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1.
Ecohealth ; 15(4): 768-776, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30315510

RESUMO

Conditional cash transfers (CCTs)-cash payments provided to households or specific household members who meet defined conditions or fulfill certain behaviors-have been extensively used in India to encourage antenatal care, institutional delivery, and vaccination. This paper describes the social design and technical development of a low-cost, meal-counting stove use monitor (the Pink Key) that enables a CCT based on liquefied petroleum gas (LPG) usage and presents pilot data from its testing and the initial deployment. The system consists of a sensing harness attached to a two-burner LPG stove and an easily removable datalogger. For each cooking event with LPG, households receive 2 rupees-less than the cost of fuel, but enough to partially defray LPG refill costs. The system could enable innovative "self-monitoring" at a large scale-participants initiate the CCT by bringing their Pink Key to antenatal clinic visits, where care providers download data and initiate payments, and participants return the sensor to their stove at home. The system aligns with existing Indian programs to improve health among poor, pregnant women, and contributes a new method to encourage the use of clean cooking technologies.


Assuntos
Técnicas de Observação do Comportamento/instrumentação , Culinária/economia , Culinária/instrumentação , Financiamento Governamental , Poluição do Ar em Ambientes Fechados/prevenção & controle , Desenho de Equipamento/instrumentação , Características da Família , Feminino , Humanos , Índia , Motivação , Gravidez , População Rural
2.
Sensors (Basel) ; 17(8)2017 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-28812989

RESUMO

Over the last 20 years, the Kirk R. Smith research group at the University of California Berkeley-in collaboration with Electronically Monitored Ecosystems, Berkeley Air Monitoring Group, and other academic institutions-has developed a suite of relatively inexpensive, rugged, battery-operated, microchip-based devices to quantify parameters related to household air pollution. These devices include two generations of particle monitors; data-logging temperature sensors to assess time of use of household energy devices; a time-activity monitoring system using ultrasound; and a CO2-based tracer-decay system to assess ventilation rates. Development of each system involved numerous iterations of custom hardware, software, and data processing and visualization routines along with both lab and field validation. The devices have been used in hundreds of studies globally and have greatly enhanced our understanding of heterogeneous household air pollution (HAP) concentrations and exposures and factors influencing them.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar , Monitoramento Ambiental , Utensílios Domésticos , Material Particulado
3.
PLoS One ; 8(8): e73251, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24009742

RESUMO

Interventions are needed to protect the health of children who live with smokers. We pilot-tested a real-time intervention for promoting behavior change in homes that reduces second hand tobacco smoke (SHS) levels. The intervention uses a monitor and feedback system to provide immediate auditory and visual signals triggered at defined thresholds of fine particle concentration. Dynamic graphs of real-time particle levels are also shown on a computer screen. We experimentally evaluated the system, field-tested it in homes with smokers, and conducted focus groups to obtain general opinions. Laboratory tests of the monitor demonstrated SHS sensitivity, stability, precision equivalent to at least 1 µg/m(3), and low noise. A linear relationship (R(2) = 0.98) was observed between the monitor and average SHS mass concentrations up to 150 µg/m(3). Focus groups and interviews with intervention participants showed in-home use to be acceptable and feasible. The intervention was evaluated in 3 homes with combined baseline and intervention periods lasting 9 to 15 full days. Two families modified their behavior by opening windows or doors, smoking outdoors, or smoking less. We observed evidence of lower SHS levels in these homes. The remaining household voiced reluctance to changing their smoking activity and did not exhibit lower SHS levels in main smoking areas or clear behavior change; however, family members expressed receptivity to smoking outdoors. This study established the feasibility of the real-time intervention, laying the groundwork for controlled trials with larger sample sizes. Visual and auditory cues may prompt family members to take immediate action to reduce SHS levels. Dynamic graphs of SHS levels may help families make decisions about specific mitigation approaches.


Assuntos
Poluição do Ar em Ambientes Fechados/prevenção & controle , Monitoramento Ambiental/instrumentação , Monitoramento Ambiental/métodos , Família , Material Particulado , Poluição por Fumaça de Tabaco/prevenção & controle , Adolescente , Adulto , Atitude Frente a Saúde , Feminino , Comportamentos Relacionados com a Saúde , Humanos , Pessoa de Meia-Idade , Material Particulado/análise , Adulto Jovem
4.
Environ Sci Process Impacts ; 15(2): 433-9, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25208708

RESUMO

Exposure to particles with aerodynamic diameters less than 2.5 µm is estimated to cause significant morbidity and mortality worldwide leading many countries to develop ambient air pollution standards and guidelines. At local scales, community and environmental justice groups are also concerned about PM 2.5 concentrations that may be elevated above regional concentrations typically measured by centrally located monitors and standards as well. In an attempt to develop a low cost, easy to use monitor we evaluated a low-cost optical particle counter, the Dylos™, as a fine particulate mass sensor. Modified into a system called the Berkeley Aerosol Information Recording System (BAIRS), we compared performance against standard commercial instruments in chambers using polystyrene latex spheres, ammonium sulphate, and woodsmoke and in an urban ambient setting. Overall we find that the limit of detection of the BAIRS is less than 1 µg m (-3) and the resolution is better than 1 µg m(-3) for PM 2.5. The BAIRS sizes small (<0.5 µm) particles, and is able to accurately estimate the mass concentration of particles of varying composition including organic, inorganic, and ambient particles. It is able to measure concentrations up to 10.0 mg m (-3). In an ambient roof-top test of the BAIRS and a more expensive commercially available light scattering particle monitor the BAIRS response tracked well with the commercial monitor and daily means were within 80% of each other. We conclude that with appropriate modification the system could be developed into an accurate low cost realtime particle mass monitor for use in a wide range of applications.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/instrumentação , Material Particulado/análise , Monitoramento Ambiental/economia , Modelos Estatísticos , Peso Molecular , Tamanho da Partícula
5.
Nat Commun ; 3: 716, 2012 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-22395607

RESUMO

Viremic controllers and elite controllers/suppressors maintain control over HIV-1 replication. Some studies have suggested that control is a result of infection with a defective viral strain, while others suggested host immune factors have a key role. Here we document two HIV-1 transmission pairs: one consisting of a patient with progressive disease and an individual who became an elite suppressor, and the second consisting of a patient with progressive disease and a viremic controller. In contrast to another elite suppressor transmission pair, virus isolated from all patients was fully competent. These data suggest that some viremic controllers and elite suppressors are infected with HIV-1 isolates that replicate vigorously in vitro and are able to cause progressive disease in vivo. These data suggest that host factors have a dominant role in the control of HIV-1 infection, thus it may be possible to control fully pathogenic HIV-1 isolates with therapeutic vaccination.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Infecções por HIV/imunologia , Infecções por HIV/virologia , Sobreviventes de Longo Prazo ao HIV , HIV-1/fisiologia , Replicação Viral , Adulto , Sequência de Aminoácidos , Terapia Antirretroviral de Alta Atividade , Sequência de Bases , Contagem de Linfócito CD4 , Linfócitos T CD4-Positivos/virologia , Linfócitos T CD8-Positivos/imunologia , Progressão da Doença , Suscetibilidade a Doenças , Feminino , Infecções por HIV/tratamento farmacológico , Infecções por HIV/transmissão , HIV-1/imunologia , HIV-1/isolamento & purificação , Interações Hospedeiro-Patógeno , Humanos , Masculino , Dados de Sequência Molecular , Carga Viral , Viremia , Adulto Jovem , Produtos do Gene gag do Vírus da Imunodeficiência Humana/química , Produtos do Gene gag do Vírus da Imunodeficiência Humana/imunologia
6.
Spine J ; 9(5): 387-95, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-18809358

RESUMO

BACKGROUND CONTEXT: Lumbar zygapophyseal joint (Z-joint) synovial cysts can cause low back pain (LBP), spinal stenosis, and lower extremity radiculopathy. In the literature, there are several minimally invasive techniques described with mixed results. Typical recommended treatment is surgical resection of the cyst. Currently, there is little information available concerning the efficacy and outcome with treatment of Z-joint synovial cyst by percutaneous, fluoroscopic, contrast-enhanced distention, and rupture. PURPOSE: To evaluate the therapeutic value and safety of Z-joint cyst rupture in symptomatic patients. STUDY DESIGN/SETTING: Retrospective cohort study in an academic outpatient physiatric spine practice. PATIENT SAMPLE: Thirty-two patients with moderate-to-severe LBP and leg pain (18 women and 14 men with an age range of 46-86 y; mean age, 66 y) with an average preprocedure symptom duration of 5 months. The patient's clinical symptoms correlated with magnetic resonance imaging studies documenting the presence of a synovial cyst at the corresponding level and side of symptoms. Patients had at least 6 months follow-up (range, 6-24). OUTCOME MEASURES: Numerical Pain Rating Scale, Roland-Morris Disability Questionnaire, North American Spine Society four-point patient satisfaction survey, recurrence of synovial cyst requiring repeat rupture, and need for surgical intervention. METHODS: Patients with symptomatic lumbar Z-joint synovial cyst were identified and their charts were reviewed. Patients included in the study either had symptomatic lumbar LBP or LBP with associated lower extremity radiculopathy. All patients in the study had magnetic resonance imaging's documenting Z-joint synovial cyst that corresponded with the patients' clinical symptoms. All patients received fluoroscopically guided, contrast-enhanced, percutaneous facet cyst distention and rupture followed by an intra-articular facet joint injection of 1 cc kenalog and 1 cc of 1% lidocaine. Seventeen of the patients also received a transforaminal epidural steroid injection just before facet cyst rupture. Telephone follow-up was conducted on all patients. RESULTS: Excellent long-term (average follow-up 1 y; range, 6-24 mo) pain relief was achieved in 23 (72%) of 32 patients undergoing facet cyst rupture. Twelve patients (37.5%) had synovial cyst recurrence and 11 chose to undergo repeat rupture, which resulted in 5 patients (45%) obtaining complete relief of symptoms and 6 patients (55%) requiring surgical intervention for cyst removal. Fisher exact test demonstrated that all patients who did not have a cyst recurrence were a success and obtained complete relief of symptoms (p<.0002). Patients who underwent a repeat rupture had a 50% chance of a successful outcome. There was no statistical significance between a successful outcome and level of facet cyst rupture, the presence of spondylolisthesis, sex, age, or having a transforaminal epidural steroid injection at the time of the procedure. Wilcoxon signed-rank test demonstrated that the difference in Numerical Pain Rating Scale and Roland-Morris Disability Questionnaire scores before and after the procedure was statistically significant (p<.0001). No complications were reported. CONCLUSIONS: Fluoroscopic percutaneous Z-joint cyst rupture appears to be a safe and effective minimally invasive treatment option. This procedure should be considered before surgical intervention.


Assuntos
Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Procedimentos Ortopédicos/métodos , Cisto Sinovial/cirurgia , Articulação Zigapofisária/cirurgia , Corticosteroides/administração & dosagem , Idoso , Idoso de 80 Anos ou mais , Feminino , Fluoroscopia , Humanos , Injeções Epidurais , Dor Lombar/etiologia , Dor Lombar/cirurgia , Vértebras Lombares , Masculino , Pessoa de Meia-Idade , Dor/tratamento farmacológico , Dor/cirurgia , Estudos Retrospectivos , Articulação Zigapofisária/patologia
7.
Med Ref Serv Q ; 26(4): 45-63, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-18086641

RESUMO

Academic health sciences libraries can take various approaches to support the problem-based learning component of the curriculum. This article presents one such approach taken to integrate information navigation skills into the small group discussion part of the Pathophysiology course in the second year of the Dental school curriculum. Along with presenting general resources for the course, the Library Toolkit introduced an algorithmic approach to finding answers to sample clinical case questions. While elements of Evidence-Based Practice were introduced, the emphasis was on teaching students to navigate relevant resources and apply various database search techniques to find answers to the clinical problems presented.


Assuntos
Algoritmos , Bibliotecas Odontológicas , Aprendizagem Baseada em Problemas/organização & administração , Cidade de Nova Iorque , Estudos de Casos Organizacionais , Faculdades de Odontologia , Estados Unidos
8.
J Environ Monit ; 9(10): 1099-106, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17909644

RESUMO

We have developed a small, light, passive, inexpensive, datalogging particle monitor called the "UCB" (University of California Berkeley particle monitor). Following previously published laboratory assessments, we present here results of tests of its performance in field settings at high particle concentrations. We demonstrate the mass sensitivity of the UCB in relation to gravimetric filter-based PM(2.5) mass estimates as well as commercial light-scattering instruments co-located in field chamber tests and in kitchens of wood-burning households. The coefficient of variation of the unadjusted UCB mass response in relation to gravimetric estimates was 15%. Although requiring adjustment for differences in sensitivity, inter-monitor performance was consistently high (r(2) > 0.99). Moreover, the UCB can consistently estimate PM(2.5) mass concentrations in wood-burning kitchens (Pearson r(2) = 0.89; N = 99), with good agreement between duplicate measures (Pearson r(2) = 0.94; N = 88). In addition, with appropriate cleaning of the sensing chamber, UCB mass sensitivity does not decrease with time when used intensively in open woodfire kitchens, demonstrating the significant potential of this monitor.


Assuntos
Monitoramento Ambiental/economia , Monitoramento Ambiental/instrumentação , Luz , Material Particulado/análise , Espalhamento de Radiação , Guatemala , México , Politetrafluoretileno , Reprodutibilidade dos Testes , Madeira
9.
Med Ref Serv Q ; 26(3): 55-74, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17915631

RESUMO

Searching for alternatives to using animals in research is not a standard service currently offered by most medical research libraries. The goal of this article is to demystify this type of expert search for medical librarians and to do so using a language they know well, that of the Medical Subject Headings (MeSH) thesaurus. An attempt is made in this paper to discuss possible search strategies and to include examples of recommended approaches to searching-all in the context of the 3Rs of alternatives: Replacement, Refinement, and Reduction.


Assuntos
Experimentação Animal , Armazenamento e Recuperação da Informação/métodos , Medical Subject Headings , Animais , Bases de Dados Bibliográficas , Estados Unidos
10.
J Orthop Res ; 24(11): 2106-13, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16947777

RESUMO

Medial collateral ligament (MCL) injuries heal by a wound repair scar response controlled by a complex cellular and cytokine environment. Many enzymes participate in wound repair, particularly the matrix metalloproteinases. We hypothesize macrophage metalloelastase (MME/MMP-12) deficiency results in impaired healing of MCL injury. One hundred fifty MME-deficient and 150 WT (MME+/+) mice underwent knee MCL transection with the opposite knee as a sham operated control. Mice were sacrificed at 3, 7, 28, 42, and 56 days. At each of the five time points, 15 mice were utilized for biological and 15 were utilized for biomechanical testing. Outcome measures were the presence of macrophages to represent the inflammatory phase of wound healing, collagen synthesis to assay for matrix repair, and biomechanical testing for repair strength. Immunohistochemistry demonstrated significantly fewer macrophages in cut MCLs from MME-deficient mice versus wild-type (WT) mice at 3, 7, 28, and 42 days (all p

Assuntos
Macrófagos/patologia , Metaloproteinase 12 da Matriz/deficiência , Ligamento Colateral Médio do Joelho/lesões , Cicatrização , Animais , Colágeno Tipo I/metabolismo , Modelos Animais de Doenças , Análise de Falha de Equipamento , Técnica Indireta de Fluorescência para Anticorpo , Macrófagos/metabolismo , Metaloproteinase 12 da Matriz/genética , Metaloproteinase 12 da Matriz/metabolismo , Ligamento Colateral Médio do Joelho/patologia , Ligamento Colateral Médio do Joelho/fisiopatologia , Camundongos , Camundongos Knockout , Joelho de Quadrúpedes/cirurgia , Estresse Mecânico
11.
Am J Sports Med ; 34(10): 1599-603, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16861581

RESUMO

BACKGROUND: Elbow medial ulnar collateral ligament tears often result in pain and instability that may be career threatening in overhead-throwing athletes. Surgical reconstruction is frequently chosen to treat this injury. Ulnar collateral ligament reconstruction as described by Jobe is the most commonly used technique. Testing of this construct has not demonstrated that the biomechanical parameters of the native ligament are restored. A more recent construct, the docking technique, may more reliably reproduce these factors. HYPOTHESIS: Increasing the number of strands of palmaris longus tendon graft used in ulnar collateral ligament reconstruction and tensioning them using the docking technique result in a construct with improved biomechanical parameters as compared with the Jobe technique. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty-three fresh-frozen human cadaveric elbows were randomized into 3 subgroups: Jobe (11), docking (12), and native (10). The Jobe and docking groups underwent reconstruction using their described palmaris tendon graft constructs. The ulnar collateral ligament was left intact in the native group. Elbows were potted and tested using a servohydraulic materials testing machine to apply a valgus moment at 30 degrees of elbow flexion. Maximal moments to failure, stiffness, and strain at maximal moment and with a 3 N.m force applied were determined using a 2-camera motion analysis system to track reflective markers spanning the site. RESULTS: The docking (14.3 N.m) and native (18.8 N.m) subgroups resulted in higher maximal moment to failure than did the Jobe (8.9 N.m) subgroup (P < .001). There was no significant difference between native and docking groups (P > .05). Native ligaments were stiffer (301.4 N.m) than were Jobe (74.3 N.m) or docking (80.8 N.m; P < .001). Native ligaments demonstrated lower strain at maximal force (0.087 mm/mm) and 3 N.m forces (0.030 mm/mm) than did the Jobe (0.198/0.057 mm/mm) or docking (0.287/0.042 mm/mm) subgroups. There was no difference in stiffness or strain between the Jobe and docking subgroups (P > .05). CONCLUSION: Neither technique reproduced the biomechanical profile of the native ulnar collateral ligament; the findings of this study suggest that the docking construct may offer initial biomechanical advantage over the Jobe construct.


Assuntos
Artroplastia/métodos , Beisebol/lesões , Ligamentos Colaterais/lesões , Lesões no Cotovelo , Instabilidade Articular/cirurgia , Tendões/transplante , Análise de Variância , Fenômenos Biomecânicos , Cadáver , Ligamentos Colaterais/cirurgia , Articulação do Cotovelo/cirurgia , Humanos , Pessoa de Meia-Idade , Ruptura , Estatísticas não Paramétricas , Técnicas de Sutura , Ulna
12.
J Air Waste Manag Assoc ; 56(6): 789-99, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16805403

RESUMO

In developing countries, high levels of particle pollution from the use of coal and biomass fuels for household cooking and heating are a major cause of ill health and premature mortality. The cost and complexity of existing monitoring equipment, combined with the need to sample many locations, make routine quantification of household particle pollution levels difficult. Recent advances in technology, however, have enabled the development of a small, portable, data-logging particle monitor modified from commercial smoke alarm technology that can meet the needs of surveys in the developing world at reasonable cost. Laboratory comparisons of a prototype particle monitor developed at the University of California at Berkeley (UCB) with gravimetric filters, a tapered element oscillating microbalance, and a TSI DustTrak to quantify the UCB particle monitor response as a function of both concentration and particle size and to examine sensor response in relation to changes in temperature, relative humidity, and elevation are presented here. UCB particle monitors showed good linearity in response to different concentrations of laboratory-generated oleic acid aerosols with a coarse (mass median diameter, 2.1 microm) and fine (mass median diameter, 0.27-0.42 microm) size distributions (average r2 = 0.997 +/- 0.005). The photoelectric and ionization chamber showed a wide range of responses based on particle size and, thus, require calibration with the aerosol of interest. The ionization chamber was five times more sensitive to fine rather than coarse particles, whereas the photoelectric chamber was five times more sensitive to coarse than fine. The ratio of the response between the two sensors has the potential for mass calibration of individual data points based on estimated parameters of the size distribution. The results demonstrate the significant potential of this monitor, which will facilitate the evaluation of interventions (improved fuels, stoves, and ventilation) on indoor air pollution levels and research on the impacts of indoor particle levels on health in developing countries.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Poeira/análise , Monitoramento Ambiental/instrumentação , Aerossóis/análise , Umidade , Modelos Teóricos , Ácido Oleico/análise , Temperatura
13.
Evid Based Cardiovasc Med ; 8(1): 2-7, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16379880
14.
Am J Sports Med ; 31(5): 660-6, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12975183

RESUMO

BACKGROUND: Medial collateral ligament injuries heal by a scar response. HYPOTHESIS: Increased hemorrhage at the site of medial collateral ligament injury improves healing. STUDY DESIGN: Controlled laboratory study. METHODS: Ninety-six mice were divided into two groups. Group 1 mice underwent knee medial collateral ligament transection with the opposite knee as a sham-operated control and group 2 animals additionally had 0.25 ml of tail cut blood pipetted to the medial collateral ligament transection site and sham-operated opposite knee. Ligament specimens were harvested at 3, 7, 21, and 28 days. RESULTS: Immunohistochemical analysis demonstrated peak macrophage counts at day 7 in all transected specimens. Macrophage counts were higher in group 2 than in group 1 at all time points, with a statistically significant increase of macrophages noted at day 7. In situ hybridization demonstrated increased collagen gene expression, with peaks at 7 and 28 days after transection. Group 2 animals showed increased gene expression at all time points as compared with group 1, with a statistically significant increase noted at 7 and 28 days. Biomechanical testing demonstrated progressive healing at each time point. At 28 days, the load to failure was 67% that of the sham-operated knee. CONCLUSIONS: This study suggests there is an increased healing response with bleeding at the ligament injury site. CLINICAL RELEVANCE: Identification of the factors involved with increased healing may allow manipulation of the healing response in the clinical setting.


Assuntos
Hemorragia , Ligamento Colateral Médio do Joelho/cirurgia , Animais , Fenômenos Biomecânicos , Colágeno/biossíntese , Modelos Animais de Doenças , Regulação da Expressão Gênica , Imuno-Histoquímica , Macrófagos , Ligamento Colateral Médio do Joelho/patologia , Camundongos , Cicatrização
15.
Ann Emerg Med ; 42(1): 136-49, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12827133

RESUMO

Practitioners seeking enhancement of clinical care through consideration of research require rapid and efficient point-of-care access to current studies and summaries pertaining to specific clinical queries. MEDLINE and other large databases usually contain the citations relevant to such questions but frequently fall short of the practical requirements of busy clinicians. We present a summary of the knowledge and skills required for physicians to select and use smaller databases appropriate to particular types of questions arising from emergency care. We outline a step-by-step approach that begins at the bedside with the sorting of questions into appropriate categories of knowledge and research design. We identify commonly encountered pitfalls in the process of connecting a particular question to an appropriate database. We illustrate the approach through a set of demonstration questions pertaining to patients presenting to emergency departments with chest pain consistent with acute coronary ischemia. We describe a selection of resources and databases and summarize their performance in locating articles relevant to the demonstration questions.


Assuntos
Bases de Dados Factuais , Medicina de Emergência , Algoritmos , Dor no Peito/diagnóstico , Diagnóstico Diferencial , Medicina Baseada em Evidências , Humanos , Infarto do Miocárdio/diagnóstico , Publicações Periódicas como Assunto
16.
J Physiol ; 545(3): 975-86, 2002 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-12482900

RESUMO

The release of endothelium-derived relaxing factors, such as nitric oxide (NO), is dependent on an increase in intracellular calcium levels ([Ca(2+)](i)) within endothelial cells. Endothelial cell membrane potential plays a critical role in the regulation of [Ca(2+)](i) in that calcium influx from the extracellular space is dependent on membrane hyperpolarization. In this study, the effect of inhibition of vascular smooth muscle delayed rectifier K(+) (K(DR)) channels by 4-aminopyridine (4-AP) on endothelium-dependent relaxation of rat basilar artery to acetylcholine (ACh) was assessed. ACh-evoked endothelium-dependent relaxations were inhibited by N-(Omega)-nitro-L-arginine (L-NNA) or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), confirming a role for NO and guanylyl cyclase. 4-AP (300 microM) also suppressed ACh-induced relaxation, with the maximal response reduced from approximately 92 to approximately 33 % (n = 11; P < 0.01). However, relaxations in response to exogenous NO, applied in the form of authentic NO, sodium nitroprusside or diethylamineNONOate (DEANONOate), were not affected by 4-AP treatment (n = 3-11). These data are not consistent with the view that 4-AP-sensitive K(DR) channels are mediators of vascular hyperpolarization and relaxation in response to endothelium-derived NO. Inhibition of ACh-evoked relaxation by 4-AP was reversed by pinacidil (0.5-1 microM; n = 5) or 18beta-glycyrrhetinic acid (18betaGA; 5 microM; n = 5), indicating that depolarization and electrical coupling of the smooth muscle to the endothelium were involved. 4-AP caused depolarization of both endothelial and vascular smooth muscle cells of isolated segments of basilar artery (mean change 11 +/- 1 and 9 +/- 2 mV, respectively; n = 15). Significantly, 18betaGA almost completely prevented the depolarization of endothelial cells (n = 6), but not smooth muscle cells (n = 6) by 4-AP. ACh-induced hyperpolarization of endothelium and smooth muscle cells was also reduced by 4-AP, but this inhibition was not observed in the combined presence of 4-AP and 18betaGA. These data indicate that 4-AP can induce an indirect inhibition of endothelium-dependent relaxation in the rat basilar artery by electrical coupling of smooth muscle membrane depolarization to the endothelium via myo-endothelial gap junctions.


Assuntos
Artéria Basilar/fisiologia , Endotélio Vascular/fisiologia , Junções Comunicantes/fisiologia , Músculo Liso Vascular/fisiologia , Vasodilatação/fisiologia , 4-Aminopiridina/antagonistas & inibidores , 4-Aminopiridina/farmacologia , Acetilcolina/farmacologia , Animais , Ácido Glicirretínico/análogos & derivados , Ácido Glicirretínico/farmacologia , Técnicas In Vitro , Masculino , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Óxido Nítrico/farmacologia , Pinacidil/farmacologia , Bloqueadores dos Canais de Potássio/farmacologia , Ratos , Ratos Sprague-Dawley , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologia
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