Biomedical subjects

A Thurin

Publications and source records attributed to A Thurin.

4 recordsLinked to original sources

PubMed2005

Predictors of ongoing implantation in IVF in a good prognosis group of patients.

BACKGROUND: The aim of this study was to investigate whether, in a large randomized trial, it is possible to identify specific maternal and/or embryo variables that could independently correlate with ongoing implantation in IVF/ICSI. METHODS: In a Scandinavian study, 661 women were randomized to elective single embryo transfer or double embryo transfer. Women aged <36 years undergoing their first or second IVF cycle and with at least two good quality embryos were eligible. Only one cycle per subject was included. In the present study, cycles with 0 or 100% ongoing implantation (n = 520) were analysed regarding maternal and embryo variables. RESULTS: In this selected study group, the ongoing implantation rate was 195/734 (26.6%). In the univariate analysis, first IVF cycle, conventional IVF as fertilization method and 4-cell embryos showed a statistically higher ongoing implantation rate than did second IVF cycle, ICSI and non-4-cell embryos. In the multivariate analysis the same variables correlated independently to ongoing implantation. In addition, ovarian sensitivity correlated independently to ongoing implantation. CONCLUSION: This information should be used when selecting the number of embryos for transfer with the overall aim to reduce the rate of multiple births while maintaining a satisfactory birth rate.

Adult↗

PubMed1996

Valvular function of peripheral veins after hyperemic dilation.

PURPOSE: We wanted to answer the question of whether physiological dilation of normal extremity veins can induce temporary valvular leakage and reflux. METHODS: Directional flow was recorded in 22 forearm and popliteal veins by Doppler duplex scanning after distal compression. Reflux was assessed by valve closure time and calculation of a "reflux index," the ratio of backward to forward flow areas. RESULTS: Hyperemia and enhanced flow did not increase but lowered reflux. During control conditions the mean reflux ratio (backward/forward flow area) of 21 veins was 0.058 and decrease to 0.028 (p < 0.05). Reflux was slightly longer in patients in the erect position in the popliteal vein, compared to forearm veins (with the patients in the sitting position). Significantly increased reflux occurred during hyperemia in only one deep forearm vein (valve closure time 0.92 seconds). CONCLUSIONS: Most veins of the upper (forearm) and lower extremity (popliteal vein) were competent even after a maneuver that induced venodilation and an increase in blood flow (exercise hyperemia or postocclusion reactive hyperemia). Veins with an inherent valvular weakness can be identified by a hyperemia test with duplex flow analysis.

Adolescent↗

PubMed1995

Arden syntax and GALEN terminology support: a powerful combination to represent medical knowledge.

Arden syntax is an ASTM standard defined a few years ago to represent rule-based knowledge in the medical domain in an application- and implementation-independent way. Knowledge is expressed as Medical Logic Modules (MLMs). So far, it has mainly been used for providing critique and reminders in data driven, medical decision support systems, where typically rules are evoked by certain database operations (e.g., "store systolic blood pressure"). The syntax is an important step towards a general medical knowledge representation, with version control, maintenance information, arithmetic operations, logic rule syntax, and temporal operations, but it is not yet complete. The standard does not define how medical concepts (e.g., "systolic blood pressure") are to be referenced. Existing coding schemes such as SNOMED and ICD10 may be used for this, but they have generally failed to provide the required level of detail. The use of Arden syntax to transfer knowledge between centers in the form of MLMs has been shown to be non-trivial [1,2]. GALEN (Generalized Architecture for Languages, Encyclopedias, and Nomenclatures in Medicine) is an EC AIM project aiming at a machine-readable system to represent medical concepts in a semantic network. The network allows for the combination and specialization of concepts to the required level of detail. The project has resulted in a notation (GRAIL: GALEN Representation and Integration Language) and several tools, such as browsers for manipulating medical concepts. In a GALEN subproject, we are exploring the potential utility of combining Arden syntax with semantics from the GALEN terminology, and we are developing tools to facilitate the creation of MLMs with terminology support. Our impression is that the combination is very useful: GALEN tools allow a domain expert to express her knowledge in purely medical terms, independent of an actual or intended patient database structure and data representation. They can also help a knowledge engineer or quite possibly an automatic interpreter to translate a well defined medical concept (expressed in GRAIL) to actual database queries (in SQL or other notation). This translation can be facilitated by a Data Dictionary describing the local patient database.

Expert Systems↗

PubMedDate not supplied

Terminology support for development of sharable knowledge modules.

Lack of an agreed infrastructure for terminology is identified as one of the major barriers to interchange of knowledge modules and integration of knowledge bases with other clinical information systems. The goal of the GALEN project is to bridge this gap between different terminology systems through the construction of a terminology server, which is based on a rich conceptual model with mapping facilities to natural language expressions and coding schemas. The long term goal is to support communication between medical information systems. Arden Syntax is a standard format for the creation of knowledge modules, with sharability as one of the main objectives. Since Arden Syntax is based on a data-driven approach, the data items used need to be adapted to locally available terminology. The GALEN approach appears to be complementary to Arden Syntax and to the development of sharable knowledge modules. The major theme of this paper is utilization of the GALEN terminology server for knowledge module authoring. Two systems are presented, a knowledge base manager and a client to the terminology server, allowing the user to navigate in the semantic network and to import concept definitions and terms into the knowledge modules. The benefit of the terminology server, allowing the user to navigate in the semantic network and to import concept definitions and terms into the knowledge modules. The benefit of the terminology services is discussed.

Artificial Intelligence↗