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Find video protocols related to scientific articles indexed in Pubmed.
Cytomegalovirus Infection in Patients Who Underwent Allogeneic Hematopoietic Stem Cell Transplantation in Portugal: A Five-Year Retrospective Review.
Biol. Blood Marrow Transplant.
PUBLISHED: 08-17-2014
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Cytomegalovirus (CMV) infection is 1 of the leading causes of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (aHSCT), mainly within the first 100 days after transplantation. We aimed to characterize CMV infection in a cohort of 305 patients with different malignancies undergoing aHSCT at the Portuguese Institute of Oncology of Porto between January 2008 and December 2012. In total, 184 patients (60.3%) developed CMV infection, mainly viral reactivations rather than primary infections (96.2% versus 3.8%, respectively). The majority of patients (166 of 184) developed CMV infection ?100 days after transplantation, with median time to infection of 29 days (range, 0 to 1285) and median duration of infection of 10 days (range, 2 to 372). Multivariate analysis revealed that CMV infection was more than 10-fold increased in donor (D)-/recipient (R)+ and D+/R+ (odds ratio [OR], 10.5; 95% confidence interval [CI], 4.35 to 25.4; P < .001) and in patients with mismatched or unrelated donors (OR, 2.54; 95% CI, 1.34 to 4.80; P = .004). Cox regression model showed that the risk of death was significantly increased in patients >38 years old (OR, 1.89; 95% CI, 1.14 to 3.12; P = .0137), who underwent transplantation with peripheral blood (OR, 3.02; 95% CI, 1.33 to 6.86; P = .008), with mismatched or unrelated donor (OR, 2.16; 95% CI, 1.48 to 3.13; P < .001), and who developed CMV infection (OR, 1.76; 95% CI, 1.07 to 2.90; P = .025). Moreover, patients who developed CMV infection had a significantly reduced median post-transplantation survival (16 versus 36 months; P = .002).
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[Carotid Atherosclerosis and White Matter Hypodensities: a Controversial Relationship.]
Acta Med Port
PUBLISHED: 04-21-2014
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Introduction: White matter hypodensities of presumed vascular origin, are recognized as an important cause of morbidity with established clinical and cognitive consequences. Nonetheless, many doubts remain on its physiopathology. Our goal is to clarify the potential role of carotid atherosclerosis and other vascular risk factors in the development of white matter hypodensities of presumed vascular origin.Material and Methods: We included patients that underwent CT brain scan and neurosonologic evaluation within a one-month period. Full assessment of vascular risks factors was performed. We seek to find independent associations between white matter hypodensities of presumed vascular origin, carotid intima-media thickness and vascular risk factors.Results: 472 patients were included, mean age was 67.32 (SD: 14.75), 274 (58.1%) were male. The independent predictors of white matter hypodensities of presumed vascular origin were age (OR: 1.067, 95% IC: 1.049 - 1.086, p < 0.001) and hypertension (OR: 1.726, 95% IC: 1.097 - 2.715, p = 0.018). No association was found between IMT (OR: 2.613, 95% IC: 0.886 - 7.708, p = 0.082) or carotid artery stenosis (OR: 1.021, 95% IC: 0.785 - 1.328, p = 0.877) and white matter hypodensities of presumed vascular origin.Discussion: Only age and hypertension proved to have an independent association with white matter hypodensities of presumed vascular origin. Carotid atherosclerosis, evaluated by IMT and the degree of carotid artery stenosis, showed no association with white matter hypodensities of presumed vascular origin. Since atherosclerosis is a systemic pathology, these results suggest that alternative mechanisms are responsible for the development of white matter hypodensities of presumed vascular origin.Conclusion: Age and hypertension seem to be the main factors in the development of white matter hypodensities of presumed vascular origin. No association was found between carotid atherosclerosis and white matter hypodensities of presumed vascular origin.
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Different locations but common associations in subcortical hypodensities of presumed vascular origin: cross-sectional study on clinical and neurosonologic correlates.
BMC Neurol
PUBLISHED: 02-03-2014
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Subcortical hypodensities of presumed vascular etiology (SHPVO) are a clinical, radiological and neuropathological syndrome with a still largely unexplained pathophysiology. Parallel to the clinical heterogeneity, there is also recognised cerebral topographical diversity with undetermined etiological implications. Our aim is to assess clinical and neurosonological predictors of SHPVO according to their location.
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Immunosuppression abrogates resistance of young rabbits to Rabbit Haemorrhagic Disease (RHD).
Vet. Res.
PUBLISHED: 01-21-2014
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Rabbit Haemorrhagic Disease (RHD) is caused by a calicivirus (RHDV) that kills 90% of infected adult European rabbits within 3 days. Remarkably, young rabbits are resistant to RHD. We induced immunosuppression in young rabbits by treatment with methylprednisolone acetate (MPA) and challenged the animals with RHDV by intramuscular injection. All of these young rabbits died within 3 days of infection due to fulminant hepatitis, presenting a large number of RHDV-positive dead or apoptotic hepatocytes, and a significant seric increase in cytokines, features that are similar to those of naïve adult rabbits infected by RHDV. We conclude that MPA-induced immunosuppression abrogates the resistance of young rabbits to RHD, indicating that there are differences in the innate immune system between young and adult rabbits that contribute to their distinct resistance/susceptibility to RHDV infection.
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Characterization of human papillomavirus genotypes and HPV-16 physical status in cervical neoplasias of women from northern Portugal.
Int J Gynaecol Obstet
PUBLISHED: 01-10-2014
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To determine human papillomavirus (HPV) genotypes and the physical status of HPV-16 DNA among women from northern Portugal with cervical lesions.
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MicroRNAs as biomarkers of cervical cancer development: a literature review on miR-125b and miR-34a.
Mol. Biol. Rep.
PUBLISHED: 01-09-2014
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MicroRNAs are non-coding RNAs with important functions in several biological processes, such as, regulation of cell cycle, immune response, inflammation, and apoptosis. In fact, deregulation and abnormal expression of these molecules is associated with human pathologies including cancer and several have already emerged as potential prognostic biomarkers in different neoplasias. miR-34a is directly regulated by p53 and acts as tumor suppressor while miR-125b plays a significant role in immune response and apoptosis. In cervical carcinogenesis, HPV proteins seem to interact with both miR-34a and miR-125b changing its expression and promoting persistent infection and cervical cancer development. In this review we describe the potential role of miR-125b and miR-34a in cervical carcinogenesis, including interaction with HPV and mechanism of deregulation. Additionally, their clinical applications in cervical cancer as prognostic/predictive biomarkers are also briefly discussed.
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Health professionals moving to… and from Portugal.
Health Policy
PUBLISHED: 05-12-2013
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The mobility of health professionals in the European Union is a phenomenon which policy-makers must take into account to provide the conditions to adjust for demand and supply of health services. This paper presents the case of Portugal, a country which at the same time imports and exports health workers. Since the early 1990s Portugal became a destination country receiving foreign health care professionals. This situation is now changing with the current economic situation as fewer immigrants come and more Portuguese emigrate. Foreigners coming to Portugal do so in part for similar reasons that bring Portuguese to want to emigrate, mainly the search for better work conditions and professional development opportunities. The emigration of Portuguese health professionals is also stimulated by the difficulty for recently graduated nurses, dentists and diagnostic and therapeutic technicians to find employment, low salaries in the public and private sectors, heavy workloads, remuneration not related to performance and poor career prospects. The paradoxes described in this study illustrate the consequences of the absence of a policy for the health professions. Strategies based on evidence, and on an integrated information system that captures the dynamic evolution of the workforce in health are not only necessary but also a good investment.
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Characterization of cytomegalovirus and epstein-barr virus infection in cervical lesions in Portugal.
J. Med. Virol.
PUBLISHED: 02-27-2013
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Infection by high-risk types of human papillomavirus (HPV) is considered necessary but not sufficient for the development of cervical cancer. Previous studies suggested that cytomegalovirus (CMV) and Epstein-barr virus (EBV) could be co-factors of HPV-associated carcinogenesis. The aim of this study was to characterize the prevalence of CMV and EBV and evaluate its association with the development cervical lesions in Portugal. The prevalence of CMV and EBV infections was determined by real-time PCR in 89 cervical samples from women with different histological lesions, who attended the Portuguese Institute of Oncology of Porto. This study revealed an overall prevalence of 4.5% for CMV and 10.1% for EBV. Age-stratified analysis revealed that CMV infection was present in individuals <30 and >60 years old, while EBV infection was present in all age groups. CMV was detected in 9.5% of low-grade lesions and in 22.2% of in situ/invasive carcinomas, while EBV infection was found in all different types of lesions. In addition, data revealed that CMV infection was associated with an increased risk of in situ/invasive carcinoma development (OR=1.28; P=0.035). The study reveals a low prevalence for both viruses; nevertheless, these results are important for knowledge on the shedding of EBV and CMV in cervical samples.
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Extensive FE-SEM/EDS, HR-TEM/EDS and ToF-SIMS studies of micron- to nano-particles in anthracite fly ash.
Sci. Total Environ.
PUBLISHED: 02-04-2013
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The generation of anthropogenic carbonaceous matter and mixed crystalline/amorphous mineral ultrafine/nano-particles in the 1 to 100 nm size range by worldwide coal power plants represents serious environmental problems due to their potential hazards. Coal fly ash (CFA) that resulted from anthracite combustion in a Portuguese thermal power plant was studied in this work. The physico-chemical characterization of ultrafine/nano-particles present in the CFA samples and their interaction with environment are the aim of this study. The methodologies applied for this work were field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy with energy dispersive X-ray spectroscopy (HR-TEM/EDS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Some hazardous volatile elements, C, N, S and Hg contents were also determined in the studied samples. Generally, the CFA samples comprise carbonaceous, glassy and metallic solid spheres with some containing mixed amorphous/crystalline phases. The EDS analysis coupled with the FE-SEM and HR-TEM observations of the fly ash particles with 100 to 0.1 nm demonstrates that these materials contain a small but significant proportion of encapsulated HVEs. In addition, the presence of abundant multi-walled carbon nanotubes (MWCNTs) and amorphous carbon particles, both containing hazardous volatile elements (HVEs), was also evidenced by the FE-SEM/EDS and HR-TEM/EDS analysis. A wide range of organic and inorganic compounds was determined by chemical maps obtained in ToF-SIMS analysis.
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Is Chlamydia trachomatis related to human papillomavirus infection in young women of southern European population? A self-sampling study.
Arch. Gynecol. Obstet.
PUBLISHED: 01-10-2013
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It is well established the role of human papillomavirus (HPV) in cervical cancer (CC) etiology. Chlamydia trachomatis (CT) infection seems to synergize with HPV in CC multistage process. The aim of this study was to assess the correlation of HPV and CT infection in young student women.
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Oncogenic HPV Types Infection in Adolescents and University Women from North Portugal: From Self-Sampling to Cancer Prevention.
J Oncol
PUBLISHED: 09-05-2011
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This study aimed to characterize the HPV infection status in adolescents and young university women in Portugal. The distribution of HPV genotypes was evaluated by PCR DNA genotyping after self-sampling collection from 435 women of exfoliated cervical cells using a commercial kit. We observed an overall frequency of HPV infection of 11.5%. Furthermore, HPV DNA prevalence was 16.6% in those young women that self-declared as sexually active. The more frequently detected HPV types were 31, 16, 53, and 61. Statistical analysis identified median age (OR = 3.56; P = 0.001), the number of lifetime sexual partners (OR = 4.50; P < 0.001), and years of sexual activity (OR = 2.36; P = 0.008) as risk factors for HPV acquisition. Hence, our study revealed that oncogenic HPV infection is common in young asymptomatic women Portuguese women, with a history of 2-5 sexual partners and over 2 year of sexual activity. Moreover, these results demonstrate that HPV detection performed in self-collected samples may be important to appraise better preventive strategies and to monitorize the influence of vaccination programmes within different populations.
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[Prevalence of respiratory symptoms in areas of the Federal District, Brazil].
Rev. Panam. Salud Publica
PUBLISHED: 08-11-2011
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The identification of individuals with respiratory symptoms (RS) is important for the early detection of tuberculosis. The aim of this study was to estimate the prevalence of RS in three administrative regions of the Federal District, Brazil. For this, we used the 30 by 7 cluster sampling technique proposed by the World Health Organization. Individuals with RS were defined as those aged 15 years or older living in the administrative regions of Estrutural, Itapoã, or Varjão and reporting a cough lasting at least 3 weeks at the date of the interview. The prevalence of RS was 5.7% in Estrutural and Varjão (95% CI: 2.4-9.0) and 4.8% in Itapoã (95%CI: 1.6-7.9), with a design effect close to 1.0. In Estrutural and Itapoã, fewer years of schooling, and in Itapoã and Varjão, lower income, were associated with RS. Cigarette smoking was associated with the presence of RS in all regions. The prevalence of RS in the three administrative regions investigated is consistent with that of other areas with a similar socioeconomic profile.
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Polycyclic aromatic hydrocarbons (PAHs) in burning and non-burning coal waste piles.
J. Hazard. Mater.
PUBLISHED: 07-08-2011
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The coal waste material that results from Douro Coalfield exploitation was analyzed by gas chromatography with mass spectrometry (GC-MS) for the identification and quantification of the 16 polycyclic aromatic hydrocarbons (PAHs), defined as priority pollutants. It is expected that the organic fraction of the coal waste material contains PAHs from petrogenic origin, and also from pyrolytic origin in burning coal waste piles. The results demonstrate some similarity in the studied samples, being phenanthrene the most abundant PAH followed by fluoranthene and pyrene. A petrogenic contribution of PAHs in unburned samples and a mixture of PAHs from petrogenic and pyrolytic sources in the burning/burnt samples were identified. The lowest values of the sum of the 16 priority PAHs found in burning/burnt samples and the depletion LMW PAHs and greater abundance of HMW PAHs from the unburned coal waste material relatively to the burning/burnt material demonstrate the thermal transformation attributed to the burning process. The potential environmental impact associated with the coal waste piles are related with the release of petrogenic and pyrolytic PAHs in particulate and gaseous forms to soils, sediments, groundwater, surface water, and biodiversity.
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Epigenetics and senescence: learning from the INK4-ARF locus.
Biochem. Pharmacol.
PUBLISHED: 05-19-2011
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Cellular senescence is the biological consequence of aging. However, the same mechanisms that provoke senescence during aging have been proven to act in tumor suppression and thus to occur in premalignant cells. All the diverse aspects of the senescent phenotype, as are observed for many other cell fates, arise from alterations of the chromatin architecture. Relatively little is known overall about the changes in chromatin structure, and which regulatory networks are implicated in these. Major insight into the epigenetic contributions to senescence has been gained by studying the regulation of the INK4-ARF locus. Activation of the tumor suppressors encoded by this locus leads to an irreversible cell cycle exit. Importantly, epigenetic alterations at this locus have been associated with the onset of cancer. Here we discuss the recent findings that link epigenetics to the senescence pathway.
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High-throughput total cupric ion reducing antioxidant capacity of biological samples determined using flow injection analysis and microplate-based methods.
Anal Sci
PUBLISHED: 05-12-2011
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High-throughput cupric ion reducing antioxidant capacity (CUPRAC) methods were developed for assessment of total antioxidant capacity (TAC) in urine and serum, based on reduction of Cu(II)-neocuproine complex to highly colored Cu(I)-neocuproine complex, measured spectrophotometrically at 450 nm. The reaction time was significantly reduced from 30 to 4 min by application of a calibration compound (uric acid) with kinetic behavior similar to that shown by urine samples. The method was implemented in a microformat (96 well plates) and also in an automatic fashion (flow injection analysis, FIA). A determination throughput value of 288 h(-1) (microplate method) or of 15 h(-1) (automatic FIA) was attained. Application of both methods to human serum (SRM 909b, level I) and urines (n = 9) provided TAC values in agreement with those of the end-point batch method.
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Determination of the scavenging capacity against reactive nitrogen species by automatic flow injection-based methodologies.
Methods Mol. Biol.
PUBLISHED: 05-06-2011
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Automatic flow-based systems have been applied to assay scavenging capacity against reactive oxygen and nitrogen species, providing analytical tools which can cope with different types and large number of samples. In the present chapter, a flow injection analysis procedure is described for the assessment of peroxynitrite scavenging. A sequential injection analysis procedure is also described for determining the scavenging capacity against the nitric oxide radical. For both systems, reaction between putative antioxidants and the reactive species of nitrogen takes place inside the flow conduits before addition of luminol and further detection of remaining reactive species by chemiluminescence.
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Standard operation protocol for analysis of lipid hydroperoxides in human serum using a fully automated method based on solid-phase extraction and liquid chromatography-mass spectrometry in selected reaction monitoring.
J Chromatogr A
PUBLISHED: 03-30-2011
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Standard operating procedures (SOPs) are of paramount importance in the analytical field to ensure the reproducibility of the results obtained among laboratories. SOPs gain special interest when the aim is the analysis of potentially unstable compounds. An SOP for analysis of lipid hydroperoxides (HpETEs) is here reported after optimization of the critical steps to be considered in their analysis in human serum from sampling to final analysis. The method is based on automated hyphenation between solid-phase extraction (SPE) and liquid chromatography-mass spectrometry (LC-MS). The developed research involves: (i) optimization of the SPE and LC-MS steps with a proper synchronization; (ii) validation of the method-viz. accuracy study (estimated as 86.4% as minimum value), evaluation of sensitivity and precision, which ranged from 2.5 to 7.0 ng/mL (0.25-0.70 ng on column) as quantification limit and precision below 13.2%), and robustness study (reusability of the cartridge for 5 times without affecting the accuracy and precision of the method); (iii) stability study, involving freeze-thaw stability, short-term and long-term stability and stock solution stability tests. The results thus obtained allow minimizing both random and systematic variation of the metabolic profiles of the target compounds by correct application of the established protocol.
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Inter-rater concordance study of the PASI (Psoriasis Area and Severity Index).
An Bras Dermatol
PUBLISHED: 12-15-2010
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Developed in 1978, the PASI (Psoriasis Area and Severity Index) is a method to rate psoriasis severity. Since then, it has been criticized for being extremely long, complex and for yielding significantly divergent interpretations.
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Transcriptional activation of polycomb-repressed genes by ZRF1.
Nature
PUBLISHED: 10-12-2010
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Covalent modification of histones is fundamental in orchestrating chromatin dynamics and transcription. One example of such an epigenetic mark is the mono-ubiquitination of histones, which mainly occurs at histone H2A and H2B. Ubiquitination of histone H2A has been implicated in polycomb-mediated transcriptional silencing. However, the precise role of the ubiquitin mark during silencing is still elusive. Here we show in human cell lines that ZRF1 (zuotin-related factor 1) is specifically recruited to histone H2A when it is ubiquitinated at Lys?119 by means of a novel ubiquitin-interacting domain that is located in the evolutionarily conserved zuotin domain. At the onset of differentiation, ZRF1 specifically displaces polycomb-repressive complex 1 (PRC1) from chromatin and facilitates transcriptional activation. A genome-wide mapping of ZRF1, RING1B and H2A-ubiquitin targets revealed its involvement in the regulation of a large set of polycomb target genes, emphasizing the key role ZRF1 has in cell fate decisions. We provide here a model of the molecular mechanism of switching polycomb-repressed genes to an active state.
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Identification of nanominerals and nanoparticles in burning coal waste piles from Portugal.
Sci. Total Environ.
PUBLISHED: 08-02-2010
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A range of carbon nanoparticles, agglomerates and mineral phases have been identified in burning coal waste pile materials from the Douro Coalfield of Portugal, as a basis for identifying their potential environmental and human health impacts. The fragile nature and fine particle size of these materials required novel characterization methods, including energy-dispersive X-ray spectrometry (EDS), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM) techniques. The chemical composition and possible correlations with morphology of the nanominerals and associated ultra-fine particles have been evaluated in the context of human health exposure, as well as in relation to management of such components in coal-fire environments.
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Fully automatic flow method for the determination of scavenging capacity against nitric oxide radicals.
Anal Bioanal Chem
PUBLISHED: 04-12-2010
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In the present work, a fluorimetric automatic method based on multisyringe flow injection analysis (MSFIA) was developed for in vitro evaluation of scavenging capacity against nitric oxide (NO) using 4,5-diaminofluorescein (DAF-2) as an NO-selective fluorogenic probe. The MSFIA manifold was assembled to perform the in-line generation of NO and the competitive reaction of putative scavenger molecules and DAF-2 with NO at conditions close to those found in vivo regarding temperature (37 degrees C), pH (7.4), and concentration of NO (less than 1 microM). This approach allowed the evaluation of scavenging capacity against NO by endogenous antioxidant molecules, pharmaceutical compounds, and human plasma. IC(50) values were calculated for rutin (1.30 +/- 0.02 microM, positive control), cysteine (321 +/- 8 microM), reduced glutathione (1106 +/- 93 microM), uric acid (134 +/- 12 microM), dipyrone (1.36 +/- 0.06 microM), and captopril (363 +/- 28 microM). A high degree of automation was attained as the successive dilution of antioxidant standard solutions required for IC(50) assessment was performed automatically, in a dilution chamber placed in the flow system. A determination throughput of 16 h(-1) and a good precision were attained (relative standard deviation between 1.6 and 9.0%), fostering the application of the proposed method to routine/screening analysis of scavenging capacity against NO.
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Hydrogen peroxide, antioxidant compounds and biological targets: an in vitro approach for determination of scavenging capacity using fluorimetric multisyringe flow injection analysis.
Talanta
PUBLISHED: 03-18-2010
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In the present work, an automatic method based on multisyringe flow injection analysis (MSFIA) was developed for determination of scavenging capacity against H(2)O(2) using a non-enzymatic fluorimetric assay for H(2)O(2) detection based on the formation of europium-tetracycline-H(2)O(2) complex. The MSFIA-fluorimetric methodology was developed to perform in-line the scavenging reaction of H(2)O(2) prior to reaction of the remaining H(2)O(2) with the fluorescent probe, using conditions close to those found in vivo regarding pH (6.9), temperature (37 degrees C) and H(2)O(2) concentration (25microM). This approach allowed the evaluation of scavenging capacity against H(2)O(2) in a non-competitive (antioxidant+H(2)O(2)) or a competitive (antioxidant+H(2)O(2)+biological target) scheme. Using the first strategy, IC(50) values determined for the antioxidant compounds glutathione reduced (1191+/-46microM) and pyruvate (446+/-49microM) were lower than those obtained for biological targets such as cysteine (2616+/-182microM), taurine (359+/-38mM) and adenine (2224+/-214microM), indicating that reactivity towards H(2)O(2) was higher for antioxidant compounds than for biological targets. However, when a competitive scheme was applied, the scavenging effectiveness against H(2)O(2) depended on the biological molecule present, showing that antioxidant assessment should also take into consideration the concomitant reactivity of biological molecules or structures that are prone to oxidative damage.
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Spectrophotometric FIA methods for determination of hydrogen peroxide: application to evaluation of scavenging capacity.
Talanta
PUBLISHED: 02-12-2009
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The determination of hydrogen peroxide (H(2)O(2)) and the evaluation of scavenging capacity against this species were performed using five colorimetric reactions, which were adapted to flow injection analysis. The reactions chosen were based on the oxidation of iodide (I(-) method), on the formation of titanium-peroxide complex (TiP method), on the formation of titanium-xylenol orange-peroxide complex (TiXoP method), on the oxidation of 3,3,5,5-tetramethylbenzidine (TMB method) and on the co-oxidation of phenol-4-sulfonic acid and 4-aminoantipyrine (PSA/4-AAP method). The operational conditions were studied in order to improve the sensitivity of each method. Concerning to the method sensitivity, the ranking order was TMB method>I(-) method>TiXoP method approximately PSA/4-AAP method>TiP method. All methods showed an excellent repeatability (RSD<2%) and, except for I(-) method, relative deviations from the reference method were <1.9%. The FIA manifolds were adapted to perform the determination of scavenging capacity against H(2)O(2) and glutathione (GSH) was applied as model compound. TiP and TiXoP methods were not suitable as no inhibition or an increase of analytical signal was attained. PSA/4-AAP method was chosen for further application to dietary phenolics and pharmaceutical compounds, providing IC(50) values for those compounds that are fast reacting antioxidants.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.