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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 167 (1969), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Respiration Physiology 21 (1974), S. 341-350 
    ISSN: 0034-5687
    Keywords: Acetazolamide ; Carbon dioxide ; Carbonic anhydrase ; Facilitated transport ; Skeletal muscle
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Respiration Physiology 23 (1975), S. 311-316 
    ISSN: 0034-5687
    Keywords: Acetazolamide ; Facilitates transport Carbon Dioxide ; Myocardium
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: Keywords Coronary atherosclerosis ; coronary artery disease ; macrovascular complications ; cardiac mortality ; atherosclerosis ; cardiovascular risk factors.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. Prevalence and incidence of coronary heart disease (CHD) are increased in patients with Type II (non-insulin-dependent) diabetes mellitus; whether this is entirely due to more extensive coronary atherosclerosis is, however, controversial. Methods. We analysed the clinical, angiographic and follow-up data of 2253 consecutive patients undergoing coronary angiography over the decade 1983–1992. Results. Abnormal coronary arteries (≥ 50 % stenosis) were found more frequently in diabetic than in non-diabetic subjects (85 vs 67 %, p 〈 0.0001), the excess being explained by a higher prevalence of three-vessel disease (36 vs 17 %, p 〈 0.0001). The sum of all angiographically detectable lumen stenoses (atherosclerosis score, ATS) was higher in diabetic than in non-diabetic subjects (352 ± 232 vs 211 ± 201 units, p 〈 0.0001). After adjusting for measured cardiovascular risk factors, diabetes was still associated with an excess ATS (114 units in men and 187 units in women, p 〈 0.0001 for both, p 〈 0.03 for the interaction ATS x sex). Within the diabetic group, the only variable that was independently (of sex and age) associated with ATS was serum cholesterol, whereas plasma glucose concentration, disease duration and type of treatment were not correlated with the severity of coronary atherosclerosis. In contrast, clinical grade proteinuria was not associated with a more diffuse coronary atherosclerosis either in diabetic (366 ± 243 vs 354 ± 233 units) or non-diabetic subjects (231 ± 201 vs 207 ± 197 units). Over a mean follow-up period of 88 months, 19 % of diabetic patients compared with 10 % of non-diabetic patients died of a cardiac cause (age and sex-adjusted odds ratio OR = 1.34 [1.14–1.57]). In a Cox model adjusting for age, sex and all major risk factors, diabetes was still associated with a significant excess risk of dying of a cardiac cause (OR = 1.37 [1.14–1.60]); this excess was similar to, and independent of, that carried by the presence of prior myocardial infarction in the whole population (OR = 1.42 [1.25–1.62]). Proteinuria was associated with a higher risk of cardiac death, particularly in diabetic patients, independently of coronary atherosclerosis (adjusted OR = 1.46 [1.03–1.99]). Conclusion/interpretation. In patients undergoing angiography, diabetes, especially in women, is associated with more severe and diffuse coronary atherosclerosis which is not explained by either the traditional risk factors or the presence of proteinuria. On follow-up, these patients experience an excess of cardiac deaths, to which coronary atherosclerosis and proteinuria make independent, quantitative contributions. [Diabetologia (2000) 43: 632–641]
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The international journal of cardiovascular imaging 9 (1993), S. 7-19 
    ISSN: 1573-0743
    Keywords: contrast agents ; echocardiography ; indicator-dilution principles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Contrast echocardiography has the potential for measuring cardiac output and regional blood flow. However, accurate quantitation is limited both by the use of non-standard contrast agents and by the electronic signal distortion inherent to the echocardiographic instruments. Thus, the aim of this study is to quantify flow by combining a stable contrast agent and a modified echo equipment, able to sample the radio frequency (RF) signal from a region of interest (ROI) in the echo image. The contrast agent SHU-454 (0.8 ml) was bolus injected into anin vitro calf vein, at 23 flow rates (ranging from 376 to 3620 ml/min) but constant volume and pressure. The ROI was placed in the centre of the vein, the RF signal was processed in real time and transferred to a personal computer to generate time-intensity curves. In the absence of recirculation, contrast washout slope and mean transit time (MTT) of curves (1.11–8.52 seconds) yielded excellent correlations with flow: r=0.93 and 0.95, respectively. To compare the accuracy of RF analysis with that of conventional image processing as to flow quantitation, conventional images were collected in the same flow model by two different scanners: a) the mechanical sector scanner used for RF analysis, and b) a conventional electronic sector scanner. These images were digitized off-line, mean videodensity inside an identical ROI was measured and time-intensity curves were built. MTT by RF was shorter than by videodensitometric analysis of the images generated by the same scanner (p〈0.001). In contrast, MTT by RF was longer than by the conventional scanner (p〈0.001). Significant differences in MTT were also found with changes in the gain setting controls of the conventional scanner. To study the stability of the contrast effect, 6 contrast injections (20 ml) were performed at a constant flow rate during recirculation: the spontaneous decay in RF signal intensity (t1/2=64±8 seconds) was too long to affect MTT significantly. In conclusion, the combination of a stable con trast agent and a modified echocardiographic instrument provides accurate quantitation of flow in anin vitro model; RF analysis is more accurate than conventional processing as to flow quantitation by contrast echocardiography.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für Kardiologie 89 (2000), S. 126-131 
    ISSN: 1435-1285
    Keywords: Key words Coronary blood flow – myocardial ischemia – coronary atherosclerosis – coronary artery disease – microcirculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The hallmark of ischemic heart disease is the presence of focal obstructions in the major coronary arteries. Classically, epicardial stenoses are thought to exert their pathogenetic role mainly through a limitation on maximal flow capacity in the distal vascular bed. Ischemia is thus thought to occur whenever oxygen consumption exceeds the flow availability. Although a number of experimental studies confirmed these assumptions, the adherence of this experimental model with the clinical observations is still far from being convincing. Evidence now exists that atherosclerosis causes more profound alterations in the regulation of myocardial perfusion, besides the hydraulic effects of epicardial obstructions. These alterations affect endothelial regulation of coronary vasomotor tone both in the large arteries and in the distal microcirculation. In agreement with this experimental evidence, an abnormal response to endothelium-mediated vasodilators has been reported in patients with coronary artery disease. Moreover, several studies also reported an abnormal response of atherosclerotic coronary microcirculation to atrial pacing tachycardia and dipyridamole, which are thought to be largely endothelium independent. An even more striking observation is the finding of an intense microvascular constrictor response in the myocardium, supplied by a severely stenotic coronary artery, to pacing-induced ischemia. This observation strongly suggests that coronary microcirculation might aggravate the flow reduction imposed by the epicardial stenosis, thus playing some role in the pathogenesis of ischemia. This phenomenon might reflect the presence of a primary abnormality of coronary microcirculation in patients with coronary artery disease or the existence of a pressure-oriented regulation of vascular tone which prevent trans-stenotic pressure drop by means of a heterogeneously distributed microcirculatory vasoconstriction.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The international journal of cardiovascular imaging 9 (1993), S. 21-27 
    ISSN: 1573-0743
    Keywords: attenuation ; contrast agents ; echocardiography ; indicator-dilution principles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The combination of a standardized echographic contrast agent with the analysis of the ultrasonic radio frequency (RF) signal allowedin vitro flow quantitation in a circulation model. The purpose of this study was to investigate both the effects of biological tissues, intervening between probe and insonated structure, and the effects of the angle of incidence between flow and ultrasonic beam on RF flow quantitation. Thus, the contrast agent SHU 454 was intravenously injected (0.4 ml) as a bolus into a circulation model, at variable flow rates, while keeping the pressure and volume of the vessel constant. Injections were performed with saline interposed between probe and vessel and after the addition of the subcutaneous tissue of a pig; injections were also performed using the probe normal to the flow and with an angle of incidence of 45°. Echographic data were recorded by a mechanical sector scanner, capable of sampling the RF signal from a region of interest positioned in the center of the vein. Contrast echo time-intensity curves were generated. As expected, both peak intensity and the area under the curves decreased with intervening tissue (− 58 and − 70% of baseline values, respectively, p〈0.001). Surprisingly, mean transit time also decreased with intervening tissue (from 1.12±0.25 seconds with saline, to 0.92±0.13 seconds with tissue, p〈0.001), thus producing a systematic overestimation of flow (21% on the average). To compensate for signal attenuation, contrast injections were repeated in the presence of tissue after increasing the electronic signal amplification (10 dB), and transit time did not significantly differ from control. Moreover, mean transit time was slightly shorter with an angle of 45° (1.03 ° 0.19 seconds) than with an angle of 90° (1.12±0.25 seconds, p〈0.05). However, when the data collected with both angles of incidence were plotted together, the correlation with flow remained very close (r=0.94). In conclusion: intervening tissue influences flow quantitation by contrast echocardiography: these modifications can be compensated for by increasing the electronic signal amplification; the angle of incidence between flow and ultrasonic beam also influences flow quantitation: however, this influence is trivial, and can be neglected for practical purposes.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 76 (1981), S. 394-398 
    ISSN: 1435-1803
    Keywords: regional myocardial metabolish ; regional myocardial flow ; autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1435-1803
    Keywords: myocardial mitochondria ; palmitic acid oxidation rate ; pyruvic acid oxidation rate ; Krebs cycle enzymes ; beta-oxidation enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Mitochondria were prepared from the subendocardial and subepicardial layers of the canine left ventricle. The oxidation rates of palmitate, palmitoyl carnitine and pyruvate of the mitochondria obtained from the two cardiac layers were measured. The cytochrome content and the specific activities of different beta oxidation and Krebs cycle enzymes were also measured in the two mitochondrial populations. Mitochondria isolated from the ENDO layer showed significantly higher oxidation rates than mitochondria from the EPI layer for all the three substrates. No statistically significant differences in cytochrome c+c1 and a+a3 content were found in mitochondria isolated from the two regions. No significant transmural differences were found in fatty acyl CoA, L-3-hydroxy fatty acyl CoA, succinic and malic dehydrogenase specific activities, whilst isocitric dehydrogenase (NADP) specific activity was significantly higher in mitochondria isolated from the inner layer. In conclusion, the mitochondria isolated from the inner left ventricular layer of the canine heart show a higher oxidative capacity than subepicardial mitochondria. This difference could partly be explained by the higher specific activity of isocitric dehydrogenase in this layer. These properties of subendocardial mitochondria could represent a metabolic support for the greater contractile performance of this layer.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1435-1803
    Keywords: Afferents ; cardio-cardiac reflex ; deoxyglucoseuptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of this study was to evaluate the effect of autonomic reflexes as initiated by stimulation of the right recurrent cardiopulmonary nerve afferent axons on myocardial deoxyglucose uptake and to determine how such uptake can be modified by selective neural ablation. The afferent axon in the right recurrent cardiopulmonary nerve was stimulated 30 s/min for 1 h in five anesthetized open-chest dogs in which 14-C labeled deoxyglucose was i.v. injected at the beginning of the stimulation period. Three additional sham-operated dogs served as neurally intact controls. Concentrations of label and glucose were measured in plasma. Regional myocardial deoxyglucose concentration was measured by quantitative autoradiography, following the calibration of plasma samples autoradiographic density by β counting. Stimulation of right recurrent cardiopulmonary nerve afferent axons in the intact nervous system preparation did not significantly enhance deoxyglucose uptake as compared to neurally intact controls. When the right cervical vagosympathetic complex was cut a similar uptake was observed. Following decentralization of the right stellate ganglion, uptake was markedly reduced, as well as when the right cervical vagosympathetic was cut and the right stellate ganglion decentralized. Conclusions: Activation of afferent axons from cardiopulmonary receptors does not alter myocardial deoxyglucose uptake. Reducton in uptake occurs following unilateral stellate ganglion decentralization.
    Type of Medium: Electronic Resource
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