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Biomedical subjects

C Pappas

Publications and source records attributed to C Pappas.

At least 19 recordsLinked to original sources
PubMed2000

Effect of intracoronary gamma-radiation therapy on in-stent restenosis: An intravascular ultrasound analysis from the gamma-1 study.

BACKGROUND: The aim of this study was to use serial volumetric intravascular ultrasound to evaluate the effect of gamma-radiation on recurrent in-stent restenosis. METHODS AND RESULTS: After successful reintervention, patients were randomized to receive either (192)Ir or placebo. Intravascular ultrasound studies with motorized pullback (0.5 mm/s) were performed immediately after irradiation and at 8-month follow-up in 70 patients. Paired volumetric analysis of the stented segment and of 5-mm proximal and distal reference segments was performed; this included measurements of the external elastic membrane, lumen, plaque and media (external elastic membrane minus lumen), stent, and intimal hyperplasia (stent minus lumen). Baseline proximal reference, stent, and distal reference measurements were similar in both groups. The changes in proximal and distal reference measurements of the external elastic membrane, plaque and media, and lumen areas were similar in both groups. However, the decrease in stented segment lumen volume was less in the (192)Ir patients than the placebo patients (-25+/-34 mm(3) versus -48+/-42 mm(3); P:=0.0225), and the increase in the volume of intimal hyperplasia in the stented segment was less in the (192)Ir patients than in the placebo patients (28+/-37 mm(3) versus 50+/-40 mm(3); P:=0.0352). When averaged over the length of the stented segment (32+/-13 mm versus 33+/-14 mm; P:=0.9), the increase in mean area of intimal hyperplasia was 0.8+/-1.0 mm(2) in the (192)Ir group and 1.6+/-1.2 mm(2) in the control group (P:=0.0065). Late stent-vessel wall malapposition was noted in one placebo patient and no (192)Ir patients. CONCLUSIONS: gamma-Radiation therapy can effectively prevent recurrent in-stent restenosis by inhibiting neointimal formation within the stent. At the stent edge, there were no significant differences between (192)Ir and placebo patients.

Analysis of Variance↗
PubMed2000

Decay of methidathion on Greek soultanina grapes during storage and on the vines.

Decomposition of the pesticide methidathion on and in soultanina (Thomson seedless) grapes was studied. Vines, uncovered and covered were sprayed with the pesticide. Samples were collected and analyzed in regular time intervals. Two lots were collected, the first of them, 2 h after spraying and the second 20 days later, and were stored in a commercial refrigerated room. Degradation of the pesticide was studied for about 50 days for the grapes on the vines and 130 days for the grapes stored in the refrigerated room. The half-life of the pesticide methidathion was found to be 5 days for the uncovered vines, 7 days for the covered vines and 64 days for the grapes stored in the refrigerator.

Chromatography, Gas↗
PubMed2000

Evaluation of heterodimeric guanylyl cyclase genes as candidates for human hypertension.

OBJECTIVE: Both physiologic and pharmacological data have implicated the nitric oxide (NO) signaling cascade in the regulation of blood pressure in humans and its impairment in the pathogenesis of hypertension. In biological systems, the principal receptor for NO is NO-stimulated guanylyl cyclase. NO-stimulated guanylyl cyclases are obligate heterodimers (alpha/beta). The genes for guanylyl cyclase subunits alpha1, beta, and beta2 are likely candidates for causing hypertension in the Dahl rat as their expression is altered and their gene loci are closely linked to known quantitative trait loci for blood pressure in Dahl rat crosses. The objective of the current study was to test whether markers near guanylyl cyclase subunit genes were linked to hypertension in Caucasians. DESIGN: To test for linkage of genetic markers in or near the guanylyl cyclase genes to hypertension in Caucasians, a sample of 124 Utah hypertensive sib pairs was genotyped. RESULTS: Four highly polymorphic markers in or near the human guanylyl cyclase subunits homologous to the rat alpha1 (human chromosome 8), rat beta1 (human chromosome 4), and rat beta2 (human chromosome 13) genes showed no evidence of excess allele sharing in the set of hypertensive sibships. CONCLUSION: We conclude that the heterodimeric guanylyl cyclase subunit loci do not appear to be linked to hypertension in Caucasians.

Adult↗
PubMed2000

Spatial filtering methods for local activation determination in fractionated electrograms from simulated infarcted hearts.

The purpose of this work is the enhancement of local activation in multiphasic extracellular recordings coming from infarcted myocardial tissue and, consequently, the distinction of local from distal activation. Deconvolution procedures are applied, in the form of spatial filtering, in order to estimate transmembrane currents from the extracellular recordings. Simulated data are used in order to test the methods. The current source estimates are compared to the actual transmembrane currents and to Laplacian estimates.

Computer Simulation↗
PubMed2000

Prospects of medical informatics education in Greece: can we bridge the gap?

Medical Informatics education is a complex task,, since it aims in educating inhomogeneous groups of people coming from different disciplines. In Greece, recently considerable advancements in the medical informatics education field are made. These advancements aim in bridging gaps in various areas of MI users interactions. In particular, an overview of the strategy of the Greek ministry of education shall be given, some examples of MI related educational programs shall be referred to, and finally the MI educational structure used in the Aristotelian University shall be presented in detail, laying out the strategy of this University for bridging various types of gaps.

Curriculum↗
PubMed1999

Long-term follow-up after percutaneous transluminal coronary angioplasty was not performed based on intravascular ultrasound findings: importance of lumen dimensions.

BACKGROUND: Angiography is limited in determining the anatomic severity of coronary artery stenoses. Clinical decision-making in patients with symptoms and intermediate lesions remains challenging. METHODS AND RESULTS: The current analysis included 300 patients (357 intermediate native artery lesions) in whom intervention was deferred based on intravascular ultrasound (IVUS) findings. Standard clinical, angiographic, and IVUS parameters were collected. Patients were followed for >1 year. Events occurred in 24 patients (8%). They included 2 cardiac deaths, 4 myocardial infarctions, and 18 target-lesion revascularizations (TLR; 12 percutaneous transluminal coronary angiographies and 6 coronary artery bypass grafts; only 3 TLRs occurred within 6 months after the IVUS study). All significant univariate clinical, angiographic, and IVUS parameters (P<0.05) were tested in multivariate models. These included diabetes mellitus, IVUS lesion lumen area, maximum lumen diameter, minimum lumen diameter, plaque area, plaque burden, and area stenosis (AS). No angiographic measurement was significant at P<0.05. The only independent predictors of an event (death, myocardial infarction, or TLR) were IVUS minimum lumen area and AS. The only independent predictors of TLR were diabetes mellitus, IVUS minimum lumen area, and AS. In 248 lesions with a minimum lumen area >/=4.0 mm(2), the event rate was only 4.4% and the TLR rate 2.8%. CONCLUSIONS: Long-term follow-up after IVUS-guided deferred interventions in patients with de novo intermediate native artery lesions showed a low event rate. In patients with a minimum lumen area >/=4.0 mm(2), the event rate was especially low. IVUS imaging is an acceptable alternative to physiological assessment in these patients.

Angioplasty, Balloon, Coronary↗
PubMed1999

A locus for febrile seizures (FEB3) maps to chromosome 2q23-24.

Febrile seizures are the most common form of childhood seizures, occurring in 2% to 5% of North American children. We report a large Utah family with 21 members affected by febrile seizures inherited as an autosomal dominant trait. All had generalized tonic-clonic seizures with onset associated with fever, consistent with the consensus febrile seizure phenotype, and none had febrile seizures beyond 6 years of age. Eighteen affected individuals had recurrent febrile seizures. Eight individuals developed afebrile seizures between ages 5 and 13 years. Afebrile seizures consisted of generalized tonic-clonic, generalized tonic, generalized atonic, simple partial, and partial complex seizure types and were associated with abnormal electroencephalographic findings in 5 individuals, all of whom were intellectually normal. We undertook linkage analysis in this family, defining the disease phenotype as febrile seizures alone. Linkage analysis in epilepsy candidate gene/loci regions failed to show evidence for linkage to febrile seizures. However, a genomewide scan and subsequent fine mapping revealed significant evidence for a new febrile seizure locus (FEB3) on chromosome 2q23-24 with linkage to the marker D2S2330 (LOD score 8.08 at theta = 0.001). Haplotype analysis defined a critical 10-cM region between markers D2S141 and D2S2345 that contains the FEB3 locus.

Chromosome Mapping↗
PubMed1999

Model-based morphological segmentation and labeling of coronary angiograms.

A method for extraction and labeling of the coronary arterial tree (CAT) using minimal user supervision in single-view angiograms is proposed. The CAT structural description (skeleton and borders) is produced, along with quantitative information for the artery dimensions and assignment of coded labels, based on a given coronary artery model represented by a graph. The stages of the method are: 1) CAT tracking and detection; 2) artery skeleton and border estimation; 3) feature graph creation; and iv) artery labeling by graph matching. The approximate CAT centerline and borders are extracted by recursive tracking based on circular template analysis. The accurate skeleton and borders of each CAT segment are computed, based on morphological homotopy modification and watershed transform. The approximate centerline and borders are used for constructing the artery segment enclosing area (ASEA), where the defined skeleton and border curves are considered as markers. Using the marked ASEA, an artery gradient image is constructed where all the ASEA pixels (except the skeleton ones) are assigned the gradient magnitude of the original image. The artery gradient image markers are imposed as its unique regional minima by the homotopy modification method, the watershed transform is used for extracting the artery segment borders, and the feature graph is updated. Finally, given the created feature graph and the known model graph, a graph matching algorithm assigns the appropriate labels to the extracted CAT using weighted maximal cliques on the association graph corresponding to the two given graphs. Experimental results using clinical digitized coronary angiograms are presented.

Algorithms↗
PubMed1999

DIABCARD core system--a chip card medical information system for diabetes care.

A chip card based medical information system was developed as a good possibility to create a portable electronic patient record. The produced software module provides an on-line, portable diabetes medical record information system. In particular the patient data card makes the up-to-date patient's record available whenever needed. The developed Core System includes a patient record management system that has the ability to handle topics such as medical anamnesis, administrative, medical and physical examination data. Issues tackled were simplicity, data security and reporting. Customization and internationalization were also covered by presenting a novel approach using native initialization files. Proper care has been addressed during the development of the software modules for matters of security, data integrity and confidentiality.

Computer Security↗
PubMed1998

An adaptive backpropagation neural network for real-time ischemia episodes detection: development and performance analysis using the European ST-T database.

A supervised neural network (NN)-based algorithm was used for automated detection of ischemic episodes resulting from ST segment elevation or depression. The performance of the method was measured using the European ST-T database. In particular, the performance was measured in terms of beat-by-beat ischemia detection and in terms of the detection of ischemic episodes. The algorithm used to train the NN was an adaptive backpropagation (BP) algorithm. This algorithm drastically reduces training time (tenfold decrease in our case) when compared to the classical BP algorithm. The recall phase of the NN is then extremely fast, a fact that makes it appropriate for real-time detection of ischemic episodes. The resulting NN is capable of detecting ischemia independent of the lead used. It was found that the average ischemia episode detection sensitivity is 88.62% while the ischemia duration sensitivity is 72.22%. The results show that NN can be used in electrocardiogram (ECG) processing in cases where fast and reliable detection of ischemic episodes is desired as in the case of critical care units (CCU's).

Algorithms↗
PubMed1998

An integrated environment for ECG processing.

The huge amount of information involved in clinical cardiological examination raises the need for efficient patient data management and for the fusion of modern information processing techniques in the everyday clinical workstation. An integrated medical information system has been developed in order to organize the local cardiological legacy system in the AHEPA hospital. An ODBC based database (like Ms SqlServer or MSAccess) holds patient and ECG data. The system incorporates data management (storing and retrieval) and data processing modules. The processing module is added as an independent DLL. The visualization component results in a better view of the information. The components are integrated in a friendly window interface that lets the doctor browse patient information, apply modern signal processing techniques, make special measurements and store them in the database for research reasons.

Database Management Systems↗
PubMed1997

Identification of computer-generated facial composites.

Two studies examined the effectiveness of the Mac-a-Mug Pro, a computerized facial composite production system. In the first study, college freshmen prepared from memory composites of other students and faculty from their former high schools. Other students who had attended the same high schools could not recognize the composites of either students or faculty members when the composites of individuals known to them (n = 10) were mixed with composites of a large number (n = 40) of strangers. Neither preparer familiarity with the target, preparer-assessed composite quality, nor viewer familiarity predicted composite recognition. Study 2 indicated that naive witnesses who viewed the composites could not select the people depicted in the composites from photo lineups (1 target and 4 foils). The results raise questions about the efficacy of composite systems as tools to promote recognition of suspects in criminal contexts.

Adolescent↗