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PubMed1997

Information needs and decisional preferences in women with breast cancer.

OBJECTIVE: To determine the degree of involvement women with breast cancer wanted in medical decision making, extent to which they believed they had achieved their preferred level of involvement, and types of information they judged to be most important. DESIGN AND SETTING: Cross-sectional survey at 2 tertiary oncology referral clinics and 2 community hospital oncology clinics in Winnipeg, Manitoba. PATIENTS: Consecutive sample of 1012 women with a confirmed diagnosis of breast cancer who were scheduled for a visit at 1 of 4 hospital oncology clinics. MAIN OUTCOME MEASURES: The following measures were used: (1) Preferences about various levels of participation in treatment decision making; (2) the extent to which subjects believed they had achieved their preferred levels of involvement in decision making; and (3) priority needs for information and how these needs differed by selected sociodemographic, disease, and treatment variables. RESULTS: A total of 22% of women wanted to select their own cancer treatment, 44% wanted to select their treatment collaboratively with their physicians, and 34% wanted to delegate this responsibility to their physicians. Only 42% of women believed they had achieved their preferred level of control in decision making. The 2 most highly ranked types of information were related to knowing about chances of cure and spread of disease. Women younger than 50 years rated information about physical and sexual attractiveness as more important than did older women (P<.001); women older than 70 years rated information about self-care as more important than did younger women (P=.002); and women who had a positive family history of breast cancer rated information about family risk as more important than did other women (P=.03). CONCLUSIONS: The substantial discrepancy between women's preferred and attained levels of involvement in treatment decision making suggests that systematic approaches to assess and respond to women's desired level of participation in treatment decision making need to be evaluated. Priorities for information identified in this study provide an empirical basis to guide communication with women seeking care for breast cancer.

Adult↗
PubMed1998

Breaking bad news. 2: What evidence is available to guide clinicians?

Literature related to breaking bad news to medical patients was reviewed. An analysis of citations appearing between 1994 and August 1997 updated earlier work and indicated that a minority (24%) of the studies on the subject were designed to collect original data. Ten randomized controlled trials (RCTs) evaluating communication strategies with cancer patients in the diagnostic phase have been published since 1980. These RCTs were analyzed for methodological adequacy and their clinical implications. The sampling methods of the RCTs presented particular problems. Although patients liked the experimental interventions, there was little evidence of any effect on the patients' psychological adjustment; the effects on patients' knowledge and satisfaction levels were inconsistent. Healthcare consequences of issues concerned with patient selection, cultural factors, medical-legal requirements, and intervention costs are outlined and specific suggestions offered for future research testing the effects of different approaches to breaking bad news.

Adaptation, Psychological↗
PubMed1989

Childhood depression: problems of definition.

The occurrence of depressive disorders in children is a problematic and confusing issue, and it is uncertain whether such behavior should be regarded as manifestations of depression so regarded in adults. Studies of childhood depression might benefit from approaches considering developmental differences in the patterning of depressive manifestations. Use of adult diagnostic criteria and premature disregard of developmental differences may impede accurate study and diagnoses of childhood depression. Empirical, multivariate approaches could be used to investigate symptom groupings to confirm existing diagnostic criteria, or stimulate adjustment of these criteria to identified developmental differences.

Adolescent↗
PubMed2000

Preventing HIV infection through sexual-behavior change.

Research on HIV prevention during the past decade has identified numerous models, at levels ranging from individual interventions to public policies capable of affecting an entire population. None of these approaches should be considered sufficient in itself because, put simply, behavior is difficult to modify. This truism is especially applicable when the behavior is multiply determined and serves many needs, as is the case with sexual behavior. Therefore each of these approaches should be seen as one part of a comprehensive HIV prevention program. Such efforts need to target individuals, small groups, communities, schools, and social policies. Adoption of theoretically guided and empirically validated approaches promise the most success.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Physiological-model-based derivation of the adult and child pharmacokinetic intraspecies uncertainty factors for volatile organic compounds.

The intraspecies uncertainty factor (UF(HH)=10x) is used in the determination of the reference dose or reference concentration and accounts for the pharmacokinetic and pharmacodynamic heterogeneity within the human population. The Food Quality Protection Act of 1996 mandated the use of an additional uncertainty factor (UF(HC)=10x) to take into account potential pre- and postnatal toxicity and lack of completeness of the data with respect to exposure and toxicity to children. There is no conclusive experimental or theoretical justification to support or refute the magnitude of the UF(HH) and UF(HC) nor any conclusive evidence to suggest that a factor of 100 is needed to account for intrahuman variability. This study presents a new chemical-specific method for estimating the pharmacokinetic (PK) component of the interspecies uncertainty factor (UF(HH-PK) and UF(HC-PK)) for volatile organic compounds (VOCs). The approach utilizes validated physiological-based pharmacokinetic (PBPK) models and simplified physiological-model-based algebraic equations to translate ambient exposure concentration to tissue dose in adults and children the ratio of which is the UF(HH-PK) and UF(HC-PK). The results suggest that: (i) the UF(HH-PK) and UF(HC-PK) are chemical specific; (ii) for the chemicals used in this study there is no significant difference between UF(HH-PK) and UF(HC-PK); (iii) the magnitude of UF(HH-PK) and UF(HC-PK) varies between 0.033 and 2.85 with respect to tissue and blood concentrations; (iv) the body weight, the rate of ventilation, the fraction of cardiac output flowing to the liver, the blood : air partition coefficient, and the hepatic extraction ratio are the only parameters that play a critical role in the variability of tissue and blood doses within species; and (v) the magnitude of the UF(HH-PK) and UF(HC-PK) obtained with the simplified steady-state equations is essentially the same with that obtained with PBPK models. Overall, this study suggests that no adult-children differences in the parent chemical concentrations of the VOCs are likely to be observed during inhalation exposures. The physiological-model-based approaches used in the present study to estimate the UF(HH-PK) and UF(HC-PK) provide a scientific basis for their magnitude. They can replace the currently used empirical default approaches to provide chemical-specific UF(HH-PK) in future risk assessments.

Adolescent↗
PubMed1992

The allometric approach for interspecies scaling of pharmacokinetic parameters.

A long standing problem in pharmacokinetics and toxicology is the extrapolation and correlation between results obtained in different animal species and man. Animal data may be scaled-up to predict PPs in man using the allometric approach. The allometric approach is empirical, but easy, and is based on the fact that the underlying physiological processes such as blood flow, heartbeat duration, breath duration etc. are essentially physical and related to B. This approach is generally applicable to compounds that are essentially renally excreted. For substances that are highly extracted by the liver, Cltot is a function of the LBF among various species. Based on the concept of neoteny, use of brain weight affords a more correct approach to the scaling of Cl(int) of low extraction ratio drugs. By using the invariant pharmacokinetic time, the superficial differences in concentration-time profiles due to chronological time among different species are removed. Finally, as Boxenbaum (1984) has said "parameters to be scaled, independent variables, and the mathematical relationships used in the scaling process are all at the discretion of the investigator. There are no proper or improper approaches; the only limitations are those imposed by the investigator."

Animals↗
PubMed1995

[The ego/self experience of schizophrenic patients].

The self experience of schizophrenics (i.e. their ego-pathology) is conceptualized in a theoretical model of five basic dimensions of ego consciousness (identity, activity, demarcation, consistence/coherence, vitality). A systematic empirical study uses the Ego-pathology-Inventory (with 53 items, Interraterreliability Kappa 0.9, Retestreliability 0.65). The study population consists of 552 schizophrenics, 25 borderline personality disorders, 87 depressive disorders. Ego-pathology clearly differs the three diagnostic groups. Confirmatory factorial analysis allows to accept the theoretical model. Various external measurements correlate with ego pathology. Three empirical syndromes resulted from statistical search for data-structures. A series of arguments for validation of the concept allow the conclusion the the proposed ego pathology concept is a viable approach for empirically studying the experimental core of the schizophrenias.

Borderline Personality Disorder↗
PubMed2004

Empirical parametrization of pK values for carboxylic acids in proteins using a genetic algorithm.

Considerable effort has been devoted to the development of theoretical electrostatic methods to predict the pK values of ionizable residues in proteins. However, predictions appear often to be still at the qualitative or semi-quantitative level. We believe that, with the increasing number experimentally available pK values for proteins of known structure, an alternative approach becomes feasible: the empirical parametrization of the experimental protein pK database. Of course, in the long term, this empirical approach is no substitute for rigorous electrostatic analysis but, in the short term, it may prove to have useful predictive power and it may help to pinpoint the main structural determinants of pK values in proteins. Here we demonstrate the feasibility of the parametrization approach by fitting (using a genetic algorithm as fitting tool) the database for carboxylic acid pK values in proteins on the basis of an empirical equation that takes into account the two following kinds of effects: (1) long-range charge-charge interactions; (2) interactions of the given carboxylic acid group with its environment in the protein, which are described in terms of contributions from the different kind of atoms present in the protein (atomic contributions).

Algorithms↗
PubMed2004

Using hierarchical modeling in genetic association studies with multiple markers: application to a case-control study of bladder cancer.

BACKGROUND: Genetic association studies are generating much information, usually in the form of single nucleotide polymorphisms in candidate genes. Analyzing such data is challenging, and raises issues of multiple comparisons and potential false-positive associations. Using data from a case-control study of bladder cancer, we showed how to use hierarchical modeling in genetic epidemiologic studies with multiple markers to control overestimation of effects and potential false-positive associations. METHODS: The data were first analyzed with the conventional approach of estimating each main effect individually. We subsequently employed hierarchical modeling by adding a second stage (prior) model that incorporated information on the potential function of the genes. We used an empirical-Bayes approach, estimating the residual effects of the genes from the data. When the residual effect was set to zero, we instead used a semi-Bayes approach, in which they were pre-specified. We also explored the impact of using different second-stage design matrices. Finally, we used two approaches for assessing gene-environment interactions. The first approach added product terms into the first-stage model. The second approach used three indicators for subjects exposed to gene-only, environment-only, and both genetic and environmental factors. RESULTS: By pre-specifying the prior second-stage covariates, the estimates were shrunk to the mean of each pathway. The conventional model detected a number of positive associations, which were reduced with the hierarchical model. For example, the odds ratio for myeloperoxidase (G/G, G/A) genotype changed from 3.17 [95% confidence interval (CI), 1.32-7.59] to 1.64 (95% CI, 0.81-3.34). A similar phenomenon was observed for the gene-environment interactions. The odds ratio for the gene-environment interaction between tobacco smoking and N-acetyltransferase 1 fast genotype was 2.74 (95% CI, 0.68-11.0) from the conventional analysis and 1.24 (95% CI, 0.80-1.93) from the hierarchical model. CONCLUSION: Adding a second-stage hierarchical modeling can reduce the likelihood of false positive via shrinkage toward the prior mean, improve the risk estimation by increasing the precision, and, therefore, represents an alternative to conventional methods for genetic association studies.

Arylamine N-Acetyltransferase↗
PubMed2005

A prognostic approach to defining chronic pain.

This paper develops a prognostic approach to defining chronic back pain. Possible and probable chronic back pain were defined, respectively, by a 50% and an 80% (or greater) probability of future clinically significant back pain. We assessed whether an empirically derived chronic pain classification satisfied these validating criteria among 1213 primary care back pain patients assessed at baseline and at 1, 2 and 5 year follow-ups. From multiple measures of back pain intensity and dysfunction, Latent Transition Regression Analysis empirically identified four pain severity latent classes: no pain; mild pain; moderate pain and limitation; and severe, limiting pain. From one observation point to the next, patients were most likely to remain in the same pain severity class, but chronic pain was better characterized as a dynamic state than a static trait. Among persons with severe, limiting pain, prognostic variables (depression, diffuse pain, pain persistence) improved prediction of future severe, limiting pain. A risk score developed from pain severity and prognostic measures identified risk levels corresponding to 50 and 80% probability thresholds for predicting future clinically significant back pain. At baseline and 1 year, 6.1 and 4.4% of study patients met or exceeded the 80% risk threshold for probable chronic back pain. An additional 20.3% at baseline and 12.5% at 1 year met or exceeded the 50% risk threshold for possible chronic back pain. Defining chronic pain prospectively, by risk thresholds for future clinically significant pain, provides an empirically grounded approach to chronic pain assessment.

Adolescent↗
PubMed1989

Neutropenia: antibiotic combinations for empiric therapy.

During the last two decades the mortality from gram-negative septicemia in neutropenia patients with serious underlying disease has declined from 85% to less than 20%. Many factors seem responsible for this trend: (a) the development of potent broad-spectrum antimicrobial agents (b) aggressive clinical approaches to empiric therapy entailing the use of antibiotics before results of cultures are known. (c) better supportive care, (d) improved treatment of underlying disease. Controversy persists about the choice of "optimum" regimens: clinical studies to date show major differences in evaluation criteria, particularly in the definition of "response". The largest and most convincing studies of gram-negative bacteremia still favor the use of antibiotic combinations in patients with profound, persistent neutropenia.

Agranulocytosis↗
PubMed2005

50 years of preclinical anticancer drug screening: empirical to target-driven approaches.

The number of anticancer agents that fail in the clinic far outweighs those considered effective, suggesting that the selection procedure for progression of molecules into the clinic requires improvement. The value of any preclinical model will ultimately depend on its ability to accurately predict clinical response. This review focuses on the major contributions of preclinical screening models to anticancer drug development over the past 50 years. Over time, a general transition has been observed from the empirical drug screening of cytotoxic agents against uncharacterized tumor models to the target-orientated drug screening of agents with defined mechanisms of action. New approaches to anticancer drug development involve the molecular characterization of models along with an appreciation of the pharmacodynamic and pharmacokinetic properties of compounds [e.g., the US National Cancer Institute (NCI) in vitro 60-cell line panel, hollow fiber assay, and s.c. xenograft]. Contributions of other potentially more clinically relevant in vivo tumor models including orthotopic, metastatic, and genetically engineered mouse models are also reviewed. Although this review concentrates on the preclinical screening efforts of the NCI, European efforts are not overlooked. Europe has played a key role in the development of new anticancer agents. The two largest academic drug development groups, the European Organisation for Research and Treatment of Cancer and Cancer Research UK, have been collaborating with the NCI in the acquisition and screening of compounds since the 1970s. As with the drug development process internationally, rational pharmacodynamic approaches have more recently been adopted by these two groups.

Animals↗
PubMed2001

Catalytic wet oxidation of phenol: kinetics of phenol uptake.

Catalytic phenol oxidation in aqueous phase under intermediate temperature and pressure has been carried out in order to determine the kinetic model of phenol uptake rate. The catalyst employed here was a commercial one based on copper supplied by Engelhard (Cu-0203T). Operational variables have been studied in the following ranges: temperature from 127 to 180 degrees C, oxygen pressure from 3.2 to 16 bar, initial phenol concentration from 680 to 1200 ppm, and catalyst concentration from 0 to 1550 g/L of liquid phase. Because of the wide interval here employed for the catalyst concentration, two experimental setups have been used: a basket stirred tank reactor (BSTR) with the liquid phase in batch and an integral fixed-bed reactor (FBR) with co-current upflow of gas and liquid phases. An important influence of the reaction in the bulk liquid was obtained in both types of reactor. This fact has been taken into account in the kinetic model according to different approaches. The first approach was a breakup of the reaction rate in two kinetic expressions, considering the homogeneous and heterogeneous contribution separately; the second approach was empirical where the reaction rate is a potential function of the catalyst concentration. It was found that the extent of reaction in the bulk liquid is also influenced by the catalyst concentration and that the first approach is not able to adequately predict the experimental results. Finally a kinetic model, based on the second approach, was discriminated, with a power law for the catalyst concentration with an order about 0.4. This model fits quite well the experimental data obtained in both experimental setups, BSTR and FBR, throughout the wide range of variables studied.

Catalysis↗
PubMed2001

The teaching of health care ethics to students of nursing in the UK: a pilot study.

Senior lecturers/lecturers in mental health nursing (11 in round one, nine in round two, and eight in the final round) participated in a three-round Delphi study into the teaching of health care ethics (HCE) to students of nursing. The participants were drawn from six (round one) and four (round three) UK universities. Information was gathered on the organization, methods used and content of HCE modules. Questionnaire responses were transcribed and the content analysed for patterns of interest and areas of convergence or divergence. Findings include: the majority (72.8%) of the sample believed that insufficient time was allocated to the teaching of HCE; case studies were considered a popular, although problematic, teaching method; the 'four principles' approach was less than dominant in the teaching of HCE; and virtue ethics was taught by only 36.4% of the participants. The Delphi technique proved adequate and worth while for the purposes of this study. Further empirical research could aim to replicate or contradict these findings, using a larger sample and recruiting more university departments. Reflection is required on several issues, including the depth and breadth to which ethics theory and, more controversially, meta-ethics, are taught to nursing students.

Adult↗
PubMed1994

Abstinence and neutrality: development and diverse views.

Usually, Freud adopted a technical device for personal or practical reasons and only later formulated its theoretical basis. His conception of abstinence initially seemed designed to curb his own troublesome erotic countertransference. These speculations, while having no bearing on the clinical value of abstinence and related neutrality, do emphasise the necessity to assess their utility objectively, on the basis of clinical data. Diverse views of abstinence and neutrality persist in part because early inconsistencies in Freud's conceptions remain unresolved, and in part because these views are derived from the analyst's personality and character, are not based upon clinical data, but are buttressed by iteration. An approach to empirical assessment is suggested using multiple analyst-observers: (1) to develop reliable criteria for four analyst behaviours: abstinence, neutrality, gratification and suggestion; and (2) to evaluate enhancement or impairment of analytic work. Utilisation of this approach in the supervision of candidates would enhance analytic pedagogy and to some degree facilitate a research orientation in candidates.

Character↗
PubMed1992

Neural networks in pharmacodynamic modeling. Is current modeling practice of complex kinetic systems at a dead end?

Neural networks (NN) are computational systems implemented in software or hardware that attempt to simulate the neurological processing abilities of biological systems, in particular the brain. Computational NN are classified as parallel distributed processing systems that for many tasks are recognized to have superior processing capability to the classical sequential Von Neuman computer model. NN are recognized mainly in terms of their adaptive learning and self-organization features and their nonlinear processing capability and are considered most suitable to deal with complex multivariate systems that are poorly understood and difficult to model by classical inductive, logically structured modeling techniques. A NN is applied to demonstrate one of the potentially many applications of NN for modeling complex kinetic systems. The NN was used to predict the effect of alfentanil on the heart rate resulting from a complex infusion scheme applied to six rabbits. Drug input-drug effect data resulting from a repeated, triple infusion rate scheme lasting from 30 to 180 min was used to train the NN to recognize and emulate the input-effect behavior of the system. With the NN memory fixed from the 30- to 180-min learning phase the NN was then tested for its ability to predict the effect resulting from a multiple infusion rate scheme applied in the subsequent 180 to 300 min of the experiment. The NN's ability to emulate the system (30-180 min) was excellent and its predictive extrapolation capability (180-300 min) was very good (mean relative prediction accuracy of 78%). The NN was best in predicting the higher intensity effect and was able to identify and predict an overshoot phenomenon likely caused by a withdrawal effect from acute tolerance. Current modeling philosophy and practice is discussed on the basis of the alternative offered by NN in the modeling of complex kinetic systems. In modeling such systems it is questioned whether traditional modeling practice that insists on structure relevance and conceptually pleasing structures has any practical advantages over the empirical NN approach that largely ignores structure relevance but concentrates on the emulation of the behavior of the kinetic system. The traditional searching for appropriate models of complex kinetic systems is a painstakingly slow process. In contrast, the search for empirical models using NN will continue to improve, limited only by technological advances supporting the very promising NN developments.

Alfentanil↗