共查询到20条相似文献,搜索用时 31 毫秒
1.
Christopher G Lausted Arthur T Johnson William H Scott Monique M Johnson Karen M Coyne Derya C Coursey 《Biomedical engineering online》2006,5(1):29-6
Background
Maximum pressures developed by the respiratory muscles can indicate the health of the respiratory system, help to determine maximum respiratory flow rates, and contribute to respiratory power development. Past measurements of maximum pressures have been found to be inadequate for inclusion in some exercise models involving respiration. 相似文献2.
Claudia Trappetti Luciana Gualdi Lorenzo Di Meola Prashant Jain Cindy C Korir Paul Edmonds Francesco Iannelli Susanna Ricci Gianni Pozzi Marco R Oggioni 《BMC microbiology》2011,11(1):75
Background
Different models for biofilm in Streptococcus pneumoniae have been described in literature. To permit comparison of experimental data, we characterised the impact of the pneumococcal quorum-sensing competence system on biofilm formation in three models. For this scope, we used two microtiter and one continuous culture biofilm system. 相似文献3.
Background
Cognitive decline is a major threat to well being in later life. Change scores and regression based models have often been used for its investigation. Most methods used to describe cognitive decline assume individuals lose their cognitive abilities at a constant rate with time. The investigation of the parametric curve that best describes the process has been prevented by restrictions imposed by study design limitations and methodological considerations. We propose a comparison of parametric shapes that could be considered to describe the process of cognitive decline in late life. 相似文献4.
Background
Quantifying the robustness of biochemical models is important both for determining the validity of a natural system model and for designing reliable and robust synthetic biochemical networks. Several tools have been proposed in the literature. Unfortunately, multiparameter robustness analysis suffers from computational limitations. 相似文献5.
Tomoya Kitayama Ayako Kinoshita Masahiro Sugimoto Yoichi Nakayama Masaru Tomita 《Theoretical biology & medical modelling》2006,3(1):24
Background
In order to improve understanding of metabolic systems there have been attempts to construct S-system models from time courses. Conventionally, non-linear curve-fitting algorithms have been used for modelling, because of the non-linear properties of parameter estimation from time series. However, the huge iterative calculations required have hindered the development of large-scale metabolic pathway models. To solve this problem we propose a novel method involving power-law modelling of metabolic pathways from the Jacobian of the targeted system and the steady-state flux profiles by linearization of S-systems. 相似文献6.
Xavier Bailly Stefano Vanin Christine Chabasse Kenji Mizuguchi Serge N Vinogradov 《BMC evolutionary biology》2008,8(1):244
Background
Hemerythrins, are the non-heme, diiron binding respiratory proteins of brachiopods, priapulids and sipunculans; they are also found in annelids and bacteria, where their functions have not been fully elucidated. 相似文献7.
Background
Reliable estimates of disease burden associated with respiratory viruses are keys to deployment of preventive strategies such as vaccination and resource allocation. Such estimates are particularly needed in tropical and subtropical regions where some methods commonly used in temperate regions are not applicable. While a number of alternative approaches to assess the influenza associated disease burden have been recently reported, none of these models have been validated with virologically confirmed data. Even fewer methods have been developed for other common respiratory viruses such as respiratory syncytial virus (RSV), parainfluenza and adenovirus.Methods and Findings
We had recently conducted a prospective population-based study of virologically confirmed hospitalization for acute respiratory illnesses in persons <18 years residing in Hong Kong Island. Here we used this dataset to validate two commonly used models for estimation of influenza disease burden, namely the rate difference model and Poisson regression model, and also explored the applicability of these models to estimate the disease burden of other respiratory viruses. The Poisson regression models with different link functions all yielded estimates well correlated with the virologically confirmed influenza associated hospitalization, especially in children older than two years. The disease burden estimates for RSV, parainfluenza and adenovirus were less reliable with wide confidence intervals. The rate difference model was not applicable to RSV, parainfluenza and adenovirus and grossly underestimated the true burden of influenza associated hospitalization.Conclusion
The Poisson regression model generally produced satisfactory estimates in calculating the disease burden of respiratory viruses in a subtropical region such as Hong Kong. 相似文献8.
Erika G Meraz Homer Nazeran Carlos D Ramos Pat Nava Bill Diong Michael D Goldman 《Biomedical engineering online》2011,10(1):21-1
Background
Is Impulse Oscillometry System (IOS) a valuable tool to measure respiratory system function in Children?Asthma (A) is the most prevalent chronic respiratory disease in children. Therefore, early and accurate assessment of respiratory function is of tremendous clinical interest in diagnosis, monitoring and treatment of respiratory conditions in this subpopulation.IOS has been successfully used to measure lung function in children with a high degree of sensitivity and specificity to small airway impairments (SAI) and asthma. IOS measures of airway function and equivalent electrical circuit models of the human respiratory system have been developed to quantify the severity of these conditions. Previously, we have evaluated several known respiratory models based on the Mead's model and more parsimonious versions based on fitting IOS data known as extended RIC (eRIC) and augmented RIC (aRIC) models have emerged, which offer advantages over earlier models.Methods
IOS data from twenty-six children were collected and compared during pre-bronchodilation (pre-B) and post- bronchodilation (post-B) conditions over a period of 2 years.Results and Discussion
Are the IOS and model parameters capable of differentiating between healthy children and children with respiratory system distress?Children were classified into two main categories: Healthy (H) and Small Airway-Impaired (SAI). The IOS measures and respiratory model parameters analyzed differed consistently between H and SAI children. SAI children showed smaller trend of "growth" and larger trend of bronchodilator responses than H children.The two model parameters: peripheral compliance (Cp) and peripheral resistance (Rp) tracked IOS indices of small airway function well. Cp was a more sensitive index than Rp. Both eRIC and aRIC Cps and the IOS Reactance Area, AX, (also known as the "Goldman Triangle") showed good correlations.Conclusions
What are the most useful IOS and model parameters?In this work we demonstrate that IOS parameters such as resistance at 5 Hz (R5), frequency-dependence of resistance (fdR: R5-R20), reactance area (AX), and parameter estimates of respiratory system such as Cp and Rp provide sensitive indicators of lung function and have the capacity to differentiate between obstructed and non-obstructed airway conditions. They are also capable of demonstrating airway growth-related changes over a two-year period.We conclude that the IOS parameters AX and the eRIC model derived parameter Cp are the most reliable parameters to track lung function in children before and after bronchodilator and over a time period (2 years).Which model is more suitable for interpreting IOS data?IOS data are equally well-modelled by eRIC and aRIC models, based on the close correlations of their corresponding parameters - excluding upper airway shunt compliance. The eRIC model is a more parsimonious and equally powerful model in capturing the differences in IOS indices between SAI and H children. Therefore, it may be considered a clinically-preferred model of lung function.9.
Background
Analysis and design of complex systems benefit from mathematically tractable models, which are often derived by approximating a nonlinear system with an effective equivalent linear system. Biological oscillators with coupled positive and negative feedback loops, termed hysteresis or relaxation oscillators, are an important class of nonlinear systems and have been the subject of comprehensive computational studies. Analytical approximations have identified criteria for sustained oscillations, but have not linked the observed period and phase to compact formulas involving underlying molecular parameters. 相似文献10.
Statistical analysis of real-time PCR data 总被引:1,自引:0,他引:1
Background
Even though real-time PCR has been broadly applied in biomedical sciences, data processing procedures for the analysis of quantitative real-time PCR are still lacking; specifically in the realm of appropriate statistical treatment. Confidence interval and statistical significance considerations are not explicit in many of the current data analysis approaches. Based on the standard curve method and other useful data analysis methods, we present and compare four statistical approaches and models for the analysis of real-time PCR data. 相似文献11.
Background
Ventricular function has conventionally been characterized using indexes of systolic (contractile) or diastolic (relaxation/stiffness) function. Systolic indexes include maximum elastance or equivalently the end-systolic pressure volume relation and left ventricular ejection fraction. Diastolic indexes include the time constant of isovolumic relaxation - and the end-diastolic pressure-volume relation. Conceptualization of ventricular contraction/relaxation coupling presents a challenge when mechanical events of the cardiac cycle are depicted in conventional pressure, P, or volume, V, terms. Additional conceptual difficulty arises when ventricular/vascular coupling is considered using P, V variables. 相似文献12.
Background
Empirical binding models have previously been investigated for the energetics of protein complexation (ΔG models) and for the influence of mutations on complexation (i.e. differences between wild-type and mutant complexes, ΔΔG models). We construct binding models to directly compare these processes, which have generally been studied separately. 相似文献13.
José E San Miguel-Ruiz Angel R Maldonado-Soto José E García-Arrarás 《BMC developmental biology》2009,9(1):3-19
Background
Regeneration of neurons and fibers in the mammalian spinal cord has not been plausible, even though extensive studies have been made to understand the restrictive factors involved. New experimental models and strategies are necessary to determine how new nerve cells are generated and how fibers regrow and connect with their targets in adult animals. Non-vertebrate deuterostomes might provide some answers to these questions. Echinoderms, with their amazing regenerative capacities could serve as model systems; however, very few studies have been done to study the regeneration of their nervous system. 相似文献14.
Jan Krumsiek Sebastian Pölsterl Dominik M Wittmann Fabian J Theis 《BMC bioinformatics》2010,11(1):233
Background
Phenomenological information about regulatory interactions is frequently available and can be readily converted to Boolean models. Fully quantitative models, on the other hand, provide detailed insights into the precise dynamics of the underlying system. In order to connect discrete and continuous modeling approaches, methods for the conversion of Boolean systems into systems of ordinary differential equations have been developed recently. As biological interaction networks have steadily grown in size and complexity, a fully automated framework for the conversion process is desirable. 相似文献15.
Background
Sec8 is highly expressed in mammalian nervous systems and has been proposed to play a role in several aspects of neural development and function, including neurite outgrowth, calcium-dependent neurotransmitter secretion, trafficking of ionotropic glutamate receptors and regulation of neuronal microtubule assembly. However, these models have never been testedin vivo. Nervous system development and function have not been described after mutation ofsec8 in any organism. 相似文献16.
JF Yuan SJ Zhang O Jafer RA Furlong OE Chausiaux CA Sargent GH Zhang NA Affara 《BMC microbiology》2009,9(1):246
Background
Pseudorabies virus (PRV) is an alphaherpesviruses whose native host is pig. PRV infection mainly causes signs of central nervous system disorder in young pigs, and respiratory system diseases in the adult. 相似文献17.
Background
High frequency chest compression (HFCC) is a useful and popular therapy for clearing bronchial airways of excessive or thicker mucus. Our observation of respiratory airflow of a subject during use of HFCC showed the airflow oscillation by HFCC was strongly influenced by the nonlinearity of the respiratory system. We used a computational model-based approach to analyse the respiratory airflow during use of HFCC. 相似文献18.
Yi Sheng Chih-Cheng Lin Junming Yue Meena Sukhwani Jennifer J Shuttleworth Tianjiao Chu Kyle E Orwig 《BMC developmental biology》2010,10(1):17
Background
The tetracycline-inducible gene regulation system is a powerful tool that allows temporal and dose-dependent regulation of target transgene expression in vitro and in vivo. Several tetracycline-inducible transgenic mouse models have been described with ubiquitous or tissue-specific expression of tetracycline-transactivator (tTA), reverse tetracycline-transactivator (rtTA) or Tet repressor (TetR). Here we describe a Tet-On transgenic rat that ubiquitously expresses rtTA-M2 driven by the murine ROSA 26 promoter. 相似文献19.
Uladzimir U Karniychuk Marc Geldhof Merijn Vanhee Jan Van Doorsselaere Tamara A Saveleva Hans J Nauwynck 《BMC veterinary research》2010,6(1):30
Background
Porcine reproductive and respiratory syndrome virus (PRRSV) is divided into a European and North American genotype. East European PRRSV isolates have been found to be of the European genotype, but form different subtypes. In the present study, PRRSV was isolated from a Belarusian farm with reproductive and respiratory failure and designated "Lena". Analyses revealed that Lena is a new East European subtype 3 PRRSV isolate. The main purpose of this investigation was to study the pathogenesis and antigenic characteristics of PRRSV (Lena). 相似文献20.