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PubMed1999

Do memory complaints indicate the presence of cognitive impairment? Results of a field study.

BACKGROUND: In the context of suspected cognitive disorders, the validity of memory complaints is subject to considerable debate. This investigation documents the prevalence of memory complaints and assesses the validity of memory complaints for detecting cognitive impairment. METHODS: The sample comprises 349 randomly selected non-institutionalized individuals, aged 75 and over living in the city of Leipzig. Twenty individuals who suffer from moderate and severe dementia according to DSM-III-R were excluded. Memory complaints were measured by means of a single item question. The Mini-Mental State Examination (MMSE) and a wider range of cognitive tests which constitute the short neuropsychological battery of the SIDAM (Structured Interview for the Diagnosis of dementia of Alzheimer type, Multi-infarct dementia and dementias of other etiology according to ICD-10 and DSM-III-R) were used to test cognitive performance. RESULTS: One in three individuals aged 75 and over complained about memory deficits. The MMSE is not significantly related to memory complaints, whereas poorer performance on 2 out of 8 tests regarding specific areas of cognitive function (immediate recall, short-term memory) were found to be significantly associated with memory complaints. Despite these statistically significant associations, it is shown that memory complaints do not have diagnostic validity in detecting cognitive impairment on the individual level. CONCLUSION: Memory self-assessment should not be used as a substitute measure of cognitive performance. Initiation of further diagnostic and therapeutic steps should be based on cognitive performance testing. Relaying solely on memory complaints would miss individuals in need and allocate resources to worried but cognitively healthy persons.

Aged↗

PubMed2004

Ecotypic differentiation and phenotypic plasticity in reproductive traits of Armadillidium vulgare (Isopoda: Oniscidea).

Armadillidium vulgare differed in growth and survivorship on two field sites. Growth rates were higher at a site with consistently higher quality food than at the other site where less high-quality food was produced and which was less predictably accessible. Survivorship was higher at the second site where temperature fluctuations were consistently smaller. Individuals from the two populations were kept for 6 months under the same food and temperature conditions and patterns of resource allocation to reproductive traits analysed. Members of the population from the site with good growth conditions had significantly higher reproductive allocation, by 13.5%, and larger broods, by 9.1%, than those from the site with poor growth conditions. Contrary to theoretical predictions, they also had significantly larger offspring, by 7.5% dry mass. Larger offspring survived better than small ones. This differential survivorship, by 20% for a 3.4% difference in live mass, was much more pronounced under conditions of moisture stress and under fluctuating temperature regimes. Larger offspring would therefore be at a selective advantage on the site with more severe temperature fluctuations. Phenotypic plasticity in reproductive traits in response to experimental changes in food quality, temperature and crowding were monitored. Reproductive allocation was increased by 20.8% under conditions of higher food quality, by 14.7% at higher temperatures, and by 12.5% under less crowded conditions. Brood size, but not offspring dry mass, increased when food quality increased. When crowding increased by 25.0%, the size of broods remained the same but the dry mass of individual offspring decreased by 11.2%. Members of the population from the site with more variable access to high-quality food showed more plasticity in reproductive traits in response to changes in food supply than members of the population from the site with the more predictable food supply. Members of the population from the site with more stable temperatures showed less plasticity to temperature changes than members of the population from the site with greater temperature fluctuations. It is concluded that the observed microevolutionary processes and phenotypic plasticity have adaptative value as responses to spatial and temporal heterogeneity in environmental conditions.

Adaptation, Physiological↗

PubMed2005

Examining the strength and possible causes of the relationship between fire history and Sudden Oak Death.

Fire can be a dominant process in the ecology of forest vegetation and can also affect forest disease dynamics. Little is known about the relationship between fire and an emerging disease epidemic called Sudden Oak Death, which is caused by a new pathogen, Phytophthora ramorum. This disease has spread across a large, fire-prone portion of California, killing great numbers of oaks and tanoaks and infecting most associated woody plants. Suitable hosts cover a much broader geographic range, raising concern over where the disease may spread. To understand the strength and potential sensitivities of a fire-disease relationship, we examined geographic patterns of confirmed P. ramorum infections in relation to past fire history. We found these infections to be extremely rare within the perimeter of any area burned since 1950. This finding is not caused by spatial bias in sampling for the disease, and is robust to variation in host abundance scenarios and to aggregation of closely spaced sampling locations. We therefore investigated known fire-related factors that could result in significantly lower incidence of the disease in relatively recently burned landscapes. Chemical trends in post-fire environments can influence the success of pathogens like P. ramorum, either by increasing plant nutrient stress or by reducing the occurrence of chemicals antagonistic to Phytophthoras. Succession in the absence of fire leads to greater abundance of host species, which will provide increased habitat for P. ramorum; this will also increase intraspecific competition where these trees are abundant, and other density-dependent effects (e.g. shading) can reduce resource allocation to defenses. Despite these findings about a fire-disease relationship, a much deeper understanding is necessary before fire can be actively used as a tool in slowing the epidemic.

California↗

PubMed2005

Contribution analysis of body mass dynamics in Daphnia.

The concept of body mass dynamics can be viewed as part of life history theory, but its potential has remained largely untapped due to a lack of analytical methodology. We therefore propose a method, called contribution analysis, which enables us to decompose a change in body mass into contributions associated with variations in individual egg mass, clutch size, and standard somatic mass (somatic mass adjusted to body length). The advantage of contribution analysis is that various contributions are expressed in the same units (units of mass) and show the amount of resources committed to changes in the individual traits, while the traits themselves are measured in different units and thus incomparable on their own. The method is tuned to study zooplankton, and is applied to examine body mass dynamics in Daphnia galeata. We found that when recovering from a poor-resource environment just above the threshold food concentration, Daphnia primarily increase their standard somatic mass, that is, restore body condition. When the trophic environment improves further but remains below the incipient limiting level, resources are invested equally to enhance body condition and reproduction in terms of clutch size. Finally, when food is no longer a limiting factor, almost all resources are committed to increase clutch size. While individual egg mass also varies, it never attracts more resources than the shift in the most prioritized trait. We suggest that the significance of this shift in resource allocation priorities is to keep an adult female alive in a poor environment and thus to allow her to retain her reproductive potential for better conditions in the future. Contribution analysis of body mass dynamics may allow us to detect flexible allocation strategies in a changing natural environment.

Animals↗

PubMed2006

Correlation of metabolism with tissue carbon and nitrogen turnover rate in small mammals.

Stable isotopes have proven to be a useful tool for deciphering food webs, examining migration patterns and determining nutrient resource allocation. In order to increase the descriptive power of isotopes, an increasing number of studies are using them to model tissue turnover. However, these studies have, mostly by necessity, been largely limited to laboratory experiments and the demand for an easier method of estimating tissue turnover in the field for a large variety of organisms remains. In this study, we have determined the turnover rate of blood in mice and rats using stable isotope analysis, and compared these rates to the metabolic rates of the animals. Rats (Rattus norvegicus) (n=4) and mice (Mus musculus) (n=4) were switched between isotopically distinct diets, and the rate of change of delta(13)C and delta(15)N in whole blood was determined. Basal metabolic rates (as CO(2) output and O(2) consumption per unit time, normalized for mass) were determined for the rats and mice. Rats, which were an order of magnitude larger and had a slower metabolic rate per unit mass than mice (0.02 vs. 0.14 O(2)/min/g), had a slower blood turnover than mice for (13)C (t (1/2 )=24.8 and 17.3 days, respectively) and (15)N (t (1/2 )=27.7 and 15.4 days, respectively). A positive correlation between metabolic rate and blood isotopic turnover rate was found. These are the only such data for mammals available, but the literature for birds shows that mass and whole-body metabolic rates in birds scale logarithmically with tissue turnover. Interestingly, the mammalian data graph separately from the bird data on a turnover versus metabolic rate plot. Both mice and rat tissue in this study exhibited a slower turnover rate compared to metabolic rate than for birds. These data suggest that metabolic rate may be used to estimate tissue turnover rate when working with organisms in the field, but that a different relationship between tissue turnover and metabolism may exist for different classes of organisms.

Animals↗

PubMed2006

Ecological role of reindeer summer browsing in the mountain birch (Betula pubescens ssp. czerepanovii) forests: effects on plant defense, litter decomposition, and soil nutrient cycling.

Mammalian herbivores commonly alter the concentrations of secondary compounds in plants and, by this mechanism, have indirect effects on litter decomposition and soil carbon and nutrient cycling. In northernmost Fennoscandia, the subarctic mountain birch (Betula pubescens ssp. czerepanovii) forests are important pasture for the semidomestic reindeer (Rangifer tarandus). In the summer ranges, mountain birches are intensively browsed, whereas in the winter ranges, reindeer feed on ground lichens, and the mountain birches remain intact. We analyzed the effect of summer browsing on the concentrations of secondary substances, litter decomposition, and soil nutrient pools in areas that had been separated as summer or winter ranges for at least 20 years, and we predicted that summer browsing may reduce levels of secondary compounds in the mountain birch and, by this mechanism, have an indirect effect on the decomposition of mountain birch leaf litter and soil nutrient cycling. The effect of browsing on the concentration of secondary substances in the mountain birch leaves varied between different years and management districts, but in some cases, the concentration of condensed tannins was lower in the summer than in the winter ranges. In a reciprocal litter decomposition trial, both litter origin and emplacement significantly affected the litter decomposition rate. Decomposition rates were faster for the litter originating from and placed into the summer range. Soil inorganic nitrogen (N) concentrations were higher in the summer than in the winter ranges, which indicates that reindeer summer browsing may enhance the soil nutrient cycling. There was a tight inverse relationship between soil N and foliar tannin concentrations in the winter range but not in the summer range. This suggests that in these strongly nutrient-limited ecosystems, soil N availability regulates the patterns of resource allocation to condensed tannins in the absence but not in the presence of browsing.

Analysis of Variance↗

PubMed2004

Masting by Betula-species; applying the resource budget model to north European data sets.

Masting, the intermittent production of large crops of flowers by a plant population, is a common feature among trees in boreal and temperate forests. The pollen of many broadleaved trees causes allergic diseases, which are major causes of increasing health-care costs in industrialised countries. As the prevalence and severity of allergic diseases are connected with the concentrations of airborne pollen, an universal model predicting the intensity of the coming flowering would be a valuable tool for pollen information services, and ultimately for allergic people and allergologists. We investigated whether a resource budget model created in Japan explains the fluctuations in the annual pollen sums of Betula-species in north European data sets (10-12 years at 4 sites, 20 years at 10 sites). Using the shorter data sets, the model explained 76-92% of the annual fluctuations at five study sites. Using the 20-year data set, the percentage for southern Finland was much lower, only 48%, compared with the 85% of the 12-year data set. The annual pollen sums have been higher during the 1990s than in the 1980s, which may explain the ineffectiveness of the model, while applied to the 20-year data set. Our results support the resource budget model: the masting of birch species is regulated by weather factors together with the system of resource allocation among years. The model can serve pollen information service. However, only the 10 most recent years should be used to avoid interference from trends in changing vegetation and/or climate.

Betula↗

PubMed2005

Frequency of emergency room visits for childhood asthma in Ottawa, Canada: the role of weather.

The aim of this study was to evaluate associations between meteorological conditions and the number of emergency department visits for asthma in a children's hospital in Ottawa, Canada. A case-crossover study design was used. Hospital emergency department visits for asthma between 1992 and 2000 were identified based on patients' presenting complaints. We obtained hourly measures for the following meteorological variables: wind speed, temperature, atmospheric pressure, relative humidity, and visibility. Particular emphasis was placed on exploring the association between asthma visits and fog, thunderstorms, snow, and liquid and freezing forms of precipitation. In total, there were 18,970 asthma visits among children between 2 and 15 years of age. The number of visits and weather characteristics were grouped into 6 h case and control intervals. The occurrence of fog or liquid precipitation was associated with an increased number of asthma visits, while snow was associated with a reduced number (P<0.05). Stratified analyses by season found no association in any of the four calendar intervals between the number of asthma visits and visibility, change in relative humidity and change in temperature. In contrast, summertime thunderstorm activity was associated with an odds ratio of 1.35 (95% CI=1.02-1.77) relative to summer periods with no activity. Models that incorporate calendar and meteorological data may help emergency departments to more efficiently allocate resources needed to treat children presenting with respiratory distress.

Adolescent↗

PubMed2004

Attentional enhancement to NoGo stimuli in anxious children.

OBJECTIVE: To measure neurophysiological correlates of inhibition in children with anxiety disorders. METHOD: Anxiety-disordered children and healthy control children (11 years of age) performed a cued Continuous Performance Test (CPT-AX). Event-related potentials following NoGo and distractor stimuli as well as performance data were examined for group differences. RESULTS: Anxious children displayed a significantly larger NoGo-related N1 global field power than did control children while no group differences were found for the N2 and P3 potentials. Groups did not differ in CPT performance. CONCLUSIONS: Anxious children showed early attentional enhancement (N1) to stimuli indicating need for inhibition but not increased resource allocation to actual response inhibition.

Analysis of Variance↗

PubMed2006

Misclassification of race/ethnicity in a population-based cancer registry (United States).

Cancer registry data on race/ethnicity are vital for understanding cancer patterns in population subgroups, as they inform public health policies for allocating resources and form the bases of etiologic hypotheses. However, accuracy of cancer registry data on race/ethnicity has not been systematically evaluated. By comparing race/ethnicity in the Greater Bay Area Cancer Registry to self-reported race/ethnicity for patients from 14 racial/ethnic groups, we determined the accuracy of this variable and the patient and hospital characteristics associated with disagreement. The extent of misclassification (measured by sensitivity and predictive value positive (PV+)) varied across racial/ethnic groups (total n=11,676). Sensitivities and PV+'s were high (exceeding 90%) for non-Hispanic Whites and Blacks, moderate for Hispanics and some Asian subgroups (70-90%), and very low for American Indians (<20%). Overall, registry and interview race/ethnicity disagreed for 11% of the sample. In a multivariate model, disagreement was associated with non-White race/ethnicity, younger age, being married, being foreign-born but preferring to speak English, and diagnosis in a large hospital. Improving data quality for race/ethnicity will be most effectively attempted at the reporting source. We advocate a concerted effort to systematize collection of these patient data across all facilities, which may be more feasible given electronic medical admissions forms.

Bias↗

PubMed2005

Clarifying efficiency-equity tradeoffs through explicit criteria, with a focus on developing countries.

Expenditures on health in many developing countries are being disproportionately spent on health services that have a low overall health impact, and that disproportionately benefit the rich. Without explicit consideration of priority setting, this situation is likely to remain unchanged: resource allocation is too often dictated by historical patterns, and maintains vested interests. This paper explores how prioritization between different health interventions can be rationalised by the use of clearly defined criteria. A number of key efficiency and equity criteria are examined, in particular analysing how potential tradeoffs could be incorporated into the decision making process.

Cost-Benefit Analysis↗

PubMed2006

Cost accounting to determine prices: how well do prices reflect costs in the German DRG-system?

Germany has recently introduced a system of Diagnosis Related Groups (DRGs) to engender more appropriate resource allocation. The following article describes the German DRG-system and the methodologies used to determine prices. It analyses the extent to which prices, or calculated cost weights, reflect the actual costs incurred by hospitals for their respective services. We reveal that a "compression" of DRG cost weights occurs, and that the data sample used to calculate cost weights is lacking in terms of its representativeness. Although cost data accuracy has improved over the last few years there are still a number of challenges that need to be addressed.

Accounting↗

PubMed2005

GNARE: automated system for high-throughput genome analysis with grid computational backend.

Recent progress in genomics and experimental biology has brought exponential growth of the biological information available for computational analysis in public genomics databases. However, applying the potentially enormous scientific value of this information to the understanding of biological systems requires computing and data storage technology of an unprecedented scale. The Grid, with its aggregated and distributed computational and storage infrastructure, offers an ideal platform for high-throughput bioinformatics analysis. To leverage this we have developed the Genome Analysis Research Environment (GNARE)--a scalable computational system for the high-throughput analysis of genomes, which provides an integrated database and computational backend for data-driven bioinformatics applications. GNARE efficiently automates the major steps of genome analysis including acquisition of data from multiple genomic databases; data analysis by a diverse set of bioinformatics tools; and storage of results and annotations. High-throughput computations in GNARE are performed using distributed heterogeneous Grid computing resources such as Grid2003, TeraGrid, and the DOE Science Grid. Multi-step genome analysis workflows involving massive data processing, the use of application-specific tools and algorithms and updating of an integrated database to provide interactive web access to results are all expressed and controlled by a "virtual data" model which transparently maps computational workflows to distributed Grid resources. This paper describes how Grid technologies such as Globus, Condor, and the Gryphyn Virtual Data System were applied in the development of GNARE. It focuses on our approach to Grid resource allocation and to the use of GNARE as a computational framework for the development of bioinformatics applications.

Computational Biology↗

PubMed2005

Cost-effectiveness of a community-level HIV risk reduction intervention for women living in low-income housing developments.

We conducted a cost-effectiveness analysis of a multi-site community-level HIV prevention trial that enrolled women living in 18 low-income housing developments in 5 U.S. cities. A mathematical model of HIV transmission was used to estimate the number of HIV infections averted and quality-adjusted life years (QALYs) saved by the community-level intervention, based on data obtained from community-wide sexual behavior surveys at baseline and 12-month follow-up. Results indicated that the intervention prevented approximately 1 infection per 3500 women reached by the intervention, at a total cost of 174,845 dollars. The cost per QALY saved by the intervention was 37,433 dollars and the cost per HIV infection averted was 732,072 dollars. The community-level intervention was moderately cost-effective in comparison with other HIV prevention programs for at-risk women. Synergistic approaches to HIV prevention that combine community-level sexual norm change interventions with more intensive risk reduction programs for high-risk women are needed. EDITORS' STRATEGIC IMPLICATIONS: The authors present a promising and efficient community-level HIV prevention approach, with effects beyond the limited scope of individual or small group interventions. This paper represents an example of how an analysis of cost-effectiveness can provide policymakers with information needed for difficult decisions about prevention resource allocations.

Adult↗

PubMed2005

Sulfur and primary production in aquatic environments: an ecological perspective.

Sulfur is one of the critical elements in living matter, as it participates in several structural, metabolic and catalytic activities. Photosynthesis is an important process that entails the use of sulfur during both the light and carbon reactions. Nearly half of global photosynthetic carbon fixation is carried out by phytoplankton in the aquatic environment. Aquatic environments are very different from one another with respect to sulfur content: while in the oceans sulfate concentration is constantly high, freshwaters are characterized by daily and seasonal variations and by a wide range of sulfur concentration. The strategies that algal cells adopt for energy and resource allocation often reflect these differences. In the oceans, the amount and chemical form of sulfur has changed substantially during the course of the Earth's history; it is possible that sulfur availability played a role in the evolution of marine phytoplankton communities and it may continue to have appreciable effects on global biogeochemistry and ecology. Phytoplankton is also the main biogenic source of sulfur; sulfur can be released into the atmosphere by algal cells as dimethylsulfide, with possibly important repercussions on global climate. These and related matters are discussed in this review.

Animals↗

PubMed2006

Bridge-it: a system for predicting implementation fidelity for school-based tobacco prevention programs.

Properly implemented school programs to prevent tobacco use and addiction can lower smoking prevalence up to 60%. However, numerous programs are not successful due to poor implementation. A system for estimating likelihood of future implementation fidelity of school-based prevention programs was tested using data collected at baseline and two year follow-up in 47 middle schools and high schools participating in the Texas Tobacco Prevention Initiative. The Bridge-It system includes an eight-factor, 36-item survey to analyze capacity for program implementation and a companion Bayesian model which provides estimations of likelihood of implementation fidelity several years after program initiation. The survey also asks about amount of implementing activity for each of the multiple components recommended in federal guidelines for school programs to prevent tobacco use. Criterion referenced cross-tabulations showed the system's forecast of implementation fidelity was correct in 74% of cases (p < .01). Model reliability was confirmed in regression analyses. Implementation fidelity at follow-up was predicted by the combination of the model's eight capacity factors at baseline. It includes program, implementation support, and non-program factors. Integration of the Bridge-It system, or comparable tools, into the dissemination and evaluation of school-based prevention programs can help to increase understanding of factors that influence implementation and provide guidance for capacity building. If administrators can identify at baseline schools likely to fall short of implementation goals, plans for resource allocation and provision of guidance, training, and technical assistance can be specifically tailored to identified needs.

Humans↗

PubMed2006

The PedsQL 4.0 as a school population health measure: feasibility, reliability, and validity.

BACKGROUND: The application of health-related quality of life (HRQOL) as a school population health measure may facilitate risk assessment and resource allocation, the tracking of student health at the school and district level, the identification of health disparities among schoolchildren, and the determination of health outcomes from interventions and policy decisions at the school, district, and county level. OBJECTIVE: To determine the feasibility, reliability, and validity of the 23-item PedsQL 4.0 (Pediatric Quality of Life Inventory) Generic Core Scales as a school population health measure for children and adolescents. DESIGN: Survey conducted in 304 classes at 18 elementary schools, 4 middle schools, and 3 high schools within a large metropolitan school district. METHODS: The PedsQL 4.0 Generic Core Scales (Physical, Emotional, Social, School Functioning) were completed by 2437 children ages 8-18 and 4227 parents of children ages 5-18. RESULTS: The PedsQL 4.0 evidenced minimal missing responses, achieved excellent reliability for the Total Scale Score (alpha = 0.89 child, 0.92, parent report), and distinguished between healthy children and children with chronic health conditions. The PedsQL 4.0 was related to indicators of socioeconomic status (SES) at the school and district level. The PedsQL School Functioning Scale was significantly correlated with standardized achievement scores based on the Stanford 9. CONCLUSION: The results demonstrate the feasibility, reliability and validity of the PedsQL 4.0 Generic Core Scales as a school population health measure. The implications of measuring HRQOL in schoolchildren at the school, district, and county level for identifying and ameliorating health disparities are discussed.

Adolescent↗

PubMed2005

Evaluating the induced-odour emission of a Bt maize and its attractiveness to parasitic wasps.

The current discussion on the safety of transgenic crops includes their effects on beneficial insects, such as parasitoids and predators of pest insects. One important plant trait to consider in this context is the emission of volatiles in response to herbivory. Natural enemies use the odours that result from these emissions as cues to locate their herbivorous prey and any significant change in these plant-provided signals may disrupt their search efficiency. There is a need for practical and reliable methods to evaluate transgenic crops for this and other important plant traits. Moreover, it is imperative that such evaluations are done in the context of variability for these traits among conventional genotypes of a crop. For maize and the induction of volatile emissions by caterpillar feeding this variability is known and realistic comparisons can therefore be made. Here we used a six-arm olfactometer that permits the simultaneous collection of volatiles emitted by multiple plants and testing of their attractiveness to insects. With this apparatus we measured the induced odour emissions of Bt maize (Bt11, N4640Bt) and its near-isogenic line (N4640) and the attractiveness of these odours to Cotesia marginiventris and Microplitis rufiventris, two important larval parasitoids of common lepidopteran pests. Both parasitoid species were strongly attracted to induced maize odour and neither wasp distinguished between the odours of the transgenic and the isogenic line. Also wasps that had previously experienced one of the odours during a successful oviposition divided their choices equally between the two odours. However, chemical analyses of collected odours revealed significant quantitative differences. The same 11 compounds dominated the blends of both genotypes, but the isogenic line released a larger amount of most of these. These differences may be due to altered resource allocation in the transgenic line, but it had no measurable effect on the wasps' behaviour. All compounds identified here had been previously reported for maize and the differential quantities in which they were released fall well within the range of variability observed for other maize genotypes.

Animals↗