significant reduction in lesion index, total affected area and percentage of lesion in comparison with control group (p<0.05) in the ethanol-induced ulcer model. Green propolis extract, at a higher dose (500 mg/kg), displayed a significant protection by reducing (p<0.05) the evaluated parameters in the gastric ulceration induced by indomethacin. In the stress-induced ulcer model it was observed a significant reduction (p<0.05) in those parameters in animals treated with green propolis extract (250 and 500 mg/kg). Regarding the pylorus ligated model it was observed that green propolis extract (250 and 500 mg/kg) displayed an anti-secretory activity, which lead to a reduction in the gastric juice volume, total acidity and pH. These findings indicate that Brazilian green propolis displays good anti-ulcer activity, corroborating the folk use of propolis preparations, and contributing for its pharmacological validation.