Extended kalman filter for estimation of parameters in nonlinear state-space models of biochemical networks.

It is system dynamics that determines the function of cells, tissues and organisms. To develop mathematical models and estimate their parameters are an essential issue for studying dynamic behaviors of biological systems which include metabolic networks, genetic regulatory networks and signal transduction pathways, under perturbation of external stimuli. In general, biological dynamic systems are partially observed. Therefore, a natural way to model dynamic biological systems is to employ nonlinear state-space equations. Although statistical methods for parameter estimation of linear models in biological dynamic systems have been developed intensively in the recent years, the estimation of both states and parameters of nonlinear dynamic systems remains a challenging task. In this report, we apply extended Kalman Filter (EKF) to the estimation of both states and parameters of nonlinear state-space models. To evaluate the performance of the EKF for parameter estimation, we apply the EKF to a simulation dataset and two real datasets: JAK-STAT signal transduction pathway and Ras/Raf/MEK/ERK signaling transduction pathways datasets. The preliminary results show that EKF can accurately estimate the parameters and predict states in nonlinear state-space equations for modeling dynamic biochemical networks.

Genetic networks controlling retinal injury.

PURPOSE: The present study defines genomic loci underlying coordinate changes in gene expression following retinal injury. METHODS: A group of acute phase genes expressed in diverse nervous system tissues was defined by combining microarray results from injury studies from rat retina, brain, and spinal cord. Genomic loci regulating the brain expression of acute phase genes were identified using a panel of BXD recombinant inbred (RI) mouse strains. Candidate upstream regulators within a locus were defined using single nucleotide polymorphism databases and promoter motif databases. RESULTS: The acute phase response of rat retina, brain, and spinal cord was dominated by transcription factors. Three genomic loci control transcript expression of acute phase genes in brains of BXD RI mouse strains. One locus was identified on chromosome 12 and was highly correlated with the expression of classic acute phase genes. Within the locus we identified the inhibitor of DNA binding 2 (Id2) as a candidate upstream regulator. Id2 was upregulated as an acute phase transcript in injury models of rat retina, brain, and spinal cord. CONCLUSIONS: We defined a group of transcriptional changes associated with the retinal acute injury response. Using genetic linkage analysis of natural transcript variation, we identified regulatory loci and candidate regulators that control transcript levels of acute phase genes.

Saturday Morning Television Advertisements Aired on English and Spanish Language Networks along the Texas-Mexico Border

Objectives: The aim of this content analysis study is to characterize the TV advertisements aired to an at-risk child population along the Texas-Mexico border. Methods: We characterized the early Saturday morning TV advertisements aired by three broadcast network categories (U.S. English language, U.S. Spanish language, and Mexican Spanish language) in Spring 2010. The number, type (food related vs. non-food related), target audience, and persuasion tactics used were recorded. Advertised foods, based on nutrition content, were categorized as meeting or not meeting current dietary guidelines. Results: Most commercials were non-food related (82.7%, 397 of 480). The majority of the prepared foods (e.g., cereals, snacks, and drinks) advertised did not meet the current U.S. Dietary Guidelines. Additionally, nutrition content information was not available for many of the foods advertised on the Mexican Spanish language broadcast network category. Conclusions: For U.S. children at risk for obesity along the Texas-Mexico border exposure to TV food advertisements may result in the continuation of sedentary behavior as well as an increased consumption of foods of poor nutritional quality. An international regulatory effort to monitor and enforce the reduction of child-oriented food advertising is needed. Editors' Note: This article was submitted in response to the first issue of the Journal of Applied Research on Children: Latino Children.

'Reform' of the British national health service after the election of a labour government: Understanding the policy development process

The policy development process leading to the Labour government's white paper of December 1997—The new NHS: Modern, Dependable—is the focus of this project and the public policy development literature is used to aid in the understanding of this process. Policy makers who had been involved in the development of the white paper were interviewed in order to acquire a thorough understanding of who was involved in this process and how they produced the white paper. A theoretical framework is used that sorts policy development models into those that focus on knowledge and experience, and those which focus on politics and influence. This framework is central to understanding the evidence gathered from the individuals and associations that participated in this policy development process. The main research question to be asked in this project is to what extent do either of these sets of policy development models aid in understanding and explicating the process by which the Labour government's policies were developed. The interview evidence, along with published evidence, show that a clear pattern of policy change emerged from this policy development process, and the Knowledge-Experience and Politics-Influence policy making models both assist in understanding this process. The early stages of the policy development process were characterized as hierarchical and iterative, yet also very collaborative among those participating, with knowledge and experience being quite prevalent. At every point in the process, however, informal networks of political influence were used and noted to be quite prevalent by all of the individuals interviewed. The later stages of the process then became increasingly noninclusive, with decisions made by a select group of internal and external policy makers. These policy making models became an important tool with which to understand the policy development process. This Knowledge-Experience and Politics-Influence dichotomy of policy development models could therefore be useful in analyzing other types of policy development. ^

Interrelationships between the structural and functional aspects of social relationships, comorbidity and health related quality of life in breast cancer survivors

It is widely acknowledged in theoretical and empirical literature that social relationships, comprising of structural measures (social networks) and functional measures (perceived social support) have an undeniable effect on health outcomes. However, the actual mechanism of this effect has yet to be clearly understood or explicated. In addition, comorbidity is found to adversely affect social relationships and health related quality of life (a valued outcome measure in cancer patients and survivors). ^ This cross sectional study uses selected baseline data (N=3088) from the Women's Healthy Eating and Living (WHEL) study. Lisrel 8.72 was used for the latent variable structural equation modeling. Due to the ordinal nature of the data, Weighted Least Squares (WLS) method of estimation using Asymptotic Distribution Free covariance matrices was chosen for this analysis. The primary exogenous predictor variables are Social Networks and Comorbidity; Perceived Social Support is the endogenous predictor variable. Three dimensions of HRQoL, physical, mental and satisfaction with current quality of life were the outcome variables. ^ This study hypothesizes and tests the mechanism and pathways between comorbidity, social relationships and HRQoL using latent variable structural equation modeling. After testing the measurement models of social networks and perceived social support, a structural model hypothesizing associations between the latent exogenous and endogenous variables was tested. The results of the study after listwise deletion (N=2131) mostly confirmed the hypothesized relationships (TLI, CFI >0.95, RMSEA = 0.05, p=0.15). Comorbidity was adversely associated with all three HRQoL outcomes. Strong ties were negatively associated with perceived social support; social network had a strong positive association with perceived social support, which served as a mediator between social networks and HRQoL. Mental health quality of life was the most adversely affected by the predictor variables. ^ This study is a preliminary look at the integration of structural and functional measures of social relationships, comorbidity and three HRQoL indicators using LVSEM. Developing stronger social networks and forming supportive relationships is beneficial for health outcomes such as HRQoL of cancer survivors. Thus, the medical community treating cancer survivors as well as the survivor's social networks need to be informed and cognizant of these possible relationships. ^

Culture and the social context of health inequalities

There has been a great deal of interest and debate recently concerning the linkages between inequality and health cross-nationally. Exposures to social and health inequalities likely vary as a consequence of different cultural contexts. It is important to guide research by a theoretical perspective that includes cultural and social contexts cross-nationally. If inequality affects health only under specific cultural conditions, this could explain why some of the literature that compares different societies finds no evidence of a relationship between inequality and health in certain countries. A theoretical framework is presented that combines sociological theory with constructs from cultural psychology in order to identify pathways that might lead from cultural dimensions to health inequalities. Three analyses are carried out. The first analysis explores whether there is a relationship between cultural dimensions at the societal level and self-rated health at the individual level. The findings suggest that different cultural norms at the societal level can produce both social and health inequalities, but the effects on health may differ depending on the socio-cultural context. The second analysis tests the hypothesis that health is affected by the density of social networks in a society, levels of societal trust, and inequality. The results suggest that commonly used measures of social cohesion and inequality may have both contextual and compositional effects on health in a large number of countries, and that societal measures of social cohesion and inequality interact with individual measures of social participation, trust, and income, moderating their effects on health. The third analysis explores whether value systems associated with vertical individualist societies may lead to health disparities because of their stigmatizing effects. I test the hypothesis that, within vertical individualist societies, subjective well-being will be affected by a social context where competition and the Protestant work ethic are valued, mediated by inequality. The hypothesis was not supported by the available cross-national data, most likely because of inadequate measures, missing data, and the small sample of vertical individualist countries. The overall findings demonstrate that cultural differences are important contextual factors that should not be overlooked when examining the causes of health inequalities. ^

Achieving effective biosurveillance with the Nationwide Health Information Network

The federal government is currently developing the Nationwide Health Information Network (NHIN). Described as a “network of networks,” the NHIN seeks to provide a nationwide, interoperable health information infrastructure that will securely connect consumers with those involved in health care. As part of the national health information technology (HIT) agenda, the NHIN aims to improve individual and population health by enabling health information to follow the consumer, be available for clinical decision-making, and support important public health measures such as biosurveillance. While the NHIN promises to improve clinical care to individuals and to reduce U.S. health care system costs overall, this electronic environment presents novel challenges for protecting individually identifiable health information. A major barrier to achieving public trust in the NHIN is the development of, and adherence to, a consistent and coordinated approach to privacy and security of health information. This paper will analyze the policy framework for electronic health information exchange with the NHIN. This exercise will demonstrate that the current policy is an effective framework for achieving effective biosurveillance with the NHIN. ^

Social network size and perceived network sufficiency as predictors of perceived health status

This study focused on the relationship between social network size (number of friends and relatives), perceived sufficiency of the network and self-rated health utilizing data from the National Survey of Personal Health Practices and Consequences, 1979. For men neither perceived sufficiency nor number of relatives were associated with self-rated health status. The number of friends was positively associated with health status. For women perceived network sufficiency was positively and significantly related to health status, independent of network size. The number of friends and relatives was not associated with self-rated health status. The sociodemographic variables accounted for most of the explained variance in health status for both males and females. Social networks may hold different meanings for women and men, and may require qualitative as well as quantitative analysis. There may have been insufficient variance in the major variables to produce meaningful results. ^

Social support, health status and health services utilization among the noninstitutionalized elderly: An analysis of the Supplement on Aging to the 1984 national health interview survey

The association between Social Support, Health Status, and Health Services Utilization of the elderly, was explored based on the analysis of data from the Supplement on Aging to the National Health Interview Survey, 1984 (N = 11,497) using a modified framework of Aday and Andersen's Expanded Behavioral Model. The results suggested that Social Support as operationalized in this study was an independent determinant of the use of health services. The quantity of social activities and the use of community services were the two most consistent determinants across different types of health services use.^ The effects of social support on the use of health services were broken down into three components to facilitate explanations of the mechanisms through which social support operated. The Predisposing and Enabling component of Social Support had independent, although not uniform, effects on the use of health services. Only slight substitute effects of social support were detected. These included the substitution of the use of senior centers for longer stay in the hospital and the substitution of help with IADL problems for the use of formal home care services.^ The effect of financial support on the use of health services was found to be different for middle and low income populations. This differential effect was also found for the presence of intimate networks, the frequencies of interaction with children and the perceived availability of support among urban/rural, male/female and white/non-white subgroups.^ The study also suggested that the selection of appropriate Health Status measures should be based on the type of Health Services Utilization in which a researcher is interested. The level of physical function limitation and role activity limitation were the two most consistent predictors of the volume of physician visits, number of hospital days, and average length of stay in the hospital during the past year.^ Some alternative hypotheses were also raised and evaluated, when possible. The impacts of the complex sample design, the reliability and validity of the measures and other limitations of this analysis were also discussed. Finally, a revised framework was proposed and discussed based on the analysis. Some policy implications and suggestions for future study were also presented. ^

The impact of social support networks on compliance with hypertensive therapeutic regimens among noninstitutionalized black adults

A conceptual framework based on the Health Belief Model was proposed which identified those factors most significant in the prediction of compliance behavior. The hypothesized model was applied to analyze the effects of sociodemographic characteristics, self-assessed health status, and social support networks on compliance with antihypertensive regimens, focusing on black adults.^ The study population was selected from the National Health and Examination Survey II (NHANES II) which produced a sample of 3,957 eligible persons 35-74 years of age.^ The study addressed the following research questions: (a) what is the relationship between demographic variables and self-assessed health status, (b) what is the relationship between social support network and self-assessed health status, (c) what is the compliance, (d) what factors, e.g., demographic characteristics, social support network, self-assessed health status, are most related to compliance, and (e) does the effect of these factors on compliance differ between black and white adults?^ The results of the study found that blacks: (a) had poorer health than whites, and education and income were significantly related to self-assessed health status, (b) the stronger social support networks of blacks, the better their health status, and (c) older blacks and those in poorer health were more likely to comply with recommended treatment. The hypothesized conceptual model for the prediction of compliance behavior was partially substantiated for both blacks and whites.^ Implications for the application of the conceptual model are also discussed. ^

Understanding mental illness in Nigeria: Bringing culture and traditional medicine into mental health policy

One of the major challenges in treating mental illness in Nigeria is that the health care facilities and mental health care professionals are not enough in number or well equipped to handle the burden of mental illness. There are several barriers to treatment for individual Nigerians which include the following: such as the lack of understanding of the root causes of mental illness, lack of financial support to get mental treatment, lack of social support (family, friends, neighbors), the fear of stigmatization concerning being labeled as mentally ill or being in association with the mentally ill, and the consultation of traditional native healers who may be unknowingly prolonging illness, rather than addressing and treating them due to lack of formal education and standardization of their treatments. Another barrier is the non-health nature of the mental health services in Nigeria. Traditional healers are essentially the mental health system. The elderly, women, and children are the most vulnerable groups in times of strife and hardships. Their mental well-being must be taken into account as well as their special needs in times of personal or societal crisis. ^ Nigerian mental health policy is geared toward forming a mental health system, but in actuality only a mental illness care system is the observed result of the policy. The government of Nigeria has drafted a mental health policy, yet its actual implementation into the Nigerian health infrastructure and society waits to be materialized. The limited health legislation or policy implementations tend to favor those who have access to these urban areas and the facilities' health services. Nigerians living in rural areas are at a disadvantage; many of them may not even be aware of services available to help them understand and treat mental illness. Perhaps, government driven health interventions geared toward mental illness in rural areas would reach an underserved Nigerians and Africans in general. Issues with political instability and limited infrastructure often hinder crucial financial resources and legislation from reaching the people that are truly in need of governmental leadership in regards to mental health policy.^ Traditional healers are a severely untapped resource in the treatment of mental illness within the Nigerian population. They are abundant within Nigerian communities and are meeting a real need for the mentally ill. However, much can be done to remove the barriers that prevent the integration of traditional healers within the mental health system and improve the quality of care they administer within the population. Mental illness is almost exclusively coped with through traditional medicine practices. Mobilization and education from each strata of Nigerian society and government as well as input from the medical community can improve how traditional medicine is utilized as a treatment for clinical illness and help alleviate the heavy burden of mental illness in Nigeria. Currently, there is no existing policy making structure for a working mental health system in Nigeria, and traditional healers are not taken into account in any formulation of mental health policy. Advocacy for mental illness is severely inadequate due to fear of stigmatization, with no formally recognized national of regional mental health association.^