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PubMed1993

Evaluation of a nematode (Capillaria hepatica Bancroft, 1893) as a control agent for populations of house mice (Mus musculus domesticus Schwartz and Schwartz, 1943).

Sudden, large-scale infestations of house mice (Mus musculus domesticus) occur irregularly in the cereal-growing regions of Australia, resulting in substantial economic losses. Mathematical modelling has been used to evaluate the use of the liver nematode Capillaria hepatica as a potential agent for the biological control of mouse populations. The models suggest that C. hepatica is unlikely to be successful as a single-release control agent: instead, the parasite would need to be released when it becomes apparent that an outbreak is likely. Stage-structured models, including time delays and seasonal mouse demographic parameters, suggest that the parasite may be successful as a control agent, provided it can be introduced into the mouse population at least one year before an outbreak occurs. The optimum time for introduction is in summer or autumn. Some generalisations of this work are discussed. A parasite which affects fecundity alone is unlikely to be a good control agent, because it will destabilize the host population. Macroparasites may be unable to spread sufficiently rapidly to control sudden rises in vertebrate populations.

Animals↗
PubMed2001

Effect of probiotics on bacterial population and health status of shrimp in culture pond ecosystem.

The artificially manufactured probiotics having beneficial bacteria, Bacillus spp. was applied regularly in a modified extensive shrimp (Penaeus monodon) culture pond, located on the bank of Vellar estuary, Parangipettai. The populations of total heterotrophic bacteria (THB), beneficial bacteria (Bacillus spp.) and pathogenic bacteria (vibrios) were monitored in water and sediment of the pond. The results were compared with a control pond, situated in the same location having same water spread area, stocking density, species managed with same technologies and optimum environmental parameters in which no probiotic was applied. The populations of THB and Bacillus spp. in the experimental pond increased and the vibrios decreased after each application of probiotics. But the result of the control pond showed an increasing trend of the populations of THB, Bacillus spp. and vibrios towards days of culture. The control pond had lower levels of THB and Bacillus spp. and higher levels of vibrios than the probiotic applied (experimental) pond. Also the probiotics maintained optimum transparency and low organic load in the experimental pond as compared to control. In general, water and sediment had almost equal number of Bacillus spp. and vibrios, but sediment had higher THB load than water. The applications of probiotics lesser pathogenic vibrios and enhance beneficial bacilli in the culture leading to improved water quality, promoted growth and survival rates and increased the health status of the shrimp without stress and disease outbreaks. Thus the application of probiotics could lead to disease-free and profitable shrimp culture operations which will be helpful for shrimp farmers as most of them are now-a-days severely affected by microbial diseases.

Animals↗
PubMedDate not supplied

[Geographic variability in the sexually mature phase of Ixodes persulcatus (Ixodidae). Experience in using databases on morphometry].

The aim of the article is to estimate geographic variation of Ixodes persulcatus adults as a whole. Intraspecific variation of the females and males of Ixodes persulcatus Schulze, 1930 has been studied in eight geographical localities ("populations") of its distribution range (fig. 1.). The distance between western and eastern localities is more than 8700 km, between northern and southern ones it is approximately 2900 km. Twenty five to thirty specimens of each sex were studied in each geographical locality. The following eleven characters were used (fig. 2, 3): length of scutum (conscutum), width of scutum (conscutum), length of anal ring, width of anal ring, length of spiracular plate, width of spiracular plate, length of gnathosoma, width of gnathosoma, length of II-III articles of palps, length of hypostome, length of tarsus 1. The multidimensional scaling method by means of software package SYSTAT was used for estimation of relationships between populations on the basis of morphometrical data. The differences between the populations were revealed only from absolute sizes of organs, whereas their proportions (i. e. shape) were constant in all geographical localities. Fig. 4, 1 shows that females from localities G (Primorski Territory) and C (Tien Shan Mountains) occupy extreme positions. Fig. 4, 2 shows that males from localities G (Primorski Territory) and D (SW Altai Mountains) on the one hand and A, B (European) on the other one occupy extreme positions. Locality C (Tien Shan Mountains) is similar to F (Western Sayan Mountains) and to European (A, B) whereas females of locality C differ from A, B and F. Taking into account the partial discrepancy of relationships between populations in sexes we have united the data on corresponding characters of both sexes in the aggregate data base (fig. 4, 3). This was possible owing to the multidimensional scaling method. Fig. 4, 3 shows isolated position of the population G (Primorski Territory), specimens of which are the largest in sizes. The populations D (SW Altai Mountains) and H (Sakhalin Island) are morphometrically most similar to the population G. The population C (Tien-Shan Mountains) is represented of the smallest specimens. The European populations (A and B) are closer to C. The largest sizes are typical of the populations G and D associated with relict Tertiary landscapes of Primorski Territory and SW Altai with which areas of ecological optimum of I. persulcatus coincide. The smallest sizes are observed in the European populations (A, B) near the north-western boundary of the distribution range of the species, as well as in the Alpine population of Tien-Shan Mountains, near the upper vertical boundary of the distribution range (2000-3000 m above sea level). Climatic conditions of the habitat in these areas are similar to those of the northwestern part of the distribution range of I. persulcatus.

Animals↗
PubMed2004

Application of rational practice and technical advances for optimizing radiation dose for chest CT.

Though clinical benefits of CT exceed the adverse effects of radiation, the increasing use of CT has raised a compelling case for reducing radiation exposure. This controversy has been compounded by the sheer magnitude of CT examinations being performed annually, alleged overuse, and inappropriate selection of optimum scanning parameters, all of which expose the patient population to increased radiation exposure. Recommended clinical strategies for radiation dose optimization include optimization of scanning parameters and creating awareness and adopting guidelines for legitimate indications for CT scanning to avoid overuse and hence, the associated over-exposure. Whereas technological advances have increased the applications of the modality, it is also assisting in development of promising techniques to reduce associated radiation exposure, while maintaining "optimum image quality" needed to make a confident diagnosis. The present pictorial essay describes the fundamentals of CT radiation exposure and need for CT radiation dose reduction on the basis of documented scanning practices and technological advances.

Humans↗
PubMed1981

Stereological estimation of volume ratios by systematic sections.

Two related problems are explored. Firstly, a single opaque solid omega 2, is considered. The problem is to estimate the minimum number of systematic sections m, necessary to estimate the volume ratio v = V (omega 2)/V (omega 1) with a coefficient of error or at most gamma 0 with a probability 1 - alpha. Secondly, we consider a population of such specimens. The second problem is to estimate the optimum number of n of specimens to be sampled and the number n of systematic sections per specimen in order to estimate the mean volume ratio v of the population with a relative error of at most epsilon 0 with a probability 1 - alpha. General guidelines for solving the two problems are presented. Practical results applicable to two populations of mouse and guinea-pid lymph nodes, exhibiting a wide variation in size and shape, are obtained.

Animals↗
PubMed2001

Characterization of kidney epithelial cells from the Florida manatee, Trichechus manatus latirostris.

The West-Indian manatee, Trichechus manatus latirostris, is a herbivorous marine mammal found in the coastal waters of Florida. Because of their endangered status, animal experimentation is not allowed. Therefore, a cell line was developed and characterized from tissue collected during necropsies of the manatees. A primary cell culture was established by isolating single cells from kidney tissue using both enzymatic and mechanical techniques. Primary manatee kidney (MK) cells were subcultured for characterization. These cells were morphologically similar to the cell lines of epithelial origin. An immunocytochemistry assay was used to localize the cytokeratin filaments common to cells of epithelial origin. At second passage, epithelial-like cells had an average population-doubling time of 48 h, had an optimum seeding density of 5 x 10(3) cells/cm2, and readily attached to plastic culture plates with a high level of seeding efficiency. Although the epithelial-like cells had a rapid growth rate during the first three passages, the cloning potential was low. These cells did not form colonies in agar medium, were serum dependent, had a limited life span of approximately nine passages, and possessed cell-contact inhibition. These data suggest that the cells were finite (noncontinuous growth), did not possess transformed properties, and were of epithelial origin. These cells are now referred to as MK epithelial cells.

Animals↗
PubMed1980

Lead modelling--a decision-making tool.

The difficulties of decision-making in a state of ignorance regarding the problem area, true for many questions of environmental pollution, are discussed with reference to lead. Before irrevocably committing a considerable amount of both capital and material resources, the policy-making wound like to make a prediction as to the potential effectiveness of any control measure. To this end a mathematical model is suggested which represents the transport of lead within a standard man. It may be used at two discrete levels, either to analyse a number of control strategies in terms of their relative effectiveness in reducing blood lead concentrations, or, dependent upon the model's accuracy and the availability of data concerning the exposure to, and metabolism of, lead by a specific population, to select between two, or more, directly competing strategies for the control of that population's lead exposure, the selection of the optimum strategy being based on the model's output. Modelling may be seen, therefore, to satisfy, at least in part, the need for decision-making information in an area where time may not permit the acquisition of appropriate, unequivocable scientific evidence.

Cost-Benefit Analysis↗
PubMed2002

A global view of suicidal behaviour.

Suicidal behaviour is a major public health problem. There is no one explanatory theory of suicidal behaviour, and various combinations of sociological and biological/medical interventions are required to reduce associated mortality and morbidity. The importance of primary prevention varies from community to community, and may have an impact at the population level. However, individual suicidal persons always require optimum assessment and management and that is usually provided by primary care and emergency physicians. This paper provides an overview of issues to be addressed in the assessment and management of suicidal patients.

Adolescent↗
PubMedDate not supplied

Cognitive function in adult cardiothoracic transplant candidates and recipients.

Innovative surgical and medical techniques have prolonged the life span of cardiothoracic (CT) transplant recipients and made transplantation an option for many older patients. Cognitive function is a key determinant of the CT transplant recipient's ability to manage the complex treatment regimen and experience optimum benefit of the procedure. As the CT population ages, risk of cognitive dysfunction due to normal aging is compounded by the physical and mental changes associated with end-stage organ disease, comorbid conditions, and transplant-related complications. Cognitive abilities consist of (a) receptive functions (ability to select, acquire, classify, and integrate information); (b) memory and learning (ability to store and retrieve information); (c) thinking (ability to mentally organize and reorganize information; and (d) expressive functions (ability to communicate or act upon information). Although each of these functions represents a distinct type of behavior, they are interdependent. The purpose of this article is to (a) discuss the literature regarding cognitive function before and after adult heart, lung, and heart-lung transplantation; (b) identify methodological problems associated with the studies done to date; and (c) make recommendations for future research in this area.

Adaptation, Psychological↗
PubMed1987

Evaluation of a Bayesian method of amikacin dosing in intensive care unit patients with normal or impaired renal function.

Our study was designed to determine the population pharmacokinetic parameters of amikacin in intensive care unit patients and to develop a Bayesian method allowing individual estimation of pharmacokinetic parameters. A two-stage method was used for estimating the population characteristics of the pharmacokinetic parameters. Calculations of optimum doses and dosing intervals were based on individual parameters. Our results indicate that the Bayesian method is capable of estimating the individual pharmacokinetic parameters with no significant bias and good precision. Individualization of amikacin dosage was assessed 70 times in 52 patients. To determine the predictive performance of the method, observed peak and trough levels were compared with predicted values by computing precision, bias, and correlation. The amikacin dosing method was unbiased and showed a high correlation coefficient (r = 0.962) between measured and predicted drug serum concentrations. No significant differences were found between the predicted and observed peak (17.3 +/- 3.5 and 17.3 +/- 3.8 micrograms/ml, respectively) and trough (2.86 +/- 0.93 and 3.08 +/- 1.41 micrograms/ml, respectively) amikacin serum concentrations. Among the 52 patients, wide variations were observed in the pharmacokinetic parameters (Vd = 0.21-0.50 L/kg; t 1/2 = 1.1-22 h) and the daily doses (2.8-42 mg/kg/day).

Adolescent↗
PubMed1993

Digoxin pharmacokinetics in patients with high serum digoxin concentrations.

Digitalis intoxication is a frequent iatrogenic effect in patients on treatment with digoxin. In the present study we evaluated the pharmacokinetic behaviour of digoxin and the factors responsible for intoxication by this drug in monitored patients exhibiting clinical signs of overdosing with serum levels > 2 ng/ml. A control group of patients was used as a reference whose population pharmacokinetic parameters obtained by a maximum likelihood method were: Vd = 542.92 +/- 274.53 (litre); Cl = 8.73 +/- 1.55 (litre/h) (mean +/- SD). Statistically significant differences (P < 0.001) were found between the mean Cl values in both groups of patients. The difference between the dose-level ratios established in both populations studied also proved to be significant (P < 0.001). Calculation of the optimum dose for each patient showed that the doses recommended in intoxicated patients should be three times lower than those used in the control population. A good correlation was found between the concentrations observed 24 h after administration and the mean concentrations observed at steady state predicted for both population groups. Multiple regression analysis showed that the variables with the greatest predictive value for clearance in intoxicated patients were age and renal function. The modifications observed in the pharmacokinetic behaviour and in the response to digoxin in this type of patient suggest systematic monitoring using pharmacokinetic and clinical criteria jointly.

Adult↗
PubMed1998

The kinetic profile of vancomycin in neonates.

The pharmacokinetic parameters of vancomycin in a neonatal population have been characterized to enable development of optimum dosage guidelines for neonatal intensive-care units and to examine the relationship between these pharmacokinetic parameters and various demographic, developmental and clinical factors which might be associated with changes in the kinetic profile of vancomycin. Forty-four infants (twenty-five males and nineteen females) with suspected or proven Gram-positive infection and who received intravenous vancomycin between October 1993 and December 1996 were included in this retrospective analysis. Gestational age ranged from 25 to 40 weeks and postconceptional age at the time of the study ranged from 28 to 45 weeks. Sixty case-studies were obtained from the forty-four patients, with one period of study corresponding to one week or one cycle of therapy. Vancomycin pharmacokinetic parameters were determined by use of a one-compartment model. By regression analysis the current weight (g) was shown to be the stronger covariate, and both vancomycin clearance (L h(-1)) and volume of distribution (L) had to be normalized. The vancomycin volume of distribution depended on the postconceptional age with a cut-off at 32 weeks, whereas vancomycin clearance depended on the presence or absence of concomitant treatment with indomethacin or of mechanical ventilation, or both. On the basis of the pharmacokinetic parameters obtained we suggest initial dosage guidelines for vancomycin ranging from 10 mg kg(-1) every 8 h to 10 mg kg(-1) every 12 h, depending on the demographic and clinical characteristics of the patients. The results obtained enabled application of better a priori and a posteriori dosage schedules to infants in neonatal intensive-care units by use of the Bayesian approach, although further prospective study is recommended before direct extrapolation to patients in other settings.

Body Weight↗
PubMed1995

The invasive management of angina: issues for consumers and commissioners.

OBJECTIVE: To review, from the purchaser's perspective, the current state of knowledge of techniques for investigation and treating coronary artery disease. The study was based on evidence from past and continuing randomised controlled trials (RCTs). CRITERIA FOR INCLUSION OF REPORTS: Articles listed on Medline (1990-3) with the keywords coronary disease, angina, and unstable angina (combined with surgery, economics, therapy, or drug therapy) and percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) were included. Articles published before 1990 were obtained from two comprehensive literature reviews published by the Rand organisation in 1991 and from the papers obtained using the Medline search. A hand search of relevant journals published between July 1993 and June 1994 was also undertaken. Results from more recently published RCTs are included. RESULTS: CABG provides improved angina relief compared with drug treatment and may prolong life in patients with more severe illness. PTCA is also better than drug treatment, but less so than CABG, and its cost advantages over CABG decrease with time. Repeat intervention for return of symptoms is more frequently required after PTCA, but increasing numbers of patients are also undergoing second and third repeat CABG for graft occlusion in the years after the original operation. Newer PTCA techniques are not, as yet, fully evaluated. One technique, atherectomy, has been shown to be no more effective, and more expensive, than conventional balloon angioplasty. In the short term intracoronary stents reduce the problems associated with vessel occlusion after PTCA and therefore reduce the need for further intervention. PTCA should not be performed without ready access to cardiothoracic support. There is an increasing trend towards the development of coronary catheterisation units at peripheral sites. This may lead to increasing, inappropriate use of this investigation in suboptimal circumstances. CONCLUSIONS: Ischaemic heart disease is an important cause of morbidity and mortality and invasive management techniques are developing rapidly; some service expansion is occurring without trial evidence. More research is required to determine the optimum balance of PTCA, CABG, and angiography and population requirements for these procedures. In the meantime, in the absence of firm long term evidence of the superior cost effectiveness of PTCA compared with CABG, the rapid expansion of this procedure should be limited. Patients should be fully informed of the benefits and disadvantages of CABG and PTCA, where either procedure is indicated, to enable them to make fully informed choices.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

High school football injuries: identifying the risk factors.

This epidemiologic survey of the literature on the factors contributing to the high number of high school football injuries consolidates the current information on the characteristics and risk factors associated with these injuries. To reduce the incidence of knee sprains and strains, the most common injuries to this population, the following preventive recommendations are presented: 1) optimum maintenance of playing fields; 2) use of the soccer-style shoe; 3) noncontact and controlled activities in practice sessions; and 4) increased vigilance over technique during injury-prone preseason practices. The authors conclude that more research into factors such as exposure time and activity at injury will further reduce the risk to the high school football player.

Adolescent↗
PubMed1988

High school football injuries: identifying the risk factors.

This epidemiologic survey of the literature on the factors contributing to the high number of high school football injuries consolidates the current information on the characteristics and risk factors associated with these injuries. To reduce the incidence of knee sprains and strains, the most common injuries to this population, the following preventive recommendations are presented: 1) optimum maintenance of playing fields; 2) use of the soccer-style shoe; 3) noncontact and controlled activities in practice sessions; and 4) increased vigilance over technique during injury-prone preseason practices. The authors conclude that more research into factors such as exposure time and activity at injury will further reduce the risk to the high school football player.

Adolescent↗
PubMed1993

Economic values of optimum traits: the example of meat quality in pigs.

In this paper a method is outlined to derive marginal-income functions and to calculate economic values for traits with an intermediate optimum such as meat-quality traits. A normal distribution of the quality trait was assumed, but the method can be used for other distributions as well. The parameters necessary to use this method are distribution of the quality trait, population mean and the standard deviation of the quality trait, optimum range, and price differences between products within and outside the optimum range. Especially, the optimum range for the quality trait and the price differences to be used have to be derived from consumer and processing research. Some alternative methods that can be used for selection on quality traits, such as restricted selection index, desired-gains index, and indices based on a quadratic aggregate genotype, are discussed.

Animals↗
PubMed1991

Misoprostol and dalargin for the inpatient treatment of duodenal ulcer in the USSR.

In the USSR, uncomplicated duodenal ulcer is usually managed in an inpatient setting. A double-blind, randomized, double-dummy, multiclinic, comparative trial examined the safety and efficacy of oral misoprostol (200 micrograms qid) and intramuscular dalargin (1 mg bid) in duodenal ulcer healing. Dalargin, an enkephalin peptide with gastric antisecretory and cytoprotective properties, is commonly used in the USSR for treating peptic ulcer. The trial characteristics and monitoring were performed in accordance with US standards. Consenting patients of either sex, aged 18 to 70 years, who had a duodenal ulcer of 0.3 to 2.5 cm in diameter were enrolled. Endoscopy, physical examination, and laboratory assessments were performed on entry and after 4 weeks of treatment. The effects of the treatments on complete ulcer healing, dyspeptic symptoms, antacid consumption, adverse drug reactions, and safety were determined. Both treatment groups were well matched for demographic characteristics. The majority of patients were smokers and alcohol users and had a history of recurrent peptic ulcers. Misoprostol was significantly more effective than dalargin in inducing duodenal ulcer healing, both in the intent-to-treat cohort (P = .001) and in the evaluable cohort (P = .0001). Both regimens were well tolerated, and no patients were withdrawn from the study because of adverse reactions. Mild, self-limiting diarrhea was reported more frequently in patients receiving misoprotol (9.4% incidence) than those receiving dalargin (1.9%). The disparity in ulcer healing between the two groups suggests that hospitalization alone is not an optimum treatment in this high-risk patient population.

Adolescent↗
PubMed1986

[Manifestations of angina morbidity as a reflection of the self-regulation of the epidemic process in streptococcal infection].

The data on the application of the principles of the self regulation of the epidemic process for understanding the annual dynamics of angina morbidity in organized groups of adults are presented. In this case the reservation of group A streptococci occurs in chronic (resident) carriers, whose proportion was found to be 15.8 +/- 2.6%. The epidemic manifestations of morbidity are regulated mainly by the concentration of newly arrived members in the groups, i. e. by the size of the stratum providing the optimum conditions for the parasitization of the streptococcal population. The annual morbidity levels depend essentially not only on the heterogeneity of the group members with respect to their susceptibility to streptococcal infection, but also on the conditions of their accommodation, affecting the transmission of droplet infection. The role of individual risk factors in the variation of the quantitative characteristics of the angina morbidity manifestations under study is calculated.

Adult↗