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By Maria do Céu Silva, Jorge Gaspar1, Isabel Duarte Silva1, Daniela Leão and José Rueff

Hydroquinone occurs naturally in bacteria and plants and it is also manufactured for commercial use. Human exposure to this compound can occur by environmental, occupational, dietary and cigarette smoke exposure and from exposure to benzene, which can be metabolized to this compound. However, the main source of exposure to this compound is dietary, since hydroquinone is a naturally occurring compound in many foods. Hydroquinone can be metabolized to benzoquinones, which are potent haematotoxic, genotoxic and carcinogenic compounds that can also induce the formation of radical species, predisposing cells to oxidative damage. In order to clarify the involvement of radical species in the genotoxicity of hydroquinone, the induction of chromosomal aberrations in V79 cells was studied along with the assessment of the production of hydroxyl radicals at different pH values (6.0, 7.4 and 8.0), as well as the effect of antioxidant enzymes [catalase and superoxide dismutase (SOD)] on the clastogenic effect of hydroquinone. The results obtained indicate that the clastogenic activity of hydroquinone is dependent on the pH, suggesting that deprotonation is a fundamental step leading to DNA lesions under the experimental conditions used. The addition of S9 mix, SOD or SOD and catalase signi®cantly decreased the clastogenic activity, suggesting the involvement of superoxide anion and hydrogen peroxide in the genotoxicity of hydroquinone. However, other species generated in the auto-oxidation process of hydroquinone, such as the semiquinone radical or the quinone, also seem to play a role in its genotoxicity, since the addition of antioxidant enzymes (catalase and SOD) or S9 mix do not lead to a complete abolition of the observed genotoxic activity. These results suggest the existence of at least two mechanisms associated with the genotoxic activity of this compound.

By Cristiana Paulo; Cristina Mourão; Pedro M. Veiga; Joana M. Marques; Graça Rocha; Ana F. Alves; Amparo Querol; António A. Meliço-Silvestre; Isabel Gonçalves; Orfeu Flores; Carla Clemente; Teresa Gonçalves

We conducted a four-year (2003-2006) retrospective study of yeasts recovered in a hospital laboratory in the centre of Portugal to evaluate the epidemiology of yeast infections. Clinical isolates and data were gathered from 751 patients corresponding to 906 episodes of yeast infection. The isolates were first identified using classical and commercial methods, routinely employed at the hospital laboratory.
We then re-identified the same isolates using RFLP of the ITS 5.8S rRNA gene and sequence of the D1/D2 domain of the 26S rRNA gene. Candida parapsilosis isolates were re-identified using the Ban I digestion of the SADH gene. C. albicans was the most frequently isolated of the yeasts found in the analysed specimens, with an overall incidence of 69.6% and then in deceasing order, C. glabrata, C. tropicalis, C. parapsilosis and C. krusei. C. parapsilosis was most frequently recovered from younger patients, decreasing with age, while C. glabrata occurrence increased with age. We found an increased number of cases of fungemia per 100,000 people per year, reaching a maximum of 4.4 during 2006.

Keywords Yeast infections, molecular yeast identification, risk factor, Candida metapsilosis, Candida orthopsilosis

By S. Lucas, M. da Luz Martins, Orfeu Flores, W. Meyer, I. Spencer-Martins and J. Inácio

Abstract

Members of the Cryptococcus species complex (C. neoformans and C. gattii) are opportunistic pathogens responsible for frequently fatal cases of meningoencephalitis. These yeasts have been classified into five serotypes. Serotypes A andDare assigned to C. neoformans var. grubii and C. neoformans var. neoformans, respectively, Serotype AD strains are hybrids and serotype B and C strains are considered to belong to the related but distinct species C. gattii. Previous studies have identified ‘serotype-associated’ alleles of several genes in the Cryptococcus species complex. We developed a loop-mediated isothermal DNA amplification method using CAP59 allele- specific primers to identify the serotypes A, D and B/C of the Cryptococcus species complex.

Keywords: Cryptococcus gattii, Cryptococcus neoformans, loopmediated isothermal DNA amplification