Título del artículo:

Risk of bias and confounding of observational studies of Zika virus infection: A scoping review of research protocols

Introduction Given the severity and impact of the current Zika virus (ZIKV) outbreak in the Americas, numerous countries have rushed to develop research studies to assess ZIKV and its potential health consequences. In an effort to ensure that studies are comprehensive, both internally and externally valid, and with reliable results, the World Health Organization, the Pan American Health Organization, Institut Pasteur, the networks of Fiocruz, the Consortia for the Standardization of Influenza Seroepidemiology (CONSISE) and the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) have generated six standardized clinical and epidemiological research protocols and questionnaires to address key public health questions on ZIKV. Methods We conducted a systematic search of ongoing study protocols related to ZIKV research. We analyzed the content of protocols of 32 cohort studies and 13 case control studies for systematic bias that could produce erroneous results. Additionally we aimed to characterize the risks of bias and confounding in observational studies related to ZIKV and to propose ways to minimize them, including the use of six newly standardized research protocols. Results Observational studies of ZIKV face an array of challenges, including measurement of exposure and outcomes (microcephaly and Guillain-Barré Syndrome). Potential confounders need to be measured where known and controlled for in the analysis. Selection bias due to non-random selection is a significant issue, particularly in the case-control design, and losses to follow-up is equally important for the cohort design. Conclusion Observational research seeking to answer key questions on the ZIKV should consider these restrictions and take precautions to minimize bias in an effort to provide reliable and valid results. Utilization of the standardized research protocols developed by the WHO, PAHO, Institut Pasteur, and CONSISE will harmonize the key methodological aspects of each study design to minimize bias at different stages of the study. Biases need to be considered by researchers implementing the standardized protocols as well as by users of observational epidemiological studies of ZIKV.

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PLoS ONE

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Global mortality variations in patients with heart failure: results from the International Congestive Heart Failure (INTER-CHF) prospective cohort study

Background Most data on mortality and prognostic factors in patients with heart failure come from North America and Europe, with little information from other regions. Here, in the International Congestive Heart Failure (INTER-CHF) study, we aimed to measure mortality at 1 year in patients with heart failure in Africa, China, India, the Middle East, southeast Asia and South America; we also explored demographic, clinical, and socioeconomic variables associated with mortality. Methods We enrolled consecutive patients with heart failure (3695 [66%] clinic outpatients, 2105 [34%] hospital in patients) from 108 centres in six geographical regions. We recorded baseline demographic and clinical characteristics and followed up patients at 6 months and 1 year from enrolment to record symptoms, medications, and outcomes. Time to death was studied with Cox proportional hazards models adjusted for demographic and clinical variables, medications, socioeconomic variables, and region. We used the explained risk statistic to calculate the relative contribution of each level of adjustment to the risk of death. Findings We enrolled 5823 patients within 1 year (with 98% follow-up). Overall mortality was 16·5%: highest in Africa (34%) and India (23%), intermediate in southeast Asia (15%), and lowest in China (7%), South America (9%), and the Middle East (9%). Regional differences persisted after multivariable adjustment. Independent predictors of mortality included cardiac variables (New York Heart Association Functional Class III or IV, previous admission for heart failure, and valve disease) and non-cardiac variables (body-mass index, chronic kidney disease, and chronic obstructive pulmonary disease). 46% of mortality risk was explained by multivariable modelling with these variables; however, the remainder was unexplained. Interpretation Marked regional differences in mortality in patients with heart failure persisted after multivariable adjustment for cardiac and non-cardiac factors. Therefore, variations in mortality between regions could be the result of health-care infrastructure, quality and access, or environmental and genetic factors. Further studies in large, global cohorts are needed. Funding The study was supported by Novartis.

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The Lancet Global Health

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The Relationship between Socioeconomic Status, Family Income, and Measures of Muscular and Cardiorespiratory Fitness in Colombian Schoolchildren

Objective To determine the associations between socioeconomic status (SES) and physical fitness in a sample of Colombian youth. Study design Prueba SER is cross-sectional survey of schoolchildren in Bogota, Colombia. Mass, stature, muscular fitness (standing long-jump, handgrip), and cardiorespiratory fitness (20-m shuttle run) were measured in 52 187 schoolchildren 14-16 years of age. Area-level SES was categorized from 1 (very low) to 4 (high) and parent-reported family income was categorized as low, middle, or high. Results Converting measures into z scores showed stature, muscular, and cardiorespiratory fitness were significantly (z = 0.3-0.7) below European values. Children in the mid- and high SES groups jumped significantly further than groups with very low SES. Differences were independent of sex but became nonsignificant when adjusted for anthropometric differences. Participants in the mid-SES and high-SES groups had better handgrip scores when adjusted for body dimension. There were, however, no significant between-group differences in cardiorespiratory fitness, which was strongly clustered by school and significantly greater in students from private schools. Conclusions Area-level SES is associated with measures of muscular fitness in Colombian schoolchildren. These associations were largely explained by the large differences in body dimensions observed between SES groups. When area-level SES is considered, there was no evidence that family income influenced fitness. The clustering of outcomes reaffirms the potential importance of schools and area-level factors in promoting fitness through opportunities for physical activity. Interventions implemented in schools, can improve academic attainment; a factor likely to be important in promoting the social mobility of children from poorer families.

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Journal of Pediatrics

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Cyclic Vomiting Syndrome is characterized by altered functional brain connectivity of the insular cortex: A cross-comparison with migraine and healthy adults

Cyclic Vomiting Syndrome (CVS) has been linked to episodic migraine, yet little is known about the precise brain-based mechanisms underpinning CVS, and whether these associated conditions share similar pathophysiology. We investigated the functional integrity of salience (SLN) and sensorimotor (SMN) intrinsic connectivity networks in CVS, migraine and healthy controls using brain functional Magnetic Resonance Imaging. CVS, relative to both migraine and controls, showed increased SLN connectivity to middle/posterior insula, a key brain region for nausea and viscerosensory processing. In contrast, this same region showed diminished SMN connectivity in both CVS and migraine. These results highlight both unique and potentially shared pathophysiology between these conditions, and suggest a potential target for therapeutics in future studies.

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Neurogastroenterology and Motility

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DNA secondary structure formation by DNA shuffling of the conserved domains of the Cry protein of Bacillus thuringiensis

Background: The Cry toxins, or δ-endotoxins, are a diverse group of proteins produced by Bacillus thuringiensis. While DNA secondary structures are biologically relevant, it is unknown if such structures are formed in regions encoding conserved domains of Cry toxins under shuffling conditions. We analyzed 5 holotypes that encode Cry toxins and that grouped into 4 clusters according to their phylogenetic closeness. The mean number of DNA secondary structures that formed and the mean Gibbs free energy Δ G $$ \\left(\\overline(\\varDelta G)\\right) $$ were determined by an in silico analysis using different experimental DNA shuffling scenarios. In terms of spontaneity, shuffling efficiency was directly proportional to the formation of secondary structures but inversely proportional to ΔG. Results: The results showed a shared thermodynamic pattern for each cluster and relationships among sequences that are phylogenetically close at the protein level. The regions of the cry11Aa, Ba and Bb genes that encode domain I showed more spontaneity and thus a greater tendency to form secondary structures (<ΔG). In the region of domain III; this tendency was lower (>ΔG) in the cry11Ba and Bb genes. Proteins that are phylogenetically closer to Cry11Ba and Cry11Bb, such as Cry2Aa and Cry18Aa, maintained the same thermodynamic pattern. More distant proteins, such as Cry1Aa, Cry1Ab, Cry30Aa and Cry30Ca, featured different thermodynamic patterns in their DNA. Conclusion: These results suggest the presence of thermodynamic variations associated to the formation of secondary structures and an evolutionary relationship with regions that encode highly conserved domains in Cry proteins. The findings of this study may have a role in the in silico design of cry gene assembly by DNA shuffling techniques.

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BMC Biophysics

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Technological surveillance of aromatic species: From research to the consolidation of the productive chain in Colombia

The sector of aromatic, medicinal and seasoning herbs brings together a wide variety of native and introduced species with agroindustrial potential. In order to contribute to the technological assessment of the sector in Colombia and provide elements of strategic planning towards higher levels of development and internationalization. We prioritized certain aromatic species in this article and a technological surveillance was made during 2004-2014. A searching scientific articles and patents was made in eight national, iberoamericanand worldwide databases according prioritized issues. Data processing was performed using Microsoft Excel, EndNote, Vantage Point (2014) Thomson Data Analyzer programs. At National level, the planting material and breeding has been the main researched topic; whereas in iberoamerica and the world was biocidal effect. The leading countries in research on the monitored aromatic plants were Brazil, Colombia and Cuba. Internationally, the scientific leaders according to PubMed and Scopus were India, USA, Brazil and Colombia. The global trend in the field of patents has increased, whose main focus is: \"Current needs of life\". This technological surveillance gives an overview of developments and trends in research and technological development in different subject areas within the aromatic plants, besides identifying possible allied research and the scientific production trends over time.

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Corpoica Ciencia y Tecnologia Agropecuaria

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Strength and endurance training reduces the loss of eccentric hamstring torque observed after soccer specific fatigue

Objectives To investigate the effect of two hamstring training protocols on eccentric peak torque before and after soccer specific fatigue. Participants Twenty-two university male soccer players. Design Isokinetic strength tests were performed at 60°/s pre and post fatigue, before and after 2 different training interventions. A 45-min soccer specific fatigue modified BEAST protocol (M-BEAST) was used to induce fatigue. Players were randomly assigned to a 4 week hamstrings conditioning intervention with either a maximum strength (STR) or a muscle endurance (END) emphasis. Main outcome measures The following parameters were evaluated: Eccentric peak torque (EccPT), angle of peak torque (APT), and angle specific torques at knee joint angles of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° and 90°. Results There was a significant effect of the M-BEAST on the Eccentric torque angle profile before training as well as significant improvements in post-fatigue torque angle profile following the effects of both strength and muscle endurance interventions. Conclusions Forty-five minutes of simulated soccer activity leads to reduced eccentric hamstring torque at longer muscle lengths. Short-term conditioning programs (4-weeks) with either a maximum strength or a muscular endurance emphasis can equally reduce fatigue induced loss of strength over this time period.

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Physical Therapy in Sport

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Analysis of the structure of the labour market in Colombia: A gender study based on multiple correspondence

In spite of the increasing education level and labour participation, several studies conclude that working conditions differ by gender in Colombia. This study based on multiple correspondence analysis applied to data from the Household Integrated Sample Survey in two different periods, 2007 and 2014, is aimed at studying the Colombian labour market segmentation by gender using social perceptual maps that facilitate the comparison of the general structure of the markets and their evolution over time. The results support the thesis of labour market segmentation, with clear differences in wages and in sectors and conditions of employment, as well as a delay in the evolution of the women labour market.

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Cuadernos de Economia

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Not everything is Zika: Congenital toxoplasmosis, still prevalent in Colombia?

Congenital toxoplasmosis continues to be a public health threat. Even existing guidelines, publicly known, its implementation and lack of appropriate interpretation of serological tests in pregnancy is often observed. This leds to failure in opportunities for positive and known interventions to decrease the fetal risk due to Toxoplasma gondii infection. We reported herein a case series, with variable neurological and systemic compromise (respiratory distress, hepatosplenomegaly, enterocolitis, brain calcifications, thrombocytopenia, ascites, shock), even fatal, calling for awareness about the fact that despite the Zika epidemics in 2015-2016 in Brazil, Colombia and other countries, precisely toxoplasmosis, is a differential diagnosis still prevalent in these territories, that can leds to severe consequences, with neurological disability and risk of ocular damage, even lately. Additionally, with varieties of T. gondii with more aggressive patterns in Latin America, which make worse those cases, including also a higher risk of death.

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Revista Peruana de Medicina Experimental y Salud Publica

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Performance and Intellectual Capital: How Enablers Drive Value Creation in Organisations

The main aim of this study is to establish the relationships between diverse research fields that academics traditionally address separately. Specifically, this paper explores the links between the resource-based view, intellectual capital and knowledge creation. To achieve this, we developed a novel theoretical model of relationships and tested this model empirically. We quantitatively test this model using data from firms in the Spanish biotechnology sector. The main practical implication is the intense relationship between intellectual capital, performance and the mediating variables. The model indicates the existence of 10 useful channels through which to direct efforts to improve organisational performance. We define a theoretical relational model between these fields, thus marking an innovation in the subject-specific literature because of the inclusion of intermediate or mediating variables, and their relationship with organisational performance. Copyright © 2017 John Wiley & Sons, Ltd.

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Knowledge and Process Management

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Segment scale typology for colombian andean rivers

This paper presents a method for establishing segment scale typology for the Andean rivers of Colombia. The method incorporates physical and ecological aspects and combines inferences of structural stability and metabolic activity. The classification of river segments is based on the assignment of two non-dimensional descriptors. The first descriptor involves aspects related to structural stability of the channel, whereas the second descriptor includes factors that affect the metabolic activity of planktonic communities in the water column and biotic communities on the bed. Each descriptor can adopt values that are divided into two categories, high and low. Both descriptors are organized orthogonally. A bidimensional 2 × 2 matrix is created, where the x-axis represents the current structural stability of the channel and the y-axis represents the metabolic activity. A case study that combines a set of thematic layers using GIS is presented for the Cundinamarca region in Colombia. Most of the river segments (97%) in Cundinamarca correspond to type 2 or 4. We provide data from macroinvertebrate samples to compare the obtained types with the actual biological communities present in the region. This method, which can be useful for scientists, managers and water planners, compares similarities and differences between water body systems, compiles basic information in a brief and clear manner and locates monitoring and reference sites for bioassessment studies.

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Ecohydrology and Hydrobiology

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Developing consensus measures for global programs: Lessons from the Global Alliance for Chronic Diseases Hypertension research program

Background: The imperative to improve global health has prompted transnational research partnerships to investigate common health issues on a larger scale. The Global Alliance for Chronic Diseases (GACD) is an alliance of national research funding agencies. To enhance research funded by GACD members, this study aimed to standardise data collection methods across the 15 GACD hypertension research teams and evaluate the uptake of these standardised measurements. Furthermore we describe concerns and difficulties associated with the data harmonisation process highlighted and debated during annual meetings of the GACD funded investigators. With these concerns and issues in mind, a working group comprising representatives from the 15 studies iteratively identified and proposed a set of common measures for inclusion in each of the teams\' data collection plans. One year later all teams were asked which consensus measures had been implemented. Results: Important issues were identified during the data harmonisation process relating to data ownership, sharing methodologies and ethical concerns. Measures were assessed across eight domains; demographic; dietary; clinical and anthropometric; medical history; hypertension knowledge; physical activity; behavioural (smoking and alcohol); and biochemical domains. Identifying validated measures relevant across a variety of settings presented some difficulties. The resulting GACD hypertension data dictionary comprises 67 consensus measures. Of the 14 responding teams, only two teams were including more than 50 consensus variables, five teams were including between 25 and 50 consensus variables and four teams were including between 6 and 24 consensus variables, one team did not provide details of the variables collected and two teams did not include any of the consensus variables as the project had already commenced or the measures were not relevant to their study. Conclusions: Deriving consensus measures across diverse research projects and contexts was challenging. The major barrier to their implementation was related to the time taken to develop and present these measures. Inclusion of consensus measures into future funding announcements would facilitate researchers integrating these measures within application protocols. We suggest that adoption of consensus measures developed here, across the field of hypertension, would help advance the science in this area, allowing for more comparable data sets and generalizable inferences.

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Globalization and Health

Título del artículo:

Cartas al editor en investigación medica

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Medwave

Título del artículo:

Prevalence and molecular epidemiology of Canine parvovirus 2 in diarrheic dogs in Colombia, South America: A possible new CPV-2a is emerging?

Since its identification in 1978, Canine parvovirus type 2 (CPV-2) has been considered a pathogen of great importance in the canine population because it causes severe enteritis with high mortality rates in pups. CPV-2 is a virus belonging to the family Parvoviridae. Currently, there are three described antigenic variants (CPV-2a, CPV-2b, and CPV-2c). CPV-2c is an emerging virus that is seen as a global health hazard. The objective of this work was to confirm the presence of CPV-2 in dogs with acute gastroenteritis compatible with parvovirus and to molecularly characterize the antigenic variants circulating in two regions of Colombia. An analytical cross-sectional study was conducted with fecal samples collected from 71 dogs showing signs of acute diarrhea. The samples were processed and polymerase chain reaction (PCR), restriction fragment length polymorphism analysis (RFLP), sequencing and phylogenetic analysis was performed to detect and characterize CPV. A total of 70.42% of the individuals were confirmed positive for CPV-2. Statistically differences were found in the presentation of CPV-2 between the evaluated regions. Phylogenetic analyses confirmed the presence of the antigenic variants CPV-2a/2b. Moreover, we found the presence of two conserved substitutions Asn428Asp and Ala514Ser in the VP2 protein suggesting the presence of a possible new CPV-2a variant circulating in Colombia. This study demonstrates the importance of the CPV 2a/2b in the region and highlights the importance of performing molecular studies for the early detection of new antigenic variants of CPV-2.

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Veterinary Microbiology

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Mapping of enkephalins and adrenocorticotropic hormone in the squirrel monkey brainstem

An immunocytochemical technique has been used to study for the first time the distribution of fibers and cell bodies containing leucine–enkephalin (leu-enk), methionine–enkephalin (met-enk) or adrenocorticotropic hormone (ACTH) in the whole brainstem of the squirrel monkey Saimiri sciureus. Cell bodies containing leu-enk or met-enk were found in the superior colliculus and the formatio reticularis tegmenti mesencephali, respectively. No immunoreactive cell bodies containing ACTH were observed. Leu-enk-immunoreactive fibers were observed in 40 brainstem nuclei/tracts/regions, fibers containing met-enk were found in 38 brainstem nuclei/tracts/regions and fibers containing ACTH were found in 26 nuclei/tracts/regions. In the latter case, the density of immunoreactive fibers was always low. A high/moderate density of leu-enk- or met-enk-immunoreactive fibers were found in 18 and 16 brainstem nuclei/tracts/regions, respectively. The distribution of immunoreactive fibers containing leu-enk or met-enk was quite similar, with both leu-enk and met-enk observed in 82.5 % of the squirrel monkey brainstem nuclei/tracts/regions. This relationship is less marked for met-enk and ACTH (60.5 %) and even lower for leu-enk and ACTH (52.5 %). In 42.5 % of the nuclei/tracts/regions of the squirrel monkey brainstem (colliculus superior, substantia grisea centralis, nucleus interpeduncularis, nucleus tractus spinalis nervi trigemini, nucleus tractus solitarii, nucleus parabrachialis, formatio reticularis, substantia nigra), we observed fibers containing all three neuropeptides. The widespread distribution reported here suggests that enkephalins and ACTH can be involved in several physiological functions. The distribution of the immunoreactive fibers reported here is quite similar to that previously reported for enkephalins and ACTH in Macaca species and humans.

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Anatomical Science International

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Complexity Variability Assessment of Nonlinear Time-Varying Cardiovascular Control

The application of complex systems theory to physiology and medicine has provided meaningful information about the nonlinear aspects underlying the dynamics of a wide range of biological processes and their disease-related aberrations. However, no studies have investigated whether meaningful information can be extracted by quantifying second-order moments of time-varying cardiovascular complexity. To this extent, we introduce a novel mathematical framework termed complexity variability, in which the variance of instantaneous Lyapunov spectra estimated over time serves as a reference quantifier. We apply the proposed methodology to four exemplary studies involving disorders which stem from cardiology, neurology and psychiatry: Congestive Heart Failure (CHF), Major Depression Disorder (MDD), Parkinson\'s Disease (PD), and Post-Traumatic Stress Disorder (PTSD) patients with insomnia under a yoga training regime. We show that complexity assessments derived from simple time-averaging are not able to discern pathology-related changes in autonomic control, and we demonstrate that between-group differences in measures of complexity variability are consistent across pathologies. Pathological states such as CHF, MDD, and PD are associated with an increased complexity variability when compared to healthy controls, whereas wellbeing derived from yoga in PTSD is associated with lower time-variance of complexity.

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Scientific Reports

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Analysis of spatial mobility in subjects from a dengue endemic urban locality in Morelos State, Mexico

Introduction Mathematical models and field data suggest that human mobility is an important driver for Dengue virus transmission. Nonetheless little is known on this matter due the lack of instruments for precise mobility quantification and study design difficulties. Materials and methods We carried out a cohort-nested, case-control study with 126 individuals (42 cases, 42 intradomestic controls and 42 population controls) with the goal of describing human mobility patterns of recently Dengue virus-infected subjects, and comparing them with those of noninfected subjects living in an urban endemic locality. Mobility was quantified using a GPSdata logger registering waypoints at 60-second intervals for a minimum of 15 natural days. Results Although absolute displacement was highly biased towards the intradomestic and peridomestic areas, occasional displacements exceeding a 100-Km radius from the center of the studied locality were recorded for all three study groups and individual displacements were recorded traveling across six states from central Mexico. Additionally, cases had a larger number of visits out of the municipality?s administrative limits when compared to intradomestic controls (cases: 10.4 versus intradomestic controls: 2.9, p = 0.0282). We were able to identify extradomestic places within and out of the locality that were independently visited by apparently non-related infected subjects, consistent with houses, working and leisure places. Conclusions Results of this study show that human mobility in a small urban setting exceeded that considered by local health authority\'s administrative limits, and was different between recently infected and non-infected subjects living in the same household. These observations provide important insights about the role that human mobility may have in Dengue virus transmission and persistence across endemic geographic areas that need to be taken into account when planning preventive and control measures. Finally, these results are a valuable reference when setting the parameters for future mathematical modeling studies.

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PLoS ONE

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Differential anti-proliferative effect on K562 leukemia cells of Lippia alba (Verbenaceae) essential oils produced under diverse growing, collection and extraction conditions

Lippia alba (Verbenaceae Family) is an aromatic shrub native to Latin America, with recognized medicinal properties and a well-known high phenotypical plasticity in response to environmental factors. In order to identify the parameters that potentiate its in vitro anti-proliferative effect on human leukemia cells (K562), a matrix was designed for the production of 76 essential oils (EOs) with variations in plant growing season, harvested part from the plant, and preservation and distillation material conditions. The results show that EOs obtained from the same L. alba chemotype (Citral or Carvone), but acquired under different environmental or extraction conditions, presented significant differences in their primary components, oil yield, and cytotoxic activity on K562 cells. Citral EOs produced under diverse conditions displayed a cytotoxic effect on tumour cells ranging from 54 to 95% (IS 1.8–8.6) and IC50 from 13 to 38.8 μg/mL. The differences in antiproliferative activity were significantly correlated with variations in the β-caryophyllene oxide concentration. These results show the value of using standardized production conditions for the commercial utilization of L. alba EOs.

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Industrial Crops and Products

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Muscle strength is associated with lower diastolic blood pressure in schoolchildren

Cardiorespiratory fitness (CRF) provides protection against the elevated blood pressure in overweight youth. Less is known regarding any similar protective effect of muscular fitness. We investigated how handgrip strength, an easy to implement measure of muscular strength, interacted with CRF and BMI to determine blood pressure in youth. We measured systolic (SBP) and diastolic (DBP) blood pressure, handgrip strength (HG), CRF and body mass index (BMI) in n = 7329 10–16 year-olds (47% girls). We defined elevated blood pressure as > 91st percentile and Good HG as > 33rd percentile. Participants were classified as Fit or Unfit and as Normal or Overweight/Obese based on international standards. The prevalence of elevated SBP was 23%, and 44% of participants had elevated DBP. In unfit participants Good HG was associated with lower SBP (z = 0.41 (95%CI: 0.20–0.61) and DBP (z = 0.29 (95%CI: 0.12–0.47). In Overweight/Obese participants, DBP was z = 0.24 (95%CI: 0.14–0.34) lower in the Good (versus Low) HG group. Overweight/Obese participants with Good HG also had a 32% lower risk of elevated DBP (OR: 0.68, 95%CI: 0.57–0.82). This association was attenuated but remained important after adjusting for BMI (20% risk reduction, OR: 0.80, 95%CI: 0.63–1.01). Muscular fitness appears to play some protective role against the risk of elevated blood pressure; particularly for the more prevalent measure: elevated DBP (44%). Effects may be restricted to Overweight and Unfit youth it is these the increased risk of elevated BP is and are less likely to engage in traditional cardiorespiratory fitness training. Research to determine the effects of muscular fitness training on blood pressure is warranted in these subgroups.

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Preventive Medicine

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Effect of variation of the central-hole depth and the axial anisotropy on the AB oscillations in a wide nanoring

The effect of the external magnetic field on the spectral properties of one-electron non-uniform quantum ring with radially directed hills is analysed. The corresponding one-particle wave equation is separable in the adiabatic limit, when the layer thickness is essentially smaller than its lateral dimension. Our calculations show that the presence of a single axially directed hill as well as a rise of the central hole thickness produce a quenching of the Aharonov-Bohm (AB) oscillations of the lower energy levels and of the magnetic momentum. However, as the number of radially directed hills is increased, the system exhibits again oscillations, resulted from an enhancement of tunnelling circular currents.

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Journal of Physics: Conference Series

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Antiviral effect of compounds derived from the seeds of Mammea americana and Tabernaemontana cymosa on Dengue and Chikungunya virus infections

Background: The transmission of Dengue virus (DENV) and Chikungunya virus (CHIKV) has increased worldwide, due in part to the lack of a specific antiviral treatment. For this reason, the search for compounds with antiviral potential, either as licensed drugs or in natural products, is a research priority. The objective of this study was to identify some of the compounds that are present in Mammea americana (M. americana) and Tabernaemontana cymosa (T. cymosa) plants and, subsequently, to evaluate their cytotoxicity in VERO cells and their potential antiviral effects on DENV and CHIKV infections in those same cells. Methods: Dry ethanolic extracts of M. americana and T. cymosa seeds were subjected to open column chromatographic fractionation, leading to the identification of four compounds: two coumarins, derived from M. americana; and lupeol acetate and voacangine derived from T. cymosa.. The cytotoxicity of each compound was subsequently assessed by the MTT method (at concentrations from 400 to 6.25 μg/mL). Pre- and post-treatment antiviral assays were performed at non-toxic concentrations; the resulting DENV inhibition was evaluated by Real-Time PCR, and the CHIKV inhibition was tested by the plating method. The results were analyzed by means of statistical analysis. Results: The compounds showed low toxicity at concentrations ≤ 200 μg/mL. The compounds coumarin A and coumarin B, which are derived from the M. americana plant, significantly inhibited infection with both viruses during the implementation of the two experimental strategies employed here (post-treatment with inhibition percentages greater than 50%, p < 0.01; and pre-treatment with percentages of inhibition greater than 40%, p < 0.01). However, the lupeol acetate and voacangine compounds, which were derived from the T. cymosa plant, only significantly inhibited the DENV infection during the post-treatment strategy (at inhibition percentages greater than 70%, p < 0.01). Conclusion: In vitro, the coumarins are capable of inhibiting infection by DENV and CHIKV (with inhibition percentages above 50% in different experimental strategies), which could indicate that these two compounds are potential antivirals for treating Dengue and Chikungunya fever. Additionally, lupeol acetate and voacangine efficiently inhibit infection with DENV, also turning them into promising antivirals for Dengue fever.

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BMC Complementary and Alternative Medicine

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Dengue in Latin America: Systematic Review of Molecular Epidemiological Trends

Dengue, the predominant arthropod-borne viral disease affecting humans, is caused by one of four distinct serotypes (DENV-1, -2, -3 or -4). A literature analysis and review was undertaken to describe the molecular epidemiological trends in dengue disease and the knowledge generated in specific molecular topics in Latin America, including the Caribbean islands, from 2000 to 2013 in the context of regional trends in order to identify gaps in molecular epidemiological knowledge and future research needs. Searches of literature published between 1 January 2000 and 30 November 2013 were conducted using specific search strategies for each electronic database that was reviewed. A total of 396 relevant citations were identified, 57 of which fulfilled the inclusion criteria. All four dengue virus serotypes were present and co-circulated in many countries over the review period (with the predominance of individual serotypes varying by country and year). The number of countries in which more than one serotype circulated steadily increased during the period under review. Molecular epidemiology data were found for Argentina, Bolivia, Brazil, the Caribbean region, Colombia, Ecuador, Mexico and Central America, Paraguay, Peru and Venezuela. Distinct lineages with different dynamics were found in each country, with co-existence, extinction and replacement of lineages occurring over the review period. Despite some gaps in the literature limiting the possibility for comparison, our review has described the molecular epidemiological trends of dengue infection. However, several gaps in molecular epidemiological information across Latin America and the Caribbean were identified that provide avenues for future research; in particular, sequence determination of the dengue virus genome is important for more precise phylogenetic classification and correlation with clinical outcome and disease severity.

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PLoS Neglected Tropical Diseases

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Cardiopulmonary and hematologic response to the test Course Navette 20 meters in University Students

Introduction: Young people who start the university life face a key stage for the acquisition of habits and lifestyles. The test Course Navette is one of the most used worldwide because of its easy measurement, validity, effectiveness and sensitivity in different age ranks. Material and methods: An observational, descriptive and transversal study with quantitative approach; with 100 students participating (43 men and 57 women) with an average age of 21.06 ± 2.43 at the University of Santander, Cúcuta. For the development of this research, were obtained measurements anthropometric, hematological, physiological and performance on an empty stomach Leger test. Results: 62% of participants had a BMI of normal weight, 24% overweight and obesity and underweight was 8 and 6% respectively. In turn 32% of men and 17.5% of women have high cardiovascular risk according to abdominal circumference. VO2max. in the Leger test was 32.92 ± 7.12 to 533.80 ± 371.34 meters traveled. Regarding glycemia before the test was 80.99 ± 11.91 and after 105.59 ± 20.89. Conclusion: No significant differences in fat percentage were found (p = 0,863), muscle (p = 0,740) and water (p = 0,804) after Leger test. However, there were significant changes in FC, TAS, TAD, red cells, white cells, hemoglobin, platelets and blood glucose levels (p = 0,000). Regarding the VO2max. (p = 0,597) and travel meters (p = 0,619) no differences were found by gender.

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Revista Mexicana de Cardiologia

Título del artículo:

Onset of the asphaltene flocculation and asphaltene hydrodynamic radius determination using H-diffusion-ordered spectroscopy DOSY NMR

During EOR recovery processes, asphaltenes macromolecules can flocculate and cause drastic changes in the petrophysical properties of the reservoir, therefore it is very important to determine the time at the flocculation begins and further the size of the aggregates, since ultimately this depends on whether these can be trapped in the porous media. This work aims to evaluate the change in the asphaltene hydrodynamic radius of at different concentrations of n-heptane and to detect the onset asphaltene floculation using a new technique known as 1H Diffusion ordered spectroscopy-NMR (DOSY-NMR). H-DOSY NMR is a method based on the pulsed field gradient spin-echo from nuclear magnetic resonance (PFGSE NMR) and it allows the identification of the molecular components of a mixture sample and at the same time obtain information of their size through the diffusion coefficient. For our specific case, the asphaltene hydrodynamic radius was 16.8 Å and the onset of asphaltene floculation can be observed when the concentration of solvent nheptane was 30 wt %.

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SPE Latin American and Caribbean Petroleum Engineering Conference Proceedings

Título del artículo:

A new multiplex PCR for species-specific diagnosis of human candidiasis

Introduction: Candidiases is a group of opportunistic infections caused by yeasts belonging to the genus Candida. Candida albicans is the most prevalent species in both superficial and deep infections, however, the clinical importance of non-albicans Candida has increased during the last decade, driving an urgent need for diagnostic tests that allow for species-level resolution and selection of the optimum therapeutic approach. Objective: To design and to optimize a new multiplex PCR assay for the simultaneous identification of the five most relevant species of Candida involved in human candidiasis etiology. Materials and methods: For primers design, the physical and thermodynamic restrictions that affect multiplex PCR performance were analyzed using Gene Runner and Mult-PSOS. As templates, the internal transcribed region 2 (ITR2) was selected for C. albicans (AJ249486.1), and topoisomerase II (TOPII) for C. parasilopsis (AB049144.1), C. krusei (AB049139.1), C. tropicalis (AB049141.1), and C. guillermondii (AB049145.1). We used ATCC strains of all these five species and clinical isolates as templates. Results: We designed ten oligonucleotides for the simultaneous amplification of the Candida species. The electrophoresis band profile was: C. albicans (206 bp), C. guillermondii (244 bp), C. tropicalis (474 bp), C. parasilopsis (558 bp), and C. krusei (419 bp). Conclusion: The new multiplex PCR assay designed in this study allowed a simultaneous and efficient amplification of the amplicons corresponding to the five species of Candida under study, with an adequate resolution in standard agarose gel.

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Biomedica