Revisiting the metallothionein genes polymorphisms and the risk of oral squamous cell carcinoma in a Brazilian population.

BACKGROUND: Metallothioneins (MTs) gene polymorphisms have been associated with the ability of free radical scavenging and detoxification of heavy metals leading to cancer development. Our aim was to revisit, in a Brazilian population, single-nucleotide polymorphisms (SNPs) of the MT gene family previously associated with oral squamous cell carcinoma (OSCC). MATERIAL AND METHODS: A case-control investigation with 28 OSCC patients and 45 controls was conducted, using conventional risk factors (tobacco use and alcohol consumption) as covariates. SNPs genotyping for rs8052334 (MT1B), rs964372 (MT1B), and rs1610216 (MT2A) was performed by PCR-RFLP, and SNPs for rs11076161 (MT1A) were analyzed by TaqMan assay. RESULTS: The only SNP associated with increased risk for OSCC was the MT-1A AA genotype (OR = 4.7; p = 0.01). We have also evidenced for the first time a significant linkage disequilibrium between the SNPs of MT-2A and MT-1A in this population with the highest frequency (30%) of the unfavorable haplotype G/A/C/T (rs1610216 / rs11076161 / rs964372 / rs8052334) of MT gene polymorphisms (OR = 6.2; p = 0.04). Interestingly, after removing the effects of conventional risk factors, we have uncovered the significance of the AA genotype of the rs11076161 with increased odds of 19-fold higher towards OSCC development. CONCLUSIONS: This is the first demonstration that a significant linkage disequilibrium among gene polymorphisms of the MT family may affect susceptibility to oral cancer, which is conditioned by the G/A/C/T haplotype (rs1610216/rs11076161/rs964372/ rs8052334) and the MT-1A gene polymorphism has a potential clinical utility for the OSCC risk assessment.

Cerium, manganese and cobalt oxides as catalysts for the ozonation of selected organic compounds.

Several metal oxides, as well as metal oxides supported on activated carbon, were assessed as ozonation catalysts for the removal of selected organic compounds. Two transition metals (Mn, Co) and one rare earth element (Ce) were chosen for the preparation of the two series of catalysts. These materials were used in the ozonation of two aromatic compounds (aniline and sulfanilic acid) and one textile azo dye (CI Acid Blue 113). The results were compared with those obtained with non-catalytic ozonation. All the tested materials were found to be effective ozonation catalysts. Among the metal oxides, those containing mixtures of cerium and manganese or cerium and cobalt enabled the highest mineralisation degrees. After 120 min of reaction the TOC removal achieved with Ce-Mn-O was 63% for sulfanilic acid and 67% for aniline, while Ce-Co-O allowed TOC removals of 58 and 66%, respectively. With single ozonation, the mineralisation of sulfanilic acid and aniline solutions was 34% and 40% after identical reaction period. Regarding the metal oxides supported on activated carbon, cerium and manganese oxides were, in general, the most active for the degradation of the studied compounds.

Decolourisation of dye solutions by oxidation with H(2)O(2) in the presence of modified activated carbons.

The decolourisation of dye solutions by oxidation with H(2)O(2), using activated carbon as catalyst, is studied. For this purpose, three different samples, mainly differing in the respective surface chemistries, were prepared and characterized. Moreover, this work involved three pH levels, corresponding to acid, neutral and alkaline solutions, and six dyes belonging to several classes. The catalytic decolourisation tests were performed in a laboratorial batch reactor. Adsorption on activated carbon and non-catalytic peroxidation kinetic experiments were also carried out in the same reactor, in order to compare the efficiencies of the three processes. The non-catalytic reaction is usually inefficient and, typically, adsorption presents a low level of decolourisation. In these cases, the combination of activated carbon with hydrogen peroxide may significantly enhance the process, since the activated carbon catalyses the decomposition of H(2)O(2) into hydroxyl radicals, which are very reactive. Based on the experiments with the different activated carbon samples, which have similar physical properties, it is proved that the surface chemistry of the catalyst plays a key role, being the basic sample the most active. This is discussed considering the involvement of the free electrons on the graphene basal planes of activated carbon as active centres for the catalytic reaction. Additionally, it is shown that the decolourisation is enhanced at high pH values, and a possible explanation for this observation, based on the proposed mechanism, is given.

Human papillomavirus prevalence and predictors for cervical cancer among high-risk women from Rio de Janeiro, Brazil.

We assess the prevalence of human papillomavirus (HPV) and cofactors for cervical severe disease, as contribution for vaccine strategies at the right moment in which Brazilian health authorities have approved an anti-HPV vaccine. A case-control study was undertaken with 201 women who attended a public health service with previous abnormal cytology. The HPV status was ascertained by consensus primers My09/11 and typed by 6, 11, 16, 18, 31, 33, 35, and 58 specific primers. Patients diagnosed with high-grade squamous intraepithelial lesions (HSIL) and cervical cancer were referred as cases (n = 84). Patients with normal/inflammatory cervix or carrying benign cervical lesions were included in controls (n = 117). The overall prevalence of HPV infection was 75.6%, with 91.7% among cases. In spite of HPV 16 being the most frequent type (53.3%), 27.6% of infections were attributed to nonvaccine types. High-risk HPV were strongly associated to older women (OR = 6.7). Otherwise, age at the first intercourse (OR = 7.10), three or more parities (OR = 3.05), abortion episodes (OR = 4.80), and smoking (OR = 3.83) conferred a heavy effect in younger women. Among mediators affecting the progress from HSIL to cancer, age played the main role in easing the progression (OR = 1.09, P = 0.002) followed by education level (OR = 4.20, P = 0.066). White ethnia showed to be a protective factor (OR = 0.32, P = 0.055). Predictors from HPV exposure to malignant disease include demographic and behavioral factors. Public policies such as improvement of education and continued prevention campaigns might contribute to reduce this picture. This work also gives background, in identifying a target population, for implementing future vaccine strategies.

Ozonation of aniline promoted by activated carbon.

The removal of aniline from aqueous solutions by simultaneous use of ozone and activated carbon was investigated at different solution pH. For comparative purposes, single ozonation and adsorption on activated carbon were carried out in the same experimental set-up. In order to evaluate the role of the activated carbon surface chemistry during ozonation, a commercial activated carbon, Norit GAC 1240 PLUS, was submitted to oxidation in the liquid phase with HNO(3). The texture and surface chemistry of the activated carbon samples were characterized. During ozonation, complete conversion of aniline was achieved after approximately 20 min, regardless of the presence of activated carbon. In all cases, several by-products were formed during ozonation. Nitrobenzene, o- and p-aminophenol were the primary aromatic oxidation by-products identified. In terms of TOC removal, best results were achieved by the simultaneous use of ozone and activated carbon. Though there is a strong contribution of adsorption, a considerable synergetic effect between ozone and activated carbon is observed. In general, activated carbon promotes the reaction of ozonation enhancing the efficiency of this treatment process. The basic activated carbon presented greater activity in this process leading to higher mineralization rates.

Adsorption of a reactive dye on chemically modified activated carbons--influence of pH.

The surface chemistry of a commercial activated carbon with a slightly basic nature was modified by appropriate treatments in order to obtain two additional samples, respectively with acidic and basic properties, without changing its textural parameters significantly. Different techniques (N2 adsorption at 77 K, temperature programmed desorption, and determination of acidity, basicity, and pH at the point of zero charge) were used to characterize the adsorbents. Kinetic and equilibrium adsorption data of a selected textile reactive dye (Rifafix Red 3BN, C.I. reactive red 241) on the mentioned materials were obtained at the pH values of 2, 7, and 12. The kinetic curves are fitted using the second-order model. The respective rate constants seem to diminish progressively with the initial concentration for the more diluted solutions tested, reaching a constant value at higher concentrations, which depends on the experimental system under consideration (adsorbent and pH). In general, the Langmuir model provides the best fit for the equilibrium data. The different uptakes obtained are discussed in relation to the surface chemical properties of the adsorbents. It is shown that the adsorption of the reactive (anionic) dye on the basic sample (prepared by thermal treatment under H2 flow at 700 degrees C) is favored. This conclusion is explained on the basis of the dispersive and electrostatic interactions involved. Moreover, it is also shown that the optimal adsorption condition for all the activated carbons tested corresponds to solution pH values not higher than the pH(pzc) of the adsorbents, which may be interpreted by taking into account the electrostatic forces present.

The antiviral activity of sulfated polysaccharides against dengue virus is dependent on virus serotype and host cell.

Two homogeneous sulfated polysaccharides obtained from the red seaweeds Gymnogongrus griffithsiae and Cryptonemia crenulata, the kappa/iota/nu carrageenan G3d and the dl-galactan hybrid C2S-3, were assayed for their antiviral properties against the four serotypes of dengue virus (DENV) in different host cell types. Both seaweed derivatives were selective inhibitors of DENV-2 multiplication in Vero cells with inhibitory concentration 50% (IC50) values around 1 microg/ml and selectivity indices > 1000. The compounds had a lower antiviral effect against DENV-3 (IC50 values in the range 13.9-14.2 microg/ml), an even lower effect against DENV-4 (IC50 values in the range 29.3 to > 50 microg/ml) and were totally inactive against DENV-1. With respect to the host cell, the polysulfates were inhibitors of DENV-2 and DENV-3 in the human hepatoma HepG2 and foreskin PH cells, with similar antiviral effectiveness as in Vero cells, but were totally inactive in mosquito C6/36 HT cells. Mechanistic studies demonstrated that G3d and C2S-3 were active DENV-2 inhibitors only when added together with the virus or early after infection, and both initial processes of virus adsorption and internalization are the main targets of these compounds. Therefore, the variations in antiviral activity of the polysaccharides depending on the viral serotype and the host cell may be ascribed to differences in the virus-cell interaction leading to virus entry.

Adsorption of anionic and cationic dyes on activated carbons with different surface chemistries.

The influence of the surface chemical groups of an activated carbon on the removal of different classes of dyes is evaluated. Starting from the same material (NORIT GAC 1240 PLUS), the following treatments were carried out in order to produce a series of samples with different surface chemical properties but with no major differences in their textural properties: oxidation in the liquid phase with 6M HNO(3) and 10 M H(2)O(2) (acid materials) and heat treatment at 700 degrees C in H(2) or N(2) flow (basic materials). The specific micropores volume and mesopores surface area of the materials were obtained from N(2) adsorption equilibrium isotherms at 77K. The surface chemistry was characterised by temperature programmed desorption, by the determination of the point of zero charge (pH(pzc)) and by the evaluation of the acidity/basicity of the samples. Elemental and proximate analyses were also carried out. Equilibrium isotherms of selected dyes (an acid, a basic and a reactive dye) on the mentioned samples were obtained and the results discussed in relation to their surface chemistry. In general, the Langmuir model provided the best fit for the adsorption data. It is shown that the surface chemistry of the activated carbon plays a key role in dye adsorption performance. The basic sample obtained by thermal treatment under H(2) flow at 700 degrees C is the best material for the adsorption of all the tested dyes.