Uterotonic agents for preventing postpartum haemorrhage:a network meta-analysis (Protocol)

Brathys e Trigynobrathys (88 e 59 representantes, respectivamente) são as duas maiores seções do gênero Hypericum que são distribuídos principalmente na América Central e América do Sul. Das mais de 100 espécies sul-americanas de Hypericum quase 65 são endêmicas dos Páramos, ecossistemas de alta altitude, caracterizados por uma vegetação composta principalmente de plantas de roseta gigantes, arbustos e gramíneas, nos quais Hypericum é um componente importante. Tendo em vista o escasso conhecimento da fitoquímica destas espécies de Hypericum, o presente estudo teve como objetivo estudar a composição fitoquímica e algumas bioatividades de seis espécies de Hypericum nativas do Peru (H. aciculare, H. andinum, H. brevistylum, H. decandrum, H. laricifolium e H. silenoides). O material vegetal, seco ao ar, das seis espécies (partes aéreas, caules, folhas e flores), e material vegetal subterrâneo de H. andinum (raízes e caules), foram moídas e extraídas por maceração à temperatura ambiente com n-hexano. Além disso, foram obtidos extrato etanólicos a partir de quatro espécies (H. andinum, H. brevistylum, H. laricifolium e H. silenoides). Os extratos n-hexano foram fracionados e as frações foram sometidas a processos cromatográficos obtendo-se cinco derivados de floroglucinol diméricos conhecidos, uliginosina A, uliginosina B, isouliginosina B, hiperbrasilol B e isohiperbrasilol B. Além disso, foram identificadas duas estruturas monoméricas e duas diméricas inéditas em H. andinum (raízes) e em H. laricifolium, andinina A, hiperlaricifolina A, laricifolina A e laricifolina B. Andinina A mostrou potencial atividade antidepressiva no teste de natação forçada. Do mesmo modo, a atividade antidepressiva dos extratos etanólicos foi avaliada. Estes quatro extratos apresentaram potencial atividade antidepressiva. As análises fitoquímicas por TLC, HPLC-DAD e UPLC-DAD/Q-TOF-MS revelaram que estes extratos são ricos em flavonoides, principalmente hiperosídeo. Os extratos n-hexano foram também analisados por um novo método de HPLC-DAD associado a LC-MS e UPLC-Q-TOF-MS . A presença de homólogos superiores M + 14 e regioisómeros foi determinada. A ocorrência natural destes cinco floroglucinois homólogos superiores M + 14 é descrita e a presença de outros compostos identificados pelo padrão de fragmentação MS é apresentada. Estes extratos e o seu principal componente foram capazes de inibir potencialmente a quimiotaxia induzida por LPS. Estes resultados sugerem que os extratos de espécies de Hypericum das seções Brathys e Trigynobrathys são fontes potenciais de novos anti-inflamatórios e antidepressivos.Brathys and Trigynobrathys (88 and 59 representatives, respectively) are the two largest sections of the genus Hypericum that are principally distributed in Central and South America. Of the more than 100 South American species of Hypericum almost 65 are endemic to the Páramos, high-altitude grassland ecosystems characterized by vegetation composed mainly of giant rosette plants, shrubs and grasses, in which Hypericum is a prominent component. In view of the scare knowledge on the phytochemistry of these Hypericum species, the present research aimed to study the phytochemical composition and some bioactivities of six Peruvian Hypericum species (H. aciculare, H. andinum, H. brevistylum, H. decandrum, H. laricifolium and H. silenoides). The air-dried aerial plant material of those six species (stems, leaves and flowers), and underground plant material of H. andinum (roots and stems), were ground and extracted by maceration at room temperature with n-hexane. Additionally crude ethanolic extracts were obtained from four species (H. andinum, H. brevistylum, H. laricifolium and H. silenoides). The n-hexane extracts were fractionated, and fractions were further processed by chromatographic procedures to yield five known dimeric acylphloroglucinol derivatives uliginosin A, uliginosin B, isouliginosin B, hyperbrasilol B and isohyperbrasilol B. In addition, two monomeric and two dimeric acylphloroglucinol structures were identified in H. andinum (roots extract) and H. laricifolium for the first time, andinin A, hyperlaricifolin A, laricifolin A and laricifolin B. Andinin A showed potential antidepressant-like activity in the forced swimming test. Similarly, the antidepressant-like activity of the crude ethanolic extracts was assessed. These four extracts possessed a potential antidepressant-like activity. The phytochemical analyses by TLC, HPLC-DAD and UPLCDAD/Q-TOF-MS revealed that the extracts were rich in flavonoids, principally hyperoside. The n-hexane extracts were also analyzed by a new HPLC-DAD fingerprint method associated with LC-MS and UPLC-Q-TOF-MS. The presence of M + 14 higher homologues and regioisomers could be distinguished. The natural occurrence of these five M + 14 higher homologues is described and the presence of other compounds identified by their MS fragmentation pattern is presented. These extracts and their main dimeric acylphloroglucinol component were able to potently inhibit the LPS-induced chemotaxis on rat PMN. These results suggest that extracts of Hypericum species from sections Brathys and Trigynobrathys are potential sources of new anti-inflammatory and antidepressant molecules

Smaller Gene Networks Permit Longer Persistence in Fast-Changing Environments

The environments in which organisms live and reproduce are rarely static, and as the environment changes, populations must evolve so that phenotypes match the challenges presented. The quantitative traits that map to environmental variables are underlain by hundreds or thousands of interacting genes whose allele frequencies and epistatic relationships must change appropriately for adaptation to occur. Extending an earlier model in which individuals possess an ecologically-critical trait encoded by gene networks of 16 to 256 genes and random or scale-free topology, I test the hypothesis that smaller, scale-free networks permit longer persistence times in a constantly-changing environment. Genetic architecture interacting with the rate of environmental change accounts for 78% of the variance in trait heritability and 66% of the variance in population persistence times. When the rate of environmental change is high, the relationship between network size and heritability is apparent, with smaller and scale-free networks conferring a distinct advantage for persistence time. However, when the rate of environmental change is very slow, the relationship between network size and heritability disappears and populations persist the duration of the simulations, without regard to genetic architecture. These results provide a link between genes and population dynamics that may be tested as the -omics and bioinformatics fields mature, and as we are able to determine the genetic basis of ecologically-relevant quantitative traits

Modelling the potential for prescribed burning to mitigate carbon emissions from wildfires in fire-prone forests of Australia

Prescribed fire can potentially reduce carbon emissions from unplanned fires. This potential will differ among ecosystems owing to inherent differences in the efficacy of prescribed burning in reducing unplanned fire activity (or 'leverage', i.e. the reduction in area of unplanned fire per unit area of prescribed fire). In temperate eucalypt forests, prescribed burning leverage is relatively low and potential for mitigation of carbon emissions from unplanned fires via prescribed fire is potentially limited. Simulations of fire regimes accounting for non-linear patterns of fuel dynamics for three fuel types characteristic of eucalypt forests in south-eastern Australia supported this prediction. Estimated mean annual fuel consumption increased with diminishing leverage and increasing rate of prescribed burning, even though average fire intensity (prescribed and unplanned fires combined) decreased. The results indicated that use of prescribed burning in these temperate forests is unlikely to yield a net reduction in carbon emissions. Future increases in burning rates under climate change may increase emissions and reduce carbon sequestration. A more detailed understanding of the efficacy of prescribed burning and dynamics of combustible biomass pools is required to clarify the potential for mitigation of carbon emissions in temperate eucalypt forests and other ecosystems