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2.
Oncologist ; 25(12): e1956-e1967, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32762143

RESUMEN

BACKGROUND: Adjuvant chemotherapy with 5-fluorouracil (5-FU) and oxaliplatin increases recurrence-free and overall survival in patients with colon adenocarcinoma. It is known that these drugs have been associated with cardio- and neurotoxicity. We investigated the effects of 5-FU ± oxaliplatin on cardiac function, vascular responses, neurovascular control, and physical capacity in patients with colon cancer. METHODS: Twenty-nine patients with prior colectomy for stage II-III adenocarcinoma and clinical indication for adjuvant chemotherapy were allocated to receive 5-FU (n = 12) or 5-FU + oxaliplatin (n = 17), according to the oncologist's decision. All the analyses were performed just before and after the end of chemotherapy. Cardiac function was assessed by echocardiography and speckle tracking, and cardiac autonomic control was assessed by heart rate variability (HRV). Vascular endothelial function was assessed by flow-mediated dilation (FMD). Muscle sympathetic nerve activity (MSNA) was directly recorded by microneurography technique, and muscle blood flow by venous occlusion plethysmography. Physical capacity was evaluated by cardiopulmonary exercise test. RESULTS: Chemotherapy (pooled data) did not significantly change left ventricular ejection fraction (58 ± 1 vs. 55 ± 2%, p = .14), longitudinal strain (-18 ± 1 vs. -18 ± 1%, p = .66), and HRV. Likewise, chemotherapy did not significantly change FMD, muscle blood flow, and MSNA (33 ± 2 vs. 32 ± 1 bursts/min, p = .31). Physical capacity was not significantly changed in both groups. Similar findings were observed when the patients were subdivided in 5-FU and 5-FU + oxaliplatin treatment groups. 5-FU and 5-FU + oxaliplatin did not significantly change cardiac function, HRV, vascular responses, MSNA, and physical capacity. CONCLUSION: This study provides evidence that adjuvant treatment with 5-FU ± oxaliplatin is well tolerated and does not promote changes compatible with long-term cardiotoxicity. IMPLICATIONS FOR PRACTICE: Adjuvant chemotherapy with 5-fluorouracil (5-FU) and oxaliplatin increases recurrence-free and overall survival in patients with colon adenocarcinoma; however, these drugs have been associated with cardio- and neurotoxicity. This study investigated the effects of these drugs on cardiac function, vascular responses, neurovascular control, and physical capacity in patients with colon cancer. It was found that 5-FU and oxaliplatin did not significantly change cardiac function, cardiac autonomic control, vascular endothelial function, muscle sympathetic nerve activity, and physical capacity. This study provides evidence that adjuvant treatment with 5-FU ± oxaliplatin is well tolerated and does not promote changes compatible with long-term cardiotoxicity.


Asunto(s)
Neoplasias del Colon , Fluorouracilo , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Quimioterapia Adyuvante , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/patología , Fluorouracilo/uso terapéutico , Humanos , Leucovorina/uso terapéutico , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Compuestos Organoplatinos/uso terapéutico , Oxaliplatino/uso terapéutico , Volumen Sistólico , Función Ventricular Izquierda
4.
Bernardete, Weber; Bersch, Ferreira  C; Torreglosa, Camila R; Marcadenti, Aline; Lara, Enilda S; Silva, Jaqueline T da; Costa, Rosana P; Santos, Renato H N; Berwanger, Otavio; Bosquetti, Rosa; Pagano, Raira; Mota, Luis G S; Oliveira, Juliana D de; Soares, Rafael M; Galante, Andrea P; Silva, Suzana A da; Zampieri, Fernando G; Kovacs, Cristiane; Amparo, Fernanda C; Moreira, Priscila; Silva, Renata A da; Santos, Karina G dos; Monteiro, Aline S5,; Paiva, Catharina C J; Magnoni, Carlos D; Moreira, Annie S; Peçanha, Daniela O; Missias, Karina C S; Paula, Lais S de; Marotto, Deborah; Souza, Paula; Martins, Patricia R T; Santos, Elisa M dos; Santos, Michelle R; Silva, Luisa P; Torres, Rosileide S; Barbosa, Socorro N A A; Pinho, Priscila M de; Araujo, Suzi H A de; Veríssimo, Adriana O L; Guterres, Aldair S; Cardoso, Andrea F R; Palmeira, Moacyr M; Ataíde, Bruno R B de; Costa, Lilian P S; Marinho, Helyde A; Araújo, Celme B P de; Carvalho, Helen M S; Maquiné, Rebecca O; Caiado, Alessandra C; Matos, Cristina H de; Barretta, Claiza; Specht, Clarice M; Onofrei, Mihaela; Bertacco, Renata T A; Borges, Lucia R; Bertoldi, Eduardo G; Longo, Aline; Ribas, Bruna L P; Dobke, Fernanda; Pretto, Alessandra D B; Bachettini, Nathalia P; Gastaud, Alexandre; Necchi, Rodrigo; Souza, Gabriela C; Zuchinali, Priccila; Fracasso, Bianca M; Bobadra, Sara; Sangali, Tamirys D; Salamoni, Joyce; Garlini, Luíza M; Shirmann, Gabriela S; Los Santos, Mônica L P de; Bortonili, Vera M S; Santos, Cristiano P dos; Bragança, Guilherme C M; Ambrózio, Cíntia L; Lima, Susi B E; Schiavini, Jéssica; Napparo, Alechandra S; Boemo, Jorge L; Nagano, Francisca E Z; Modanese, Paulo V G; Cunha, Natalia M; Frehner, Caroline; Silva, Lannay F da; Formentini, Franciane S; Ramos, Maria E M; Ramos, Salvador S; Lucas, Marilia C S; Machado, Bruna G; Ruschel, Karen B; Beiersdorf, Jâneffer R; Nunes, Cristine E; Rech, Rafael L; Damiani, Mônica; Berbigier, Marina; Poloni, Soraia; Vian, Izabele; Russo, Diana S; Rodrigues, Juliane; Moraes, Maria A P de; Costa, Laura M da; Boklis, Mirena; El Kik, Raquel M; Adorne, Elaine F; Teixeira, Joise M; Trescastro, Eduardo P; Chiesa, Fernanda L; Telles, Cristina T; Pellegrini, Livia A; Reis, Lucas F; Cardoso, Roberta G M; Closs, Vera E; Feres, Noel H; Silva, Nilma F da; Silva, Neyla E; Dutra, Eliane S; Ito, Marina K; Lima, Mariana E P; Carvalho, Ana P P F; Taboada, Maria I S; Machado, Malaine M A; David, Marta M; Júnior, Délcio G S; Dourado, Camila; Fagundes, Vanessa C F O; Uehara, Rose M; Sasso, Sandramara; Vieira, Jaqueline S O; Oliveira, Bianca A S de; Pereira, Juliana L; Rodrigues, Isa G; Pinho, Claudia P S; Sousa, Antonio C S; Almeida, Andreza S; Jesus, Monique T de; Silva, Glauber B da; Alves, Lucicna V S; Nascimento, Viviane O G; Vieira, Sabrina A; Coura, Amanda G L; Dantas, Clenise F; Leda, Neuma M F S; Medeiros, Auriene L; Andrade, Ana C L; Pinheiro, Josilene M F; Lima, Luana R M de; Sabino, L S; Souza, C V S de; Vasconcelos, S M L; Costa, F A; Ferreira, R C; Cardoso, I B; Navarro, L N P; Ferreira, R B; Júnior, A E S; Silva, M B G; Almeida, K M M; Penafort, A M; Queirós, A P O de; Farias, G M N; Carlos, D M O; Cordeiro, C G N C; Vasconcelos, V B; Araújo, E M V M C de; Sahade, V; Ribeiro, C S A; Araujo, G A; Gonçalves, L B; Teixeira, C S; Silva, L M A J; Costa, L B de; Souza, T S; Jesus, S O de; Luna, A B; Rocha, B R S da; Santos, M A; Neto, J A F; Dias, L P P; Cantanhede, R C A; Morais, J M; Duarte, R C L; Barbosa, E C B; Barbosa, J M A; Sousa, R M L de; Santos, A F dos; Teixeira, A F; Moriguchi, E H; Bruscato, N M; Kesties, J; Vivian, L; Carli, W de; Shumacher, M; Izar, M C O; Asoo, M T; Kato, J T; Martins, C M; Machado, V A; Bittencourt, C R O; Freitas, T T de; Sant'Anna, V A R; Lopes, J D; Fischer, S C P M; Pinto, S L; Silva, K C; Gratão, L H A; Holzbach, L C; Backes, L M; Rodrigues, M P; Deucher, K L A L; Cantarelli, M; Bertoni, V M; Rampazzo, D; Bressan, J; Hermsdorff, H H M; Caldas, A P S; Felício, M B; Honório, C R; Silva, A da; Souza, S R; Rodrigues, P A; Meneses, T M X de; Kumbier, M C C; Barreto, A L; Cavalcanti, A B.
Am. heart j ; 215: 187-197, Set. 2019. graf, tab
Artículo en Inglés | Sec. Est. Saúde SP, SESSP-IDPCPROD, Sec. Est. Saúde SP | ID: biblio-1023356

RESUMEN

Background Complex percutaneous coronary intervention (PCI) is associated with higher ischemic risk, which can be mitigated by long-term dual antiplatelet therapy (DAPT). However, concomitant high bleeding risk (HBR) may be present, making it unclear whether short- or long-term DAPT should be prioritized. Objectives This study investigated the effects of ischemic (by PCI complexity) and bleeding (by PRECISE-DAPT [PRE dicting bleeding Complications in patients undergoing stent Implantation and Sub sequent Dual Anti Platelet Therapy] score) risks on clinical outcomes and on the impact of DAPT duration after coronary stenting. Methods Complex PCI was defined as ≥3 stents implanted and/or ≥3 lesions treated, bifurcation stenting and/or stent length >60 mm, and/or chronic total occlusion revascularization. Ischemic and bleeding outcomes in high (≥25) or non-high (<25) PRECISE-DAPT strata were evaluated based on randomly allocated duration of DAPT. Results Among 14,963 patients from 8 randomized trials, 3,118 underwent complex PCI and experienced a higher rate of ischemic, but not bleeding, events. Long-term DAPT in non-HBR patients reduced ischemic events in both complex (absolute risk difference: −3.86%; 95% confidence interval: −7.71 to +0.06) and noncomplex PCI strata (absolute risk difference: −1.14%; 95% confidence interval: −2.26 to −0.02), but not among HBR patients, regardless of complex PCI features. The bleeding risk according to the Thrombolysis In Myocardial Infarction scale was increased by long-term DAPT only in HBR patients, regardless of PCI complexity. Conclusions Patients who underwent complex PCI had a higher risk of ischemic events, but benefitted from long-term DAPT only if HBR features were not present. These data suggested that when concordant, bleeding, more than ischemic risk, should inform decision-making on the duration of DAPT. (AU)


Asunto(s)
Humanos , Enfermedades Cardiovasculares/prevención & control , Evaluación Nutricional , Nutrición, Alimentación y Dieta
5.
Biomed Res Int ; 2019: 3941242, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31179320

RESUMEN

The microbial resistance of fungi and bacteria is currently considered a major public health problem. Esters derived from cinnamic acid have a broad spectrum of pharmacological properties that include antimicrobial activity. In this study, a collection of structurally related 4-chlorocinnamic acid esters was prepared using Fischer esterification reactions, alkyl or aryl halide esterification, and Mitsunobu and Steglich reactions. All of the esters were submitted to antimicrobial tests against strains of the species Candida albicans, Candida glabrata, Candida krusei, Candida guilliermondii, Pseudomonas aeruginosa, and Staphylococcus aureus. The compounds also were subjected to molecular docking study with the enzyme 14α-demethylase. Twelve esters derived from 4-chlorocinnamic acid were obtained, with yields varying from 26.3% to 97.6%, three of which were unpublished. The ester methyl 4-chlorocinnamate (1) presented activity against S. aureus at the highest concentration tested. In the antifungal evaluation, all of the esters were bioactive, but methoxyethyl 4-chlorocinnamate (4) and perillyl 4-chlorocinnamate (11) were the most potent (MIC = 0.13 and 0.024 µmol/mL, respectively). The data of molecular docking suggested that all the compounds present good affinity towards the active site related to antifungal activity. Therefore, the esters tested may be inhibitors of the enzyme 14α-demethylase. In addition, the results demonstrate that substituents of short alkyl chains with presence of heteroatom, such as oxygen, or those with a perillyl type terpenic substructure promote better antifungal profiles.


Asunto(s)
Antiinfecciosos , Candida/crecimiento & desarrollo , Cinamatos , Pseudomonas aeruginosa/crecimiento & desarrollo , Staphylococcus aureus/crecimiento & desarrollo , Antiinfecciosos/química , Antiinfecciosos/farmacología , Cinamatos/química , Cinamatos/farmacología
6.
J Med Chem ; 61(6): 2500-2517, 2018 03 22.
Artículo en Inglés | MEDLINE | ID: mdl-29356532

RESUMEN

Human pancreatic ductal adenocarcinoma (PDAC) involves the dysregulation of multiple signaling pathways. A novel approach to the treatment of PDAC is described, involving the targeting of cancer genes in PDAC pathways having over-representation of G-quadruplexes, using the trisubstituted naphthalene diimide quadruplex-binding compound 2,7-bis(3-morpholinopropyl)-4-((2-(pyrrolidin-1-yl)ethyl)amino)benzo[ lmn][3,8]phenanthroline-1,3,6,8(2 H,7 H)-tetraone (CM03). This compound has been designed by computer modeling, is a potent inhibitor of cell growth in PDAC cell lines, and has anticancer activity in PDAC models, with a superior profile compared to gemcitabine, a commonly used therapy. Whole-transcriptome RNA-seq methodology has been used to analyze the effects of this quadruplex-binding small molecule on global gene expression. This has revealed the down-regulation of a large number of genes, rich in putative quadruplex elements and involved in essential pathways of PDAC survival, metastasis, and drug resistance. The changes produced by CM03 represent a global response to the complexity of human PDAC and may be applicable to other currently hard-to-treat cancers.


Asunto(s)
Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Carcinoma Ductal Pancreático/tratamiento farmacológico , G-Cuádruplex , Neoplasias Pancreáticas/tratamiento farmacológico , Animales , Antimetabolitos Antineoplásicos/farmacología , Carcinoma Ductal Pancreático/genética , Línea Celular Tumoral , Biología Computacional , Simulación por Computador , Daño del ADN , Desoxicitidina/análogos & derivados , Desoxicitidina/farmacología , Regulación hacia Abajo/efectos de los fármacos , Diseño de Fármacos , Resistencia a Antineoplásicos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Ratones , Ratones Desnudos , Neoplasias Pancreáticas/genética , Ensayos Antitumor por Modelo de Xenoinjerto , Gemcitabina
7.
Front Microbiol ; 8: 1673, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28912772

RESUMEN

For over a century, viruses have been known as the most abundant and diverse group of organisms on Earth, forming a virosphere. Based on extensive meta-analyses, we present, for the first time, a wide and complete overview of virus-host network, covering all known viral species. Our data indicate that most of known viral species, regardless of their genomic category, have an intriguingly narrow host range, infecting only 1 or 2 host species. Our data also show that the known virosphere has expanded based on viruses of human interest, related to economical, medical or biotechnological activities. In addition, we provide an overview of the distribution of viruses on different environments on Earth, based on meta-analyses of available metaviromic data, showing the contrasting ubiquity of head-tailed phages against the specificity of some viral groups in certain environments. Finally, we uncovered all human viral species, exploring their diversity and the most affected organic systems. The virus-host network presented here shows an anthropocentric view of the virology. It is therefore clear that a huge effort and change in perspective is necessary to see more than the tip of the iceberg when it comes to virology.

8.
J Cardiovasc Magn Reson ; 18(1): 56, 2016 09 12.
Artículo en Inglés | MEDLINE | ID: mdl-27618813

RESUMEN

BACKGROUND: The increased cardiovascular morbidity of adults with late repair of aortic coarctation (CoA) has been well documented. In contrast, successful CoA repair in early childhood has a generally good prognosis, though adverse vascular and ventricular characteristics may be abnormal, which could increase long-term risk. This study sought to perform a comprehensive analysis of aortic elasticity and left ventricular (LV) function in patients with aortic coarctation (CoA) using cardiovascular magnetic resonance (CMR). In a subgroup of patients, we assessed structure and function of the common carotid arteries to probe for signs of systemic vascular remodeling. METHODS: Fifty-one patients (median age 17.3 years), 13.9 ± 7.5 years after CoA repair, and 54 controls (median age 19.8 years) underwent CMR. We determined distensibility and pulse wave velocity (PWV) at different aortic locations. In a subgroup, common carotid artery distensibility, PWV, wall thickness and wall area were measured. LV ejection fraction (EF), volumes, and mass were measured from short axis views. Left atrial (LA) volumes and functional parameters (LAEFPassive, LAEFContractile, LAEFReservoir) were assessed from axial cine images. RESULTS: In patients distensibility of the whole thoracic aorta was reduced (p < 0.05) while PWV was only significantly higher in the aortic arch (p < 0.01). Distensibility of the descending aorta at the level of the pulmonary arteries and PWV in the descending aorta, both correlated negatively with age at CoA repair. LA volume before atrial contraction and minimal LA volume were higher in patients (p < 0.05). LAEFPassive and LAEFReservoir were reduced (p < 0.05), and LAEFReservoir correlated negatively with aortic arch PWV (p < 0.05). LVEF, volumes and mass were not different from controls. Carotid wall thickness and PWV were higher in patients compared to controls (p < 0.05). CONCLUSIONS: Patients after CoA repair have impaired bioelastic properties of the thoracic aorta with impact on LV diastolic function. Reduced descending aortic elasticity is associated with older age at time of CoA repair. The remodeling of the common carotid artery in our sub-study suggests systemic vessel wall changes.


Asunto(s)
Aorta Torácica/diagnóstico por imagen , Coartación Aórtica/cirugía , Función del Atrio Izquierdo , Procedimientos Quirúrgicos Cardíacos/efectos adversos , Arteria Carótida Común/diagnóstico por imagen , Imagen por Resonancia Cinemagnética , Rigidez Vascular , Adolescente , Adulto , Factores de Edad , Aorta Torácica/fisiopatología , Coartación Aórtica/diagnóstico por imagen , Coartación Aórtica/fisiopatología , Arteria Carótida Común/fisiopatología , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Humanos , Interpretación de Imagen Asistida por Computador , Lactante , Masculino , Valor Predictivo de las Pruebas , Análisis de la Onda del Pulso , Volumen Sistólico , Factores de Tiempo , Resultado del Tratamiento , Remodelación Vascular , Función Ventricular Izquierda , Adulto Joven
9.
Anticancer Agents Med Chem ; 16(12): 1523-1528, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27039922

RESUMEN

Despite constant advances on breast cancer knowledge, the metastatic disease resulting from the spreading of this disease is still a challenge. This scenario is particularly critical in the more aggressive subtypes, as HER2-amplified and triple negative breast cancers, when often occurs the invasion of central nervous system (CNS) structures. In this situation, the survival of patients is drastically reduced, and the number of sequels and functional impairment is huge due to the small therapeutic arsenal available. In this context, it is necessary to understand the mechanisms involved in the process of metastasis of breast cancer to CNS, and how this process affects anatomically important structures for its functioning. This review aims to point out some mechanisms enrolled in the spread of breast cancer to CNS, discuss the clinical impact of such metastatisation and address the critical aspects related to the treatment of this condition.


Asunto(s)
Antineoplásicos/farmacología , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/secundario , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias del Sistema Nervioso Central/tratamiento farmacológico , Neoplasias del Sistema Nervioso Central/secundario , Receptor ErbB-2/antagonistas & inhibidores , Antineoplásicos/química , Neoplasias Encefálicas/diagnóstico , Neoplasias de la Mama/diagnóstico , Neoplasias del Sistema Nervioso Central/diagnóstico , Femenino , Humanos , Receptor ErbB-2/metabolismo
10.
FEMS Microbiol Ecol ; 92(2)2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26610433

RESUMEN

The gastrointestinal tract of vertebrates harbors one of the most complex ecosystems known in microbial ecology and this indigenous microbiota almost always has a profound influence on host-parasite relationships, which can enhance or reduce the pathology of the infection. In this context, the impact of the microbiota during the infection of several viral groups remains poorly studied, including the family Poxviridae. Vaccinia virus (VACV) is a member of this family and is the causative agent of bovine vaccinia, responsible for outbreaks that affect bovines and humans. To determine the influence of the microbiota in the development of the disease caused by VACV, a comparative study using a murine model was performed. Germ-free and conventional, 6- to 7-week-old Swiss NIH mice were infected by tail scarification and intranasally with VACV. Moreover, immunosuppression and microbiota reposition were performed, to establish the interactions among the host's immune system, microbiota and VACV. The data demonstrate that the microbiota is essential for the effective immune response of mice against VACV in intranasal inoculation and to control the virus at the primary site of infection. Furthermore, this study is the first to show that Swiss conventional mice are refractory to the intranasal infection of VACV.


Asunto(s)
Tracto Gastrointestinal/microbiología , Interacciones Huésped-Patógeno/inmunología , Microbiota/inmunología , Virus Vaccinia/inmunología , Vaccinia/inmunología , Animales , Bovinos , Enfermedades de los Bovinos/inmunología , Enfermedades de los Bovinos/virología , Humanos , Ratones , Vaccinia/virología
11.
Clinics (Sao Paulo) ; 64(5): 435-42, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19488610

RESUMEN

OBJECTIVES: To compare the metabolic, hemodynamic, autonomic, and endothelial responses to short-term red wine consumption in subjects with hypercholesterolemia or arterial hypertension, and healthy controls. METHODS: Subjects with hypercholesterolemia (n=10) or arterial hypertension (n=9), or healthy controls (n=7) were given red wine (250 mL/night) for 15 days. Analyses were performed before and after red wine intake. RESULTS: Red wine significantly increased the plasma levels of HDL-cholesterol in the controls, but not in the other groups. The effects on hemodynamic measurements were mild, non-significantly more prominent in healthy subjects, and exhibited high interindividual variability. Across all participants, mean blood pressure decreased 7 mmHg (p <0.01) and systemic vascular resistance decreased 7% (p = 0.05). Heart rate and cardiac output did not significantly change in any group. Red wine enhanced muscle sympathetic fibular nerve activity in hypercholesterolemic and hypertensive patients, but not in controls. At baseline, brachial artery flow-mediated dilation was impaired in patients with hypercholesterolemia and arterial hypertension; red wine restored the dilation in the hypercholesterolemic group but not in the hypertensive group. CONCLUSIONS: Red wine elicits different metabolic, autonomic, and endothelial responses among individuals with hypercholesterolemia or arterial hypertension and healthy controls. Our findings highlight the need to consider patient characteristics when evaluating the response to red wine.


Asunto(s)
HDL-Colesterol/sangre , Endotelio Vascular/efectos de los fármacos , Hipercolesterolemia/tratamiento farmacológico , Hipertensión/tratamiento farmacológico , Sistema Nervioso Simpático/efectos de los fármacos , Vino , Adulto , Consumo de Bebidas Alcohólicas/sangre , Análisis de Varianza , Presión Sanguínea/efectos de los fármacos , Estudios de Casos y Controles , HDL-Colesterol/efectos de los fármacos , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Masculino , Persona de Mediana Edad
12.
Conserv Biol ; 20(3): 853-60, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16909577

RESUMEN

Little is known about how the surrounding modified matrix affects tree recruitment in fragmented forests. We contrasted effects of two different matrix types, Vismia- and Cecropia-dominated regrowth, on recruitment of pioneer tree species in forest fragments in central Amazonia. Our analyses were based on 22, 1-ha plots in seven experimental forest fragments ranging in size from 1 to 100 ha. By 13 to 17 years after fragmentation, the population density of pioneer trees was significantly higher in plots surrounded by Vismia regrowth than in plots surrounded by Cecropia regrowth, and the species composition and dominance of pioneers differed markedly between the two matrix types. Cecropia sciadophylla was the most abundant pioneer in fragments surrounded by Cecropia regrowth (constituting nearly 50% of all pioneer trees), whereas densities of species in Vismia-surrounded fragments were distributed more evenly. Thus the surrounding matrix had a strong influence on patterns of tree recruitment in Amazonian forest fragments.


Asunto(s)
Ecosistema , Árboles/fisiología , Conservación de los Recursos Naturales , Dinámica Poblacional , Especificidad de la Especie
13.
Ecology ; 87(2): 469-82, 2006 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-16637371

RESUMEN

The effects of habitat fragmentation on diverse tropical tree communities are poorly understood. Over a 20-year period we monitored the density of 52 tree species in nine predominantly successional genera (Annona, Bellucia, Cecropia, Croton, Goupia, Jacaranda, Miconia, Pourouma, Vismia) in fragmented and continuous Amazonian forests. We also evaluated the relative importance of soil, topographic, forest dynamic, and landscape variables in explaining the abundance and species composition of successional trees. Data were collected within 66 permanent 1-ha plots within a large (approximately 1000 km2) experimental landscape, with forest fragments ranging from 1 to 100 ha in area. Prior to forest fragmentation, successional trees were uncommon, typically comprising 2-3% of all trees (> or =10 cm diameter at breast height [1.3 m above the ground surface]) in each plot. Following fragmentation, the density and basal area of successional trees increased rapidly. By 13-17 years after fragmentation, successional trees had tripled in abundance in fragment and edge plots and constituted more than a quarter of all trees in some plots. Fragment age had strong, positive effects on the density and basal area of successional trees, with no indication of a plateau in these variables, suggesting that successional species could become even more abundant in fragments over time. Nonetheless, the 52 species differed greatly in their responses to fragmentation and forest edges. Some disturbance-favoring pioneers (e.g., Cecropia sciadophylla, Vismia guianensis, V. amazonica, V. bemerguii, Miconia cf. crassinervia) increased by >1000% in density on edge plots, whereas over a third (19 of 52) of all species remained constant or declined in numbers. Species responses to fragmentation were effectively predicted by their median growth rate in nearby intact forest, suggesting that faster-growing species have a strong advantage in forest fragments. An ordination analysis revealed three main gradients in successional-species composition across our study area. Species gradients were most strongly influenced by the standlevel rate of tree mortality on each plot and by the number of nearby forest edges. Species-composition also varied significantly among different cattle ranches, which differed in their surrounding matrices and disturbance histories. These same variables were also the best predictors of total successional-tree abundance and species richness. Successional-tree assemblages in fragment interior plots (>150 m from edge), which are subjected to fragment area effects but not edge effects, did not differ significantly from those in intact forest, indicating that area effects per se had little influence on successional trees. Soils and topography also had little discernable effect on these species. Collectively, our results indicate that successional-tree species proliferate rapidly in fragmented Amazonian forests, largely as a result of chronically elevated tree mortality near forest edges and possibly an increased seed rain from successional plants growing in nearby degraded habitats. The proliferation of fast-growing successional trees and correlated decline of old-growth trees will have important effects on species composition, forest dynamics, carbon storage, and nutrient cycling in fragmented forests.


Asunto(s)
Árboles/crecimiento & desarrollo , Brasil , Especificidad de la Especie
14.
Atherosclerosis ; 187(1): 116-22, 2006 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16458316

RESUMEN

Fasting hypertriglyceridemia relates with high-density lipoprotein (HDL) cholesterol, but it is not known whether low HDL cholesterol is associated with disturbances of chylomicron metabolism. To clarify this issue this metabolism was studied in subjects with low HDL cholesterol together with vascular reactivity and evaluation of no-flush niacin treatment. Thirty men with HDL < 1.04 mmol/L and no other risk factors for coronary artery disease (CAD) and 11 normal controls with HDL > 1.04 mmol/L were studied. The plasma kinetics of a chylomicron-like emulsion labeled with 14C-cholesterol oleate (CO) and 3H-triolein (TG) was determined and the fractional clearance rate (FCR, min(-1)) was calculated. Vascular reactivity was evaluated using high-resolution ultrasonography. CO FCR was markedly reduced in the low HDL group compared to controls (3.6 x 10(-3) +/- 5.1 x 10(-3) min(-1) versus 12.2 x 10(-3) +/- 8.4 x 10(-3) min(-1), p < 0.001) but TG FCR was similar. Flow-mediated dilation (FMD) was diminished in low HDL (7.4 +/- 4.1 versus 12.8 +/- 4.6%, p < 0.001), whereas nitrate-mediated dilation was similar. Twenty-two low HDL subjects with reduced FMD were randomized into two groups, one given 1.5 g/day niacin and a placebo group. After 3-month treatment, plasma lipids and chylomicron kinetics were not changed by niacin treatment but FMD improved to normal values (5.44 +/- 1.89 to 11.13 +/- 3.4%, p < 0.01). In conclusion, isolated low HDL cholesterol subjects may also bear chylomicron remnant accumulation and endothelial dysfunction, which highlight the importance of their preventive treatment.


Asunto(s)
Arteria Braquial/efectos de los fármacos , HDL-Colesterol/metabolismo , Quilomicrones/química , Hipolipemiantes/farmacología , Lipoproteínas/química , Niacina/farmacología , Adulto , Anciano , Quilomicrones/metabolismo , Emulsiones , Humanos , Cinética , Masculino , Persona de Mediana Edad , Triglicéridos/química , Triglicéridos/metabolismo
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