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1.
J Environ Manage ; 351: 119731, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38169249

RESUMO

Wildland fire incident commanders make wildfire response decisions within an increasingly complex socio-environmental context. Threats to human safety and property, along with public pressures and agency cultures, often lead commanders to emphasize full suppression. However, commanders may use less-than-full suppression to enhance responder safety, reduce firefighting costs, and encourage beneficial effects of fire. This study asks: what management, socioeconomic, environmental, and fire behavior characteristics are associated with full suppression and the less-than-full suppression methods of point-zone protection, confinement/containment, and maintain/monitor? We analyzed incident report data from 374 wildfires in the United States northern Rocky Mountains between 2008 and 2013. Regression models showed that full suppression was most strongly associated with higher housing density and earlier dates in the calendar year, along with non-federal land jurisdiction, regional and national incident management teams, human-caused ignitions, low fire-growth potential, and greater fire size. Interviews with commanders provided decision-making context for these regression results. Future efforts to encourage less-than-full suppression should address the complex management context, in addition to the biophysical context, of fire response.


Assuntos
Incêndios , Incêndios Florestais , Estados Unidos , Humanos , Previsões , Gestão de Riscos
2.
JAMA Netw Open ; 6(12): e2345906, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-38039002

RESUMO

Importance: Novel hormonal therapy (NHT) agents have been shown to prolong overall survival in numerous randomized clinical trials for patients with advanced prostate cancer (PCa). There is a paucity of data regarding the pattern of use of these agents in patients from different racial and ethnic groups. Objective: To assess racial and ethnic disparities in the use of NHT in patients with advanced PCa. Design, Setting, and Participants: This cohort study comprised all men diagnosed with de novo advanced PCa (distant metastatic [M1], regional [N1M0], and high-risk localized [N0M0] per Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy [STAMPEDE] trial criteria) with Medicare Part A, B, and D coverage between January 1, 2011, and December 31, 2017, in a Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database including prescription drug records. Data analysis took place from January through May 2023. Exposures: Race and ethnicity (Black [non-Hispanic], Hispanic, White, or other [Alaska Native, American Indian, Asian, Pacific Islander, or not otherwise specified and unknown]) abstracted from the SEER data fields. Main Outcomes and Measures: The primary outcome was receipt of an NHT agent (abiraterone, enzalutamide, apalutamide, or darolutamide) using a time-to-event approach. Results: The study included 3748 men (median age, 75 years [IQR, 70-81 years]). A total of 312 (8%) were Black; 263 (7%), Hispanic; 2923 (78%), White; and 250 (7%) other race and ethnicity. The majority of patients had M1 disease (2135 [57%]) followed by high-risk N0M0 (1095 [29%]) and N1M0 (518 [14%]) disease. Overall, 1358 patients (36%) received at least 1 administration of NHT. White patients had the highest 2-year NHT utilization rate (27%; 95% CI, 25%-28%) followed by Hispanic patients (25%; 95% CI, 20%-31%) and patients with other race or ethnicity (23%; 95% CI, 18%-29%), with Black patients having the lowest rate (20%; 95% CI, 16%-25%). Black patients had significantly lower use of NHT compared with White patients, which persisted at 5 years (37% [95% CI, 31%-43%] vs 44% [95% CI, 42%-46%]; P = .02) and beyond. However, there was no significant difference between White patients and Hispanic patients or patients with other race or ethnicity in NHT utilization (eg, 5 years: Hispanic patients, 38% [95% CI, 32%-46%]; patients with other race and ethnicity: 41% [95% CI, 35%-49%]). Trends of lower utilization among Black patients persisted in the patients with M1 disease (eg, vs White patients at 5 years: 51% [95% CI, 44%-59%] vs 55% [95% CI, 53%-58%]). After adjusting for patient, disease, and sociodemographic factors in multivariable analysis, Black patients continued to have a significantly lower likelihood of NHT initiation (adjusted subdistribution hazard ratio, 0.76; 95% CI, 0.61-0.94, P = .01). Conclusions and Relevance: In this cohort study of Medicare beneficiaries with advanced PCa, receipt of NHT agents was not uniform by race, with decreased use observed in Black patients compared with the other racial and ethnic groups, likely due to multifactorial obstacles. Future studies are needed to identify strategies to address the disparities in the use of these survival-prolonging therapies in Black patients.


Assuntos
Disparidades em Assistência à Saúde , Hormônios , Neoplasias da Próstata , Idoso , Humanos , Masculino , Estudos de Coortes , Etnicidade , Medicare , Neoplasias da Próstata/terapia , Estados Unidos , Grupos Raciais , Hormônios/uso terapêutico
3.
Sci Bull (Beijing) ; 68(19): 2236-2246, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37604723

RESUMO

Sustainable development in impoverished areas is still a global challenge owing to trade-offs between development and conservation. There are large poverty-stricken areas (PSAs) in China, which overlap highly with ecologically sensitive areas. China has made great efforts to alleviate poverty over the years. The coordinated relationship between the social economy and the environment in PSAs, however, remains under-recognized. This study developed a county-level index system encompassing the socioeconomic and environmental sectors of China's PSAs. The integrated indexes of the two sectors were developed to reveal the spatial-temporal socioeconomic and environmental patterns and coupling coordination degree (CCD) levels were calculated to assess the coordinated relationships between them. The CCD indicated the increasingly coordinated development of socioeconomic and environmental conditions in China's PSAs from 2000 to 2020. Meanwhile, although the socioeconomic index achieved considerable growth with a growth rate of 58.4%, the environmental index was mildly improved with a growth rate of 19.6%, instead of a reduction. PSAs still have a large gap in socioeconomic development compared to non-poor areas; however, PSAs perform better in environmental index. Overall, the increased coordinated development between the social economy and the environment from 2000 to 2020 can be attributed to China's long-term, large-scale, and targeted interventions in poverty reduction and environmental conservation. Further, benefiting from the geodiversity of China, we identified four poverty reduction models which include advantageously, sustained, periodic, and limited effective models, on the basis of CCD change patterns. The four models can provide valuable experience for the rest of the world in tackling similar trade-offs of poverty reduction and environmental challenges.

4.
Ultrasound Med Biol ; 49(7): 1595-1601, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37088605

RESUMO

OBJECTIVE: The aim of this study was to explore the value of contrast-enhanced ultrasound (CEUS) combined with 2-D strain imaging in evaluating carotid plaque vulnerability and the correlations among CEUS perfusion parameters, strain parameters and histopathological findings in different plaque segments. METHODS: Patients with carotid artery stenosis who underwent carotid endarterectomy (CEA) at the First Affiliated Hospital of Xinjiang Medical University from September 2020 to June 2021 underwent preoperative carotid artery 2-D ultrasonography and CEUS. The plaques were divided into three segments: the proximal end of the shoulder, central cap and distal end of the shoulder. The peak intensity (PI) value and strain rate parameters of the regions of interest were analyzed. Plaques were divided into a stable group (8 cases) and an unstable group (19 cases). The microvascular density (MVD) and vascular endothelial growth factor (VEGF) expression of each patch in the unstable group were analyzed. RESULTS: The peak strain during the systolic period in each plaque segment in both groups showed the following pattern: proximal end shoulder > distal end shoulder > top (p < 0.05). The PI value for CEUS is also represented. In the unstable group, the PI values of each segment of the plaque were positively correlated with the MVD, near-center PI value and VEGF average optical density value. The average optical density of each segment was positively correlated with the MVD (p < 0.05). There were positive correlations between the PI values of the proximal and distal shoulder and the strain values (p < 0.05), and the MVD value of each segment, VEGF value and strain value were positively correlated (p < 0.05). CONCLUSION: PI and the pathological tissue components represented by CEUS were positively correlated with the mechanical parameters of the plaque along the long axis. There may be overlap between the high shear stress area of the plaque and the neovascular aggregation area, and the combination of the two has certain significance for assessing the vulnerability of the plaque.


Assuntos
Estenose das Carótidas , Endarterectomia das Carótidas , Placa Aterosclerótica , Humanos , Fator A de Crescimento do Endotélio Vascular , Meios de Contraste , Artérias Carótidas/diagnóstico por imagem , Artérias Carótidas/patologia , Ultrassonografia , Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/patologia , Placa Aterosclerótica/diagnóstico por imagem , Placa Aterosclerótica/patologia , Neovascularização Patológica
5.
Prostate Cancer Prostatic Dis ; 26(3): 625-627, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-36966268

RESUMO

It is unclear whether cancer patients enrolled in clinical trials have improved outcomes compared with non-study patients. We compared prostate cancer-specific mortality (PCSM) in patients in a real-world setting (SEER-Medicare database) versus on a trial (NRG/RTOG 0521). The 7-year freedom from PCSM was superior in trial patients (92.4% vs. 88.1%, sHR = 1.77 [95% CI 1.05-2.97], P = 0.03). Black trial patients had significantly superior freedom from PCSM than Black real-world patients (sHR 6.52, 95% CI 1.43-29.72, P = 0.02), which was not seen among non-Black patients. Trial patients may have improved outcomes, and racial disparities are accentuated in the real world.


Assuntos
Neoplasias da Próstata , Idoso , Masculino , Humanos , Estados Unidos/epidemiologia , Neoplasias da Próstata/terapia , Medicare , Antígeno Prostático Específico , Próstata , Programa de SEER
6.
Artigo em Inglês | MEDLINE | ID: mdl-36613127

RESUMO

Conservationists recognize that protected areas (PAs) have limited prospects without the involvement and support of local people. As a governance strategy, community participation is to implement the coordinated development of communities and PAs. However, the effects of community participation on national park governance have rarely been tested. Therefore, the present study used a mixed-method approach that is derived from the International Union for Conservation of Nature (IUCN) green list of protected and conserved areas (PCA) conservation outcomes framework, calibrated to the indigenous peoples and local communities' (IPLCs) self-assessments about the outcomes of community participation on national park governance to explore the community participation effects. Our results show that management efficiency controls governance outcomes. Potatso National Park's transformation from the tourism development model to national park is still ongoing, and there exists quite a few problems. We conclude that a successful national park governance as envisaged by the "ecological civilization" paradigm requires a balance of government regulation, participation of various stakeholders in decision-making and discussion, compensation, as well as sustainable access to environmental resources by the affected populations.


Assuntos
Conservação dos Recursos Naturais , Parques Recreativos , Humanos , Conservação dos Recursos Naturais/métodos , Participação da Comunidade , Civilização , China
7.
Artigo em Inglês | MEDLINE | ID: mdl-34770001

RESUMO

Assessing the health of the ecosystem based on the landscape pattern of national parks can facilitate policy makers in formulating more targeted conservation policies to better manage national park ecosystems. To analyze the landscape patterns and characteristics of the national park, the ecosystem health evaluation index system of the national park was constructed using the vigor-organization-resilience (VOR) model to evaluate the health status. In this study, the Shennongjia National Park in China was selected as a case study area to be assessed using the index system. The results revealed that the patches of construction land and farmland are the largest in number and the most complex in shape, reflecting the obvious fragmentation of construction land and farmland patches. All patch types in this national park were evenly distributed. The results of the analysis showed that the comprehensive index of national park heath, according to the VOR model, is 0.74, indicating that the ecosystems in this study area were in a good state of health. Ecosystems in strictly protected areas of this park had the highest ecosystem health index levels, while the traditional utilization areas had the lowest. Ecosystem health levels were characterized by significant spatial agglomeration characteristics, with high-high aggregation distribution areas, mainly clustered in strictly protected areas, and low-low aggregation distribution, mainly clustered in traditional utilization areas and marginal areas. This study provided a set of ecosystem health assessment systems and their practical use in China's newly established national parks.


Assuntos
Ecossistema , Parques Recreativos , China , Conservação dos Recursos Naturais , Fazendas
8.
Appl Radiat Oncol ; 10(3): 33-40, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34671700

RESUMO

BACKGROUND AND PURPOSE: Stereotactic body radiation therapy (SBRT) has become a standard-of-care option for localized prostate cancer. While prostate SBRT has traditionally been delivered using computed-tomography-guided radiation therapy (CTgRT), MR-imaging-guided radiation therapy (MRgRT) is now available. MRgRT offers real-time soft-tissue visualization and ease of adaptive planning, obviating the need for fiducial markers, and potentially allowing for smaller planning target volume (PTV) margins. Although prior studies have focused on evaluating the cost-effectiveness of MRgRT vs CTgRT from a payor perspective, the difference in provider costs to deliver such treatments remains unknown. This study thus used time-driven activity-based costing (TDABC) to determine the difference in provider resources consumed by delivering prostate SBRT via MRgRT vs CTgRT. METHODS: Data was collected from a single academic institution where prostate SBRT is routinely performed using both CTgRT and MRgRT. Five-fraction SBRT (40 Gy total dose) was assumed to be delivered through volumetric-modulated arc therapy for CTgRT patients, and through step-and-shoot, fixed-gantry intensity-modulated radiation therapy for MRgRT patients. Process maps were constructed for each portion of the radiation delivery process via interviews/surveys with departmental personnel and by measuring CTgRT and MRgRT treatment times. Prior to simulation, only CTgRT patients underwent placement of three gold fiducial markers. Personnel capacity cost rates were calculated by dividing total personnel costs by the annual minutes worked by a given personnel. Equipment costs included both an annualized purchase price and annual maintenance costs. Ultimately, the total costs of care encompassing personnel, space/equipment, and materials were aggregated across the entire chain of care for both CTgRT and MRgRT patients in a base case. RESULTS: Direct costs associated with delivering a 5-fraction course of prostate SBRT were $1,497 higher with MRgRT than with CTgRT - comprised of personnel costs ($210 higher with MRgRT), space/equipment ($1,542 higher with MRgRT), and materials ($255 higher with CTgRT). Only CTgRT patients underwent fiducial placement, which accounted for $591. MRgRT patients were assumed to undergo both CT simulation (for electron density calculation) and MRI simulation, with the former accounting for $168. Mean time spent by patients in the treatment vault per fraction was 20 minutes (range 15-26 minutes) for CTgRT, and 31 minutes (range 30-34 minutes) for MRgRT. Patient time spent during fiducial placement (CTgRT only) was 60 minutes. Modifying the number of fractions treated would result in the cost difference of $1,497 (5 fractions) changing to $441 (1 fraction) or to $2,025 (7 fractions). CONCLUSION: This study provides an approximate comparison of the direct resources required for a radiation oncology provider to deliver prostate SBRT with CTgRT vs MRgRT. We await findings from the currently accruing phase III MIRAGE trial, which is comparing these modalities, and will subsequently measure acute and late genitourinary/gastrointestinal (GU/GI) toxicities, temporal change in quality-of-life outcomes, and 5-year biochemical, recurrence-free survival. Results from studies comparing the efficacy and safety of MRgRT vs CTgRT will ultimately allow us to put this cost difference into context.

9.
Biomed Pharmacother ; 143: 112128, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34492424

RESUMO

Gender differences have important biological significance for medical research. In this study, a bias towards males was identified in animal experiments of Damp-Heat Syndrome in traditional Chinese medicine, as was first proposed by a data mining method. Combined with the correlation between Damp-Heat Syndrome in traditional Chinese medicine and Gender differences, it was considered that Gender-related factors have a significant influence on the development of Damp-Heat Syndrome in traditional Chinese medicine. However, most traditional Chinese medicine studies ignore the key significance of Gender-related factors. This study emphasises that the development of modern traditional Chinese medicine research needs to pay full attention to the biological significance of Gender-related factors and to apply this concept to the research on the Gender equivalence strategy in basic research and the practice of personalised medical diagnosis and clinical treatment.


Assuntos
Disparidades nos Níveis de Saúde , Sistema Imunitário/fisiopatologia , Inflamação/fisiopatologia , Medicina Tradicional Chinesa , Caracteres Sexuais , Animais , Mineração de Dados , Modelos Animais de Doenças , Feminino , Humanos , Sistema Imunitário/imunologia , Sistema Imunitário/metabolismo , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/terapia , Mediadores da Inflamação/metabolismo , Masculino , Fatores de Risco , Fatores Sexuais , Síndrome , Biologia de Sistemas
10.
Lancet Infect Dis ; 20(8): 911-919, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32353347

RESUMO

BACKGROUND: Rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan, China, prompted heightened surveillance in Shenzhen, China. The resulting data provide a rare opportunity to measure key metrics of disease course, transmission, and the impact of control measures. METHODS: From Jan 14 to Feb 12, 2020, the Shenzhen Center for Disease Control and Prevention identified 391 SARS-CoV-2 cases and 1286 close contacts. We compared cases identified through symptomatic surveillance and contact tracing, and estimated the time from symptom onset to confirmation, isolation, and admission to hospital. We estimated metrics of disease transmission and analysed factors influencing transmission risk. FINDINGS: Cases were older than the general population (mean age 45 years) and balanced between males (n=187) and females (n=204). 356 (91%) of 391 cases had mild or moderate clinical severity at initial assessment. As of Feb 22, 2020, three cases had died and 225 had recovered (median time to recovery 21 days; 95% CI 20-22). Cases were isolated on average 4·6 days (95% CI 4·1-5·0) after developing symptoms; contact tracing reduced this by 1·9 days (95% CI 1·1-2·7). Household contacts and those travelling with a case were at higher risk of infection (odds ratio 6·27 [95% CI 1·49-26·33] for household contacts and 7·06 [1·43-34·91] for those travelling with a case) than other close contacts. The household secondary attack rate was 11·2% (95% CI 9·1-13·8), and children were as likely to be infected as adults (infection rate 7·4% in children <10 years vs population average of 6·6%). The observed reproductive number (R) was 0·4 (95% CI 0·3-0·5), with a mean serial interval of 6·3 days (95% CI 5·2-7·6). INTERPRETATION: Our data on cases as well as their infected and uninfected close contacts provide key insights into the epidemiology of SARS-CoV-2. This analysis shows that isolation and contact tracing reduce the time during which cases are infectious in the community, thereby reducing the R. The overall impact of isolation and contact tracing, however, is uncertain and highly dependent on the number of asymptomatic cases. Moreover, children are at a similar risk of infection to the general population, although less likely to have severe symptoms; hence they should be considered in analyses of transmission and control. FUNDING: Emergency Response Program of Harbin Institute of Technology, Emergency Response Program of Peng Cheng Laboratory, US Centers for Disease Control and Prevention.


Assuntos
Betacoronavirus/isolamento & purificação , Controle de Doenças Transmissíveis/métodos , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/transmissão , Transmissão de Doença Infecciosa/prevenção & controle , Transmissão de Doença Infecciosa/estatística & dados numéricos , Pneumonia Viral/epidemiologia , Pneumonia Viral/transmissão , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Número Básico de Reprodução , COVID-19 , Criança , Pré-Escolar , China/epidemiologia , Controle de Doenças Transmissíveis/organização & administração , Busca de Comunicante , Infecções por Coronavirus/prevenção & controle , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Estudos Retrospectivos , Medição de Risco , SARS-CoV-2 , Adulto Jovem
11.
Nat Commun ; 11(1): 650, 2020 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-32005847

RESUMO

Inadequate water quality can mean that water is unsuitable for a variety of human uses, thus exacerbating freshwater scarcity. Previous large-scale water scarcity assessments mostly focused on the availability of sufficient freshwater quantity for providing supplies, but neglected the quality constraints on water usability. Here we report a comprehensive nationwide water scarcity assessment in China, which explicitly includes quality requirements for human water uses. We highlight the necessity of incorporating water scarcity assessment at multiple temporal and geographic scales. Our results show that inadequate water quality exacerbates China's water scarcity, which is unevenly distributed across the country. North China often suffers water scarcity throughout the year, whereas South China, despite sufficient quantities, experiences seasonal water scarcity due to inadequate quality. Over half of the population are affected by water scarcity, pointing to an urgent need for improving freshwater quantity and quality management to cope with water scarcity.


Assuntos
Água Doce/análise , Abastecimento de Água/normas , China , Humanos , Estações do Ano , Fatores Socioeconômicos , Poluição da Água , Qualidade da Água
12.
Singapore Med J ; 61(1): 24-27, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31388686

RESUMO

INTRODUCTION: Vertical transmission of the hepatitis B virus (HBV) is higher in infants born to pregnant women with a higher HBV DNA viral load even if the infants complete both active and passive vaccination. Although antiviral treatment is recommended for pregnant women during the antenatal period to reduce the rate of vertical transmission, most of them decline treatment. METHODS: A decision tree was made to evaluate the costs and benefits involved when pregnant women either agreed or declined to take antiviral treatment during the antenatal period. The cost-effectiveness price was arrived at by multiplying the reduced vertical transmission rate with expenses of future medical care associated with vertical transmission. RESULTS: From an individual mother's perspective, it was not cost-effective to receive antenatal antiviral treatment given the observed medication price and transmission rate in Singapore. However, the health system asserts that the current price of antiviral treatment is already far below the cost-effectiveness level, even without the Ministry of Health subsidies. Additionally, the awareness and perception of pregnant women also impacted treatment decisions. CONCLUSION: By analysing the decision-making process, our result explained the current low uptake rates of antenatal antiviral treatment for HBV among pregnant women. We also concluded that from the health system's perspective, it was worth providing subsidies for perinatal antiviral treatment to prevent huge expenses generated in the future by chronic HBV complications.


Assuntos
Vacinas contra Hepatite B/uso terapêutico , Hepatite B/prevenção & controle , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , Complicações Infecciosas na Gravidez/prevenção & controle , Gestantes/psicologia , Vacinação/psicologia , Adulto , Atitude Frente a Saúde , Análise Custo-Benefício , Tomada de Decisões , Árvores de Decisões , Feminino , Hepatite B/economia , Vacinas contra Hepatite B/economia , Humanos , Recém-Nascido , Transmissão Vertical de Doenças Infecciosas/economia , Gravidez , Complicações Infecciosas na Gravidez/economia , Complicações Infecciosas na Gravidez/psicologia , Complicações Infecciosas na Gravidez/virologia , Singapura , Vacinação/economia , Carga Viral , Adulto Jovem
13.
Carbohydr Polym ; 195: 53-62, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29805008

RESUMO

Biopolymer produced from marine Athelia strain presented unique Pseudoplastic behaviors under extremely-high temperature and salinity conditions. Characteristic analysis with FT-IR spectroscopy, high performance liquid chromatography, 1H and 13C NMR and two-dimensional COSY and HMQC spectra showed the structure of ß-(1-6) glucans. Single-factor and orthogonal experiment design were used to optimize the yield, the maximum yield of the biopolymer was 28.32 g/L with 56.64% carbon conversion rate under optimized conditions. Economic investigation demonstrated that this novel biopolymer has great potential of commercialization with the competitive cost of $2896.04-5228.94 per ton for powder. Resistance factor and residual resistance factor were evaluated with core flooding experiments showed that this biopolymer had excellent performance of plugging capacity and profile modification, and indicating the great potential of application on heavy oil recovery.


Assuntos
Basidiomycota/metabolismo , Biopolímeros/biossíntese , Polissacarídeos Fúngicos/biossíntese , Microbiologia Industrial/métodos , Óleos/metabolismo , Basidiomycota/genética , Custos e Análise de Custo , Microbiologia Industrial/economia , Óleos/química
14.
PLoS One ; 5(3): e9182, 2010 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-20231879

RESUMO

Chemotaxis is defined as a behavior involving organisms sensing attractants or repellents and leading towards or away from them. Therefore, it is possible to reengineer chemotaxis network to control the movement of bacteria to our advantage. Understanding the design principles of chemotaxis pathway is a prerequisite and an important topic in synthetic biology. Here, we provide guidelines for chemotaxis pathway design by employing control theory and reverse engineering concept on pathway dynamic design. We first analyzed the mathematical models for two most important kinds of E. coli chemotaxis pathway-adaptive and non-adaptive pathways, and concluded that the control units of the pathway de facto function as a band-pass filter and a low-pass filter, respectively, by abstracting the frequency response properties of the pathways. The advantage of the band-pass filter is established, and we demonstrate how to tune the three key parameters of it-A (max amplification), omega(1) (down cut-off frequency) and omega(2) (up cut-off frequency) to optimize the chemotactic effect. Finally, we hypothesized a similar but simpler version of the dynamic pathway model based on the principles discovered and show that it leads to similar properties with native E. coli chemotactic behaviors. Our study provides an example of simulating and designing biological dynamics in silico and indicates how to make use of the native pathway's features in this process. Furthermore, the characteristics we discovered and tested through reverse engineering may help to understand the design principles of the pathway and promote the design of artificial chemotaxis pathways.


Assuntos
Quimiotaxia , Escherichia coli/metabolismo , Algoritmos , Fenômenos Fisiológicos Bacterianos , Ligantes , Cadeias de Markov , Modelos Biológicos , Modelos Estatísticos , Modelos Teóricos , Movimento , Fosforilação , Ligação Proteica , Engenharia de Proteínas
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