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Biomedical subjects

R A Rocha

Publications and source records attributed to R A Rocha.

15 recordsLinked to original sources
PubMed2006

Modeling end-users' acceptance of a knowledge authoring tool.

OBJECTIVES: Knowledge bases comprise a vital component in the classic medical expert system model, yet the knowledge acquisition process by which they are created has been characterized as highly iterative and labor-intensive. The difficulty of this process underscores the importance of knowledge authoring tools that satisfy the demands of end-users. The authors hypothesize that the acceptability of a knowledge authoring tool for the creation of medical knowledge base content can be predicted by an accepted model in the information technology (IT) field, specifically the Technology Acceptance Model (TAM). METHODS: An online survey was conducted amongst knowledge base authors who had previously established experience with the authoring tool software. The Likert-based questions in the survey were patterned directly after accepted TAM constructs with minor modifications to particularize them to the software being used. The results were analyzed using structural equation modeling. RESULTS: The TAM performed well in predicting endusers' behavioral intentions to use the knowledge authoring tool. Five out of seven goodness-of-fit statistics indicate that the model represents the behavioral intentions of the authors well. All but one of the hypothesized relationships specified by the TAM were significant with p values less than 0.05. CONCLUSIONS: The TAM provides an adequate means by which development teams can anticipate and better understand what aspects of a knowledge authoring tool are most important to their target audience. Further research involving other behavioral models and an expanded user base will be necessary to better understand the scope of issues that factor into acceptability.

Attitude↗
PubMed2005

Influence of dietary protein supply on resistance to experimental infections with Haemonchus contortus in Ile de France and Santa Ines lambs.

The effect of Haemonchus contortus infection in sheep fed with a moderate and high protein content diet was evaluated in two breeds of sheep. Forty-eight Ile de France and Santa Ines lambs were maintained indoors since birth, in worm-free conditions. The lambs were allocated after weaning in four groups of six animals per breed, which were either infected or remain uninfected and given access to either a moderately or highly metabolizable protein diet. The moderately and highly metabolizable protein diets were calculated to supply 75 and 129 g metabolizable protein per kg of dry matter (MP/kg DM), respectively. The infection consisted of a trickle infection with 300 infective larvae, three times a week, for 12 weeks. Significant differences were observed for mast cell, globule leukocyte and eosinophil counts in the abomasal mucosa of the infected groups compared to the control of both breeds (P<0.05), regardless of the diet supplied. Significantly higher IgA anti-L5 antibody was detected in the infected Santa Ines groups than in the infected Ile de France groups (P<0.05). Increased metabolizable protein supply resulted in larger body weight gain and higher packed cell volumes for both breeds (P<0.05). Both breeds showed an increased ability to withstand the pathophysiological effects of H. contortus infection when given access to the highly metabolizable protein diet. However, increased metabolizable protein supply resulted in reduced worm burdens in Santa Ines lambs but not in the Ile de France lambs (P<0.05). The present results show that the increase in protein content in growing lamb diets may benefit resistance and resilience to gastrointestinal parasites but that these benefits may vary among breeds.

Abomasum↗
PubMed2004

Resistance of Santa Ines, Suffolk and Ile de France sheep to naturally acquired gastrointestinal nematode infections.

A study was conducted to assess the breed resistance against nematode infections in Santa Ines, Ile de France and Suffolk male lambs over a 9-month period in São Paulo state, Brazil. Lambs were born during the winter (year 2000) and were weaned at 2 months of age. The animals were then housed and treated with anthelmintics to eliminate natural infections by gastrointestinal nematodes. In late October 2000, lambs were placed in a paddock, where they stayed until August of the following year. Fecal and blood samples were taken from each animal every 2 weeks. On the same day, a pasture sample was collected to determine the number of infective larvae on the herbage. To prevent deaths, individual treatment with anthelmintics was provided to lambs with fecal egg counts (FEC) higher than 4000 eggs per gram (EPG) or with a packed cell volume (PCV) lower than 21%. In August 2001, all animals were slaughtered and the worms present in samples of the gastrointestinal contents were identified and counted. Most of the Suffolk and Ile de France sheep received three to six anthelmintic treatments over a period of 7 months, while most of the Santa Ines were not treated. Reductions in PCV and plasma protein values associated with high FEC and worm burdens were recorded, particularly, in Suffolk and Ile de France lambs. Haemonchus contortus and Oesophagostomum columbianum burdens and number of nodular lesions caused in the large intestine by O. columbianum larvae were significantly lower in Santa Ines sheep. All three breeds showed similar Trichostrongylus colubriformis worm burdens. The relative resistance of Santa Ines young male sheep was superior to that of Suffolk and Ile de France sheep.

Abomasum↗
PubMed2001

Development of a template model to represent the information content of chest radiology reports.

The authors describe the application of a methodology for developing representational models for loosely structured medical domains. The methodology is subdivided in two interrelated tasks: terminology acquisition and template generation. The methodology is applied to the domain of chest radiology, producing a domain-specific lexicon and a series of templates to represent all the relevant clinical information stated on a chest x-ray report. Details about the successive application of the methodology and the resulting versions of the lexicon and templates are presented. The most relevant aspects of the methodology utilization are discussed and compared with evidence from other authors.

Humans↗
PubMed1998

Linking a medical vocabulary to a clinical data model using Abstract Syntax Notation 1.

We have created a clinical data model using Abstract Syntax Notation 1 (ASN. 1). The clinical model is constructed from a small number of simple data types that are built into data structures of progressively greater complexity. Important intermediate types include Attributes, Observations, and Events. The highest level elements in the model are messages that are used for inter-process communication within a clinical information system. Vocabulary is incorporated into the model using BaseCoded, a primitive data type that allows vocabulary concepts and semantic relationships to be referenced using standard ASN. 1 notation. ASN. 1 subtyping language was useful in preventing unbounded proliferation of object classes in the model, and in general, ASN.1 was found to be a flexible and robust notation for representing a model of clinical information.

Artificial Intelligence↗
PubMed1998

Evaluation of a semantic data model for chest radiology: application of a new methodology.

An essential step toward the effective processing of the medical language is the development of representational models that formalize the language semantics. These models, also known as semantic data models, help to unlock the meaning of descriptive expressions, making them accessible to computer systems. The present study tries to determine the quality of a semantic data model created to encode chest radiology findings. The evaluation methodology relied on the ability of physicians to extract information from textual and encoded representations of chest X-ray reports, whilst answering questions associated with each report. The evaluation demonstrated that the encoded reports seemed to have the same information content of the original textual reports. The methodology generated useful data regarding the quality of the data model, demonstrating that certain segments were creating ambiguous representations and that some details were not being represented.

Adult↗
PubMed1996

Coupling vocabularies and data structures: lessons from LOINC.

Using LOINC's data model for laboratory test result names as a starting point, an extended model is presented, coupled to a more complete vocabulary model. Justifications for this approach are obtained from a matching experiment that attempts to identify SNOMED terms that correspond to the various components of the LOINC names. Some limitations of LOINC's current vocabulary model, exposed during the matching process, are discussed.

Classification↗
PubMed1994

Designing a controlled medical vocabulary server: the VOSER project.

The authors describe their experience designing a controlled medical vocabulary server created to support the exchange of patient data and medical decision logic. The first section introduces practical and theoretical premises that guided the design of the vocabulary server. The second section describes a series of structures needed to implement the proposed server, emphasizing their conformance to the design premises. The third section introduces potential applications that provide services to end users and also a group of tools necessary for maintaining the server corpus. In the fourth section, the authors propose an implementation strategy based on a common framework and on the participation of groups from different health-related domains.

Clinical Laboratory Information Systems↗
PubMed1994

Using digrams to map controlled medical vocabularies.

A program for matching between controlled medical vocabularies has been developed which adopts methods used in the domain of Information Retrieval. This program combines a stemmer based on fragments of words (digrams) with a similarity function. The proposed stemmer did not require any knowledge about word-formation rules and helped the identification of several kinds of word variants. The adopted similarity function assigned the highest score to the best candidate match in 99.0% of the cases.

Algorithms↗
PubMed1993

Automated translation between medical vocabularies using a frame-based interlingua.

The integration of clinical systems almost always requires a translation phase, where vocabularies are compared and the similar concepts are matched. The lack of standards in the area of medical concept representation makes this task very difficult. The authors describe the development of a frame-based application that automatically translates terms found in one vocabulary to another. The application implements an innovative scoring algorithm that ranks the best matches using an exponential scale. Preliminary results and the comparison against a manual process in the same domain are also discussed.

Electronic Data Processing↗
PubMed1979

Nifurtimox in the treatment of South American leishmaniasis.

A trial of Nifurtimox (Lampit) in 26 patients with mucocutaneous leishmaniasis is reported. 13 patients with cutaneous lesions and 13 patients with mucosal disease were treated with a daily oral divided dose of 10 mg/kg body-weight for 30 days. 46% of the cutaneous cases and only 15% of the mucosal cases apparently responded to this regimen during at least one year of follow up. The difficulties of assessing cure in this disease are briefly discussed. We consider that Nifurtimox remains an investigational drug. While possibly exhibiting some anti-leishmanial activity it cannot be recommended for routine use in either form of the disease.

Adolescent↗
PubMedDate not supplied

An event model of medical information representation.

OBJECTIVE: Develop a model for structured and encoded representation of medical information that supports human review, decision support applications, ad hoc queries, statistical analysis, and natural-language processing. DESIGN: A medical information representation model was developed from manual and semiautomated analysis of patient data. The key assumption of the model is that medical information can be represented as a series of linked events. The event representation has two main components. The first component is a frame or template definition that specifies the attributes of the event. The second component is a structured vocabulary, the terms of which are taken as the values of the slots in the event template structure. Individual event instances are linked by specific named relationships. RESULTS: The proposed model was used to represent a chest-radiograph report. CONCLUSIONS: The event model of medical information representation provides a mechanism for formal definition of the logical structure of medical data and allows explicit time-oriented and associative relationships between event instances.

Computer Simulation↗
PubMedDate not supplied

Evaluation of a "lexically assign, logically refine" strategy for semi-automated integration of overlapping terminologies.

OBJECTIVE: To evaluate a "lexically assign, logically refine" (LALR) strategy for merging overlapping healthcare terminologies. This strategy combines description logic classification with lexical techniques that propose initial term definitions. The lexically suggested initial definitions are manually refined by domain experts to yield description logic definitions for each term in the overlapping terminologies of interest. Logic-based techniques are then used to merge defined terms. METHODS: A LALR strategy was applied to 7,763 LOINC and 2,050 SNOMED procedure terms using a common set of defining relationships taken from the LOINC data model. Candidate value restrictions were derived by lexically comparing the procedure's name with other terms contained in the reference SNOMED topography, living organism, function, and chemical axes. These candidate restrictions were reviewed by a domain expert, transformed into terminologic definitions for each of the terms, and then algorithmically classified. RESULTS: The authors successfully defined 5,724 (73%) LOINC and 1,151 (56%) SNOMED procedure terms using a LALR strategy. Algorithmic classification of the defined concepts resulted in an organization mirroring that of the reference hierarchies. The classification techniques appropriately placed more detailed LOINC terms underneath the corresponding SNOMED terms, thus forming a complementary relationship between the LOINC and SNOMED terms. DISCUSSION: LALR is a successful strategy for merging overlapping terminologies in a test case where both terminologies can be defined using the same defining relationships, and where value restrictions can be drawn from a single reference hierarchy. Those concepts not having lexically suggested value restrictions frequently indicate gaps in the reference hierarchy.

Algorithms↗
PubMedDate not supplied

Development of the Logical Observation Identifier Names and Codes (LOINC) vocabulary.

The LOINC (Logical Observation Identifier Names and Codes) vocabulary is a set of more than 10,000 names and codes developed for use as observation identifiers in standardized messages exchanged between clinical computer systems. The goal of the study was to create universal names and codes for clinical observations that could be used by all clinical information systems. The LOINC names are structured to facilitate rapid matching, either automated or manual, between local vocabularies and the universal LOINC codes. If LOINC codes are used in clinical messages, each system participating in data exchange needs to match its local vocabulary to the standard vocabulary only once. This will reduce both the time and cost of implementing standardized interfaces. The history of the development of the LOINC vocabulary and the methodology used in its creation are described.

Classification↗