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PubMed2002

Population-level effects of pesticides and other toxicants on arthropods.

New developments in ecotoxicology are changing the way pesticides and other toxicants are evaluated. An emphasis on life histories and population fitness through the use of demography, other measures of population growth rate, field studies, and modeling are being exploited to derive better estimates of pesticide impacts on both target and nontarget species than traditional lethal dose estimates. We review the state of the art in demographic toxicology, an approach to the evaluation of toxicity that uses life history parameters and other measures of population growth rate. A review of the literature revealed that 75 studies on the use of demography and similar measures of population growth rate in toxicology have been published since 1962. Of these 75 studies, the majority involved arthropods. Recent evaluations have indicated that ecotoxicological analysis based on population growth rate results in more accurate assessments of the impacts of pesticides and other toxicants because measures of population growth rate combine lethal and sublethal effects, which lethal dose/concentration estimates (LD/LC50) cannot do. We contend that to advance our knowledge of toxicant impacts on arthropods, the population growth rate approach should be widely adopted.

Animals↗
PubMed2026

Ancient DNA and Human Physiology.

Ancient DNA (aDNA) enables the reconstruction of chronologically sampled genomes from ancient humans, animals, plants, pathogens, and microorganisms, as well as environmental DNA, providing a record of biological changes through time. Improvements in short and degraded DNA extraction methods and low-cost sequencing now enable the generation of broad, cross-regional datasets that expand evolutionary analyses from past population demography to biological mechanisms. By tracking temporal shifts of allele frequencies, integrating functional genomics resources (e.g., gene expression, chromatin structure variation), modeling population demography to separate selection from genetic drift, and aligning genetic changes with archaeological, cultural, and climatic data, aDNA has the potential to link sequence variation to physiological function within their temporal and environmental contexts. In this review, we summarize illustrative case studies from aDNA research spanning complex traits, dietary adaptations, and responses to pathogens and other environmental changes, showing how human biology has evolved under multiple selective pressures through time. These dated signals help triage experimental work and expose mechanisms that are rare or absent in living cohorts. Although some challenges remain, such as geographic and temporal sampling disparities, limitations in data resolution and variant detection, and genotype-phenotype uncertainties, rapid methodological progress and stronger ethical frameworks are expanding what can be inferred, making aDNA a promising tool for refining physiological pathways, their timing, and their drivers.

Humans↗
PubMed2006

On the expected relationship between inbreeding, fitness, and extinction.

We assessed the expected relationship between the level and the cost of inbreeding, measured either in terms of fitness, inbreeding depression or probability of extinction. First, we show that the assumption of frequent, slightly deleterious mutations do agree with observations and experiments, on the contrary to the assumption of few, moderately deleterious mutations. For the same inbreeding coefficient, populations can greatly differ in fitness according to the following: (i) population size; larger populations show higher fitness (ii) the history of population size; in a population that recovers after a bottleneck, higher inbreeding can lead to higher fitness and (iii) population demography; population growth rate and carrying capacity determine the relationship between inbreeding and extinction. With regards to the relationship between inbreeding depression and inbreeding coefficient, the population size that minimizes inbreeding depression depends on the level of inbreeding: inbreeding depression can even decrease when population size increases. It is therefore clear that to infer the costs of inbreeding, one must know both the history of inbreeding (e.g. past bottlenecks) and population demography.

Adaptation, Physiological↗
PubMed2002

Developments in the instruction of biostatistics at the Kuwait University Health Science Centre in a decade.

BACKGROUND: Kuwait has witnessed many changes that influenced, among other things, the structure of medical education including biostatistics. This article describes the developments in biostatistics instruction and curriculum in the Health Science Centre, University of Kuwait, during the past 10 years. DESCRIPTION: Instead of teaching biostatistics as an independent component, the university has developed an integrated course (35 hr of lectures and 12 hr of tutorial sessions) of biostatistics, epidemiology, and demography that is taught to undergraduate medical and dentistry students to ensure interdisciplinary interaction, to remove redundancies, and to standardize terminology across the three disciplines. The core curriculum of the biostatistics course is compatible with the recommendations of the American Statistical Association. Separate biostatistics courses are also offered to pharmacy and allied health students to address their diverse interests. In addition, new biostatistics and computer applications instruction courses were developed and are taught to the students of the Master of Science (MSc), Master of Public Health (MPH), and PhD programs. For continuing medical education, a workshop on biostatistics and computer applications is organized annually for the medical profession as a collaboration between the Health Science Centre and the Kuwait Institute for Medical Specialization. EVALUATION: The instructor and curriculum content of the biostatistics courses are confidentially evaluated and independently analyzed by the office of the Vice Dean for Academic Affairs. Overall, students evaluate the biostatistics instructors highly and are pleased with the content of the biostatistics curriculum. CONCLUSIONS: During the last decade, biostatistics instruction in the Kuwait Health Science Centre had many new developments. An integrated course on biostatistics, epidemiology, and demography was developed with emphasis on problem solving and small group learning. Another biostatistics course is offered to the students of the new faculty of pharmacy. Further biostatistics courses became operational for the postgraduate programs: (MSc), (MPH), and PhD. Continuing medical education is supported by workshops, which is a sign of collaboration with the health community, and a consultancy office has been established. Overall, biostatistics instruction is well received by students, and the role of biostatistics is recognized by researchers from the medical profession.

Biometry↗
PubMed2000

Characteristics of children attending for dental general anaesthesia in 1993 and 1997.

OBJECTIVES: To confirm clinical observations and to investigate the characteristics (demography, dental anxiety status, dental health status, treatment experiences and dental health behaviours) of children attending for dental general anaesthesia (DGA). DESIGN: A case series design was used in which each consecutive parent and child, referred for DGA, were invited to take part. METHOD: Identical protocols for the selection of the sample, administration of the questionnaire and clinical examination were used to ensure comparability. To account for seasonal variation the data were collected during and between the months of January and May in both 1993 and 1997. Two hundred children and their parents were selected in 1993 and 200 in 1997. The parent completed a questionnaire. It enquired of the parent and child demography, parental dental anxiety status, and the child's treatment experiences. Children were asked to complete the Children's Fear Survey Schedule (CFSS) to assess their dental anxiety. The child's caries experience was assessed using the guidelines to standardise the collection of epidemiological data throughout the UK. RESULTS: Children studied in 1997 compared with 1993 were younger, had more decayed but fewer filled teeth, were more dentally anxious, more likely to present in pain and came from families who were in receipt of Government benefits. A linear regression analysis showed that the children with previous experience of DGA had higher levels of dental caries, fewer filled teeth, were older and attended in 1997. An individual regression for 1993 showed that an additional predictor was child attendance pattern. CONCLUSIONS: These findings confirmed the clinical observations and suggested that children who attend in pain and present for repeated DGA represent a group of children with special dental healthcare needs. There is a need for an integrated dental healthcare service to identify such children and provide appropriate dental care facilities for them.

Anesthesia, Dental↗
PubMed2006

Food and predators affect egg production in song sparrows.

Although the possibility that food and predators may interact in limiting avian populations has long been recognized, there have been few attempts to test this experimentally in the field. We conducted a manipulative food addition experiment on the demography of Song Sparrows (Melospiza melodia) across sites that varied in predator abundance, near Victoria, British Columbia, Canada, over three consecutive breeding seasons. We previously showed that food and predators had interactive effects on annual reproductive success (young fledged per female). Here, we report the effects on egg production. Our results show that food limits the total number of eggs laid over the breeding season ("total egg production") and that interactive food and predator effects, including food effects on nest predation, determine how those eggs are "parceled out" into different nests. Food addition alone significantly affected total egg production, and there was no significant interannual variability in this result. At the same time, both food and predators affected the two determinants of total egg production: "clutch number" (total number of clutches laid) and average clutch size. Both clutch number and size were affected by a food x predator x year interaction. Clutch number was lower at low-predator locations because there was less nest predation and thus less renesting. Food addition also significantly reduced nest predation, but there was significant interannual variation in this effect. This interannual variation was responsible for the food x predator x year interactions because the larger the effect of food on nest predation in a given year, the smaller was the effect of food on clutch number; and the smaller the effect of food on clutch number, the larger was the effect of food on clutch size. Potential predator and year effects on total egg production were thus cancelled out by an inverse relationship between clutch number and clutch size. We suggest that combined food and predator effects on demography could be the norm in both birds and mammals.

Animals↗
PubMed2006

Habitat-specific impacts of multiple consumers on plant population dynamics.

Multiple consumers often attack seeds, seedlings, and adult plants, but their population-level consequences remain uncertain. We examined how insect and small mammal consumers influenced the demography and abundance of the perennial shrub, bush lupine (Lupinus arboreus). In grassland and dune habitats we established replicate experimental lupine populations in 81-m2 plots that were either protected from, or exposed to, herbivorous voles and granivorous mice (via fencing) and/or root feeding insects (via insecticide treatment). Populations were initiated with transplanted seedlings in 1999 and 2000. We followed the demography of these cohorts, subsequent generations, and the seed bank for 5.5 years. Voles and insects killed many seedlings in dune (1999 only) and grassland (1999 and 2000) habitats. After 2000, insects and voles had minimal effects on seedling or adult survival. Seed predation by granivorous mice, however, greatly depressed seedling recruitment, resulting in lower adult lupine abundance in control plots vs. those protected from rodents. In grasslands, initial effects of voles and insects on seedling survival produced large differences among treatments in adult plant density and the cumulative number of seeds produced throughout the experiment. Differences among grassland populations in seed rain, however, had little influence on the magnitude of seedling recruitment into this habitat. Instead, recruitment out of a preexisting seed bank compensated for the lack of seed production in populations exposed to consumers. Shading by dense adults in plots protected from consumers limited seedling establishment within these populations. Although differences among populations in cumulative seed rain did not influence adult establishment, populations protected from consumers accumulated substantially larger seed banks than controls. These results illustrate how density dependence, habitat-specific seed dynamics, and particular demographic impacts of consumers interact to shape plant population responses to consumers.

Analysis of Variance↗
PubMed2005

[Risk factors for cystic fibrosis related liver disease]

OBJECTIVE: To identify the risk factors for cystic fibrosis related liver disease. METHODS: Ten patients out of a total of 106 patients regularly followed-up during 1999 met the clinical, biochemical and/or ultrasound criteria for liver disease (9.4%). Using information from the admissions records at the service, we collected data on demography, genotype, age and manifestations at diagnosis of cystic fibrosis, nutritional status and laboratory findings. Variables associated with liver disease were initially identified by the Kaplan-Meier method. Those factors that were significant in the univariate analysis were included in the multivariate analysis by means of a Cox regression model. RESULTS: Under univariate analysis the following factors were associated with liver disease: male sex, age at diagnosis of cystic fibrosis, pancreatic insufficiency, z score for weight at admission, Shwachman score and biochemistry at admission. After adjustment by Cox model, two variables were independently associated with liver disease: Shwachman score (p = 0.0057) and age at diagnosis of cystic fibrosis (p = 0.014). CONCLUSIONS: The risk of developing liver disease is higher among patients diagnosed at an early age and those with worse clinical status as assessed by the Shwachman score, indicating that liver involvement might be part of a more severe form of the condition. These patients merit greater attention in terms of screening for liver disease and should be given treatment with ursodeoxycholic acid earlier in the event of abnormal findings.

Journal Article↗
PubMed1999

Morbidity, deprivation, and antidepressant prescribing in general practice.

BACKGROUND: Although the link between depression, unemployment, and measures of deprivation and morbidity has been previously documented, the relationship between general practice prescribing of antidepressants, morbidity, and the social demography of general practice populations is poorly understood. AIM: To consider whether morbidity and the social demography of general practice populations influence the prescribing costs of individual practices. METHOD: Data were analysed, using a forward stepwise regression procedure, of all 78 practices served by the Cornwall and Isles of Scilly Health Authority. Data on prescribing for antidepressants were provided by the Prescription Pricing Authority for the period from July to December 1995 and converted into defined daily doses (DDDs) to standardize for the variation in prescribing practice between general practitioners. RESULTS: A significant positive correlation exists between the rates of prescribing DDDs of antidepressants by general practices and the prevalence of permanent sickness in the areas in which these practices serve. CONCLUSION: Demonstrating an association between morbidity and prescribing rates for depression may prove helpful in setting prescribing budgets.

Antidepressive Agents↗
PubMed2000

Problem drinking profiles of patients presenting to general practitioners: analysis of Alcohol Use Disorders Identification Test (AUDIT) scores for the Auckland area.

AIM: To quantify the prevalence and demography of at-risk and problematic drinkers in the population attending a random selection of general practices and to compare this with similar studies. METHOD: A study examining the uptake and utilisation of the "DRINKLESS" package to 369 New Zealand general practitioners was conducted during 1995/6. The "DRINKLESS" package was developed with the World Health Organisation collaborative study for brief intervention for at-risk alcohol consumption. The package uses the Alcohol Use Disorders Identification Test (AUDIT). There were 15,670 completed AUDIT questionnaires collected during the study. These were analysed to ascertain the prevalence and demography of at-risk and problematic drinkers attending general practitioners. RESULTS: There were 16% of patients identified as having either "risky drinking" or "problematic or dependent drinking". This pattern varied according to the occupation, age and gender of patients. CONCLUSIONS: The data confirm that large numbers of patients presenting to general practitioners experience alcohol problems of varying degrees. This study also suggests that the AUDIT will have satisfactory detection rates in a primary care setting.

Adolescent↗
PubMedDate not supplied

[Body mass, population density, and offspring number in mammals].

The negative relationship between population density and body mass with the body mass exponent of -0.75 implies that the energy flow through populations of small- and large-bodied species is the same, for individual metabolism scales to body mass raised to the power of +0.75. This relationship called the energetic equivalence rule, has often been observed for mammal species assemblages studied at regional scales. Here we suggest a demography-based mechanism that may generate it. Having analyzed about 130 literature sources, mostly in Russian, we collected demography and body-mass data for 88 mammalian species from the territory and coastal waters of the former Soviet Union. The data were used to construct a number of interspecific relationships. It is shown that (1) the number of offspring per lifetime is approximately inversely proportional to the relative mass at birth (the exponent is not significantly different from -1), (2) the average lifespan is proportional to body mass to the 0.25 power, (3) body mass at birth is proportional to the adult body mass. We develop a simple theory to demonstrate that relations (1) to (3) entail the energetic equivalence rule. The theory also allows us to explain violation of this rule (in non-flying birds, for example), namely, to predict the exponent of relation (1) for any given exponent of the relation between population density and body mass. This is possible because relations (2) and (3) are likely to more universally hold than relation (1). Finally, since natural selection acts on individual traits rather than on population-level ones such as population density, the theory opens up the way to an evolutionary explanation for the energetic equivalence rule.

Algorithms↗
PubMed2002

Intra-specific variations of two Leymus chinensis divergence populations in Songnen Plain, northeast China.

Population demography, seed production, biomass allocation, net photosynthesis and transpiration of two Leymus chinensis divergent populations and between two years in Songnen plain, northeast China were compared. Strong differences between the dry 1997 and moist 1998 occurred in vegetative shoot and sexual shoot densities, sexual differentiation and tiller densities, as well as in the lengths of inflorescence, seed numbers per inflorescence, seed weights and biomass allocation in each population respectively (P < 0.01). While strong differences between the two populations occurred in vegetative shoot densities, sexual shoot densities, sexual differentiation and seed weights in each year (P < 0.01). The differences between the two populations in tiller densities and in biomass allocation to sexual shoots were significant (P < 0.05). But there were no significant differences between the two populations in the lengths of inflorescence, seed numbers per inflorescence and biomass allocation to rhizomes and vegetative shoots (P > 0.05). Excepting the transpiration rate in the early June, the differences between the two populations in net photosynthesis and transpiration rate of vegetative shoots and sexual shoots were strongly significant in the early June and July respectively (P < 0.01). Relative stable variations in population demography and physiological traits between the two populations indicated that they are divergently in the Songnen Plain.

Adaptation, Physiological↗
PubMedDate not supplied

[The vital potential of population during the market-reform period].

Estimates of the vital potential of population in the Astrakhan Region during the 1990-2000 market reforms, which were obtained on the basis of the continuous statistic observations of the total number of births and deaths during the mentioned period as well as on the basis of demography tables and potential demography, are described in the paper. An evaluation of man's "weight", expressed in man-years, is defined with respect to age and sex. The below phenomena are typical of the reform time: prevalence of the share of female vital potential; functionality of the life potential of citizens aged 0 to 19 and 20 to 59; a decreased role of the life potential of citizens aged 0 to 19 due to a low fertility; a diminished share of the life potential among able-bodied men; a decreased correlation index of the life potential of men versus women; a growing life potential in children aged above 1 year due to the paradox of the mean life expectancy; an increasing life potential within the age range of 10 years due to a dropped birth rate in the 90-ies and to the aging process because of the low birth rate and, correspondingly, low children's mortality rate; and compensation of losses in the life potential of men and women primarily due to the aging process.

Adolescent↗
PubMedDate not supplied

[Long-term dynamic of fecal corticosterone and its ecological and social correlates in males of great gerbil (Rhombomys opimus Licht.). Non-invasive approach in studies of stress in natural populations].

The relationship between fecal corticosterone concentrations and characteristics of the environment and population demography were studied in adult male gerbils (Rhombomys opimus Licht.) at the southern border of Kyzylkum desert (Reserve "Ecocentre Dzeiran", Bukhara region, Republic Uzbekistan) in spring and fall seasons from 1999 to 2004. We extracted hormones from air-dried fecal samples and analyzed their concentrations by radioimmunoassay (Gerlinskaya et al., 1993). An analysis for year-specific relationships between hormone concentrations and environmental variables of temperature and precipitation using Pearson's r statistic revealed that corticosterone concentrations correlated positively with total precipitation in January and February and negatively with precipitation during March and April. There was also a significant negative relationship between fecal corticosterone and the number of hot days in March (>20 degrees C). Demographic variables that characterized population densities (percent of burrow systems occupied, mean and maximum number of burrow systems/1 ha, number of females in the burrow system) correlated positively with corticosterone concentrations in feces in the beginning of spring, but these relationships were small compared with mean concentrations of corticosterone for the entire spring season that were strongly and positively correlated with number of gerbils, including all pups emerged, in burrow systems owned by one male (within its home range). In contrast, correlation coefficients of corticosterone concentrations with characteristics of feeding resources in the spring were low and negative. In the long-term perspective (interannual comparison), mortality among adult males was highly negatively correlated with mean corticosterone concentrations in the beginning of spring, which is within the period of maximum reproductive effort and potential stress. Body mass was independent of corticosterone concentrations in males in either the beginning of spring, or during the whole spring. In the fall, mean concentrations of fecal corticosterone in males was positively correlated with the number of days from June to October with mean daily temperatures exceeding 30 degrees C, and with percent of burrow systems where at least one adult, > or = 1 year old gerbil had survived. Mortality from fall to spring of the next year and the fall body mass did not correlate with concentrations of corticosterone in feces collected in the fall. When we analyzed corticosterone concentrations in spring seasons of all years combined using a stepwise regression analysis of a sampling of individual males (we analyzed residuals after withdrawal of year effect) on a set of variables representing habitat resources, distances between nearest neighbor males, and variables representing group demography we found low R2 values not exceeding 0.17. Within the six-year period, concentrations of corticosterone in the spring related negatively with abundance of annual herbs and positively with number of females in a male's social group. When only years of high density were analyzed, fecal corticosterone concentrations in males in the spring were again negatively determined by abundance of herbs, as well as by the nearest neighbor distance, and positively determined by the number of females within a male's home range. At the beginning of spring the only determinants were distance to the nearest neighbor male and number of females. In years of low density none of the variables were found to affect corticosterone levels during the whole spring, while in the beginning of spring only partial regression coefficients of abundance of herbs were negative and significant. Stepwise logistic regression analysis revealed positive dependence (P = 0.05) of disappearance of adult males during summer drought on concentrations of fecal corticosterone in the spring, but only when burrow systems with at least one adult (male or female) surviving after the summer were considered. Our results provide evidence ground for the assumption that in a desert rodent with non-regular population fluctuations such as the great gerbil, density may be more suppressed by external factors and not by density dependent mortality mediated by stress. Density dependent increases of stress caused by intense reproductive effort occurred when feeding and climatic conditions were favorable to compensate for negative effects on survival. However, in individual gerbils mortality mediated by stress can take place because we found higher stress in the beginning of spring in males, which did not occur in the population after the summer drought.

Animals↗
PubMed2005

Effect of an education program on the prevention of ventilator-associated pneumonia: A multicenter study.

OBJECTIVE: To evaluate the effect of an educational program targeted on modifiable risk factors on ventilator-associated pneumonia (VAP) rates. MATERIAL AND METHOD: After a preliminary study on VAP risk factors was conducted at one teaching hospital, a pre- and post-interventional study was then performed on 12 hospitals in Thailand from January 1, 2002 to June 30, 2003. Each hospital randomly selected 20 patients, who were on mechanical ventilation to be enrolled The study was divided into two phases; 1) pre-intervention, 2) post-intervention. Data collected included patients 'demography and risk factors for VAP During pre-interventional phase, data on risk factors for VAP was analyzed and fedback to healthcare providers in the wards by an infection control nurse (ICN) of the individual hospital. An educational programme on the prevention of VAP was introduced by the ICN. Ventilator-associated pneumonia rates and their risk factors were continuously monitored during the post-interventionl phase. RESULTS: Two hundred and forty four patients in the pre-interventional phase and 254 patients in the post-interventional phase were included. There was no significant difference in the demography between these two patient populations. After the intervetion, there was a significant improvement in hand-hygiene practices (p<0.001) among healthcare providers and increased use of sucralfate (p=0.05) for stress ulcer prophylaxis. Ventilation-associated pneumonia rate (40.5% vs. 24%; p<0.001) and crude mortality rate associated with VAP (12.3% vs. 8.7%; p<0.001) were also reduced CONCLUSION: The educational programme targeted on modifiable risk factors for prevention of VAP was effective and should be considered as an intervention to reduce VAP rates in developing countries.

Cross Infection↗
PubMed1997

[Prognosis one year after hip fracture].

This study evaluates the demography and health in a hip fracture population, and predictors of outcome one year after the fractures occurred. Physical, mental and social functioning in 109 patients who were referred from home with hip fractures were assessed retrospectively; during the hospital stay, at discharge, and after 4 and 12 months. Mobility, Katz' ADL-index and a short-version of MMSE were used in assessing their physical and mental conditions. No essential changes were found in either demography or health. The most significant predictors of outcome were age, prefracture mobility and post-fracture mental status. The proportion of patients suffering from acute confusion was considerable. The result was a higher risk of mortality, institutionalisation and poor physical outcome. It is important to pay more attention to the prevention and treatment of cases involving acute confusion.

Activities of Daily Living↗
PubMed1998

[Psychological malaise and the sociodemographic and familial characteristics of the over-user of primary care].

OBJECTIVES: To find the social, demographic and family characteristics, the psychological malaise and reasons for consultation of normal and hyper-attenders at a primary care practice. DESIGN: Crossover study with a control. SETTING: Primary care. PATIENTS: 127 hyper-attenders (they attended the practice as often as, or more often than, the mean number of visits, stratified by sex and age) and 120 normal attenders chosen by stratified random sampling. INTERVENTIONS: Questionnaire with characterisation data, family demography, psychological malaise (Goldberg general health questionnaire) and reasons for consultation. RESULTS: To be considered a hyper-attender, the number of attendances per year ranged from > or = 8 (in 15 to 44-year olds) to > or = 20 (in men over 65). Hyper-attenders were about 12% of almost all groups, except in men between 45 and 64 and women over 64, in whom it was around 18%. We found no relevant differences between normal and hyper-attenders as to demography or perception of family function. In almost 60% of hyper-attenders and 34% of normal attenders (p < 0.001), psychological malaise was detected. CONCLUSIONS: If the definition of hyper-attenders is stratified by age and sex, their social and demographic characteristics are very different from in other studies, even though there are a similar number of them. However, these demographic and/or family characteristics are similar in normal and hyper-attenders.

Adolescent↗
PubMed1996

Population geography of calamity: the sixteenth and seventeenth century Yucatan.

"This historical demography for Yucatan [Mexico] at the time of Spanish contact presents a number of problems. There were multiple Maya-Spaniard contacts before the Spaniards established a continuous presence after the protracted conquest of the Yucatan. The area of Yucatan that was controlled by the Spanish at any one time is not precisely known, and Yucatan offered ¿refuge' areas where the indigenous population could avoid Spanish control and counts. These issues are addressed here by considering different regions of the Yucatan and using a numerical computer simulation to generate new estimates of population that result from migration, warfare, agricultural calamity, and epidemics."

Americas↗