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213. ANATOMICAL PROGRESSION OF CORONARY-ARTERY DISEASE IN HUMANS AS SEEN BY PROSPECTIVE, REPEATED, QUANTITATED CORONARY ANGIOGRAPHY - RELATION TO CLINICAL EVENTS AND RISK-FACTORS

Author

LICHTLEN, PR, NIKUTTA, P, JOST, S, DECKERS, J, WIESE, B, RAFFLENBEUL, W, NELLESSEN, U, AMENDE, [No Value], HAMM, C, KALTENBACH, M, KLEPZIG, H, KOBER, G, BACHMANN, K, HAETINGER, S, WERNER, H, SCHMUTZLER, H, BIAS, H, SERRUYS, P, REIBER, H, BONNIER, H, MICHELS, R, TROQUAY, R, LIE, K, DEMUINCK, ED, SCHNEIDER, B, HECKER, H, and Faculteit Medische Wetenschappen/UMCG

Subjects
ACUTE MYOCARDIAL-INFARCTION, UNSTABLE ANGINA, ANGIOGRAPHY, CORONARY, MYOCARDIAL INFARCTION, ISOSORBIDE DINITRATE, HEART-DISEASE, NATURAL-HISTORY, OCCLUSION, CORONARY ARTERY, CHEWING CAPSULES, RISK FACTORS, CORONARY, CORONARY ARTERY DISEASE, HIGH-DENSITY LIPOPROTEIN, CIGARETTE-SMOKING, FOLLOW-UP, PLASMA-LEVELS
Abstract

Background. At present, there is extensive knowledge on the clinical course of coronary artery disease (CAD), whereas data on the underlying anatomical changes and their relation to clinical events are still limited. Methods and Results. We investigated progression and regression of CAD prospectively over 3 years in 230 patients (average age, 53.2 years) with mild to moderate disease by applying quantitated, repeated coronary angiography. Minimal stenotic diameters, segment diameters, and percent stenosis were analyzed by the computer-assisted Coronary Angiography Analysis System (CAAS). Progression was defined either as an increase in percent stenosis of preexisting stenoses by greater-than-or-equal-to 20% including occlusions or as formation of new stenoses greater-than-or-equal-to 20% and new occlusions in previously angiographically "normal" segments. At first angiography, we found 838 stenoses greater-than-or-equal-to 20% (average degree, 39.3%) and 135 occlusions in the four major coronary branches (4.23 lesions per patient). At second angiography, 82 (9.8%) of the preexisting stenoses had progressed, 15 of them up to occlusion (1.8%; preocclusion degree averaging 46.6%; 29.7-65.6%). In addition, there were 144 newly formed stenoses (average degree, 39.2%) and 10 new occlusions. Hence, 25 (2.6%) of all stenoses had become occluded. Altogether, 129 patients (56.1%) showed progression: 68 (29.6%) with new lesions only, 27 (11.7%) with preexisting lesions, and 34 (14.8%) with both types. Regression (decrease in degree of stenoses greater-than-or-equal-to 20%) was present in 29 stenoses (3.6%) and 28 patients (12%). The incidence of new myocardial infarctions was low, with three originating from occluding preexisting stenoses and one from new stenoses; hence, only four (16%) of the 25 new occlusions led to myocardial infarctions. Risk factor analysis showed that cigarette smoking correlated significantly with the formation of new lesions (p=0.001), whereas total cholesterol correlated with the further progression of preexisting stenoses (p=0.017) but not with the incidence of new lesions. Conclusions. In patients with mild to moderate CAD, the angiographic progression is slow (in this study 18.7% of patients and 7% of stenoses per year) but exceeds regression (4.1% of patients and 1.2% of stenoses per year). Progression is predominantly seen in the formation of new coronary stenoses and less in growth of preexisting ones. Most of the stenoses were of a low degree (

Published
1992

215. Blood and plasma viscosity in diabetes: possible contribution to late organ complications?

Author

Schut, N. H., van Arkel, E. C., Hardeman, M. R., Bilo, H. J., Michels, R. P., Vreeken, J., and Other departments

Abstract

It has been postulated that an increased whole blood and plasma viscosity contribute to diabetic organ complications. Blood viscosity was measured in 30 controls and four groups of insulin-dependent diabetic patients at three shear rates: 70 sec-1, 0.5 sec-1 and 0.05 sec-1. Results were compared before and after correction for a haematocrit of 0.45. Twenty-five patients without organ complications, 21 with microalbuminuria, 13 with overt nephropathy and 12 patients with leg ulcerations were studied. Blood and plasma viscosity were normal in the patients without organ complications and with microalbuminuria. Plasma viscosity was significantly elevated in the diabetic patient with nephropathy and leg ulceration. After correction for haematocrit blood viscosity was also higher in these two groups, although this was only significant in the group with leg ulceration. In conclusion blood and plasma viscosity were only elevated in the patients with major organ complications and not in the patients without or with early complications. Therefore it is unlikely that an elevation of blood or plasma viscosity contributes early in the pathogenesis of diabetic organ damage

Published
1992

222. Bedrijven binnen bereik: Kwantificering van de bereikbaarheid van werkgelegenheidslocaties in het stadsgewest Haaglanden

Author

Michels, R. (author) and Michels, R. (author)

Abstract

Het succes van werkgelegenheidslocaties is voor een belangrijk deel afhankelijk van een goede bereikbaarheid. Door het ontbreken van gestandaardiseerde maten in de vee! gevoerde discussies over het begrip bereikbaarheid blijkt in de praktijk een behoefte aan standaard methodieken ter kwantificering van de bereikbaarheid. In deze studie zijn drie rekenmethoden geanalyseerd, deels ontwikkeld en getoetst aan de hand van een toepassing van de methoden op drie werkgelegenheidslocaties: Kerketuinen I Zichtenburg, NS station Rijswijk en Binckhorst. De methode PROBER, die uitgaat van de positie van een locatie binnen het infrastructuurnetwerk, kan worden gebruikt als evaluatie van het ABC locatiebeleid. Echter, in de toetsing is geconcludeerd dat door de handmatige verwerking van de gegevens en de niet lineaire scores de methode onvoldoende betrouwbaar is en dus niet wordt aanbevolen voor dagelijks gebruik. De methode "Rekenen aan bereikbaarheid" kent als uitgangspunt de acceptatie van verplaatsingsweerstanden tussen herkomst en bestemming. Hoewel een enkele onnauwkeurigheid kan worden genoemd, geeft deze methode door de verdiscontering van menselijk gedrag en concurrentie tussen vervoerwijzen een goede schatting van de (toekomstige) bereikbaarheid van een locatie. Bij verdere toepassing wordt deze methode aanbevolen. De lsochronenmethode gaat slechts uit van de verplaatsingstijden tussen herkomst en bestemming. De methode Ievert een minder waarheidsgetrouwe weergave van de potentiele bereikbaarheid dan de voorgaande methode, maar kent als groot voordeel de eenvoud. In het geval dat veel onzekerheid betreffende de acceptatie van verplaatsingstijden bestaat, wordt de isochronenmethode aanbevolen. In een integrale afweging van de drie genoemde werkgelegenheidslocaties, waarin naast bereikbaarheid meerdere criteria zijn meegenomen, kwam de locatie Binckhorst als beste naar voren vanuit het gezichtspunt van de bedrijven (gebruikers) en de omgeving (omwonenden). Gezien vanuit he, Transport & Planning, Civil Engineering and Geosciences

Published
1998

233. Behavior of Oxidized Type-ii Kerogen During Artificial Maturation

Author

UCL, Landais, P., Michels, R., Kister, J., Dereppe, Jean-Marie, Benkhedda, Z., UCL, Landais, P., Michels, R., Kister, J., Dereppe, Jean-Marie, and Benkhedda, Z.

Abstract

A series of artificially oxidized type II kerogens (ventilated oven, 140-degrees-C, 8-256 h) from the Paris Basin (France) has been pyrolyzed in cold-seal autoclaves at temperatures ranging between 250 and 450-degrees-C for 24 h at 100 MPa. Oxidates and pyrolysates have been characterized by C-13 solid-state NMR, FTIR spectroscopy, Rock-Eval pyrolysis, elemental analysis, and CHCl3 extraction. Results indicate that oxidation is responsible for an important decrease of the petroleum potential and for the increase of different oxygen-bearing functions' (carbonyl, carboxyl, esters, ethers) concentration. The behavior of the different oxidates during artificial maturation is characterized by two distinct stages: oxygen removal (250-300-degrees-C) and hydrocarbon production (300-450-degrees-C). It is shown that oxidation induces an important decrease of the hydrocarbon yield during maturation and that no regeneration of petroleum potential can be observed. Comparison of the most oxidized kerogen (256 h) with an unoxidized type III coal of similar initial elemental composition has also been carried out.

Published
1991

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