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Biomedical subjects

K E Campbell

Publications and source records attributed to K E Campbell.

At least 19 recordsLinked to original sources
PubMed1998

In vitro patch-clamp studies in skin fibroblasts.

We have conducted single-channel patch-clamp experiments in skin fibroblasts maintained in culture. Two different cell lines, a mouse 3T3-L1 cell line and a human B17 cell line, were selected for these pilot studies. Recordings were made from both cell-attached and excised inside-out patches at room temperature. In the case of the 3T3-L1 cells, the success rate in obtaining good seals (> 1Gomega) was low, and channel openings in either cell-attached or excised patches were rare. We have, however, identified a channel in a cell-attached configuration with a slope conductance of 39 pS in symmetrical K+ solutions. In the case of the human B17 cells, good quality seals were more readily obtained. One principal type of channel opening was identified. In cell-attached patches, the prevalent type of channel in symmetrical K+ solutions had a conductance of 187 pS. This channel was activated by strong depolarization, and there was usually more than one active channel in the patch. It was blocked by extracellular tetraethylammonium (20 mM), and persisted when external Cl- was replaced by aspartate. In excised inside-out patches bathed in symmetrical K+, this channel was activated by an increase in Ca+ applied to the intracellular face. A large conductance channel (175 pS) was also observed in excised inside-out patches, with a reverse physiological K+ gradient. This channel had a reversal potential > 40 mV and appeared not to be voltage-dependent under these recording conditions (2 mM Ca(2+)i). We conclude that the channel we have identified in these cells belongs to the maxi-K+ channel class.

3T3 Cells↗
PubMed1998

Scalable methodologies for distributed development of logic-based convergent medical terminology.

As the size and complexity of medical terminologies increase, terminology modelers are increasingly hampered by lack of tools and methods to manage the development process. This paper presents our use and ongoing evaluation of a description-logic classifier to support cognitive scalability of the underlying terminology and our enhancements to that classifier to support concurrent development utilizing semantics-based concurrency control methods. Our enhancements, collectively referred to as the Gálapagos, consist of several applications that take locally-developed terminology enhancements from multiple sites, identify conflicting design decisions, support the modelers' reconciliation of the conflicting designs, and efficiently disseminate updates tailored for locally enhanced terminologies. We have tested our ideas through concurrent evolutionary enhancement of SNOMED International at three Kaiser Permanente regions and the Mayo Clinic. We have found that the underlying environment has met our design objectives, and supports semantic-based concurrency control, and identification and resolution of conflicting design decisions.

Artificial Intelligence↗
PubMed1998

Compositional concept representation using SNOMED: towards further convergence of clinical terminologies.

This paper describes several approaches to the expression and coding of clinical concepts as composites of elementary entities, and describes an approach based on SNOMED RT that may permit further convergence of clinical terminology efforts. We explain the shortcomings of previous approaches to compositional concept representation, as well as the reasons for SNOMED's current approach, which adopts a foundation based in description logics (DLs). The DL model has many advantages: it establishes a formal semantics for SNOMED assertions and suggests a syntax; it provides a basis for understanding expressiveness and computational complexity, through correspondence with known results from DLs; and it helps to clarify the relationships among existing concept representation methods in SNOMED, NHS Clinical Terms (formerly the Read Codes), and GALEN, making a path to convergence more clear.

Models, Theoretical↗
PubMed1998

A "lexically-suggested logical closure" metric for medical terminology maturity.

Medical Terminologies are becoming increasingly expressive secondary to their increase in size, and are becoming increasingly difficult to analyze secondary to inconsistencies in their use and complex interrelationships that are often not explicitly defined. To address these problems, SNOMED-RT is being developed to allow consistent use, and to define explicitly interrelationships between terms. Ensuring the quality of a terminology system like SNOMED-RT presents new challenges which we are trying to address with theoretically-grounded methodologies for quality management. Here we describe an initial metric toward achieving this goal called "lexically-suggested logical closure." We explain how this metric can be useful for tracking the maturity and quality of a terminology, and apply this metric to track the progress of SNOMED-RT development over a portion of its life-cycle.

Algorithms↗
PubMed1998

Reproducibility of interpreting "and" and "or" in terminology systems.

High quality terminologies are a fundamental requirement in a range of health care applications. To ensure high quality terminologies we should reflect about the understandability, reproducibility and utility criteria within a terminology. This paper describes efforts to improve the understandability of SNOMED. We describe the problem related to the grammatical conjunctions "and" and "or" and how we applied basic semantic rules defined by the SNOMED Editorial Board. The results show that the meaning of "and" and "or" in SNOMED can be made explicit in almost all cases and can be done in a reasonable, reliable, and reproducible manner.

Semantics↗
PubMed1998

Computer-facilitated collaboration: experiences building SNOMED-RT.

Collaborative development involving both individuals and groups is often less efficient than independent development because of communication overhead and integration costs. Despite the decreased development efficiency, collaborations promise more general-purpose products because of the opportunity for integration, with negotiation and reconciliation of diverse perspectives. Collaborations are also perhaps less costly when considered in contexts where there is significant duplication of effort. Computer-facilitated collaboration can reduce the communication and integration burden such that the increased effort required to manage a successful collaboration focuses primarily on the development of shared conceptual model among the developers by requiring that the work product be independently reproducible. This reproducibility requirement incorporates formal quality assurance processes into the development process. In this paper, we describe our initial experiences developing SNOMED-RT using such a computer-facilitated collaborative process. We quantify the extra costs incurred to achieve consistency in our efforts and reproducibility of our results.

Cooperative Behavior↗
PubMed1997

SNOMED RT: a reference terminology for health care.

We describe the framework for SNOMED RT (Reference Terminology), designed to complement the broad coverage of medical concepts in SNOMED with a set of enhanced features that significantly increases its value as a reference terminology for representing clinical data. We describe what is meant by a reference terminology, and differentiate SNOMED RT from specialized terminologies that enable user interfaces, electronic messaging, or natural language processing, as well as from other specialized reference terminologies whose primary purpose is for representing data that is not primarily clinical in nature. We then describe how SNOMED RT represents multiple hierarchies and incorporates description logic. We believe that such a comprehensive set of concepts at multiple levels of granularity, with multiple logic-based subsumption hierarchies can meet the requirements of a reference terminology for health care.

Terminology as Topic↗
PubMed1996

Gálapagos: computer-based support for evolution of a convergent medical terminology.

Current controlled medical terminologies fall short of the needs of informatics application developers. To overcome the limitations of current medical terminologies, many groups are independently enhancing existing terminologies to meet their local needs. With proper computer-based support, local enhancements can be used as evolutionary stepping stones toward a convergent medical terminology. Gálapagos is a collection of applications that can take local enhancements from multiple sites, identify conflicting design decisions, allow developers to reconcile the conflicting designs, and efficiently disseminate updates tailored specifically for compatibility with locally enhanced terminologies. This paper describes an initial proof-of-concept of the Gálapagos programs using data generated during concurrent SNOMED enhancement by Kaiser Permanente and the Mayo Clinic.

Medical Informatics Computing↗
PubMed1995

Development of a controlled medical terminology: knowledge acquisition and knowledge representation.

The creation of controlled medical terminologies is a central challenge in the development of electronic patient records. In the T-Helper patient-record system, designed for the care of patients with HIV disease, the IVORY module allows health-care workers to compose textual progress notes by making selections from menus generated automatically from a controlled medical terminology. Construction of this IVORY terminology required extensive design sessions with a team of computer scientists and an expert physician. Refinement of the terminology was only possible when the design team could envision how the completed T-Helper system would be used in the context of clinical practice. Development of controlled medical terminologies is a significant problem in knowledge acquisition. Techniques used to acquire and represent clinical concepts for the purpose of building decision-support systems also are appropriate for the construction of controlled terminologies such as the one in T-Helper.

Artificial Intelligence↗
PubMed1994

Variations in quantity-frequency measures of alcohol consumption from a general population survey.

This paper examines differences in quantity-frequency (QF) measures of alcohol consumption from the 1988 US National Health Interview Survey. Three methods--global QF, beverage-specific QF, and beverage-specific QF with drink size (QFS)--were used to estimate the average daily ethanol consumption (ADC) of current drinkers. These ADC estimates then were used to categorize drinkers into light, moderate or heavier drinking levels. Total prevalence estimates of heavier drinking were not significantly different among men, but were significantly higher with the QFS measure among women. All mean ADC scores were significantly different for both sexes. The global QF showed the lowest mean consumption, followed by the higher beverage-specific QF and QFS measures. Adding beverage type and drink size to the QF measures increased mean ADC scores for both men and women. However, moderately high correlations (0.84 for men and 0.88 for women) were found with ADC scores from the beverage-specific QF and QFS measures.

Alcohol Drinking↗
PubMed1994

Formal properties of the Metathesaurus.

The Metathesaurus is a machine-created, human edited and enhanced synthesis of authoritative biomedical terminologies. Its formal properties permit it to be a) exploited by computers, and b) modified and enhanced without compromising that usage. If further constraints were imposed on the existence and identity of Metathesaurus relationships, i.e., if every Metathesaurus concept had a "genus" and a "differentia," then the Metathesaurus could be converted into an "Aristotelian Hierarchy." In this sense, a genus is a concept that classifies another concept, and a differentia is a concept that distinguishes the classified concept from all other concepts in the same class. Since, in principle, these constraints would make the Metathesaurus easier to leverage and maintain computationally, it is interesting to ask to what degree the maintenance and enhancement procedures now in place are producing a Metathesaurus that is also an "Aristotelian Hierarchy." Given a liberal interpretation of the current Metathesaurus schema, the proportion of the Metathesaurus that is "Aristotelian" in each annual version is increasing in spite of dramatic concurrent increases in the number of Metathesaurus concepts. Without formality there is no modifiability nor scalability. [1] We need formal methods and computer-based tools that can help us with the task [of controlled medical vocabulary construction]. We need research in which controlled vocabulary development is the focus rather than a stepping stone for work on other theories and applications. [2]

Subject Headings↗
PubMed1993

A computer-based tool for generation of progress notes.

IVORY, a computer-based tool that uses clinical findings as the basic unit for composing progress notes, generates progress notes more efficiently than does a character-based word processor. IVORY's clinical findings are contained within a structured vocabulary that we developed to support generation of both prose progress notes and SNOMED III codes. Observational studies of physician participation in the development of IVORY's structured vocabulary have helped us to identify areas where changes are required before IVORY will be acceptable for routine clinical use.

Humans↗
PubMed1993

Representation of nursing terms for the description of patient problems using SNOMED III.

We conducted an experiment to determine if the terms recorded by nurses in the patient chart to describe patient problems could be represented using SNOMED III terms. The data sources for the patient problems were the nurses' progress notes and nursing care plans from 485 patient encounters in three diverse settings (NR02215). We entered the nursing terms into a relational database. We loaded the SNOMED III terms into a relational database and created a word index. We determined matches by identifying the English description of the SNOMED III term that best matched the term charted by the nurses. Sixty-nine percent of the nursing terms in the test subset were matched using one or more SNOMED III terms. We identified redundant SNOMED III terms for several nursing terms including fear and diarrhea. Our results suggest that terms recorded by nurses in the patient chart can be represented using SNOMED III terms. Further enhancement and refinement will improve the domain completeness of SNOMED III as a controlled healthcare vocabulary and decrease redundancies.

Humans↗
PubMed1992

Representation of clinical data using SNOMED III and conceptual graphs.

None of the coding schemes currently contained within the Unified Medical Language System (UMLS) is sufficiently expressive to represent medical progress notes adequately. Some coding schemes suffer from domain incompleteness, others suffer from the inability to represent modifiers and time references, and some suffer from both problems. The recently released version of the Systematized Nomenclature of Medicine (SNOMED III) is a potential solution to the data-representation problem because it is relatively domain complete, and because it uses a generative coding scheme that will allow the construction of codes that contain modifiers and time references. SNOMED III does have an important weakness, however. SNOMED III lacks a formalized system for using its codes; thus, it fails to ensure consistency in its use across different institutions. Application of conceptual-graph formalisms to SNOMED III can ensure such consistency of use. Conceptual-graph formalisms will also allow mapping of the resulting SNOMED III codes onto relational data models and onto other formal systems, such as first-order predicate calculus.

Medical Informatics Applications↗
PubMedDate not supplied

Terms used by nurses to describe patient problems: can SNOMED III represent nursing concepts in the patient record?

OBJECTIVE: To analyze the terms used by nurses in a variety of data sources and to test the feasibility of using SNOMED III to represent nursing terms. DESIGN: Prospective research design with manual matching of terms to the SNOMED III vocabulary. MEASUREMENTS: The terms used by nurses to describe patient problems during 485 episodes of care for 201 patients hospitalized for Pneumocystis carinii pneumonia were identified. Problems from four data sources (nurse interview, intershift report, nursing care plan, and nurse progress note/flowsheet) were classified based on the substantive area of the problem and on the terminology used to describe the problem. A test subset of the 25 most frequently used terms from the two written data sources (nursing care plan and nurse progress note/flowsheet) were manually matched to SNOMED III terms to test the feasibility of using that existing vocabulary to represent nursing terms. RESULTS: Nurses most frequently described patient problems as signs/symptoms in the verbal nurse interview and intershift report. In the written data sources, problems were recorded as North American Nursing Diagnosis Association (NANDA) terms and signs/symptoms with similar frequencies. Of the nursing terms in the test subset, 69% were represented using one or more SNOMED III terms.

Delivery of Health Care↗
PubMedDate not supplied

A logical foundation for representation of clinical data.

OBJECTIVE: A general framework for representation of clinical data that provides a declarative semantics of terms and that allows developers to define explicitly the relationships among both terms and combinations of terms. DESIGN: Use of conceptual graphs as a standard representation of logic and of an existing standardized vocabulary, the Systematized Nomenclature of Medicine (SNOMED International), for lexical elements. Concepts such as time, anatomy, and uncertainty must be modeled explicitly in a way that allows relation of these foundational concepts to surface-level clinical descriptions in a uniform manner. RESULTS: The proposed framework was used to model a simple radiology report, which included temporal references. CONCLUSION: Formal logic provides a framework for formalizing the representation of medical concepts. Actual implementations will be required to evaluate the practicality of this approach.

Computer Simulation↗