Central University of Venezuela
Recent publications
We herein disclose a new synthetic strategy for a diverse series of biologically interesting flavone‐coumarin molecular hybrids based on iron(III) triflate‐assisted direct and straightforward skeletal rearrangement of warfarin framework upon heating warfarin analogs in N, N‐dimethylformamide (DMF). Good yields, reasonable reaction time, broad substrate scope and tolerance of various functional groups, scalability, and operational simplicity are the key features of this newly developed method.
The Canary Islands are oceanic islands that encompass a wide diversity of geological ages, sizes, ecological regions, and orographic contexts that determine different isolation frameworks and provide a suitable geographical setting to address questions regarding genetic variation patterns and colonization processes. In the present study, we used nuclear microsatellites to quantitatively determine gene flow, colonization patterns, and geographical barriers in the Canarian endemic genus Parolinia, taking into account the dynamic geological ontogeny of the islands. Our genetic analyses showed a high number of shared alleles (68%) and low interspecific genetic differentiation, suggesting both a close relationship among the species of Parolinia and a likely recent origin of this Canarian endemic genus. MIGRATE analysis suggested a westward stepping stone colonization pattern from Gran Canaria to Tenerife, and then to La Palma and La Gomera. Supporting this hypothesis, P. schizogynoides (La Gomera Island) and P. aridanae (La Palma Island) clustered together in the STRUCTURE and PCoA analyses, and showed a high number of shared alleles and low genetic differentiation, which also suggests a recent migration from an ancestor from Tenerife Island. In addition, these analyses also point to P. ornata (Gran Canaria Island) as the genetically closest taxon to the putative ancestor of the genus. In view of the existence of genetic relationships within Parolinia, any population reinforcement programs should be carried out using genetic material with strict geographic and, when possible, genetic traceability to prevent anthropogenic hybridization. Translocations of individuals between different distribution areas should be avoided, and the most endangered species should be adequately represented in seed banks.
The Global initiative for chronic Obstructive Lung Disease (GOLD) report states that the diagnosis of chronic obstructive pulmonary disease (COPD) should be considered in individuals with chronic respiratory symptoms and / or exposure to risk factors. Forced spirometry demonstrating airflow obstruction after bronchodilation is required to confirm the diagnosis using a threshold of forced expiratory volume in 1 s (FEV 1 ) / forced vital capacity (FVC) ratio<0.7. This GOLD Science Committee review weighs the evidence for using pre- or post-bronchodilator (BD) spirometry to diagnose COPD. Cohort studies have shown that pre- and post-BD spirometry give concordant diagnostic results in most cases, although the prevalence of COPD is up to 36% lower with post-BD values. Discordant results may occur in “volume” or “flow” responders. Volume responders have reduced FVC due to gas trapping causing FEV 1 / FVC ratio >0.7 pre-BD, but a volume response occurs post-BD with a greater improvement in FVC relative to FEV 1 decreasing the ratio to <0.7. Flow responders show a greater FEV 1 improvement relative to FVC which may increase FEV 1 / FVC from <0.7 pre-BD to >0.7 post-BD; these individuals have an increased likelihood of developing post-BD obstruction during follow up and require monitoring longitudinally. GOLD 2025 recommends using pre-BD spirometry to rule out COPD and post-BD measurements to confirm the diagnosis. This will reduce clinical workload. Post-BD results close to the threshold should be repeated to ensure a correct diagnosis is made. Post-BD measurements ensure that volume responders are not overlooked and limit COPD overdiagnosis.
Accurate flood mapping is essential for assessing flood hazards, particularly in areas like the lower Baro flood plain in Ethiopia where floods pose significant challenges to society. This study aims to enhance flood inundation mapping by integrating the Hydrologic Engineering Centre-Hydrologic Modeling System (HEC-HMS) and Artificial Neural Network (ANN) with the Hydrologic Engineering Centre-River Analysis System (HEC-RAS). Data from 14 meteorological stations and 3 streamflow stations, spanning from 2000 to 2016, including soil characteristics, Digital Elevation Model, and land use data, were used in the analysis. The combination of ANN and HEC-HMS models provided runoff values for input into the HEC-RAS model, resulting in the creation of accurate flood inundation maps. The HEC-HMS-ANN model was evaluated using statistical metrics such as Nash Sutcliffe (NSE), Root Mean Square Error (RMSE), and Correlation coefficient (R²) demonstrating excellent performance with NSE of 0.9924, RMSE of 24 m³/s, and R² of 0.9926. Calibration and validation of flood inundation outputs from HEC-RAS using the Normalized Difference Water Index (NDWI) revealed high accuracy with overlapping percentages of 90.6% and 91% during the calibration and validation phases, respectively. This integration of models significantly enhances prediction accuracy compared to traditional flood forecasting methods in the Gambella gaging station and Itang area.
The structural modification of hole‐transporting materials (HTMs) is an effective strategy for enhancing photovoltaic performance in perovskite solar cells (PSCs). Herein, a series of dithienopyran (DTP)‐based HTMs (Me‐H, Ph‐H, CF3‐H, CF3‐mF, and CF3‐oF) is designed and synthesized by substituting different functional groups on the DTP unit and are used fabricating PSCs. In comparison with Me‐H having two methyl substituents on the dithienopyrano ring, the Ph‐H having two phenyl substituents on the ring exhibits higher PCEs. Notably, the incorporation of trifluoromethyl groups in CF3‐H endows the molecule with a larger dipole moment, deeper HOMO energy level, better film morphology, closer molecular stacking, more efficient defect‐passivation, enhanced hydrophobicity, and better photovoltaic performance when compared with the Ph‐H counterpart. Furthermore, the HTMs of CF3‐mF and CF3‐oF, which feature fluorine‐substituted triphenylamine, demonstrated excellent film‐forming properties, more suitable energy levels, enhanced charge mobility, and improved passivation of the buried interface between HTMs and perovskite. As a result, PSCs employing CF3‐mF and CF3‐oF gave impressive PCEs of 23.41 and 24.13%, respectively. In addition, the large‐area (1.00 cm²) PSCs based on CF3‐oF achieved a PCE of 22.31%. Moreover, the PSCs devices with CF3 series HTMs exhibited excellent long‐term stability under different conditions.
Leaf and wood functional traits of trees are related to growth, reproduction, and survival, but the degree of phylogenetic conservatism in these relationships is largely unknown. In this study, we describe the variability of strategies involving leaf, wood and demographic characteristics for tree genera distributed across the Amazon Region, and quantify phylogenetic signal for the characteristics and their relationships. Leaf and wood traits are aligned with demographic variables along two main axes of variation. The first axis represents the coordination of leaf traits describing resource uptake and use, wood density, seed mass, and survival. The second axis represents the coordination between size and growth. Both axes show strong phylogenetic signal, suggesting a constrained evolution influenced by ancestral values, yet the second axis also has an additional, substantial portion of its variation that is driven by functional correlations unrelated to phylogeny, suggesting simultaneously higher evolutionary lability and coordination. Synthesis. Our results suggest that life history strategies of tropical trees are generally phylogenetically conserved, but that tree lineages may have some capability of responding to environmental changes by modulating their growth and size. Overall, we provide the largest‐scale synopsis of functional characteristics of Amazonian trees, showing substantial nuance in the evolutionary patterns of individual characteristics and their relationships. Read the free Plain Language Summary for this article on the Journal blog.
As augmented reality (AR) glasses technology evolves, volume holographic diffractive waveguide designs are increasingly adopted to enhance portability and performance. Traditionally, these systems require separate geometric and wave optics approaches to handle ray propagation and holographic element diffraction, adding significant complexity to the design process. This study presents an innovative pure ray tracing simulation method that integrates geometric and wave optics seamlessly. By incorporating Kogelnik's coupled wave theory, our model accurately predicts the diffraction behavior of volume holographic optical elements (VHOEs) and converts this information into ray data for tracing, enabling exact AR imaging simulations. Applied to the design of volume holographic waveguide AR glasses, human vision simulations, and experiments validated this method's reliability, demonstrating its versatility and effectiveness. This model improves design efficiency and promotes innovative advancements in cross-theoretical optical system design, positioning it as a crucial tool for future AR glasses development.
Objectives: Leveraging the non-monolithic structure of Latin America, which represents a large variability in social determinants of health (SDoH) and high levels of genetic admixture, we aim to evaluate the relative contributions of SDoH and genetic ancestry in predicting dementia risk in Latin American populations Methods: Community-dwelling participants aged 65 and older (N = 3808) from Cuba, Dominican Republic, Mexico, and Peru completed the 10/66 protocol assessments. Dementia was diagnosed using the cross-culturally validated 10/66 algorithm. The primary outcome measured was the risk of developing dementia. Multivariate linear regression models adjusted for SDoH were used in the main analysis. Results: We observed extensive three-way (African/European/Native American) genetic ancestry variation between countries. Individuals with higher proportions of Native American (>70%) and African American (>70%) ancestry were more likely to exhibit factors contributing to worse SDoH, such as lower educational levels (p <0.001), lower SES (p < 0.001), and higher frequency of vascular risk factors (p < 0.001). In unadjusted analysis, American individuals with predominant African ancestry exhibited a higher dementia frequency (p = 0.03) and both Native and African ancestry predominant groups showed lower cognitive performance relative to those with higher European ancestry (p < 0.001). However, after adjusting for measures of SDoH, there was no association between ancestry proportion and dementia probability, and ancestry proportions no longer significantly accounted for the variance in cognitive performance (African predominant p = 0.31 [–0.19, 0.59] and Native predominant p = 0.74 [–0.24, 0.33]). Conclusions: The findings suggest that social and environmental factors play a more crucial role than genetic ancestry in predicting dementia risk in Latin American populations. This underscores the need for public health strategies and policies that address these social determinants to reduce dementia risk in these communities effectively.
Objectives: Because of the continued transition to older populations, various strategies have been developed to estimate the social impact and burden of health care. Regarding mental health, a strategy in the elderly is the measurement of neuropsychiatric symptoms (NPS), these include a wide range of behavioral and psychological manifestations. These are more frequent in the presence of some diseases, such as neurodegenerative syndromes, among which dementias and Parkinson’s disease (PD) stand out. The present study seeks to analyze the frequency of NPS, its relationship with the presence or absence of neurodegenerative syndromes and some characteristics of the elderly and caregivers. Methods: This is an analysis of data from 12,865 elderly people evaluated within the protocols of the Dementia Research Group 10/66 in 6 Latin American countries (Cuba, Dominican Republic, Puerto Rico, Mexico, Venezuela and Peru). The presence or absence of parkinsonism, dementia and parkinsonism plus dementia (PDD) was identified through previously validated and published Methods. The NPS were assessed using the 12-symptom questionnaire version of the Neuropsychiatric Inventory. Other characteristics such as age, sex and education, in patients and caregivers; socioeconomic status, disability and comorbidities in the elderly; relationship with the elderly, needs and care-burden were assessed in careers. Results: The most frequent symptoms were depression and sleep disorders in the four groups (without non-NDS neurodegenerative syndromes, parkinsonism, dementia and PDD, ranging from 23% to 49%. About a third of the elderly with parkinsonism, half of those with dementia, and 3 out of 5 of the elderly with PDD had 3 or more NPS. The odds ratios (OR) of each NPS measure by multivariate logistic regression models shown OR from 1.4 to 1.9 in the presence of parkinsonism; between 1.7 and 9.3 in the presence of dementia; and between 1.9 and 10.2 in the presence of PDD. Conclusions: From a clinical and public mental health perspective, it is necessary to implement systematic Methods for NPS screening, as well as develop support strategies for families and caregivers, mainly of those with neurodegenerative syndromes.
Objectives: Studies in PD have traditionally focused on motor features, however, interest in non-motor manifestations has increased resulting in improved knowledge regarding the prognosis of the disease. Although several studies have explored the incidence of dementia in PD cohorts, these studies have been conducted mainly in reference centers in high-income countries (HIC). In this study we aimed to analyze the prevalence of cognitive impairment in people with parkinsonism and PD and its association with incident dementia in a population- based study, of elderly from six Latin American countries. Methods: This report consists of the analysis of data from a follow-up of 12,865 elderly people aged 65 years or older, carried out by 10/66 Dementia Research Group. Residents of urban and rural areas, from six low and middle- income countries (Cuba, Dominican Republic, Puerto Rico, Venezuela, Mexico and Peru). Exposures include parkinsonism and PD defined according to the UK Parkinson’s Disease Society Brain Bank diagnostic criteria. Cognitive impairment was the main exposure and dementia was measured through the dementia diagnosis algorithm from 10/66 DRG. Results: At baseline, the overall prevalence of cognitive impairment was 14% (n = 1,581), in people with parkinsonism and PD, it was of 30.0% and 26.2%, respectively. Parkinsonism and PD were individually associated with prevalent and incident dementia after controlling for age, sex, and education. The pooled odds ratios from a fixed-effects meta-analysis were 2.2 (95% CI: 1.9 – 2.6) for parkinsonism and 1.9 (95% CI: 1.4 – 2.4) for PD. Regarding incident dementia, the pooled sub-Hazard ratio estimated using a competing risk model was 1.5 (95% CI: 1.2 –1.9) for parkinsonism and 1.5 (95% CI: 1.0 – 2.2) forPD. Conclusions: Parkinsonism and PD were associated cross-sectionally with the presence of cognitive impairment, and prospectively with incident dementia in elderly people in the community population of Latin America studied. Systematic screening for cognitive impairment and dementia with valid tools in PD patients may help with earlier detection of those at highest risk for adverse outcomes. Identifying modifiable risk factors could potentially lead to efficient interventions even in advanced stages of PD.
Background: Limited knowledge exists about the association between Parkinsonism or Parkinson’s disease (PD) and cognitive impairment and dementia in Latin America. Objectives: The study aimed to determine the cross-sectional and prospective associations between Parkinsonism and PD with cognitive impairment and dementia in a large multi-country cohort in Latin America. Methods: The 10/66 is a prospective, observational cohort study. This population-based cohort study was based in six Latin American countries: Cuba, Dominican Republic, Puerto Rico, Venezuela, Mexico, and Peru. The study includes 12,865 participants from six countries, including residents aged 65 years and living in urban and rural catchment areas. Exposures included diagnosed Parkinsonism and PD defined according to the United Kingdom Parkinson’s Disease Society Brain Bank diagnostic criteria. Cognitive impairment was the main outcome measure for cross-sectional analysis and dementia was used to measure the prospective association with the exposures. Logistic regression models were used to explore the association between Parkinsonism/PD with cognitive impairment at baseline. Competing risk models were used to assess the prospective association between Parkinsonism/PD with incident dementia accounting for competing risk of mortality. Individual country analyses were combined via fixed-effect meta-analysis. Results: At baseline, the prevalence of cognitive impairment in people with Parkinsonism and PD was 30% and 26.2%, respectively. Parkinsonism (OR 2.2 (95%CI 1.9 – 2.6)) and PD (1.9 (95%CI 1.4 – 2.4)) were individually associated with baseline and incident cognitive impairment after accounting for age, sex, and education, after pooling. In competing risk models, the pooled sub- hazard ratios for dementia in the fixed effect metanalysis were 1.5 (95%CI 1.2 – 1.9) for parkinsonism and 1.5 (95%CI 1.0 – 2.2) for PD. Conclusions: Parkinsonism and PD were cross-sectionally associated with cognitive impairment and prospectively associated with incident dementia in Latin America. Routine screening for cognitive impairment and dementia with validated tools in PD patients may aid earlier detection of those at greater risk ofadverseoutcomes.
Bovine brucellosis (BB) is a cosmopolitan zoonotic disease caused by certain bacteria of the genus Brucella. It has negative health implications for the cattle, economic implications for the owners and is present in numerous cattle and wildlife populations worldwide. To determine the seroprevalence of BB in dual-purpose herds and assess its impact in the southern part of the Department of Atlántico, northern Colombia. 1,000 female cattle were tested for brucellosis, using the Rose Bengal Plate Test (RBPT) and indirect ELISA (iELISA) as screening and confirmatory tests, respectively. Of these, 100 animals tested positive by RBPT and 204 were inconclusive, while 38 positive animals were identified by iELISA. Consequently, the apparent seroprevalence was 3.8%, and the estimated true prevalence was 4.4%. Based on estimates of the economic losses caused by BB, the cost was calculated at 2,496,364COP(2,496,364 COP (822 USD) per animal. The costs identified in this study include medication costs, loss of lactation, and others. It highlights the significant impact of BB on food security, particularly concerning the availability of and access to bovine food products, as well as on the economy of livestock farmers in the region.
In this study, intrinsic ZnO powder was sintered and intercalated with particles. The resulting powder, along with a commercial p-type product, was consolidated into bulk materials, and their thermal conductivity was measured across a temperature range of 350 K–700 K. The thermal conductivity of the commercial p-type ZnO was found to be lower than that of intrinsic ZnO, attributed to controlled doping. Notably, our demonstration illustrated that the thermal conductivity can be reduced by a factor of 5–10 in the presence of AlZn2O4 and ZnP2 precipitates. This methodology presents a feasible approach for the future design of ZnO-based thermoelectric materials, particularly for thermal heat scavenging applications.
Unlike traditional multi‐step synthetic approaches, we developed a single‐step synthesis of versatile π‐conjugated building blocks bearing post‐functionalizable C−H and C−Br bonds. Direct C−H arylation of 3‐bromothiophene with various iodo(hetero)aryls was successfully carried out with good regio‐ and chemo‐selectivity. Under optimized reaction conditions, 20 new compounds were facilely prepared in yields up to 91 %. One of the obtained compounds was demonstrated to further extend its conjugation length using a succinct synthetic plan to create two symmetrical oligo(hetero)aryls (MLC01 and MLC02) that were fabricated as effective hole‐transporting materials (HTM) for perovskite solar cells (PSC). PSC devices utilizing MLC01 as hole‐transport layer displayed promising power conversion efficiencies of up to 17.01 %.
Platelet activating factor (PAF) has been implicated in the pathophysiology of acute lung injury. The aim of this work is to study the effect of PAF on isolated and perfused rabbit lungs with blood and with a blood-free solution. 24 isolated and perfused rabbit lungs have been used: 8 control preparations (CP), 4 vehicles preparations (VP), 8 PAF preparations (PP) to which we administered PAF (1 µg/Kg of rabbit weight) and 4 acellular preparations (AP) with the same dose of PAF as in PP but dissolved in BSA-Krebs buffer solution. In the preparations pulmonary artery pressure (Ppa), airway pressure (Paw), left atria pressure (Pla) and fluid filtration rate (FFR) were registered. Ppa resulted in a significant difference in AP vs PP, with a value of 21 cm of water (CI 95 %: 12–26) vs 205.1 cm of water (CI 95 %: 141.3 - 271) respectively. A increase in FFR was observed in PP but it did not occur in AP, the difference being statistically significant: 5.515 g/min (CI 95 %: 2.425 - 8.865) vs 0.049 g/min (CI 95 %: 0.008 - 0.32) respectively. Paw was statistically different in PP vs AP, with a value of 14.3 cm of water (CI 95 %: 11.57 - 16.7) vs 8.5 cm of water (CI 95 %: 8–9) respectively. These results suggest that PAF does not have a direct effect on the endothelium or smooth muscle in the production of lung edema.
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Miguel Angel Briceno Gil
  • Instituto de Filosofía
Alejandro Salvador
  • Departamento de Produccion and Industria Animal
Thais del-Valle Diaz
  • Instituto de Reproducción Animal
Maria L Serrano
  • Faculty of Pharmacy
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Caracas, Venezuela
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Dra Cecilia García