Search Results (83)

Background: Studies on the association between cognitive and physical fitness in older adults from particularly vulnerable settings are scarce. This study aims to analyse the relationship between different protocols for assessing physical fitness and the cognitive function of low-income older adults. Methods: A total of 312 adults aged 60–96 years (M age = 72.63, SD= 7.81) living in the urban area of Amazonas, Brazil, participated in the study. The following measures of physical fitness were assessed: body composition, handgrip strength, the Five Times Sit-to-Stand Test and Senior Fitness Tests. Cognitive function was assessed using the Mini-Mental State Examination (MMSE). Linear regression models were used to analyse the relationship between physical function measures and cognitive function. Results: For men, only the 30-chair stand test power (β = 0.33, p < 0.001) presented favourable association with cognitive function. For women, significant associations between MMSE score were observed for every fitness test, except for the chair sit-and-reach test. Conclusions: Physical fitness is differently associated with cognitive function among low-income older men and women from Amazonas. Muscular fitness particularly seems to be an important indicator of cognitive function. It should be considered for monitoring, promoting, and managing health-ageing of low-income elderly populations of both sexes. Full article

The present study has applied a probabilistic oil spill modeling framework to assess the potential risks associated with offshore oil spills in the Foz do Amazonas sedimentary basin, a region of exceptional ecological importance and increasing geopolitical and socio-environmental relevance. By integrating a large ensemble of simulations with validated hydrodynamic, atmospheric and wave-driven forcings, the analysis of said simulations has provided a robust and seasonally resolved assessment of oil drift and beaching patterns along the Guianas and the Brazilian Equatorial Margin. The model has presented a total of 47,500 simulations performed on 95 drilling sites located across the basin, using the Lagrangian Spill, Transport and Fate Model (STFM) and incorporating a six-year oceanographic and meteorological variability. The simulations have included ocean current fields provided by HYCOM, wind forcing provided by GFS and Stokes drift provided by ERA5. Model performance has been evaluated by comparisons with satellite-tracked surface drifters using normalized cumulative Lagrangian separation metrics and skill scores. Mean skill scores have reached 0.98 after 5 days and 0.95 after 10 days, remaining above 0.85 up to 20 days, indicating high reliability for short to intermediate forecasting horizons and suitability for probabilistic applications. Probabilistic simulations have revealed a pronounced seasonal effect, governed by the annual migration of the Intertropical Convergence Zone (ITCZ). During the JFMA period, shoreline impact probabilities have exceeded 40–50% along extensive portions of the French Guiana and Amapá state (Brazil) coastlines, with oil reaching the coast typically within 10–20 days. In contrast, during the JASO period, beaching probabilities have decreased to below 15%, accompanied by a substantial reduction in impact along the coastline and higher variability in arrival times. Although coastal exposure has been markedly reduced during JASO, a residual probability of approximately 2% of oil intrusion into the Amazonas river mouth has persisted. Full article

This study investigated proteomic differences in nasopharyngeal swabs of SARS-CoV-2-infected patients from Manaus (Brazil) who were hospitalized during the devastating first wave of the COVID-19 pandemic, before the emergence of the deadly P1 SARS-CoV-2 strain. LC-MS/MS proteomic analysis compared 16 matched COVID-19 patient profiles: eight survivors and eight fatalities. A total of 1604 proteins were identified in fatality swabs, and 981 in the swabs of survivors. Our study provides new insights into the cellular mechanisms underlying first-wave COVID-19 deaths from Manaus and identifies hypoxia-related HYOU1, endothelial injury-associated S100A10, and some viral replication proteins (DDX1/17, XPO1) as potential biomarkers of fatal infections. The proteomic profiles of the swabs taken from patients that died collectively suggest that many of the first wave COVID-19 fatalities in Manaus suffered immune-system collapse. Survivor patient swabs showed elevated levels of immune defense proteins (FN1, C4BPA, IGKV1-5), indicating effective antiviral responses. Gene ontology analysis revealed dysregulated secretory pathways in fatalities and did not detect the defense-response pathways in fatality-group datasets that were observed in survivor protein datasets. Interestingly, the NOS2 protein, previously associated with first-wave fatalities, was found exclusively in our fatality swabs. Full article

Background: The functional capacity of older adults is a critical determinant of autonomy and quality of life, particularly in low-income populations from remote regions with limited access to health services. This study aimed to characterize the functional fitness (FF) of community-dwelling older adults in the interior of Amazonas, Brazil, stratified by sex and age group. Methods: A cross-sectional study was conducted with 807 older adults (471 females), aged ≥ 60 years, from four municipalities in northern Brazil. The FF was assessed using the Senior Fitness Test (SFT), including measures of strength (30-s Chair Stand Test—CST; 30-s Arm Curl Test—ACT), flexibility (Chair Sit and Reach Test-CSAR, Back Scratch Test-BST), balance/agility (8-Foot Up-and-Go Test—FUG), and aerobic endurance (6-min walk test—6MWT). Descriptive statistics, confidence intervals, and age- and sex-specific percentiles were calculated. Results: Results indicated a progressive decline in FF with advancing age. Males outperformed females in strength and endurance tests, whereas females exhibited better flexibility. Notable reductions in performance were observed after age 75, particularly in CST, ACT, FUG, and 6MWT. Overall, the functional profiles of this population were below international norms, especially among females and individuals aged ≥ 80. The prevalence of overweight was 39.3%, with socioeconomic vulnerability affecting over 90% of participants. Conclusions: Older adults in low-income, remote Amazonian Brazilian communities demonstrate marked functional decline with ageing, influenced by socioeconomic and environmental constraints. These findings highlight the urgency of implementing accessible, community-based interventions focused on physical activity, strength, mobility, and endurance to support healthy ageing in underserved regions. Full article

Brazil is the first of the 12 priority countries in Latin America with the highest number of cases of American cutaneous leishmaniasis (ACL). This study estimated the prevalence of ACL in Brazil and classified the states according to the different levels of endemicity in the period from 2014 to 2024. This is a retrospective and cross-sectional study of ACL cases registered in Brazil by the Information System for Notifiable Diseases of the Ministry of Health. The predominant cases were male (73.2%), brown (65.0%), aged between 20 and 39 (41.5%), with a low level of education (44.4%), 0.5% in pregnant women, 80% of cases were confirmed by laboratory criteria, and 90% were classified as cutaneous. A total of 182,072 autochthonous cases were recorded, with a prevalence of 89.6 cases per 100,000 population. Two states were classified as having high intense endemicity; three were classified as having medium intense endemicity; four were classified as having low intense endemicity; five states were classified as having moderate endemicity; and 13 were classified as having low endemicity. The municipality of Presidente Figueiredo, Amazonas, had the highest prevalence of ACL (5503.1%), while Belo Horizonte had the lowest prevalence (72.2%). The month with the highest average number of cases was January with 1731 (with a standard deviation of 364; upper limit of 1933; lower limit of 1572). The heterogeneity of endemicity among States suggests that social and environmental determinants influence the dynamics of ACL transmission. All sociodemographic, clinical, and epidemiological categories, when compared with the different levels of endemicity, showed significant effects (p < 0.05), except for the variable gestational status in high disease endemicity. The inclusion of these variables significantly improved the model’s ability to predict the dependent variable. Full article

The objective was to evaluate the quality of an instrument to measure the experience of household water insecurity (WI) and the factors associated with the prevalence of WI in an urban area in a municipality in the Western Brazilian Amazon. A cross-sectional, population-based study was conducted to investigate 983 urban households. The Household Water Insecurity Experiences (HWISE) scale was used to measure the psychometric properties of reliability and validity. An exploratory factor analysis was conducted, and the prevalence ratio (PR, 95% CI) was calculated, considering WI as the dependent variable and the other household variables as independent variables. WI affected 46.2% (95% CI: 43.0–49.4%) of the households, independently associated with: head of the family as parent/other and presence of a child in the household. The instrument exhibited unidimensionality in the factor analyses and was considered to be both reliable and valid, as indicated by a Cronbach’s α coefficient of 0.958. Household WI is a serious public health problem in the Amazon in correlation with both social vulnerability and a lack of public services. As a preliminary approach, the scale proved to be valid and reliable. However, considering the Amazonian context, misunderstandings about some issues by respondents were identified, and further validation studies are needed to improve the intelligibility of these questions. Full article

Two new miniature tetra species of the genus Priocharax Weitzman and Vari 1987 are described, raising the known species diversity to twelve. Priocharax is characterized by several paedomorphic features such as reductions in the laterosensory system, number of fin rays, ossification of parts of the skull and the presence of a larval rayless pectoral fin in adults. The species described are found in the Rio Purus and Solimões drainages, in the state of Amazonas, Brazil and are diagnosed among themselves and from other species of the genus by the combination of meristic and osteological characters. Furthermore, the two species differ in overall body shape, with one having a deeper body and the other a more streamlined form. Sexual dimorphism was observed in both species. Molecular species delimitation analyses support the distinctiveness of these species. Similarly to Priocharax britzi and to P. conwayi, the specimens analyzed here were collected within and around protected areas, highlighting the importance of these areas for conservation and biodiversity knowledge. Full article

Honey is a natural product produced by bees from the nectar of plants and has been widely used as a sweetener for centuries. In addition to its traditional use, it is also employed for other purposes due to its biological and nutraceutical properties. Although honey production is mostly associated with bees of the genus Apis, species from other genera, such as Melipona, also produce it, albeit on a smaller scale. The honey produced by these two genera shows significant differences in its composition. Moreover, distinct geographical localizations, which, consequently, have different flora, guide the chemical compositions of these samples. Regarding the Amazon region, the amount of knowledge about the honey samples from Melipona species is still scarce. In this context, the present study aimed to characterize the volatile compositions of honey from Melipona interrupta and Melipona seminigra, as well as from the floral sources available, in addition to evaluating their nutritional aspects, antioxidant activity, and antibacterial activity. The analysis of chemical composition was performed using gas chromatography coupled to mass spectrometry (GC-MS). Antioxidant activity was determined by DPPH and ABTS assays, while antimicrobial activity was tested against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus epidermidis, Enterococcus faecalis, Salmonella enterica, Serratia marcescens, Bacillus subtilis, Candida albicans, Candida tropicalis, and Candida parapsilosis. The results allowed the identification of volatiles present in the honey and floral sources. The samples displayed moderate antioxidant activity and slightly antibacterial activity (MIC) of 75 μg/mL against two bacterial strains tested, demonstrating potential antimicrobial activity. Full article

The Amazon rainforest hosts a diverse array of forest types, including those where Brazil nut (Bertholletia excelsa) occurs, which plays a crucial ecological and economic role. The Brazil nut is the second most important non-timber forest product in the Amazon, a symbol of development and sustainable use in the region, promoting the conservation of the standing forest. Understanding the vertical structure of these forests is essential to assess their ecological complexity and inform sustainable management strategies. We used terrestrial laser scanning (TLS) to assess the vertical structure of Amazonian forests with the occurrence of Brazil nut (Bertholletia excelsa) at regional (Amazonas, Mato Grosso, Pará, and Amapá) and local scales (forest typologies in Amapá). TLS allowed high-resolution three-dimensional characterization of canopy layers, enabling the extraction of structural metrics such as canopy height, rugosity, and leaf area index (LAI). These metrics were analyzed to quantify the forest vertical complexity and compare structural variability across spatial scales. These findings demonstrate the utility of TLS as a precise tool for quantifying forest structure and highlight the importance of integrating structural data in conservation planning and forest monitoring initiatives involving B. excelsa. Full article

Miraruira is a medicinal plant-based product (MPBP) that is widely used in the state of Amazonas for the treatment of diabetes, though its botanical identity remains unclear, which raises concerns about authenticity and therapeutic consistency. One solution to this problem is the use of mass spectrometry-based approaches, which have emerged as powerful tools for verifying botanical origin based on chemical composition. Thus, to confirm the botanical authenticity of miraruira, direct-injection mass spectrometry (DI-MS) and chemometric analyses (PCA and HCA) were conducted on methanol fractions of Salacia impressifolia and Connarus ruber, both suspected sources of miraruira, as well as commercial samples obtained in street markets in Manaus, Brazil. Additionally, the hexane extracts of C. ruber and the commercial samples were screened for benzoquinones using DI-MS, as these compounds are recurrent in the genus Connarus. The DI-MS and PCA analyses revealed distinct chemical profiles for each species, and identified mangiferin and epicatechin as chemical markers for S. impressifolia and C. ruber, respectively. Furthermore, PCA demonstrated that all the commercial samples exhibited chemical profiles closely aligned with C. ruber. However, the HCA indicated variability among these samples, suggesting C. ruber or related Connarus species are the primary sources of miraruira. Moreover, embelin, rapanone, and suberonone were identified as the main compounds in the hexane extracts of C. ruber and the commercial products. This study successfully confirmed the botanical authenticity of miraruira, identified key bioactive compounds related to its traditional use in the treatment of diabetes symptoms, and demonstrated the effectiveness of DI-MS as a valuable tool for addressing authenticity issues in MPBPs. Full article

Malaria remains a health problem, with Plasmodium falciparum accounting for 96% of cases in Africa and 15% in Brazil. The growing threat of drug resistance to artemisinin-based combination therapies (ACTs) jeopardizes progress toward elimination. This study examined P. falciparum samples collected from 141 patients in Brazil (2013–2023) by PCR and DNA sequencing to identify single-nucleotide polymorphisms in the pfcrt, pfmdr1, and pfk13 genes. Half of the samples carried the SVMNTMCGI haplotype in pfcrt, and none of the samples showed C350R mutations. In pfmdr1, the NYCDY haplotype was dominant (70%), with low occurrences of N86Y (4%) and no Y184F polymorphisms. No mutations linked to artemisinin partial resistance were detected in pfk13. Only one Amazonas sample exhibited wild-type haplotypes across all genes. Genetic diversity was more pronounced in pfcrt than pfmdr1, reflecting selective drug pressure. Significant linkage disequilibrium (LD) was observed within pfcrt (C72S and K76T) and pfmdr1 (S1034C and N1042D), but not between the two genes. The absence of pfk13-resistant mutations and the low prevalence of key pfmdr1 markers support the efficacy of ACTs. The persistence of diverse haplotypes and intragenic LD reflects ongoing drug pressure, underscoring the need for continuous genetic surveillance to anticipate emerging resistance. Full article

The northern region of Brazil is endemic for American Tegumentary Leishmaniasis (ATL) primarily caused by Leishmania guyanensis and transmitted by the sand fly Nyssomyia umbratilis. The disease occurs at different rates in the municipalities of Manacapuru (MAN) and Rio Preto da Eva (RPE), located in the state of Amazonas. Despite their geographic proximity and separation by the Rio Negro, MAN has a low incidence, whereas RPE reports a significantly higher number of cases. Since the vector is present in both locations, potential biological differences in N. umbratilis may influence transmission. Previous studies suggested genotypic and phenotypic differences in N. umbratilis from both localities. To investigate the molecular factors underlying their potentially differential vectorial capacities, we performed a comparative proteomic analysis of dissected insect intestines from both localities. Our results revealed that sand flies from MAN showed a higher abundance of proteins related to gene transcription, protein translation, amino acid and proton transport, innate immune response and intestinal motility. Since the importance of microbiota has previously been shown in parasite–vector interactions, we also identified bacteria from both vector populations. We detected bacteria specific to each population and, exclusively in MAN, some species described in the literature as having parasiticidal properties. These findings highlight molecular and microbial peculiarities that could contribute to the observed difference in ATL prevalence in the two areas. Full article

Trichomitus batrachorum is a species of trichomonad that has gained attention due to its ecological importance and potential interactions with various hosts, such as amphibians (anurans) and reptiles (lizards and chelonians), where it has been recorded in the gastrointestinal tract of these vertebrates, specifically in their feces. Molecular studies have placed this flagellated protist within the Metamonada clade. Unlike parabasalids that inhabit endothermic mammals in relatively stable temperature conditions, protists associated with ectothermic reptiles are subject to significant temperature fluctuations. The ability of T. batrachorum to thrive in the variable temperatures encountered by reptiles suggests that its parasitism may remain largely unaffected by climate change. In our study, we detected and characterized T. batrachorum from the liver tissue of the lizard species Ameiva ameiva, collected in Presidente Figueiredo Municipality, Amazonas State, Brazil. The identification of T. batrachorum was confirmed by cultivation technique, light microscopy, scanning electron microscopy and transmission electron microscopy for ultrastructural analyses, and sequencing the 5.8S rDNA (region ITS1- ITS2) and 18S rRNA (ribosomal RNA) genes. One potential interpretation for this finding is that the flagellates may have migrated from the intestine to the bile duct, ultimately reaching the liver. This is the first successful characterization of T. batrachorum in the liver of a lizard, and provides a solid foundation for further research to elucidate the potential pathogenicity of this flagellate and the role of A. ameiva in the epidemiology of parabasalids in other animal species. Full article

This study investigates pegmatites with exceptionally rare mineralogical and chemical signatures, hosted by the 1.8 Ga peralkaline albite-enriched granite, which corresponds to the renowned Madeira Sn-Nb-Ta-F (REE, Th, U) deposit in Pitinga, Brazil. Four distinct pegmatite types are identified: border pegmatites, pegmatitic albite-enriched granite, miarolitic pegmatite, and pegmatite veins. The host rock itself has served as the source for the fluids that gave rise to all these pegmatites. Their mineral assemblages mirror the rare-metal-rich paragenesis of the host rock, including pyrochlore, cassiterite, riebeckite, polylithionite, zircon, thorite, xenotime, gagarinite-(Y), genthelvite, and cryolite. These pegmatites formed at the same crustal level as the host granite and record a progressive magmatic–hydrothermal evolution driven by various physicochemical processes, including tectonic decompressing, extreme fractionation, melt–melt immiscibility, and internal fluid exsolution. Border pegmatites crystallized early from a F-poor, K-Ca-Sr-Zr-Y-HREE-rich fluid exsolved during solidification of the pluton’s border and were emplaced in contraction fractures between the pluton and country rocks. Continued crystallization toward the pluton’s core produced a highly fractionated melt enriched in Sn, Nb, Ta, Rb, HREE, U, Th, and other HFSE, forming pegmatitic albite-enriched granite within centimetric fractures. A subsequent pressure quench—likely induced by reverse faulting—triggered the separation of a supercritical melt, further enriched in rare metals, which migrated into fractures and cavities to form amphibole-rich pegmatite veins and miarolitic pegmatites. A key process in this evolution was melt–melt immiscibility, which led to the partitioning of alkalis between two phases: a K-F-rich aluminosilicate melt (low in H₂O), enriched in Y, Li, Be, and Zn; and a Na-F-rich aqueous melt (low in SiO₂). These immiscible melts crystallized polylithionite-rich and cryolite-rich pegmatite veins, respectively. The magmatic–hydrothermal transition occurred independently in each pegmatite body upon H₂O saturation, with the hydrothermal fluid composition controlled by the local degree of melt fractionation. These highly F-rich exsolved fluids caused intense autometasomatic alteration and secondary mineralization. The exceptional F content (up to 35 wt.% F in pegmatite veins), played a central role in concentrating strategic and critical metals such as Nb, Ta, REEs (notably HREE), Li, and Be. These findings establish the Madeira system as a reference for rare-metal magmatic–hydrothermal evolution in peralkaline granites. Full article

It is important to understand which bacterial taxa are most abundant during SARS-CoV-2 infection and to promote mitigation strategies for conditions subsequent to infection. Nasopharyngeal swab samples were collected from patients infected with SARS-CoV-2 and their family contacts (uninfected and asymptomatic) during the outbreak of the P.1 variant of SARS-CoV-2 in Parintins, Amazonas–Brazil, in March 2021. The samples were investigated by a shotgun sequencing metagenomic approach using the NextSeq 500 Illumina® system. The samples were stratified according to the presence or absence of SARS-CoV-2, household group, sex, and age. Of the total of 63 individuals, 37 (58.73%) were positive for SARS-CoV-2 and 26 (41.27%) were negative for SARS-CoV-2 and other respiratory viruses (FLU, AdV, HBoV, HCoV, HMPV, RSV, PIV, HRV). The alpha diversity indexes Chao1, species observed, Simpson, and Inv Simpson demonstrated a significant difference (p < 0.05) in both the diversity of observed species and the abundance of some taxa between positive and negative individuals. We also observed an abundance of opportunists such as Klebsiella pneumoniae, Staphylococcus spp, and Shigella sonnei, previously associated with the severity of COVID-19. Our results suggest that SARS-CoV-2 infection causes changes in the microenvironment of the nasopharyngeal region, allowing greater proliferation of opportunistic bacteria and decreased abundance of commensal bacteria. Full article