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Results for “Population Characteristics”

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At least 19 recordsLinked to original sources
PubMed1979

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↗
PubMed1979

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↗
PubMed1992

Effect of metronidazole on experimental periodontitis: cell population characteristics.

Systemic administration of metronidazole during an experimental periodontitis resulted in significantly less active tissue destruction compared to drug-free animals. However, the size of the inflammatory infiltrates in both groups was similar. The present study assessed cell populations within the infiltrates of metronidazole receiving and drug-free animals. In the experimental group, metronidazole was administered orally to 4 squirrel monkeys (100 mg/kg body weight per day) for 17 days. After 3 days, marginal periodontitis was induced around maxillary and mandibular bicuspids and molars by tying silk ligatures at the gingival margins. In 4 monkeys of the drug-free control group, periodontitis was induced around similar teeth. Biopsies of the gingiva representing 3, 7 and 14 days of experimental periodontitis were taken in both groups. The total number of cells and the number of polymorphonuclear leucocytes (PMN's) were counted on one-micron sections. At 3 days after ligature placement, there were numerically less total cells and PMN's in the metronidazole receiving experimental group. At 7 and 14 days the total number of cells and the number of PMN's was significantly greater in the drug-free control group, where more active periodontal breakdown had occurred. These results emphasize the potentially destructive role of PMN's in acute bursts of tissue destruction.

Animals↗
PubMed1992

Population characteristics of biological systems influenced by multicomponent random and uniform variation.

The total variability associated with the pharmacokinetic disposition of seven therapeutic agents was decomposed into its source components. After differentiating and isolating random components from fixed uniform components of variance, the proportional contribution of random intersubject and intrasubject variance was evaluated. Statistical analysis utilized a mixed-effects probabilistic model which incorporated both random effects and fixed day-to-day effects. In some cases, time-within-day diurnal effects were also incorporated. While significant intersubject effects were found for all seven drugs studied, three of them were characterized by predominant intrasubject variance. Since intrasubject variance represents a measure of the stability of drug disposition, characterization of its relative magnitude is fundamentally important in assessing the therapeutic consequences of a given treatment at any given time. Significant diurnal effects were found which were strikingly invariant.

Adult↗
PubMed1992

Population differences of fetal biophysical and behavioral characteristics.

Population differences in nonstress test reactivity have been reported with a threefold increase in the likelihood of nonreactive nonstress tests observed in black fetuses as compared with white fetuses. We analyzed fetal behavioral states and fetal heart rates in 14 black and 15 white fetuses at term to explain this observed difference in nonstress test reactivity. Two-hour Doppler and real-time ultrasonographic examination of each patient revealed no differences in percent time spent in the four behavioral states between the two populations. A 9.5 beats/min difference between black and white fetuses was found. The higher baseline heart rate of the black fetuses persisted in each behavioral state and may affect nonstress test reactivity because of rate-dependent decreases in short-term variability and rate-dependent limitations of maximal acceleration amplitude.

Behavior↗
PubMedDate not supplied

Biology of the human myeloma cell population. I.Macromolecular characteristics.

Several human myeloma cell populations were studied using a combination of cytochemical (Unna-Pappenheim and naphthol yellow staining, Feulgen reaction) and autoradiographical (uridine, leucine, thymidine uptake and actinomycin binding) techniques. Progressive differentiation of the myeloma population was associated with: 1. a loss of proliferative activity, 2. decreased transcriptional capacity, 3. decreased RNA and protein synthesis, 4. increased RNA and protein concentrations, 5. greater stability of the protein synthesis template. The existence of a pre-myelomatous compartment is suggested in the light of these results and those of previous kinetic studies in vivo.

Cell Cycle↗
PubMed1978

The factorial structure of the Personal Health Survey in normals and schizophrenics.

Administered the Personal Health Survey to five different groups: 74 incarcerated felons, 47 hospitalized alcoholics, 172 unmarried mothers, 51 college students, and 386 hospitalized chronic schizophrenics. On 191 of 200 items, the schizophrenics had higher base rates than any other group. Although some groups did not have large enough Ns for statistically adequate factor analyses, factorial studies also were done on the four control groups. Every group studied gave different factor patterns, with different orders of emergence of factors, different item loadings and heterogeneous composition of items. It is concluded that subgroups should be factored independently across time to determine population characteristics because overall population patterns do not make possible more than general predictions about subgroups. Individuals cannot be predicted from either overall or subgroup factorial characteristics.

Affective Symptoms↗
PubMed1991

Explaining outputs of primary health care: population and practice factors.

OBJECTIVE: To examine whether variations in the activities of general practice among family health service authorities can be explained by the populations characteristics and the organisation and resourcing of general practice. DESIGN: The family health services authorities were treated as discrete primary health care systems. Nineteen performance indicators reflecting the size, distribution, and characteristics of the population served; the organisation of general practice (inputs); and the activities generated by general practitioners and their staff (output) were analysed by stepwise regression. SETTING: 90 family health services authorities in England. MAIN OUTCOME MEASURES: Rates of cervical smear testing, immunisation, prescribing, and night visiting. RESULTS: 53% of the variation in uptake of cervical cytology was accounted for by Jarman score (t = -3.3), list inflation (-0.41), the proportion of practitioners over 65 (-0.64), the number of ancillary staff per practitioner (2.5), and 70% of the variation in immunisation rates by standardised mortality ratios (-6.6), the proportion of practitioners aged over 65 (-4.8), and the number of practice nurses per practitioner (3.5). Standardised mortality ratios (8.4), the number of practitioners (2.3), and the proportion over 65 (2.2), and the number of ancillary staff per practitioner (-3.1) accounted for 69% of variation in prescribing rates. 54% of the variation in night visiting was explained by standardised mortality ratios (7.1), the proportion of practitioners with lists sizes below 1000 (-2.2), the proportion aged over 65 (-0.4), and the number of practice nurses per practitioner (-2.5). CONCLUSIONS: Family health services authorities are appropriate systems for studying output of general practice. Their performance indicators need to be refined and to be linked to other relevant factors, notably the performance of hospital, community, and social services.

England↗
PubMed1977

The characteristics and mortality of outpatient-acquired pneumonia.

One-hundred fifty-four cases of pneumonia occurring over a 6-month period were analyzed. Population characteristics, admission diagnoses, causative pathogens, frequency of associated illnesses, antibiotic usage and mortality were evaluated. Despite population characteristics known to predispose to a poor clinical outcome, the mortality was low, probably because of rapid institution of a single, appropriate antibiotic.

Adult↗
PubMed1992

Regional variation in Medicare hospital mortality.

This study examines variation in severity-adjusted Medicare hospital mortality rates across nine U.S. census regions. The extent to which regional variation is reduced by controlling for differences in hospital resources and structure, county-level population characteristics, and the level of federal SuperPRO-identified hospital quality problems is estimated. Hospital resources, population characteristics, and SuperPro process quality scores are significant predictors of hospital mortality rates, but they do not explain the important, highly significant regional differences observed after controlling for hospital case-mix severity.

Centers for Medicare and Medicaid Services, U.S.↗