The aporphine alkaloid boldine, present in Peumus boldus (boldo-do-Chile) widely used all over th... more The aporphine alkaloid boldine, present in Peumus boldus (boldo-do-Chile) widely used all over the world, was tested for the presence of genotoxic, mutagenic and recombinogenic activities in microorganisms. This alkaloid did not show genotoxic activity with or without metabolic activation in the SOS chromotest and Ames tester strains TA100, TA98 and TA102. It was not able to induce point and frameshift mutations in haploid Saccharomyces cerevisiae cells. However, mitotic recombinational events such as crossing-over and gene conversion were weakly induced in diploid yeast cells by this alkaloid. Also, boldine was able to induce weakly cytoplasmic 'petite' mutation in haploid yeast cells.
Hydrocephalus in sub-Saharan Africa, including Mozambique, is still a significant health care pro... more Hydrocephalus in sub-Saharan Africa, including Mozambique, is still a significant health care problem. Retrospective data from a previous study were used to determine patient([27]) provenance, referral patterns, and lost to follow up rates DISCUSSION: Many children with hydrocephalus in this region are not taken to health facilities for treatment for reasons including poverty, difficult access, lack of transportation and erroneous cultural interpretations. Resource limitations in terms of poorly equipped health facilities and a lack of trained health professionals also contribute. Efforts to improve prevention, early diagnosis, treatment and follow up are of utmost importance in Mozambique.
The Visual Object Tracking challenge 2014, VOT2014, aims at comparing short-term single-object vi... more The Visual Object Tracking challenge 2014, VOT2014, aims at comparing short-term single-object visual trackers that do not apply pre-learned models of object appearance. Results of 38 trackers are Authors Suppressed Due to Excessive Length presented. The number of tested trackers makes VOT 2014 the largest benchmark on short-term tracking to date. For each participating tracker, a short description is provided in the appendix. Features of the VOT2014 challenge that go beyond its VOT2013 predecessor are introduced: (i) a new VOT2014 dataset with full annotation of targets by rotated bounding boxes and per-frame attribute, (ii) extensions of the VOT2013 evaluation methodology, (iii) a new unit for tracking speed assessment less dependent on the hardware and (iv) the VOT2014 evaluation toolkit that significantly speeds up execution of experiments. The dataset, the evaluation kit as well as the results are publicly available at the challenge website 25 .
In developed countries, the incidence of neonatal hydrocephalus ranges from 3 to 5 cases per 1000... more In developed countries, the incidence of neonatal hydrocephalus ranges from 3 to 5 cases per 1000 live births, but little is known about the frequency of hydrocephalus in Africa. In Mozambique, there is no primary information related to this disorder, but using the above data, the expected incidence of neonatal hydrocephalus would range from 2900 to 4800 cases per year. This study is based on 122 children younger than 1 year with neonatal hydrocephalus, followed up between January 2010 and December 2012, their origin and treatment, and aims to evaluate difficulties with diagnosis, treatment, and follow-up in northern Mozambique. Identified cases were mainly less than 6 months old (77%), with severe macrocephaly and the classic stigmata of this condition. A high rate of follow-up loss (44.3%) was detected, particularly among children from more distant locations. Our findings contrast with the expected 1000-1700 cases that would occur in the area during the study period, being conside...
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 2014
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / m o l m u t C o m... more j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / m o l m u t C o m m u n i t y a d d r e s s : w w w . e l s e v i e r . c o m / l o c a t e / m u t r e s a b s t r a c t
Proceedings - International Conference on Image Processing, ICIP, 2010
Matching methods such as the Hungarian algorithm have recently made an appearance as an alternati... more Matching methods such as the Hungarian algorithm have recently made an appearance as an alternative to classical tracking algorithms in computer vision, since they are able to find the set of tracks that optimizes well-defined criteria over a given video sequence. However, despite being globally optimal, they carry a cost: since they require complete knowledge of the sequence, such methods cannot work with continuous video streams, a crucial requirement of realistic video surveillance applications. We were able to use the recently proposed Dynamic Hungarian Algorithm in an innovative way, adapting it to the well-known sliding window methodology. The algorithm is able to run in real-time, while retaining its optimality. We tested our implementation on several datasets, tracking humans and vehicles, and obtained reliable results using the same set of parameters on all sequences.
Proceedings of the IEEE International Conference on Computer Vision, 2011
Multiple object tracking has been formulated recently as a global optimization problem, and solve... more Multiple object tracking has been formulated recently as a global optimization problem, and solved efficiently with optimal methods such as the Hungarian Algorithm. A severe limitation is the inability to model multiple objects that are merged into a single measurement, and track them as a group, while retaining optimality. This work presents a new graph structure that encodes these multiple-match events as standard one-to-one matches, allowing computation of the solution in polynomial time. Since identities are lost when objects merge, an efficient method to identify groups is also presented, as a flow circulation problem. The problem of tracking individual objects across groups is then posed as a standard optimal assignment. Experiments show increased performance on the PETS 2006 and 2009 datasets compared to state-of-the-art algorithms.
Biflorin is an o-naphthoquinone with proven cytotoxic effects on tumor cells showing antimicrobia... more Biflorin is an o-naphthoquinone with proven cytotoxic effects on tumor cells showing antimicrobial, antitumor and antimutagenic activities. Biflorin is an isolated compound taken from the roots of the plant Capraria biflora L. (Schrophulariaceae), indigenous of the West Indies and South America, which is located in temperate or tropical areas. This compound has shown to be strongly active against grampositive and alcohol-acid-resistant bacteria. It has been efficient in inhibiting the proliferation tumor cell lines CEM, HL-60, B16, HCT-8 and MCF-7. Recently, SK-Br3 cell line was treated with biflorin showing important cytotoxic effects. In this article, information related to the first structural characterization studies are presented, as well as the latest reports concerning the biological activity of this molecule.
We studied the effect of using different heme group charge parametrization methods and schemes (M... more We studied the effect of using different heme group charge parametrization methods and schemes (Merz−Kollman, CHELPG, and single-and multiconformational RESP) on the quality of the results produced by the constant-(pH,E) MD method, applied to the redox titration of Desulfovibrio vulgaris Hildenborough cytochrome c 3 . These new and more accurate charge sets enabled us to overcome the previously reported dependence of the method's performance on the dielectric constant, ε, assigned to the protein region. In particular, we found a systematic, clear shift of the E mod toward more negative values than those previously reported, in agreement with an electrostatics based reasoning. The simulations showed strong coupling between protonating/redox sites. We were also able to capture significant direct and, especially, indirect interactions between hemes, such as those mediated by histidine 67. Our results highlight the importance of having a good quantum description of the system before deriving atomic partial charges for classic force fields.
ABSTRACT Although the latching control strategy has been recognized as an important mean of incre... more ABSTRACT Although the latching control strategy has been recognized as an important mean of increasing the efficiency of one-body point-absorbing wave energy converters (WECs), its effectiveness in two-body floating point-absorbers has been questioned in some studies. The current work investigates the increase in annual absorbed energy achieved with a simple threshold unlatching control strategy when applied to a generic two-body heaving WEC. The WEC performance is evaluated for a set of sea-states characteristic of the wave climate off the Portuguese west coast.To achieve this computationally intensive task, a new high-order numerical method for the solution of the Cummins equations is presented and used. This approach is based on a polynomial representation of the solution, whose coefficients are computed using a continuous least-squares approximation. The code has been parallelized and computations were performed at the IST cluster.
This paper presents the design methodology of a new wind turbine airfoil that achieves high perfo... more This paper presents the design methodology of a new wind turbine airfoil that achieves high performance in urban environment by increasing the maximum lift. For this purpose, an inverse method was applied to obtain a new wind turbine blade section with constant pressure-load along the chord, at the design inlet angle. In comparison with conventional blade section designs, the new airfoil has increased maximum lift, reduced leading edge suction peak and controlled soft-stall behaviour, due to a reduction of the adverse pressure gradient on the suction side. Wind tunnel experimental results confirmed the computational results.
Eddy current brakes provide a versatile way of simulating the power take-off system (PTO) in mode... more Eddy current brakes provide a versatile way of simulating the power take-off system (PTO) in model testing of small scale wave energy converters (WECs). This type of PTO simulator is based on the principle that a conductive material moving in a magnetic field generates a braking force proportional to its velocity. A bottom-hinged pitching plate WEC model has been designed using an eddy current brake as a PTO simulator. A dedicated electric current source unit was developed to provide a controllable and reliable level of DC current intensity to feed the magnetic field generating coils. Using a real-time data acquisition and control, this unit can be used to impose non-linear damping PTO characteristic curves in several types of WEC models based on eddy current brakes. In the present case, this current source has been used to simulate a constant damping PTO on a small scale pitching WEC model that has been tested in the IST wave flume. Two different cases were considered: one corresponding to a surface piercing plate and another to a fully submerged plate. Experimental results are presented for plate motion and for non-dimensional capture width.
Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2007
Diphenyl diselenide (DPDS) is an organoselenium compound with interesting pharmacological activit... more Diphenyl diselenide (DPDS) is an organoselenium compound with interesting pharmacological activities and various toxic effects. In previous reports, we demonstrated the pro-oxidant action and the mutagenic properties of this molecule in bacteria, yeast and cultured mammalian cells. This study investigated the genotoxic effects of DPDS in multiple organs (brain, kidney, liver, spleen, testes and urinary bladder) and tissues (bone marrow, lymphocytes) of mice using in vivo comet assay, in order to determine the threshold of dose at which it has beneficial or toxic effects. We assessed the mechanism underlying the genotoxicity through the measurement of GSH content and thiobarbituric acid reactive species, two oxidative stress biomarkers. Male CF-1 mice were given 0.2-200 micromol/kg BW DPDS intraperitonially. DPDS induced DNA damage in brain, liver, kidney and testes in a dose response manner, in a broad dose range at 75-200 micromol/kg with the brain showing the highest level of damage. Overall, our analysis demonstrated a high correlation among decreased levels of GSH content and an increase in lipid peroxidation and DNA damage. This finding establishes an interrelationship between pro-oxidant and genotoxic effects. In addition, DPDS was not genotoxic and did not increase lipid peroxidation levels in any organs at doses < 50 micromol/kg. Finally, pre-treatment with N-acetyl-cysteine completely prevented DPDS-induced oxidative damage by the maintenance of cellular GSH levels, reinforcing the positive relationship of DPDS-induced GSH depletion and DNA damage. In summary, DPDS induces systemic genotoxicity in mammals as it causes DNA damage in vital organs like brain, liver, kidney and testes.
Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2014
The organoselenium compound, dicholesteroyl diselenide (DCDS) is a structural analogue of dipheny... more The organoselenium compound, dicholesteroyl diselenide (DCDS) is a structural analogue of diphenyl diselenide (DPDS) and may be considered as a promising antioxidant drug in vivo. Nevertheless, little is known about the toxicological properties of DCDS. In the present study we evaluated the cytotoxic, genotoxic and mutagenic properties of DCDS in Chinese hamster lung fibroblasts (V79) and in strains of the yeast Saccharomyces cerevisiae, proficient and deficient in several DNA-repair pathways. The results with V79 cells show that DCDS induced cytotoxicity, GSH depletion and elevation of lipid peroxidation at lower concentrations than did DPDS. DCDS also generated single- and double-strand DNA breaks in V79 cells, both in the presence and in the absence of metabolic activation, as revealed by alkaline and neutral comet assays. Moreover, the induction of oxidative DNA base-damage was demonstrated by means of a modified comet assay with formamidopyrimidine-DNA glycosylase and endonuclease III. Treatment with DCDS also induced micronucleus formation in V79 cells as well as point and frame-shift mutations in a haploid wild-type strain of S. cerevisiae. Yeast mutants defective in base excision-repair proteins were the most sensitive to DCDS. Pre-incubation with N-acetylcysteine reduced DCDS's oxidative, genotoxic and mutagenic effects in yeast and in V79 cells. Our findings indicate that the presence of cholesteroyl substituents in DCDS results in elevation of its cytotoxic and genotoxic potential compared with that of DPDS in yeast and in V79 cells. However, due to dose-dependent contrasting behaviour of organoselenium compounds and differences in their toxicity in in vitro and in vivo systems, further studies are needed in order to establish the non-toxic concentration range for treatment in mammals.
Here we investigated alterations in the protein profile of Hep-2 treated with red propolis using ... more Here we investigated alterations in the protein profile of Hep-2 treated with red propolis using two-dimensional electrophoresis associated to mass spectrometry and apoptotic rates of cells treated with and without red propolis extracts through TUNEL and Annexin-V assays. A total of 325 spots were manually excised from the two-dimensional gel electrophoresis and 177 proteins were identified using LC-MS-MS. Among all proteins identified that presented differential expression, most were downregulated in presence of red propolis extract at a concentration of 120 lg/mL (IC50): GRP78, PRDX2, LDHB, VIM and TUBA1A. Only two up-regulated proteins were identified in this study in the noncytotoxic (6 lg/mL) red propolis treated group: RPLP0 and RAD23B. TUNEL staining assay showed a markedly increase in the mid-to late-stage apoptosis of Hep-2 cells induced by red propolis at concentrations of 60 and 120 lg/mL when compared with non-treated cells. The increase of late apoptosis was confirmed by in situ Annexin-V analysis in which red propolis extract induced late apoptosis in a dosedependent manner. The differences in tumor cell protein profiles warrant further investigations including isolation of major bioactive compounds of red propolis in different cell lines using proteomics and molecular tests to validate the protein expression here observed. j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / f o o d c h e m t o x non-tumor cell lines . In the present study, we used 2-DE associated to mass spectrometry to reveal the protein profiles of Hep-2 cells and apoptotic rates of cells treated with and without red propolis extracts through TUNEL and Annexin-V assays.
ABSTRACT The objective of this paper is to present the wave energy resource assessment having in ... more ABSTRACT The objective of this paper is to present the wave energy resource assessment having in view the construction of an OWC (oscillating water column) to be integrated into a new breakwater at the mouth of the Douro River in Porto (northern Portugal). The paper starts with the evaluation of the offshore wave energy resource from measured data. This is followed by the wave transformation from offshore conditions to the plant location in about 11 m water-depth. Such transformation was carried out using an inverse-ray refraction model that is described in detail. As expected, the wave power level is lower, whereas the wave energy period is higher, at the plant coastal site as compared with deep water conditions. The average wave direction rotates from approximately NW offshore to nearly West at the plant location, and the directional spread becomes smaller, which are effects of refraction as the waves propagate in waters of decreasing depth.
In order to extend the understanding of the genetical and biochemical basis of photo-activated ps... more In order to extend the understanding of the genetical and biochemical basis of photo-activated psoralen-induced DNA repair in the yeast Saccharomyces cerevisiae we have identiWed and cloned 10 pso mutants. Here, we describe the phenotypic characterization and molecular cloning of the pso10-1 mutant which is highly sensitive to photoactivated psoralens, UV 254 nm radiation and the alkylating agent methylmethane sulphonate. The pso10-1 mutant allele also confers a block in the mutagenic response to photoactivated psoralens and UV 254 nm radiation, and homoallelic diploids do not sporulate. Molecular cloning using a yeast genomic library, sequence analysis and genetic complementation experiments proved pso10-1 to be a mutant allele of gene MMS21 that encodes a SUMO ligase involved in the sumoylation of several DNA repair proteins. The ORF of pso10-1 contains a single nucleotide C!T transition at position 758, which leads to a change in amino acid sequence from serine to phenylalanine [S253F]. Pso10-1p deWnes a leaky mutant phenotype of the essential MMS21 gene, and as member of the Smc5-Smc6 complex, still has some essential functions that allow survival of the mutant. DNA repair via translesion synthesis is severely impaired as the pso10-1 mutant allele confers severely blocked induced forward and reverse mutagenesis and shows epistatic interaction with a rev3 mutant allele. By identifying the allelism of PSO10 and MMS21 we demonstrate the need of a fully functional Smc5-Smc6 complex for a WT-like adequate repair of photoactivated psoraleninduced DNA damage in yeast.
The aporphine alkaloid boldine, present in Peumus boldus (boldo-do-Chile) widely used all over th... more The aporphine alkaloid boldine, present in Peumus boldus (boldo-do-Chile) widely used all over the world, was tested for the presence of genotoxic, mutagenic and recombinogenic activities in microorganisms. This alkaloid did not show genotoxic activity with or without metabolic activation in the SOS chromotest and Ames tester strains TA100, TA98 and TA102. It was not able to induce point and frameshift mutations in haploid Saccharomyces cerevisiae cells. However, mitotic recombinational events such as crossing-over and gene conversion were weakly induced in diploid yeast cells by this alkaloid. Also, boldine was able to induce weakly cytoplasmic 'petite' mutation in haploid yeast cells.
Hydrocephalus in sub-Saharan Africa, including Mozambique, is still a significant health care pro... more Hydrocephalus in sub-Saharan Africa, including Mozambique, is still a significant health care problem. Retrospective data from a previous study were used to determine patient([27]) provenance, referral patterns, and lost to follow up rates DISCUSSION: Many children with hydrocephalus in this region are not taken to health facilities for treatment for reasons including poverty, difficult access, lack of transportation and erroneous cultural interpretations. Resource limitations in terms of poorly equipped health facilities and a lack of trained health professionals also contribute. Efforts to improve prevention, early diagnosis, treatment and follow up are of utmost importance in Mozambique.
The Visual Object Tracking challenge 2014, VOT2014, aims at comparing short-term single-object vi... more The Visual Object Tracking challenge 2014, VOT2014, aims at comparing short-term single-object visual trackers that do not apply pre-learned models of object appearance. Results of 38 trackers are Authors Suppressed Due to Excessive Length presented. The number of tested trackers makes VOT 2014 the largest benchmark on short-term tracking to date. For each participating tracker, a short description is provided in the appendix. Features of the VOT2014 challenge that go beyond its VOT2013 predecessor are introduced: (i) a new VOT2014 dataset with full annotation of targets by rotated bounding boxes and per-frame attribute, (ii) extensions of the VOT2013 evaluation methodology, (iii) a new unit for tracking speed assessment less dependent on the hardware and (iv) the VOT2014 evaluation toolkit that significantly speeds up execution of experiments. The dataset, the evaluation kit as well as the results are publicly available at the challenge website 25 .
In developed countries, the incidence of neonatal hydrocephalus ranges from 3 to 5 cases per 1000... more In developed countries, the incidence of neonatal hydrocephalus ranges from 3 to 5 cases per 1000 live births, but little is known about the frequency of hydrocephalus in Africa. In Mozambique, there is no primary information related to this disorder, but using the above data, the expected incidence of neonatal hydrocephalus would range from 2900 to 4800 cases per year. This study is based on 122 children younger than 1 year with neonatal hydrocephalus, followed up between January 2010 and December 2012, their origin and treatment, and aims to evaluate difficulties with diagnosis, treatment, and follow-up in northern Mozambique. Identified cases were mainly less than 6 months old (77%), with severe macrocephaly and the classic stigmata of this condition. A high rate of follow-up loss (44.3%) was detected, particularly among children from more distant locations. Our findings contrast with the expected 1000-1700 cases that would occur in the area during the study period, being conside...
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 2014
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / m o l m u t C o m... more j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / m o l m u t C o m m u n i t y a d d r e s s : w w w . e l s e v i e r . c o m / l o c a t e / m u t r e s a b s t r a c t
Proceedings - International Conference on Image Processing, ICIP, 2010
Matching methods such as the Hungarian algorithm have recently made an appearance as an alternati... more Matching methods such as the Hungarian algorithm have recently made an appearance as an alternative to classical tracking algorithms in computer vision, since they are able to find the set of tracks that optimizes well-defined criteria over a given video sequence. However, despite being globally optimal, they carry a cost: since they require complete knowledge of the sequence, such methods cannot work with continuous video streams, a crucial requirement of realistic video surveillance applications. We were able to use the recently proposed Dynamic Hungarian Algorithm in an innovative way, adapting it to the well-known sliding window methodology. The algorithm is able to run in real-time, while retaining its optimality. We tested our implementation on several datasets, tracking humans and vehicles, and obtained reliable results using the same set of parameters on all sequences.
Proceedings of the IEEE International Conference on Computer Vision, 2011
Multiple object tracking has been formulated recently as a global optimization problem, and solve... more Multiple object tracking has been formulated recently as a global optimization problem, and solved efficiently with optimal methods such as the Hungarian Algorithm. A severe limitation is the inability to model multiple objects that are merged into a single measurement, and track them as a group, while retaining optimality. This work presents a new graph structure that encodes these multiple-match events as standard one-to-one matches, allowing computation of the solution in polynomial time. Since identities are lost when objects merge, an efficient method to identify groups is also presented, as a flow circulation problem. The problem of tracking individual objects across groups is then posed as a standard optimal assignment. Experiments show increased performance on the PETS 2006 and 2009 datasets compared to state-of-the-art algorithms.
Biflorin is an o-naphthoquinone with proven cytotoxic effects on tumor cells showing antimicrobia... more Biflorin is an o-naphthoquinone with proven cytotoxic effects on tumor cells showing antimicrobial, antitumor and antimutagenic activities. Biflorin is an isolated compound taken from the roots of the plant Capraria biflora L. (Schrophulariaceae), indigenous of the West Indies and South America, which is located in temperate or tropical areas. This compound has shown to be strongly active against grampositive and alcohol-acid-resistant bacteria. It has been efficient in inhibiting the proliferation tumor cell lines CEM, HL-60, B16, HCT-8 and MCF-7. Recently, SK-Br3 cell line was treated with biflorin showing important cytotoxic effects. In this article, information related to the first structural characterization studies are presented, as well as the latest reports concerning the biological activity of this molecule.
We studied the effect of using different heme group charge parametrization methods and schemes (M... more We studied the effect of using different heme group charge parametrization methods and schemes (Merz−Kollman, CHELPG, and single-and multiconformational RESP) on the quality of the results produced by the constant-(pH,E) MD method, applied to the redox titration of Desulfovibrio vulgaris Hildenborough cytochrome c 3 . These new and more accurate charge sets enabled us to overcome the previously reported dependence of the method's performance on the dielectric constant, ε, assigned to the protein region. In particular, we found a systematic, clear shift of the E mod toward more negative values than those previously reported, in agreement with an electrostatics based reasoning. The simulations showed strong coupling between protonating/redox sites. We were also able to capture significant direct and, especially, indirect interactions between hemes, such as those mediated by histidine 67. Our results highlight the importance of having a good quantum description of the system before deriving atomic partial charges for classic force fields.
ABSTRACT Although the latching control strategy has been recognized as an important mean of incre... more ABSTRACT Although the latching control strategy has been recognized as an important mean of increasing the efficiency of one-body point-absorbing wave energy converters (WECs), its effectiveness in two-body floating point-absorbers has been questioned in some studies. The current work investigates the increase in annual absorbed energy achieved with a simple threshold unlatching control strategy when applied to a generic two-body heaving WEC. The WEC performance is evaluated for a set of sea-states characteristic of the wave climate off the Portuguese west coast.To achieve this computationally intensive task, a new high-order numerical method for the solution of the Cummins equations is presented and used. This approach is based on a polynomial representation of the solution, whose coefficients are computed using a continuous least-squares approximation. The code has been parallelized and computations were performed at the IST cluster.
This paper presents the design methodology of a new wind turbine airfoil that achieves high perfo... more This paper presents the design methodology of a new wind turbine airfoil that achieves high performance in urban environment by increasing the maximum lift. For this purpose, an inverse method was applied to obtain a new wind turbine blade section with constant pressure-load along the chord, at the design inlet angle. In comparison with conventional blade section designs, the new airfoil has increased maximum lift, reduced leading edge suction peak and controlled soft-stall behaviour, due to a reduction of the adverse pressure gradient on the suction side. Wind tunnel experimental results confirmed the computational results.
Eddy current brakes provide a versatile way of simulating the power take-off system (PTO) in mode... more Eddy current brakes provide a versatile way of simulating the power take-off system (PTO) in model testing of small scale wave energy converters (WECs). This type of PTO simulator is based on the principle that a conductive material moving in a magnetic field generates a braking force proportional to its velocity. A bottom-hinged pitching plate WEC model has been designed using an eddy current brake as a PTO simulator. A dedicated electric current source unit was developed to provide a controllable and reliable level of DC current intensity to feed the magnetic field generating coils. Using a real-time data acquisition and control, this unit can be used to impose non-linear damping PTO characteristic curves in several types of WEC models based on eddy current brakes. In the present case, this current source has been used to simulate a constant damping PTO on a small scale pitching WEC model that has been tested in the IST wave flume. Two different cases were considered: one corresponding to a surface piercing plate and another to a fully submerged plate. Experimental results are presented for plate motion and for non-dimensional capture width.
Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2007
Diphenyl diselenide (DPDS) is an organoselenium compound with interesting pharmacological activit... more Diphenyl diselenide (DPDS) is an organoselenium compound with interesting pharmacological activities and various toxic effects. In previous reports, we demonstrated the pro-oxidant action and the mutagenic properties of this molecule in bacteria, yeast and cultured mammalian cells. This study investigated the genotoxic effects of DPDS in multiple organs (brain, kidney, liver, spleen, testes and urinary bladder) and tissues (bone marrow, lymphocytes) of mice using in vivo comet assay, in order to determine the threshold of dose at which it has beneficial or toxic effects. We assessed the mechanism underlying the genotoxicity through the measurement of GSH content and thiobarbituric acid reactive species, two oxidative stress biomarkers. Male CF-1 mice were given 0.2-200 micromol/kg BW DPDS intraperitonially. DPDS induced DNA damage in brain, liver, kidney and testes in a dose response manner, in a broad dose range at 75-200 micromol/kg with the brain showing the highest level of damage. Overall, our analysis demonstrated a high correlation among decreased levels of GSH content and an increase in lipid peroxidation and DNA damage. This finding establishes an interrelationship between pro-oxidant and genotoxic effects. In addition, DPDS was not genotoxic and did not increase lipid peroxidation levels in any organs at doses < 50 micromol/kg. Finally, pre-treatment with N-acetyl-cysteine completely prevented DPDS-induced oxidative damage by the maintenance of cellular GSH levels, reinforcing the positive relationship of DPDS-induced GSH depletion and DNA damage. In summary, DPDS induces systemic genotoxicity in mammals as it causes DNA damage in vital organs like brain, liver, kidney and testes.
Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2014
The organoselenium compound, dicholesteroyl diselenide (DCDS) is a structural analogue of dipheny... more The organoselenium compound, dicholesteroyl diselenide (DCDS) is a structural analogue of diphenyl diselenide (DPDS) and may be considered as a promising antioxidant drug in vivo. Nevertheless, little is known about the toxicological properties of DCDS. In the present study we evaluated the cytotoxic, genotoxic and mutagenic properties of DCDS in Chinese hamster lung fibroblasts (V79) and in strains of the yeast Saccharomyces cerevisiae, proficient and deficient in several DNA-repair pathways. The results with V79 cells show that DCDS induced cytotoxicity, GSH depletion and elevation of lipid peroxidation at lower concentrations than did DPDS. DCDS also generated single- and double-strand DNA breaks in V79 cells, both in the presence and in the absence of metabolic activation, as revealed by alkaline and neutral comet assays. Moreover, the induction of oxidative DNA base-damage was demonstrated by means of a modified comet assay with formamidopyrimidine-DNA glycosylase and endonuclease III. Treatment with DCDS also induced micronucleus formation in V79 cells as well as point and frame-shift mutations in a haploid wild-type strain of S. cerevisiae. Yeast mutants defective in base excision-repair proteins were the most sensitive to DCDS. Pre-incubation with N-acetylcysteine reduced DCDS's oxidative, genotoxic and mutagenic effects in yeast and in V79 cells. Our findings indicate that the presence of cholesteroyl substituents in DCDS results in elevation of its cytotoxic and genotoxic potential compared with that of DPDS in yeast and in V79 cells. However, due to dose-dependent contrasting behaviour of organoselenium compounds and differences in their toxicity in in vitro and in vivo systems, further studies are needed in order to establish the non-toxic concentration range for treatment in mammals.
Here we investigated alterations in the protein profile of Hep-2 treated with red propolis using ... more Here we investigated alterations in the protein profile of Hep-2 treated with red propolis using two-dimensional electrophoresis associated to mass spectrometry and apoptotic rates of cells treated with and without red propolis extracts through TUNEL and Annexin-V assays. A total of 325 spots were manually excised from the two-dimensional gel electrophoresis and 177 proteins were identified using LC-MS-MS. Among all proteins identified that presented differential expression, most were downregulated in presence of red propolis extract at a concentration of 120 lg/mL (IC50): GRP78, PRDX2, LDHB, VIM and TUBA1A. Only two up-regulated proteins were identified in this study in the noncytotoxic (6 lg/mL) red propolis treated group: RPLP0 and RAD23B. TUNEL staining assay showed a markedly increase in the mid-to late-stage apoptosis of Hep-2 cells induced by red propolis at concentrations of 60 and 120 lg/mL when compared with non-treated cells. The increase of late apoptosis was confirmed by in situ Annexin-V analysis in which red propolis extract induced late apoptosis in a dosedependent manner. The differences in tumor cell protein profiles warrant further investigations including isolation of major bioactive compounds of red propolis in different cell lines using proteomics and molecular tests to validate the protein expression here observed. j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / f o o d c h e m t o x non-tumor cell lines . In the present study, we used 2-DE associated to mass spectrometry to reveal the protein profiles of Hep-2 cells and apoptotic rates of cells treated with and without red propolis extracts through TUNEL and Annexin-V assays.
ABSTRACT The objective of this paper is to present the wave energy resource assessment having in ... more ABSTRACT The objective of this paper is to present the wave energy resource assessment having in view the construction of an OWC (oscillating water column) to be integrated into a new breakwater at the mouth of the Douro River in Porto (northern Portugal). The paper starts with the evaluation of the offshore wave energy resource from measured data. This is followed by the wave transformation from offshore conditions to the plant location in about 11 m water-depth. Such transformation was carried out using an inverse-ray refraction model that is described in detail. As expected, the wave power level is lower, whereas the wave energy period is higher, at the plant coastal site as compared with deep water conditions. The average wave direction rotates from approximately NW offshore to nearly West at the plant location, and the directional spread becomes smaller, which are effects of refraction as the waves propagate in waters of decreasing depth.
In order to extend the understanding of the genetical and biochemical basis of photo-activated ps... more In order to extend the understanding of the genetical and biochemical basis of photo-activated psoralen-induced DNA repair in the yeast Saccharomyces cerevisiae we have identiWed and cloned 10 pso mutants. Here, we describe the phenotypic characterization and molecular cloning of the pso10-1 mutant which is highly sensitive to photoactivated psoralens, UV 254 nm radiation and the alkylating agent methylmethane sulphonate. The pso10-1 mutant allele also confers a block in the mutagenic response to photoactivated psoralens and UV 254 nm radiation, and homoallelic diploids do not sporulate. Molecular cloning using a yeast genomic library, sequence analysis and genetic complementation experiments proved pso10-1 to be a mutant allele of gene MMS21 that encodes a SUMO ligase involved in the sumoylation of several DNA repair proteins. The ORF of pso10-1 contains a single nucleotide C!T transition at position 758, which leads to a change in amino acid sequence from serine to phenylalanine [S253F]. Pso10-1p deWnes a leaky mutant phenotype of the essential MMS21 gene, and as member of the Smc5-Smc6 complex, still has some essential functions that allow survival of the mutant. DNA repair via translesion synthesis is severely impaired as the pso10-1 mutant allele confers severely blocked induced forward and reverse mutagenesis and shows epistatic interaction with a rev3 mutant allele. By identifying the allelism of PSO10 and MMS21 we demonstrate the need of a fully functional Smc5-Smc6 complex for a WT-like adequate repair of photoactivated psoraleninduced DNA damage in yeast.
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Papers by Joao Henriques