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1.
Front Ecol Environ ; 11: 1-16, 2023 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-38516293

RESUMO

Environmental decision-making benefits from considering ecosystem services to ensure that aspects of the environment that people rely upon are fully evaluated. By focusing consideration of ecosystem services on final ecosystem goods and services (FEGS), the aspects of the environment directly enjoyed, used, or consumed by humans, these analyses can be more streamlined and effective. The U.S. Environmental Protection Agency has developed a set of tools to facilitate this consideration. The central feature of FEGS is that ecosystems are viewed through the diverse ways people directly benefit from them. The National Ecosystem Services Classification System (NESCS) Plus provides a framework for describing and identifying FEGS consistently. The standardization made available by NESCS Plus allows other tools and databases to interact using the NESCS Plus architecture and taxonomy, providing diverse insights for decision makers. Here, we examine the synergy of using the following four tools together: (1) the FEGS Scoping Tool; (2) the FEGS Metrics Report; (3) the EnviroAtlas; and (4) the EcoService Models Library. The FEGS Scoping Tool helps users determine what ecosystem services are relevant to a decision by harnessing FEGS understanding to enable communities to identify the relative importance of beneficiaries relevant to a decision and biophysical aspects of the environment of direct relevance to those beneficiaries. The FEGS Metrics Report can guide which metrics to monitor or model to represent those priority services. The EnviroAtlas, a powerful tool containing geospatial data and other resources related to ecosystem services, chemical and non-chemical stressors, and human health, and the EcoService Models Library, a database of ecosystem models, are two tools that support users in mapping and modeling endpoints relevant to priority services. While each of these tools is valuable on its own, together, they provide a powerful approach to easily incorporate and operationalize ecosystem services efforts into different parts of decision-making processes across different types of decisions. We illustrate how these integrated tools can be used together with a hypothetical example of a complex environmental management case study and the combined benefit of using the FEGS tools together.

2.
Am J Addict ; 31(5): 433-440, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35411688

RESUMO

BACKGROUND AND OBJECTIVES: Despite overwhelming evidence of benefit, medications for opioid use disorder (MOUD) remain stigmatizing and more efforts are needed to educate health care professionals and the general public. METHODS: We developed and evaluated an educational program for graduate students studying health sciences, teaching them to deliver 1 h presentations to the community on the opioid crisis and the usefulness of MOUD. RESULTS: To date, 120 graduate students have participated in this training experience on substance use disorders and delivered 59 presentations to more than 1065 community members. We found a significant increase in knowledge among students following the training. In addition, although attitudes and beliefs were generally positive at baseline, we also found significant increases in positives attitudes about the treatment of addiction and working with patients with addictions. Almost all students believed the course enhanced their professional expertise and would recommend it to others. We compared our students' baseline knowledge and attitudes to a large sample of other graduate students and did not find significant differences indicating good external validity of our results. Finally, we evaluated change in community members' knowledge and attitudes (N = 315) following student presentations and found significant increases in knowledge and positive attitude change toward MOUD. DISCUSSION AND CONCLUSIONS: Overall our program was feasible, enjoyable, and effective in meeting its goals of increasing knowledge acquisition and improving attitudes among students and the greater community. SCIENTIFIC SIGNIFICANCE: Graduate students in health sciences can be trained to successfully teach the public about the opioid crisis and the usefulness of MOUD.


Assuntos
Analgésicos Opioides , Transtornos Relacionados ao Uso de Opioides , Analgésicos Opioides/uso terapêutico , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Epidemia de Opioides , Transtornos Relacionados ao Uso de Opioides/tratamento farmacológico , Transtornos Relacionados ao Uso de Opioides/epidemiologia , Estudantes
3.
J Pers Med ; 11(6)2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34204946

RESUMO

The inherited mutation (R14del) in the calcium regulatory protein phospholamban (PLN) is linked to malignant ventricular arrhythmia with poor prognosis starting at adolescence. However, the underlying early mechanisms that may serve as prognostic factors remain elusive. This study generated humanized mice in which the endogenous gene was replaced with either human wild type or R14del-PLN and addressed the early molecular and cellular pathogenic mechanisms. R14del-PLN mice exhibited stress-induced impairment of atrioventricular conduction, and prolongation of both ventricular activation and repolarization times in association with ventricular tachyarrhythmia, originating from the right ventricle (RV). Most of these distinct electrocardiographic features were remarkably similar to those in R14del-PLN patients. Studies in isolated cardiomyocytes revealed RV-specific calcium defects, including prolonged action potential duration, depressed calcium kinetics and contractile parameters, and elevated diastolic Ca-levels. Ca-sparks were also higher although SR Ca-load was reduced. Accordingly, stress conditions induced after contractions, and inclusion of the CaMKII inhibitor KN93 reversed this proarrhythmic parameter. Compensatory responses included altered expression of key genes associated with Ca-cycling. These data suggest that R14del-PLN cardiomyopathy originates with RV-specific impairment of Ca-cycling and point to the urgent need to improve risk stratification in asymptomatic carriers to prevent fatal arrhythmias and delay cardiomyopathy onset.

4.
J Environ Manage ; 262: 110262, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32250778

RESUMO

The preservation of salt marshes under rapid sea-level rise (SLR) typically requires the conservation of marsh transgression zones-undeveloped uplands onto which marshes can migrate. Optimal planning for conservation of this type requires information on the expected benefit of marsh conservation and the cost of land suitable for marsh migration in particular areas. While information is available on marsh benefits within the literature, prior research provides little insight on associated land conservation costs. The coastal hedonic pricing literature focuses primarily on developed land, and there are no models designed to predict the cost of conserving land suitable for marsh migration. This paper develops a hedonic property value model to predict cost and explore price patterns associated with purchases of undeveloped land suitable for salt marsh migration under SLR. The model is illustrated using a case study from the Eastern Shore of Virginia, with a dataset consisting of open-market sales of undeveloped land from 2014 to 2017. Particular attention is paid to characteristics that determine marsh migration potential such as coastal distance, elevation and connectivity. Results demonstrate the insight for conservation planning that can be provided by models of this type and the errors associated with the use of simplified proxies to predict conservation costs of land suitable for marsh migration.


Assuntos
Conservação dos Recursos Naturais , Áreas Alagadas , Análise Custo-Benefício , Virginia
5.
J Biol Chem ; 294(48): 18057-18068, 2019 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-31619520

RESUMO

Cardiac mitochondrial damage and subsequent inflammation are hallmarks of endotoxin-induced myocardial depression. Activation of the Parkin/PTEN-induced kinase 1 (PINK1) pathway has been shown to promote autophagy of damaged mitochondria (mitophagy) and to protect from endotoxin-induced cardiac dysfunction. Tumor susceptibility gene 101 (TSG101) is a key member of the endosomal recycling complexes required for transport, which may affect autophagic flux. In this study, we investigated whether TSG101 regulates mitophagy and influences the outcomes of endotoxin-induced myocardial dysfunction. TSG101 transgenic and knockdown mice underwent endotoxin/lipopolysaccharide treatment (10 µg/g) and were assessed for survival, cardiac function, systemic/local inflammation, and activity of mitophagy mediators in the heart. Upon endotoxin challenge and compared with WT mice, TSG101 transgenic mice exhibited increased survival, preserved cardiac contractile function, reduced inflammation, and enhanced mitophagy activation in the heart. By contrast, TSG101 knockdown mice displayed opposite phenotypes during endotoxemia. Mechanistically, both coimmunoprecipitation assays and coimmunofluorescence staining revealed that TSG101 directly binds to Parkin in the cytosol of myocytes and facilitates translocation of Parkin from the cytosol to the mitochondria. Our results indicate that TSG101 elevation could protect against endotoxin-triggered myocardial injury by promoting Parkin-induced mitophagy.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Cardiopatias/metabolismo , Lipopolissacarídeos/toxicidade , Mitocôndrias Cardíacas/metabolismo , Mitofagia/efeitos dos fármacos , Fatores de Transcrição/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Proteínas de Ligação a DNA/genética , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Cardiopatias/induzido quimicamente , Cardiopatias/genética , Cardiopatias/patologia , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias Cardíacas/genética , Mitocôndrias Cardíacas/patologia , Mitofagia/genética , Contração Miocárdica/efeitos dos fármacos , Contração Miocárdica/genética , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Fatores de Transcrição/genética , Ubiquitina-Proteína Ligases/genética
6.
JACC Basic Transl Sci ; 4(2): 188-199, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31061921

RESUMO

Cardiomyocyte-specific increases in phosphorylated Hsp20 (S16D-Hsp20) to levels similar to those observed in human failing hearts are associated with early fibrotic remodeling and depressed left ventricular function, symptoms which progress to heart failure and early death. The underlying mechanisms appear to involve translocation of phosphorylated Hsp20 to the nucleus and upregulation of interleukin (IL)-6, which subsequently activates cardiac fibroblasts in a paracrine fashion through transcription factor STAT3 signaling. Accordingly, treatment of S16D-Hsp20 mice with a rat anti-mouse IL-6 receptor monoclonal antibody (MR16-1) attenuated interstitial fibrosis and preserved cardiac function. These findings suggest that phosphorylated Hsp20 may be a potential therapeutic target in heart failure.

7.
J Cell Mol Med ; 22(8): 3911-3919, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29761889

RESUMO

Heat shock protein 20 (Hsp20) has been shown to be a critical regulator of cardiomyocyte survival upon cardiac stress. In this study, we investigated the functional significance of a novel human Hsp20 mutation (S10F) in peripartum cardiomyopathy. Previous findings showed that cardiac-specific overexpression of this mutant were associated with reduced autophagy, left ventricular dysfunction and early death in male mice. However, this study indicates that females have normal function with no alterations in autophagy but died within a week after 1-4 pregnancies. Further examination of mutant females revealed left ventricular chamber dilation and hypertrophic remodelling. Echocardiography demonstrated increases in left ventricular end-systolic volume and left ventricular end-diastolic volume, while ejection fraction and fractional shortening were depressed following pregnancy. Subsequent studies revealed that cardiomyocyte apoptosis was elevated in mutant female hearts after the third delivery, associated with decreases in the levels of Bcl-2/Bax and Akt phosphorylation. These results indicate that the human S10F mutant is associated with dysregulation of cell survival signalling, accelerated heart failure and early death post-partum.

8.
J Mol Cell Cardiol ; 119: 125-137, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29698635

RESUMO

Though experimental, stem cell transplantation has the potential to improve the condition of the heart after myocardial infarction. It does so by reducing infarct size and inducing repair of heart muscle and its blood supply. Mesenchymal stem cells (MSC) have been found to be effective in pre-clinical animal models and clinical trials, but the mechanisms by which they induce cardioprotection and repair are still not fully understood. Small extracellular vesicles known as exosomes are now recognized to be key mediators of beneficial MSC paracrine effects, and the concept that they transfer miRNA to change gene expression in recipient cells is of current therapeutic interest. We present complete deep miRNA sequencing of MSC exosome cargo, and found that of several cardioprotective miRNAs, miR-21a-5p was the most abundant. Because miR-21a-5p is a well-known cardioprotective miRNA, we investigated the hypothesis that MSC exosomes can cardioprotect the heart by increasing the level of miR-21a-5p in recipient cardiac cells, thereby downregulating expression of the pro-apoptotic gene products PDCD4, PTEN, Peli1 and FasL in the myocardium. Using miR-21 mimic transfection and treatment with wild type and miR-21a knockout MSC exosomes, we confirmed that exosomal miR-21a-5p is transferred into myocardium and is a major cardioprotective paracrine factor produced by MSCs acting via synergistic activity on multiple pathways. The data supports that residual cardioprotective effect may be due to other ncRNA or protein cargo. In silico analyses support that MSC exosomes may also contribute to angiogenesis, cell proliferation and other aspects of cardiac repair.


Assuntos
Exossomos/genética , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/metabolismo , MicroRNAs/genética , Animais , Linhagem Celular , Proliferação de Células/genética , Exossomos/metabolismo , Técnicas de Inativação de Genes , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Camundongos , Infarto do Miocárdio/genética , Infarto do Miocárdio/patologia , Miocárdio/metabolismo , Miocárdio/patologia , Neovascularização Patológica/genética , Neovascularização Patológica/patologia , Ratos
9.
J Neurosci ; 38(18): 4316-4328, 2018 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-29626166

RESUMO

In human drug users, cue-induced drug craving progressively intensifies after drug abstinence, promoting drug relapse. This time-dependent progression of drug craving is recapitulated in rodent models, in which rats exhibit progressive intensification of cue-induced drug seeking after withdrawal from drug self-administration, a phenomenon termed incubation of drug craving. Although recent results suggest that functional alterations of the nucleus accumbens (NAc) contribute to incubation of drug craving, it remains poorly understood how NAc function evolves after drug withdrawal to progressively intensify drug seeking. The functional output of NAc relies on how the membrane excitability of its principal medium spiny neurons (MSNs) translates excitatory synaptic inputs into action potential firing. Here, we report a synapse-membrane homeostatic crosstalk (SMHC) in male rats, through which an increase or decrease in the excitatory synaptic strength induces a homeostatic decrease or increase in the intrinsic membrane excitability of NAc MSNs, and vice versa. After short-term withdrawal from cocaine self-administration, despite no actual change in the AMPA receptor-mediated excitatory synaptic strength, GluN2B NMDA receptors, the SMHC sensors of synaptic strength, are upregulated. This may create false SMHC signals, leading to a decrease in the membrane excitability of NAc MSNs. The decreased membrane excitability subsequently induces another round of SMHC, leading to synaptic accumulation of calcium-permeable AMPA receptors and upregulation of excitatory synaptic strength after long-term withdrawal from cocaine. Disrupting SMHC-based dysregulation cascades after cocaine exposure prevents incubation of cocaine craving. Thus, cocaine triggers cascades of SMHC-based dysregulation in NAc MSNs, promoting incubated cocaine seeking after drug withdrawal.SIGNIFICANCE STATEMENT Here, we report a bidirectional homeostatic plasticity between the excitatory synaptic input and membrane excitability of nucleus accumbens (NAc) medium spiny neurons (MSNs), through which an increase or decrease in the excitatory synaptic strength induces a homeostatic decrease or increase in the membrane excitability, and vice versa. Cocaine self-administration creates a false homeostatic signal that engages this synapse-membrane homeostatic crosstalk mechanism, and produces cascades of alterations in excitatory synapses and membrane properties of NAc MSNs after withdrawal from cocaine. Experimentally preventing this homeostatic dysregulation cascade prevents the progressive intensification of cocaine seeking after drug withdrawal. These results provide a novel mechanism through which drug-induced homeostatic dysregulation cascades progressively alter the functional output of NAc MSNs and promote drug relapse.


Assuntos
Transtornos Relacionados ao Uso de Cocaína/fisiopatologia , Fissura , Homeostase , Potenciais de Ação , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Transtornos Relacionados ao Uso de Cocaína/psicologia , Sinais (Psicologia) , Comportamento de Procura de Droga , Potenciais Pós-Sinápticos Excitadores , Quinases do Centro Germinativo , Masculino , Plasticidade Neuronal , Neurônios , Núcleo Accumbens/patologia , Proteínas Serina-Treonina Quinases/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismo , Síndrome de Abstinência a Substâncias/patologia , Síndrome de Abstinência a Substâncias/psicologia , Sinapses
10.
J Mol Cell Cardiol ; 114: 220-233, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29169992

RESUMO

Ischemia/reperfusion injury is associated with contractile dysfunction and increased cardiomyocyte death. Overexpression of the hematopoietic lineage substrate-1-associated protein X-1 (HAX-1) has been shown to protect from cellular injury but the function of endogenous HAX-1 remains obscure due to early lethality of the knockout mouse. Herein we generated a cardiac-specific and inducible HAX-1 deficient model, which uncovered an unexpected role of HAX-1 in regulation of sarco/endoplasmic reticulum Ca-ATPase (SERCA2a) in ischemia/reperfusion injury. Although ablation of HAX-1 in the adult heart elicited no morphological alterations under non-stress conditions, it diminished contractile recovery and increased infarct size upon ischemia/reperfusion injury. These detrimental effects were associated with increased loss of SERCA2a. Enhanced SERCA2a degradation was not due to alterations in calpain and calpastatin levels or calpain activity. Conversely, HAX-1 overexpression improved contractile recovery and maintained SERCA2a levels. The regulatory effects of HAX-1 on SERCA2a degradation were observed at multiple levels, including intact hearts, isolated cardiomyocytes and sarcoplasmic reticulum microsomes. Mechanistically, HAX-1 ablation elicited increased production of reactive oxygen species at the sarco/endoplasic reticulum compartment, resulting in SERCA2a oxidation and a predisposition to its proteolysis. This effect may be mediated by NAPDH oxidase 4 (NOX4), a novel binding partner of HAX-1. Accordingly, NOX inhibition with apocynin abrogated the effects of HAX-1 ablation in hearts subjected to ischemia/reperfusion injury. Taken together, our findings reveal a role of HAX-1 in the regulation of oxidative stress and SERCA2a degradation, implicating its importance in calcium homeostasis and cell survival pathways.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas/metabolismo , Proteólise , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Idoso , Animais , Calpaína/metabolismo , Retículo Endoplasmático/metabolismo , Feminino , Deleção de Genes , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/patologia , Insuficiência Cardíaca/fisiopatologia , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Contração Miocárdica , Traumatismo por Reperfusão Miocárdica/patologia , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Miocárdio/patologia , Miócitos Cardíacos/metabolismo , NADPH Oxidase 4/metabolismo , Oxirredução , Estresse Oxidativo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Recuperação de Função Fisiológica , Retículo Sarcoplasmático/metabolismo
11.
Autophagy ; 14(1): 80-97, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29157081

RESUMO

HSPB6/Hsp20 (heat shock protein family B [small] member 6) has emerged as a novel cardioprotector against stress-induced injury. We identified a human mutant of HSPB6 (HSPB6S10F) exclusively present in dilated cardiomyopathy (DCM) patients. Cardiac expression of this mutant in mouse hearts resulted in remodeling and dysfunction, which progressed to heart failure and early death. These detrimental effects were associated with reduced interaction of mutant HSPB6S10F with BECN1/Beclin 1, leading to BECN1 ubiquitination and its proteosomal degradation. As a result, autophagy flux was substantially inhibited and apoptosis was increased in HSPB6S10F-mutant hearts. In contrast, overexpression of wild-type HSPB6 (HSPB6 WT) not only increased BECN1 levels, but also competitively suppressed binding of BECN1 to BCL2, resulting in stimulated autophagy. Indeed, preinhibition of autophagy attenuated the cardioprotective effects of HSPB6 WT. Taken together, these findings reveal a new regulatory mechanism of HSPB6 in cell survival through its interaction with BECN1. Furthermore, Ser10 appears to be crucial for the protective effects of HSPB6 and transversion of this amino acid to Phe contributes to cardiomyopathy.


Assuntos
Autofagia , Proteína Beclina-1/metabolismo , Cardiomiopatia Dilatada , Proteínas de Choque Térmico HSP20/genética , Proteínas de Choque Térmico HSP20/metabolismo , Miócitos Cardíacos/metabolismo , Animais , Apoptose , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/patologia , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/patologia , Humanos , Camundongos , Camundongos Transgênicos , Mutação , Miócitos Cardíacos/patologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Ratos Sprague-Dawley , Ubiquitinação
12.
Proc Natl Acad Sci U S A ; 112(47): E6466-75, 2015 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-26553996

RESUMO

The major underpinning of massive cell death associated with myocardial infarction involves opening of the mitochondrial permeability transition pore (mPTP), resulting in disruption of mitochondria membrane integrity and programmed necrosis. Studies in human lymphocytes suggested that the hematopoietic-substrate-1 associated protein X-1 (HAX-1) is linked to regulation of mitochondrial membrane function, but its role in controlling mPTP activity remains obscure. Herein we used models with altered HAX-1 expression levels in the heart and uncovered an unexpected role of HAX-1 in regulation of mPTP and cardiomyocyte survival. Cardiac-specific HAX-1 overexpression was associated with resistance against loss of mitochondrial membrane potential, induced by oxidative stress, whereas HAX-1 heterozygous deficiency exacerbated vulnerability. The protective effects of HAX-1 were attributed to specific down-regulation of cyclophilin-D levels leading to reduction in mPTP activation. Accordingly, cyclophilin-D and mPTP were increased in heterozygous hearts, but genetic ablation of cyclophilin-D in these hearts significantly alleviated their susceptibility to ischemia/reperfusion injury. Mechanistically, alterations in cyclophilin-D levels by HAX-1 were contributed by the ubiquitin-proteosomal degradation pathway. HAX-1 overexpression enhanced cyclophilin-D ubiquitination, whereas proteosomal inhibition restored cyclophilin-D levels. The regulatory effects of HAX-1 were mediated through interference of cyclophilin-D binding to heat shock protein-90 (Hsp90) in mitochondria, rendering it susceptible to degradation. Accordingly, enhanced Hsp90 expression in HAX-1 overexpressing cardiomyocytes increased cyclophilin-D levels, as well as mPTP activation upon oxidative stress. Taken together, our findings reveal the role of HAX-1 in regulating cyclophilin-D levels via an Hsp90-dependent mechanism, resulting in protection against activation of mPTP and subsequent cell death responses.


Assuntos
Ciclofilinas/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Miocárdio/metabolismo , Proteínas/metabolismo , Adenoviridae/metabolismo , Animais , Cálcio/metabolismo , Morte Celular , Peptidil-Prolil Isomerase F , Proteínas de Choque Térmico HSP90/metabolismo , Heterozigoto , Humanos , Técnicas In Vitro , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Camundongos , Membranas Mitocondriais/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Miócitos Cardíacos/metabolismo , Estresse Oxidativo , Ligação Proteica , Transporte Proteico , Proteólise , Ratos Sprague-Dawley , Ubiquitinação
13.
Comp Biochem Physiol C Toxicol Pharmacol ; 138(3): 375-81, 2004 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15533795

RESUMO

A high prevalence of germinomas has been observed in certain populations of Mya arenaria from eastern Maine. The etiology of these tumors is unknown. We are investigating the hypothesis that exposure to environmental contaminants, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) contributes to gonadal carcinogenesis. Clams were exposed to TCDD with or without the initiating compound diethylnitrosamine (DEN) in an attempt to induce germinomas. A TCDD-dependent alteration in gametogenesis was observed in which 32.5+/-6.5% of individuals exhibited undifferentiated gonads. Analyses of AhR and p53 expression were carried out to identify similarities between naturally occurring neoplastic and TCDD (+/-DEN)-altered reproductive tissues. Neoplastic tissues had significantly less p53 protein than matched controls, whereas TCDD-induced undifferentiated samples exhibited no difference in p53 protein levels compared to controls. No gender-specific differences were observed in AhR mRNA, but there were significant differences in protein levels. AhR was undetectable in male gonadal tissue whereas females exhibited a significant positive relationship between AhR protein levels and stage of ovogenesis. Despite exhibiting some morphological similarity, we conclude the TCDD-induced pathology is not a germinoma. We further suggest the change in reproductive tissue is due to inhibition of cell differentiation and/or development by an AhR-independent mechanism.


Assuntos
Genitália/efeitos dos fármacos , Moluscos/efeitos dos fármacos , Moluscos/fisiologia , Dibenzodioxinas Policloradas/farmacologia , Receptores de Hidrocarboneto Arílico/metabolismo , Animais , Dietilnitrosamina/farmacologia , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Genitália/metabolismo , Genitália/patologia , Masculino , Neoplasias de Tecido Gonadal/induzido quimicamente , Neoplasias de Tecido Gonadal/etiologia , Neoplasias de Tecido Gonadal/genética , Neoplasias de Tecido Gonadal/patologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteína Supressora de Tumor p53/metabolismo
14.
Nature ; 397(6718): 423-425, 1999 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-29667969

RESUMO

The oligotrophic gyres of the open sea are home to a flora that includes the largest known phytoplankton. These rare species migrate as solitary cells or aggregations (mats) between deep nutrient pools (below 80-100 m) and the surface. This migration contributes to new production because of the concomitant upward transport of nitrate. But just how significant this contribution is remains uncertain because of the difficulty of making quantitative measurements of these rare cells. Here we report remote video observations of a previously undersampled class of diatom (Rhizosolenia) mats throughout the upper 150 m of the central North Pacific Ocean. These mats are virtually invisible to divers, and their presence increases the calculated phytoplankton-mediated nitrate transport into the surface ocean by up to a factor of eight. Cruise averages indicate that Rhizosolenia mats transport 18-97 µmol N m-2 d-1; however, this value reached 171 µmol N m-2 d-1 at individual stations, a value equivalent to 59% of the export production. Although considerable temporal and spatial variability occurs, this means of upward nutrient transport appears to be an important source of new nitrogen to the surface ocean, and may contribute to other regional elemental cycles as well.

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