RESUMO
Scientists and managers of natural resources have recognized an urgent need for improved methods and tools to enable effective adaptation of management measures in the face of climate change. This paper presents an Adaptation Design Tool that uses a structured approach to break down an otherwise overwhelming and complex process into tractable steps. The tool contains worksheets that guide users through a series of design considerations for adapting their planned management actions to be more climate-smart given changing environmental stressors. Also provided with other worksheets is a framework for brainstorming new adaptation options in response to climate threats not yet addressed in the current plan. Developed and tested in collaboration with practitioners in Hawai'i and Puerto Rico using coral reefs as a pilot ecosystem, the tool and associated reference materials consist of worksheets, instructions and lessons-learned from real-world examples. On the basis of stakeholder feedback from expert consultations during tool development, we present insights and recommendations regarding how to maximize tool efficiency, gain the greatest value from the thought process, and deal with issues of scale and uncertainty. We conclude by reflecting on how the tool advances the theory and practice of assessment and decision-making science, informs higher level strategic planning, and serves as a platform for a systematic, transparent and inclusive process to tackle the practical implications of climate change for management of natural resources.
Assuntos
Mudança Climática , Conservação dos Recursos Naturais/métodos , Recifes de Corais , Recursos Naturais , Tomada de Decisões , Ecossistema , Havaí , Porto Rico , Projetos de PesquisaRESUMO
The TLR7 and TLR9 signalings are implicated in the regulation of the immune system through type-I interferon induction. Preclinical studies have demonstrated the immunomodulatory and antitumor effects of TLR7 and TLR9 agonists in combination with cetuximab. We tested the hypothesis that genetic variations in TLR7 and TLR9 and their downstream molecules IRF5 and IRF7 were associated with outcomes in metastatic colorectal cancer (mCRC) patients receiving cetuximab-based chemotherapy. Six single nucleotide polymorphisms (SNPs) in TLR7, TLR9, IRF5 and IRF7 were tested for the association with RR, PFS, and OS in KRAS-wild type mCRC patients. Patients treated with FOLFIRI + cetuximab or FOLFIRI + bevacizumab in the FIRE-3 trial served as a discovery set (FIRE3-Cet, n = 244) or a control set (FIRE3-Bev, n = 246), respectively. Patients treated with FOLFOX or SOX + cetuximab in the JACCRO-CC05/06 trial served as a validation set (JACCRO, n = 76). Genomic DNA isolated from tumor tissue samples was analyzed by PCR-based direct sequencing. In the discovery cohort, patients with the TLR7 rs3853839 G/G variant showed a trend toward longer PFS than those with any C variants (median 10.0 vs. 11.8 months, HR 1.39, p = 0.092). This preliminary association was confirmed in the validation cohort, and those with the G/G genotype showed a PFS benefit compared with others (univariate: 9.1 vs. 11.6 months, HR 2.04, p = 0.005, multivariate: HR 2.02, 95% CI: 1.14-3.55, p = 0.015). This association was not observed in the control cohort. Our findings suggest that TLR7 rs3853839 predicts the outcome of cetuximab-based chemotherapy in mCRC patients.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Receptor 7 Toll-Like/genética , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Camptotecina/administração & dosagem , Camptotecina/análogos & derivados , Cetuximab/administração & dosagem , Ensaios Clínicos Fase II como Assunto , Ensaios Clínicos Fase III como Assunto , Neoplasias Colorretais/patologia , Intervalo Livre de Doença , Feminino , Fluoruracila/administração & dosagem , Humanos , Leucovorina/administração & dosagem , Masculino , Pessoa de Meia-Idade , Estudos Multicêntricos como Assunto , Metástase Neoplásica , Polimorfismo de Nucleotídeo Único , Valor Preditivo dos Testes , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Ensaios Clínicos Controlados Aleatórios como Assunto , Receptor 7 Toll-Like/biossínteseRESUMO
The Insulin-like growth factor (IGF)/IGF-receptor pathway with its scaffolding proteins Insulin Receptor Substrate (IRS)1 and IRS2 are crucial regulators of metabolism and progression in metastatic colorectal cancer (mCRC). The goal of the study was the identification of predictive and prognostic markers among IRS1, IRS2, IGF1 and IGF-1R SNPs in mCRC patients enrolled in the FIRE-3 trial. Four SNPs of IRS (IRS1 rs1801278, rs1801123; IRS2 rs1805097, rs2289046) and four SNPs of IGF1-IGFR1 (rs6214, rs6220, rs2946834, rs2016347) were analyzed by PCR/direct-sequencing in the FIRE-3 trial. The relation of SNPs with PFS and OS was evaluated through Kaplan-Meier method and log-rank test in the overall population and in subgroup according to RAS status and treatment arm. In the overall population IRS1 rs1801123 C/- carriers (N= 105) achieved significantly worse OS compared to T/T (N = 464) in univariate (HR = 1.32 [95%CI 1.03-1.70], p = 0.029) and in multivariable. Similar results were observed among RAS wild type. Patients with IGF1 rs2946834 T/- variant (N= 280) achieved improved PFS compared to C/C (N = 257) in univariate (HR = 0.77 [95%CI 0.64-0.92], p = 0.004) and in multivariable. In the RAS wild-type subgroup IGF1 rs2946834 T/- carriers showed better PFS and OS compared to C/C (univariate HR for PFS = 0.65 [95%CI 0.51-0.81], p < 0.001; multivariable HR for PFS = 0.63 [95%CI 0.50-0.81], p < 0.001). IRS1 rs1801123 SNP was identified as a new prognostic marker for mCRC. IGF1 rs2946834 was confirmed as prognostic factor in the overall population and in RAS wild type patients. Our findings underline the importance of IGF downstream signaling pathway in RAS wild-type mCRC patient.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Proteínas Substratos do Receptor de Insulina/genética , Polimorfismo de Nucleotídeo Único , Somatomedinas/genética , Bevacizumab/uso terapêutico , Camptotecina/análogos & derivados , Camptotecina/uso terapêutico , Cetuximab/uso terapêutico , Neoplasias Colorretais/genética , Feminino , Fluoruracila/uso terapêutico , Estudos de Associação Genética/métodos , Humanos , Leucovorina/uso terapêutico , Masculino , Metástase Neoplásica , Prognóstico , Análise de Sequência de DNA , Transdução de Sinais , Análise de SobrevidaRESUMO
The interactive and cumulative impacts of climate change on natural resources such as coral reefs present numerous challenges for conservation planning and management. Climate change adaptation is complex due to climate-stressor interactions across multiple spatial and temporal scales. This leaves decision makers worldwide faced with local, regional, and global-scale threats to ecosystem processes and services, occurring over time frames that require both near-term and long-term planning. Thus there is a need for structured approaches to adaptation planning that integrate existing methods for vulnerability assessment with design and evaluation of effective adaptation responses. The Corals and Climate Adaptation Planning project of the U.S. Coral Reef Task Force seeks to develop guidance for improving coral reef management through tailored application of a climate-smart approach. This approach is based on principles from a recently-published guide which provides a framework for adopting forward-looking goals, based on assessing vulnerabilities to climate change and applying a structured process to design effective adaptation strategies. Work presented in this paper includes: (1) examination of the climate-smart management cycle as it relates to coral reefs; (2) a compilation of adaptation strategies for coral reefs drawn from a comprehensive review of the literature; (3) in-depth demonstration of climate-smart design for place-based crafting of robust adaptation actions; and (4) feedback from stakeholders on the perceived usefulness of the approach. We conclude with a discussion of lessons-learned on integrating climate-smart design into real-world management planning processes and a call from stakeholders for an "adaptation design tool" that is now under development.
Assuntos
Antozoários/crescimento & desenvolvimento , Mudança Climática , Conservação dos Recursos Naturais/métodos , Recifes de Corais , Ecossistema , Animais , Clima , Tomada de Decisões , Formulação de Políticas , Estados UnidosRESUMO
BACKGROUND: The incidence of thyroid cancer in the United States has risen dramatically since the 1970s, driven by an increase in the diagnosis of small tumors. There is a paucity of published New Mexico (NM) specific data regarding thyroid cancer. We hypothesized that due to New Mexico's unique geographic and cultural makeup, the incidence of thyroid cancer and tumor size at diagnosis in this state would differ from that demonstrated on a national level. METHODS: The New Mexico Tumor Registry (NMTR) was queried to include all NM residents diagnosed with thyroid cancer between 1992 and 2019. For 2010 to 2019, age-adjusted incidence rates were calculated via direct method using the 2000 United States population as the adjustment standard. Differences in incidence rate and tumor size by race/ethnicity and residence (metropolitan vs non-metropolitan) were assessed with rate ratios between groups. For 1992 to 2019, temporal trends in age-adjusted incidence rates for major race/ethnic groups in NM [Non-Hispanic White (NHW), Hispanic, and American Indian (AI)] were assessed by joinpoint regression using National Cancer Institute software. RESULTS: Our study included 3,161 patients for the time period 2010 to 2019, including NHW (1518), Hispanic (1425), and AI (218) cases. The overall incidence rates for NM AIs were lower than those for Hispanics and NHWs because of a decreased incidence of very small tumors (<1.1 cm). The incidence rates for large tumors (>5.1 cm) was equivalent among groups. In the early 2000s, Hispanics also had lower rates of small tumors when compared to NHWs but this trend disappeared over time. CONCLUSION: AIs in New Mexico have been left out of the nationwide increase in incidental diagnosis of small thyroid tumors. This same pattern was noted for Hispanics in the early 2000s but changed over time to mirror incidence rates for NHWs. These data are illustrative of the health care disparities that exist among New Mexico's population and how these disparities have changed over time.
Assuntos
Hispânico ou Latino , Neoplasias da Glândula Tireoide , População Branca , Humanos , Neoplasias da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/etnologia , Neoplasias da Glândula Tireoide/patologia , Incidência , New Mexico/epidemiologia , Masculino , Hispânico ou Latino/estatística & dados numéricos , Feminino , Pessoa de Meia-Idade , Adulto , População Branca/estatística & dados numéricos , Idoso , Sistema de Registros , Indígenas Norte-Americanos/estatística & dados numéricos , Carga TumoralRESUMO
Changing environmental conditions are forcing natural resource managers and communities to adapt their strategies to account for global shifts in precipitation, temperature, sea level and more, all of which are occurring in addition to local human impacts. Adapting to threats from climate change requires a fundamental shift in the practice of natural resource management through the development of forward-looking "climate-smart" goals and strategies. Here we present a proof-of-concept application of a decision-support tool to help design climate-smart management actions for the watershed and coral reef management plan for Guánica Bay watershed in southwest Puerto Rico. We also explore the connection between adaptation planning and coral reef resilience, using a recently developed Puerto Rico-wide reef resilience assessment. In the first phase of the study, we used the publicly available Adaptation Design Tool to draft initial climate-smart versions of twelve proposed management actions. In the second phase, two actions (dirt road management on steep slopes, and coral reef restoration) were further refined through consultations with local experts to make more detailed design adjustments; this included the option to use information from the coral reef resilience assessment to inform design improvements. The first phase resulted in moderately detailed assessments that broadly accounted for anticipated direct and indirect effects of climate change on the planned management actions. The second phase resulted in more site-specific technical assessments and additional important design details. The expert panel charged with discussing climate-smart reef restoration around Guánica used the reef resilience assessment to guide discussion of reef restoration, highlighting the importance of having such information available for adaptation planning. This study demonstrates how climate change impacts can be effectively incorporated into a management plan at the most granular level of planning and how a structured, formalized process can be as valuable as the resulting adaptation information.
Assuntos
Aclimatação , Antozoários/fisiologia , Mudança Climática , Conservação dos Recursos Naturais , Recifes de Corais , Animais , Porto RicoRESUMO
Public lands and waters in the United States traditionally have been managed using frameworks and objectives that were established under an implicit assumption of stable climatic conditions. However, projected climatic changes render this assumption invalid. Here, we summarize general principles for management adaptations that have emerged from a major literature review. These general principles cover many topics including: (1) how to assess climate impacts to ecosystem processes that are key to management goals; (2) using management practices to support ecosystem resilience; (3) converting barriers that may inhibit management responses into opportunities for successful implementation; and (4) promoting flexible decision making that takes into account challenges of scale and thresholds. To date, the literature on management adaptations to climate change has mostly focused on strategies for bolstering the resilience of ecosystems to persist in their current states. Yet in the longer term, it is anticipated that climate change will push certain ecosystems and species beyond their capacity to recover. When managing to support resilience becomes infeasible, adaptation may require more than simply changing management practices--it may require changing management goals and managing transitions to new ecosystem states. After transitions have occurred, management will again support resilience--this time for a new ecosystem state. Thus, successful management of natural resources in the context of climate change will require recognition on the part of managers and decisions makers of the need to cycle between "managing for resilience" and "managing for change."
Assuntos
Mudança Climática , Conservação dos Recursos Naturais , Tomada de Decisões , Meio Ambiente , Monitoramento Ambiental , Estados UnidosRESUMO
Globally increasing sea surface temperatures threaten coral reefs, both directly and through interactions with local stressors. More resilient reefs have a higher likelihood of returning to a coral-dominated state following a disturbance, such as a mass bleaching event. To advance practical approaches to reef resilience assessments and aid resilience-based management of coral reefs, we conducted a resilience assessment for Puerto Rico's coral reefs, modified from methods used in other U.S. jurisdictions. We calculated relative resilience scores for 103 sites from an existing commonwealth-wide survey using eight resilience indicators-such as coral diversity, macroalgae percent cover, and herbivorous fish biomass-and assessed which indicators most drove resilience. We found that sites of very different relative resilience were generally highly spatially intermixed, underscoring the importance and necessity of decision making and management at fine scales. In combination with information on levels of two localized stressors (fishing pressure and pollution exposure), we used the resilience indicators to assess which of seven potential management actions could be used at each site to maintain or improve resilience. Fishery management was the management action that applied to the most sites. Furthermore, we combined sites' resilience scores with projected ocean warming to assign sites to vulnerability categories. Island-wide or community-level managers can use the actions and vulnerability information as a starting point for resilience-based management of their reefs. This assessment differs from many previous ones because we tested how much information could be yielded by a "desktop" assessment using freely-available, existing data rather than from a customized, resilience-focused field survey. The available data still permitted analyses comparable to previous assessments, demonstrating that desktop resilience assessments can substitute for assessments with field components under some circumstances.
Assuntos
Mudança Climática , Recifes de Corais , Monitorização de Parâmetros Ecológicos/métodos , Recuperação e Remediação Ambiental , Animais , Porto RicoRESUMO
BACKGROUND: Macrophages play a crucial role in the interaction between tumor and immune system, and iNOS is known as a surrogate marker of M1 macrophages activation. The goal of the study was to investigate the role of iNOS polymorphisms as prognostic marker in mCRC patients. MATERIALS AND METHODS: Functional significant polymorphisms in the promoter of INOS gene were analyzed by PCR-based and direct DNA sequencing in 4 cohorts of patients receiving bevacizumab based first-line chemotherapy: two evaluation cohorts (TRIBE ARM A and ARM B) and two validation cohorts (FIRE 3 arm A and MOMA). The relation of the SNPs with PFS and OS was evaluated through Kaplan-Meier method and log-rank test. Subgroup analyses according to RAS status were preplanned. RESULTS: In the exploratory cohort 1 (TRIBE A), patients with CCTTT any>13repeats (N = 57) showed improved median PFS compared with patients carrying the ≤13/≤13 repeats variant (N = 152) (HR, 0.64; 95%CI 0.44-0.92, p = 0.010). Similar results were shown adopting the >26repeats/≤26 repeats (HR, 0.56; 95%CI 0.36-0.87, p = 0.005). In RAS mutant, patient with any>13 repeats (N = 24) had improved PFS results compared with those carrying the ≤13/≤13 repeats variant (N = 81) (HR, 0.51; 95%CI 0.30-0.87, p = 30.009). Similar results were found adopting the >26 repeats/≤26 repeats cut off: (HR, 0.52; 95%CI 0.27-0.98, p = 0.035). These data were partially confirmed in the exploratory cohort 2 (TRIBE B): a better median PFS was observed in patients with >26 repeats vs ≤26 repeats (N = 205) patients. However, these data were not confirmed in the two validation cohorts. CONCLUSION: We failed to replicate the exploratory findings in both validation sets. The CCTTT polymorphic region of the INOS gene does not predict outcome in mCRC receiving bevacizumab based first line chemotherapy. Further investigations are needed to reveal mechanisms between tumor, immune system and chemotherapy response.
Assuntos
Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Óxido Nítrico Sintase Tipo II/genética , Polimorfismo de Nucleotídeo Único , Idoso , Bevacizumab/farmacologia , Bevacizumab/uso terapêutico , Ensaios Clínicos como Assunto , Estudos de Coortes , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/tratamento farmacológico , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Prognóstico , Resultado do TratamentoRESUMO
The purpose of this study was to evaluate the clinical significance of single-nucleotide polymorphisms in TLR1, TLR2, TLR6, and TAK1 in patients with metastatic colorectal cancer (mCRC). We genotyped 9 SNPs of TLR1, TLR2, TLR6, and TAK1 in mCRC patients treated with first-line FOLFIRI (combination therapy of irinotecan, 5-fluorouracil, and folinic acid) plus bevacizumab, using a discovery cohort (TRIBE trial, n = 228) and a validation cohort (FIRE-3 trial, n = 297), and analyzed for the association with response rate (RR), progression-free survival (PFS), and overall survival (OS). There was a significant association of TLR1 rs5743618 (T1805G) with the clinical outcome. In the TRIBE cohort, a homozygous wild-type genotype (T/T) associated with a significantly lower RR compared with variant T/G and G/G genotypes (43% vs. 62%, P = 0.025), and this observation was validated in the FIRE-3 cohort (46% vs. 65%, P = 0.021). In addition, those patients with the T/T genotype had significantly worse PFS (median, 8.2 vs. 10.5 months; HR, 1.57; 95% CI, 1.09-2.28, P = 0.014) and OS (median: 19.9 vs. 27.9 months; HR, 1.63; 95% CI, 1.14-2.35, P = 0.007), compared with those with other genotypes in the TRIBE cohort. These differences remained statistically significant in multivariate analysis. Our data suggest that TLR1 rs5743618 could serve as a predictor of clinical response to FOLFIRI plus bevacizumab in patients with mCRC. Mol Cancer Ther; 15(7); 1740-5. ©2016 AACR.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Camptotecina/análogos & derivados , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Polimorfismo de Nucleotídeo Único , Receptor 1 Toll-Like/genética , Idoso , Idoso de 80 Anos ou mais , Alelos , Bevacizumab/administração & dosagem , Camptotecina/uso terapêutico , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Feminino , Fluoruracila/uso terapêutico , Genes ras , Genótipo , Humanos , Leucovorina/uso terapêutico , Masculino , Pessoa de Meia-Idade , Mutação , Metástase Neoplásica , Estadiamento de Neoplasias , Retratamento , Resultado do TratamentoRESUMO
(1) A recirculating isolated superfused skeletal muscle preparation has been developed for the study of rat soleus muscles at physiological temperature using 31P Nuclear Magnetic Resonance (NMR). (2) This system has been used to study intracellular muscle high energy phosphate content and pH during experimental damage to the muscle induced by 2,4-dinitrophenol, deoxycholate and the calcium ionophore, A23187. (3) Results indicate that release of intracellular cytosolic enzymes from damaged skeletal muscle may be induced by phosphocreatine (PCr) and adenosine trisphosphate (ATP) depletion, but under certain circumstances intracellular enzymes can be released from skeletal muscle without any fall in muscle PCr or ATP content.
Assuntos
Citosol/enzimologia , Metabolismo Energético , Músculos/enzimologia , 2,4-Dinitrofenol , Trifosfato de Adenosina/farmacologia , Animais , Calcimicina/farmacologia , Creatina Quinase/metabolismo , Citosol/efeitos dos fármacos , Ácido Desoxicólico/farmacologia , Dinitrofenóis/farmacologia , Metabolismo Energético/efeitos dos fármacos , Feminino , Espectroscopia de Ressonância Magnética , Músculos/efeitos dos fármacos , Fosfocreatina/farmacologia , Ratos , Ratos EndogâmicosRESUMO
Creatine kinase (CK) release in response to excessive electrically stimulated contractile activity has been studied in isolated rat soleus muscles. The exacerbation of CK release induced by contractile activity was found to be directly related to the length of time for which the muscle was stimulated and indirectly related to the recovery of force following the end of stimulation. 31P-NMR studies were undertaken using a recirculating superfused muscle preparation and demonstrated that muscles subjected to two different stimulation protocols (stimulation for 0.5 s every 2 s in oxygenated medium or for 1.5 s every 2 s in anoxic medium) had similar falls in ATP content and pH despite a substantially greater release of CK from the muscles stimulated under anoxia. However, stimulated muscles under anoxia showed a more rapid fall and reduced recovery of phosphocreatine and a greater sustained elevation of inorganic phosphate than muscles in oxygenated medium. It is concluded that only part of the increased loss of CK from muscles stimulated in anoxic medium can be explained by release from cells which have lost energy supplies and therefore that other mechanisms must exist which allow release of CK and other cytosolic enzymes from muscle cells.
Assuntos
Metabolismo Energético , Espectroscopia de Ressonância Magnética , Contração Muscular/fisiologia , Músculos/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Creatina Quinase/metabolismo , Estimulação Elétrica , Feminino , Glicogênio/metabolismo , Concentração de Íons de Hidrogênio , Lactatos/metabolismo , Ácido Láctico , Fosfatos/metabolismo , Fosfocreatina/metabolismo , Ratos , Ratos EndogâmicosRESUMO
The biochemical, histological and ultrastructural effects of 2,4-dinitrophenol and the calcium ionophore, A23187, on rat soleus muscle incubated in vitro have been examined to test the hypothesis that immunohistochemical techniques can be used to recognize early structural features of fibre damage. In control muscles, despite mild glycogen depletion and a mild reduction in protein synthetic rate in the central portion of the muscle, fibres throughout the muscle appear to be viable with normal cytoskeletal and contractile protein architecture, normal concentrations of high energy phosphates and no creatine kinase efflux. Dinitrophenol causes rapid creatine kinase efflux, extensive loss of immunolabelling for desmin and dystrophin, and abnormal myosin immunolabelling. Creatine kinase efflux and the changes in desmin and dystrophin are reduced by the exclusion of calcium. A23187 causes more gradual creatine kinase efflux associated with changes in myosin immunolabelling, but loss of desmin and dystrophin immunolabelling is restricted to a few of the most peripheral fibres. The results suggest that immunohistochemical methods can be used to reveal differences in the intracellular mechanisms of muscle damage. Although both dinitrophenol and A23187 may act, in part, through calcium-mediated processes, their effects on cytoskeletal proteins differ. Creatine kinase efflux after A23187 may not be due to gross sarcolemmal damage.
Assuntos
Calcimicina/farmacologia , Dinitrofenóis/farmacologia , Músculo Esquelético/metabolismo , 2,4-Dinitrofenol , Animais , Creatina Quinase/metabolismo , Técnicas de Cultura , Desmina/metabolismo , Distrofina/metabolismo , Feminino , Técnicas Imunoenzimáticas , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/ultraestrutura , Miosinas/metabolismo , Ratos , Ratos WistarRESUMO
The 31P-NMR technique has been used to assess the intracellular ratios and concentrations of mobile ATP and ADP and the intracellular pH in an insulin-secreting cell line, RINm5F. The single-channel current-recording technique has been used to investigate the effects of changes in the concentrations of ATP and ADP on the gating of nucleotide-dependent K+ channels. Adding ATP to the membrane inside closes these channels. However, in the continued presence of ATP adding ADP invariably leads to the reactivation of ATP-inhibited K+ channels, even at ATP4-/ADP3- concentration ratios greater than 7:1. Interactions between ATP4- and ADP3- seem competitive. An increase in the concentration ratio ATP4-/ADP3- consistently evoked a decrease in the open-state probability of K+ channels; conversely, a decrease in ATP4-/ADP3- increased the frequency of K+ channel opening events. Channel gating was also influenced by changes in the absolute concentrations of ATP4- and ADP3-, at constant free concentration ratios. ADP-evoked stimulation of ATP-inhibited channels did not result from phosphorylation of the channel, as ADP-beta-S, a nonhydrolyzable analog of ADP, not only stimulated but enhanced ADP-induced activation of K+ channels, in the presence of ATP. Similarly, ADP was able to activate K+ channels in the presence of two nonhydrolyzable derivatives of ATP, AMP-PNP and beta gamma methylene ATP.
Assuntos
Difosfato de Adenosina/fisiologia , Trifosfato de Adenosina/fisiologia , Insulina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Nucleotídeos/farmacologia , Canais de Potássio/metabolismo , Difosfato de Adenosina/análogos & derivados , Difosfato de Adenosina/farmacologia , Trifosfato de Adenosina/análogos & derivados , Linhagem Celular , Gliceraldeído/farmacologia , Concentração de Íons de Hidrogênio , Secreção de Insulina , Ilhotas Pancreáticas/análise , Ilhotas Pancreáticas/ultraestrutura , Espectroscopia de Ressonância Magnética/métodos , Potenciais da Membrana/efeitos dos fármacos , Nucleotídeos/análise , Fosforilação , Canais de Potássio/efeitos dos fármacos , Canais de Potássio/ultraestrutura , Tionucleotídeos/farmacologiaRESUMO
We describe the use of 31P NMR spectroscopy in the study of metabolic changes related to hypoxia in cultured human tumor cells in vitro. The 31P NMR spectrum can easily distinguish between metabolically active cells, metabolically inactive "dormant" cells, and necrotic cells. A crucial observation was that of the ability of the "dormant" cells to resume active metabolism on incubation with oxygen after long periods of hypoxia.