Publications by authors named "Elsa Dias"

19 Publications

  • Page 1 of 1

Antioxidant and Cytoprotective Properties of Cyanobacteria: Potential for Biotechnological Applications.

Toxins (Basel) 2020 08 26;12(9). Epub 2020 Aug 26.

Laboratory of Biology and Ecotoxicology, Department Environmental Health, National Institute of Health Dr. Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal.

Antioxidant compounds from cyanobacteria may constitute a natural alternative to current synthetic antioxidants, which contain preservatives and suspected toxicity. In this work, we evaluate the antioxidant potential of cyanobacterial strains of distinct species/genus isolated from freshwater (n = 6), soil (n = 1) and wastewater (n = 1) environments. Lyophilized biomass obtained from in-vitro cultures of those strains was extracted with ethanol and methanol. The antioxidant potential was evaluated by chemical (DPPH scavenging method, β-carotene bleaching assay, determination of total phenolic and total flavonoid compounds) and biological (HO-exposed HEK293T cell line model) approach. Some strains showed high yields of antioxidant activity by the DPPH assay (up to 10.7% IP/20.7 TE μg/mL) and by the β-carotene bleaching assay (up to 828.94 AAC), as well as significant content in phenolic (123.16 mg EAG/g DW) and flavonoid (900.60 mg EQR/g DW) compounds. Normalization of data in a "per cell" or "per cell volume" base might facilitate the comparison between strains. Additionally, most of the cyanobacterial extracts conferred some degree of protection to HEK293T cells against the HO-induced cytotoxicity. Freshwater (LMECYA 009) and (LMECYA 088), terrestrial (LMECYA 291) and wastewater (LEGE 06224) seem to be promising strains for further investigation on cyanobacteria antioxidant potential.
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http://dx.doi.org/10.3390/toxins12090548DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7551995PMC
August 2020

Isolation and Characterization of Strains from Finished Drinking Water.

Toxins (Basel) 2020 01 8;12(1). Epub 2020 Jan 8.

Department of Environmental Health, National Institute of Health Dr. Ricardo Jorge (INSA), Av. Padre Cruz, 1649-016 Lisbon, Portugal.

In the summer of 2015, an intense cyanobacterial bloom producing geosmin/2-methylisoborneol (MIB) occurred in the Roxo freshwater reservoir in Alentejo, Portugal. The drinking water supplied from the Roxo water treatment plant (WTP) exhibited an unpleasant odor/taste and a significant cyanobacteria density was detected in the finished water at the exit of the WTP. Cyanobacteria were not evaluated downstream of the WTP, namely, at the city reservoir. The aim of this work was to isolate and characterize viable cyanobacteria present in finished water (exit of the WTP and city reservoir) that withstand conventional water treatment. Treated water samples collected at both sites were inoculated in Z8 culture medium to provide the conditions for putative cyanobacterial growth. After 30 days, filamentous cyanobacteria were observed in cultures inoculated with samples from the exit point of the WTP. Viable trichomes were isolated and identified as by morphometric and molecular analysis. None of the isolates were cylindrospermopsin/microcystin producers, as confirmed by ELISA and amplification of corresponding genes (/ and //). ELISA results were positive for saxitoxin, but saxitoxin and derivatives were not detected by liquid chromatography with fluorescence detection (LC-FLD), nor were their related genes (/////). To our knowledge, this is the first report on the establishment of cultures of that resisted water treatment processes.
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http://dx.doi.org/10.3390/toxins12010040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7020411PMC
January 2020

[Recommendations About Multiple Sclerosis Management During Pregnancy, Partum and Post-Partum: Consensus Position of The Portuguese Multiple Sclerosis Study Group and The Portuguese Society of Obstetrics and Maternal-Fetal Medicine].

Acta Med Port 2018 Dec 28;31(12):785-795. Epub 2018 Dec 28.

Serviço de Neurologia. Hospital Beatriz Ângelo. Loures. Portugal.

Multiple sclerosis typically affects young women of reproductive age. Therefore, all healthcare providers involved in the follow-up of multiple sclerosis patients must be prepared to discuss pregnancy and breastfeeding issues, and provide the best possible counselling. However, there are still many doubts and heterogeneous clinical approaches partly due to the lack of consensus and guidelines. Concerning the handling of disease modifying therapies during pregnancy and the postpartum period, uncertainties have been complicated by the increase in recent years of the number of available treatments. This article aims to present the state-of-the-art and provide guidance based on the best level of available evidence and expert opinion regarding the management of multiple sclerosis patients at different stages: pregnancy planning, pregnancy, partum, and the postpartum period.
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http://dx.doi.org/10.20344/amp.10752DOI Listing
December 2018

Deciphering the role of cyanobacteria in water resistome: Hypothesis justifying the antibiotic resistance (phenotype and genotype) in Planktothrix genus.

Sci Total Environ 2019 Feb 12;652:447-454. Epub 2018 Oct 12.

National Reference Laboratory of Antibiotic Resistances and Healthcare Associated Infections, Department of Infectious Diseases, National Institute of Health Dr. Ricardo Jorge, Lisbon, Portugal; Centre for the Study of Animal Sciences, University of Porto, Porto, Portugal.

The importance of environmental microorganisms in the emergence and dissemination of antibiotic resistance is an undeniable fact. However, cyanobacteria are not seen yet as putative players in the dynamic of environmental resistome, despite their ubiquity in water environments, where they are exposed to antibiotic pollution and in straight contact with native and pathogenic bacteria harboring antibiotic resistance genes (ARGs). In this work we evaluated the susceptibility of 8 strains of Planktothrix agardhii (from surface freshwaters reservoirs) and 8 strains of Planktothrix mougeotii (from a wastewater treatment plant) to several classes of antibiotics, using a microplate dilution method previously described by us. We also search for ARGs in those strains by molecular methods. None of the 16 tested strains were susceptible to trimethoprim, nalidixic acid and norfloxacin, from 0.0015-1.6 mg/L, but all were susceptible to streptomycin, gentamicin, kanamycin, ceftazidime and ceftriaxone. The minimum inhibitory concentrations (MICs) ranged between 0.05-0.8 mg/L for the aminoglycosides and 0.4-1.6 mg/L for the two β‑lactams. Major differences were found in the susceptibility to amoxicillin and tetracycline, with P. agardhii being susceptible (MIC of 0.05 mg/L and 0.4 mg/L, respectively) and P. mougeotii not susceptible. These distinct responses might be due to differences between species. However, the lower susceptibility of wastewater strains suggests that antibiotic resistance phenotype of cyanobacteria is related with their habitat. The failure to detect acquired genes conferring resistance to trimethoprim/quinolones, strongly supports the hypothesis that cyanobacteria are intrinsically resistant to these antibiotics. Interestingly, we detected a class-1-type integron and a sul1 gene in 3 strains of both P. agardhii and P. mougeotii, which supports the possibility of cyanobacteria to acquire and transfer antibiotic resistance determinants. In conclusion, the identification of ARGs and related integrons, as well as the reduced susceptibility to some antibiotics, suggests that cyanobacteria may play a role on environmental resistome.
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http://dx.doi.org/10.1016/j.scitotenv.2018.10.167DOI Listing
February 2019

Risk Levels of Toxic Cyanobacteria in Portuguese Recreational Freshwaters.

Toxins (Basel) 2017 10 18;9(10). Epub 2017 Oct 18.

Department of Environmental Health, National Institute of Health Dr. Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal.

Portuguese freshwater reservoirs are important socio-economic resources, namely for recreational use. National legislation concerning bathing waters does not include mandatory levels or guidelines for cyanobacteria and cyanotoxins. This is an issue of concern since cyanotoxin-based evidence is insufficient to change the law, and the collection of scientific evidence has been hampered by the lack of regulatory levels for cyanotoxins in bathing waters. In this work, we evaluate the profile of cyanobacteria and microcystins (MC) in eight freshwater reservoirs from the center of Portugal, used for bathing/recreation, in order to determine the risk levels concerning toxic cyanobacteria occurrence. Three of the reservoirs did not pose a risk of MC contamination. However, two reservoirs presented a high risk in 7% of the samples according to the World Health Organization (WHO) guidelines for MC in bathing waters (above 20 µg/L). In the remaining three reservoirs, the risk concerning microcystins occurrence was low. However, they exhibited recurrent blooms and persistent contamination with MC up to 4 µg/L. Thus, the risk of exposure to MC and potential acute and/or chronic health outcomes should not be disregarded in these reservoirs. These results contribute to characterize the cyanobacterial blooms profile and to map the risk of toxic cyanobacteria and microcystins occurrence in Portuguese inland waters.
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http://dx.doi.org/10.3390/toxins9100327DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5666374PMC
October 2017

Assessing the antibiotic susceptibility of freshwater Cyanobacteria spp.

Front Microbiol 2015 11;6:799. Epub 2015 Aug 11.

National Reference Laboratory of Antimicrobial Resistances and Healthcare Associated Infections, Department of Infectious Diseases, National Institute of Health Dr. Ricardo Jorge Lisbon, Portugal.

Freshwater is a vehicle for the emergence and dissemination of antibiotic resistance. Cyanobacteria are ubiquitous in freshwater, where they are exposed to antibiotics and resistant organisms, but their role on water resistome was never evaluated. Data concerning the effects of antibiotics on cyanobacteria, obtained by distinct methodologies, is often contradictory. This emphasizes the importance of developing procedures to understand the trends of antibiotic susceptibility in cyanobacteria. In this study we aimed to evaluate the susceptibility of four cyanobacterial isolates from different genera (Microcystis aeruginosa, Aphanizomenon gracile, Chrisosporum bergii, Planktothix agradhii), and among them nine isolates from the same specie (M. aeruginosa) to distinct antibiotics (amoxicillin, ceftazidime, ceftriaxone, kanamycine, gentamicine, tetracycline, trimethoprim, nalidixic acid, norfloxacin). We used a method adapted from the bacteria standard broth microdilution. Cyanobacteria were exposed to serial dilution of each antibiotic (0.0015-1.6 mg/L) in Z8 medium (20 ± 1°C; 14/10 h L/D cycle; light intensity 16 ± 4 μEm(-2)s(-1)). Cell growth was followed overtime (OD450nm /microscopic examination) and the minimum inhibitory concentrations (MICs) were calculated for each antibiotic/isolate. We found that β-lactams exhibited the lower MICs, aminoglycosides, tetracycline and norfloxacine presented intermediate MICs; none of the isolates were susceptible to trimethoprim and nalidixic acid. The reduced susceptibility of all tested cyanobacteria to some antibiotics suggests that they might be naturally non-susceptible to these compounds, or that they might became non-susceptible due to antibiotic contamination pressure, or to the transfer of genes from resistant bacteria present in the environment.
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http://dx.doi.org/10.3389/fmicb.2015.00799DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4531292PMC
August 2015

Current perspectives on the dynamics of antibiotic resistance in different reservoirs.

Res Microbiol 2015 Sep 4;166(7):594-600. Epub 2015 Aug 4.

National Reference Laboratory of Antibiotic Resistances and Healthcare Associated Infections, National Institute of Health Dr. Ricardo Jorge, Lisbon, Portugal. Electronic address:

Antibiotic resistance consists of a dynamic web. In this review, we describe the path by which different antibiotic residues and antibiotic resistance genes disseminate among relevant reservoirs (human, animal, and environmental settings), evaluating how these events contribute to the current scenario of antibiotic resistance. The relationship between the spread of resistance and the contribution of different genetic elements and events is revisited, exploring examples of the processes by which successful mobile resistance genes spread across different niches. The importance of classic and next generation molecular approaches, as well as action plans and policies which might aid in the fight against antibiotic resistance, are also reviewed.
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http://dx.doi.org/10.1016/j.resmic.2015.07.009DOI Listing
September 2015

Characterization of the toxicological effects of aminocarb on rats: hematological, biochemical, and histological analyses.

J Toxicol Environ Health A 2014 ;77(14-16):849-55

a Departamento de Biologia, CICECO , Universidade de Aveiro , Aveiro , Portugal.

Aminocarb is a widely applied carbamate insecticide with action of controlling pests such as Lepidoptera and Coleoptera. In this study, subchronic effects on Wistar rats were investigated using hematological, biochemical, and histological techniques. Rats were exposed orally at sublethal levels of 10, 20, or 40 mg/kg body weight (groups A, B, and C, respectively) for 14 d. Hematological results revealed no statistical differences after 1 d of exposure but significant reduction in white blood cells detected after 7 d of exposure in group C, as well as, in all treated groups after 14 d of exposure. Biochemical data showed a decrease of acetylcholinesterase activity in all groups after 1 d of exposure with a return to normal after 7 and 14 d. Significant increase in alkaline phosphatase activity of rats exposed to aminocarb was noted after 7 d of treatment. The levels of triglycerides were also significantly decreased. The present investigation also showed a significant increase in content of serum urea and creatinine in animals from group A (14 d), and from groups B and C (7 and 14 d). Histological results demonstrated hemorrhagic focus on hepatic and renal parenchyma in all exposed groups. Taken together, the attained results were dose dependent and indicated adverse effects of aminocarb on hepatic and renal functions, as well as on immune responsiveness at sublethal tested doses.
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http://dx.doi.org/10.1080/15287394.2014.909305DOI Listing
September 2014

Genotoxicity of microcystin-LR in in vitro and in vivo experimental models.

Biomed Res Int 2014 18;2014:949521. Epub 2014 May 18.

Department of Human Genetics, National Institute of Health Dr. Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisbon, Portugal.

Microcystin-LR (MCLR) is a cyanobacterial toxin known for its acute hepatotoxicity. Despite being recognized as tumour promoter, its genotoxicity is far from being completely clarified, particularly in organs other than liver. In this work, we used the comet and/or the micronucleus (MN) assays to study the genotoxicity of MCLR in kidney- (Vero-E6) and liver-derived (HepG2) cell lines and in blood cells from MCLR-exposed mice. MCLR treatment (5 and 20 μM) caused a significant induction in the MN frequency in both cell lines and, interestingly, a similar positive effect was observed in mouse reticulocytes (37.5 μg MCLR/kg, i.p. route). Moreover, the FISH-based analysis of the MN content (HepG2 cells) suggested that MCLR induces both chromosome breaks and loss. On the other hand, the comet assay results were negative in Vero-E6 cells and in mouse leukocytes, with the exception of a transient increase in the level of DNA damage 30 minutes after mice exposure. Overall, the present findings contributed to increase the weight of evidence in favour of MCLR genotoxicity, based on its capacity to induce permanent genetic damage either in vitro or in vivo. Moreover, they suggest a clastogenic and aneugenic mode of action that might underlie a carcinogenic effect.
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http://dx.doi.org/10.1155/2014/949521DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4052155PMC
February 2015

Subacute effects of the thiodicarb pesticide on target organs of male Wistar rats: biochemical, histological, and flow cytometry studies.

J Toxicol Environ Health A 2013 ;76(9):533-9

Departamento de Biologia & CICECO, Universidade de Aveiro, Aveiro, Portugal.

Thiodicarb, a carbamate pesticide widely used on crops, may pose several environmental and health concerns. This study aimed to explore its toxicological profile on male rats using hematological, biochemical, histopathological, and flow cytometry markers. Exposed animals were dosed daily at 10, 20, or 40 mg/kg/body weight (group A, B, and C, respectively) during 30 d. No significant changes were observed in hematological parameters among all groups. After 10 d, a decrease of total cholesterol levels was noted in rats exposed to 40 mg/kg. Aspartate aminotransferase (AST) activity increased (group A at 20 d; groups A and B at 30 d) and alkaline phosphatase (ALP) (group B at 30 d) activity significantly reduced. At 30 d a decrease of some of the other evaluated parameters was observed with total cholesterol and urea levels in group A as well as total protein and creatinine levels in groups A and B. Histological results demonstrated multi-organ dose-related damage in thiodicarb-exposed animals, evidenced as hemorrhagic and diffuse vacuolation in hepatic tissue; renal histology showed disorganized glomeruli and tubular cell degeneration; spleen was ruptured with white pulp and clusters of iron deposits within red pulp; significant cellular loss was noted at the cortex of thymus; and degenerative changes were observed within testis. The histopathologic alterations were most prominent in the high-dose group. Concerning flow cytometry studies, an increase of lymphocyte number, especially T lymphocytes, was seen in blood samples from animals exposed to the highest dose. Taken together, these results indicate marked systemic organ toxicity in rats after subacute exposure to thiodicarb.
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http://dx.doi.org/10.1080/15287394.2013.785216DOI Listing
August 2013

Involvement of endoplasmic reticulum and autophagy in microcystin-LR toxicity in Vero-E6 and HepG2 cell lines.

Toxicol In Vitro 2013 Feb 23;27(1):138-48. Epub 2012 Sep 23.

Department of Environmental Health, National Health Institute Dr Ricardo Jorge, Av Padre Cruz, 1649-016 Lisbon, Portugal.

This work investigates the involvement of the endoplasmic reticulum (ER) and autophagy in microcystin-LR (MCLR) toxicity in Vero-E6 and HepG2 cell lines. Additionally, morphological alterations induced by MCLR in lysosomes and mitochondria were studied. Cytotoxicity evaluation showed that pure MCLR and MCLR from LMECYA110 extract induce concentration dependent viability decays after 24h exposure. HepG2 cells showed an increased sensitivity to MCLR than Vero cells, with lower cytotoxic thresholds and EC(50) values. Conversely, LC3B immunofluorescence showed that autophagy is triggered in both cell lines as a survival response to low MCLR concentrations. Furthermore, MCLR induced a MCLR concentration-dependent decrease of GRP94 expression in HepG2 cells while in Vero cells no alteration was observed. This suggests the involvement of the ER in HepG2 apoptosis elicited by MCLR, while in Vero cells ER destructuration could be a consequence of cytoskeleton inflicted damages. Additionally, in both cell lines, lysosomal destabilization preceded mitochondrial impairment which occurred at high toxin concentrations. Although not an early cellular target of MCLR, mitochondria appears to serve as central mediators of different signaling pathways elicited by the organelles involved in MCLR toxicity. As a result, kidney and hepatic cell lines exhibit cell type and dose-dependent mechanisms to overcome MCLR toxicity.
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http://dx.doi.org/10.1016/j.tiv.2012.09.009DOI Listing
February 2013

Process for detecting Helicobacter pylori using aliphatic amides.

Anal Bioanal Chem 2011 Oct 6;401(6):1889-98. Epub 2011 Aug 6.

QOPNA, Department of Chemistry, University of Aveiro, Campus de Santiago, Aveiro, Portugal.

Helicobacter pylori diagnosis is fundamental in the management of gastrointestinal pathologies, whose current clinical guidelines support a non-invasive 'test-and-treat' strategy. As such, the present work reports the basis of a new, low-cost, specific breath test based on the detection of volatile carboxylic acids resulting from the hydrolysis of short-chain aliphatic amides by H. pylori amidases. Propionamide and butyramide, which are metabolized by amidases to propionic and butyric acids, were elected for this study. Conditions for the extraction of these acids from a vapour phase were optimized concerning the use of solid-phase microextraction (SPME) followed by gas chromatography-quadrupole mass spectrometry (GC-qMS) analysis. SPME-GC-qMS was then used to detect the acids released into a vapour phase upon incubation of a H. pylori reference strain J99 or a clinical specimen with the amides. These experiments have demonstrated that the administration of less than 9 mg of propionamide and/or butyramide to H. pylori cultures, in loads recognized to cause infection (10(6)-10(9) cells), resulted in the formation of detectable and/or quantifiable amounts of propionic and/or butyric acids after 30 min incubation. As such, propionic and butyric acids can be used as biomarkers for H. pylori upon incubation with the corresponding amides. SPME-GC-qMS was also used to verify the hepatic stability of the acids. These experiments were conducted in mouse liver cells and revealed no signs of metabolization that could compromise their bioavailability in future in vivo assays. Moreover, SPME-GC-qMS permitted the detection of both acids in amounts as low as 0.8 μg in systems mimicking exhaled breath, demonstrating the sensitivity of the method for these compounds.
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http://dx.doi.org/10.1007/s00216-011-5259-xDOI Listing
October 2011

Gestational diabetes mellitus complicating twin pregnancies.

J Perinat Med 2011 07;39(4):437-40

Department of Maternal-Fetal Medicine and Maternity Dr. Alfredo da Costa, Lisbon, Portugal.

Objective: To compare outcomes of twin pregnancies with and without gestational diabetes mellitus (GDM).

Study Design: We compared 105 twin pregnancies with GDM (7.8% of all twin pregnancies) to 315 controls without GDM, matched for gestational age, chorionicity and year of birth.

Results: Pre-gravid obesity appears to predispose women to GDM during twin pregnancy [odds ratio (OR) 3.5; 95% confidence interval (CI) 1.7, 7.0]. Overweight and obese women that subsequently developed GDM during their twin gestation were less likely to conceive spontaneously (OR 0.4; 95% CI 0.3, 0.7). Twins from the GDM group had more respiratory distress syndrome (RDS, OR 2.2; 95% CI 1.3, 3.7) and had a three-fold, but not significantly increased perinatal mortality rate. Birth weight characteristics were similar in both groups.

Conclusion: Twin pregnancies complicated by GDM might be associated with pre-pregnancy maternal obesity and are at increased risk of RDS and non-significant increased risk of perinatal death.
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http://dx.doi.org/10.1515/jpm.2011.048DOI Listing
July 2011

Comparative study of the cytotoxic effect of microcistin-LR and purified extracts from Microcystis aeruginosa on a kidney cell line.

Toxicon 2009 Apr;53(5):487-95

National Institute of Health Dr. Ricardo Jorge, Department of Genetics, Av. Padre Cruz, 1649-016 Lisbon, Portugal.

Microcystin-LR (MCLR) is a potent hepatotoxin, but increasing evidences suggest that it might also induce kidney injury. The aim of this work was to evaluate the cytotoxicity of MCLR on a kidney cell line (Vero-E6). Cells were exposed for up to 72 h either to Microcystis aeruginosa extracts from both MCLR-producer and non-MCLR-producer isolates or to pure MCLR (1.5-200 microM). The cytotoxic effects were evaluated by several cell viability assays (MTT, Neutral Red and LDH). Pure MCLR, the extract from MCLR-producer and the mixture of the non-MCLR-producer with pure MCLR, induced cell viability decrease in a similar dose/time-dependent manner. Conversely, no effects were induced by the extract of non-MCLR-producer. These results suggest that the cytotoxic effects of M. aeruginosa extract were due to MCLR and excluded the eventual toxicity of other cyanobacteria bioactive compounds. The lowest cytotoxic MCLR concentration varied between 11 and 100 microM depending on the employed cell viability assay and is within the range of MCLR dosage reported to affect other mammalian cell lines. The NR assay was the most sensitive to evaluate the MCLR-induced cytotoxicity. Our results suggest that Vero-E6 cell line may constitute a cell model to evaluate the nephrotoxicity of microcystins.
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http://dx.doi.org/10.1016/j.toxicon.2009.01.029DOI Listing
April 2009

Perinatal outcome and change in body mass index in mothers of dichorionic twins: a longitudinal cohort study.

Twin Res Hum Genet 2008 Apr;11(2):219-23

Department of Maternal-fetal Medicine and Neonatology, Maternidade Dr Alfredo da Costa, Lisbon, Portugal.

We used a prospective cohort to analyze the effect of change in BMI rather than change in weight, in mothers carrying dichorionic twins from a population that did not receive any dietary intervention. A total of 269 mothers (150 nulliparas and 119 multiparas) were evaluated. The average change (%) from the pre-gravid BMI was 7.2+/-6.1, 17.4+/-8.2, and 28.7+/-10.8, at 12-14, 22-25, and 30-34 weeks, respectively, without difference between nulliparas and multiparas. The comparison between maternities below or above the average change from the pregravid BMI failed to demonstrate an advantage (in terms of total twin birthweight and gestational age) of an above average change from the pregravid BMI, even when the lower versus upper quartiles were compared. Our observations reached different conclusions regarding the recommended universal dietary intervention in twin gestations. A cautious approach is advocated towards seemingly harmless excess weight gain, as normal weight women may turn overweight, or even obese, by the end of pregnancy, and be exposed to the untoward effects of obesity on future health and body image.
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http://dx.doi.org/10.1375/twin.11.2.219DOI Listing
April 2008

Prospective risk of intrauterine death of monochorionic-diamniotic twins.

Am J Obstet Gynecol 2006 Jul 27;195(1):134-9. Epub 2006 Apr 27.

Department of Maternal-Fetal Medicine Maternity Dr Alfredo da Costa, Lisbon, Portugal.

Objective: The purpose of this study was to calculate the prospective risk of fetal death in monochorionic-diamniotic twins.

Study Design: We evaluated 193 monochorionic diamniotic twin pregnancies that were followed and delivered after 24 weeks. Surveillance included cardiotocography and sonography performed at least once weekly. The prospective risk of fetal death was calculated as the total number of deaths at the beginning of the gestational period divided by the number of continuing pregnancies at or beyond that period.

Results: The fetal death rate was 5 of 193 pregnancies (2.6%; 95% CI, 1.1, 5.9); the prospective risk of stillbirth per pregnancy after 32 weeks of gestation was 1.2% (95% CI, 0.3% - 4.2%).

Conclusion: Under intensive surveillance, the prospective risk of fetal death in monochorionic-diamniotic pregnancies after 32 weeks of gestation is much lower than reported and does not support a policy of elective preterm delivery.
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http://dx.doi.org/10.1016/j.ajog.2006.01.099DOI Listing
July 2006

Induction of labor with oral misoprostol in nulliparous mothers of twins.

J Perinat Med 2006 ;34(2):111-4

Department of Maternal-Fetal Medicine and Neonatology, Maternity Dr. Alfredo da Costa, Lisbon, Portugal.

The efficacy and safety of oral misoprostol for labor induction of twins is unknown. We conducted a retrospective case-control study to evaluate the use of oral misoprostol in near term (> or =35 weeks) twin pregnancies in nulliparas. Eligible cases were given 100 mcg oral misoprostol, which was repeated after 6 h if labor did not start. Either a third dose or diluted oxytocin infusion were given in intractable cases. Diluted oxytocin infusion was used for augmentation. Controls were nulliparas delivered at > or =35 weeks by elective cesarean section. The two groups were comparable in most aspects, except for fetal malpresentation, which was the major reason for avoiding induction. Of the 69 patients in whom labor was induced, 53 (76.8%) had a vaginal birth, 3 (4.3%) had a combined twin delivery, and 13 (18.8%) had a cesarean during labor. The mean length of stay of the neonates was significantly shorter among study cases, without significant difference in the frequency of delayed discharges as an overall proxy for neonatal complications. Labor induction with oral misoprostol could be offered to patients in whom near term vaginal twin delivery is unequivocally permitted and wish to deliver by the vaginal route.
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http://dx.doi.org/10.1515/JPM.2006.020DOI Listing
September 2006

Accumulation of paralytic shellfish toxins (PST) from the cyanobacterium Aphanizomenon issatschenkoi by the cladoceran Daphnia magna.

Toxicon 2004 Dec;44(7):773-80

Centro Interdisciplinar de Investigação Marinha e Ambiental, Rua dos Bragas 177-289, 4150-123 Porto, Portugal.

In order to access the effects of Paralytic Shellfish Toxins (PST) in freshwater environment, the accumulation of PST produced by the cyanobacteria Aphanizomenon issatschenkoi in juvenile Daphnia magna was investigated. D. magna was exposed to A. issatschenkoi cells (1.2 x 10(6) cells ml(-1)) for 6, 8, 12, 24 and 30 h and also to lyophilised material (1 mg ml(-1)) for 24h. Survival and somatic growth of the juvenile D. magna was investigated, as was the activity of the biotransformation enzyme system glutathione-S-transferases (GSTs). Between 643+/-65.35 and 1170+/-51.72 pmol PST ml(-1) were detected by HPLC-FLD in D. magna culture medium containing cells and 2745+/-64.61 pmol PST toxin ml(-1), in the medium containing lyophilised material. PST were detected in D. magna tissues in cells exposure (between 6.51 x 10(-2)+/-1.37 x 10(-2) and 3.78 x 10(-1)+/-1.15 x 10(-2)pmol PST animal(-1)). In D. magna exposed to lyophilised material the mean (+/-SD) PST concentration was found to be 6.96 x 10(-3) (+/-3.84 x 10(-3)) pmol PST animal(-1). Following exposure to 1.2 x 10(6) cells ml(-1)A. issatschenkoi fresh cells growth and survival of D. magna were reduced. D. magna exposed to the two A. issatschenkoi treatments (fresh cells and lyophilised material), showed a reduction in activity of the cytosolic glutathione-S-transferases (cGSTs). The results of this study indicate that D. magna can accumulate PST toxins and that the cyanobacterium A. issatschenkoi affects both the fitness and growth potential of juvenile D. magna.
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http://dx.doi.org/10.1016/j.toxicon.2004.08.006DOI Listing
December 2004

Accumulation and depuration of cyanobacterial paralytic shellfish toxins by the freshwater mussel Anodonta cygnea.

Aquat Toxicol 2004 Jul;68(4):339-50

Laboratório de Microbiologia e Ecotoxicologia, Instituto Nacional de Saúde Dr Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal.

The increasing frequency by which the production of paralytic shellfish toxins (PST) by freshwater bloom-forming cyanobacteria is being noticed world-wide raises the possibility of PST bioaccumulation by freshwater mussels. This study evaluates PST accumulation and depuration by the freshwater mussel Anodonta cygnea exposed over a 14-day period to high densities (mean = 1.4 x 10(9) cells1(-1), S.D. = 0.29 x 10(9) cellsl(-1)) of the toxic cyanobacterium Aphanizomenon issatschenkoi (corresponding to a mean toxin concentration of 25.5 nmol PSTl(-1), S.D. = 9.9 nmol PSTl(-1)). Mussels were subsequently detoxified either by starvation or by feeding on the non-toxic green-algae Ankistodesmus falcatus. Filter feeding activity and toxin uptake by the mussels were followed by cell counting and toxin analysis in water samples taken before and after each daily water renewal. The accumulation and depuration of PST as well as the anatomical distribution of toxins were monitored throughout the experiment by HPLC analysis of mussel extracts. Mussels fed the toxic cyanobacterium removed on average 65.3% of cells and 40.36% of total PST daily provided. Daily rates of cell clearance (% of initial) were negatively correlated with the amounts of PST daily provided (but not with the amount of cells). This suggests a negative effect of toxins on the feeding behaviour of mussels. Small amounts of toxins could be detected in the mussels after the second day of exposure, reaching a maximum of 26 microg PST100 g(-1) by day 7. The viscera contained the greatest proportion of toxins (78%) at the start of the toxification. However, increasing amounts of PST were found in the remaining tissues (gills, mantle and foot) over time. Toxins detected in the mussel extracts were the same provided in the dietary A. issatschenkoi. Nevertheless, mussels showed a higher proportion of saxitoxin and decarbomoylsaxitoxin and a lower proportion of gonyautoxin-5 than the fed cyanobacterium. Similar depuration efficiencies were observed among starved individuals (6.9% day(-1)) and those fed with A. falcatus (8.2% day(-1)) indicating that both treatments had comparable effects on toxin metabolism. Mussels showed a typical S shaped depuration kinetics curve consisting of a first short period of slow toxin decay followed by a rapid loss and a subsequent slower release of toxins. Trace to undetectable levels of PST were found in mussels after the 14-day depurating period. Although freshwater mussels are not widely consumed by humans, their capacity to accumulate PST points to the risk of PST propagation through the food chain of freshwater ecosystems via filter-feeding mussels.
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http://dx.doi.org/10.1016/j.aquatox.2004.04.001DOI Listing
July 2004
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