Essential oils of Origanum vulgare L. subsp glandulosum (Desf.) letswaart from Tunisia: chemical composition and antioxidant activity

BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) letswaart collected from three localities of north Tunisia - Krib, Bargou and Nefza - were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin-Ciocalteu method, and antioxidant effectiveness, using the 2,2-diphenyl-1-picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p-cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), gamma-terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC50, ranged from 59 to 80 mg L-1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg(-1) dry weight, varied from 9.37 to 17.70 g kg(-1) dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p-cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated.

O síndrome do silêncio: síndrome de Waardenbrug

Síndrome de Waardenburg - Perda de audição: neurossensorial, uni ou bilateral; possibilidade de existir micrótia ou apêndices pré-auriculares; nariz achatado – alargamento da pirâmide nasal; alterações na pigmentação de pele, cabelo e olhos.

Atenção conjunta em crianças surdas: especificidades do desenvolvimento e implicações para as práticas

Pretendemos neste trabalho abordar o desenvolvimento da atenção conjunta no contexto de interacções entre a criança e seus cuidadores pela importância que lhe é atribuída para o desenvolvimento sóciocognitivo e, em particular, o desenvolvimento da linguagem. O interesse por este tema advém também do relativo atraso que a investigação reporta no caso de crianças surdas filhas de pais ouvintes que se associa ao designado fenómeno de atenção dividida (Gallaway, 1998; Lederberg, 1993; Wood, Wood Griffiths, & Howarth, 1986). Por causa deste fenómeno, as crianças surdas têm de aprender a coordenar a sua atenção em relação à pessoa com quem interagem, bem como em relação a objecto ou eventos no seu ambiente. Pelas potenciais implicações para as práticas, analisaremos as estratégias de interacção usadas por mães surdas que, com mais facilidade do que mães ouvintes, andaimam o desenvolvimento das capacidades de coordenação da atenção visual das crianças e facilitam a ocorrência de episódios de atenção conjunta e a influencia que os resultados destas investigações têm tido em programas de intervenção precoce direccionados para o apoio a crianças surdas e suas famílias.

Genotoxic effects in occupational exposure to formaldehyde: A study in anatomy and pathology laboratories and formaldehyde-resins production

Background - According to the Report on Carcinogens, formaldehyde ranks 25th in the overall U.S. chemical production, with more than 5 million tons produced each year. Given its economic importance and widespread use, many people are exposed to formaldehyde environmentally and/or occupationally. Presently, the International Agency for Research on Cancer classifies formaldehyde as carcinogenic to humans (Group 1), based on sufficient evidence in humans and in experimental animals. Manyfold in vitro studies clearly indicated that formaldehyde can induce genotoxic effects in proliferating cultured mammalian cells. Furthermore, some in vivo studies have found changes in epithelial cells and in peripheral blood lymphocytes related to formaldehyde exposure. Methods - A study was carried out in Portugal, using 80 workers occupationally exposed to formaldehyde vapours: 30 workers from formaldehyde and formaldehyde-based resins production factory and 50 from 10 pathology and anatomy laboratories. A control group of 85 non-exposed subjects was considered. Exposure assessment was performed by applying simultaneously two techniques of air monitoring: NIOSH Method 2541 and Photo Ionization Detection equipment with simultaneously video recording. Evaluation of genotoxic effects was performed by application of micronucleus test in exfoliated epithelial cells from buccal mucosa and peripheral blood lymphocytes. Results - Time-weighted average concentrations not exceeded the reference value (0.75 ppm) in the two occupational settings studied. Ceiling concentrations, on the other hand, were higher than reference value (0.3 ppm) in both. The frequency of micronucleus in peripheral blood lymphocytes and in epithelial cells was significantly higher in both exposed groups than in the control group (p < 0.001). Moreover, the frequency of micronucleus in peripheral blood lymphocytes was significantly higher in the laboratories group than in the factory workers (p < 0.05). A moderate positive correlation was found between duration of occupational exposure to formaldehyde (years of exposure) and micronucleus frequency in peripheral blood lymphocytes (r = 0.401; p < 0.001) and in epithelial cells (r = 0.209; p < 0.01). Conclusions - The population studied is exposed to high peak concentrations of formaldehyde with a long-term exposure. These two aspects, cumulatively, can be the cause of the observed genotoxic endpoint effects. The association of these cytogenetic effects with formaldehyde exposure gives important information to risk assessment process and may also be used to assess health risks for exposed workers.