The observation of variation in substitution rates among lineages has led to (1) a general rejection of the molecular clock model, and (2) the suggestion that a number of biological characteristics of organisms can cause rate variation. Accurate estimates of rate variation, and thus accurate inferences regarding the causes of rate variation, depend on accurate estimates of substitution rates. However, theory suggests that even when the substitution process is clock-like, variable numbers of substitutions can occur among lineages because the substitution process is stochastic. Furthermore, substitution rates along lineages can be misestimated, particularly when multiple substitutions occur at some sites. Although these potential causes of error in rate estimation are well understood in theory, such error has not been examined in detail; consequently, empirical studies that estimate rate variation among lineages have been unable to determine whether their results could be impacted by estimation error.To evaluate the extent to which error in rate estimation could erroneously suggest rate variation among lineages, we examined rate variation estimated for datasets simulated under a molecular clock on trees with equal and variable branch lengths. Thus, any apparent rate variation in these datasets reflects error in rate estimation rather than true differences in the underlying substitution process. We observed substantial rate variation among lineages in our simulations; however, we did not observe rate variation when average substitution rates were compared between different clades.Our results confirm previous theoretical work suggesting that observations of among lineage rate variation in empirical data may be due to the stochastic substitution process and error in the estimation of substitution rates, rather than true differences in the underlying substitution process among lineages. However, conclusions regarding rate variation drawn from rates averaged across multiple branches are likely due to real, systematic variation in rates between groups. There is significant interest in estimating rates of gene evolution Across species, rate variation in orthologous genes has been attributed to differences in the biology of different organisms. For example, species with shorter generation times may have higher substitution rates because more rounds of DNA replication in germs cells produce more mutations per unit time Before suggesting a link between biological processes and variation in substitution rates, it is necessary to determine whether rate variation occurs in a dataset. Methods of measuring rate variation fall into two broad categories: (1) descriptive statistics of rate variation among lineages, clades, or other subsets of the tree, and (2) statistical tests for deviation from a molecular clock. Descriptive statistics of rate variation include the overall range of variation and the standard deviation of rates across the tree All measures of rate variation, and all inferences linking rate variation to some aspect of organismal biology, depend on accurate estimates of substitution rates. The independent process of substitution at different sites results in the expectation that, when the substitution process is clock-like, the number of substitutions on a branch will be drawn from a Poisson distribution Another challenge associated with rate estimation is the underestimation of the number of substitutions along some branches, as a result of multiple substitutions at some sites, particularly as phylogenetic distance (i.e. branch length) increases Although these potential sources of error in rate estimation have been described previously, their cumulative effects on estimates of rate variation among lineages have not been examined in detail. Thus, studies that link substitution rate variation to particular biological processes have not been able to consider whether error in rate variation estimation affects their conclusions. In this study, we simulated datasets under a molecular clock and estimated (1) substitution rates for each lineage, and (2) substitution rate variation among lineages. Thus, any rate variation we observe reflects error in rate estimation, including both stochastic variation due to the Poisson process, and incorrect estimates of the number of substitutions along lineages; our analyses allow us to differentiate between these two sources of error and avoid confounding error with true variation in the substitution process. We used datasets of both equal and unequal branch lengths simulated using both simple and more realistic substitution models  was <2-fold for all simulated datasets see .Trees with unequal-length branches more closely approximate empirical datasets; thus, we simulated datasets on the 27-taxon plethodontid salamander phylogeny of Mueller et al. Because we estimated substantial rate variation among lineages using simulated clock-like data based on parameters from empirical plethodontid data, we compared these results to the rate variation estimated from the original empirical data We observed substantial variation in estimated rates of substitution, both in Bayesian and ML frameworks, when considering all branches across trees simulated under an enforced molecular clock. Simulations were conducted using a clock-like substitution process; therefore, this observed rate variation must be due to error in rate estimation, both as a result of the stochastic substitution process producing different numbers of substitutions than expected along lineages, and misestimation of rates due to uncounted substitutions. This variation provides an example of the potential for error in estimates of rate variation for empirical datasets. Levels of rate variation observed for datasets simulated with realistic parameters were even greater than those for simple 8-taxon simulations, suggesting that the level of error in simple simulations provides a minimum for potential error in empirical datasets.Estimates of rate variation derived from empirical data in plethodontid salamanders were less than those derived from comparable datasets simulated under an enforced molecular clock, suggesting that the empirically-estimated rate variation may reflect error rather than true differences in the underlying biological substitution process. In addition to the stochastic variation and rate misestimation error that are the focus of this study, the node-density effect can cause error in variation Our results suggest that some conclusions of other studies based on apparent variation in substitution rates may be based, at least in part, on error in rate estimation. For example, inferences based on the estimated rate of a single lineage, such as an exceptionally high rate Error in estimating rate variation can significantly impact phylogeny and divergence date estimation; thus, the observation of rate variation in many datasets has led to the development of substitution models attempting to accommodate such rate variation Previous observations of rate variation among lineages resulted in the suggestion that divergence dates among clades could be estimated accurately by using mean substitution rates for multiple species within each clade Our observations of rate variation across branches, despite a clock-like substitution process in simulations, are consistent with previously suggested sources of error in rate estimation. The rate variation we observed for simple datasets simulated on phylogenies with shorter branches was likely due to the probabilistic substitution process, which generates a set of branch lengths that follow a Poisson distribution, even when the rate of the underlying substitution process is constant. However, the difference between the actual and expected number of substitutions produced by the probabilistic substitution process does not account for the estimated rate variation for phylogenies with longer branches. As branch length increases, the effect of the standard deviation in the Poisson distribution decreases in comparison to the mean when considering expected rate variation. Thus, we expect rate variation estimated as a result of the stochastic substitution process to decrease as branch lengths increase. In contrast, our results show an increase in mean rate variation as branch length increases  and we aIn simulations, the substitution process conforms to a specified model; thus, the imprecise fit of the model to the data that can cause rate estimation error for empirical data In contrast to rate variation estimates across all branches of a tree, averaged rates across clades or branch depths showed little difference in estimated rates in either Bayesian or ML frameworks for the majority of branch lengths. Thus, error in estimates of rates on individual branches was not sufficient to mislead comparisons of rates among clades or among different tree depths in simulations. This lack of difference in rates results partly from the Poisson distribution of the actual number of substitutions around the expected number; when multiple samples (i.e. rates estimated from different branches) from a single distribution are averaged, no rate variation is expected. It also suggests that methodological error in rate estimation is equally distributed around the mean estimated rate. Similarly, we observed little difference in estimated rates between the two major clades of plethodontid salamanders when using empirical data. These similar rates between clades are also consistent with the possibility, suggested by the comparison of rate variation across all branches for empirical and simulated data, that observed rate variation in this dataset reflects error in rate estimation.These results suggest that conclusions based on average rates across multiple lineages are unlikely to be affected by error in rate estimation. Thus, comparisons of average substitution rates between clades suggesting a faster rate for one clade are likely accurate Because of the substantial variation in substitution rates we observed in our data, we might have expected to reject a molecular clock for each dataset; this was not the case. However, as noted by Li In summary, we suggest that estimates of among-lineage rate variation are prone to error. However, the impacts of such error on conclusions drawn from empirical datasets depend on the measure of rate variation used in analysis. We suggest that conclusions based on (1) the overall range of rate variation across all branches in a tree, and/or (2) rates estimated on individual branches should be drawn with caution. However, because error in rate estimation produces normally distributed rate estimates, conclusions based on rates averaged across multiple branches are likely not affected.We used two types of simulations to test the extent to which error in substitution rate estimation can lead to overall error in rate variation estimation: (1) simple trees of equal-length branches, and (2) more realistic trees of mixed-length branches. Using trees with equal-length branches avoided the confounding factor of different levels of multiple substitutions per site expected when comparing long and short branches. However, trees with mixed-length branches are more similar to those that might be observed in empirical datasets. In both cases, there was no rate variation in the simulation process and the tree was ultrametric. By using a simulation approach, error in rate estimation can be isolated from the confounding problem of error in substitution model estimation present in empirical datasets.Branch lengths for each dataset were estimated in both Bayesian  across all branches (i.e. the maximum estimated branch length divided by the minimum estimated branch length); (2) between branch depths (i.e. average estimated branch length for depth 2 branches divided by average estimated branch length for depth 1 branches ); and 3). ComparOne of our goals was to distinguish erroneously estimated rate variation resulting from the stochastic substitution process from that resulting from misestimation of substitution rates. We did this in the following way, based on characteristics of the Poisson distribution: for each set of simple simulations, 100 datasets with 13 branches each yielded in an expectation of 65 branches with estimated rates not within two standard deviations of the mean. If such branches are equally distributed among datasets, at least 35 datasets should have estimated rate variation less than (μ+2σ)/(μ−2σ); when this is not the case, we infer that error in rate estimation is present and causing more extensive rate variation than expected based on the stochastic substitution process alone.The significance of the difference in rates between clades or depths was determined based on whether error bars of one standard deviation overlapped. Because a common method of determining whether the substitution process is clock-like is to compare results with and without the molecular clock enforced, we also tested whether the molecular clock could be rejected by any of our datasets. We conducted these tests using (1) Bayes factor comparisons for Bayesian analyses with and without the clock enforced (a Bayes factor >10 was considered significant) To further describe the distribution of rates estimated for each dataset, we tested each of the 2200 distributions for normality atp6, cob, cox3, nad1, and nad2)  and the divergence dates estimated by Mueller The second set of datasets was simulated on a more realistic tree of 27 taxa based on the plethodontid salamander phylogeny of Mueller et al. atp6; 4-fold for cob; 2.9-fold for cox3; 4.4-fold for nad1; and 3.9-fold for nad2Our analyses of apparent rate variation in clock-like datasets provide a measure of error that might exist in estimates of rate variation from empirical data. More specifically, if rate variation for empirical data falls within the rate variation erroneously estimated for comparable clock-like data, this would suggest that the empirical rate variation is due to error in rate estimation rather than true differences among lineages in the underlying biological substitution process. Mueller


There is an increasing body of published cost-utility analyses of health interventions which we sought to draw together to inform research and policy.To achieve consistency in costing base and policy context, study scope was limited to Australian-based cost-effectiveness analyses. Through a comprehensive literature review we identified 245 health care interventions that met our study criteria.The median cost-effectiveness ratio was A$18,100  per QALY/DALY/LY . Some modalities tended to perform worse, such as vaccinations and diagnostics , than others such as allied health, lifestyle, in-patient interventions . Interventions addressing some diseases such as diabetes and impaired glucose tolerance or alcohol and drug dependence tended to perform well . Interventions targeting younger persons < 25 years  tended to perform less well than those targeting adults > 25 years . However, there was also substantial variation in the cost effectiveness of individual interventions within and across all categories.For any given condition, modality or setting there are likely to be examples of interventions that are cost effective and cost ineffective. It will be important for decision makers to make decisions based on the individual merits of an intervention rather than rely on broad generalisations. Further evaluation is warranted to address gaps in the literature and to ensure that evaluations are performed in areas with greatest potential benefit. Because resources are limited not all potentially beneficial services can be funded. Choices must be made in allocating scarce resources. Economic evaluation can help inform resource allocation choices by comparing costs and consequences of two or more alternatives. Comparisons between interventions will be more robust where they are country specific, at least in terms of input costs, which differ considerably between countries. To date Australian economic evaluations have not been systematically described, appraised or explored, except for decisions of the PBAC  between 1991 to 1996[The aim of the current paper is to describe and explore Australian published economic evaluations and to analyse the distribution of published cost-effectiveness ratios. This analysis will determine whether there is any identifiable pattern in published cost-effectiveness ratios. The results will potentially to assist policy makers with resource allocation decisions and will identify gaps in the types of interventions evaluated.The Medline OVID database from 1966 to present was searched in April 2005 for relevant studies using key words for "cost effectiveness" and "economic evaluation" combined with the key word "Australia". In addition websites of Australian health economics centres and government health departments were searched [See Additional file Studies of economic analysis of lifesaving or quality enhancing "health" interventions were eligible for inclusion, defined as broadly fitting within the context of the health care system. An initial selection of potentially relevant articles was made by one reviewer (KD). This selection was broad and overly inclusively.The following inclusion criteria were then applied by two reviewers (KD and DM) independently to each full text article initially identified as potentially relevant. Consensus was reached by discussion.• Resources were estimated in Australian dollars.• The economic evaluation presented as cost per LY saved, death averted, QALY gained or DALY averted, or this could be simply calculated from the figures provided.• The article was published in English.• The article was not a duplicate publication. The most complete or recent work by the authors was selected for inclusion with supplementary information retrieved from other reports. Publication on similar interventions by different authors did not class as duplicate.• The study was primary research. Review articles citing the work of others were excluded, although the reference lists were searched for additional relevant publications.An assessment of the quality of the economic evaluations was performed by one reviewer (KD) following study inclusion. The quality criteria reflect items taken from a framework for quality of cost-effectiveness models developed by Sculpher et al. This inThe strength of underlying evidence was rated strong  or limited . The comparator chosen for the evaluation was rated either as appropriate (described and justified) or inappropriate (not described or justified). Measurement of costs was rated as appropriate  or inappropriate. Each evaluation was rated as having sensitivity analysis performed or not performed.Where articles included analysis of more than one intervention, data were extracted for each separate intervention. Data abstraction was performed by one reviewer (KD) with checking of key variables by a second reviewer (LS). The following types of variables were extracted: the characteristics of the target disease and patients, details of the intervention, nature of publication and study methodology, and estimated performance. Policy relevant variables, including funding status were separately ascertained Table . These vCost per LY/QALY/DALY estimates were reviewed and recalculated where necessary to ensure each referred to marginal costs and benefits. Estimates were standardised by translating values into June 2005 estimates using the health component of the CPI. If a stIn the event that a reference year was not reported for costs, we used the publication year minus two to reflect the usual delay in publishing original research. Categorisation of the type of intervention, type of patients and results was possible for all studies included in the review. The only sources of missing data were discount rate, time horizon and length of intervention benefit which were purely descriptive variables.Data were described using medians and interquartile ranges for continuous data and proportions for categorical data. The pattern of cost-effectiveness results across the 245 interventions was explored through a combination of descriptive and regression analyses. Ordinary least squares regression was undertaken to identify variables that might explain variation in the cost per LY/QALY/DALY estimates. Ordered logit regression was undertaken to identify variables that might explain variation in the cost per LY/QALY/DALY group. All regressions adjusted for intra-cluster correlation present in the data because data on multiple interventions were drawn from many of the papers included in our review. We used the robust Huber/White sandwich estimator to adjust population-average models for intra-cluster correlation, yielding robust standard errors suitable for calculating confidence intervals around estimated regression coefficients[All potentially relevant intervention and publication characteristics listed in Table The Medline search lead to 912 results, of which 42 (4.6%) were identified as potentially relevant through screening titles and abstracts. An additional 11 papers or reports were identified through key author searches, 9 through reviewing bibliographies of identified articles and 52 through the website searches. A total of 114 full text documents were examined for inclusion in this review  were more costly and less effective than their comparators and were therefore dominated, 21 interventions (8%) were both more effective and cheaper than their comparator and thus dominant. Figure th and 75th percentile cost-effectiveness ratio of each category and reports statistical significance. Statistically significantly higher median incremental cost-effectiveness ratios (ICERs) (performed worse) were found for interventions targeted at children/youth compared to adults, for medical interventions compared with lifestyle interventions, vaccinations compared to all other modalities, evaluations where downstream cost impacts were not included. In relation to quality variables, the small number of evaluations that did not use an appropriate comparator and did not meet minimum standards of quality performed better. Evaluations based on strong quality evidence (strength of evidence) with regards to treatment effect were associated with similar median cost-effectiveness estimates as evaluations with limited quality evidence. Those that were associated with statistically significantly lower median ICERs, included the following:Table • non-medical interventions  compared to medical ,• treatment interventions compared to diagnosis/screening/prevention,• interventions where the individual was able to reduce their own risk of disease or injury,• interventions where the condition was cause by patients' own behaviour, and• interventions that were partially funded  rather than fully or not funded all.Figures That said, the extent of variation in the data is such that there were examples of highly cost-effective and cost-ineffective care within most categories.Linear regression analysis using the enter method was undertaken to identify variables from those listed in Table Interpretation of the parameter estimates is straightforward. Pharmaceuticals  and interventions primarily benefiting persons aged between 25 and 65 years would generally have a lower cost per LY/QALY/DALY than an intervention benefiting older or younger age groups. The quality of evaluation also made a significant contribution to the regression such that a failure to conduct sensitivity analysis was associated with a lower cost per LY/QALY/DALY ratio. Interventions targeting persons able to reduce their own risk of death/disease and interventions that are partially funded out of patient contributions would also generally have a higher cost per LY/QALY/DALY than otherwise. It is, however, important to note that the regression explains only a small proportion of the overall variance in cost per LY/QALY/DALY group.We also undertook an ordered logit regression to identify variables from those listed in Table Through this study, data are now available on the economic performance, expressed in Australian costs, of a wide range of interventions that address different health problems, using alternative modalities and intervening at various stages in disease development. The identification of a large number of interventions (37%) reported at less than A$10,000 per LY/QALY/DALY (including 8% that were dominant), which is below any putative funding threshold is important in itself. It raises issues about the relationship between cost effectiveness and funding decisions and the appropriateness of current funding thresholds. These matters are explored elsewhere.We identified some interesting findings by category, for example that interventions targeted at children were generally less cost-effective than those targeting adults. This is perhaps not surprisingly, especially in relation to chronic disease prevention where benefits are typically delayed at least into middle age. Similarly, 'population approaches' were not found to be more cost effective than more targeted approaches, which may reflect very large differences in effectiveness. It would be interesting to explore the especially good and especially poor performance of some classes of intervention; such as the poor performance of diagnostics and vaccinations or the favourable performance of allied health and lifestyle interventions and those addressing diabetes and drug/alcohol abuse. That said category averages should be interpreted with care due to the identified wide variation in cost effectiveness with no 'magic bullet' answers to resource allocation. In terms of policy decision it would be best to assess each potential intervention on its own merits rather than rely on broad generalisations -10.We also note that this is the first review of publicly available Australian economic evaluations, which provides valuable information to guide policy and research, but also highlights the continued need for improvement in quality of economic evaluation and transparency. This type of exercise, summarising the cost effectiveness of different interventions and subgroups has been proposed as a useful priority setting task , with prThe limitations of this review include a reliance on publicly available evaluation reports. While it is possible that some studies were missed through our original search focus on Medline, a later search of the HEED  database using the same search terms identified no additional studies.With regards to quality, this review has inherited the quality of the original work, which we have attempted to describe. Interestingly, the pattern of cost effectiveness of interventions where evaluations were based on limited non-RCT evidence did not differ from those based on stronger RCT evidence. There is no reason to presume that potential biases will systematically impact on cost-effectiveness results.A significant limitation of this work is that the economic evaluation methods varied significantly between interventions thus impacting on the comparisons made. This is illustrated in identified differences in discounting, perspective, time horizons, choice of comparators and strength of underlying evidence. The strength of this work therefore lies in the rich description of existing evaluations. Ideally all outcome measures would be identical to assist with comparisons. However, we would contend that there is enough common ground between the outcome measures QALY, DALY and LY for cost-effectiveness ratios to be sensibly compared. Evaluations reporting cost per LYs gained may have generally focused on length of life because quality of life was not expected to vary greatly relative to the impact on mortality. Despite differences in the concept of 'health' underlying adjustments for morbidity using the QALY or the DALY, these do include both mortality and morbidity effects. However, we acknowledge that this is a potential source of error. We were limited in that study resources only permitted one person to perform data extraction of variables. This is unlikely to have lead to bias against single interventions or group of interventions, but may have involved a particular interpretation of variables extracted across all studies.The list of interventions and associated cost-effectiveness ratios is reported [See Additional file The cost effectiveness of Australian Pharmaceuticals has been previously reported in a review of PBAC  decision making from 1991 to 1996[In the US a large scale review exercise was undertaken of 500 life saving interventions across the areas of health, transport and environment. Tengs eA more recent review was conducted of cost-utility analyses in the United States (494 studies and 1433 cost-effectiveness ratios),13,15. TPublished cost-effectiveness results may reflect the research interests or priorities of researchers or industry, the visibility of certain diseases, the strength of advocacy and industry backing rather than the health needs of society. The resThis exercise should be repeated for other countries, as findings are likely to vary according to the delivery arrangements and costing structure of different health systems. There is the opportunity using datasets such as this for a more in depth analysis of the quality of economic evaluation, which could be used to inform evaluator training and guide methodological advances. It would also be possible to compare the quality of evaluations over time to assess improvements.Another application of this work is to explore the extent to which economic evaluation informs policy making. Our recent extension to this work  addresseA$: Australian Dollar; ABS: Australian Bureau of Statistics; AIHW: Australian Institute of Health and Welfare; AR-DRG: Australian refined diagnosis-related group; CPI: consumer price index; DALY: disability-adjusted life year; DM: Duncan Mortimer; DRG: diagnosis-related group; HEED: NHS Economic Evaluation Database; HYE: healthy-year equivalent; HTA: health technology assessment; ICC: intra-cluster correlation coefficient; ICER: incremental cost-effectiveness ratio; KD: Kim Dalziel; LS: Leonie Segal; LY: life-year; MSAC: Medical Services Advisory Committee; PBAC: Pharmaceutical Benefits Advisory Committee; PBS: Pharmaceutical Benefits Schedule; RCT: randomised controlled trial; SD: standard deviation; US: United States of America; US$: United States Dollar.The authors declare that they have no competing interests.KD participated in the design of the study, coordinated the data collection, participated in the data analysis and interpretation of results, and drafted the manuscript. LS participated in the design of the study and data collection, and suggested edits and revisions to the manuscript. DM participated in the data collection, data analysis and interpretation of results, and suggested edits and revisions to the manuscript. All authors read and approved the final manuscript.APPENDIX 1_CERA. A copy of the first appendix detailing the search strategy used in the systematic reviewClick here for fileAPPENDIX 2_CERA. A copy of the second appendix which provides a list of the 245 Australian health interventions included in the systematic review along with an estimate of their cost effectiveness.Click here for file


Mechanisms underlying obesity-related metabolic disorders are poorly understood. Samuel Virtue and Antonio Vidal-Puig explore the evidence for an emerging hypothesis that attributes metabolic complications not to obesity per se, but to an individual's capacity for adipose tissue expandability. The spiralling increase in obesity rates in the Western and developing worlds has brought with it a host of related metabolic complications including diabetes, dyslipidaemia, cardiovascular complications, and cancer. Whereas obesity itself presents its own independent health problems—such as sleep apnoea or psychological issues—the vast majority of obesity-related mortality is caused by these secondary metabolic complications. The link between obesity and such complications as insulin resistance is well established on a population level but poorly understood mechanistically. Efforts to tackle the obesity epidemic through public health initiatives and drugs have so far been notable for their lack of success. With little prospect for halting the obesity epidemic, treatment of its associated diseases becomes of paramount importance both for public health and associated costs .On an epidemiological level, there is a strong correlation between obesity and diabetes; in fact, for every kilogram gained on a population level, diabetes rates increase linearly . The linThe Adipokine Hypothesisadipokines). In the obese state, adipose tissue secretes proportionally more adipokines that cause insulin resistance and fewer that promote insulin sensitivity.Obesity leads to an alteration in the profile of hormones secreted by adipose tissue  White Adipose Tissue is located underneath the skin but outside the abdominal cavity. In terms of whole-organism metabolic sensitivity, SC adipose tissue is considered either beneficial or at worse inert.Visceral White Adipose Tissue is located within the abdominal cavity and has been associated with a high risk of metabolic disease.The adipose tissue expandability hypothesis suggests that the insulin resistance found in lipodystrophic and obese individuals is caused by the same pathogenic mechanism of impaired adipose tissue expansion capacity, even if the underlying cause and degree of impairment in adipose tissue expansion may be very different. While the idea that lean and very obese people may develop insulin resistance through the same pathogenic paradigm of exhaustion of adipose tissue expandability is controversial, it is actually well supported in rodent models.Several mouse studies have demonstrated that defective adipose tissue function causes severe insulin resistance ,10. The To test if the adipose tissue expandability hypothesis can be applied to obesity-induced diabetes, it is necessary to investigate obese mouse models with subtle reductions in adipose tissue expansion. Two recent mouse studies ,12 have Based on the adipose tissue expandability hypothesis, it should be possible to become massively obese without metabolic complications, so long as new adipose tissue can be made. Until recently there was no mouse model of such a state. The recent publication by Kim et al.  of a mouAssaying adipose tissue expandability in humans is far more difficult than in mice; however, some indirect evidence does support the concept that once adipose tissue capacity for lipid storage is exhausted, metabolic complications ensue. Evidence for a role for adipose tissue in lipid homeostasis comes from studies of human adipose tissue function in lean and obese humans. These studies showed that adipose tissue from obese individuals was unable to appropriately take up lipids in the postprandial state and that insulin did not impair fatty acid release as efficiently as in lean individuals, suggesting that failure in lipid buffering in adipose tissue is also a result of excessive expansion of adipose tissue. The failure to buffer lipid appropriately in obese individuals leads to elevated fatty acids and triglycerides, producing a lipotoxic lipid profile that we believe is a fundamental pathogenic mechanism leading to the Metabolic Syndrome. One possible explanation for this buffering failure is that the adipose tissue has become saturated, or reached the limit of its storage capacity, in obese individuals .The adipose tissue expandability hypothesis is further supported by studies that have used TZDs to treat non-alchoholic fatty liver disease (NAFL) and non-alcoholic steatohepatitis (NASH). These studies have demonstrated excellent efficacy of TZDs in terms of reduced hepatic lipid content. Interestingly, TZDs promote adipose tissue expansion and, in multiple studies, lead to weight gain. As increased body mass index (BMI) is a risk factor for NASH and NAFL, it is striking that these potent lipogenic agents actually reduce hepatic lipid accumulation ,16. The The adipose tissue expansion hypothesis should be considered one of several major hypotheses to explain the link between obesity and the Metabolic Syndrome see . PerhapsThe second major hypothesis regarding how obesity leads to diabetes regards the role of adipose tissue as an endocrine organ. Adipose tissue is known to secrete multiple hormones, of which leptin is perhaps the most famous. Leptin was cloned in 1994 (and has subsequently been demonstrated to play important roles in the control of body weight and insulin sensitivity). Over the past 14 years, many more adipokines have been identified including pro-insulin sensitising adipokines such as adiponectin and adipokines that have been implicated in causing insulin resistance, such as visfatin, retinol binding protein 4, and resistin. As discussed above, adipose tissue can also secrete chemokines and cytokines. The idea that obesity leads to altered adipokine profiles that can subsequently cause systemic insulin resistance is well supported. Again, the adipokine hypothesis is not contradictory to the adipose tissue expandability hypothesis. Larger adipocytes found in the obese state have altered profiles of adipokine secretion. Furthermore, insulin resistance can cause alterations in adipokine secretion; for example, 4-month-old ob/ob mice have far less adiponectin than wild-type littermates do . The datSo far, this Essay has discussed adipose tissue in general terms; however, in humans, there are distinct differences between adipose tissue depots dependent on their location. Different adipose tissue depots have distinct gene expression profiles . FurtherEvidence to support the concept that visceral and subcutaneous depots have different intrinsic adipose tissue expansion capacities comes from studies demonstrating that preadipocytes from subcutaneous depots differentiate more rapidly than those from omental depots and are more responsive to TZDs ,29. The Although the different metabolic properties of visceral and subcutaneous fat may be related to the anatomical location of the fat depots, there is some evidence to suggest that there may be intrinsic cell-autonomous differences between subcutaneous and visceral adipose tissue. Perhaps the most compelling evidence for intrinsic metabolic properties of subcutaneous and visceral adipose tissue depots come from the work of Tran et al., demonstrating that transplanting subcutaneous fat into the abdominal cavity of mice improved the metabolic profile when compared to either visceral-to-visceral fat transplants, visceral-to–subcutaneous, or subcutaneous-to-visceral transplants .A final aspect regarding different adipose tissue depots is why some individuals develop increased adipose tissue in abdominal depots and others in visceral depots. It is likely that the interactions between intrinsic properties of the depots  coupled Although epidemiologically the risk of diabetes, for example, increases linearly with increased body weight, the adipose tissue expandability hypothesis suggests that this may not be the case in an individual. Rather, once an individual reaches their maximal adipose tissue mass, then metabolic complications ensue, suggesting that individuals would go from metabolically normal to metabolically compromised in a relatively small weight window . When avThe concept that the primary mechanism linking obesity to metabolic complications is a failure in the capacity of adipose tissue to expand to accommodate excess nutrients has several clinical and scientific implications. Scientifically, it creates a unified framework to help to explain how diabetes can occur in both obese and lipodystrophic states. It also integrates explanations of how changes in lipid handling and adipocyte size may interact to lead to inflammation, dyslipidaemia, and ultimately to diabetes. However, further work remains to validate the adipose tissue expandability hypothesis and how it may relate obesity to diabetes.The recent study of Spalding et al.  demonstrThe finding that adipocyte number is stabilized in adults raises many questions about how adipocyte formation and life span are regulated. If birth and death rates of adipocytes are maintained so closely, then there must be a homeostatic mechanism that allows the control of birth and death of adipocytes. But how is the formation of new adipocytes regulated? Is it at the level of commitment of mesenchymal stem cells to preadipocytes, preadipocyte hyperplasia, or differentiation of preadipocytes to mature adipocytes? Clearly a large number of questions regarding how adipose tissue plasticity is regulated remain, and understanding these processes will be essential if new drugs that target adipose tissue expandability are to be developed.Clinically, the adipose tissue expandability hypothesis has several implications. First, it explains how pharmacological agents that promote adipose tissue expansion may be suitable for the treatment of a variety of disorders, including diabetes, NASH, NAFL, and most recently dyslipidaemia. Studies demonstrating that TZDs may be suitable for the treatment of a wide variety of metabolic disorders beyond diabetes have unfortunately coincided with concerns over the safety of this class of drugs, stressing the need for new drugs that target adipose tissue expansion.Finally, the adipose tissue expansion hypothesis may allow for the design of better obesity treatment regimes, particularly with respect to personalised weight loss programs. If there is a “set point” for body weight and adipose tissue expansion beyond which an individual becomes metabolically compromised, then tailoring a weight loss program to an individual's threshold of metabolic complications, rather than to general therapeutically-unachievable targets based on population studies, may result in better compliance and therefore treatment efficacy .


Parasites, as with the vast majority of organisms, are dependent on iron. Pathogens must compete directly with the host for this essential trace metal, which is sequestered within host proteins and inorganic chelates. Not surprisingly, pathogenic prokaryotes and eukaryotic parasites have diverse adaptations to exploit host iron resources. How pathogenic bacteria scavenge host iron is well characterized and is reasonably well known for a few parasitic protozoa, but is poorly understood for metazoan parasites. Strategies of iron acquisition by schistosomes are examined here, with emphasis on possible mechanisms of iron absorption from host serum iron transporters or from digested haem. Elucidation of these metabolic mechanisms could lead to the development of new interventions for the control of schistosomiasis and other helminth diseases. The recent release of the genome sequence information of a range of parasites has provided a plethora of tools for the study of parasite biology 2+ (ferrous) and Fe3+ (ferric). This property has enabled eukaryotes and prokaryotes to use iron for many crucial biological reactions Iron contributes ∼5% of the Earth's crust, and is a trace requirement for virtually all prokaryotic and eukaryotic organisms Tight regulation of iron in mammalian hosts presents an obstacle to invading pathogens, which also require this essential element. Hosts bind iron in proteins or inorganic chelates, and present an iron-restricted environment to pathogenic bacteria and parasites. Indeed, hosts ‘withhold’ iron as an integral strategy of innate immunity 3+, and production of specific ligands to entrap and strip host iron carriers  For intracellular parasites, such as lic iron . It is kRhodnius prolixus, for example, processes haem, not by the classical pathways resulting in biliverdin (BV) IX, carbon monoxide (CO) and iron, but by unique reactions resulting in dicysteinyl-BV IXgamma, CO and iron Apart from the well characterized iron metabolism pathways of mammals Schistosoma mansoni. Rao and colleagues de novo synthesis or salvage is an unresolved and intriguing question. It also remains to be determined if helminths can salvage iron from haem through action of HO.Roundworms and flatworms possess haem-containing proteins, but are said to lack the biosynthetic machinery for haem There is solid evidence that iron is used by schistosomes for development and reproduction. Schistosomes sequester iron in the gastrodermal lumen in vitroS. mansoni expresses two isoforms of a divalent metal transporter (DMT) with significant sequence similarity to the mammalian ferrous iron-uptake protein, DMT1  in vitro studies of iron uptake in schistosomes conducted by Clemens and Basch, which suggested that iron uptake is surface-mediated and most probably from iron transporters, such as Tf, which are abundant in host serum 2+, which is relatively insoluble at physiological pH Tf and non-Tf-bound iron (NTBI) stimulate the growth of schistosomula in silico evidence that haem is catabolized to release iron, because there are no ESTs representing HO in the published schistosome EST databases Schistosoma japonicumRenewed interest in haem acquisition in metazoan parasites raises the question whether schistosomes can use host haem for synthesis of haemoproteins or as a source of iron. The gastrodermis is enriched in haem by virtue of haemoglobinolytic pathways S. japonicum Fer-1 in experimental schistosomiasis S. mansoni show significant overall homology to mammalian DMTs It is clear that iron is essential for growth and maintenance of schistosomes. Iron-uptake transporters and receptors are implicated in pathogen virulence and immunogenicity In vitro, iron chelators halt the growth of schistosomes and protozoan parasites Another strategy for parasite control might include the use of chemotherapeutics targeted at iron uptake and regulation. The artemisinin drug family has shown to be effective against both schistosomiasis and malaria Although the amount of data on iron assimilation in schistosomes is growing, there remain significant gaps and inconsistencies in our knowledge . In addi


Protein interactions are central to most biological processes, and are currently the subject of great interest. Yet despite the many recently developed methods forinteraction discovery, little attention has been paid to one of the best sources ofdata: complexes of known three-dimensional (3D) structure. Here we discuss howsuch complexes can be used to study and predict protein interactions and complexes,and to interrogate interaction networks proposed by methods such as two-hybridscreens or affinity purifications.


A hypothesis is proposed that tumour lysis may be an important factor affecting blood levels of CEA. This has been explored in an experimental study with a model tumour system, consisting of immune-deprived mice bearing human CEA-producing tumours. Using agents such as irradiation, chemotherapeutic drugs, diphtheria toxin and techniques such as cryosurgery, it has been shown that tumour lysis is important when it is both rapid and extensive. The extent to which this may occur in patients remains uncertain, except in rare instances of dramatic response of malignant disease to treatment.


In this paper we review recent models that provide adaptive explanations for animal personalities: individual differences in behaviour (or suites of correlated behaviours) that are consistent over time or contexts. We start by briefly discussing patterns of variation in behaviour that have been documented in natural populations. In the main part of the paper we discuss models for personality differences that (i) explain animal personalities as adaptive behavioural responses to differences in state, (ii) investigate how feedbacks between state and behaviour can stabilize initial differences among individuals and (iii) provide adaptive explanations for animal personalities that are not based on state differences. Throughout, we focus on two basic questions. First, what is the basic conceptual idea underlying the model? Second, what are the key assumptions and predictions of the model? We conclude by discussing empirical features of personalities that have not yet been addressed by formal modelling. While this paper is primarily intended to guide empiricists through current adaptive theory, thereby stimulating empirical tests of these models, we hope it also inspires theoreticians to address aspects of personalities that have received little attention up to now. Parus major), for example, differ consistently in whole suites of correlated traits, with more aggressive individuals also tending to be more explorative towards novel objects and unfamiliar environments than less aggressive ones . We then review formal  models for adaptive personality differences (§3), where we focus on two main questions. First, what is the basic conceptual idea underlying the model? Second, what are the key assumptions and predictions of the model? We conclude by discussing features of consistent individual differences that have not yet been addressed by models (§4). The aim of this review is to guide empiricists through recent models for adaptive animal personalities and stimulate tests of the assumptions and predictions of these models.2.responsiveness). In all cases, consistency refers to both stability over time (in terms of date or age) and/or contexts .The empirical literature on animal personality has reported three types of behavioural patterns that require adaptive explanation in the context of animal personality variation  for each of three individuals , where lines depict their reaction norms . In many populations of three-spined stickleback (Gasterosteus aculeatus), for example, activity, aggressiveness, exploratory behaviour and boldness are positively correlated across individuals (a) across two or more behavioural traits (b), i.e. the between-individual  correlations . In laboratory rodents, for example, certain individuals adjust their aggressiveness with social context, whereas others do not (figure 1a). In Ural Owls , for example, mothers that are on average aggressive in nest defence against humans show greater plasticity in aggressiveness when compared with mothers that are less aggressive  State-dependent personality models are centred around the idea that individuals differ in state, where state can be defined broadly as those features of an organism  that affect the balance between the costs and benefits of its behavioural actions . For a fb.Explaining personality variation via differences in state leaves us with two basic problems : first, To work out whether a state-dependent model explains behavioural variation associated with personalities in real animals, it would be useful to design experimental studies to test model predictions and assumptions tables  and 2. TIn many study systems, experimental approaches might not be feasible. In such cases, initial support for state-dependent models would have to come from studies that investigate the direction, sign and strength of covariation between state variables and behavioural traits within a population. For example, State-dependent personality variation can also be studied by assessing whether the amount of interindividual variation in behaviour can be predicted based on the amount of interindividual variation in state. For example, the extent of individual differentiation in those behaviours that contribute to growth-survival trade-offs in the model of We conclude this section by stressing that, to date, few empirical studies exist that have explicitly tested predictions derived from state-dependent personality models (but see (b)inherently stable, either because they are very costly (e.g. time-consuming) or even impossible to change, other state variables are much more labile . The idea of positive feedbacks is attractive because even minor initial differences in either state or behaviour can be amplified and stabilized through such feedback. Positive feedbacks thus provide a potentially powerful explanatory framework for animal personalities associated with labile state differences.Feedback mechanisms between labile states and behaviour might provide such an explanation : the stanegative feedbacks tend to erode initial differences in state.It should be stressed that feedbacks between state and behaviour need not always reinforce initial differences: state differences might give rise to behavioural differences, which in turn act to decrease initial differences in state. Individuals with low reserves (state), for example, might show a high foraging intensity to avoid starvation and thus increase their reserves. Such Several models have addressed the dynamic feedback between labile state and behaviour , and we (i)Individuals with low energy reserves are expected to be bolder in a foraging context than those with higher reserves because they have to avoid the risk of starvation. This relation between energy reserves and boldness involves a negative feedback that erodes initial differences in state (and thus behaviour): individuals with low reserves are bolder than individuals with high reserves; they consequently acquire more reserves, thus leading to the convergence of states and therefore behaviour among individuals over time .However, this need not always be the case. (ii)Individuals often perform better with increased experience , and proWhile these verbal ideas are well known, they have rarely been investigated in formal models. One recent example is provided by (iii)The asset-protection principle  provideset al. At first sight it may seem that asset protection involves a negative feedback that erodes differences in assets over time . Individ(iv)(c)Up to now our discussion focussed on models that are based on state differences. However, adaptive personality differences need not always reflect state differences among individuals . We here(i)Esox lucius) ((ii)et al. Natural populations typically harbour substantial amounts of variation (e.g. due to mutations). A series of recent models have shown that the amount of variation present in a population may have substantial effects on the expected outcome of evolution 4.How successful have theoreticians been in explaining and predicting patterns of individual differences in behaviour observed in natural populations? And what is still to be done? In our view, the current set of adaptive models should be regarded as a first step—much remains to be done.(a)Our review illustrates that the majority of current explanations for animal personalities are based on state differences among individuals. Several state variables have been investigated . Many ot(b)et al. Empiricists are now starting to understand how key ecological variables  are related to the presence (or absence) and structure of animal personalities in natural populations ((d)a), and we believe that future research should address this issue more explicitly. Furthermore, data from real animals show that behavioural variation is repeatable only over short time spans in certain species a), e.g. aggressive types are less plastic than non-aggressive ones (elevation of a reaction norm) and level of behavioural plasticity (the slope of a reaction norm). Such an approach essentially treats differences between individuals in their behavioural consistency as potentially meaningful et al.  variation in personality axes other than the aggressiveness–boldness syndrome, (ii) the links between ecological factors (like predation risk) and the presence and structure of personality variation, (iii) individual differences in behavioural plasticity, (iv) heritable versus environmentally determined personality variation and (v) conditions favouring personality variation not associated with variation in states.


The clinical experience recently reported with epidermal growth factor receptor (EGFR)-targeting drugs confirms the synergistic interactions observed between these compounds and conventional cytotoxic agents, which were previously established at the preclinical stage. There are, however, examples of major gaps between the bench and the bedside. Particularly demonstrative is the failure of the tyrosine kinase inhibitors (TKIs) (gefitinib and erlotinib) combined with chemotherapy in pretreated nonsmall cell lung cancer patients. These discrepancies can be due to several factors such as the methodology used to evaluate TKI plus cytotoxic agent combinations in preclinical models and the insufficient consideration given to the importance of the drug sequences for the tested combinations. Recent advances in understanding the biologic basis of acquired resistance to these agents have great potential to improve their clinical effectiveness. The purpose of this review is to critically examine the experimental conditions of the preclinical background for anti-EGFR drug–cytotoxic agent combinations and to attempt to explain the gap between clinical observations and preclinical data. The epidermal growth factor receptor (EGFR) is present in many cell types and can be considered as one of the best-characterised ligand-receptor systems . Epiderm1/S phase arrest, predominantly by suppression of G1/S-related cyclins and upregulation of the CDK inhibitor p27KIP1  reached similar conclusions when combining ZD1839 and taxanes, whereas associations with gemcitabine or vinorelbine led to more contrasting results. When combining gemcitabine and PKI 166, On the basis of current knowledge, there is no apparent distinction between TKIs and mAbs regarding their propensity to trigger, in the majority of cases, synergistic cytotoxic interactions with chemotherapeutic agents or irradiation. To a great extent this synergy can be attributed to the well-identified impact of EGFR-targeting drugs on cell division, apoptosis, angiogenesis and DNA repair (see above). In addition, the occurrence of cross-resistance is infrequent as the cellular targets and mechanisms of action of cytotoxic drugs and EGFR-targeting therapeutics are different. It must be stressed, however, that there are few, if any, experimental studies designed to thoroughly explore the different anticancer agents, class by class, in association with EGFR-targeting drugs and using appropriate methods of analysis . An exception is the study by In a number of cases, preclinical studies on EGFR targeting combined with cytotoxic drugs have been confirmed clinically, the most convincing instance being the therapeutic success achieved by the cetuximab–irinotecan association in irinotecan-refractory advanced colorectal cancer patients . Particuin vitro studies analysing the effects of combining EGFR-targeting drugs and chemotherapeutic compounds have been performed using the Chou and Talalay method. However, application of this method to cytostatic drugs such as those targeting EGFR may limit the significance of their final conclusion. This is mainly because, unlike true cytotoxic dose–response curves, cell proliferation inhibition leads to incomplete dose–effect curves  with IC50 values (defined as the drug concentration at the inflexion point) in the μM range. These concentrations are well above the pharmacologically relevant concentrations, reflecting a partial dependency of tumour cell lines to EGFR signalling. Only very rare EGF-addicted cell lines, such as A431, with a particularly high EGFR expression can give a complete dose–effect curve with an anti-EGFR drug. Of note, the Chou and Talalay model is also not applicable for the examination of tumour growth in vivo, in immunodeficient mice for instance. Thus, a number of in vivo studies testing combinations between anti-EGFR drugs and chemotherapeutic agents have concluded that synergistic interactions have occurred without the application of a specific statistical tool to calculate the final combined effects. In experiments combining cetuximab and irinotecan, To evaluate quantitatively the results of drug combinations, in vivo combination studies is the fact that conclusions are often drawn from one or two xenograft models with a fixed schedule. A convincing illustration is provided by the paclitaxel–gefitinib combination re-examined by 1 growth arrest of EGFR-dependent tumour cells may, following continuous administration, attenuate the effects of tubulin inhibitors – such as paclitaxel – which act primarily during mitosis. From gefitinib–paclitaxel combination studies on tumour xenograft models, they found that, in contrast to continuous administration of gefitinib, 2 days of gefitinib before paclitaxel was a most effective treatment giving significantly greater tumour regression and more frequent complete responses than the other schedule. in vivo experiments showed a schedule-dependent efficacy of gefitinib with a better efficacy when gefitinib was administered after the cytotoxic agent, that is, in combination with cisplatin on a murine hepatocellular carcinoma . Several groups from Europe and the United States have reported that the absence of K-Ras mutation was a condition necessary to obtain a clinical response to the association between cetuximab and irinotecan in irinotecan refractory patients  , the chemotherapy and targeted therapy combination approach is still a viable clinical research paradigm . Future Preclinical sequencing data are encouraging and will hopefully translate to the clinical setting. Appropriately designed clinical trials are required to define the optimum dose, schedule and sequence for these agents in combination with conventional therapies. Several clinical studies are ongoing or planned to examine sequential dosing regimens of erlotinib or gefitinib with chemotherapy in patients with various solid tumour types. The sequential approach will be tested in a US intergroup phase III study in which patients will be randomly assigned to gefitinib or placebo following chemoradiotherapy and consolidation docetaxel in patients with inoperable stage III NSCLC.Further translational studies including examination of molecular biomarkers such as gene-expression profiling, will help us to identify critical markers and allow us to select the patients most likely to benefit from therapy with TKIs. The complexity of the ErbB signalling network and the significance of various activated downstream markers remain under intense investigation with regard to potential prognostic and predictive value.The next clinical studies with EGFR-targeting agents should be designed with a strong translational research component to address several key questions, such as which patients are most likely to have a therapeutic benefit, what are the potential predictive factors of response or resistance to these agents and what are the best strategies for their combination with conventional and/or other targeted anticancer treatments.


Parents are integral to the implementation of obesity prevention and management recommendations for children. Exploration of barriers to and facilitators of parental decisions to adopt obesity prevention recommendations will inform future efforts to reduce childhood obesity.We conducted 4 focus groups  among a total of 19 parents of overweight (BMI ≥ 85th percentile) children aged 5-17 years. The main discussion focused on 7 common obesity prevention recommendations: reducing television (TV) watching, removing TV from child's bedroom, increasing physically active games, participating in community or school-based athletics, walking to school, walking more in general, and eating less fast food. Parents were asked to discuss what factors would make each recommendation more difficult (barriers) or easier (facilitators) to follow. Participants were also asked about the relative importance of economic (time and dollar costs/savings) barriers and facilitators if these were not brought into the discussion unprompted.Parents identified many barriers but few facilitators to adopting obesity prevention recommendations for their children. Members of all groups identified economic barriers (time and dollar costs) among a variety of pertinent barriers, although the discussion of dollar costs often required prompting. Parents cited other barriers including child preference, difficulty with changing habits, lack of information, lack of transportation, difficulty with monitoring child behavior, need for assistance from family members, parity with other family members, and neighborhood walking safety. Facilitators identified included access to physical activity programs, availability of alternatives to fast food and TV which are acceptable to the child, enlisting outside support, dietary information, involving the child, setting limits, making behavior changes gradually, and parental change in shopping behaviors and own eating behaviors.Parents identify numerous barriers to adopting obesity prevention recommendations, most notably child and family preferences and resistance to change, but also economic barriers. Intervention programs should consider the context of family priorities and how to overcome barriers and make use of relevant facilitators during program development. Childhood obesity is a prominent public health concern that is associated with an increased risk of cardiovascular disease, diabetes, some cancers, depression, discrimination and weight-related bias, and other morbidities . The shoParents control many aspects of the nutrition and physical activity environment that contribute to a child's health-related behaviors -10. HoweEconomic considerations, such as the high cost of nutritious foods and affordability of junk foods and fast foods, are commonly assumed determinants of food choice, in part because low-income families exhibit among the highest prevalence of childhood obesity in the U.S. . In consAn emerging literature is focusing on the economics of obesity in adults, but there has been less focus on the economics of childhood obesity. MacInnis & Rausser suggest a role for energy-dense processed foods, which have become less expensive, in contributing to childhood obesity or risk of obesity . A relatObesity prevention and management recommendations for children involve changes in parental behavior. As such, understanding parental decision-making related to adopting recommendations is critical and could inform future efforts to reduce childhood obesity. For example, information about parental barriers and facilitators could lead to obesity interventions that are tailored to maximize parental compliance.The objective of this study was to explore, through the use of qualitative methods, barriers and facilitators that influence parenting behaviors and decisions that relate to child food choices, activities, and other behaviors that could affect a child's risk of obesity. We focused especially on economic barriers, including both time and dollar costs, an understudied yet potentially salient barrier. Focus groups are conducive to identifying constructs of potential interest for future research and in determining whether non-economic barriers generate as much discussion as economic ones.We held four focus groups in Boston, MA, during October and November 2007: two in English and two in Spanish. We recruited parents of overweight children (BMI-for-age ≥ 85th percentile) aged 5-17 years attending the Preventive Cardiology clinic at Children's Hospital Boston or one of two weight management clinics at the hospital, One Step Ahead and Optimal Weight for Life (n = 19). Three pairs of the English-speaking participants in one focus group were married partners; therefore, data relate to 16 children. Focus group size ranges from 2 to 7 parents. Additional demographic data about the parent or the family were not collected at the focus groups.Focus groups lasted two hours. Parents received a $40 gift card incentive for participating in the focus groups. Dinner was provided at each focus group, as was a parking or taxi voucher. Participants completed written informed consent prior to the start of the focus group. The study protocol was approved by the Institutional Review Boards of Children's Hospital Boston and Harvard Pilgrim Health Care.A professional focus group facilitator (non-physician), who was bilingual in Spanish and English, conducted all four focus groups. The group facilitator used a semi-structured interview guide for the focus groups that began with an ice-breaker activity and a brief warm-up exercise. The main discussion focused on common obesity prevention recommendations selected by the authors: reducing TV watching time, removing TV from child's bedroom, increasing time spent playing physically active games, participating in community or school-based athletics, walking to and from school, walking more in general, and eating fewer fast food meals. Parents were asked to assess how difficult or easy each type of advice was for them to follow and to discuss what factors would make each type of advice more difficult (barriers) or easier (facilitators) to implement. Participants were also asked about the relative importance of economic (time and dollar costs/savings) barriers and facilitators if these were not brought into the discussion unprompted.We audiotaped and transcribed all focus groups to facilitate analysis and translated Spanish groups into English during transcription. Data were then transcribed into a Microsoft Word table with columns for focus group identifier, theme code, speaker ID, speaker comment and chronological sequence number . We condWe completed a topic by topic thematic analysis across focus groups within each population segment, defined as English-speaking and Spanish-speaking. Comparison tables with six columns, one for theme code, one for theme description, and one each for the four focus groups, were created and notations were made whenever one or more speakers in each focus group voiced a specific theme. After completing these notations for both English and Spanish speaking focus groups, themes were re-ordered for each focus group major theme in the comparison table such that subthemes that were voiced more frequently occur in an earlier row of the table. For each theme grouping across the four focus groups, we completed a comparative analysis and comparative cross-population segment thematic analysis.Validation was done after preliminary coding. All similarly coded text was reviewed to ensure that text that was not representative of the category definition was not included. Where errors were detected, the inappropriate text was recoded as an instance of the more appropriate theme and regrouped with text representing the corrected theme for data reduction.During data reduction, a table was created with one column per each of the four focus groups and one row for each theme code. In each cell, the number of participants within each focus group who explicitly mentioned that particular theme or subtheme in a similar way was recorded along with the participants' initials so that multiple similar responses from the same participant were not overcounted. Themes could then be prioritized by frequency of mentions both within and across focus groups.When asked about the importance of healthy weight compared to other childhood health issues during the warm-up exercise, some parents felt that child safety and academic performance were of higher priority than obesity prevention. Parents went on to identify various barriers and facilitators to adopting obesity prevention recommendations throughout the focus group discussion Table . AlthougThe barriers most frequently voiced regarding reducing time watching TV related to monitoring/time costs. After being asked what their children do when they are not watching TV at home, 2 parents in one focus group responded "driving me crazy" and one parent responded "fighting with his little sister". The barriers most frequently voiced regarding removing TVs from a child's bedroom related to difficulty with changing habits ("They've had TV since they've had their own room") and parity with other family members The barriers most frequently voiced regarding increasing physical activity related to time costs , lack of information , lack of transportation , child preference , safety , dollar costs , and the need for assistance from family members . The barrier most frequently voiced related to participating in school/community-based sports was child preference .The barriers most frequently voiced regarding walking to school related to practicality/time cost  and safety . The barrier most frequently voiced regarding walking more in general was child preference .."), and time costs .The barriers most frequently voiced regarding eating less fast food related to the need for assistance from other family members , child preference , dollar costs , and difficulty with changing habits (hard to change child's whole diet at once).In general, far fewer facilitators than barriers were identified for the obesity prevention recommendations. The facilitator most frequently voiced for reducing time watching TV was the availability of alternative activities. For the recommendation to remove TV from child's bedroom, the most frequently voiced facilitator related to early limit setting (tell child they cannot have a TV before they become teenagers). The facilitators most frequently voiced regarding increasing physical activity included availability of acceptable alternatives  and enlisting outside support . The most frequent facilitator about increasing participation in school/community-based sports was access . For reducing fast food, facilitators most frequently voiced included information about dollar costs  and parental behavior change (parents have to stop taking kids to fast food restaurants and buying fast food as takeout). The facilitators related to providing a healthier diet included parental behavior change , involve the child , limit setting ("I don't give them options."), and making behavior changes gradually .Parents in all groups voiced cultural or inherited family beliefs/behaviors about food. Parents in the Spanish-speaking groups indicated that country of origin may influence food choices. Cultural issues regarding the perceptions of weight were voiced only in the Spanish-speaking groups. These included beliefs that being fat or large is "pretty" and that thinness is related to sickness. Parents in the Spanish-speaking groups said that grandparents don't believe that excess weight is unhealthy ("In my house the fatter one was the prettier one.").Economic considerations relating to both dollar and time costs were voiced as barriers to implementing several types of advice. However, parents cited non-economic barriers and time cost barriers more frequently in the focus group discussion than dollar cost barriers and dollar cost barriers were sometimes identified only after prompting. Economic barriers were sometimes cited by parents in conjunction with other barriers .We asked parents in two focus groups how their lives would have to change in order to implement nutrition and physical activity recommendations. Changes that would necessitate time costs were identified. These included cutting back on work/study time to allow parents who worked or attended school to be home more to monitor child eating behaviors and spend more time with them .Parents in this study identified numerous barriers and some facilitators to adopting obesity prevention recommendations. Barriers such as child resistance due to preference for existing behaviors and family member-related barriers were common. Parents acknowledged that expecting all family members to adopt recommendations was a considerable obstacle. Parents cited difficulties related to changing their own behaviors (such removing TV from their bedroom) and expressed ambivalence about enforcing recommendations that they themselves do not follow. Parents within the focus groups acknowledged that successful obesity prevention requires making family-based changes. Parents indicated that other family members may not support their efforts to adopt changes related to their child's weight and identified conflicting dietary needs of other children as a barrier, again highlighting the importance of the acceptability of behavior change within the context of the family and household decision-making model. Parents identified few facilitators to implementing recommendations. Parents recognized that changing their own eating habits and shopping habits would help facilitate their child's adherence to recommendations and acknowledged the role of parenting skills such as limit setting. Parents indicated that access to physical activity programs and the availability of alternatives to fast food and TV which are acceptable to the child would facilitate adherence.Parents identified time cost barriers such as time required for transportation, to prepare healthy foods, to allow for participation in physical activity programs, and for behavior monitoring, more frequently than dollar cost barriers. Although parents identified dollar costs as barriers in all groups, they were not cited as the most important barriers. This may reflect the relative importance of dollar cost barriers or may have resulted because discussions of finances may be considered too sensitive or personal to be brought up without prompting. Further, dollar costs are not integral to some behavior changes such as removing the TV from the child's bedroom and walking to school so should not be a universally cited barrier. Additional research in this area should include individual survey research in which respondents may feel more comfortable discussing sensitive topics such as financial considerations. The frequency with which dollar costs are cited may also suggest that the influence of other barriers, such as child preference or family member-related barriers, dominate decisions about implementing recommendations. For example, parents may be less willing to make changes that involve time or dollar costs if their children are highly resistant to the changes.This study was subject to some limitations. Due to recruiting challenges, the size of the focus groups varied (from 2 to 7 participants), the sample of Spanish-speaking parents was smaller than the sample of English-speaking parents, and the groups consisted of parents of children of all ages . The small sample size limits the analysis of our findings as they may not be representative of the barriers/facilitators faced by all parents. Further, detailed demographic data about the parent and the family such as parental BMI and family size were not collected. Thus, differences in parental response based on parental or family characteristics were not assessed. Additional research assessing barriers among a large and varied sample of parents is warranted to explore the relationship between family characteristics and barriers faced. In addition, this study explored barriers and facilitators to implementing 7 specific types of obesity prevention recommendations. Although these represent common recommendations made by pediatricians, other possible recommendations related to nutrition and physical activity for overweight children were not included.Given the limited number of studies that have considered economic factors contributing to physical activity and nutrition choices for children, this study adds to the literature by identifying both time and dollar costs as potential barriers to the adoption of obesity prevention. Further, this study identified that barriers related to all family members including children, parents, and other family members may prevail over these economic barriers. Future studies should consider the relative importance of the types of identified barriers and how barriers interact. In addition, ongoing research which examines how the entire family participates in decisions about nutrition and physical is needed. Interventions aimed at preventing obesity in childhood should be designed to help parents overcome barriers identified. For example, parents should be given support for changing their own behaviors and parents should be equipped to address issues such as child resistance and lack of support from other family members.The barriers identified in this study were numerous and varied, suggesting that parents face a unique combination of barriers when adopting recommendations to reduce childhood obesity. Economic considerations, especially time costs, may play a role in parental decisions to implement obesity-related recommendations and should be considered in the context of other priorities for the child and the family. Barriers should be routinely assessed and addressed when obesity-related recommendations are offered to enhance parental compliance. Future research should explore the extent to which identified barriers, including the needs and preferences of other family members, child preference, and economic considerations, influence parental decision making and should aim to identify approaches to surmounting these barriers.The authors declare that they have no competing interests.KS participated in the design and coordination of the study and helped to draft the manuscript. NL participated in the design of the study and conducted all qualitative analyses. ET and MG helped conceive of the study and participated in its design. LP conceived of the study, participated in its design, and helped to draft the manuscript. All authors read and approved the final manuscript.The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2431/9/81/prepub


Neutrophils generate potent microbicidal molecules via theoxygen-dependent pathway, leading to the generation of reactiveoxygen intermediates (ROI), and via the non-oxygen dependent pathway,consisting in the release of serine proteinases andmetalloproteinases stored in granules. Over the past years, theconcept has emerged that both ROI and proteinases can be viewed asmediators able to modulate neutrophil responses as well as the wholeinflammatory process. This is well illustrated by the oxidativeregulation of proteinase activity showing that oxidants andproteinases acts is concert to optimize the microbicidal activityand to damage host tissues. ROI and proteinases can modify theactivity of several proteins involved in the control of inflammatoryprocess. Among them, tumour necrosis factor-α andinterleukin-8, are elective targets for such a modulation. Moreover,ROI and proteinases are also able to modulate the adhesion processof neutrophils to endothelial cells, which is a critical step in theinflammatory process.


Ghana has an estimated one million orphans, 250,000 are due to AIDS parental deaths. This is the first study that examined the impact of parental HIV/AIDS status and death on the mental health of children in Ghana.In a cross-sectional survey, 4 groups of 200 children  aged between 10 and 19 were interviewed on their hyperactivity, emotional, conduct, and peer problems using the Strengths and Difficulties Questionnaire.Children whose parents died of AIDS showed very high levels of peer problems  whilst both orphaned groups scored similarly high on conduct problems . Hyperactivity showed no difference and was very low in the entire sample. Emotional problems were very high in all the groups except among the non-orphaned children .Orphans and children living with parents infected with HIV/AIDS are at heightened risks for emotional and behavioural disorders and that efforts to address problems in children affected by HIV/AIDS must focus on both groups of children. Parallel to this, researchers should see these findings as generated hypotheses (rather than conclusions) calling for further exploration of specific causal linkages between HIV/AIDS and children's mental health, using more rigorous research tools and designs. One of the biggest challenges of present health care efforts in Africa in the area of HIV/AIDS is how to provide care and support for the soaring numbers of orphaned children being created by the disease. Over 14 million of African children are orphaned by HIV/AIDS deaths and it is projected that 20 million children will be orphaned by 2010; at which time 12% of all children in sub-Sahara Africa will be orphaned to AIDS . There was also no significant difference between the ages of boys and girls . Using SPSS 15.0 a one Way MANOVA was conducted comparing the four groups  on their psychological outcomes with a .05 alpha level selected. In the analysis exposure of children to their parental AIDS status (groups) were entered as the independent variables and the psychological outcomes as dependent variables. Results indicated that parental HIV/AIDS status was significantly related to overall psychological outcome . A follow-up univariate analyses performed showed that HIV/AIDS exposure or status (group) was significantly associated with emotional problems , conduct problems  and peer problems  but not hyperactivity  and prosocial behaviours . These findings are presented in Table As predicted, post hoc contrasts using bonferroni test showed that non-orphaned children whose parents are not known to be infected with HIV/AIDS expressed significantly less emotional problems than children whose parents died of AIDS , children whose parents died of causes other than AIDS  and children whose parents are infected or living with HIV/AIDS . However, the differences showed between the latter 3 groups could not reach significance.Similarly, post hoc comparison indicated that children whose parents died of AIDS reported significantly higher conduct and anti-social problems than children whose parents are infected or living with HIV/AIDS  and non-orphaned children whose parents are not known to be infected with HIV/AIDS  but not children whose parents died of causes other than AIDS . Subsequently, children whose parents died of causes other than AIDS in turn were significantly higher on conduct problems than children whose parents are infected or living with HIV/AIDS  whilst the latter scored higher than non orphaned children .In addition, none of the paired multiple post hoc comparisons between groups of children whose parents died of causes other than AIDS, children living with parents infected with HIV/AIDS, and non-orphaned children whose parents are not known to be infected with HIV/AIDS on peer problems reached significance. However, children whose parents died of AIDS were significantly higher on peer problems than children whose parents died of causes other than AIDS , children whose parents are infected with HIV/AIDS  and non-orphaned children whose parents are not known to be infected with HIV/AIDS Finally, on total difficulties , it showed that children whose parents died of AIDS but not children whose parents died of causes other than AIDS and children whose parents are infected with HIV/AIDS, scored significantly higher than non-orphaned children whose parents are not known to be infected with HIV/AIDS.Table The current results extend the literature on the psychological health of children affected by HIV/AIDS by identifying some interesting findings among groups of children whose parents died of AIDS, children whose parents died of causes other than AIDS, children living with parents infected with HIV/AIDS, and non-orphaned children whose parents are not known to be infected with HIV/AIDS. Considering emotional problems, taken together, children living with parents infected with HIV/AIDS, and both children whose parents died of AIDS and children whose parents died of causes other than AIDS, showed similarly higher symptoms of depression and anxiety than non-orphaned children whose parents are not known to be infected with HIV/AIDS. Summarized differently, indications are that "orphanhood" and parental HIV/AIDS are associated with increased internalizing problems in children. Although this contrasts with other studies , the finThe study also found that children whose parents died of AIDS showed more peer problems than all other children. This supports previous and growing evidence which suggest that orphanhood by AIDS is significantly associated with increased peer relationship problems ,25,26. PThe self-reported levels of hyperactivity among the groups could not reach significance. This is consistent with earlier works that found that children orphaned by AIDS and non-orphaned children did not differ on hyperactivity . Other sThe relationship between parental death and HIV/AIDS illness on children's conduct problems was mixed, but similar to observations found on the emotional problems. Both orphaned groups scored significantly higher on conduct problems than children whose parents are infected with HIV/AIDS and non-orphaned children whose parents are not known to be infected with HIV/AIDS. However, children living with parents infected with HIV/AIDS expressed significantly higher conduct problems than non-orphaned children whose parents are not known to be infected with HIV/AIDS. Some researcher noted that the possibility of psychopathic behaviours due to children raised without supervision was the greatest fear that relates to the unknown psychosocial effects of orphanhood in Africa . But othThe general response rate of participants was very high. However, appropriate informants for orphaned children were not readily accessible. Furthermore, time constraints led to reliance on children's self - reports and no other informants recruited. The study recruited small samples of children and no data was collected on how long children were made orphaned. The present findings should also be understood in the context that several demographic characteristics such as the family socioeconomic background, place of residence and prior parent-child relationships were not controlled for. Finally, practitioners should be careful when drawing conclusions about clinical levels of distress reported as the SDQ cut-offs used in the present study have been determined on the basis of research with children in Western Europe and the USA, and that these norms have not been validated in Ghana. However, the strengths of the study include the fact that this is the first study to examine the psychological wellbeing of HIV/AIDS related vulnerable children in Ghana. A further main strength is that the study is the first in Africa and elsewhere that systematically compared groups of children whose parents died of AIDS, children whose parents died of causes other than AIDS, children whose parents are infected/living with HIV/AIDS, and non-orphaned children whose parents are not known to be infected with HIV/AIDS on their psychological outcomes in a single design. Finally, the study used a well established emotional and behavioural measure (Strength and Difficulties Questionnaire) with strong psychometric properties validated for several African countries .The main finding from the study is that orphaned children and children living with parents infected with HIV/AIDS are at heightened risk for psychological disorders, and in this study, exhibited signs of conduct, peer and emotional problems. The main implication is therefore the need to recognize the increased risk of emotional and behavioural disturbance in these children. Efforts by government agencies and NGO's working with HIV/AIDS affected children should focus on proposals to address these problems in both orphaned children and children living with parents infected with HIV/AIDS. Orphans and children living parents infected with HIV/AIDS are a growing population and so it is urgent that their short and long term psychological needs are cared for. Parallel to this and in the context of the limitations of the study, researchers must see the findings as generated hypotheses rather than conclusions. Further studies are needed to empirically examine larger populations to clarify the specifics of parental HIV/AIDS status or death on children's mental health. Such future studies must engage multiple informants including caregivers, parents, teachers and other immediate family relatives to generate data to be triangulated. It is well acknowledged that children report their own internal states with certainty but are frequently not reliable on their behaviours and by contrast, adults are reliable observers of children's behaviours but frequently underestimate children's internal distress. Future research should also compare orphaned children and foster children on their psychological wellbeing as fostering is not an uncommon practice in Africa.The author declares that they have no competing interests.The author designed the study, carried out the fieldwork and statistical analyses for an MPhil thesis under the supervision of Prof John-Arne Skolkekken. The author drafted this write up alone.


There have been many reports that high soya-based diets reduce the risk of certain types of cancer. This effect may be due to the presence of high levels of isoflavones derived from the soya bean, particularly genistein which has been shown to be a protein tyrosine kinase (PTK) inhibitor and have both oestrogenic and anti-oestrogenic properties. We have examined the effect of genistein and a number of novel synthetic analogues on both normal  and transformed  intestinal epithelial cell lines. Responses were compared to those elicited by oestradiol, the anti-oestrogen tamoxifen, and the tyrosine kinase inhibitor tyrphostin. Genistein and tamoxifen were potent inhibitors of cell proliferation. Of seven novel isoflavones tested, none were more potent inhibitors than genistein, and all displayed similar relative activities across the different cell lines. In addition to inhibiting cell proliferation, cell death via apoptosis was observed when the cells were exposed to the isoflavones and all but one exhibited PTK inhibitory activity. These data suggest that by reducing proliferation and inducing apoptosis, possibly due in part to PTK inhibition, isoflavones may have a role in protecting normal intestinal epithelium from tumour development (reducing the risk) and may reduce colonic tumour growth. © 1999 Cancer Research Campaign


Cognitive function declines with age throughout the animal kingdom and increasing evidence shows that disruption of the proteasome system contributes to this decline. The proteasome has important roles in multiple aspects of the nervous system, including synapse function and plasticity, as well as preventing cell death and senescence. We report that augmentation of proteasome function, using overexpression of the proteasome β5 subunit, enhances proteasome assembly and function. Significantly, we go on to show neuronal-specific proteasome augmentation slows age-related declines in measures of learning, memory, and circadian rhythmicity. Surprisingly neuronal specific proteasome augmentation of proteasome function also produces a robust increase of lifespan in Drosophila melanogaster. Our findings appear specific to the nervous system; ubiquitous proteasome overexpression increases oxidative stress resistance but does not impact lifespan and is detrimental to some healthspan measures. These findings demonstrate a key role of the proteasome system in brain aging.