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Macrophages co-incubated with Candida albicans strain CR1 in vitro showed early signs of apoptosis, but evolved to necrosis after 2 h. In this study, we investigated whether strain CR1 caused apoptosis or necrosis of macrophages after its inoculation into mice peritoneal cavity, and whether this correlated with the secretion of IL-10. Peritoneal macrophages from mice that received an inoculum of C. albicans CR1 showed signs of apoptosis and necrosis from 30 min to 2 h afterwards, whereas heat-killed C. albicans did not cause those effects. IL-10 production was low during the first 6 h post-infection, when macrophages predominated in the peritoneal exudate, whereas its higher production after 24 h correlated with an increase of neutrophils in the exudate. Treatment of CR1 with pepstatin (an inhibitor of proteinases) prevented the process of apoptosis and significantly reduced IL-10 production, suggesting that the increased production of IL-10 was caused by processes occurring during the initial phase of infection, such as apoptosis, necrosis and uptake of death cells.

Serotonin concentration was determined in the brains of male and female rats on the 1st, 4th, 8th, and 12th day after birth. It was observed that while the amount of 5HT is comparable within the two sexes up to day 8, it rises significantly in females on day 12. This elevation in serotonin levels could be prevented if the females were injected with testosterone propionate on the day of birth. By comparison, males castrated at birth had brain serotonin levels comparable to those in intact females and significantely greater than those in intact littermates. These results suggest that the serotonin concentration may be related to the process of sexual differentiation of the brain, since this concentration is modified by the same procedures that induce androgenization. It is also suggested that the testosterone liberated by the neonatal gonad may modify the metabolism of brain serotonin only on day 12, which period corresponds to the time of the sexual differentiation of the structures that control gonadotrophin secretion.

In this study, we compared Escherichia coli isolates from chickens with avian cellulitis with those from feces of healthy chickens. Cellulitis-derived strains presented phenotypic and genotypic characteristics of greater virulence than did the fecal isolates. Phylogenetic analysis by repetitive extragenic palindromic-PCR showed that, in agreement with their virulence characteristics, the cellulitis isolates form two clonal groups distinct from the fecal isolates.Escherichia coli causes a variety of diseases in poultry, including respiratory tract infection, omphalitis, swollen-head syndrome, enteritis, septicemia, and cellulitis (3, 7), and these diseases are responsible for major economic losses in the chicken industry. Cellulitis lesions cause carcass downgrading and condemnation losses estimated at $40 million annually (7) in the United States. In Brazil, cellulitis is responsible for 45.2% of the broiler carcasses condemned for skin lesions (2), and the economic losses are estimated at $10 million annually.Some clones of E. coli may be more effective in causing cellulitis, since experimental inoculation of isolates from cellulitis lesions reproduced this disease with a significantly greater frequency (100%) than did inoculation of isolates from airsacculitis lesions (42%) or inoculation of fecal isolates (8%) (9). However, E. coli strains isolated from cellulitis lesions expressed many virulence-associated factors similar to those presented by strains isolated from other colibacillosis lesions and from feces (6, 8), which shows that the expression of these virulence factors by themselves cannot explain the differences in pathogenicity presented by these isolates.Since avian colibacillosis in its different forms occurs worldwide, we can gain a better understanding of its pathogenesis by a phylogenetic analysis of the clonal relations among E. coli isolates in several regions and in different countries. In this study, we used phenotypic and genotypic methods to examine the presence of virulence factors in E. coli isolates obtained in Southern Brazil from broiler chickens and determined by repetitive extragenic palindromic (REP)-PCR the genetic relationship among these isolates and avian fecal isolates.Fifty-two broiler chickens presenting cellulitis were collected from 52 different flocks in Southern Brazil, and from each animal one E. coli strain was isolated from pure culture and maintained by standard procedures. Twelve E. coli strains were obtained from the feces of healthy chickens. Isolates were grown on brain heart infusion agar (Difco) for 18 h at 37°C for phenotypic or genotypic analysis.The following phenotypic properties of the E. coli isolates were evaluated by standard methods (1, 9, 11): antibiotic resistance, pathogenicity to 1-day-old chickens, motility, ability to experimentally reproduce cellulitis (applied to 20 isolates), production of hemolysins, presence of K1 capsule, hemagglutination, production of aerobactin, resistance to chicken serum, and production of cytotoxins to Vero cells. All ...

Aims: The effects of medium composition, calcium, iron and oxygen tension on the haemolytic activity of Plesiomonas shigelloides were investigated. Methods and Results: The haemolytic activity of seven strains of Ple. shigelloides was tested on the surface of Luria Agar (LA), Brain Heart Infusion Agar (BHIA) and Trypitic Soy Agar (TSA) containing 5% (v/v) sheep blood, and in the Agar Overlay (AO) assay. All strains produced b-haemolysis in the AO assay in three media, and on the surface of LA. The kinetics of growth and haemolytic activity of Ple. shigelloides 9P3-1 were evaluated in six different media, and the highest production of haemolysin occurred in Luria Broth (LB). The haemolytic activity of 9P3-1 was stimulated by Ca 2+ and inhibited by EDTA. Addition of iron to the culture medium did not affect bacterial growth, although it reduced bacterial haemolytic activity. In the presence of an iron chelator, growth of the 9P3-1 was inhibited, but its haemolytic activity was enhanced. Conclusions: The haemolytic activity of Ple. shigelloides depends on medium composition, and that it is regulated by iron and is calcium-dependent. Signi®cance and Impact of the Study: These results show the importance of optimization of media composition and oxygen tension for detection of Ple. shigelloides haemolytic activity.

The mechanisms through which Candida albicans is recognized by immune cells and how it triggers host defence are not completely understood. In this study, we evaluated the effect of Concanavalin-A on the clearance of C. albicans by infected mice and their production of proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). Subgroups of 5 animals were pretreated with Con-A (250 mug mL(-1) PBS) and after 96 h were infected intraperitoneally with 10(7) cells of C. albicans CR15 (an isolate from a HIV+ person); 30 min, 2, 6, 24 or 72 h after infection the mice were sacrificed. Phagocytosis of C. albicans by peritoneal macrophages increased 30 min after infection in mice pretreated with Con-A. The liver presented the greatest number of CFUs, and this number was reduced by pretreatment with Con-A. Control animals infected with C. albicans presented a significant increase in plasmatic alanine aminotransferase, which was not observed in mice treated with Con-A. Two hours after infection the production of TNF-alpha in the liver of mice pretreated with Con-A was significantly increased. These results suggest that a single dose of Con-A caused a beneficial modulating action of the inflammatory response during infection with C. albicans.

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In a previous study, our group verified that mice pretreated with concanavalin-A (Con-A) produced more tumour necrosis factor (TNF)-alpha and presented greater Candida clearance from the peritoneal cavity, liver and spleen, which yielded a higher survival rate than control animals. In this work, the hypothesis that macrophages were of crucial importance in overcoming the infection was tested. Thus, peritoneal macrophages from mice pretreated for 3 days with Con-A or phosphate-buffered saline (PBS) were coincubated with CR1, CR15 and 577 isolates of Candida albicans for 0.5, 1 and 2 h. The ability of Con-activated macrophages to produce TNF-alpha, ingest via mannose receptors and kill all the isolates was significantly greater compared with PBS-treated macrophages, and activated macrophages exhibited a lower incidence of apoptosis, verified by binding to annexin V-fluorescein isothiocyanate. The transition of yeast cells to filamentous forms during coincubation for 2 h with control macrophages was about 73-80%, whereas in the presence of Con-A-activated macrophages, it was 35-40%. Our results suggest that a greater clearance of C. albicans infection through treatment with Con-A is probably due to the activation of macrophages, which produce more TNF-alpha, express more mannose receptors and are better endowed to kill ingested C. albicans.