RESUMO
The impact of invasion by a single non-native species on the function and structure of ecological communities can be significant, and the effects can become more drastic-and harder to predict-when multiple species invade as a group. Here we modify a dynamic Boolean model of plant-pollinator community assembly to consider the invasion of native communities by multiple invasive species that are selected either randomly or such that the invaders constitute a stable community. We show that, compared to random invasion, whole community invasion leads to final stable communities (where the initial process of species turnover has given way to a static or near-static set of species in the community) including both native and non-native species that are larger, more likely to retain native species, and which experience smaller changes to the topological measures of nestedness and connectance. We consider the relationship between the prevalence of mutualistic interactions among native and invasive species in the final stable communities and demonstrate that mutualistic interactions may act as a buffer against significant disruptions to the native community.
Assuntos
Ecossistema , Espécies Introduzidas , Biota , Plantas , SimbioseRESUMO
Alginate-gelatin hydrogels mimicking extracellular matrix (ECM) of soft tissues have been generated by static-dynamic double crosslinking, allowing fine control over the physical and chemical properties. Dynamic crosslinking provides self-healing and injectability attributes to the hydrogel and promotes cell migration and proliferation, while the static network improves stability. The static crosslinking was performed by enzymatic coupling of the tyrosine residues of gelatin with tyramine residues inserted in the alginate backbone, catalyzed by horseradish peroxidase (HRP). The dynamic crosslinking was obtained by functionalizing alginate with 3-aminophenylboronic acid which generates a reversible bond with the vicinal hydroxyl groups of the alginate chains. Varying the ratio of alginate and gelatin, hydrogels with different properties were obtained, and the most suitable for 3D soft tissue model development with a 2.5:1 alginate:gelatin molar ratio was selected. The selected hydrogel was characterized with a swelling test, rheology test, self-healing test and by cytotoxicity, and the formulation resulted in transparent, reproducible, varying biomaterial batch, with a fast gelation time and cell biocompatibility. It is able to modulate the loss of the inner structure stability for a longer time with respect to the formulation made with only covalent enzymatic crosslinking, and shows self-healing properties.
Assuntos
Gelatina , Hidrogéis , Hidrogéis/química , Gelatina/química , Alginatos/química , Materiais Biocompatíveis/químicaRESUMO
Targeting of glucagon-like peptide 1 receptor (GLP-1R), expressed on the surface of pancreatic ß-cells, is of great interest for the development of advanced therapies for diabetes and diagnostics for insulinoma. We report the conjugation of exendin-4 (Ex-4), an approved drug to treat type 2 diabetes, to poly-γ-glutamic acid (γ-PGA) to obtain more stable and effective GLP-1R ligands. Exendin-4 modified at Lysine-27 with PEG4-maleimide was conjugated to γ-PGA functionalized with furan, in different molar ratios, exploiting a chemoselective Diels-Alder cycloaddition. The γ-PGA presenting the highest number of conjugated Ex-4 molecules (average 120 per polymeric chain) showed a double affinity towards GLP-1R with respect to exendin per se, paving the way to improved therapeutic and diagnostic applications.
Assuntos
Diabetes Mellitus Tipo 2 , Neoplasias Pancreáticas , Exenatida/química , Receptor do Peptídeo Semelhante ao Glucagon 1 , Ácido Glutâmico , Humanos , Peptídeos/química , Ácido Poliglutâmico/análogos & derivados , Compostos Radiofarmacêuticos/químicaRESUMO
In lung cancer, CD133+ cells represent the subset of cancer stem cells (CSC) able to sustain tumor growth and metastatic dissemination. CSC function is tightly regulated by specialized niches composed of both stromal cells and extracellular matrix (ECM) proteins, mainly represented by collagen. The relevance of collagen glycosylation, a fundamental post-translational modification controlling several biological processes, in regulating tumor cell phenotype remains, however, largely unexplored. To investigate the bioactive effects of differential ECM glycosylation on lung cancer cells, we prepared collagen films functionalized with glucose (Glc-collagen) and galactose (Gal-collagen) exploiting a neoglycosylation approach based on a reductive amination of maltose and lactose with the amino residues of collagen lysines. We demonstrate that culturing of tumor cells on collagen determines a glycosylation-dependent positive selection of CSC and triggers their expansion/generation. The functional relevance of CD133+ CSC increase was validated in vivo, proving an augmented tumorigenic and metastatic potential. High expression of integrin ß1 in its active form is associated with an increased proficiency of tumor cells to sense signaling from glycosylated matrices (glyco-collagen) and to acquire stemness features. Accordingly, inhibition of integrin ß1 in tumor cells prevents CSC enrichment, suggesting that binding of integrin ß1 to Glc-collagen subtends CSC expansion/generation. We provide evidence suggesting that collagen glycosylation could play an essential role in modulating the creation of a niche favorable for the generation and selection/survival of lung CSC. Interfering with this crosstalk may represent an innovative therapeutic strategy for lung cancer treatment.
Assuntos
Colágeno/metabolismo , Integrina beta1/metabolismo , Neoplasias Pulmonares/metabolismo , Células-Tronco Neoplásicas/metabolismo , Células A549 , Antígeno AC133/metabolismo , Animais , Linhagem Celular Tumoral , Matriz Extracelular/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Glicosilação , Humanos , Pulmão/metabolismo , Camundongos , Camundongos SCID , Transdução de Sinais/fisiologiaRESUMO
Cancer patients are characterized by hypercoagulable state and an increased rate of thrombotic events, the most common being venous thromboembolism. Several hemostatic pathways that are significantly implicated in mechanisms of thromboembolic disease are also involved in growth, invasion, and metastatic spread of malignant cells as well in tumor-induced neo-angiogenesis. This close connection between cancer and the hemostatic system has prompted numerous studies on the role of alterations in the level plasma biomarkers of the different compartments of hemostasis in predicting cancer prognosis. In this review, we collect the results of several exemplificative studies that have evaluated clotting activation biomarkers in relation to different cancer outcomes with a final emphasis on current research and forthcoming directions in this field.
Assuntos
Hemostáticos , Neoplasias , Biomarcadores , Coagulação Sanguínea , Hemostasia , HumanosRESUMO
In cancer patients, hypercoagulability is a common finding. It has been associated with an increased risk of venous thromboembolism, but also to tumor proliferation and progression. In this prospective study of a large cohort of breast cancer patients, we aimed to evaluate whether pre-chemotherapy abnormalities in hemostatic biomarkers levels: (i) are associated with breast cancer-specific clinico-pathological features; and (ii) can predict for disease recurrence. D-dimer, fibrinogen, prothrombin fragment 1+2, and FVIIa/antithrombin levels were measured in 701 early-stage resected breast cancer patients candidate to adjuvant chemotherapy and prospectively enrolled in the HYPERCAN study. Significant prognostic parameters for disease recurrence were identified by Cox regression multivariate analysis and used for generating a risk assessment model. Pre-chemotherapy D-dimer, fibrinogen, and pro-thrombin fragment 1+2 levels were significantly associated with tumor size and lymph node metastasis. After 3.4 years of follow up, 71 patients experienced a recurrence. Cox multivariate analysis identified prothrombin fragment 1+2, tumor size, and Luminal B HER2-negative or triple negative molecular subtypes as independent risk factors for disease recurrence. Based on these variables, we generated a risk assessment model that significantly differentiated patients at low- and high-risk of recurrence (cumulative incidence: 6.2 vs 20.7%; Hazard Ratio=3.5; P<0.001). Our prospective clinical and laboratory data from the HYPERCAN study were crucial for generating a scoring model for assessing risk of disease recurrence in resected breast cancer patients, candidate to systemic chemotherapy. This finding stimulates future investigations addressing the role of plasma prothrombin fragment 1+2 in the management of breast cancer patients to provide the rationale for new therapeutic strategies. (The HYPERCAN study is registered at clinicaltrials.gov identifier 02622815).
Assuntos
Neoplasias da Mama , Biomarcadores , Biomarcadores Tumorais , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/terapia , Humanos , Recidiva Local de Neoplasia , Prognóstico , Estudos ProspectivosRESUMO
Glycans play a central role in the development and homeostasis of the central nervous system (CNS), so changes in the glycosylation profile of the cell surface and extracellular matrix (ECM) components are evident in CNS disorders. Regenerative medicine-based strategies using biomaterial platforms are being increasingly used to target these diseases and to study the glyco-signature of the physiological and pathological conditions, particularly through the use of biomaterials able to recapitulate natural components and physical organization of the ECM. Collagen hydrogels have shown potential as a vehicle for the delivery of cells into the brain, and their therapeutic effect can be expanded by functionalizing them to address the glycosylation patterns altered with specific brain disorders. The goal of this study is to develop and optimize a glycan-functionalized tridimensional collagen-based hydrogel that will make contact with and modulate the differentiation of a primary neuronal culture. The developed system would provide more information on how a glyco-engineered material can influence the native glyco-signature profile during the process of cell differentiation by a differential modulation of glycan expression at the tissue level. To this purpose, collagen polymers underwent one step reductive amination with maltose (Glc(α1-4)α-Glc) and lactose (Gal(ß1-4)ß-Glc) so that the pyranosidic structure of the reducing sugar could be sacrificed (acting as a linker) and the α-Glc and ß-Gal residues exposed, respectively. The glycoconjugate biopolymers were used to formulate hydrogels that were chemically and biologically characterized, and the glyco-signature profile of a neuronal culture after hydrogel treatment was analyzed by lectin staining. The hydrogel conjugated with glucose limited the astrocytic proliferation for up to 2 weeks and promoted the increase in sialylation while decreasing fucosylation by 2-fold. These results indicate the differential influence of glycan residues present in the matrix on cellular sugar expression and thus have potential to enhance cell delivery systems in the central nervous system.
Assuntos
Matriz Extracelular , Hidrogéis , Colágeno , Neurônios , PolissacarídeosRESUMO
Synthetic 3D extracellular matrices (ECMs) find application in cell studies, regenerative medicine, and drug discovery. While cells cultured in a monolayer may exhibit unnatural behavior and develop very different phenotypes and genotypes than in vivo, great efforts in materials chemistry have been devoted to reproducing in vitro behavior in in vivo cell microenvironments. This requires fine-tuning the biochemical and structural actors in synthetic ECMs. This review will present the fundamentals of the ECM, cover the chemical and structural features of the scaffolds used to generate ECM mimics, discuss the nature of the signaling biomolecules required and exploited to generate bioresponsive cell microenvironments able to induce a specific cell fate, and highlight the synthetic strategies involved in creating functional 3D ECM mimics.
Assuntos
Matriz Extracelular , Alicerces Teciduais , Diferenciação Celular , Medicina Regenerativa , Células-TroncoRESUMO
Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a life-threatening immune-mediated thrombotic microangiopathy. Daily therapeutic plasma exchange (TPE) and the optimized use of rituximab have strikingly improved the outcome of this disease, however the rate of disease recurrence remains high. Specific predictors of relapse in patients in remission can be relevant for an optimal patient management. In this study, we aimed to identify predictive variables of disease relapse in a multicenter cohort of 74 out of 153 iTTP patients. They were tested at different time points during remission for the levels of ADAMTS-13 activity and autoantibody, and did not receive pre-emptive treatment for ADAMTS-13 activity deficiency during remission. The results showed that the association of ADAMTS13 activity ≤20% with a high anti-ADAMTS-13 titer at remission, and the time to response to first line treatment ≥13 days, were independent predictive factors of disease relapse. In addition, the use of rituximab in patients with exacerbation or refractoriness to TPE was significantly associated with reduced relapse rate. By Cox regression analysis, patients with ADAMTS-13 activity ≤20% plus anti-ADAMTS13 antibody titer ≥15 U/mL at remission had an increased risk of relapse (HR 1.98, CI 95% 1.087-3.614; P < .02). These findings may help to outline more personalized therapeutic strategies in order to provide faster and sustained responses to first-line iTTP treatment and prevent relapses in these patients.
Assuntos
Proteína ADAMTS13/sangue , Autoanticorpos/sangue , Púrpura Trombocitopênica Trombótica/terapia , Feminino , Humanos , Masculino , Púrpura Trombocitopênica Trombótica/patologia , RecidivaRESUMO
The regeneration of the nervous system is a challenging task. Currently, regenerative medicine approaches that exploit nature-inspired cues are being studied and hold great promise. The possibility to use protein-based matrices functionalized with small oligo- and monosaccharides is of interest since these can be finely tuned to better mimic the native environment. Collagen has been selected as a promising material that has the potential to be further tailored to incorporate carbohydrates in order to drive cell behavior towards neuroregeneration. Indeed, the grafting of carbohydrates to collagen 2D matrices is proved to enhance its biological significance. In the present study, collagen 2D matrices were grafted with different carbohydrate epitopes, and their potential to drive F-11 neuroblastoma cells towards neuronal differentiation was evaluated. Collagen functionalized with α-glucosides was able to differentiate neuroblastoma cells into functional neurons, while sialyl α-(2â6)-galactosides stimulated cell proliferation.
Assuntos
Colágeno/química , Colágeno/farmacologia , Neuroblastoma/patologia , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Glicosilação , Humanos , Neurônios/citologia , Neurônios/efeitos dos fármacos , Medicina RegenerativaRESUMO
Thrombosis is a major cause of morbidity and mortality in cancer patients. The pathogenesis of blood coagulation activation in oncological patients is complex and involves both clinical and biological factors. Abnormalities in one or more coagulation test are common in cancer patients, even without thrombotic manifestations, indicating an ongoing hypercoagulable condition. Moreover, venous thromboembolism (VTE) can be the first symptom of an occult malignancy in an otherwise healthy individual. The levels of laboratory markers of activation of blood coagulation parallel the development of malignancy, being the coagulant mechanisms important for both thrombogenesis and tumor progression. Besides general clinical risk factors for VTE, also disease-specific clinical factors, i.e., type and stage of the tumor, and anticancer therapies increase the thrombotic risk in these patients. Furthermore, biological factors, including the cancer cell-specific prothrombotic properties together with the host cell inflammatory response to the tumor, are relevant as well as unique players in the pathogenesis of the cancer-associated hypercoagulability. Cancer cells produce and release procoagulant and fibrinolytic proteins, inflammatory cytokines, and procoagulant microparticles. They also express adhesion molecules binding to the receptors of host vascular cells (i.e., endothelial cells, platelets, and leukocytes), thereby stimulating the prothrombotic properties of these normal cells, including the shed of cell-specific microparticles and neutrophil extracellular traps. Of interest, several genes responsible for the cellular neoplastic transformation drive the programs of hemostatic properties expressed by cancer tissues. A better understanding of such mechanisms will help the development of novel strategies to prevent and treat the Trousseau's syndrome (i.e., cancer-associated thrombosis).
Assuntos
Neoplasias/fisiopatologia , Trombose/fisiopatologia , Coagulação Sanguínea/fisiologia , Humanos , Neoplasias/complicações , Trombose/etiologiaRESUMO
Non-native plant species reliant on insect pollination must attract novel pollinators in their introduced habitat to reproduce. Indeed, pollination services provided by resident floral visitors may contribute to the spread of non-native species, which may then affect the pollination services received by native plants. To determine the mechanisms by which an invasive thistle attracts pollinators in its introduced range, and whether its presence changes the pollinator visitation to native plant species, we compared bee visitation to native plants in the presence or absence of the invader. We experimentally tested the effect of a thistle invasion into a native plant community. We found that the non-native thistle was the most attractive of the plant species to visiting bee species. However, there was no effect of experimental treatment (presence of thistle) on bee abundance or visitation rate (bees per unit floral area per sample) to native plant species. Across 68 bee and 6 plant species, we found a significant correlation between pollen protein content and bee abundance and visitation rate. Thistle pollen also had a similar protein:lipid ratio to legumes, which correlated with bumble bee visitation. The high protein content of the thistle pollen, as compared to four native asters, may allow it to attract pollinators in novel ecosystems, and potentially contribute to its success as an invader. At the same time, this high protein pollen may act as a novel resource to pollinators in the thistle's invaded range.
Assuntos
Ecossistema , Flores , Animais , Abelhas , Plantas , Pólen , PolinizaçãoRESUMO
We designed liposomes dually functionalized with ApoE-derived peptide (mApoE) and chlorotoxin (ClTx) to improve their blood-brain barrier (BBB) crossing. Our results demonstrated the synergistic activity of ClTx-mApoE in boosting doxorubicin-loaded liposomes across the BBB, keeping the anti-tumour activity of the drug loaded: mApoE acts promoting cellular uptake, while ClTx promotes exocytosis of liposomes.
Assuntos
Antibióticos Antineoplásicos/farmacocinética , Apolipoproteínas E/metabolismo , Barreira Hematoencefálica/metabolismo , Doxorrubicina/análogos & derivados , Lipossomos/metabolismo , Venenos de Escorpião/metabolismo , Animais , Antibióticos Antineoplásicos/administração & dosagem , Antibióticos Antineoplásicos/farmacologia , Apolipoproteínas E/química , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/metabolismo , Linhagem Celular Tumoral , Doxorrubicina/administração & dosagem , Doxorrubicina/farmacocinética , Doxorrubicina/farmacologia , Humanos , Lipossomos/química , Modelos Moleculares , Peptídeos/química , Peptídeos/metabolismo , Polietilenoglicóis/administração & dosagem , Polietilenoglicóis/farmacocinética , Polietilenoglicóis/farmacologia , Venenos de Escorpião/química , EscorpiõesRESUMO
The cell microenvironment plays a pivotal role in mediating cell adhesion, survival, and proliferation in physiological and pathological states. The relevance of extracellular matrix (ECM) proteins in cell fate control is an important issue to take into consideration for both tissue engineering and cell biology studies. The glycosylation of ECM proteins remains, however, largely unexplored. In order to investigate the physio-pathological effects of differential ECM glycosylation, the design of affordable chemoselective methods for ECM components glycosylation is desirable. We will describe a new chemoselective glycosylation approach exploitable in aqueous media and on non-protected substrates, allowing rapid access to glyco-functionalized biomaterials.
Assuntos
Materiais Biocompatíveis/metabolismo , Técnicas de Cultura de Células/métodos , Proteínas da Matriz Extracelular/metabolismo , Materiais Biocompatíveis/química , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular/efeitos dos fármacos , Colágeno/química , Colágeno/farmacologia , Glicosilação , HumanosRESUMO
We enrolled 62 consecutive patients with advanced stage cancers and venous thromboembolism (VTE), prospectively followed until 1 year. All patients received 6 month low-molecular-weight heparin (LMWH) therapy. We evaluated thrombin generation (TG) and D-dimer levels at different time points, to determine whether they were sensitive to LMWH and explore a possible association with VTE recurrence, bleeding, and overall survival. During LMWH, levels of TG and D-dimer significantly dropped. No VTE recurrences occurred, one patient had cancer-related intestinal hemorrhage. LMWH treatment was effective in controlling patient hypercoagulation. No VTE recurrences were detected. High D-dimer concentration was an independent predictor of poor survival.
Assuntos
Anticoagulantes/administração & dosagem , Coagulação Sanguínea/efeitos dos fármacos , Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , Heparina de Baixo Peso Molecular/administração & dosagem , Neoplasias/complicações , Trombina/metabolismo , Tromboembolia Venosa/tratamento farmacológico , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Estudos de Casos e Controles , Regulação para Baixo , Esquema de Medicação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/sangue , Neoplasias/patologia , Estudos Prospectivos , Fatores de Tempo , Resultado do Tratamento , Tromboembolia Venosa/sangue , Tromboembolia Venosa/diagnóstico , Tromboembolia Venosa/etiologiaRESUMO
Tissue engineering relies on the possibility to engineer cell microenvironments by means of bioactive materials, biochemical and physical stimuli in order to guide cell behaviour and to regenerate damaged tissue. Despite the relevance of glycan epitopes as signaling molecules, and the recent advances in glycomics, their use as biomolecular cues at the interface between materials and cells for the controlled stimulation of adhesion and differentiation processes for regenerative medicine applications is still limited. In this concept article we will briefly outline the basis and the impact on health and economics of regenerative medicine, together with the recent applications of the glycocode in tissue regeneration approaches.
Assuntos
Materiais Biocompatíveis/química , Glicômica/métodos , Polímeros/química , Medicina Regenerativa/métodos , Engenharia Tecidual/métodos , Adesão Celular , Técnicas de Cultura de Células , Proliferação de Células , Humanos , Propriedades de Superfície , Alicerces Teciduais/químicaRESUMO
PURPOSE OF REVIEW: To provide an updated overview of the complex coagulopathy associated with malignancy, together with the advances in our knowledge of the interactions of cancer with the hemostatic system. Also, to offer an update of the recent progresses in the risk assessment, prevention, and treatment of thrombohemorrhagic complications in cancer patients. RECENT FINDINGS: Mechanisms underlying the hemostatic derangement caused by cancer include many prothrombotic properties of tumor tissues. Of extreme interest are the most recent findings that the regulation of tumor cell hemostatic protein expression is driven by oncogenes, the tumor-derived tissue factor-positive microparticles are an important player in thrombosis, and the changes in the tumor microenvironment in the presence of tissue factor affect 'dormant' cells to shift to a malignant phenotype.On the clinical side, risk assessment models, based on clinical and biological risk factors, are becoming very attractive to identify categories of cancer patients at different thrombotic risk. Unsuspected pulmonary embolism, incidentally discovered, is also opening an intensive area of research. Finally, new updates of the guidelines to help clinicians in the management of venous thromboembolism in cancer patient have been recently released. SUMMARY: The coagulopathy of cancer is complex. Thrombotic and bleeding complications significantly contribute to morbidity and mortality in this disease. The accrued knowledge of the underlying mechanisms is helping establish more accurate and appropriate interventions for the management of the thrombotic risk in these patients.
Assuntos
Transtornos da Coagulação Sanguínea/etiologia , Neoplasias/complicações , Transtornos da Coagulação Sanguínea/prevenção & controle , Hemostasia , Humanos , Guias de Prática Clínica como Assunto , Medição de RiscoRESUMO
Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the covalent surface modification of collagen-based matrices with small carbohydrate epitopes has been scarcely investigated. We report thereby the development of an efficient procedure for the chemoselective neoglycosylation of collagen matrices (patches) via a thiol-ene approach, between alkene-derived monosaccharides and the thiol-functionalized material surface. Synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), Fourier transform-infrared (FT-IR), and enzyme-linked lectin assay (ELLA) confirmed the effectiveness of the collagen neoglycosylation. Preliminary biological evaluation in osteoarthritic models is reported. The proposed methodology can be extended to any thiolated surface for the development of smart biomaterials for innovative approaches in regenerative medicine.
Assuntos
Materiais Biocompatíveis/química , Carboidratos/química , Química Click , Colágeno/química , Compostos de Sulfidrila/química , Animais , Sequência de Carboidratos , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática , Glicosilação , Masculino , Estrutura Molecular , Osteoartrite/terapia , Espectroscopia Fotoeletrônica , Ratos , Ratos Wistar , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
This study evaluates the functional procoagulant features of plasma microparticle (MP) to explore the MP contribution to the hypercoagulable state of patients with essential thrombocythemia (ET). Platelet-free plasma samples were obtained from 73 ET patients (37 positive for the JAK2V617F mutation) and 72 control subjects. The calibrated automated thrombogram (CAT) was performed in plasma samples to determine thrombin generation of MP-associated tissue factor (TF) and procoagulant phospholipid (PPL) activity, and the STA Procoag PPL assay to measure MP-PPL activity only. Both thrombin generation and PPL procoagulant activities were found significantly elevated in ET patients compared to controls, and were associated to significantly higher levels of TF antigen and FVIIa/AT complex. Thrombin generation was significantly greater in JAK2-V617F positive compared to JAK2-V617F negative patients and normal subjects. Significant correlations were found between the PPL-assay and the different parameters of the CAT assay. No difference was seen between the thrombosis and no thrombosis group. Prospective studies are needed to test whether MP-associated thrombin generation and procoagulant activity may predict for thrombosis in these patients.
Assuntos
Coagulação Sanguínea , Micropartículas Derivadas de Células/metabolismo , Fosfolipídeos/metabolismo , Trombocitemia Essencial/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Fator VIIa/metabolismo , Feminino , Humanos , Janus Quinase 2/genética , Masculino , Pessoa de Meia-Idade , Mutação , Trombina/biossíntese , Trombocitemia Essencial/sangue , Trombocitemia Essencial/genética , Trombocitemia Essencial/terapia , Tromboplastina/metabolismo , Adulto JovemRESUMO
Planting floral resources is a common strategy for increasing the abundance and diversity of beneficial flower-visiting insects in human-modified systems. However, the context of the local area and surrounding landscape may affect the attractiveness of these floral resource provisioning plots. We compared the relative effects of local floral resources and surrounding urban land-use on the abundance of bees on flowering plants in common gardens in eastern Tennessee, USA. We planted four types of common garden plots at each of five different landscapes representing a variety of surrounding land use: 1) Urban Garden, 2) Forage Grassland, 3) Mixed Agriculture, 4) Forest, and 5) Organic Farm. Each common garden plot type had a fixed plant community representing one of three plant families (Asteraceae, Fabaceae, Lamiaceae) or a mix of all three, and all four common gardens were replicated at all the sites. We concurrently sampled bees in the garden plots and in a 50 m radius (local area) around the garden plots. We found that the size of the floral display (i.e. the visual display size of flowers) and diversity of flowers in the local area did not affect bee abundance or species richness in the garden plots. Although there was a significant positive association between developed land use in a 2 km radius and bee abundance in the gardens, the effect was small, and there was no relationship between land use and bee abundance or species richness in the local area. There were significant differences in the composition of the bee community between the local area and garden plots, but the largest determinants of bee community composition and species richness in the gardens were floral display size and variation in the garden plant species in bloom. This finding is promising for anyone wishing to promote pollinator populations by providing more floral resources.