Population characteristics of domestic Aedes aegypti (Diptera: culicidae) in villages on the Kenya Coast I. Adult survivorship and population size.
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Aedes↗
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Effect of practice and patient population characteristics on the uptake of childhood immunizations.
BACKGROUND: The target-linked payments introduced by the 1990 general practitioners' contact were intended to reflect a close association between payments and performance in general practice. However, a straightforward direct relationship between service uptake in primary care and financial incentives should not be assumed. AIM: This study set out to examine the relationship between the factors which provide a broad profile of practices and general practitioners' performance in terms of primary childhood immunization targets. METHOD: Anonymized data on primary immunization uptake rates in 208 practices in Greater Glasgow Health Board and selected characteristics of the practices and their patient populations were analysed. RESULTS: Seventy five per cent of the practices in the study qualified for a high-target payment in the last quarter of the 1991-92 financial year, but only 53% managed to do so in all four quarters of the year. Tests of differences between means showed that the provision of child health surveillance, the notional' mortality ratio for each practice's patient population and the percentage of patients attracting deprivation payments were significant differentiating factors among the practices grouped according to immunization target achieved at 1 October 1991--high target, low target and neither. There was no evidence that the target achieved was significantly affected by the activity or clinical staffing levels of the practices--number of patients per general practitioner, number of practice nurses or being single handed. A disproportionate number of practices reaching the high target were located in the more affluent areas, whereas a higher than expected proportion of those which either achieved the low target or missed both targets was located in the more deprived areas. Similar results were obtained when the performance of the practices in achieving the high target over four consecutive quarters was considered. CONCLUSION: Practice serving populations living in socially deprived areas and with poorer health were less likely to achieve the high target for childhood immunizations. Evidence of repetition of performance in immunization uptake among the practices leads to concern over increased risk of infectious diseases among children from socially deprived populations who fail to be immunized. This seems to be yet another example of the inverse care law.
Child↗
Angina pectoris in a contemporary population: characteristics and therapeutic implications. TIDES Investigators.
We characterized a contemporary, nonhospitalized population with angina pectoris by obtaining data from a geographically diverse cohort of 5125 outpatients with chronic stable angina cared for by 1266 primary-care physicians. Diagnosis was based on history supported by evidence for coronary artery disease (coronary angiography, old myocardial infarction [MI], and/or an abnormal stress test). Their mean age was 69 years and 53% were women. Seventy percent had more than one associated illness, and 65% used more than one cardiovascular drug. Calcium antagonists (46%) and nitrates (61%) were used most frequently. Median angina frequency was approximately 2 episodes/week, and increased angina frequency was associated (P < 0.0001) with decreased overall feeling of well-being. Although effort angina was present in 90% of patients, 47% also had rest angina and 34% had mental stress-evoked angina. Female gender (odds ratio: 1.09; 95% CI: 1.02-1.16), concomitant illness (1.17, 1.09-1.25), and pharmacotherapy (1.14, 1.07-1.22) were associated with rest angina. Younger age (1.30, 1.20-1.41), female gender (1.16, 1.07-1.26), concomitant illness (1.13, 1.03-1.24), and pharmacotherapy (1.28, 1.15-1.93) were associated with mental stress angina. Calcium antagonists were used for rest-evoked (1.09, 1.03-1.16) and mental stress-evoked (1.12, 1.04-1.21) angina. These data suggest that contemporary outpatients with angina are most likely to be women and elderly patients with high frequencies of associated illness, calcium antagonist and nitrate use, as well as rest- and mental stress-related angina. These characteristics differ from previous perceptions.
Age Distribution↗
A priori lithium dosage regimen using population characteristics of pharmacokinetic parameters.
The important problem of initiation of long-term lithium treatment is tackled by means of the selection of an a priori dosage regimen based on the presumed efficacy of lithium and absence of toxicity. The pharmacokinetics of Li+ ion is represented by a four-compartment open model including the supposed first-order processes for the release of the active compound from the dosage form and its absorption. Experimental protocols for measurements of serum concentrations and of urinary amounts after single and multiple dosing to healthy volunteers were derived with several oral dosage forms. Estimation of the pharmacokinetic parameters for each subject made it possible to validate the model for the various dosage forms. The interindividual variability of these parameters is taken into account by estimating the characteristics of the statistical distribution for the whole population. A dosage regimen is considered optimum when serum concentration profiles at steady state range from the threshold of efficacy (0.8 mmol/liter) to the threshold of toxicity (2.0 mmol/liter). When the number of daily intakes is fixed, the search for the optimum dose for the whole population is effected by minimizing the expected value of the random variable which characterizes the risks of excursion out of the therapeutic range. By this means universal dosages are shown to be unsatisfactory. However, certain dosage regimens individualized with respect to the renal clearance value of lithium and based on two or three daily intakes can give excellent results even when conventional dosage forms are used.
Adolescent↗
On the dependence of speciation rates on species abundance and characteristic population size.
The question of the potential importance for speciation of large/small population sizes remains open. We compare speciation rates in twelve major taxonomic groups that differ by twenty orders of magnitude in characteristic species abundance (global population number). It is observed that the twenty orders of magnitude's difference in species abundances scales to less than two orders of magnitude's difference in speciation rates. As far as species abundance largely determines the rate of generation of intraspecific endogenous genetic variation, the result obtained suggests that the latter rate is not a limiting factor for speciation. Furthermore, the observed approximate constancy of speciation rates in different taxa cannot be accounted for by assuming a neutral or nearly neutral molecular clock in subdivided populations. Neutral fixation is only relevant in sufficiently small populations with 4N(e)v < 1, which appears an unrealistic condition for many taxa of the smaller organisms. Further research is clearly needed to reveal the mechanisms that could equate the evolutionary pace in taxa with dramatically different population sizes
Animals↗
Population characteristics predict responses in moose body mass to temporal variation in the environment.
1. A general problem in population ecology is to predict under which conditions stochastic variation in the environment has the stronger effect on ecological processes. By analysing temporal variation in a fitness-related trait, body mass, in 21 Norwegian moose Alces alces (L.) populations, we examined whether the influence of temporal variation in different environmental variables were related to different parameters that were assumed to reflect important characteristics of the fundamental niche space of the moose. 2. Body mass during autumn was positively related to early access to fresh vegetation in spring, and to variables reflecting slow phenological development (low June temperature, a long spring with a slow plant progression during spring). In contrast, variables related to food quantity and winter conditions had only a minor influence on temporal variation in body mass. 3. The magnitude of the effects of environmental variation on body mass was larger in populations with small mean body mass or living at higher densities than in populations with large-sized individuals or living at lower densities. 4. These results indicate that the strongest influence of environmental stochasticity on moose body mass occurs towards the borders of the fundamental niche space, and suggests that populations living under good environmental conditions are partly buffered against fluctuations in environmental conditions.
Animals↗
Geographic variability of hemophilia-associated AIDS in the United States: effect of population characteristics. Hemophilia-Associated AIDS Study Group.
National AIDS surveillance suggests that approximately 3.5% of all hemophilic patients in the United States have developed AIDS as of February 1988; however, the cumulative incidence of AIDS among seropositive patients at individual hemophilia treatment centers (HTCs) has been reported to be as high as 12%. The purpose of this study was to examine the reported excess risk of AIDS at selected HTCs. Between July 13 and November 6, 1987, we reviewed medical charts from the 598 hemophilia A and hemophilia B patients receiving comprehensive care as of 1980 at six U.S. hemophilia treatment centers (three identified as low AIDS risk and three identified as high AIDS risk using national hemophilia-associated AIDS surveillance data). The risk of AIDS among all patients was 8% and among seropositive patients was 18%. At the individual HTCs, the risk ranged from 0% to 14% among all patients and 0% to 25% among seropositive patients. Overall incidence rates were higher than those derived from national surveillance data because national estimates include all hemophilic patients (regardless of severity) whereas this study included only patients receiving comprehensive care (who are more likely to be severely affected by their coagulation disorder and receive concentrated clotting factors). The higher incidence of AIDS in the high-risk centers was attributable to the older age of the patients in these HTCs, a factor previously associated with an increased risk of AIDS in seropositive patients. These findings do not support geographic variability in the incidence of AIDS and emphasize the importance of patient characteristics when comparing the incidence of hemophilia-associated AIDS between populations.
AIDS Serodiagnosis↗
[Population characteristics of chronic ENT diseases prevalence in adults living in the North of the Eastern Siberia].
Characteristics of chronic ENT diseases in European migrants and native Mongoloid population of the East Siberian North have been analysed epidemiologically. Epidemiological differences and similarities between the above populations are explained by their immunogenetic peculiarities.
Adult↗
FSHD in Chinese population: characteristics of translocation and genotype-phenotype correlation.
Current studies of facioscapulohumeral muscular dystrophy (FSHD) are confined to the white population. The authors surveyed 110 healthy individuals and 27 families with FSHD including 55 patients and 74 relatives by pulsed-field gel electrophoresis. The authors report the characteristics of translocation and genotype-phenotype correlation, and their results indicate 4q to 10q translocation contributes to the occurrence of de novo mutation. This leads to a more severe phenotype in the Chinese population comparing to EcoRI allele sizes and the intersexual difference.
Adolescent↗
[Influence of population characteristics and dynamics on health problems].
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Chile↗
Taiwan's population characteristics and dynamics.
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Ethnicity↗
Population characteristics and the distribution of general medical practitioners.
By applying the logic of the Resource Allocation Working Party to the analysis of the distribution of general medical practitioners, the relevant Family Practitioner Committee (FPC) populations were weighted according to known patterns of use related to specific characteristics--namely, age, sex, marital state, and socioeconomic group. Comparative weightings were also calculated using standardised mortality ratios. Adjusting the populations to take account of differential use has relatively little impact on national variations in list sizes but an appreciable effect on particular FPCs, notably East and West Sussex, Dorset, and the Isle of Wight. Inequalities in the distribution of general practitioners are increased considerably, however, if figures taking account of the inflation of list sizes and cross-boundary flows are used. To formulate and monitor policy about the distribution of general practitioners more sensitive measures of population and its likely demand for services must be developed.
Adolescent↗
[Population characteristics of Coptis chinensis var. brevisepala in Anhui Province and its endangering mechanism].
The study on the distribution pattern, population size, and age structure of C. chinensis var. brevisepala in Anhui Province showed that C. chinensis var. brevisepala mainly distributed in the southern mountain areas such as Mts. Jiuhuashan, Guniujiang, Huangshan and Qingliang Peak. The habitats had two kinds, i.e., under woods and beside water ditches, both of which were shady and humid, with loose and acidic soils containing abundant organic matter. The shading degree surpassed 70%, air humidity reached 70% approximately 90%, and soil water content was more than 30%. The distribution pattern of existing C. chinensis var. brevisepala populations was clustering, with illogical age structure and small population size. It was suggested that the populations of C. chinensis var. brevisepala in Anhui Province were in an unsteady stage. Serious destroy of natural habitat and excessive digging and gathering adult individuals were the main causes of the rapid decrease of the individuals in some populations, which threatened the existence of C. chinensis var. brevisepala populations seriously.
Biodiversity↗
Worm population characteristics and pathological changes in lambs after a single or trickle infection with Teladorsagia circumcincta.
The regulation of the worm population and of its pathological effects was studied after a single or trickle infection with T. circumcincta. One hundred and twenty lambs, 60 Romanov and 60 Mérinos d'Arles, 3 months old, were distributed in four balanced groups: non-infected (G0), infected with 7000 L3 per animal once and slaughtered after 4 weeks (G14) or 8 weeks (G18), and infected 8 times and slaughtered after 8 weeks (G88). Parasitological, histological, haematological parameters and weight gains were recorded on each animal. Female and artificially nursed lambs had lower worm burdens and egg counts (epg) than males and naturally suckled lambs. No difference in parasitological parameters was seen between the two breeds, but Mérinos lambs infected once, had a higher increase in pepsinogen concentrations than Romanov lambs. In the infected animals, a significant proliferation of mast and eosinophil cells was observed in the abomasum wall. Serum pepsinogen concentrations were significantly higher 3 weeks p.i. and the weight gain was depressed during the first month p.i. The worm population was more numerous and younger in group G14 compared with G18 in which 24% of the worms had been expelled during the second month p.i. The female worms in G18 were longer and had more eggs in utero and higher egg output. After the trickle infection (G88) the take was reduced, female worms were longer with more eggs in vagina (pars ejectrix) and there was a higher variability in the number of eggs (compared with G18 data). The pepsinogen rise was smaller but no specific effect was seen on histological and haematological parameters.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Relations between individual life cycles and population characteristics.
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Birth Rate↗
[The effect of sodium nucleinate on the population characteristics of Streptococcus groups A and C].
The influence of sodium nucleinate on the growth kinetics, streptokinase activity and virulence of streptococcal populations, groups A and C, was studied. As revealed in these studies, the kinetics of the growth of the populations of both strains in the exponential phase did not depend on the concentration of sodium nucleinate in the culture medium. Measurements made on hours 15, 20 and 24 of growth showed the presence of close, direct and statistically significant correlation between the content of biomass, as well as streptokinase activity and specific streptokinase activity, and the concentration of sodium nucleinate in the culture medium. On the basis of the calculation of the coefficients of determination, the main part (70-96%) of the total dispersion of each of the above-mentioned characteristics dispersion of each of the above-mentioned characteristics could be attributed to variations in the concentration of sodium nucleinate. Five passages of faintly virulent streptococcal strains, groups A and C, were not accompanied by a rise in their virulence.
Animals↗
Benzodiazepine use in an elderly community-dwelling population. Characteristics of users and factors associated with subsequent use.
OBJECTIVES: The objective of this study was to describe determinants of current and subsequent benzodiazepine use in an elderly population, the Paquid cohort. METHODS: The study was conducted on a cohort of 2,792 community-dwelling subjects 65 years of age or more living in the Gironde department, southwestern France. Benzodiazepine use and its correlates were studied with data collected at inclusion in the cohort. Longitudinal analysis over a 5-year period of follow-up was done to identify baseline predictors of subsequent use. RESULTS: At baseline, prevalence rate of benzodiazepine use was 31.9%. It was associated with female gender [odds ratio (OR) = 2.0; 95% confidence interval (CI): 1.66, 2.46], previous psychiatric disease (OR = 2.87; 95% CI: 2.31, 3.56), concomitant antidepressant use (OR = 2.45; 95% CI: 1.59, 3.78), depressive symptomatology (OR = 1.70; 95% CI: 1.28, 2.26), multiple drug use (OR = 1.82; 95% CI: 1.50, 2.21), multiple chronic diseases (OR = 1.37; 95% CI: 1.12, 1.67) and poor self-perceived health (OR = 1.63; 95% CI: 1.33, 2.0). For the 1926 benzodiazepine non-users at inclusion and followed during 5 years, incidence rate of subsequent use was 5.37 per 100 person-years (95% CI: 4.76, 5.98). In multivariate Cox proportional hazards regression analysis, previous psychiatric diseases, poor self-perceived life satisfaction and polymorbidity were significantly associated with subsequent benzodiazepine use. CONCLUSIONS: Elderly people are heavy users of benzodiazepines. Independently from mental health status, those in poor health were most at risk of benzodiazepine use.
Aged↗
Nonparametric estimation of population characteristics of the kinetics of lithium from observational and experimental data: individualization of chronic dosing regimen using a new Bayesian approach.
A population analysis of the kinetics of lithium was performed from experimental and observational data in 113 subjects in order to propose a new approach for lithium dosage individualization. The kinetics of lithium is described by a two-compartment model. Age, body weight, height, and serum creatinine are included as covariates. Population analysis was performed by the nonparametric maximum likelihood method, which provides an estimate of the distribution of the five kinetic parameters and covariates. Mean lithium clearance was 1.50 L/h with a coefficient of variation (CV) of 38%, and was found to increase with body weight. Results were consistent with those of earlier studies and confirm a large interindividual variability. Data from a separate group of 35 patients were used to validate results: the estimated a priori and on covariate conditional distributions of the measured 24-h serum lithium concentration following a single dose were consistent with the corresponding measurements. A Bayesian approach for individualizing dosing schemes is proposed. This approach is based on minimization of a risk function expressing the deviation of the trough concentration at steady-state from the therapeutic range.
Adolescent↗