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PubMed1996

[Formulating problems of ecological diseases. Approaches to etiopathogenesis, classification and diagnosis of ecological diseases due to chemicals].

Our long-standing clinical trials proved nonspecific and stress factors contributing into environmental diseases. The studies helped to define traumatic variant of biologic stress, to describe its trigger mechanisms. The authors analyzed physiologic mechanisms of stress-related diseases, role of autonomous nervous system in formation of environmental diseases. Clinical classification of acute and chronic environmental diseases is given, with consideration of their diagnosis.

Adaptation, Physiological↗
PubMed1992

Formulation and (bio)availability problems of drug formulations in birds.

Most drugs used for the treatment of birds are not formulated for birds. Therefore the availability of drugs for birds and their administration routes largely depend on formulations available for man, mammals and to some extent poultry. The problems with the application of existing formulations, the drug concentrations and the many different avian species are discussed. The desire of the avian veterinarian for the combination of several active compounds presents special problems. This again requires extra data on the interactions in galenic, pharmaceutic, pharmacokinetic and dynamic phases, which are generally not readily available.

Animal Feed↗
PubMed1993

Problems in formulating method-insensitive proficiency testing materials.

Significant problems exist in formulating method-insensitive proficiency materials. Many steps are required in processing human plasma, and difficult choices are involved in the selection of appropriate materials to be added to the processed plasma. Additionally, analytes may vary widely in their recovery from method to method. To enhance understanding of the procedures and problems involved in the development and manufacture of proficiency materials, a number of constituents and their method-specific recoveries are reviewed.

Bias↗
PubMed1992

Interpersonal psychotherapy of depressed HIV-positive outpatients.

In an open pilot study, 23 depressed adults infected with human immunodeficiency virus were treated using interpersonal therapy. Twenty subjects recovered from depression after a mean of 16 sessions. The authors discuss six aspects of interpersonal therapy that make it useful with depressed HIV-infected persons: psychoeducation about the sick role; a here-and-now framework; formulation of problems from an interpersonal perspective; exploration of options for changing dysfunctional behavior patterns; identification of focused interpersonal problem areas (grief, role transition, interpersonal disputes, and interpersonal deficits); and the confidence therapists gain from a systematic approach to problem formulation and treatment. Results suggest that mental health professionals should consider interpersonal therapy as a treatment for depressed HIV-positive patients.

AIDS-Related Opportunistic Infections↗
PubMed2001

Defining populations: a key step in identifying spatial and temporal scales.

The scale at which ecological risk assessors frame their analyses can be driven by a number of considerations. In many cases, the selection of the scale is among the most important decisions within the 'problem-formulation' phase of the ecological risk characterization. The scale of a risk characterization is often defined based on ownership boundaries, ecological, or habitat boundaries and/or physical and hydrogeological boundaries (e.g., watersheds). With increasing value being placed on consideration of spatial scales in risk characterization, the need to define a scale that balances analytical and ecological realities is imperative. Defining the spatial scale based on the scale of a population offers the risk assessor the opportunity to improve the ecological relevance of the risk characterization. Arriving at a single operational definition of a population would be difficult and not appropriate because of the variability in sites, issues, and management goals; however, we can begin to review operational definitions and establish analytical frameworks by which to select the appropriate, site-specific scale within the problem-formulation phase. Defining a scale based on a combination of ecological and site ownership considerations and the inclusion of habitat quality in the assessment of scale can improve the power and relevance of the problem formulation and risk characterization. In this analysis, we assess methods for incorporating spatial considerations into risk analyses, beginning with developing an understanding of the context of a site within the larger landscape. Clearly defining the scale of an assessment including the operational definition of populations is an important step in the problem formulation. Within a site or landscape, the scale may be refined further based on the percentage of the land within the scale of the analysis that provides habitat for a given species.

Animals↗
PubMed2003

Patient-practitioner agreement: does it matter?

BACKGROUND: Good communication is a crucial clinical skill. Previous research demonstrated better clinical outcomes when practitioners and patients agree about the nature of patients' core presenting complaints. We investigated the nature of this agreement and its impact on outcome among depressed primary care patients. METHOD: We compared presenting problem formulations completed by patients, GPs and therapists in a primary care randomized controlled trial of cognitive-behavioural therapy and non-directive counselling for depression. Participants compiled formulations from a list of 13 potential problems of self-completed questionnaires. Subjects scored at least 14 on the Beck Depression Inventory (BDI) at baseline. Outcome measure for this study included BDI at 4 and 12 months, failure to attend for therapy when referred, dropout from therapy and patient satisfaction. RESULTS: Among 464 trial patients, 395 received therapy. Patient baseline problem formulations included significantly more items than GPs, who identified significantly more items than therapists. Agreement levels varied according to a range of patient and professional variables. While patients in complete agreement with their therapists about their main problem after assessment had lower average BDI scores at 12 months (9.7 v. 12.8, P=0.03); we found no other significant associations between the extent of agreement and clinical outcome. There were significant (but relatively weak) associations between agreement and aspects of patient satisfaction. CONCLUSION: Our results suggest that detailed mutual understanding of the presenting complaints may be less important than agreement that the core problem is psychological, and that referral for psychological therapy is appropriate.

Adolescent↗
PubMed1980

Primary care multidimensional model: a framework for formulating health problems in a primary care setting.

There is a need to develop a systematic method for integrating organic, emotional, personal, and environmental data of a patient's lifestyle into the management of health problems. The Primary Care Multidimensional Model (PCMM) was developed to assist in the formulation of an individual's health problem, whether categorized as biological, psychological or social. The PCMM was applied to 276 health problems attended in a consecutive sample of 84 adult patients cared for in an inner city primary care setting. Seventy-five percent of the problems were categorized as primarily biological, 14% as psychological, and 9% as social. Sixty-seven percent of the "biological" problems were found to have emotional, personal, or environmental variables from the patient's lifestyle considered relevant at the time of the study visit. All psychological and social problems were likewise multidimensional. In the population studied, over 75% of the health problems attended in a primary care practice fulfilled the biopsychosocial model of illness as defined by the PCMM. The heuristic value of this study is discussed.

Adaptation, Psychological↗
PubMed1992

Electrical impedance tomography using induced and injected currents.

A two-dimensional forward problem formulation is introduced for electrical impedance tomography (EIT) using induced currents. The forward problem is linearised around a certain resistivity distribution and the inverse problem is formulated as a solution of a linear system of equations. Sensitivity of boundary measurements to resistivity variations are analysed for spatially uniform, linear and quadratic fields. The formulation, however, is suitable for studying the effects of a general magnetic field applied to induce the currents in the conductive object. A similar inverse problem formulation is also developed for EIT using injected currents. Simulation studies are performed by reconstructing images of a simulation distribution using both methods separately with generalised inversion. It is also shown that the derived formulations for the inverse problems of the two methods can be combined to solve a larger set of equations with a greater number of independent measurements.

Electric Conductivity↗
PubMed2003

Evolutionary algorithms for the selection of single nucleotide polymorphisms.

BACKGROUND: Large databases of single nucleotide polymorphisms (SNPs) are available for use in genomics studies. Typically, investigators must choose a subset of SNPs from these databases to employ in their studies. The choice of subset is influenced by many factors, including estimated or known reliability of the SNP, biochemical factors, intellectual property, cost, and effectiveness of the subset for mapping genes or identifying disease loci. We present an evolutionary algorithm for multiobjective SNP selection. RESULTS: We implemented a modified version of the Strength-Pareto Evolutionary Algorithm (SPEA2) in Java. Our implementation, Multiobjective Analyzer for Genetic Marker Acquisition (MAGMA), approximates the set of optimal trade-off solutions for large problems in minutes. This set is very useful for the design of large studies, including those oriented towards disease identification, genetic mapping, population studies, and haplotype-block elucidation. CONCLUSION: Evolutionary algorithms are particularly suited for optimization problems that involve multiple objectives and a complex search space on which exact methods such as exhaustive enumeration cannot be applied. They provide flexibility with respect to the problem formulation if a problem description evolves or changes. Results are produced as a trade-off front, allowing the user to make informed decisions when prioritizing factors. MAGMA is open source and available at http://snp-magma.sourceforge.net. Evolutionary algorithms are well suited for many other applications in genomics.

Algorithms↗
PubMed2000

Integrating human health and ecological concerns in risk assessments.

The interconnections between ecosystems, human health and welfare have been increasingly recognized by the US government, academia, and the public. This paper continues this theme by addressing the use of risk assessment to integrate people into a single assessment. In a broad overview of the risk assessment process we stress the need to build a conceptual model of the whole system including multiple species (humans and other ecological entities), stressors, and cumulative effects. We also propose converging landscape ecology and evaluation of ecosystem services with risk assessment to address these cumulative responses. We first look at how this integration can occur within the problem formulation step in risk assessment where the system is defined, a conceptual model created, a subset of components and functions selected, and the analytical framework decided in a context that includes the management decisions. A variety of examples of problem formulations (salmon, wild insects, hyporheic ecosystems, ultraviolet (UV) radiation, nitrogen fertilization, toxic chemicals, and oil spills) are presented to illustrate how treating humans as components of the landscape can add value to risk assessments. We conclude that the risk assessment process should help address the urgent needs of society in proportion to importance, to provide a format to communicate knowledge and understanding, and to inform policy and management decisions.

Animals↗
PubMed2002

Improved Monte Carlo sampling in a real space approach to the crystallographic phase problem.

A real space approach has been proposed to solve the x-ray phase problem formulated as a minimization problem. The cost function consists of two parts: one represents the usual crystallographical residual while the other enforces the probability distribution of the invariant phase triplets. Starting from a random real space structure, the atoms are moved one by one to gradually reduce the cost function (simulated annealing). In addition, the atoms are encouragd to preferentially sample the high density regions in space determined by an approximate density map which in turn is updated and modified by averaging and Fourier synthesis. Such a reduction of the configurational space has led to considerable improvement of the algorithm compared to an earlier version. Trial calculations for structures including hexadecaisoleucinomycin (HEXIL) and a collagenlike peptide (PPG) are presented.

Journal Article↗
PubMed2000

A hybrid minimal principle for the crystallographic phase problem.

Simulated annealing is used to solve the X-ray phase problem formulated as a minimization problem. The cost function consists of two parts, one represents the discrepancy between measured and calculated intensities while the other monitors the probability distribution of the triplets. From a random real-space structure at the start, the atoms are moved one by one to gradually reduce the cost function until the best structure emerges. Trial calculations for structures including hexadecaisoleucinomycin (HEXIL) are presented. Comparison of this method with other related methods is made.

Crystallography, X-Ray↗