High anti-SARS-CoV-2 antibody seroconversion rates before the second wave in Manaus, Brazil, and the protective effect of social behaviour measures: results from the prospective DETECTCoV-19 cohort

Background: The city of Manaus, Brazil, has seen two collapses of the health system due to the COVID-19 pandemic. We report anti-SARS-CoV-2 nucleocapsid IgG antibody seroconversion rates and associated risk factors in Manaus residents before the second wave of the epidemic in Brazil. Methods: A convenience sample of adult (aged ≥18 years) residents of Manaus was recruited through online and university website advertising into the DETECTCoV-19 study cohort. The current analysis of seroconversion included a subgroup of DETECTCoV-19 participants who had at least two serum sample collections separated by at least 4 weeks between Aug 19 and Oct 2, 2020 (visit 1), and Oct 19 and Nov 27, 2020 (visit 2). Those who reported (or had no data on) having a COVID-19 diagnosis before visit 1, and who were positive for anti-SARS-CoV-2 nucleocapsid IgG antibodies at visit 1 were excluded. Using an in-house ELISA, the reactivity index (RI; calculated as the optical density ratio of the sample to the negative control) for serum anti-SARS-CoV-2 nucleocapsid IgG antibodies was measured at both visits. We calculated the incidence of seroconversion (defined as RI values ≤1·5 at visit 1 and ≥1·5 at visit 2, and a ratio >2 between the visit 2 and visit 1 RI values) during the study period, as well as incidence rate ratios (IRRs) through cluster-corrected and adjusted Poisson regression models to analyse associations between seroconversion and variables related to sociodemographic characteristics, health access, comorbidities, COVID-19 exposure, protective behaviours, and symptoms. Findings: 2496 DETECTCoV-19 cohort participants returned for a follow-up visit between Oct 19 and Nov 27, 2020, of whom 204 reported having COVID-19 before the first visit and 24 had no data regarding previous disease status. 559 participants were seropositive for anti-SARS-CoV-2 nucleocapsid IgG antibodies at baseline. Of the remaining 1709 participants who were seronegative at baseline, 71 did not meet the criteria for seroconversion and were excluded from the analyses. Among the remaining 1638 participants who were seronegative at baseline, 214 showed seroconversion at visit 2. The seroconversion incidence was 13·06% (95% CI 11·52–14·79) overall and 6·78% (5·61–8·10) for symptomatic seroconversion, over a median follow-up period of 57 days (IQR 54–61). 48·1% of seroconversion events were estimated to be asymptomatic. The sample had higher proportions of affluent and higher-educated people than those reported for the Manaus city population. In the fully adjusted and corrected model, risk factors for seroconversion before visit 2 were having a COVID-19 case in the household (IRR 1·49 [95% CI 1·21–1·83]), not wearing a mask during contact with a person with COVID-19 (1·25 [1·09–1·45]), relaxation of physical distancing (1·31 [1·05–1·64]), and having flu-like symptoms (1·79 [1·23–2·59]) or a COVID-19 diagnosis (3·57 [2·27–5·63]) between the first and second visits, whereas working remotely was associated with lower incidence (0·74 [0·56–0·97]). Interpretation: An intense infection transmission period preceded the second wave of COVID-19 in Manaus. Several modifiable behaviours increased the risk of seroconversion, including non-compliance with non-pharmaceutical interventions measures such as not wearing a mask during contact, relaxation of protective measures, and non-remote working. Increased testing in high-transmission areas is needed to provide timely information about ongoing transmission and aid appropriate implementation of transmission mitigation measures. Funding: Ministry of Education, Brazil; Fundação de Amparo à Pesquisa do Estado do Amazonas; Pan American Health Organization (PAHO)/WHO.World Health OrganizationRevisión por pare

Funcionamento hidráulico e vulnerabilidade à seca de duas florestas tropicais

Orientador: Rafael Silva OliveiraTese (doutorado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: Florestas tropicais exercem um papel fundamental na regulação do clima regional e global. Nas últimas décadas, eventos de seca extrema têm causado ampla mortalidade de árvores nesses ecossistemas, e há uma previsão de que esses eventos aumentem nos próximos anos. O impacto da seca na vegetação, não depende apenas de mudanças na disponibilidade de água, mas também de atributos da vegetação que influenciam na sua resposta a essas mudanças. Dessa forma, a compreensão da diversidade de atributos hidráulicos, e da resposta à seca que varia com esses atributos, é essencial para podermos predizer os efeitos das mudanças globais sobre a vegetação, processos ecossistêmicos e seus feedbacks no clima regional e global. Sendo assim, essa tese teve como objetivo avaliar a diversidade funcional hidráulica em ecossistemas de florestas tropicais, a coordenação entre diferentes atributos hidráulicos e os trade-offs envolvidos na evolução desses atributos; além de discutir a resistência à seca das espécies como um determinante da resiliência de florestas tropicais a mudanças climáticas. Nós estudamos duas áreas na Amazônia (com diferente sazonalidade) e uma área em Floresta nebular. Em cada comunidade, encontramos uma diversidade de atributos hidráulicos, que refletirá em diferentes respostas às mudanças no clima. Essas estratégias hidráulicas variaram em um contínuo de segurança e eficiência de transporte de água, que está associado a história de vida e evolução de cada espécie. Nós observamos também que as árvores maiores são a mais vulneráveis a falha hidráulica em condições de seca mais severa. Esse resultado sugere que se essas florestas passarem por condições extremas de seca e aumento de temperatura, elas podem sofrer uma ampla mortalidade de árvores o que provocaria uma mudança radical na sua estrutura, alterando suas funções ecossistêmicas, como fluxo de água e carbonoAbstract: Tropical forests have a fundamental role on the regional and global climate. In the last decades, extreme drought events have caused considerable tree mortality worldwide, and these extreme events are predicted to increase in the next years. The drought effect on ecosystems depends not only on changes in water availability, but also on vegetation traits, which influence their response to such changes. Thus, the understanding of hydraulic traits diversity and the species-specific drought responses are important to predict global changes effects on vegetation dynamics, ecosystems process and their feedback in regional and global climate. Thus, our aims with this thesis is to provide information about the hydraulic functional diversity in tropical forests ecosystems, the coordination across different hydraulic traits, the trade-offs involved on their evolution, and discuss drought resistance as an important determinant on tropical forest resilience to climatic changes. We studied two sites in Amazon tropical forest (with contrasting precipitation patterns) and one site in Cloud Forest. We found a diversity of hydraulic functioning, indicating that within the same forest we will find different responses to the predicted climatic changes. The hydraulic strategies varied through a continuum of hydraulic security and water transport efficiency, which can be related to a long process of taxa evolution. The fact that taller trees are more hydraulically vulnerable indicates that if these forests go though higher drought conditions and temperature increase, they could experience a massive tree mortality that will promote changes on forest structure, changing the ecosystem functions, such as water fluxes and carbon storageDoutoradoEcologiaDoutora em Ecologia2011/52072-0FAPESPCAPE

Bioactivity of an Experimental Dental Implant with Anodized Surface

Background: Several studies proved that anodic oxidation improves osseointegration. This study aimed to optimize osseointegration through anodization in dental implants, obtaining anatase phase and controlled nanotopography. Methods: The division of the groups with 60 titanium implants was: control (CG); sandblasted (SG); anodized (AG): anodized pulsed current (duty cycle 30%, 30 V, 0.2 A and 1000 Hz). Before surgery, surface characterization was performed using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray Dispersive Energy Spectroscopy (EDS) and Raman Spectroscopy. For in vivo tests, 10 New Zealand white rabbits received an implant from each group. The sacrifice period was 2 and 6 weeks (n = 5) and the specimens were subjected to computed microtomography (μCT) and reverse torque test. Results: AFM and SEM demonstrated a particular nanotopography on the surface in AG; the anatase phase was proved by Raman spectroscopy. In the μCT and in the reverse torque test, the AG group presented better results than the other groups. Conclusion: The chemical composition and structure of the TiO2 film were positively affected by the anodizing technique, intensifying the biological characteristics in osseointegration

Hydraulic traits explain differential responses of Amazonian forests to the 2015 El Niño-induced drought

Reducing uncertainties in the response of tropical forests to global change requires understanding how intra- and interannual climatic variability selects for different species, community functional composition and ecosystem functioning, so that the response to climatic events of differing frequency and severity can be predicted. Here we present an extensive dataset of hydraulic traits of dominant species in two tropical Amazon forests with contrasting precipitation regimes – low seasonality forest (LSF) and high seasonality forest (HSF) – and relate them to community and ecosystem response to the El Niño–Southern Oscillation (ENSO) of 2015. Hydraulic traits indicated higher drought tolerance in the HSF than in the LSF. Despite more intense drought and lower plant water potentials in HSF during the 2015-ENSO, greater xylem embolism resistance maintained similar hydraulic safety margin as in LSF. This likely explains how ecosystem-scale whole-forest canopy conductance at HSF maintained a similar response to atmospheric drought as at LSF, despite their water transport systems operating at different water potentials. Our results indicate that contrasting precipitation regimes (at seasonal and interannual time scales) select for assemblies of hydraulic traits and taxa at the community level, which may have a significant role in modulating forest drought response at ecosystem scales. © 2019 The Authors. New Phytologist © 2019 New Phytologist Trus

Comportamento germinativo de duas esp\ue9cies de canga ferr\uedfera: Baccharis retusa DC. (Asteraceae) e Tibouchina multiflora Cogn. (Melastomataceae)

O objetivo desse estudo foi avaliar o comportamento germinativo de Bacccharis retusa e Tibouchina multiflora, espécies que ocorrem na vegetação de canga no Quadrilátero Ferrífero de Minas Gerais. Diásporos coletados no município de Barão de Cocais foram colocados para germinar nas temperaturas de 15, 20, 25 e 30 ºC na presença de luz contínua ou no escuro. As sementes mantidas inicialmente no escuro foram posteriormente transferidas para a presença de luz, mantendo-se as mesmas temperaturas. Os diásporos das duas espécies apresentaram comportamento fotoblástico positivo, com germinação inexpressiva no escuro em todas as temperaturas testadas. Na presença de luz contínua as sementes de T. multiflora não apresentaram diferenças na porcentagem final de germinação em todas as temperaturas testadas, mas B. retusa apresentou menor porcentagem final de germinação a 30 ºC. Os diásporos das duas espécies mantidos inicialmente no escuro, germinaram rapidamente após serem transferidos para luz branca contínua. Entretanto, não foi verificado efeito significativo do tempo de permanência no escuro nos valores finais de porcentagem de germinação alcançados a cada temperatura. Esses resultados sugerem que essas duas espécies de canga apresentam potencial para a formação de banco de sementes no solo