Extracellular <Emphasis Type="Italic">Paracoccidioides brasiliensis</Emphasis> phospholipase B involvement in alveolar macrophage interaction

Background  

Phospholipase B (PLB) has been reported to be one of the virulence factors for human pathogenic fungi and has also been described as necessary for the early events in infection. Based on these data, we investigated the role of PLB in virulence and modulation of the alveolar pulmonary immune response during infection using an in-vitro model of host-pathogen interaction, i.e. Paracoccidioides brasiliensis yeast cells infecting alveolar macrophage (MH-S) cells.     

Geldanamycin promotes nuclear localisation and clearance of PHOX2B misfolded proteins containing polyalanine expansions

Polyalanine expansions in the PHOX2B gene have been detected in the vast majority of patients affected with congenital central hypoventilation syndrome, a neurocristopathy characterized by absence of adequate control of breathing, especially during sleep, with decreased sensitivity to hypoxia and hypercapnia. The correlation between length of the alanine expanded tracts and severity of congenital central hypoventilation syndrome respiratory phenotype has been confirmed by length-dependent cytoplasmic PHOX2B retention with formation of aggregates. To deepen into the molecular mechanisms mediating the effects of PHOX2B polyalanine expansions, we have set up experiments aimed at assessing the fate of cells characterized by PHOX2B polyalanine aggregates. In particular, we have observed that activation of the heat shock response by the drug geldanamycin is efficient both in preventing formation and in inducing clearance of PHOX2B pre-formed polyalanine aggregates in COS-7 cells expressing PHOX2B-GFP fused proteins, and ultimately also in rescuing the PHOX2B ability to transactivate the Dopamine-beta-Hydroxilase promoter. In addition, we have demonstrated elimination of PHOX2B mutant proteins by the proteasome and autophagy, two cellular mechanisms already been involved in the clearance of proteins containing expanded polyglutamine and polyalanine tracts. Moreover, our data suggest that geldanamycin effects on PHOX2B aggregates may be also mediated by the proteasome pathway. Finally, analysis of cellular toxicity due to polyalanine aggregates has confirmed the occurrence of cell apoptosis consequent to expression of PHOX2B carrying the longest expanded alanine tract and shown that geldanamycin can delay cell progression toward the most advanced apoptotic stages.     

Risk assessment for inherited susceptibility to cancer: a review of the psychosocial and ethical dimensions

The objective of this study was to conduct a broad-based systematic review of social, ethical, and legal considerations associated with genetic cancer risk assessment technologies (CaRATs). This paper focuses on psychosocial and ethical issues. Search results were limited to papers published in English, French, or German from January, 1990, to May, 2003. A quality assessment tool was developed and applied to retrieved papers. Application of the quality assessment tool resulted in 77 of 247 qualitative and quantitative primary research papers being reviewed and synthesized. A broad range of issues were addressed and grouped into content areas. Despite a large literature addressing psychosocial and ethical issues associated with CaRATs, many existing studies are not adequate to inform decision-makers and stakeholders. Careful policy analysis, as in some of the economic analyses reviewed here, is important to bridge this gap.     

Inhibition of Nitric Oxide Production by Macrophages in Chromoblastomycosis: A Role for Fonsecaea pedrosoi Melanin

Chromoblastomycosis is a chronic and progressive deep mycosis that is usually found in tropical and subtropical areas. Fonsecaea pedrosoi is considered its most frequent etiologic agent and causes a typical granulomatous inflammatory response, whose degree reflects the immune status of the host. Since macrophages play a fundamental role in the control of the infection, this study aimed at investigating the production of oxygen reactive specimens, the phagocytic capacity and the production of nitric oxide (NO) by macrophages employing in vitro assays and an in vivo model of chromoblastomycosis. Our results demonstrated that, during the infection, peritoneal macrophages show an increased phagocytic capacity and H₂O₂ production, but also a reduced ability to produce NO. Moreover, F. pedrosoi stimulated H₂O₂ production in vitro but not the synthesis of NO. The incubation of IFNγ and LPS-stimulated macrophages with melanin, obtained from the fungus, inhibited NO production. Examination of the liver and spleen of infected animals, at day 30 or 60 following inoculation, showed a progressive increase in the number and size of granulomas, indicating that macrophages are properly mobilized and activated. Our data suggest that the inability of the host to clear F. pedrosoi, leading to a chronic disease, is due, at least in part, to the inhibition of NO synthesis by macrophages by fungus-produced melanin.     

The dynamics of forest tent caterpillar outbreaks across east‐central Canada

An analysis of forest tent caterpillar Malacosoma disstria defoliation records from Ontario and Quebec over the period 1938–2002 indicates that outbreaks recur periodically and somewhat synchronously among regions of the two provinces. Cluster analysis revealed that the most strongly periodic, large‐scale, synchronized fluctuations occurred within three regions: northwestern Ontario, eastern Ontario/western Quebec and southeastern Quebec. Defoliation in the vast surrounding hinterlands tended to be infrequent and sporadic, loosely tracking defoliation in the core outbreak regions. One small cluster in northeastern Ontario stood out as anomalous, as a result of an increasing trend in the duration of periodic defoliation episodes, marked by an unprecedented double‐wave of defoliation that persisted from 1992 to 1999. This is the precise area where, in the early 2000s, trembling aspen Populus tremuloides stems were mapped as being in a state of decline of unprecedented severity and extent. Our results suggest forest tent caterpillar has the potential to cause significant impacts on forest health and, hence, carbon budgets in east‐central Canada and that the forest tent caterpillar deserves more attention as a model system of forest insect disturbance ecology.     

Molecular Mechanisms Endowing Cross-resistance to ALS-Inhibiting Herbicides in Amaranthus hybridus from Argentina

Amaranthus hybridus L. is one of the most problematic weeds in summer crops in Argentina. However, 20 years after the detection of the first case of resistance to ALS-inhibiting herbicides in this country, no extensive reports of the molecular mechanisms endowing resistance were published. In this work, we sequenced the acetolactate synthase gene of resistant plants belonging to five different populations of A. hybridus from Santa Fe and Cordoba provinces. We found that every population presented at least one of the previously documented substitutions W574L and D376E in ALS amino acid sequence. These results explain the cross-resistance to ALS-inhibiting herbicides and should alert about the usage of herbicides with a different site of action after an ineffective control of this species. This is the first report of these target-site mechanisms endowing resistance to ALS-inhibiting herbicides in A. hybridus populations from Argentina.

     

Cytologic and cytometric analysis of oral mucosa in Alzheimer's disease

OBJECTIVE: To analyze cytomorphologically the buccal mucosa of patients with Alzheimer's disease (AD). STUDY DESIGN: Brush biopsies were obtained from 10 patients with AD and 9 age-matched controls without neurologic symptoms from 3 distinct oral sites. RESULTS: A significant reduction in partially keratinized intermediate (red) cells was observed in the buccal mucosa of the AD group. In the AD group, parabasal cells from the floor of the mouth (p = 0.017) and buccal mucosa (p = 0.058) and red cells,from the tongue dorsum (p = 0.013) and buccal mucosa (p = 0.002), exhibited significantly greater nuclear areas. With regard to the nuclear to cytoplasmic (N:C) ratio, intermediate (red) cells from the buccal mucosa and tongue dorsum of AD individuals showed a decrease in this parameter (p <0.0001), while superficial (yellow) cells (from buccal mucosa) (p= 0.042) and parabasal (blue) cells (from the tongue dorsum) (p = 0.003) exhibited an increased N:C ratio. No significant differences were detected in the cells from the floor of the mouth. CONCLUSIONS: Our findings indicate that cytologic and cytometric changes were detectable in the exfoliative cytology of the buccal mucosa and tongue in the AD group.