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1.
Cancer Epidemiol Biomarkers Prev ; 32(11): 1608-1616, 2023 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-37566431

RESUMO

BACKGROUND: Mailed fecal immunochemical test (FIT) outreach can improve colorectal cancer screening rates, yet little is known about how to optimize these programs for effectiveness and cost. METHODS: PROMPT was a pragmatic, stepped-wedge, cluster-randomized effectiveness trial of mailed FIT outreach. Participants in the standard condition were mailed a FIT and received live telephone reminders to return it. Participants in the enhanced condition also received a tailored advance notification (text message or live phone call) and two automated phone call reminders. The primary outcome was 6-month FIT completion; secondary outcomes were any colorectal cancer screening completion at 6 months, implementation, and program costs. RESULTS: The study included 27,585 participants (80% ages 50-64, 82% Hispanic/Latino; 68% preferred Spanish). A higher proportion of enhanced participants completed FIT at 6 months than standard participants, both in intention-to-treat [+2.8%, 95% confidence interval (CI; 0.4-5.2)] and per-protocol [limited to individuals who were reached; +16.9%, 95% CI (12.3-20.3)] analyses. Text messages and automated calls were successfully delivered to 91% to 100% of participants. The per-patient cost for standard mailed FIT was $10.84. The enhanced program's text message plus automated call reminder cost an additional $0.66; live phone calls plus an automated call reminder cost an additional $10.82 per patient. CONCLUSIONS: Adding advance notifications and automated calls to a standard mailed FIT program boosted 6-month FIT completion rates at a small additional per-patient cost. IMPACT: Enhancements to mailed FIT outreach can improve colorectal cancer screening participation. Future research might test the addition of educational video messaging for screening-naïve adults.


Assuntos
Neoplasias Colorretais , Detecção Precoce de Câncer , Humanos , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/prevenção & controle , Detecção Precoce de Câncer/métodos , Programas de Rastreamento/métodos , Sangue Oculto , Sistemas de Alerta , Telefone , Pessoa de Meia-Idade
2.
J Prim Care Community Health ; 13: 21501319221138423, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36448466

RESUMO

OBJECTIVE: Individuals with an abnormal fecal immunochemical test (FIT) result have an elevated risk of colorectal cancer, and the risk increases if the follow-up colonoscopy is delayed. Of note, rates of follow-up colonoscopy are alarmingly low in federally qualified health centers (FQHCs), US health care settings that serve a majority racial and ethnic minority patient population. We assessed factors associated with colonoscopy after an abnormal FIT result and used chart-abstracted data to assess reasons (including process measures) for lack of follow-up as part of an annual, mailed-FIT outreach program within a large, Latino-serving FQHC. METHODS: As part of the National Institutes of Health-funded PROMPT study, we identified patients with an abnormal FIT result and used logistic regression to assess associations between patient demographics and receipt of follow-up colonoscopy, controlling for patients' preferred language. We report on time (days) to referral and time to colonoscopy. For charts with an abnormal FIT result but no evidence of colonoscopy, we performed a manual abstraction and obtained the reason for the absence of colonoscopy. When there was no evidence of colonoscopy in a patient's electronic health record (EHR), we performed an automated query of the administrative claims database to identify colonoscopy outcomes. RESULTS: We identified 324 patients with abnormal FIT results from July to October 2018. These patients were mostly publicly insured (Medicaid 53.1%, Medicare 14.5%), 81.8% were aged 50 to 64 years, 55.3% were female, 80.3% were Hispanic/Latino, and 67.3% preferred to speak Spanish. We found that 108/324 (33.3%) patients completed colonoscopy within 12 months, and the median time to colonoscopy was 94 days (IQR: 68-176). Common barriers to colonoscopy completion, obtained from chart-abstracted data, were: no documentation following referral to gastrointestinal (GI) specialist or GI consultation (41.6%), no referral to GI specialist following abnormal fecal test (34.2%), and absence of a valid insurance authorization (6.5%). CONCLUSIONS: Multi-level strategies are needed to provide optimal care across the cancer continuum for FQHC patients. In order to reduce the risk of CRC and realize the return on fecal testing investment, concerted system-level efforts are urgently needed to improve rates of follow-up colonoscopy among FQHC patients and redress racial and ethnic disparities in CRC screening outcomes.


Assuntos
Neoplasias Colorretais , Detecção Precoce de Câncer , Estados Unidos , Humanos , Idoso , Feminino , Masculino , Etnicidade , Grupos Minoritários , Medicare , Colonoscopia , Neoplasias Colorretais/diagnóstico
3.
Perm J ; 26(3): 74-82, 2022 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-36038966

RESUMO

BackgroundThe Diabetes Prevention Program (DPP) has been translated into digital formats. We report an economic evaluation of a digital DPP implemented in a large, integrated health care system. MethodsPatients (n = 4148) were invited to participate in digital DPP based on clinical characteristics (HbA1c 5.7%-6.4% and body mass index ≥ 30 kg/m2) assessed using electronic medical record data. Using a propensity score we matched (1:1) enrolled and not enrolled patients for a total of 784. We identified high-risk patients (ie, above the 50th percentile of risk; n = 202) by calculating each patient's 2-year of developing diabetes. We report the cost of the intervention and the costs of medical care over 12- and 24-month follow-up, and the incremental cost-effectiveness ratio as the cost per additional kilogram weight loss at 24 months. ResultsAt 12 months, enrolled patients had lower total costs ($6,926, 95% CI $5,681-$8,171) than not enrolled patients ($7,538, 95% CI $6,293-$8,783). This pattern attenuated slightly at 24 months (enrolled = $16,255, 95% CI $14,097-$18,412; not enrolled = $16,688, 95% CI $14,531-$18,846). We found an incremental cost-effectiveness ratio of $81.92 per additional kilogram weight loss. For high-risk patients, the digital DPP group had, on average, lower costs and greater weight loss. We found a 55% chance of the digital DPP program being cost-effective at a willingness-to-pay of $150 per additional kilogram of weight loss; at the same willingness-to-pay, there is a 60% chance in the high-risk subgroup. Limitations include the nonrandomized design and potential volunteer bias. ConclusionDigital DPP had a favorable cost-effectiveness profile compared to other lifestyle interventions.


Assuntos
Prestação Integrada de Cuidados de Saúde , Diabetes Mellitus Tipo 2 , Análise Custo-Benefício , Diabetes Mellitus Tipo 2/prevenção & controle , Hemoglobinas Glicadas , Humanos , Redução de Peso
4.
Environ Adv ; 82022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35992224

RESUMO

Environmental pollution is a global concern because of its associated risks to human health and ecosystem. The bio-monitoring of environmental health has attracted much attention in recent years and efforts to minimize environmental contamination as well as to delineate toxicological mechanisms related to toxic exposure are essential to improve the health conditions of both humans and animals. This review aims to substantiate the need and advantages in utilizing cockroaches as a complementary, non-mammalian model to further understand the noxious impact of environmental contaminants on humans and animals. We discuss recent advances in neurotoxicology, immunotoxicology, reproductive and developmental toxicology, environmental forensic entomotoxicology, and environmental toxicology that corroborate the utility of the cockroach (Periplaneta americana, Blaptica dubia, Blattella germanica and Nauphoeta cinerea) in addressing toxicological mechanisms as well as a sensor of environmental pollution. Indeed, recent improvements in behavioural assessment and the detection of potential biomarkers allow for the recognition of phenotypic alterations in cockroaches following exposure to toxic chemicals namely saxitoxin, methylmercury, polychlorinated biphenyls, electromagnetic fields, pharmaceuticals, polycyclic aromatic hydrocarbon, chemical warfare agents and nanoparticles. The review provides a state-of-the-art update on the current utility of cockroach models in various aspects of toxicology as well as discusses the potential limitations and future perspectives.

5.
Artigo em Inglês | MEDLINE | ID: mdl-35618149

RESUMO

Pathological anxiety is a set of diseases characterized by specific clinical manifestations and the use of alternative models may provide novel insights in translational neurobehavioral research. In zebrafish, the separate performance of novel tank and light dark tests in different order to assess anxiety using a same animal may provide conflicting data due to the battery effect and/or time-drug-response and variability across tests. To improve data reliability, we aimed to characterize a novel behavioral paradigm to measure geotaxis and scototaxis as anxiety-like responses in the same trial. The novel apparatus consisted of four colored-compartments, with specific white- and black sections delimited in both bottom and upper areas of the tank. The main baseline responses of zebrafish in the novel apparatus were measured and animals were further exposed to modulators of anxiety. Zebrafish showed robust habituation to novelty stress during the 6-min trial with preference for the black section while exploring the top area. Fluoxetine (100 µg/L, 15 min) reduced geotaxis and scototaxis and ketamine (20 mg/L, 20 min) decreased geotaxis and increased the distance traveled in the black section while exploring the top, possibly due to the increased circling behavior. As anxiogenic modulators, conspecific alarm substance (3.5 mL/L, 5 min) exacerbated risk assessment, geotaxis, and scototaxis, whereas caffeine (10 mg/L, 15 min) increased geotaxis and exploration in the black section of the top area. Since important correlations were also found for relevant anxiety-like behaviors, our findings support the predictive validity of this novel paradigm to simultaneously assess geotaxis and scototaxis in zebrafish. Moreover, it fully adheres to the 3Rs principle of animal experimentation of reducing the number of subjects tested, execution time, also minimizing a potential battery effect.


Assuntos
Comportamento Animal , Peixe-Zebra , Animais , Ansiedade , Humanos , Atividade Motora , Reprodutibilidade dos Testes , Peixe-Zebra/fisiologia
6.
J Environ Manage ; 314: 114994, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35452885

RESUMO

Evidence-informed decision-making is in increasing demand given growing pressures on marine environments. A way to facilitate this is by knowledge exchange among marine scientists and decision-makers. While many barriers are reported in the literature, there are also examples whereby research has successfully informed marine decision-making (i.e., 'bright-spots'). Here, we identify and analyze 25 bright-spots from a wide range of marine fields, contexts, and locations to provide insights into how to improve knowledge exchange at the interface of marine science and policy. Through qualitative surveys we investigate what initiated the bright-spots, their goals, and approaches to knowledge exchange. We also seek to identify what outcomes/impacts have been achieved, the enablers of success, and what lessons can be learnt to guide future knowledge exchange efforts. Results show that a diversity of approaches were used for knowledge exchange, from consultative engagement to genuine knowledge co-production. We show that diverse successes at the interface of marine science and policy are achievable and include impacts on policy, people, and governance. Such successes were enabled by factors related to the actors, processes, support, context, and timing. For example, the importance of involving diverse actors and managing positive relationships is a key lesson for success. However, enabling routine success will require: 1) transforming the ways in which we train scientists to include a greater focus on interpersonal skills, 2) institutionalizing and supporting knowledge exchange activities in organizational agendas, 3) conceptualizing and implementing broader research impact metrics, and 4) transforming funding mechanisms to focus on need-based interventions, impact planning, and an acknowledgement of the required time and effort that underpin knowledge exchange activities.


Assuntos
Tomada de Decisões , Conhecimento , Política de Saúde , Humanos , Aprendizagem , Organizações , Políticas
7.
J Comput Aided Mol Des ; 34(11): 1157-1169, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32648151

RESUMO

Experimental 3D structures of calcium channels with phenylalkylamines (PAAs) provide basis for further analysis of atomic mechanisms of these important cardiovascular drugs. In the crystal structure of the engineered calcium channel CavAb with Br-verapamil and in the cryo-EM structure of the Cav1.1 channel with verapamil, the ligands bind in the inner pore. However, there are significant differences between these structures. In the crystal structure the ligand ammonium group is much closer to the ion in the selectivity-filter region Site 3, which is most proximal to the inner pore, than in the cryo-EM structure. Here we used Monte Carlo energy minimizations to dock PAAs in calcium channels. Our computations suggest that in the crystal structure Site 3 is occupied by a water molecule rather than by a calcium ion. Analysis of the published electron density map does not rule out this possibility. In the cryo-EM structures the ammonium group of verapamil is shifted from the calcium ion in Site 3 either along the pore axis, towards the cytoplasm or away from the axis. Our unbiased docking reproduced these binding modes. However, in the cryo-EM structures detergent and lipid molecules interact with verapamil. When we removed these molecules, the nitrile group of verapamil bound to the calcium ion in Site 3. Models of Cav1.2 with different PAAs suggest similar binding modes and direct contacts of the ligands electronegative atoms with the calcium ion in Site 3. Such interactions explain paradoxes in structure-activity relationships of PAAs.


Assuntos
Bloqueadores dos Canais de Cálcio/química , Canais de Cálcio/metabolismo , Verapamil/química , Sequência de Aminoácidos , Sítios de Ligação , Cálcio/química , Cristalização , Ligantes , Simulação de Acoplamento Molecular , Método de Monte Carlo , Relação Estrutura-Atividade
8.
Circ Res ; 124(4): 491-497, 2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-31031412

RESUMO

As we commemorate the 70th Anniversary of the National Heart, Lung, and Blood Institute (NHLBI) and celebrate important milestones that have been achieved by the Division of Cardiovascular Sciences (DCVS), it is imperative that DCVS and the Extramural Research community at-large continue to address critical public health challenges that persist within the area of Cardiovascular Diseases (CVD). The NHLBI's Strategic Vision, developed with extensive input from the extramural research community and published in 2016, included overarching goals and strategic objectives that serve to provide a general blueprint for sustaining the legacy of the Institute by leveraging opportunities in emerging scientific areas (e.g., regenerative medicine, omics technology, data science, precision medicine, and mobile health), finding new ways to address enduring challenges (e.g., social determinants of health, health inequities, prevention, and health promotion), and training the next generation of heart, lung, blood, and sleep researchers. DCVS has developed a strategic vision implementation plan to provide a cardiovascular framing for the pursuit of the Institute's overarching goals and strategic objectives garnered from the input of the broader NHLBI community. This plan highlights six scientific focus areas that demonstrate a cross-cutting and multifaceted approach to addressing cardiovascular sciences, including 1) addressing social determinants of cardiovascular health (CVH) and health inequities, 2) enhancing resilience, 3) promoting CVH and preventing CVD Across the lifespan, 4) eliminating hypertension-related CVD, 5) reducing the burden of heart failure, and 6) preventing vascular dementia. These priorities will guide our efforts in Institute-driven activities in the coming years but will not exclude development of other novel ideas or the support of investigator-initiated grant awards. The DCVS Strategic Vision implementation plan is a living document that will evolve with iterative dialogue with the NHLBI community and adapt as the dynamic scientific landscape changes to seize emerging opportunities.


Assuntos
Cardiologia/normas , Doenças Cardiovasculares/terapia , National Heart, Lung, and Blood Institute (U.S.) , Guias de Prática Clínica como Assunto , Cardiologia/economia , Cardiologia/tendências , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/etiologia , Humanos , Estados Unidos
9.
J Am Soc Echocardiogr ; 26(4): 325-38, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23537771
12.
Rev Med Brux ; 32(1): 10-3, 2011.
Artigo em Francês | MEDLINE | ID: mdl-21485458

RESUMO

We have analyzed the relationship between the prevalence of diabetes mellitus (type 2) and socio-economic status of patients. The cross-sectional study included 79,855 patients registered in Belgium capitation-fee primary health care centers. The adjusted prevalence for age and gender was 6.3%, significantly higher than the estimated 4.7% in the general population. The gap is mainly explained by the lower socio-economic status of the patients we take care of. Inside our population we found a 1.8 times higher risk to be affected by diabetes mellitus for patients with lower socio-economic status (95% confidence interval: 1.6-1.9). This higher risk is found for all age groups except for the elderly. Studies should be designed to investigate how that social inequality for health also concern quality of care and therapeutical outcomes.


Assuntos
Diabetes Mellitus Tipo 2/epidemiologia , Classe Social , Idoso , Bélgica/epidemiologia , Estudos Transversais , Diabetes Mellitus Tipo 2/economia , Feminino , Humanos , Masculino , Prevalência , Atenção Primária à Saúde
13.
Endoscopy ; 43(2): 81-6, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21108174

RESUMO

BACKGROUND AND STUDY AIMS: Pathological examination of colorectal polyps is useful if clinical management is affected (i. e. when invasive carcinoma is detected or postpolypectomy surveillance interval is guided). Our aim was to assess whether the pathological examination of some diminutive (measuring ≤ 5 mm) polyps can be omitted. PATIENTS AND METHODS: Consecutive patients undergoing a colonoscopy at Pasteur Hospital (Colmar, France) between January and August 2008 were included in this prospective study. Six senior gastroenterologists predicted the future surveillance interval without referring to the result of pathological examination. RESULTS: In all, 350 polyps from 175 patients were removed and analyzed. The endoscopist was able to predict the correct surveillance interval without referring to the result of pathological examination in 118 patients (67.4 %; 95 % confidence interval [CI] 60.5 - 74.4). The pathological examination of 18.4 % (95 % CI 13.7 - 23.1) of diminutive polyps either associated with a cancer or a polyp measuring ≥ 10 mm or removed in very old or frail patients could be omitted without any consequence for the patient. If diminutive polyps one or two in number were discarded without pathological examination in patients with a personal history of colorectal neoplasm, three patients out of 43 would have a 5-year instead of a 3-year surveillance interval. As a whole, if 44.1 % (95 % CI 38.0 - 50.1) of diminutive polyps were discarded, the surveillance interval would remain identical in 98.3 % (95 % CI 96.4 - 100) of patients. CONCLUSIONS: The pathological examination of up to 44 % of diminutive polyps (i. e. 33 % of all polyps), can be safely omitted. The pathological examination would be required only for those with suspicious gross appearance, those three or more in number, and those isolated one or two in number that are removed from people without personal history of colorectal neoplasm.


Assuntos
Adenoma/diagnóstico , Neoplasias do Colo/diagnóstico , Pólipos do Colo/patologia , Árvores de Decisões , Encaminhamento e Consulta , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Distribuição de Qui-Quadrado , Pólipos do Colo/classificação , Pólipos do Colo/economia , Feminino , Humanos , Expectativa de Vida , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Prospectivos , Fatores de Tempo
14.
J Biol Chem ; 284(41): 28332-28342, 2009 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-19700404

RESUMO

Phenylalkylamines (PAAs), a major class of L-type calcium channel (LTCC) blockers, have two aromatic rings connected by a flexible chain with a nitrile substituent. Structural aspects of ligand-channel interactions remain unclear. We have built a KvAP-based model of LTCC and used Monte Carlo energy minimizations to dock devapamil, verapamil, gallopamil, and other PAAs. The PAA-LTCC models have the following common features: (i) the meta-methoxy group in ring A, which is proximal to the nitrile group, accepts an H-bond from a PAA-sensing Tyr_IIIS6; (ii) the meta-methoxy group in ring B accepts an H-bond from a PAA-sensing Tyr_IVS6; (iii) the ammonium group is stabilized at the focus of P-helices; and (iv) the nitrile group binds to a Ca(2+) ion coordinated by the selectivity filter glutamates in repeats III and IV. The latter feature can explain Ca(2+) potentiation of PAA action and the presence of an electronegative atom at a similar position of potent PAA analogs. Tyr substitution of a Thr in IIIS5 is known to enhance action of devapamil and verapamil. Our models predict that the para-methoxy group in ring A of devapamil and verapamil accepts an H-bond from this engineered Tyr. The model explains structure-activity relationships of PAAs, effects of LTCC mutations on PAA potency, data on PAA access to LTCC, and Ca(2+) potentiation of PAA action. Common and class-specific aspects of action of PAAs, dihydropyridines, and benzothiazepines are discussed in view of the repeat interface concept.


Assuntos
Bloqueadores dos Canais de Cálcio , Canais de Cálcio Tipo L/química , Canais de Cálcio Tipo L/metabolismo , Modelos Moleculares , Estrutura Terciária de Proteína , Sequência de Aminoácidos , Sítios de Ligação , Bloqueadores dos Canais de Cálcio/química , Bloqueadores dos Canais de Cálcio/metabolismo , Canais de Cálcio Tipo L/genética , Simulação por Computador , Di-Hidropiridinas/química , Galopamil/química , Galopamil/metabolismo , Dados de Sequência Molecular , Estrutura Molecular , Método de Monte Carlo , Alinhamento de Sequência , Relação Estrutura-Atividade , Verapamil/análogos & derivados , Verapamil/química , Verapamil/metabolismo
15.
J Biol Chem ; 284(28): 19006-17, 2009 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-19416978

RESUMO

1,4-Dihydropyridines (DHPs) constitute a major class of ligands for L-type Ca(2+) channels (LTCC). The DHPs have a boat-like, six-membered ring with an NH group at the stern, an aromatic moiety at the bow, and substituents at the port and starboard sides. Various DHPs exhibit antagonistic or agonistic activities, which were previously explained as stabilization or destabilization, respectively, of the closed activation gate by the portside substituents. Here we report a novel structural model in which agonist and antagonist activities are determined by different parts of the DHP molecule and have different mechanisms. In our model, which is based on Monte Carlo minimizations of DHP-LTCC complexes, the DHP moieties at the stern, bow, and starboard form H-bonds with side chains of the key DHP-sensing residues Tyr_IIIS6, Tyr_IVS6, and Gln_IIIS5, respectively. We propose that these H-bonds, which are common for agonists and antagonists, stabilize the LTCC conformation with the open activation gate. This explains why both agonists and antagonists increase probability of the long lasting channel openings and why even partial disruption of the contacts eliminates the agonistic action. In our model, the portside approaches the selectivity filter. Hydrophobic portside of antagonists may induce long lasting channel closings by destabilizing Ca(2+) binding to the selectivity filter glutamates. Agonists have either hydrophilic substituents or a hydrogen atom at their portside, and thus lack this destabilizing effect. The predicted orientation of the DHP core allows accommodation of long substituents in the domain interface or in the inner pore. Our model may be useful for developing novel clinically relevant LTCC blockers.


Assuntos
Canais de Cálcio Tipo L/química , Cálcio/química , Di-Hidropiridinas/farmacologia , Sequência de Aminoácidos , Sítios de Ligação , Di-Hidropiridinas/química , Ligação de Hidrogênio , Íons , Ligantes , Modelos Químicos , Conformação Molecular , Dados de Sequência Molecular , Método de Monte Carlo , Conformação Proteica , Relação Estrutura-Atividade , Tirosina/química
16.
Mol Pharmacol ; 74(4): 1033-45, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18653802

RESUMO

Local anesthetics (LAs) are known to bind Na+ channels in the closed, open, and inactivated states and reach their binding sites via extracellular and intracellular access pathways. Despite intensive studies, no atomic-scale theory is available to explain the diverse experimental data on the LA actions. Here we attempt to contribute to this theory by simulating access and binding of LAs in the KcsA-based homology model of the closed Na+ channel. We used Monte Carlo minimizations to model the channel with representative local anesthetics N-(2,6-dimethylphenylcarbamoylmethyl)triethylammonium (QX-314), cocaine, and tetracaine. We found the nucleophilic central cavity to be a common binding region for the ammonium group of LAs, whose aromatic group can extend either along the pore axis (vertical binding mode) or to the III/IV domain interface (horizontal binding mode). The vertical mode was earlier predicted for the open channel, but only the horizontal mode is consistent with mutational data on the closed-channel block. To explore hypothetical access pathways of the permanently charged QX-314, we pulled the ligand via the selectivity filter, the closed activation gate, and the III/IV domain interface. Only the last pathway, which leads to the horizontal binding mode, did not impose steric obstacles. The LA ammonium group mobility within the central cavity was more restricted in the vertical mode than in the horizontal mode. Therefore, occupation of the selectivity-filter DEKA locus by a Na+ ion destabilizes the vertical mode, thus favoring the horizontal mode. LA binding in the closed channel requires the resident Na+ ion to leave the nucleophilic central cavity through the selectivity filter, whereas the LA egress should be coupled with reoccupation of the cavity by Na+. This hypothesis on the coupled movement of Na+ and LA in the closed channel explains seemingly contradictory data on how the outer-pore mutations as well as tetrodotoxin and micro-conotoxin binding affect the ingress and egress of LAs.


Assuntos
Anestésicos Locais/metabolismo , Anestésicos Locais/farmacologia , Modelos Biológicos , Canais de Sódio/metabolismo , Anestésicos Locais/química , Sítios de Ligação , Cocaína/química , Cocaína/metabolismo , Cocaína/farmacologia , Simulação por Computador , Conotoxinas/química , Conotoxinas/genética , Lidocaína/análogos & derivados , Lidocaína/química , Lidocaína/metabolismo , Lidocaína/farmacologia , Ligantes , Modelos Moleculares , Estrutura Molecular , Método de Monte Carlo , Mutação , Conformação Proteica , Sódio/química , Canais de Sódio/efeitos dos fármacos , Eletricidade Estática , Tetracaína/química , Tetracaína/metabolismo , Tetracaína/farmacologia , Tetrodotoxina/química , Água/química
17.
Expert Rev Mol Diagn ; 7(2): 149-60, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17331063

RESUMO

Heart, lung and blood diseases exert an enormous toll, accounting for almost half of the deaths in the USA each year. In addition to the morbidity and mortality resulting from these diseases, there is also a high economic burden, estimated at 560 billion US dollars for 2006. Nanotechnology offers a broad range of opportunities to improve diagnosis and therapy for cardiovascular, pulmonary and hematopoietic diseases, thereby decreasing these burdens. This review will focus on four areas of particular promise for the application of nanotechnology: imaging, diagnostics and biosensors, drug delivery and therapy, and tissue engineering and repair. The goal is to summarize the current state of science and technology in these areas and to look at future directions that the field is likely to move in to enhance the diagnosis and treatment of heart, lung and blood diseases.


Assuntos
Cardiopatias/diagnóstico , Doenças Hematológicas/diagnóstico , Pneumopatias/diagnóstico , Nanotecnologia , Animais , Cardiopatias/economia , Cardiopatias/mortalidade , Cardiopatias/terapia , Doenças Hematológicas/economia , Doenças Hematológicas/mortalidade , Doenças Hematológicas/terapia , Humanos , Pneumopatias/economia , Pneumopatias/mortalidade , Pneumopatias/terapia , Nanotecnologia/economia , Nanotecnologia/tendências
18.
Biophys J ; 88(1): 184-97, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15475578

RESUMO

A large body of experimental data on Na+ channels is available, but the interpretation of these data in structural terms is difficult in the absence of a high-resolution structure. Essentially different electrophysiological and pharmacological properties of Na+ and K+ channels and poor identity of their sequences obstruct homology modeling of Na+ channels. In this work, we built the P-loops model of the Na+ channel, in which the pore helices are arranged exactly as in the MthK bacterial K+ channel. The conformation of the selectivity-filter region, which includes residues in positions -2 through +4 from the DEKA locus, was shaped around rigid molecules of saxitoxin and tetrodotoxin that are known to form multiple contacts with this region. Intensive Monte Carlo minimization that started from the MthK-like conformation produced practically identical saxitoxin- and tetrodotoxin-based models. The latter was tested to explain a wide range of experimental data that were not used at the model building stage. The docking of tetrodotoxin analogs unambiguously predicted their optimal orientation and the interaction energy that correlates with the experimental activity. The docking of mu-conotoxin produced a binding model consistent with experimentally known toxin-channel contacts. Monte Carlo-minimized energy profiles of tetramethylammonium pulled through the selectivity-filter region explain the paradoxical experimental data that this organic cation permeates via the DEAA but not the AAAA mutant of the DEKA locus. The model is also consistent with earlier proposed concepts on the Na+ channel selectivity as well as Ca2+ selectivity of the EEEE mutant of the DEKA locus. Thus, the model integrates available experimental data on the Na+ channel P-loops domain, and suggests that it is more similar to K+ channels than was believed before.


Assuntos
Proteínas de Bactérias/química , Canais de Potássio/química , Canais de Sódio/química , Sequência de Aminoácidos , Arginina/química , Cálcio/química , Cátions , Conotoxinas/química , Cristalografia por Raios X , Ligantes , Lisina/química , Modelos Químicos , Modelos Moleculares , Dados de Sequência Molecular , Método de Monte Carlo , Mutação , Peptídeos/química , Potássio/química , Ligação Proteica , Conformação Proteica , Dobramento de Proteína , Estrutura Terciária de Proteína , Saxitoxina/química , Sódio/química , Tetrodotoxina/química
19.
Biophys J ; 87(3): 1526-36, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15345533

RESUMO

Crystallographic studies of K(+) channels in the closed (KcsA) and open (MthK) states suggest that Gly(99) (KcsA numbering) in the inner helices serves as a gating hinge during channel activation. However, some P-loop channels have larger residues in the corresponding position. The comparison of x-ray structures of KcsA and MthK shows that channel activation alters backbone torsions and helical H-bonds in residues 95-105. Importantly, the changes in Gly(99) are not the largest ones. This raises questions about the mechanism of conformational changes upon channel gating. In this work, we have built a model of the open KcsA using MthK as a template and simulated opening and closing of KcsA by constraining C-ends of the inner helices at a gradually changing distance from the pore axis without restraining mobility of the helices along the axis. At each imposed distance, the energy was Monte Carlo-minimized. The channel-opening and channel-closing trajectories arrived to the structures in which the backbone geometry was close to that seen in MthK and KcsA, respectively. In the channel-opening trajectory, the constraints-induced lateral forces caused kinks at midpoints of the inner helices between Val(97) and Gly(104) but did not destroy interdomain contacts, the pore helices, and the selectivity filter. The simulated activation of the Gly(99)Ala mutant yielded essentially similar results. Analysis of interresidue energies shows that the N-terminal parts of the inner helices form strong attractive contacts with the pore helices and the outer helices. The lateral forces induce kinks at the position where the helix-breaking torque is maximal and the intersegment contacts vanish. This mechanism may be conserved in different P-loop channels.


Assuntos
Proteínas de Bactérias/química , Canais de Potássio/química , Potássio/química , Alanina/química , Proteínas de Bactérias/metabolismo , Fenômenos Biofísicos , Biofísica , Simulação por Computador , Cristalografia por Raios X , Glicina/química , Modelos Moleculares , Método de Monte Carlo , Mutação , Canais de Potássio/metabolismo , Conformação Proteica , Estrutura Terciária de Proteína , Sensibilidade e Especificidade
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