Photochemical Upconversion.

Photochemical upconversion is a process whereby two lower-energy photons are converted into a higher-energy photon by sensitized triplet-triplet annihilation. While recent interest in this process has been motivated by improving the efficiencies of solar cells, many applications are being explored. In this review, we address the underlying physicochemical phenomena that are responsible for photochemical upconversion. We review their kinetics, and the requirements for annihilators and sensitizers to design efficient upconversion systems. We discuss the spin physics of the bi-excitonic interactions and how the spin character of the triplet pairs can fundamentally limit the upconversion efficiency and give rise to the magnetic field effect on delayed photoluminescence. Finally, we address light-matter coupling phenomena that could be employed to enhance photochemical upconversion.

Flexible cloglog links for binomial regression models as an alternative for imbalanced medical data.

The complementary log-log link was originally introduced in 1922 to R. A. Fisher, long before the logit and probit links. While the last two links are symmetric, the complementary log-log link is an asymmetrical link without a parameter associated with it. Several asymmetrical links with an extra parameter were proposed in the literature over last few years to deal with imbalanced data in binomial regression (when one of the classes is much smaller than the other); however, these do not necessarily have the cloglog link as a special case, with the exception of the link based on the generalized extreme value distribution. In this paper, we introduce flexible cloglog links for modeling binomial regression models that include an extra parameter associated with the link that explains some unbalancing for binomial outcomes. For all cases, the cloglog is a special case or the reciprocal version loglog link is obtained. A Bayesian Markov chain Monte Carlo inference approach is developed. Simulations study to evaluate the performance of the proposed algorithm is conducted and prior sensitivity analysis for the extra parameter shows that a uniform prior is the most convenient for all models. Additionally, two applications in medical data (age at menarche and pulmonary infection) illustrate the advantages of the proposed models.

Wavelength-Gated Photochemical Synthesis of Phenalene Diimides.

Herein, we pioneer a wavelength-gated synthesis route to phenalene diimides. Consecutive Diels-Alder reactions of methylisophthalaldehydes and maleimides afford hexahydro-phenalene-1,6-diol diimides via 5-formyl-hexahydro-benzo[f]isoindoles as the intermediate. Both photoreactions are efficient (82-99 % yield) and exhibit excellent diastereoselectivity (62-98 % d.r.). The wavelength-gated nature of the stepwise reaction enables the modular construction of phenalene diimide scaffolds by choice of substrate and wavelength. Importantly, this synthetic methodology opens a facile avenue to a new class of persistent phenalenyl diimide neutral radicals, constituting a versatile route to spin-active molecules.

Combining Photodeprotection and Ligation into a Dual-Color Gated Reaction System.

We report a photochemical reaction system which requires activation by two colors of light. Specifically, a dual wavelength gated system is established by fusing the visible light mediated deprotection of a dithioacetal with the UV light activated Diels-Alder reaction of an o-methylbenzaldehyde with N-ethylmaleimide. Critically, both light sources are required to achieve the Diels-Alder adduct, irradiation with visible or UV light alone does not lead to the target product. The introduced dual gated photochemical system is particularly interesting for application in light driven 3D printing, where two color wavelength activated photoresists may become reality.

It's a Trap: Thiol-Michael Chemistry on a DASA Photoswitch.

Donor-acceptor Stenhouse adducts (DASA) are popular photoswitches capable of toggling between two isomers depending on the light and temperature of the system. The cyclized polar form is accessed by visible-light irradiation, whereas the linear nonpolar form is recovered in the dark. Upon the formation of the cyclized form, the DASA contains a double bond featuring a ß-carbon prone to nucleophilic attack. Here, an isomer selective thiol-Michael reaction between the cyclized DASA and a base-activated thiol is introduced. The thiol-Michael addition was carried out with an alkyl (1-butanethiol) and an aromatic thiol (p-bromothiophenol) as reaction partners, both in the presence of a base. Under optimized conditions, the reaction proceeds preferentially in the presence of light and base. The current study demonstrates that DASAs can be selectively trapped in their cyclized state.

Characterization, processing potential and drivers for preference of pepper cultivars in the production of sweet or spicy jellies.

Due to the importance of studying alternatives to reduce pepper post-harvest loss and verify the processing potential of the several cultivars/varieties available, the objective of this study was to characterize common peppers in Brazil, and to evaluate their potential for further processing into jelly form. More specifically, the most-consumed species and varieties in Brazil were investigated, that is: Habanero, Cheiro do Norte, Biquinho, Malagueta, Cayenne, Paprika and Dedo de Moça. Additionally, the drivers of liking for pepper jelly were sought so as to understand the desirable characteristics of this product. The different peppers were initially assessed by the following physical and physicochemical analyses: length, diameter, unit mass, total soluble solids, total titratable acidity, pH, color, total phenolic content, antioxidant activity, and vitamin C levels. Jellies made with different pepper types were also analyzed for total titratable acidity, pH, color, and texture profile, and a sensory study was conducted to elucidate the drivers of liking. As expected, different pepper types varied in physical and physicochemical properties, and the resulting jellies also differed in terms of physical, physicochemical, textural and sensory characteristics. In general, less pungent peppers (Biquinho, Paprika and Cheiro do Norte) were the most suitable for processing to produce jellies with more desirable attributes for consumers: reddish color, characteristic flavor and aroma of a pepper, sweet taste, and low pungency.

Photoprotection enhanced by red cell wall pigments in three East Antarctic mosses.

BACKGROUND: Antarctic bryophytes (mosses and liverworts) are resilient to physiologically extreme environmental conditions including elevated levels of ultraviolet (UV) radiation due to depletion of stratospheric ozone. Many Antarctic bryophytes synthesise UV-B-absorbing compounds (UVAC) that are localised in their cells and cell walls, a location that is rarely investigated for UVAC in plants. This study compares the concentrations and localisation of intracellular and cell wall UVAC in Antarctic Ceratodon purpureus, Bryum pseudotriquetrum and Schistidium antarctici from the Windmill Islands, East Antarctica. RESULTS: Multiple stresses, including desiccation and naturally high UV and visible light, seemed to enhance the incorporation of total UVAC including red pigments in the cell walls of all three Antarctic species analysed. The red growth form of C. purpureus had significantly higher levels of cell wall bound and lower intracellular UVAC concentrations than its nearby green form. Microscopic and spectroscopic analyses showed that the red colouration in this species was associated with the cell wall and that these red cell walls contained less pectin and phenolic esters than the green form. All three moss species showed a natural increase in cell wall UVAC content during the growing season and a decline in these compounds in new tissue grown under less stressful conditions in the laboratory. CONCLUSIONS: UVAC and red pigments are tightly bound to the cell wall and likely have a long-term protective role in Antarctic bryophytes. Although the identity of these red pigments remains unknown, our study demonstrates the importance of investigating cell wall UVAC in plants and contributes to our current understanding of UV-protective strategies employed by particular Antarctic bryophytes. Studies such as these provide clues to how these plants survive in such extreme habitats and are helpful in predicting future survival of the species studied.

Urinary Incontinence in Physically Active Young Women: Prevalence and Related Factors.

This cross-sectional survey aims to (1) verify the prevalence of urinary incontinence and its impact on the quality of life among nulliparous fit women, and to (2) analyze whether urinary incontinence is influenced by the intensity of the sport (high- vs. low-impact) or by the volume of physical activity (minutes per week) performed. Two hundred forty-five nulliparous women (18-40 years) completed the International Consultation on Incontinence Questionnaire-Short Form, the Kings Health Questionnaire and a questionnaire regarding demographic and training variables. Overall 22.9% of the participants self-reported urinary incontinence, and among them, 60.7% had stress urinary incontinence. Incontinent women demonstrated worse quality of life than continent females (p=0.000). Women practicing high-impact sports presented higher frequency in loss of urine than those practicing low-impact sports (p=0.004). Regardless the intensity of the sport, the volume of exercise showed positive association with the frequency of loss of urine (p=0.005, r=0.475). In conclusion, almost one fourth of the women enrolled in this study reported symptoms of urinary incontinence and worse quality of life than those who were continent. Women who practice high-impact sports or who have higher volume of training should be aware of the symptoms associated with pelvic floor dysfunction, since they seem to predispose to urine leakage.

Spectroscopic Studies on the Interaction of Metallic Ions with an Imidazolyl-Phenolic System.

A fluorescent imidazolyl-phenolic compound was applied on the detection of metallic species (Cu(2+), Al(3+), Cr(3+) and Fe(3+)) in a CH3CN/H2O (95/5, v/v) media. The presence and concentration of these cations altered significantly the emission profile of the probe, mainly lowering the signal intensity at 466 nm, while a new emission band around 395 nm appeared (for the trivalent ions). These results were rationalized as a combination of collisional quenching (KSV in the 10(3)-10(4) L mol(-1) range) and formation of a coordinated compound. The later disrupts the Excited State Intramolecular Proton Transfer that regulates the keto-enol tautomerism originally present on the free probe. Since the quenching efficiency and the obtained emission profiles are drastically different for Cu(2+) and Fe(3+) ions, this allows their differential recognition.

Moss δ(13) C: an accurate proxy for past water environments in polar regions.

Increased aridity is of global concern. Polar regions provide an opportunity to monitor changes in bioavailable water free of local anthropogenic influences. However, sophisticated proxy measures are needed. We explored the possibility of using stable carbon isotopes in segments of moss as a fine-scale proxy for past bioavailable water. Variation in δ(13) C with water availability was measured in three species across three peninsulas in the Windmill Islands, East Antarctica and verified using controlled chamber experiments. The δ(13) C from Antarctic mosses accurately recorded long-term variations in water availability in the field, regardless of location, but significant disparities in δ(13) C between species indicated some make more sensitive proxies. δ(13) CSUGAR derived from living tissues can change significantly within the span of an Antarctic season (5 weeks) in chambers, but under field conditions, slow growth means that this technique likely represents multiple seasons. δ(13) CCELLULOSE provides a precise and direct proxy for bioavailable water, allowing reconstructions for coastal Antarctica and potentially other cold regions over past centuries.

Phytoremediation of hydrocarbon contaminants in subantarctic soils: an effective management option.

Accidental fuel spills on world heritage subantarctic Macquarie Island have caused considerable contamination. Due to the island's high latitude position, its climate, and its fragile ecosystem, traditional methods of remediation are unsuitable for on-site clean up. We investigated the tolerance of a subantarctic native tussock grass, Poa foliosa (Hook. f.), to Special Antarctic Blend (SAB) diesel fuel and its potential to reduce SAB fuel contamination via phytoremediation. Toxicity of SAB fuel to P. foliosa was assessed in an 8 month laboratory growth trial under growth conditions which simulated the island's environment. Single seedlings were planted into 1 L pots of soil spiked with SAB fuel at concentrations of 1000, 5 000, 10,000, 2000 and 40,000 mg/kg (plus control). Plants were harvested at 0, 2, 4 and 8 months and a range of plant productivity endpoints were measured (biomass production, plant morphology and photosynthetic efficiency). Poa foliosa was highly tolerant across all SAB fuel concentrations tested with respect to biomass, although higher concentrations of 20,000 and 40,000 mg SAB/kg soil caused slight reductions in leaf length, width and area. To assess the phytoremediation potential of P. foliosa (to 10 000 mg/kg), soil from the planted pots was compared with that from paired unplanted pots at each SAB fuel concentration. The effect of the plant on SAB fuel concentrations and the associated microbial communities found within the soil (total heterotrophs and hydrocarbon degraders) were compared between planted and unplanted treatments at the 0, 2, 4 and 8 month harvest periods. The presence of plants resulted in significantly less SAB fuel in soils at 2 months and a return to background concentration by 8 months. Microbes did not appear to be the sole driving force behind the observed hydrocarbon loss. This study provides evidence that phytoremediation using P. foliosa is a valuable remediation option for use at Macquarie Island, and may be applicable to the management of fuel spills in other cold climate regions.

Host metabolomic responses in recurrent P. vivax malaria.

Malaria is the leading parasitic disease worldwide, with P. vivax being a major challenge for its control. Several studies have indicated metabolomics as a promising tool for combating the disease. The study evaluated plasma metabolomic profiles of patients with recurrent and non-recurrent P. vivax malaria in the Brazilian Amazon. Metabolites extracted from the plasma of P. vivax-infected patients were subjected to LC-MS analysis. Untargeted metabolomics was applied to investigate the metabolic profile of the plasma in the two groups. Overall, 51 recurrent and 59 non-recurrent patients were included in the study. Longitudinal metabolomic analysis revealed 52 and 37 significant metabolite features from the recurrent and non-recurrent participants, respectively. Recurrence was associated with disturbances in eicosanoid metabolism. Comparison between groups suggest alterations in vitamin B6 (pyridoxine) metabolism, tyrosine metabolism, 3-oxo-10-octadecatrienoate ß-oxidation, and alkaloid biosynthesis II. Integrative network analysis revealed enrichment of other metabolic pathways for the recurrent phenotype, including the butanoate metabolism, aspartate and asparagine metabolism, and N-glycan biosynthesis. The metabolites and metabolic pathways predicted in our study suggest potential biomarkers of recurrence and provide insights into targets for antimalarial development against P. vivax.

N-ethylmaleimide activates a Cl(-)-independent component of K(+) flux in mouse erythrocytes.

The K-Cl cotransporters (KCCs) of mouse erythrocytes exhibit higher basal activity than those of human erythrocytes, but are similarly activated by cell swelling, by hypertonic urea, and by staurosporine. However, the dramatic stimulation of human erythroid KCCs by N-ethylmaleimide (NEM) is obscured in mouse erythrocytes by a prominent NEM-stimulated K(+) efflux that lacks Cl(-)-dependence. The NEM-sensitivity of Cl(-)-independent K(+) efflux of mouse erythrocytes is lower than that of KCC. The genetically engineered absence of the K-Cl cotransporters KCC3 and KCC1 from mouse erythrocytes does not modify Cl(-)-independent K(+) efflux. Mouse erythrocytes genetically devoid of the Gardos channel KCNN4 show increased NEM-sensitivity of both Cl(-)-independent K(+) efflux and K-Cl cotransport. The increased NEM-sensitivity and stimulation magnitude of Cl(-)-independent K(+) efflux in mouse erythrocytes expressing transgenic hypersickling human hemoglobin SAD (HbSAD) are independent of the presence of KCC3 and KCC1, but absence of KCNN4 reduces the stimulatory effect of HbSAD. NEM-stimulated Cl(-)-independent K(+) efflux of mouse red cells is insensitive to ouabain and bumetanide, but partially inhibited by chloroquine, barium, and amiloride. The NEM-stimulated activity is modestly reduced at pH6.0 but not significantly altered at pH8.0, and is abolished at 0°C. Although the molecular identity of this little-studied K(+) efflux pathway of mouse erythrocytes remains unknown, its potential role in the pathophysiology of sickle red cell dehydration will be important for the extrapolation of studies in mouse models of sickle cell disease to our understanding of humans with sickle cell anemia.

Hospitalizations for ambulatory care-sensitive conditions in children, Rondônia, Brazil, 2008-2019. / Internações por condições sensíveis à atenção primária em crianças, Rondônia, Brasil, 2008-2019.

This study aimed to define the profile of hospitalizations of children in public hospitals of 52 municipalities of the state of Rondônia, Brazil. We performed an ecological time series study using secondary data provided by the Hospital Information System. The annual trend of Hospitalizations was presented by age group and health region. Linear regression was performed using the Prais-Winsten technique of the statistical package Stata, version 11.0. Hospitalizations for gastrointestinal diseases were found to be decreasing in all age groups, just as those for vaccine-preventable diseases in children aged between 1 and 9 years. Hospitalizations for skin and subcutaneous tissue diseases were increasing in all ages, as well as those caused by epilepsies in children aged 1 to 9 and those caused by diseases related to childbirth and puerperium. Health regions showed a varied hospitalization profile. A stable trend was found in the Cone Sul, Madeira-Mamoré, Café, Vale do Guaporé, and Vale do Jamari regions, whereas a declining trend was found in the Central and Zona da Mata regions. The high rates of hospitalizations for ambulatory care-sensitive conditions in children show how inefficient strategies and investments in primary care have been in the state of Acre, Brazil.

Objetivou-se caracterizar o perfil de internações de crianças na rede pública dos 52 municípios do estado de Rondônia, Brasil, no período de 2008 a 2019. Trata-se de um estudo de série temporal do tipo ecológico, com dados secundários do Sistema de Informações Hospitalares. A tendência anual das internações foi apresentada por faixa etária e regional de saúde. Foi realizada regressão linear aplicando a técnica de Prais-Winsten no pacote estatístico Stata, versão 11.0. As internações por doenças gastrointestinais tiveram declínio em todas as faixas etárias, assim como pelas doenças previníveis por imunizantes entre 1 a 9 anos. As internações por doenças de pele e tecido subcutâneo foram crescentes em todas as idades, as epilepsias em idades de 1 a 9 anos e pelas doenças relacionadas ao parto e puerpério foi crescente. As regiões de saúde apresentaram perfil de internações variável, com tendência estável nas regiões Cone Sul, Madeira-Mamoré, Café, Vale do Guaporé, Vale do Jamari; e em declínio nas regiões Central e Zona da Mata. As elevadas taxas de internações por condições sensíveis à atenção primária em crianças refletem a pouca efetividade das estratégias e dos investimentos na esfera da atenção primária no estado.

Cation-leak stomatocytosis in standard schnauzers does not cosegregate with coding mutations in the RhAG, SLC4A1, or GLUT1 genes associated with human disease.

Autosomal dominant overhydrated cation-leak stomatocytosis in humans has been associated with missense mutations in the erythroid membrane transport genes AE1, RhAG, and GLUT1. Syndromic stomatocytosis has been reported in three dog breeds, but stomatocytosis in Standard Schnauzers is usually asymptomatic, and is accompanied by minimal if any anemia. We have extended the evaluation of a cohort of schnauzers. We found that low-level stomatocytosis was accompanied by increased MCV and increased red cell Na content, and minimal or no reticulocytosis. Red cells from two affected dogs exhibited increased currents in on-cell patches measured in symmetrical NaCl solutions, but Na,K-ATPase and NKCC-mediated cation flux was minimal. Three novel coding polymorphisms found in canine RhAG cDNA and three novel polymorphisms found in canine SLC4A1 cDNA did not cosegregate with MCV or Na content. The GLUT1 cDNA sequence was normal. We conclude that unlike human overhydrated cation-leak stomatocytosis, stomatocytosis in this cohort of Standard Schnauzers is not caused by mutations in the genes encoding RhAG, SLC4A1, or GLUT1.

Prevalence and Factors Associated With Out-of-Pocket Pharmaceutical Expenditure Among Primary Healthcare Patients: Evidence From the Prover Project.

OBJECTIVES: This study aimed to determine the prevalence and associated factors of out-of-pocket pharmaceutical expenditure (OOPPE) among primary healthcare patients. METHODS: The study is part of the Prover Project, an exit survey conducted in 2017 in a large city (population 234 937) in Minas Gerais State, Brazil. A representative sample of patients (n = 1219) from pharmaceutical services based on primary healthcare was selected. Three components of OOPPE were assessed: the general prevalence, the types of medicines purchased (medicines for the treatment of chronic diseases, medicines for the treatment of acute diseases, or herbal medicines), and coverage by the National Health System. The factors associated with OOPPE were examined applying a modified Andersen's behavioral model of health services use. Data were analyzed using descriptive statistics and logistic regression. RESULTS: The overall prevalence of OOPPE was 77%. Most patients who had OOPPE purchased medicines to treat chronic diseases (94%). In addition, these patients purchased medicines covered by public insurance but were out of stock (85%). OOPPE was associated with enabling factors, such as higher personal income (odds ratio [OR] 1.92; 95% confidence interval [CI] 1.02-3.62), holding health insurance (OR 1.40; 95% CI 1.01-1.95), and higher neighborhood trust (OR 1.34; 95% CI 1.01-1.79), and with need factors, that is, poorer perception of health (OR 1.63; 95% CI 1.20-2.21), multiple comorbidities (OR 1.70; 95% CI 1.18-2.46), and higher number of prescribed medicines (OR 2.84; 95% CI 1.90-4.26). CONCLUSIONS: We found a high prevalence of OOPPE, identifying individuals more likely to incur these expenses. These findings are useful to inform policy makers from the healthcare system to plan and implement the needed interventions to protect primary care patients from this financial burden.

Two-colour light activated covalent bond formation.

We introduce a photochemical bond forming system, where two colours of light are required to trigger covalent bond formation. Specifically, we exploit a visible light cis/trans isomerization of chlorinated azobenzene, which can only undergo reaction with a photochemically generated ketene in its cis state. Detailed photophysical mapping of the reaction efficiencies at a wide range of monochromatic wavelengths revealed the optimum irradiation conditions. Subsequent small molecule and polymer ligation experiments illustrated that only the application of both colours of light affords the reaction product. We further extend the functionality to a photo reversible ketene moiety and translate the concept into material science. The presented reaction system holds promise to be employed as a two-colour resist.

Performance of a pharmaceutical services regionalization strategy policy in Minas Gerais, Brazil: Pre-post analysis from ERAF project.

Background: In 2016, the Brazilian state of Minas Gerais (∼20 million people), implemented the ERAF policy ("Regionalization Strategy of Pharmaceutical Services") in an effort to improve medicine procurement and distribution within primary care. We evaluated the impact of the policy on three main goals: price reductions, volume increases, and expansion of therapeutic options. Methods: We analyzed the procurement data from the Integrated System of Management of Pharmaceutical Services database in 2012 and 2018. We estimated the volume, drug mix, and expenditure indicators for all major therapeutic classes, and, in detail, for cardiovascular and nervous system drugs. We evaluated the expenditure drivers using decomposition analyses. Results: Overall, the expenditure increased by 14.5%, drug mix almost doubled, while the volume decreased by a third. Cardiovascular and neurological system drugs followed similar patterns. Decomposition analyses showed that prices and drug mix had positive effects while the volume had negative effects, resulting in an overall increase in expenditure. Conclusion: Our findings suggest that the ERAF policy cannot be considered effective as it has not fulfilled its intended purposes so far. Strategies to address the identified problems and to build a platform for a more sustainable long-lasting policy should be put in place by the government.

Algorithm for screening and management of locomotive syndrome in elderly individuals and development of a short version of the 25-question Geriatric Locomotive Function Scale-Portuguese.

OBJECTIVE: To develop a short version of the 25-question Geriatric Locomotive Function Scale-Portuguese and to create an algorithm for locomotive syndrome screening and management. METHODS: The 25-question Geriatric Locomotive Function Scale-Portuguese was applied to individuals aged 60 years or older seen at the Geriatrics and Gerontology Department of Universidade Federal de São Paulo, between 2016 and 2018. Items of the 25-question Geriatric Locomotive Function Scale-Portuguese were submitted to exploratory factor analysis using the principal component method. Internal consistency was investigated using Cronbach's alpha coefficient. The ROC curve was used to determine the cut-off point of the short version developed. Finally, a simple and objective algorithm was created for locomotive syndrome screening and management using the Delphi method. RESULTS: A total of 202 elderly individuals aged 61 to 101 years (mean age, 84.67 years) were evaluated. Fifteen items were excluded from the 25-question Geriatric Locomotive Function Scale-Portuguese to compose the 10-question Geriatric Locomotive Function Scale-Portuguese, a 10-item instrument with appropriate psychometric properties. A cut-off point of ten (ROC curve) was determined for potential locomotive syndrome, with 96.5% sensitivity and 86.2% specificity. A very simple algorithm was developed for locomotive syndrome screening and management. CONCLUSION: The short version (10-question) of the Geriatric Locomotive Function Scale-Portuguese has appropriate psychometric properties and provides a practical tool for detection of locomotive problems in elderly individuals.

Antibody response to a new member of the DBL family (EBP2) after a brief Plasmodium vivax exposure.

Plasmodium vivax blood-stage invasion into reticulocyte is critical for parasite development. Thus, validation of novel parasite invasion ligands is essential for malaria vaccine development. Recently, we demonstrated that EBP2, a Duffy binding protein (DBP) paralog, is antigenically distinct from DBP and could not be functionally inhibited by anti-DBP antibodies. Here, we took advantage of a small outbreak of P.vivax malaria, located in a non-malarious area of Brazil, to investigate for the first time IgM/IgG antibodies against EBP2 and DEKnull-2 (an engineering DBPII vaccine) among individuals who had their first and brief exposure to P.vivax (16 cases and 22 non-cases). Our experimental approach included 4 cross sectional surveys at 3-month interval (12-month follow-up). The results demonstrated that while a brief initial P.vivax infection was not efficient to induce IgM/ IgG antibodies to either EBP2 or DEKnull-2, IgG antibodies against DEKnull-2 (but not EBP2) were boosted by recurrent blood-stage infections following treatment. Of interest, in most recurrent P. vivax infections (4 out of 6 patients) DEKnull-2 IgG antibodies were sustained for 6 to 12 months. Polymorphisms in the ebp2 gene does not seem to explain EBP2 low immunogenicity as the ebp2 allele associated with the P.vivax outbreak presented high identity to the original EBP2 isolate used as recombinant protein. Although EBP2 antibodies were barely detectable after a primary episode of P.vivax infection, EBP2 was highly recognized by serum IgG from long-term malaria-exposed Amazonians (range from 35 to 92% according to previous malaria episodes). Taken together, the results showed that individuals with a single and brief exposure to P.vivax infection develop very low anti-EBP2 antibodies, which tend to increase after long-term malaria exposure. Finally, the findings highlighted the potential of DEKnull-2 as a vaccine candidate, as in non-immune individuals anti-DEKnull-2 IgG antibodies were boosted even after a brief exposure to P.vivax blood stages.