PubMed Health⌕ Search

Biomedical subjects

S M Powsner

Publications and source records attributed to S M Powsner.

11 recordsLinked to original sources
PubMed1992

Prototyping an institutional IAIMS/UMLS information environment for an academic medical center.

The paper describes a prototype information environment designed to link network-based information resources in an integrated fashion and thus enhance the information capabilities of an academic medical center. The prototype was implemented on a single Macintosh computer to permit exploration of the overall "information architecture" and to demonstrate the various desired capabilities prior to full-scale network-based implementation. At the heart of the prototype are two components: a diverse set of information resources available over an institutional computer network and an information sources map designed to assist users in finding and accessing information resources relevant to their needs. The paper describes these and other components of the prototype and presents a scenario illustrating its use. The prototype illustrates the link between the goals of two National Library of Medicine initiatives, the Integrated Academic Information Management System (IAIMS) and the Unified Medical Language System (UMLS).

Academic Medical Centers↗
PubMed1992

Automated online transition from the medical record to the psychiatric literature.

Psych Topix is a knowledge-based program which guides the clinician from an on-line clinical report to a search of the psychiatric literature or of other relevant databases. It provides this guidance by using an outline of key topics in a clinical field to provide "concept-based" links. Each topic is augmented with an activation expression to signal when that topic is potentially relevant to a case, and with database search expressions to allow focused retrieval of information. The bibliographic retrieval component of Psych Topix is currently operational as part of the daily, routine operation of a psychiatric consultation service. The system is also implemented in a demonstration mode to provide retrieval from three additional textual databases. The current Psych Topix system provides a working demonstration of the clinical feasibility of using concept-based links to facilitate the focused, automated transition between on-line medical databases.

Expert Systems↗
PubMed1991

From patient reports to bibliographic retrieval: a Meta-1 front-end.

A software front-end has been programmed to help construct Medline query expressions from selected text in clinical records. The user "clicks" to choose pertinent words or phrases from the text with a pointing device and the words are translated into Medical Subject Headings (MeSH). The National Library of Medicine's Unified Medical Language System Meta-1 Thesaurus is used to look up the words selected by the user. The software traces through chains of synonyms to assemble a small set of MeSH indexing terms. The user then makes the final selection from among the MeSH terms and combines chosen terms using logical connectives to form a Medline query which is passed on to Grateful Med. This approach provides the clinical user with a natural starting point, the text of a patient report with no need to know the MeSH terminology. The software handles the translation that otherwise would necessitate looking up terms in MeSH guidebooks, as well as handling the added drudgery of checking out different synonyms. Preliminary evaluation of this approach with clinical trainees indicated that they find the front-end a straightforward way to search for literature relevant to a clinical case. Having a tool for immediate translation from clinical terminology to indexing terminology seems to be an important factor. Apparently minor issues in interface design, such as keeping the clinical report displayed simultaneously along with the search under construction, and keeping both visible during the search itself seem to help orient the user.

Grateful Med↗
PubMed1989

Automated bibliographic retrieval based on current topics in hepatology: hepatopix.

The Hepatopix computer program helps the physician go from a computerized clinical record directly to a computerized search of the medical literature. The program uses a hierarchical list of current (key) topics in hepatology to offer "intelligent" searches. Each topic has associated "selection logic" and a tested Medline search. Starting with a liver biopsy case record, Hepatopix evaluates the selection logic to determine which topics may be pertinent to the case (based on clinical findings, lab tests, and critical words or phrases in the summary). The physician then picks those topics which are interesting enough to warrant a literature search. The citations are retrieved using search strategies stored for each topic and presented. Hepatopix is operational with over 200 topics in the realm of liver neoplasms, operating on liver biopsy case summaries from the Klatskin Database of Liver Biopsies. Besides demonstrating clinical case-directed bibliographic retrieval, it demonstrates the utility of a "key topics" list as a bridge between medical databases.

Bibliography of Medicine↗
PubMed1988

Semantic relationships and medical bibliographic retrieval: a preliminary assessment.

This paper describes a project exploring whether semantic relationships between bibliographic terms may effectively partition the clinical literature. To address this question, a set of semantic relationships was identified between pairs of bibliographic terms taken from four categories: (1) diseases, (2) treatments, (3) tests, and (4) patient characteristics. The MEDLINE system of the National Library of Medicine was used to generate lists of abstracts relating to pairs of clinical terms. Each list of abstracts was examined to identify the semantic relationships, if any, which applied to the two terms in each paper. The study suggests that semantic relationships may play a potentially valuable role in assisting computer-based medical bibliographic retrieval. The degree to which relationships partition the literature is strongly dependent on the underlying semantics of the particular bibliographic terms involved.

Information Systems↗
PubMed1988

Semantically assisted medical bibliographic retrieval: an experimental computer system.

An experimental computer-based bibliographic retrieval system has been implemented to explore how semantic (conceptual) relationships between MeSH terms might assist the retrieval process. To construct the experimental system's database, lists of abstracts were produced using MEDLINE. Each list contained papers discussing a specified pair of terms. Each abstract was then analyzed to determine the specific relationship(s) between the two terms discussed in that paper. The project then explored how these semantic relationships could be incorporated into the computer to enhance bibliographic retrieval.

Information Systems↗
PubMed1987

Contrast ultrasonography of the kidney: a new method for evaluation of renal perfusion in vivo.

Assessment of the effects of pharmacologic agents on renal blood flow (RBF) is clinically important in many disease states, including hypertension and congestive heart failure. However, because of the complexities of RBF, quantitation in vivo has been technically difficult. This study demonstrates the utility of ultrasound imaging of the kidney combined with injection of a sonicated radiocontrast solution (Renografin-76) for the assessment of regional renal blood flow. The technique uses a suspension of uniform microbubbles (diameter 4.4 +/- 2.8 micron), which when injected directly into the descending aorta are distinctly visualized by renal ultrasound. Five dogs were studied. Catheters were placed in the descending aorta for injection of sonicated Renografin and in the renal artery for drug infusions. Data were collected before and during intrarenal artery infusions of bradykinin and norepinephrine. Total RBF was measured by electromagnetic flowmeter. Video density time curves were generated for comparable segments of the outer renal cortex and fit to a monoexponential decay curve. This allowed calculation of the mean exponential decay index (t1/2). An increase in t1/2 paralleled decreased renal perfusion (i.e., longer washout of contrast material). The opposite was true for a decrease in t1/2. Bradykinin increased RBF from 134 +/- 26 to 249 +/- 19 ml/min (p less than .01 vs control), and norepinephrine decreased RBF from 130 +/- 25 to 51 +/- 17 ml/min (p less than .01 vs control).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Automated production and analysis of echo contrast agents.

To develop and standardize contrast agents for use in contrast echocardiographic imaging, microbubble size, concentration, decay, and ultrasound backscatter must be known. These parameters were assessed with a scanning laser particle counter, a commercial ultrasound unit, and various sonicated intravenous solutions. The scanning laser particle counter proved to be a fast and effective means of evaluating microbubble size, concentration, and stability. In addition, sonication was found to be a reliable and reproducible technique for preparing standardized echo contrast agent solutions containing uniformly small microbubbles. The bubbles generated ranged in size from 1 to 15 micron in diameter. All solutions had mean bubble diameters less than 6 micron. The half life of solutions ranged from 44 +/- 12 seconds for Hypaque 50%, to 253 +/- 73 seconds for Iopamidol. Addition of the surfactant to dextrose 70% prolonged bubble half life from 58 +/- 12 seconds to 1018 +/- 276 seconds. Phased array two-dimensional echocardiography of sonicated microbubble solutions, and subsequent videodensitometric analysis, revealed that bubble concentration was directly proportional to echo-reflective properties, and that the solutions have significant ultrasound reflective properties in vitro at concentrations of less than 1500 bubbles/ml.

Autoanalysis↗
PubMed1986

Quantitation of echo-contrast effects.

With the recent development of sonicated microbubble echocardiographic contrast agents, it is now reasonable to attempt to quantitate actual tissue perfusion. However, this requires an understanding of the quantitative relationship between microbubble concentrations and the reflected ultrasound signal. This paper describes (1) the basic acoustic properties of sonicated microbubbles, and (2) experimental verification of this relationship, showing that the ultrasound signal actually begins to decrease at a critical concentration that may be predicted based upon bubble size. These microbubbles have acoustic properties that are essentially those of a random collection of Rayleighian scatters. Signal strength is governed primarily by the compressibility of gas, as opposed to fluid. In addition, bubble diameter is an important factor in determining signal strength (sixth power dependence). And, because the bubbles are randomly arranged, the reflected signal is not as great as might be expected, when compared to the signal reflected by a single bubble. A simple in vitro test of the acoustic analysis confirmed the critical limit for bubble concentration, the measurement of which led to a prediction for sonicated microbubble size that is within a factor of two of the published values. This acoustic analysis and confirmation, along with ongoing in vivo experimentation, promises to make possible quantitative regional perfusion measurement employing sonicated contrast agents.

Contrast Media↗
PubMedDate not supplied

Capturing the semantic relationship between clinical terms with current MeSH bibliographic coding.

This paper compares bibliographic retrieval using current MeSH (Medical Subject Headings) to bibliographic retrieval using explicitly coded semantic relationships between index terms. In a previous study, ten lists of abstracts, each list containing 20-40 papers discussing a specific pair of terms, were analyzed to identify the specific relationship(s) between those terms discussed in each paper. In the present study, we analyze how well current MeSH coding using topical subheadings and check tags, can selectively retrieve those papers discussing each semantic relationship.

Abstracting and Indexing↗