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To address the remaining knowledge gap regarding the distribution of seagrasses in Ireland, this study aimed a) to create an updated seagrass (Zostera spp.) distribution map, and b) to evaluate the environmental quality to which seagrass meadows are exposed. To achieve the first objective, we (i) combined the available data on seagrass distribution published to date, and (ii) mapped additional meadows by implementing an integrated method based on species distribution models, satellite-derived images, and snorkelling-based surveys. We mapped 209 new seagrass meadows (14.98 km2), representing a 37.03 % increase over previously reported extents. Consequently, the total extent of Irish seagrass meadows is estimated to be at least 54.85 km2. To address the second objective, we assessed the level of anthropogenic pressure of seagrass meadows based on the index provided by the Water Framework Directive of the European Environment Agency. This study demonstrates that Irish meadows are primarily located in areas with 'HIGH' and 'GOOD' water status.
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Climate plays a crucial role in shaping species distribution and evolution over time. Dr Vrba's Resource-Use hypothesis posited that zones at the extremes of temperature and precipitation conditions should host a greater number of climate specialist species than other zones because of higher historical fragmentation. Here, we tested this hypothesis by examining climate-induced fragmentation over the past 5 million years. Our findings revealed that, as stated by Vrba, the number of climate specialist species increases with historical regional climate fragmentation, whereas climate generalist species richness decreases. This relationship is approximately 40% stronger than the correlation between current climate and species richness for climate specialist species and 77% stronger for generalist species. These evidences suggest that the effect of climate historical fragmentation is more significant than that of current climate conditions in explaining mammal biogeography. These results provide empirical support for the role of historical climate fragmentation and physiography in shaping the distribution and evolution of life on Earth.
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Biodiversidade , Mudança Climática , Mamíferos , Animais , Mamíferos/fisiologia , Clima , Distribuição Animal , Filogeografia , Evolução BiológicaRESUMO
A fundamental question in dinosaur evolution is how they adapted to long-term climatic shifts during the Mesozoic and when they developed environmentally independent, avian-style acclimatization, becoming endothermic.1,2 The ability of warm-blooded dinosaurs to flourish in harsher environments, including cold, high-latitude regions,3,4 raises intriguing questions about the origins of key innovations shared with modern birds,5,6 indicating that the development of homeothermy (keeping constant body temperature) and endothermy (generating body heat) played a crucial role in their ecological diversification.7 Despite substantial evidence across scientific disciplines (anatomy,8 reproduction,9 energetics,10 biomechanics,10 osteohistology,11 palaeobiogeography,12 geochemistry,13,14 and soft tissues15,16,17), a consensus on dinosaur thermophysiology remains elusive.1,12,15,17,18,19 Differential thermophysiological strategies among terrestrial tetrapods allow endotherms (birds and mammals) to expand their latitudinal range (from the tropics to polar regions), owing to their reduced reliance on environmental temperature.20 By contrast, most reptilian lineages (squamates, turtles, and crocodilians) and amphibians are predominantly constrained by temperature in regions closer to the tropics.21 Determining when this macroecological pattern emerged in the avian lineage relies heavily on identifying the origin of these key physiological traits. Combining fossils with macroevolutionary and palaeoclimatic models, we unveil distinct evolutionary pathways in the main dinosaur lineages: ornithischians and theropods diversified across broader climatic landscapes, trending toward cooler niches. An Early Jurassic shift to colder climates in Theropoda suggests an early adoption of endothermy. Conversely, sauropodomorphs exhibited prolonged climatic conservatism associated with higher thermal conditions, emphasizing temperature, rather than plant productivity, as the primary driver of this pattern, suggesting poikilothermy with a stronger dependence on higher temperatures in sauropods.
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Evolução Biológica , Aves , Dinossauros , Fósseis , Animais , Dinossauros/anatomia & histologia , Dinossauros/fisiologia , Aves/fisiologia , Aves/anatomia & histologia , Fósseis/anatomia & histologia , Regulação da Temperatura Corporal/fisiologia , AclimataçãoRESUMO
C4 photosynthesis is a key innovation in land plant evolution, but its immediate effects on population demography are unclear. We explore the early impact of the C4 trait on the trajectories of C4 and non-C4 populations of the grass Alloteropsis semialata. We combine niche models projected into paleoclimate layers for the last 5 million years with demographic models based on genomic data. The initial split between C4 and non-C4 populations was followed by a larger expansion of the ancestral C4 population, and further diversification led to the unparalleled expansion of descendant C4 populations. Overall, C4 populations spread over three continents and achieved the highest population growth, in agreement with a broader climatic niche that rendered a large potential range over time. The C4 populations that remained in the region of origin, however, experienced lower population growth, rather consistent with local geographic constraints. Moreover, the posterior transfer of some C4-related characters to non-C4 counterparts might have facilitated the recent expansion of non-C4 populations in the region of origin. Altogether, our findings support that C4 photosynthesis provided an immediate demographic advantage to A. semialata populations, but its effect might be masked by geographic contingencies.
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Fotossíntese , Poaceae , Poaceae/genética , Fenótipo , DemografiaRESUMO
Mammal diversity affects carbon concentration in Amazonian soils. It is known that some species traits determine carbon accumulation in organisms (e.g., size and longevity), and are also related to feeding strategies, thus linking species traits to the type of organic remains that are incorporated into the soil. Trait diversity in mammal assemblages - that is, its functional diversity - may therefore constitute another mechanism linking biodiversity to soil organic matter (SOM) accumulation. To address this hypothesis, we analyzed across 83 mammal assemblages in the Amazon biome (Guyana), the elemental (by ED-XRF and CNH analysis) and molecular (FTIR-ATR) composition of SOM of topsoils (401 samples) and trait diversity (functional richness, evenness, and divergence) for each mammal assemblage. Lower mammal functional richness but higher functional divergence were related to higher content of carbonyl and aliphatic SOM, potentially affecting SOM recalcitrance. Our results might allow the design of biodiversity management plans that consider the effect of mammal traits on carbon sequestration and accumulation in soils.
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Diversity of plants and animals influence soil carbon through their contributions to soil organic matter (SOM). However, we do not know whether mammal and tree communities affect SOM composition in the same manner. This question is relevant because not all forms of carbon are equally resistant to mineralization by microbes and thus, relevant to carbon storage. We analyzed the elemental and molecular composition of 401 soil samples, with relation to the species richness of 83 mammal and tree communities at a landscape scale across 4.8 million hectares in the northern Amazon. We found opposite effects of mammal and tree richness over SOM composition. Mammal diversity is related to SOM rich in nitrogen, sulfur and iron whereas tree diversity is related to SOM rich in aliphatic and carbonyl compounds. These results help us to better understand the role of biodiversity in the carbon cycle and its implications for climate change mitigation.
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Past responses to environmental change provide vital baseline data for estimating the potential resilience of extant taxa to future change. Here, we investigate the latitudinal range contraction that terrestrial and freshwater turtles (Testudinata) experienced from the Late Cretaceous to the Paleogene (100.5-23.03 mya) in response to major climatic changes. We apply ecological niche modeling (ENM) to reconstruct turtle niches, using ancient and modern distribution data, paleogeographic reconstructions, and the HadCM3L climate model to quantify their range shifts in the Cretaceous and late Eocene. We then use the insights provided by these models to infer their probable ecological responses to future climate scenarios at different representative concentration pathways (RCPs 4.5 and 8.5 for 2100), which project globally increased temperatures and spreading arid biomes at lower to mid-latitudes. We show that turtle ranges are predicted to expand poleward in the Northern Hemisphere, with decreased habitat suitability at lower latitudes, inverting a trend of latitudinal range contraction that has been prevalent since the Eocene. Trionychids and freshwater turtles can more easily track their niches than Testudinidae and other terrestrial groups. However, habitat destruction and fragmentation at higher latitudes will probably reduce the capability of turtles and tortoises to cope with future climate changes.
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Tartarugas , Animais , Tartarugas/fisiologia , Mudança Climática , Ecossistema , Água Doce , ProbabilidadeRESUMO
BACKGROUND: Meatal advancement with glanduloplasty (MAGPI) has been in the recent years one of the most frequently surgical techniques used for the correction of distal hypospadias. Multiple modifications have been described to improve the results ofthis technique. In 2004 we presented the initial results of the New Modern MAGPI or DUAGPI (distal urethral advancement and glanduloplasty) as a surgical alternative to the original MAGPI. OBJETIVE: The objective of the present study is to evaluate the applicability, safety and the cosmetic results obtained with this technique, as well as the long-term complications. MATERIALS AND METHODS: Retrospective and descriptive study of patients with distal hypospadias, corrected using the DUAPI technique, between 2002 and 2018. SURGICAL TECHNIQUE: Initially, an artificial erection was performed, the absence of curvature in all patients is proven. A skin denudation was performed up to the base of the penis in those children with a bend greater than 30. Second, the distal urethral disconnection was performed at the posterior and lateral urethral level. A glandular triangular section is made to accommodate the distal urethra and to allow a conical appearance with a final glandular. Finally, the fixation of the distal urethral to the glandular tip and the anterior glandular closure is performed. We performed an annual follow-up of all patients. The analysis of all the variables collected during surgery and follow-up was done with SPSS 22 statistical package. RESULTS: 90 patients meet inclusion criteria and were included in the study (32 glandular and 58 coronal). The mean surgical time was 47 minutes (Range: 37-71 minutes). The mean follow-up was 9.4 years (2.1-15 years). 2 patients had meatal stenosis after surgery, 4 mild glandular retraction, and 2 urethrocutaneous fistula. Six of the 8 patients with a complication were successfully reoperated. 92% of the patients and their families were satisfied with the cosmetic result obtained after surgery (83 patients). CONCLUSION: DUAGPI technique is simple, reproducible and optimal for most distal hypospadias. It is a safe technique, with a low complication rate. The final aesthetic result is satisfactory in most cases, with a conical glans and a natural cosmetic appearance.
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Hipospadia , Criança , Seguimentos , Humanos , Hipospadia/cirurgia , Lactente , Masculino , Pênis/cirurgia , Estudos Retrospectivos , Resultado do Tratamento , Uretra/cirurgia , Procedimentos Cirúrgicos Urológicos Masculinos/métodosRESUMO
The resource-use hypothesis, proposed by E.S. Vrba, states that habitat fragmentation caused by climatic oscillations would affect particularly biome specialists (species inhabiting only one biome), which might show higher speciation and extinction rates than biome generalists. If true, lineages would accumulate biome-specialist species. This effect would be particularly exacerbated for biomes located at the periphery of the global climatic conditions, namely, biomes that have high/low precipitation and high/low temperature such as rainforest (warm-humid), desert (warm-dry), steppe (cold-dry) and tundra (cold-humid). Here, we test these hypotheses in swallowtail butterflies, a clade with more than 570 species, covering all the continents but Antarctica, and all climatic conditions. Swallowtail butterflies are among the most studied insects, and they are a model group for evolutionary biology and ecology studies. Continental macroecological rules are normally tested using vertebrates, this means that there are fewer examples exploring terrestrial invertebrate patterns at global scale. Here, we compiled a large Geographic Information System database on swallowtail butterflies' distribution maps and used the most complete time-calibrated phylogeny to quantify diversification rates (DRs). In this paper, we aim to answer the following questions: (1) Are there more biome-specialist swallowtail butterflies than biome generalists? (2) Is DR related to biome specialization? (3) If so, do swallowtail butterflies inhabiting extreme biomes show higher DRs? (4) What is the effect of species distribution area? Our results showed that swallowtail family presents a great number of biome specialists which showed substantially higher DRs compared to generalists. We also found that biome specialists are unevenly distributed across biomes. Overall, our results are consistent with the resource-use hypothesis, species climatic niche and biome fragmentation as key factors promoting isolation.
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Borboletas , Animais , Regiões Antárticas , Evolução Biológica , Borboletas/genética , Ecossistema , FilogeniaRESUMO
Investigation of ecological responses of species to past climate oscillations provides crucial information to understand the effects of global warming. In this work, we investigated how past climate changes affected the distribution of six bird species with different climatic requirements and migratory behaviours in the Western Palearctic and in Africa. Species Distribution Models and Marine Isotopic Stage (MIS) 2 fossil occurrences of selected species were employed to evaluate the relation between changes in range size and species climatic tolerances. The Last Glacial Maximum (LGM) range predictions, generally well supported by the MIS 2 fossil occurrences, suggest that cold-dwelling species considerably expanded their distribution in the LGM, experiencing more pronounced net changes in range size compared to temperate species. Overall, the thermal niche proves to be a key ecological trait for explaining the impact of climate change in species distributions. Thermal niche is linked to range size variations due to climatic oscillations, with cold-adapted species currently suffering a more striking range reduction compared to temperate species. This work also supports the persistence of Afro-Palearctic migrations during the LGM due to the presence of climatically suitable wintering areas in Africa even during glacial maxima.
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Mudança Climática , Ecossistema , África , Animais , Aves , FilogeografiaRESUMO
Dinosaurs dominated Mesozoic terrestrial ecosystems globally. However, whereas a pole-to-pole geographic distribution characterized ornithischians and theropods, sauropods were restricted to lower latitudes. Here, we evaluate the role of climate in shaping these biogeographic patterns through the Jurassic-Cretaceous (201-66 mya), combining dinosaur fossil occurrences, past climate data from Earth System models, and habitat suitability modeling. Results show that, uniquely among dinosaurs, sauropods occupied climatic niches characterized by high temperatures and strongly bounded by minimum cold temperatures. This constrained the distribution and dispersal pathways of sauropods to tropical areas, excluding them from latitudinal extremes, especially in the Northern Hemisphere. The greater availability of suitable habitat in the southern continents, particularly in the Late Cretaceous, might be key to explaining the high diversity of sauropods there, relative to northern landmasses. Given that ornithischians and theropods show a flattened or bimodal latitudinal biodiversity gradient, with peaks at higher latitudes, the closer correspondence of sauropods to a subtropical concentration could hint at fundamental thermophysiological differences to the other two clades.
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Dinossauros , Animais , Biodiversidade , Dinossauros/anatomia & histologia , Ecossistema , Fósseis , FilogeniaRESUMO
Asian cobras (genus Naja) are venomous snakes distributed from the Middle East to Southeast Asia. Because cobras often live near humans settlements, they are responsible for a large part of snakebite incidents and as such pose a challenge for public health systems. In the light of growing human populations, correctly mapping the present and future ranges of Asian cobras is therefore important for both biological conservation and public health management. Here, we mapped the potential climatic niches of ten Asian cobra species for both the present and the future, with the aim to quantify changes in climate and human population densities relative to their current and future ranges. Our analyses reveal that cobras that are adapted to dry climates and inhabit islands have narrow climatic niches, while those of mainland species with larger geographic ranges are much wider. We also found a higher degree of fragmentation of future cobra distributions; within the next 50 years, Asian cobras will lose an average of around 60% of their current suitable climatic range. In the near future, Naja mandalayensis, N. sputatrix, N. samarensis, and N. philippinensis are likely to have no accessible suitable climate space left. Besides, a further increase of human populations in this region may also exponentially accelerate the effects of anthropogenic impacts. Solutions for conservation may involve awareness and appropriate use of law to overcome the rate of habitat degradation and the increase of animal trade of Asian cobras, while promoting investment on health systems to avoid snakebite fatalities.
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Biodiversidade , Mudança Climática , Ecossistema , Elapidae , Atividades Humanas , Densidade Demográfica , Animais , Ásia , Conservação dos Recursos Naturais , Geografia , Humanos , Estações do Ano , TemperaturaRESUMO
Prognosis for relapsed or refractory (R/R) acute myeloid leukemia (AML) despite salvage therapy is dismal. This phase I dose-escalation trial assessed the safety and preliminary clinical activity of selinexor, an oral exportin-1 (XPO1) inhibitor, in combination with FLAG-Ida in younger R/R AML patients. The aim was to find the recommended phase 2 dose (RP2D) and maximum tolerated dose (MTD). Fourteen patients were included, and selinexor dosage was 60 mg (3 patients), 80 mg (3 patients), and 100 mg (7 patients) weekly. No dose-limiting toxicities were reported. Grade ≥3 non-hematologic adverse events (AEs) occurred in 78.6% of patients. Two patients were non MTD evaluable due to early death, and overall, 3 out of 14 patients (21.4%) had fatal AEs. Five out of 12 (42%) response and MTD evaluable patients achieved a complete remission (CR; n=4) or CR with incomplete hematologic recovery (CRi, n=1), and 4 patients (33%) subsequently underwent allogeneic transplantation. The median overall survival (OS) and event-free survival (EFS) were 6.0 (range 0.9-19.3) and 1.1 months (range 0.7-19.3), respectively. Using selinexor 100 mg/weekly, CR/CRi rate of 66.7%, OS 13.6 months (range, 1.6-19.3), and EFS 10.6 months (range, 0.9-19.3). At last follow-up, 3 patients were alive. Selinexor 100 mg/weekly with FLAG-Ida combination in R/R AML showed acceptable tolerability and efficacy, establishing the RP2D of this regimen in future clinical trials. ClinicalTrials.gov Identifier: NCT03661515.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Hidrazinas/uso terapêutico , Leucemia Mieloide Aguda/tratamento farmacológico , Recidiva Local de Neoplasia/tratamento farmacológico , Triazóis/uso terapêutico , Vidarabina/análogos & derivados , Adulto , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Citarabina/administração & dosagem , Citarabina/efeitos adversos , Citarabina/uso terapêutico , Fator Estimulador de Colônias de Granulócitos/administração & dosagem , Fator Estimulador de Colônias de Granulócitos/efeitos adversos , Fator Estimulador de Colônias de Granulócitos/uso terapêutico , Humanos , Hidrazinas/administração & dosagem , Hidrazinas/efeitos adversos , Idarubicina/administração & dosagem , Idarubicina/efeitos adversos , Idarubicina/uso terapêutico , Masculino , Dose Máxima Tolerável , Pessoa de Meia-Idade , Resultado do Tratamento , Triazóis/administração & dosagem , Triazóis/efeitos adversos , Vidarabina/administração & dosagem , Vidarabina/efeitos adversos , Vidarabina/uso terapêuticoAssuntos
Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Niacinamida/análogos & derivados , Inibidores de Proteínas Quinases/uso terapêutico , Pirazóis/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Proteínas de Fusão bcr-abl/antagonistas & inibidores , Humanos , Masculino , Pessoa de Meia-Idade , Niacinamida/efeitos adversos , Niacinamida/uso terapêutico , Inibidores de Proteínas Quinases/efeitos adversos , Pirazóis/efeitos adversos , Resultado do Tratamento , Adulto JovemRESUMO
RESUMEN Introducción: La insuficiencia cervical se concibe hoy día como un proceso biológico continuo con grados progresivos de insuficiencia. La expresión más extrema de la insuficiencia cervical se conoce como "bolsa en reloj de arena". La mayoría de los autores están de acuerdo en recomendar el reposo en cama y realizar cerclaje cervical de emergencia. Objetivo: Presentar el caso de una gestante en la que se logró la reversión del prolapso de las membranas amnióticas en "reloj de arena" con buenos resultados perinatales. Presentación de caso: Paciente de 31 años con antecedentes de parto anterior a las 36,5 semanas, que en los momentos actuales cursa una gestación de 20,6 semanas. Acude a la consulta por dolor en hipogastrio y al examen físico se comprueba que la bolsa amniótica protruye por el orificio cervical externo y presenta una dilatación cervical de 2 cm. Se aplica tratamiento medicamentoso y se reduce el prolapso de la bolsa. Conclusiones: Con el tratamiento conservador se logró una buena evolución de la gestación, con parto eutócico y buenos resultados perinatales(AU)
ABSTRACT Introduction: Cervical insufficiency is conceived today as a continuous biological process with progressive degrees of insufficiency. The most extreme expression of cervical insufficiency is known as "hourglass bag". Most authors agree to recommend bed rest and perform emergency cervical cerclage. Objective: To report the case of a pregnant woman in whom the prolapse reversal of the amniotic membranes in hourglass was achieved with good perinatal results. Case report: A 31-year-old patient who is currently pregnant at 20.6 weeks and has history of childbirth prior to 36.5 weeks. She comes to the consultation complaining of pain in hypogastrium. The physical examination shows that the amniotic sac protrudes through the external cervical orifice and there is 2cm cervical dilation. Drug treatment is applied and the prolapse of the sac is reduced. Conclusions: The conservative treatment achieved good evolution of the gestation, with eutócico childbirth and good perinatal results(AU)
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Humanos , Feminino , Adulto , Dor/etiologia , Prolapso , Cerclagem Cervical/métodos , Tratamento Conservador/métodos , Exame Físico/efeitos adversos , Repouso em Cama/métodosRESUMO
Ovarian cancer is the second most common malignant neoplasm of the genital tract. Staging procedures for ovarian cancer include longitudinal laparotomy, hysterectomy, bilateral salpingo-oophorectomy and infragastric omentectomy as well as systematic pelvic and para-aortic lymphadenectomy. In general, the goal of this primary procedure is to achieve the maximum cytoreduction of all abdominal diseases; a residual disease <1 cm defines optimal cytoreduction, however, a maximal effort should be made to remove all gross disease as this offers superior survival outcomes. The role of lymphadenectomy in ovarian cancer has been the focus of gynecological oncologists during recent years. The core issue of the controversy is whether the removal of lymph nodes should be performed only to stage the disease or if the removal itself improves survival. To further comprehend the issue, one must take into account that several studies have shown that systematic lymphadenectomy is associated with a risk of vascular injury, lymph cyst formation, pulmonary embolism and increased post-operative mortality even when performed by surgeons with extensive experience. We present an extensive review of the available literature on the matter, hoping to provide some insight into the true need for such a procedure.
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Excisão de Linfonodo/métodos , Neoplasias Ovarianas/cirurgia , Complicações Pós-Operatórias/etiologia , Espaço Retroperitoneal/cirurgia , Feminino , Humanos , Excisão de Linfonodo/efeitos adversos , Linfonodos/cirurgia , Metástase Linfática , Neoplasias Ovarianas/patologia , Complicações Pós-Operatórias/epidemiologiaRESUMO
Also known as inflammatory pseudotumor, inflammatory myofibroblastic tumor is now considered a true low-grade neoplasm. Although the lung is the most common site, it has been described in many other locations, including the breast; the first report of breast involvement was by Pettinato et al. in 1988. We report the case of a 52-year-old perimenopausal woman presenting with a slow-growing mass in her right breast. Mammography revealed a well demarcated lesion which was hypoechoic on ultrasound. A needle biopsy was performed yielding an initial diagnosis of myofibroma and the mass was resected. Histopathology of the 5-cm tumor revealed a fusocellular proliferation with a striking presence of inflammatory cells, morphologically and immunohistochemically concordant with inflammatory myofibroblastic tumor. The patient underwent further surgery to ensure free margins and after a negative extension study (PET-CT) is receiving no further therapy. To date, she has shown no signs of recurrence 8 months postoperatively. Inflammatory myofibroblastic tumor of the breast is very infrequent, with less than 30 reported cases. Differential diagnosis with both benign and malignant entities is extensive and it may precede or coexist with carcinoma of the adjacent breast. Although it is considered a low-malignant potential lesion, there are well documented cases of recurrence and even metastasis. Surgical resection with wide margins is the primary treatment and no systemic therapy is indicated; however, clinical follow-up is mandatory as there are no well-established criteria as yet to predict the biological behavior of this tumor.
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Neoplasias da Mama/patologia , Granuloma de Células Plasmáticas/patologia , Feminino , Humanos , Pessoa de Meia-Idade , Doenças RarasRESUMO
Recently, the European Commission adopted a new strategy to halt the loss of biodiversity. Member states are expected to favor a more effective collection and redistribution of European Union (EU) funds under the current Multiannual Financial Framework for 2014-2020. Because of the large spatial variation in the distribution of biodiversity and conservation needs at the continental scale, EU instruments should ensure that countries with higher biodiversity values get more funds and resources for the conservation than other countries. Using linear regressions, we assessed the association between conservation investments and biodiversity values across member states, accounting for a variety of conservation investment indicators, taxonomic groups (including groups of plants, vertebrates, and invertebrates), and indicators of biodiversity value. In general, we found clear overall associations between conservation investments and biodiversity variables. However, some countries received more or less investment than would be expected based on biodiversity values in those countries. We also found that the extensive use of birds as unique indicators of conservation effectiveness may lead to biased decisions. Our results can inform future decisions regarding funding allocation and thus improve distribution of EU conservation funds.
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Biodiversidade , Conservação dos Recursos Naturais , Animais , Aves , União Europeia , Investimentos em SaúdeRESUMO
Eight years of excavation work by the Olduvai Geochronology and Archaeology Project (OGAP) has produced a rich vertebrate fauna from several sites within Bed II, Olduvai Gorge, Tanzania. Study of these as well as recently re-organized collections from Mary Leakey's 1972 HWK EE excavations here provides a synthetic view of the faunal community of Olduvai during Middle Bed II at â¼1.7-1.4 Ma, an interval that captures the local transition from Oldowan to Acheulean technology. We expand the faunal list for this interval, name a new bovid species, clarify the evolution of several mammalian lineages, and record new local first and last appearances. Compositions of the fish and large mammal assemblages support previous indications for the dominance of open and seasonal grassland habitats at the margins of an alkaline lake. Fish diversity is low and dominated by cichlids, which indicates strongly saline conditions. The taphonomy of the fish assemblages supports reconstructions of fluctuating lake levels with mass die-offs in evaporating pools. The mammals are dominated by grazing bovids and equids. Habitats remained consistently dry and open throughout the entire Bed II sequence, with no major turnover or paleoecological changes taking place. Rather, wooded and wet habitats had already given way to drier and more open habitats by the top of Bed I, at 1.85-1.80 Ma. This ecological change is close to the age of the Oldowan-Acheulean transition in Kenya and Ethiopia, but precedes the local transition in Middle Bed II. The Middle Bed II large mammal community is much richer in species and includes a much larger number of large-bodied species (>300 kg) than the modern Serengeti. This reflects the severity of Pleistocene extinctions on African large mammals, with the loss of large species fitting a pattern typical of defaunation or 'downsizing' by human disturbance. However, trophic network (food web) analyses show that the Middle Bed II community was robust, and comparisons with the Serengeti community indicate that the fundamental structure of food webs remained intact despite Pleistocene extinctions. The presence of a generalized meat-eating hominin in the Middle Bed II community would have increased competition among carnivores and vulnerability among herbivores, but the high generality and interconnectedness of the Middle Bed II food web suggests this community was buffered against extinctions caused by trophic interactions.