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At least 685 records · Page 38Linked to original sources
PubMed1989

Rational use of diagnostic imaging in paediatrics. The report of a World Health Organization Study Group.

The World Health Organization (WHO) is the agency of the United Nations with primary responsibility for international health matters and public health. Through the exchange of the knowledge and experience of health professionals from 165 nations WHO promotes comprehensive health services worldwide. As a part of this effort WHO has in recent years been concerned with improving the availability and utilization of diagnostic imaging, especially as it relates to health services in developing countries. Having devised and specified suitable basic radiographic equipment (the WHO BRS) a WHO Scientific Group was convened in 1982 to study the utilization of radiographic procedures and to to recommend their more efficacious and rational use. Then in 1984, recognizing the implications of newer imaging technology on world health, a second WHO Scientific Group considered the design, impact and future use of ultrasonography and computed tomography in developing countries. The findings of these scientific groups were published as part of the WHO Technical Report Series which makes available the recommendations of such international groups of experts. Although some of the needs of children were considered in these previous Technical Reports, WHO felt that the size and socioeconomic importance of the paediatric population worldwide warranted a further study and report to address the particular technical and clinical problems of diagnostic imaging in the paediatric age group. Thus a third WHO Scientific Group met in Geneva from 18 to 24 November 1985 to review established practices and experience in paediatric imaging throughout the world; and to recommend rational guidelines for diagnostic imaging for children to age 14 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1999

Markers to analyse the prescribing of non-steroidal anti-inflammatory drugs in ambulatory care. A guide to pursuing rational and safe prescribing.

OBJECTIVE: The aim of the study is to construct quality markers for rational prescribing of non-steroidal anti-inflammatory drugs (NSAIDs MO1A, MO1B) in such a manner that they meet three requirements: suitability to be assessed by prescription analysis, application in feedback strategies and contribution to the task of internal quality assurance. METHOD: Eight different markers for validating NSAID prescribing were developed according to pharmacological literature. The prescribing of 99 participants (high prescribers) and 15 coordinators of eight pharmacotherapy circles (second quarter 1996) served as the database. To test the validity of the markers in terms of rationality, the NSAID prescribing of 15 randomly selected participants of these circles, whose participants were not trained in the analysis of their prescribing, was compared with the prescribing of the 15 coordinators of these circles, who had considerable experience in pharmacotherapy and group auditing. In order to compare results according to the age and sex of the patients, the two groups treated with NSAIDs were also matched (460 patients in each group). The drugs are classified under the ATC code with the volume given in defined daily doses (DDDs). RESULTS: Marker 1 - the percentage of NSAID DDDs for recommended drugs, i.e. ibuprofen, diclofenac, indomethacin and naproxen was significantly higher for the coordinators in comparison with the high prescribers (P < 0.05). Therefore, marker 3 (drugs with questionable efficacy) and marker 5 ('me-too' drugs) show an inverse relation. Drugs with a long half-life (marker 2), high-risk drugs (marker 4) and newly marketed drugs (marker 6) were all seldomly prescribed by both groups of doctors. There was no difference between the two groups of prescribers concerning the proportion of elderly people treated with NSAIDs (marker 7). With reference to marker 8 - co-medication with anti-ulcer drugs - the coordinators treated 8.9% of NSAID patients with antacids and anti-ulcer drugs, the high prescribers, on the other hand, treated 12.2% (NS). CONCLUSION: The markers can be easily assessed using the information obtained from drug claims and shown to each doctor personally. They call for the doctors to pay special attention to their particular drug selection. The markers can be implemented into feedback strategies of prescribing habits.

Ambulatory Care↗
PubMed2004

Influence of diet and ration level on benzo[a]pyrene metabolism and excretion in rainbow trout (Oncorhynchus mykiss).

Juvenile rainbow trout (Oncorhynchus mykiss) were fasted or fed one of three isoenergetic diets varying in protein and lipid content at full satiation levels or half rations for up to 9 weeks. At 3, 6, and 9 weeks, fish in each treatment group were dosed intraperitoneally with 10 mg tritiated benzo[a]pyrene [3H]-B[a]P/kg (B[a]P) to examine the effects of diet composition and energy intake on xenobiotic biotransformation and excretion. The percent dose eliminated during the experiment did not differ among fish receiving the different diet compositions or rations (range 73% to 84%). However, it was significantly decreased (to 53%) in the group that was fasted for 9 weeks. Examination of fish fasted for 6 and 9 weeks showed a significant increase in the proportion of phase I metabolites and a concomitant decrease in the proportion of phase II metabolites found in bile compared with all other groups. Also, fish that were fasted for 9 weeks produced proportionately less 9,10-dihydroxy-benzo[a]pyrene-trans-9,10-diol, more 3-hydroxybenzo[a]pyrene and 9-hydroxybenzo[a]pyrene, and more glucuronic acid conjugates compared with all other groups. Thus, dietary protein and lipid concentration did not appear to affect either the rate of B[a]P metabolism or its excretion; however, prolonged fasting resulted in a shift in metabolite profiles and decreased excretion.

Animal Feed↗
PubMed2003

Toward rational control of Escherichia coli O157:H7 by a phage cocktail.

Twenty six phages infected with Escherichia coli O157:H7 were screened from various sources. Among them, nine caused visible lysis of E. coli O157:H7 cells in LB liquid medium. However, prolonged incubation of E. coli cells and phage allowed the emergence of phage-resistant cells. The susceptibility of the phage-resistant cells to the nine phages was diverse. A rational procedure for selecting an effective cocktail of phage for controlling bacteria was investigated based on the mechanism of phage-resistant cell conversion. Deletion of OmpC from the E. coli cells facilitated the emergence of cells resistant to SP21 phage. After 8 h of incubation, SP21-resistant cells appeared. By contrast, alteration of the lipopolysaccharide (LPS) profile facilitated cell resistance to SP22 phage, which was observed following a 6-h incubation. When a cocktail of phages SP21 and SP22 was used to infect E. coli O157:H7 cells, 30 h was required for the emergence of cells (R-C) resistant to both phages. The R-C cells carried almost the same outer membrane and LPS components as the wild-type cells. However, the reduced binding ability of both phages to R-C cells suggested disturbance of phage adsorption to the R-C surface. Even though R-C cells resistant to both phages appeared, this work shows that rational selection of phages has the potential to at least delay the emergence of phage resistance.

Adsorption↗
PubMed2001

Primary breast tumor levels of suspected molecular determinants of cellular sensitivity to cyclophosphamide, ifosfamide, and certain other anticancer agents as predictors of paired metastatic tumor levels of these determinants. Rational individualization of cancer chemotherapeutic regimens.

PURPOSE: Cyclophosphamide is one of the most frequently used agents in the neoadjuvant, adjuvant, and high-dose chemotherapeutic treatment of breast cancers. Preclinical models indicate that cellular sensitivity to cyclophosphamide and other oxazaphosphorines, e.g., ifosfamide, is inversely related to the cellular content of two aldehyde dehydrogenases, viz ALDH1A1 and ALDH3A1, and glutathione. Breast tumor levels of these "determinants of cellular sensitivity to the oxazaphosphorines" are known to vary widely, and the decision as to whether or not to use an oxazaphosphorine as part of the therapeutic strategy to treat breast cancer in any given patient is likely to depend, in large part, on the levels of these determinants in that cancer. ALDH1A1, ALDH3A1, and glutathione levels can be easily quantified in primary breast tumors and in detectable metastatic breast tumors present in axillary lymph nodes because the amounts of tissue required for the desired analysis can be readily obtained, whereas these levels cannot be quantified in residual metastatic breast cancer cell populations, i.e., those that escape detection and/or that are inaccessible to surgical harvest. The inability to directly quantify residual metastatic breast cancer cell ALDH1A1, ALDH3A1, and glutathione levels would not preclude a rational decision with regard to the inclusion/exclusion of an oxazaphosphorine as part of the chemotherapeutic strategy intended to eradicate residual metastatic breast cancer cells if primary breast tumor levels of these determinants reliably predicted those in metastatic breast cancer cells. METHODS: ELISAs and spectrophotometric assays were used to quantify enzyme and glutathione levels in paired human primary and locally advanced metastatic breast tumor samples. RESULTS: Primary breast tumor ALDH1A1 and ALDH3A1 levels were highly predictive of their respective levels in paired metastatic breast tumors present in axillary lymph nodes (r2 = 0.80 and 0.85, respectively). On the other hand, those of glutathione were relatively poorly predictive of its levels in paired metastatic offshoots (r2 = 0.35). Primary breast tumor levels of some additional enzymes known to catalyze the detoxification/toxification of various anticancer agents, though not of cyclophosphamide, were poorly predictive (DT-diaphorase and glutathione S-transferases alpha, mu, and pi) or not predictive (cytochrome P450 1A1) of their respective levels in paired metastatic offshoots. CONCLUSION: Since ALDH1A1, ALDH3A1 and, to a lesser extent, glutathione levels in primary breast tumors reliably predicted those in detectable and easily accessible metastatic breast cancer cell populations, viz those in axillary lymph nodes, they are also likely to be predictive of these levels in undetectable and/or relatively inaccessible metastatic breast cancer cell populations. Thus, quantification of primary breast tumor ALDH1A1, ALDH3A1 and, to a lesser extent, glutathione levels prior to the initiation of not only neoadjuvant but also adjuvant and high-dose breast cancer chemotherapy is likely to be of value in the rational design of individualized chemotherapeutic regimens intended to eradicate breast cancer cells with a minimum of untoward effects.

Aldehyde Dehydrogenase↗
PubMed2000

On the option interpretation of rational harvesting planning.

We consider the determination of the harvesting strategy maximizing the present expected value of the cumulative yield from the present up to extinction. By relying on a combination of stochastic calculus, ordinary nonlinear programming, and the classical theory of diffusions, we show that if the underlying population evolves according to a logistic diffusion subject to a general diffusion coefficient, then there is a single threshold density at which harvesting should be initiated in a singular fashion. We derive the condition which uniquely determines the threshold and show that harvesting should be initiated only when the option value of further preserving another individual falls below its opportunity cost. In this way, we present a real option interpretation of rational harvesting planning. We also consider the comparative static properties of the value of the harvesting opportunity and state a set of usually satisfied conditions under which increased stochastic fluctuations (demographic or environmental) decrease the expected cumulative yield from harvesting and increase the optimal harvesting threshold, thus postponing the rational exercise of the irreversible harvesting decision.

Animals↗
PubMed2005

Non-stochastic and stochastic linear indices of the molecular pseudograph's atom-adjacency matrix: a novel approach for computational in silico screening and "rational" selection of new lead antibacterial agents.

A novel approach (TOMOCOMD-CARDD) to computer-aided "rational" drug design is illustrated. This approach is based on the calculation of the non-stochastic and stochastic linear indices of the molecular pseudograph's atom-adjacency matrix representing molecular structures. These TOMOCOMD-CARDD descriptors are introduced for the computational (virtual) screening and "rational" selection of new lead antibacterial agents using linear discrimination analysis. The two structure-based antibacterial-activity classification models, including non-stochastic and stochastic indices, classify correctly 91.61% and 90.75%, respectively, of 1525 chemicals in training sets. These models show high Matthews correlation coefficients (MCC=0.84 and 0.82). An external validation process was carried out to assess the robustness and predictive power of the model obtained. These QSAR models permit the correct classification of 91.49% and 89.31% of 505 compounds in an external test set, yielding MCCs of 0.84 and 0.79, respectively. The TOMOCOMD-CARDD approach compares satisfactorily with respect to nine of the most useful models for antimicrobial selection reported to date. Finally, an in silico screening of 87 new chemicals reported in the anti-infective field with antibacterial activities is developed showing the ability of the TOMOCOMD-CARDD models to identify new lead antibacterial compounds.

Algorithms↗
PubMed2003

Should one use smokeless tobacco in smoking cessation programs? A rational addiction approach.

The rational addiction model is often used for empirical analysis of the demand for addictive goods. We propose an extension of the model to include two goods, cigarettes and Swedish moist snuff, locally known as snus. Demand equations are estimated using aggregated annual time series data (in first differences) for the period 1964-1997. The findings from the dataset used give some support to the rational addiction hypothesis. The cross-price elasticities are negative, which indicates that taking snus contributes to increased smoking. Thus it is not advisable to encourage the use of the less harmful snus in smoking cessation programs.

Journal Article↗
PubMed2006

Rational design of a dual-mode optical and chemical prodrug.

PURPOSE: The purpose of this study is to demonstrate the rational design and behaviour of the first dual-mode optical and chemical prodrug, exemplified by an acetyl salicylic acid-based system. METHODS: A cyclic 1,4-benzodioxinone prodrug was synthesised by reaction of 3,5-dimethoxybenzoin and acetyl salicoyl chloride with pyridine. After purification by column chromatography and recrystallization, characterization was achieved using infrared and NMR spectroscopies, mass spectrometry, elemental analysis and single crystal X-ray diffraction. Light-triggered drug liberation was characterised via UV-visible spectroscopy following low-power 365 nm irradiation for controlled times. Chemical drug liberation was characterised via UV-visible spectroscopy in pH 5.5 solution. RESULTS: The synthetic method yielded pure prodrug, with full supporting characterisation. Light-triggered drug liberation proceeded at a rate of 8.30x10(-2) s-1, while chemical, hydrolytic liberation proceeded independently at 1.89x10(-3) s-1. The photochemical and hydrolytic reactions were both quantitative. CONCLUSIONS: This study demonstrates the first rational dual-mode optical and chemical prodrug, using acetyl salicylic acid as a model, acting as a paradigm for future dual-mode systems. Photochemical drug liberation proceeds 44 times faster than chemical liberation, suggesting potential use in drug-eluting medical devices where an additional burst of drug is required at the onset of infection.

Aspirin↗
PubMed1996

Domain-specific rationality in human choices: violations of utility axioms and social contexts.

This study presents a domain-specific view of human decision rationality. It explores social and ecological domain-specific psychological mechanisms underlying choice biases and violations of utility axioms. Results from both the USA and China revealed a social group domain-specific choice pattern. The irrational preference reversal in a hypothetical life-death decision problem (a classical example of framing effects) was eliminated by providing a small group or family context in which most subjects favored a risky choice option regardless of the positive/negative framing of choice outcomes. The risk preference data also indicate that the subjective scope of small group domain is larger for Chinese subjects, suggesting that human choice mechanisms are sensitive to culturally specific features of group living. A further experiment provided evidence that perceived fairness might be one major factor regulating the choice preferences found in small group (kith-and-kin) contexts. Finally, the violation of the stochastic dominance axiom of the rational theory of choice was predicted and tested. The violations were found only when the "life-death" problem was presented in small group contexts; the strongest violation was found in a family context. These results suggest that human decisions and choices are regulated by domain-specific choice mechanisms designed to solve evolutionary recurrent and adaptively important problems.

Adult↗
PubMed1981

Speech-rhythm characteristics of client-centered, Gestalt, and rational-emotive therapy interviews.

The aim of this study was to discover whether client-centered, Gestalt, and rational-emotive psychotherapy interviews could be described and differentiated on the basis of quantitative measurement of their speech rhythms. These measures were taken from the sound portion of a film showing interviews by Carl Rogers, Frederick Perls, and Albert Ellis. The variables used were total session and percentage of speaking times, speaking turns, vocalizations, interruptions, inside and switching pauses, and speaking rates. The three types of interview had very distinctive patterns of speech-rhythm variables. These patterns suggested that Rogers's Client-centered therapy interview was patient dominated, that Ellis's rational-emotive therapy interview was therapist dominated, and that Perls's Gestalt therapy interview was neither therapist nor patient dominated.

Gestalt Therapy↗
PubMed1993

Rationality, emotional expression and control: psychometric characteristics of a questionnaire for research in psycho-oncology.

In some studies rationality, anti-emotionality and the control of (negative) emotions were found to be psychological risk factors for cancer. In the present study instruments were developed in order to cross-validate the role of the 'rationality/anti-emotionality (RAE)'-concept and the 'emotional expression and control (EEC)'-concept. The psychometric characteristics of a RAE-scale and EEC-scales were investigated in 4302 healthy women attending a breast cancer screening programme in The Netherlands. Principal components analysis revealed three factors for the RAE-scale: (1) Rationality; (2) Emotionality; and (3) Understanding. The EEC-scales consist of three factors that indicate: (1) expression of emotions to oneself; (2) expression of emotions towards others; and (3) control of emotions. These RAE and EEC scales can be of importance in psycho-oncological research, especially when: (1) the more refined subscales are used; and (2) age of the subjects is taken into account.

Adult↗
PubMed1983

Utility and decision strategies: a second look at the rational decision maker.

The concept of bounded rationality underlies most behavioral, descriptive decision theory. The implications of limited cognitive capacity have been extensively explored; however, there have been few attempts to understand the means by which decisions made under these constraints remain rational. Some propositions with regard to the ways in which utility considerations guide decision strategies are presented and tested. The results provide some evidence that the decision maker uses strategies that are relatively likely to enhance the utility of the final choice, even when utility maximization is not feasible.

Career Choice↗
PubMed1993

Empirical and rational approaches for development of inhibitors of the human immunodeficiency virus--HIV-1.

The human immunodeficiency virus, HIV-1, is generally accepted to be responsible for AIDS. It is imperative that all approaches, empirical and rational, be taken for development of a drug for therapy of this disease. These approaches are discussed, with emphasis on the direction being pursued in our laboratory. Empirically, we found 3'-deoxy-2',3'-didehydrothymidine, a compound first synthesized for potential anticancer activity by J. Horwitz in the 1960s, to be a potent inhibitor of HIV-1. It is now in Phase II/III clinical trials. We have also synthesized several 2,5'-anhydro pyrimidine nucleoside analogs, which have interesting chemical and biological properties. We have evaluated a natural product, gossypol and synthesized various derivatives for anti-HIV-1 activity, but none were appreciably more inhibitory than the parent compound. More recently, we have taken the rational approach and synthesized a boron-modified tetrapeptide, Ac-Thr-Leu-Asn-boro-Phe, which corresponds to the COOH-terminal of the Phe-Pro scissle bond of the gag/pol gene polyprotein product. Potent inhibition of the HIV-1 encoded protease was observed. These approaches and findings will be discussed.

Amino Acid Sequence↗
PubMed1987

Non-price rationing and the choice of medical care providers in rural Côte d'Ivoire.

This paper investigates the role of travel time in rationing medical care services in a developing country where monetary prices are zero. A nested multinomial logit model of provider choice is estimated using 1985 data from rural Côte d'Ivoire. Unlike previous studies of health care demand in developing countries, our results indicate that travel time plays an important role in rationing health care, and that medical care demand for poorer individuals is substantially more travel time elastic than for richer individuals.

Africa↗
PubMed1987

In search of economic rationality: the experience of the Polish National Health Service.

This paper discusses the problems of the use of economic incentives as a management tool in the Polish National Health Service, in which the economic approach had long been regarded as morally improper. Health, an important ethical value, was not to be defiled by direct contact with economic realities. It was only in the early 1980's that it was accepted that the non-economic approach had been destructive for both the performance and the moral climate of the NHS. Significant defects in the previous solutions stimulated a great effort to reorient and rationalize the system. In the 1940's when the Polish NHS was established, it was decided to abolish economic barriers to health care, the free access to which was perceived as essential to socialist health care. While utilization increased, access was still restricted, although not by formal barriers but by scarcity of resources. The situation became all the more painful because a general expectation of easily obtainable health services had been aroused. The health sector as a whole was underfinanced; health professionals were underpaid in comparison with professionals in other sectors; the salary system severed the link between input and reward. More productive individuals took extra jobs in the NHS and outside it, thus threatening the quality of the service. A number of rationalization measures have been taken. Special premiums, combinations of capitation and fee-for-service, new financing mechanisms, and forms of patient cost-sharing are being experimented with or considered.

Community Participation↗
PubMed1987

Drug prescribing: a discussion of its variability and (ir)rationality.

Drugs have become an essential part of modern health care. An ever increasing quantity of drugs contributes to people's health. Yet, when unwisely used, drugs may also entail adverse effects and can damage health. Inappropriate or irrational prescription behavior has been reported in the literature. In this paper, I argue that this behavior is a by-product of the variability in prescribing, and make an attempt to understand this variability. Subsequently, the phenomenon of (ir)rational prescribing is studied. A distinction is made between three forms of rationality: that of the physician, the pharmacologist, and the patient. Policy suggestions aiming at improving patients' welfare are offered as well. Three controversial issues in drug prescribing are further discussed, namely the role of advertising, brand names and product variety.

Decision Making↗
PubMed1996

Are decisions taken by health care professionals rational? A non systematic review of experimental and quasi experimental literature.

Systematic overviews of the effectiveness and cost effectiveness of health care interventions are increasingly available, and yet there has been relatively little attention upon putting their important findings into practice. Furthermore, close attention to the decision making behaviour of health professionals in situations of uncertainty indicates that this may not always be 'rational'. This paper examines developments in the understanding of rationality in decision making from outside the health care setting, particularly the interesting work on 'regret theory', and begins to apply this framework to health care.

Cost-Benefit Analysis↗