Effects of long-term administration of Senna occidentalis seeds in the large bowel of rats

Plants of the genus Senna that contain anthranoides derivatives are frequently used as cathartics. Radiological studies have demonstrated that patients with chronic constipation who have used stimulant laxative have colonic redundancy and dilatation more frequently than patients who have not. The objective of the present work was to study morphological and histochemical changes of the lower gut after administration of Senna occidentalis seeds for a long period to rats, as observed in skeletal muscle fibers. Fragments of the lower gut of young and adult rats treated with S. occidentalis seeds (2% for 171 days and 3% for 61 days in the diet) were submitted to histological and histochemical analysis and to densitometry. The most important finding was decreased oxidative enzyme activity in smooth muscle cells and in myenteric neurons of the large bowel. As oxidative metabolism is essential for ATP and energy production, these results suggest that the functional intestinal disturbance caused by the chronic use of Senna occidentalis as a laxative can be due to a metabolic effect involving energy production, which would decrease colonic motility and cause functional colonic dilatation, but without any irreversible anatomic change.     

Tryptophan availability selectively limits NO-synthase induction in macrophages

We studied the effects of tryptophan (TRP) availability on the synthesis and release of nitric oxide (NO) and tumor necrosis factor alpha (TNF-alpha) in interferon-gamma (IFN-gamma)-activated murine macrophages of the BAC1.2F5 cell line. IFN-gamma (100 U/ml) not only increased the synthesis and release of NO and TNF-alpha from these cells but also induced indoleamine-2,3-dioxygenase, the rate-limiting enzyme of TRP catabolism. This led to an increased metabolic flow through the kynurenine pathway and significantly decreased TRP levels in macrophage incubation media. Low TRP concentrations in the media, however, modified IFN-gamma effects. In TRP-"starved" cultures, in fact, the IFN-gamma-mediated NO synthase induction was significantly reduced, and the increased TNF-alpha synthesis and release were not affected. Our results suggest that a reduced local TRP availability may modify macrophage function and possibly the outcome of immune responses.     

Correlation of c-erbB-2 and S-100 expression with the malignancy grading and anatomical site in oral squamous cell carcinoma

An immunohistochemical analysis of 32 cases of oral squamous cell carcinoma (eight in the inferior lip, eight in the lateral angle of the tongue, eight in the palate and eight in the mouth floor) was performed to evaluate the expression pattern of c-erbB-2 protein and S-100-positive cells in the lesions. The immunohistochemical expression was correlated with the tumour anatomical site and histological grading of malignancy. A higher frequency of c-erbB-2-positive cases was found in the tongue, even though no correlation could be detected between the protein expression and the tumour histological grading. With respect to the S-100-positive cells, it was observed that a quantitative decrease was present in the cases classified as high-grade tumours when compared to the low ones (P = 0.0007). Thus, c-erbB-2 immunohistochemical expression is correlated with anatomical localization, and the expression of the S-100 Langerhans' cell markers is decreased significantly in high-grade carcinomas.     

Beauveria bassiana isolated from engorged females and tested against eggs and larvae of Boophilus microplus (Acari: Ixodidae)

The purpose of this work was to evaluate the in vitro virulence of three isolates of Beauveria bassiana to eggs and larvae of the tick Boophilus microplus. The fungus tested were isolated from engorged females of B. microplus collected on the field, and identified as Bb28, Bb29 and Bb30. These isolates were evaluated by immersion of eggs and larvae in suspensions with different conidial concentrations: 10(8), 10(7), 10(6) and 10(5) conidia/ml and compared to the control groups. In the treated eggs, there was a percentage much smaller of hatching than that observed in the controls. The egg hatch was inversely proportional to the conidial concentration. In larval bioassays, all isolates resulted in a higher mortality of larvae compared to the control according to the conidial concentrations/ml, 10 days after treatment inoculation.     

Plasmodium falciparum histidine-rich protein II binds to actin,phosphatidylinositol 4,5-bisphosphate and erythrocyte ghosts in a pH-dependent manner and undergoes coil-to-helix transitions in anionic micelles

The recombinant histidine-rich protein II (HRPII) from Plasmodium falciparum was shown to bind actin and phosphatidylinositol 4,5-bisphosphate (PIP(2)) in vitro in a pH-dependent manner, very similar to hisactophilin, an actin-binding protein from ameba. Binding of HRPII to actin and PIP(2) occurred at pH 6.0 and 6.5, but not above pH 7.0. Circular dichroism (CD) spectroscopy confirmed that HRPII interacts with actin at pH below 7.0, as judged by the changes induced in the secondary structure of the HRPII/actin mixture. Further CD analysis demonstrated that HRPII adopts a predominantly alpha-helical conformation with anionic micelles of PIP(2) and SDS, but not with neutral micelles of phosphatidylcholine (PC), a feature that is common to many actin-binding proteins involved in cytoskeleton remodeling. Similarly to hisactophilin, a GFP-HRPII fusion protein shuttled from the cytoplasm to the nucleus of HeLa cells as the cellular pH was lowered from 8.0 to 6.0. HeLa cells transfected with the HRPII gene showed increased levels of histidine-rich proteins (HRPs) in the soluble cell fraction at pH 8.0. At pH 6.0, however, HRPs were detected mainly in the insoluble cell fraction. Interestingly, we found that HRPII binds to human erythrocyte membranes at pH 6.0 and 6.5 but not at pH above 7.0. Our results point to remarkable similarities between HRPII, hisactophilin, and actin-binding proteins. Possible roles of the HRPII during Plasmodium infection are discussed in the light of these findings.     

Comparison of the effectiveness of bacterial culture, 16S rDNA directed polymerase chain reaction, and checkerboard DNA-dNA hybridization for detection of Fusobacterium nucleatum in endodontic infections

Fusobacterium nucleatum is a Gram-negative, non-spore-forming, nonmotile, obligatory anaerobic rod that is normally isolated from the oral cavity. Epidemiological studies have shown that this species is one of the most prevalent in primary root canal infections. The purpose of this study was to compare the effectiveness of bacteriological culture, 16S rDNA directed polymerase chain reaction and checkerboard DNA-DNA hybridization for detection of F. nucleatum strains in infected teeth associated with periradicular lesions. Thirteen single-root teeth from adult patients, all having carious lesions, necrotic pulps, and radiographic evidence of periradicular bone loss were included in this study. Combining all methods, the results indicated that F. nucleatum was present in approximately 31% (4 of 13) of the specimens. Incidence of F. nucleatum in root canal infections, as evaluated in this study by polymerase chain reaction, culture, and DNA-DNA hybridization, was 15.4%, 15.4%, and 10.0%, respectively. Our data demonstrated that no method used herein could be considered superior for detecting F. nucleatum directly from clinical samples. However, the small number of samples examined and the low prevalence that was observed should be considered.