Combining ability of Phaseolus vulgaris L. for resistance to common bacterial blight

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Scanning electron microscopic study of the cleaning ability of chlorhexidine as a root-canal irrigant

Aim To evaluate in vitro the cleaning of root-canal walls after irrigation with different irrigants.Methodology A total of 36 recently extracted human teeth were divided into four experimental groups according to the irrigating solution used: saline; 2% chlorhexidine; 2.5% sodium hypochlorite; and 2.5% sodium hypochlorite + EDTA. The cleaning of the apical, middle and coronal thirds of the root canals was evaluated by scanning electron microscope examination using a 4-point scoring system.Results the best cleaning was obtained using 2.5% sodium hypochlorite and EDTA, followed by 2.5% sodium hypochlorite only (P < 0.05), whose cleaning was similar to chlorhexidine only in the cervical third. Cleaning by saline and 2% chlorhexidine was worse than the other two groups and was similar in all thirds. Better cleaning was found in the cervical and middle thirds for all groups with the worst results in the apical third.Conclusions the apical third of the root canals was not cleaned as well as the middle and coronal thirds. Cleaning by chlorhexidine and saline was inferior compared to the cleaning by sodium hypochlorite with and without EDTA.

Ability of bacteriophages isolated from different sources to reduce Salmonella enterica serovar enteritidis in vitro and in vivo

Salmonella enterica serovar Enteritidis-lysing bacteriophages isolated from poultry or human sewage sources were used to reduce Salmonella Enteritidis in vitro and in experimentally infected chicks. Cocktails of 4 different bacteriophages obtained from commercial broiler houses (CB4O) and 45 bacteriophages from a municipal wastewater treatment plant (WT45O) were evaluated. In experiment 1, an in vitro crop assay was conducted with selected bacteriophage concentrations (105 to 101 pfu/mL) to determine ability to reduce Salmonella Enteritidis in the simulated crop environment. Following 2 h at 37 degrees C, CB40 or WT45O reduced Salmonella Enteritidis recovery by 1.5 or 5 log, respectively, as compared with control. However, CB40 did not affect total SE recovery after 6 h, whereas WT45O resulted in up to a 6-log reduction of Salmonella Enteritidis. In experiment 2, day-of-hatch chicks were challenged orally with 3 x 103 cfu /chick Salmonella Enteritidis and treated cloacally with 1 X 109 WT45O pfu/chick I h postchallenge. One hour later, chicks were treated or not with a commercially available probiotic (Floramax-B11). Both treatments significantly reduced Salmonella Enteritidis recovery from cecal tonsils at 24 h following vent lip application as compared with controls, but no additive effect was observed with the combination of bacteriophages and probiotic. In experiment 3, day-of-hatch chicks were challenged orally with 9 x 103 cfu/chick Salmonella Enteritidis and treated via oral gavage with I X 108 CB40 pfu/chick, 1.2 x 108 WT45O pfu/chick, or a combination of both, I h postchallenge. All treatments significantly reduced Salmonella Enteritidis recovered from cecal tonsils at 24 h as compared with untreated controls, but no significant differences were observed at 48 h following treatment. These data suggest that some bacteriophages can be efficacious in reducing SE colonization in poultry during a short period, but with the bacteriophages and methods presently tested, persistent reductions were not observed.

Pressure evaluation of the antireflux ability of the rat ureterovesical junction

The bladder pressure necessary to cause vesicoureteral reflux (VUR) was measured in 16 female rats. Under general anesthesia, the ureters were exposed via an abdominal incission and a pressure catheter was placed near the uterovesical junction. Values of bladder distension and bladder pressure increase to cause VUR were obtained by injecting isotonic saline in one ureter until VUR in the opposite ureter was detected as a sudden pressure increase. After 5 min the same procedure was done on the contralateral side. This procedure was repeated eight times in each rat with a 15-min intermission. The bladder pressure at which VUR occurred was measured through a uretral catheter. Two groups were studied: G1, control, and G2, administration of intravenous metoclopramide (0.007 mg/100 g body weight) four times.

Metacyclogenesis modulates the ability of Leishmania promastigotes to induce IL-12 production in human mononuclear cells

Immunity against the intracellular protozoan Leishmania species is highly dependent on Th1 development. We have previously shown that IL-12 is a powerful and probably obligatory factor for Th1 cell generation and proliferation. We also observed that the experimental infection of C3H and BALB/c mice with Leishmania major is associated with IL-12 production in vivo. Now we demonstrate that metacyclic L. major promastigotes are poor inducers of IL-12 in vitro in fresh human PBMC and monocytes. In addition, we show that the ability of this pathogen to induce IL-12 and other cytokines is modulated by the metacyclogenic process, which had previously not been recognized. In contrast to the infective parasites (metacyclic promastigotes), the procyclic promastigotes collected at the logarithmic phase of the culture displayed a striking ability to induce IL-12, IFN-γ, TNF-α, and IL-10. Despite this differential effect of procyclic and metacyclic parasites in terms of IL-12 induction, both stages were inhibitory for IL-12 production induced by Staphylococcus aureus. The ability of procyclic promastigotes and, to a much lesser extent, that of metacyclic promastigotes to induce IL-12 were enhanced by pretreatment of monocytes in a cytokine milieu containing IFN-γ, IL-4, IL-13, or granulocyte-macrophage CSF or. by neutralization of endogenous IL-10. Our results suggest the development of an evasion mechanism as the Leishmania promastigotes mature to infectious forms and the possi-bility of using Ags derived from procyclic promastigotes for immunization procedures. Copyright © 1997 by The American Association of Immunologists.

Diffusion ability of endotoxin through dentinal tubules

The aim of this study was to evaluate the ability of endotoxin to diffuse through dentinal tubules towards the cement and to observe the period of time needed for it to reach the external root surface. Thirty single-rooted human teeth had their crowns and apices removed in order to standardize the root length to 15 mm. Teeth were instrumented until #30 K-file and made externally impermeable with epoxy adhesive, leaving 10 mm of the exposed root (middle third). The specimens were placed in plastic vials and irradiated (60Co gamma-rays). Then, they were divided into 2 groups (n = 15): G1) Escherichia coli endotoxin was inoculated into the root canal of the specimens and 1 ml of pyrogen-free water was put in the tubes; G2) (control): pyrogen-free water was inoculated into the root canals and 1 ml of pyrogen-free water was put in each tube. After 30 min, 2 h, 6 h, 12 h, 24 h, 48 h, 72 h and 7 days, the water of the tubes was removed and replaced. The removed aliquot was tested for the presence of endotoxin. Considering that the endotoxin is a B-lymphocyte polyclonal activator, at each experimental period, B-lymphocyte culture was stimulated with a sample of water removed from each tube and antibody (IgM) production was detected by ELISA technique. The results of IgM production were higher in groups of 24 h, 48 h, 72 h and 7 days in relation to the other studied groups, with statistically significant differences (ANOVA and Tukey's test p < 0.05). Endotoxin was able to diffuse through the dentinal tubules towards the cement, reaching the external root surface after the period of 24 h.

Effect of different dye solutions on the evaluation of the sealing ability of Mineral Trioxide Aggregate.

Alkaline materials have shown incompatibility with methylene blue dye in leakage experiments. The goal of the present study was to analyze the effect of different dyes on the evaluation of the apical sealing ability of Mineral Trioxide Aggregate root-end fillings. Fifty-six extracted human canines were submitted to root canal instrumentation and obturation. After apical resection, retrograde cavities were prepared and teeth were randomly divided into four experimental (n = 13) and two control groups (n = 2). The following root-end filling materials were used: groups 1 and 2--Pro Root MTA (Dentsply), groups 3 and 4--zinc oxide-eugenol cement (ZOE). Teeth in groups 1 and 3 were immersed in 2% methylene blue solution, while teeth in groups 2 and 4 were immersed in 0.2% rhodamine B in a reduced pressure environment for 48 hours. Teeth were then longitudinally sectioned and leakage was evaluated. Results were submitted to statistical analysis (ANOVA and Tukey's test). Group 1 presented the least leakage (p < 0.05). It was concluded that the evaluation of the sealing ability of MTA is influenced by the dye used, since this material presented better sealing ability when evaluated with Methylene Blue, but was similar to ZOE when evaluated with rhodamine B.