RESUMEN

Although anthropogenic activities are the primary drivers of increased greenhouse gas (GHG) emissions, it is crucial to acknowledge that wetlands are a significant source of these gases. Brazil's Pantanal, the largest tropical inland wetland, includes numerous lacustrine systems with freshwater and soda lakes. This study focuses on soda lakes to explore potential biogeochemical cycling and the contribution of biogenic GHG emissions from the water column, particularly methane. Both seasonal variations and the eutrophic status of each examined lake significantly influenced GHG emissions. Eutrophic turbid lakes (ET) showed remarkable methane emissions, likely due to cyanobacterial blooms. The decomposition of cyanobacterial cells, along with the influx of organic carbon through photosynthesis, accelerated the degradation of high organic matter content in the water column by the heterotrophic community. This process released byproducts that were subsequently metabolized in the sediment leading to methane production, more pronounced during periods of increased drought. In contrast, oligotrophic turbid lakes (OT) avoided methane emissions due to high sulfate levels in the water, though they did emit CO2 and N2O. Clear vegetated oligotrophic turbid lakes (CVO) also emitted methane, possibly from organic matter input during plant detritus decomposition, albeit at lower levels than ET. Over the years, a concerning trend has emerged in the Nhecolândia subregion of Brazil's Pantanal, where the prevalence of lakes with cyanobacterial blooms is increasing. This indicates the potential for these areas to become significant GHG emitters in the future. The study highlights the critical role of microbial communities in regulating GHG emissions in soda lakes, emphasizing their broader implications for global GHG inventories. Thus, it advocates for sustained research efforts and conservation initiatives in this environmentally critical habitat.

Asunto(s)

Gases de Efecto Invernadero , Lagos , Metano , Microbiota , Lagos/química , Lagos/microbiología , Gases de Efecto Invernadero/análisis , Brasil , Metano/análisis , Monitoreo del Ambiente , Humedales , Eutrofización , Contaminantes Atmosféricos/análisis

RESUMEN

Understanding and controlling polymorphism in molecular solids is a major unsolved problem in crystal engineering. While the ability to calculate accurate lattice energies with atomistic modelling provides valuable insight into the associated energy scales, existing methods cannot connect energy differences to the delicate balances of intra- and intermolecular forces that ultimately determine polymorph stability ordering. We report herein a protocol for applying Quantum Chemical Topology (QCT) to study the key intra- and intermolecular interactions in molecular solids, which we use to compare the three known polymorphs of succinic acid including the recently-discovered γ form. QCT provides a rigorous partitioning of the total energy into contributions associated with topological atoms, and a quantitative and chemically intuitive description of the intra- and intermolecular interactions. The newly-proposed Relative Energy Gradient (REG) method ranks atomistic energy terms (steric, electrostatic and exchange) by their importance in constructing the total energy profile for a chemical process. We find that the conformation of the succinic acid molecule is governed by a balance of large and opposing electrostatic interactions, while the H-bond dimerisation is governed by a combination of electrostatics and sterics. In the solids, an atomistic energy balance emerges that governs the contraction, towards the equilibrium geometry, of a molecular cluster representing the bulk crystal. The protocol we put forward is as general as the capabilities of the underlying quantum-mechanical model and it can provide novel perspectives on polymorphism in a wide range of chemical systems.

RESUMEN

The rhesus macaque provides a unique model of acquired immunity against schistosomes, which afflict >200 million people worldwide. By monitoring bloodstream levels of parasite-gut-derived antigen, we show that from week 10 onwards an established infection with Schistosoma mansoni is cleared in an exponential manner, eliciting resistance to reinfection. Secondary challenge at week 42 demonstrates that protection is strong in all animals and complete in some. Antibody profiles suggest that antigens mediating protection are the released products of developing schistosomula. In culture they are killed by addition of rhesus plasma, collected from week 8 post-infection onwards, and even more efficiently with post-challenge plasma. Furthermore, cultured schistosomula lose chromatin activating marks at the transcription start site of genes related to worm development and show decreased expression of genes related to lysosomes and lytic vacuoles involved with autophagy. Overall, our results indicate that enhanced antibody responses against the challenge migrating larvae mediate the naturally acquired protective immunity and will inform the route to an effective vaccine.

Asunto(s)

Schistosoma mansoni/fisiología , Esquistosomiasis mansoni/inmunología , Animales , Anticuerpos Antihelmínticos/inmunología , Anticuerpos Antihelmínticos/farmacología , Antígenos Helmínticos/inmunología , Modelos Animales de Enfermedad , Epigénesis Genética/efectos de los fármacos , Femenino , Genes de Helminto/genética , Granulocitos/inmunología , Histonas/metabolismo , Interacciones Huésped-Parásitos/inmunología , Larva/efectos de los fármacos , Larva/genética , Larva/crecimiento & desarrollo , Linfocitos/inmunología , Macaca mulatta/inmunología , Macaca mulatta/parasitología , Masculino , Recuento de Huevos de Parásitos , Reinfección/inmunología , Esquistosomiasis mansoni/parasitología

RESUMEN

The reaction path for the formation of BX3-NH3 (X = H, F, Cl, Br) complexes was divided into two processes: (i) rehybridization of the acid while adopting a pyramidal geometry, and (ii) the complex formation from the pyramidal geometries of the acid and base. The interacting quantum atom (IQA) method was used to investigate the Lewis acidity trend of these compounds. This topological analysis suggests that the boron-halogen bond exhibits a considerable degree of ionicity. A relative energy gradient (REG) analysis on IQA energies indicates that the acid-base complex formation is highly dependent on electrostatic energy. With increasing halogen electronegativity, a higher degree of ionicity of the B-X is observed, causing an increase in the absolute value of X and B charges. This increases not only the attractive electrostatic energy between the acid and base but also enhances the repulsive energy. The latter is the main factor behind the acidity trend exhibited by trihalides. Changes in geometry are relevant only for complexes where BH3 acts as an acid, where lower steric hindrance facilitates the adoption of the pyramidal geometry observed in the complex. The CCTDP analysis shows that infrared intensities of BX3-NH3 are determined mostly by the atomic charges and not by the charge transfer or polarization. The opposite is observed in covalent analogues.

RESUMEN

The rhesus macaque provides a unique model of acquired immunity against schistosomes, which afflict >200 million people worldwide. By monitoring bloodstream levels of parasite-gut-derived antigen, we show that from week 10 onwards an established infection with Schistosoma mansoni is cleared in an exponential manner, eliciting resistance to reinfection. Secondary challenge at week 42 demonstrates that protection is strong in all animals and complete in some. Antibody profiles suggest that antigens mediating protection are the released products of developing schistosomula. In culture they are killed by addition of rhesus plasma, collected from week 8 post-infection onwards, and even more efficiently with post-challenge plasma. Furthermore, cultured schistosomula lose chromatin activating marks at the transcription start site of genes related to worm development and show decreased expression of genes related to lysosomes and lytic vacuoles involved with autophagy. Overall, our results indicate that enhanced antibody responses against the challenge migrating larvae mediate the naturally acquired protective immunity and will inform the route to an effective vaccine.

RESUMEN

The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was funded in 2008 to conduct research that would support country schistosomiasis control programs. As schistosomiasis prevalence decreases in many places and elimination is increasingly within reach, a sensitive and specific test to detect infection with Schistosoma mansoni and Schistosoma haematobium has become a pressing need. After obtaining broad input, SCORE supported Leiden University Medical Center (LUMC) to modify the serum-based antigen assay for use with urine, simplify the assay, and improve its sensitivity. The urine assay eventually contributed to several of the larger SCORE studies. For example, in Zanzibar, we demonstrated that urine filtration, the standard parasite egg detection diagnostic test for S. haematobium, greatly underestimated prevalence in low-prevalence settings. In Burundi and Rwanda, the circulating anodic antigen (CAA) assay provided critical information about the limitations of the stool-based Kato-Katz parasite egg-detection assay for S. mansoni in low-prevalence settings. Other SCORE-supported CAA work demonstrated that frozen, banked urine specimens yielded similar results to fresh ones; pooling of specimens may be a useful, cost-effective approach for surveillance in some settings; and the assay can be performed in local laboratories equipped with adequate centrifuge capacity. These improvements in the assay continue to be of use to researchers around the world. However, additional work will be needed if widespread dissemination of the CAA assay is to occur, for example, by building capacity in places besides LUMC and commercialization of the assay. Here, we review the evolution of the CAA assay format during the SCORE period with emphasis on urine-based applications.

Asunto(s)

Antígenos Helmínticos/inmunología , Glicoproteínas/inmunología , Proteínas del Helminto/inmunología , Schistosoma/inmunología , Esquistosomiasis/diagnóstico , Animales , Biomarcadores , Burundi/epidemiología , Niño , Pruebas Diagnósticas de Rutina , Heces/parasitología , Femenino , Humanos , Pruebas Inmunológicas , Masculino , Modelos Animales , Papio/parasitología , Recuento de Huevos de Parásitos , Prevalencia , Rwanda/epidemiología , Santa Lucia/epidemiología , Schistosoma/aislamiento & purificación , Schistosoma haematobium/inmunología , Schistosoma haematobium/aislamiento & purificación , Schistosoma japonicum/inmunología , Schistosoma japonicum/aislamiento & purificación , Schistosoma mansoni/inmunología , Schistosoma mansoni/aislamiento & purificación , Esquistosomiasis/epidemiología , Sensibilidad y Especificidad , Tanzanía/epidemiología , Orina/parasitología

RESUMEN

Saint Lucia at one time had levels of schistosomiasis prevalence and morbidity as high as many countries in Africa. However, as a result of control efforts and economic development, including more widespread access to sanitation and safe water, schistosomiasis on the island has practically disappeared. To evaluate the current status of schistosomiasis in Saint Lucia, we conducted a nationally representative school-based survey of 8-11-year-old children for prevalence of Schistosoma mansoni infections using circulating antigen and specific antibody detection methods. We also conducted a questionnaire about available water sources, sanitation, and contact with fresh water. The total population of 8-11-year-old children on Saint Lucia was 8,985; of these, 1,487 (16.5%) provided urine for antigen testing, 1,455 (16.2%) provided fingerstick blood for antibody testing, and 1,536 (17.1%) answered the questionnaire. Although a few children were initially low positives by antigen or antibody detection methods, none could be confirmed positive by follow-up testing. Most children reported access to clean water and sanitary facilities in or near their homes and 48% of the children reported contact with fresh water. Together, these data suggest that schistosomiasis transmission has been interrupted on Saint Lucia. Additional surveys of adults, snails, and a repeat survey among school-age children will be necessary to verify these findings. However, in the same way that research on Saint Lucia generated the data leading to use of mass drug administration for schistosomiasis control, the island may also provide the information needed for guidelines to verify interruption of schistosomiasis transmission.

Asunto(s)

Anticuerpos Antihelmínticos/sangre , Esquistosomiasis/epidemiología , Esquistosomiasis/transmisión , Niño , Femenino , Humanos , Masculino , Factores de Riesgo , Santa Lucia/epidemiología , Saneamiento , Esquistosomiasis/prevención & control , Pruebas Serológicas , Encuestas y Cuestionarios

RESUMEN

Techniques with high sensitivity and specificity are required for an accurate diagnosis in low-transmission settings, where the conventional parasitological methods are insensitive. We determined the accuracy of an up-converting phosphor-lateral flow circulating anodic antigen (UCP-LF CAA) assay in urine and serum for Schistosoma mansoni diagnosis in low-prevalence settings in Ceará, Brazil, before and after praziquantel treatment. Clinical samples of a total of 258 individuals were investigated by UCP-LF CAA, point-of-care-circulating cathodic antigen (POC-CCA), soluble worm antigen preparation (SWAP)-ELISA and Kato-Katz (KK); a selection of 128 stools by real-time PCR technique. Three and 6-weeks after treatment, samples were collected and evaluated by detection Schistosoma circulating antigens (CAA and CCA). The UCP-LF CAA assays detected 80 positives (31%) with urine and 82 positives (31.8%) with serum. The urine POC-CCA and serum SWAP-ELISA assays detected 30 (11.6%) and 107 (40.7%) positives, respectively. The Kato-Katz technique revealed only 4 positive stool samples (1.6%). Among the 128 individuals with complete data records, 19 cases were identified by PCR (14.8%); Sensitivities and specificities of the UCP-LF CAA assays, determined versus a combined reference standard based on CCA/KK/PCR positivity, ranged from 60-68% to 68-77%, respectively. In addition only for comparative purposes, sensitivities of the different assays were determined vs. a comparative reference based on CAA/KK/PCR positivity, showing the highest sensitivity for the urine CAA assay (80%), followed by the serum CAA (70.9%), SWAP-ELISA (43.6%), PCR (34.5%), POC-CCA (29.1%), whilst triplicate Kato-Katz thick smears had a very low sensitivity (3.6%). CAA concentrations were higher in serum than in urine and were significantly correlated. There was a significant decrease in urine and serum CAA levels 3 and 6-weeks after treatment. The UCP-LF CAA assays revealed 33 and 28 S. mansoni-infected patients at the 3- and 6-week post-treatment follow-up, respectively. The UCP-LF CAA assays show high sensitivity for the diagnosis of S. mansoni in low-endemicity settings. It detects a considerably higher number of infections than microscopy, POC-CCA or PCR. Also it shows to be very useful for evaluating cure rates after treatment. Hence, the UCP-LF CAA assay is a robust and promising diagnostic approach in low-transmission settings.

Asunto(s)

Antígenos Helmínticos/inmunología , Pruebas Inmunológicas , Schistosoma mansoni/inmunología , Esquistosomiasis mansoni/diagnóstico , Esquistosomiasis mansoni/inmunología , Adolescente , Adulto , Anciano , Animales , Antígenos Helmínticos/sangre , Brasil/epidemiología , Niño , Preescolar , Humanos , Pruebas Inmunológicas/métodos , Pruebas Inmunológicas/normas , Estudios Longitudinales , Persona de Mediana Edad , Vigilancia de la Población , Prevalencia , Reproducibilidad de los Resultados , Schistosoma mansoni/genética , Esquistosomiasis mansoni/epidemiología , Esquistosomiasis mansoni/parasitología , Sensibilidad y Especificidad , Adulto Joven

RESUMEN

Leprosy remains persistently endemic in several low- or middle income countries. Transmission is still ongoing as indicated by the unabated rate of leprosy new case detection, illustrating the insufficiency of current prevention methods. Therefore, low-complexity tools suitable for large scale screening efforts to specifically detect M. leprae infection and diagnose disease are required. Previously, we showed that combined detection of cellular and humoral markers, using field-friendly lateral flow assays (LFAs), increased diagnostic potential for detecting leprosy in Bangladesh compared to antibody serology alone. In the current study we assessed the diagnostic performance of similar LFAs in three other geographical settings in Asia, Africa and South-America with different leprosy endemicity. Levels of anti-PGL-I IgM antibody (humoral immunity), IP-10, CCL4 and CRP (cellular immunity) were measured in blood collected from leprosy patients, household contacts and healthy controls from each area. Combined detection of these biomarkers significantly improved the diagnostic potential, particularly for paucibacillary leprosy in all three regions, in line with data obtained in Bangladesh. These data hold promise for the use of low-complexity, multibiomarker LFAs as universal tools for more accurate detection of M. leprae infection and different phenotypes of clinical leprosy.

Asunto(s)

Anticuerpos Antibacterianos/sangre , Antígenos Bacterianos/inmunología , Pruebas Inmunológicas/métodos , Lepra/diagnóstico , Mycobacterium leprae/inmunología , Adolescente , Adulto , Anciano , Brasil , Proteína C-Reactiva/metabolismo , Estudios de Casos y Controles , Quimiocina CCL4/sangre , Quimiocina CXCL10/sangre , Niño , China , Enfermedades Endémicas , Etiopía , Femenino , Humanos , Inmunidad Celular , Inmunidad Humoral , Lepra/sangre , Lepra/inmunología , Masculino , Persona de Mediana Edad , Sensibilidad y Especificidad , Factores Socioeconómicos , Adulto Joven

RESUMEN

When electronic correlation energy is partitioned topologically, a detailed picture of its distribution emerges, both within atoms and between any two atoms. This methodology allows one to study dispersion beyond its more narrow definition in long-range Rayleigh-Schrödinger perturbation theory. The interacting quantum atoms (IQA) method was applied to MP2/6-31G(d,p) (uncontracted) wave functions of a wide variety of systems: glycine…water (hydration), the ethene dimer (π-π interactions), benzene (aromaticity), cyclobutadiene (antiaromaticity), and NH3BH3 (dative bond). Through the study of molecular complexes it turns out that dispersion energy is either important to a system's stabilization (for the C2H4 dimer) or not important (for Gly…H2O). We have also discovered that the delocalization in benzene lowers the strength of Coulomb repulsion in the bonds, which has been quantified for the first time through IQA. Finally, we showed that the nature of the dative bond is much different from that of a regular covalent bond as it is not destabilized by electronic correlation. Finally, the conclusions obtained for these archetypical systems have implications for the future of the quantum topological force field FFLUX in the simulation of larger systems. Graphical abstract Atomic and bond dynamic correlation energies are now available thanks to IQA. Larger molecules can now be accessed to include resonance and solvation of FFLUX force field.

RESUMEN

Early detection of leprosy is key to reduce the ongoing transmission. Antibodies directed against M. leprae PGL-I represent a useful biomarker for detecting multibacillary (MB) patients. Since efficient leprosy diagnosis requires field-friendly test conditions, we evaluated two rapid lateral flow assays (LFA) for detection of Mycobacterium leprae-specific antibodies: the visual immunogold OnSite Leprosy Ab Rapid test [Gold-LFA] and the quantitative, luminescent up-converting phosphor anti-PGL-I test [UCP-LFA]. Test performance was assessed in independent cohorts originating from three endemic areas. In the Philippine cohort comprising patients with high bacillary indices (BI; average:4,9), 94%(n = 161) of MB patients were identified by UCP-LFA and 78%(n = 133) by Gold-LFA. In the Bangladeshi cohort, including mainly MB patients with low BI (average:1), 41%(n = 14) and 44%(n = 15) were detected by UCP-LFA and Gold-LFA, respectively. In the third cohort of schoolchildren from a leprosy hyperendemic region in Brazil, both tests detected 28%(n = 17) seropositivity. Both rapid tests corresponded well with BI(p < 0.0001), with a fairly higher sensitivity obtained with the UCP-LFA assay. However, due to the spectral character of leprosy, additional, cellular biomarkers are required to detect patients with low BIs. Therefore, the UCP-LFA platform, which allows multiplexing with differential biomarkers, offers more cutting-edge potential for diagnosis across the whole leprosy spectrum.

Asunto(s)

Anticuerpos Antibacterianos/inmunología , Lepra/diagnóstico , Lepra/inmunología , Mycobacterium leprae/inmunología , Pruebas en el Punto de Atención , Pruebas Serológicas/métodos , Antígenos Bacterianos/inmunología , Biomarcadores , Brasil , Ensayo de Inmunoadsorción Enzimática , Humanos , Curva ROC

RESUMEN

In 1976, 969 schoolchildren from the District of Saramacca in Surinam (age 4 to 16 years) were examined, especially the skin and mucous membranes. Blood samples were collected by venepuncture and skin samples were taken from individuals with lesions suggesting yaws. The diagnosis of yaws was based on a combination of epidemiological data, clinical findings, results of the VDRL test, histological evidence, and the effect of treatment with penicillin. The results showed that 212 children (22 per cent) had a reactive VDRL test, of which 29 children showed clinical lesions suggesting yaws. This indicated that yaws is prevalent (hypoendemic) in the District of Saramacca. No classical symptoms of Yaws were seen. The observed lesions were scanty or solitary, dry papillomateus, or macular and scaly, which fits into the clinical picture of attenuated endemic treponematosis

Asunto(s)

Niño , Resumen en Inglés , Humanos , Buba/epidemiología , Suriname/epidemiología

RESUMEN

This study was carried out in 1976 and 1977 to asses the value of cardiolipin and treponemal tests in the serodiagnosis of yaws. These tests were conducted on the sera of 661 children from a region where yaws is hypo-endemic. Results of the Venereal Disease Research Laboratory (VDRL), rapid plasma reagin (RPR), Treponema pallidum haemagglutination (TPHA), T. pallidum immobilisation (TPI), and fluorescent treponemal antibody absorption (FTA-ABS) tests were compared. The FTA-ABS test showed a weak reactivity (+) for 107 (16.2 per cent) sera and these children had no history and no signs or symptoms of treponemal disease. The FTA-ABS test can be used as a confirmatory test for yaws instead of the TPI test, if only the results of sera showing an intensity of fluorescence scored as ++ or more are considered to be positive. There appeared to be no significant differences in the results of the VDRL, RPR and TPHA tests as screening tests for yaws when the TPI or FTA-ABS tests were used as reference tests

Asunto(s)

Humanos , Niño , Resumen en Inglés , Estudio Comparativo , Cardiolipinas/diagnóstico , Prueba de Absorción de Anticuerpos Fluorescentes de Treponema/métodos , Buba/diagnóstico , Suriname/epidemiología

RESUMEN

Results of the treatment of Leishmania cutanea (South American) with Lomidin in 65 patients......(AU)

Asunto(s)

Resumen en Inglés , Humanos , Leishmania braziliensis/tratamiento farmacológico , Pentamidina/uso terapéutico , Suriname/epidemiología