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Biomedical subjects

C Falcone

Publications and source records attributed to C Falcone.

At least 55 records · Page 3Linked to original sources
PubMed1993

Comparison of dobutamine stress echocardiography, dipyridamole stress echocardiography and exercise stress testing for diagnosis of coronary artery disease.

To compare the value of dobutamine and dipyridamole stress echocardiography with exercise stress testing for the diagnosis of coronary artery disease (CAD), 80 patients with chest pain of suspected myocardial ischemic origin (57 with CAD and 23 without significant CAD) underwent dobutamine stress echocardiography (5 to 40 micrograms/kg/min), dipyridamole echocardiography (0.84 mg/kg over 10 minutes) and bicycle exercise electrocardiography after discontinuation of antianginal treatment. Dobutamine echocardiography and exercise testing revealed a higher overall sensitivity than dipyridamole echocardiography (79 vs 60%, p < 0.005; 77 vs 60%, p < 0.05, respectively); this finding was due to a higher dobutamine and exercise sensitivity in 1-vessel CAD (62 vs 33%, p < 0.05 for both tests), whereas sensitivity of the 3 tests was similar in multivessel CAD. Dobutamine and dipyridamole showed a higher specificity than exercise (83 vs 43%, p < 0.01; 96 vs 43%, p < 0.005, respectively). Diagnostic accuracy of dobutamine echocardiography was higher than that of exercise (80 vs 67%, p < 0.05), whereas the difference with dipyridamole (80 vs 70%) was not significant. In the tests that yielded positive results, double product during exercise was significantly higher than that during dobutamine and dipyridamole echocardiography. No major complications occurred during the tests, but adverse effects were more frequent during dobutamine testing. Thus, dobutamine echocardiography may be superior to dipyridamole echocardiography and exercise electrocardiography for the diagnosis of CAD.

Adult↗
PubMed1992

Ethanol-induced and glucose-insensitive alcohol dehydrogenase activity in the yeast Kluyveromyces lactis.

The alcohol dehydrogenase (ADH) system in the yeast Kluyveromyces lactis is encoded by four ADH genes. In this paper we report evidence that at least three of these genes are transcribed and translated into protein. KIADH1 and KIADH2, which encode cytoplasmic activities, are preferentially expressed in glucose-grown cells with respect to ethanol-grown cells. KIADH4, which encodes one of the two activities localized within mitochondria, is induced at the transcriptional level in the presence of ethanol as is the ADH2 gene in Saccharomyces cerevisiae. However the regulation of the expression of the K. lactis gene is completely different from that of ADH2 and of other known ADH genes in that KIADH4 is insensitive to glucose repression and is not expressed on non-fermentable carbon sources other than ethanol. This kind of regulation can be clearly observed in non-fermenting strains, where the induction of KIADH4 is dependent on the addition of ethanol to the medium. On the contrary, in fermenting strains KIADH4 is always induced by ethanol or acetaldehyde produced endocellularly and this results in constitutive expression of the gene also in the presence of glucose. The mitochondrial localization of the activity encoded by KIADH4 and the peculiar regulation of this gene could be related to the fact that K. lactis is a petite negative yeast in which some mitochondrial functions seem to be essential for cell viability.

Alcohol Dehydrogenase↗
PubMed1991

Abnormal coronary vasoconstriction as a predictor of restenosis after successful coronary angioplasty in patients with unstable angina pectoris.

BACKGROUND: High rates of restenosis after coronary angioplasty have been reported in patients with vasospastic angina. This study was designed to determine whether the occurrence of abnormal coronary vasoconstriction, detected by means of hyperventilation testing before angioplasty, influences the risk of restenosis after successful dilation. METHODS: Hyperventilation testing was performed 0 to 4 days before coronary angioplasty in 106 consecutive patients with unstable angina and single-vessel coronary artery disease. Abnormal coronary vasoconstriction was considered present if hyperventilation-induced myocardial ischemia occurred during the recovery phase of the test. All patients had follow-up angiography 8 to 12 months after angioplasty. RESULTS: Abnormal coronary vasoconstriction was observed in 48 patients (group 1), whereas 58 patients (group 2) had either a negative response throughout the test or a positive response only during the overbreathing phase of the hyperventilation test. Angioplasty was successful in 40 patients in group 1 and 51 in group 2. Restenosis was documented in 29 patients (73 percent) in group 1 and 13 (25 percent) in group 2 (relative risk of restenosis, 2.84; 95 percent confidence interval, 1.69 to 4.28; P less than 0.001). In a multivariate analysis, the following three characteristics were independently related to the risk of restenosis (in descending order of importance): ST-segment elevation during spontaneous ischemic attacks (P less than 0.001), hyperventilation-induced abnormal coronary vasoconstriction (P less than 0.001), and the presence of a lesion more than 10 mm long in the left anterior descending coronary artery (P less than 0.05). CONCLUSIONS: In patients with unstable angina and single-vessel coronary artery disease who have been selected for coronary angioplasty, the presence of hyperventilation-induced abnormal coronary vasoconstriction identifies a subgroup at high risk for restenosis.

Angina, Unstable↗
PubMed1991

Mental stress as a provocative test in patients with various clinical syndromes of coronary heart disease.

To assess the prevalence of mental stress-induced myocardial ischemia and investigate the pathogenetic mechanisms by which emotional stress may induce myocardial ischemia, we studied 372 patients with angina pectoris who underwent mental arithmetic and exercise stress testings. Hyperventilation tests were also performed in 176 patients, and 340 patients underwent coronary arteriography. Sixty-one patients showed significant ST segment abnormalities during mental arithmetic and exercise stress testings (group 1). Two hundred eleven patients had negative responses to mental stress but positive exercise tests (group 2), whereas both tests were negative in 100 patients (group 3). Mental stress induced significant increases in heart rate and systolic blood pressure in the three groups of patients; however, group 1 patients had higher increases in rate-pressure product (mm Hg x beats/min) than group 2 and group 3 patients (14,909 +/- 3,894 versus 12,985 +/- 2,900 versus 12,724 +/- 4,400 mm Hg x beats/min, p less than 0.01). Group 1 patients had shorter exercise durations than group 2 or group 3 (4.06 +/- 1.55 versus 7.65 +/- 3.07 versus 13.9 +/- 5.31 minutes, p less than 0.01), although rate-pressure products at peak exercise were similar in groups 1 and 2 (20,277 +/- 6,058 versus 20,768 +/- 3,864, p = NS) and significantly higher in group 3 (26,221 +/- 7,100/mm Hg x beats/min, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1990

Usefulness of the hyperventilation test in stable exertional angina pectoris in selecting medical therapy.

To assess the prevalence of abnormal coronary vasoconstriction in stable exertional angina and to evaluate whether the presence of increased coronary tone may have therapeutic implications, we studied 83 consecutive patients with typical exertional angina, positive response to exercise stress testing and documented coronary artery disease. Abnormal coronary vasoconstriction was induced by a hyperventilation test in 16 patients (group I) while the remaining 67 had a negative response (group II). No differences were observed between the 2 groups with regard to clinical, exercise and angiographic data. All group I patients and 16 patients in group II repeated hyperventilation and exercise tests after the administration of dihydropyridine-type calcium antagonists (7 patients nifedipine, 9 patients felodipine). After treatment 15 of 16 group I patients had a negative response to the hyperventilation test. The total exercise duration was significantly increased (278 +/- 183 vs 554 +/- 248 seconds; p less than 0.001) with higher values of rate pressure product at peak exercise (168 +/- 47 vs 235 +/- 67 mm Hg x beats/min/100; p less than 0.0025). In group II no significant differences were observed between pre- and posttreatment values for total exercise duration (244 +/- 210 vs 308 +/- 243 seconds) and rate pressure product at peak exercise (170 +/- 46 vs 188 +/- 56 mm Hg x beats/min/100). These data show that the hyperventilation test can be used to select a subset of patients with stable exertional angina and detectable abnormal coronary vasoconstriction who will improve their exercise tolerance with coronary vasodilator treatment.

Angina Pectoris↗
PubMed1990

Evidence for an intrinsic mechanism regulating heart rate variability in the transplanted and the intact heart during submaximal dynamic exercise?

STUDY OBJECTIVE: The aim was to assess the changes in sympatho-vagal balance which occur with exercise. DESIGN: The power spectrum of RR interval fluctuations (low frequency [LF] and high frequency components [HF]) was determined before, during, and after graded work load exercise on a cycle ergometer. The power spectrum of the respiratory signal, oxygen consumption, and respiratory volumes were also evaluated. In all subjects HF was considered to be an index of respiratory sinus arrhythmia. In normal subjects HF and LF were considered to be indices of relative vagal and sympathetic activity, respectively, whereas in heart transplant subjects HF was considered as a respiratory modulation of the intrinsic heart rate, and not dependent on autonomic tone. Heart rate variability was evaluated as RR interval variance. SUBJECTS: 15 normal subjects (six trained cyclists and nine healthy sedentary subjects) and six orthotopic heart transplant recipients took part in the study. MEASUREMENTS AND MAIN RESULTS: During the first part of exercise, heart rate increased, RR interval variance decreased, HF decreased, and the relative amount of LF increased both in sedentary and athletic subjects, suggesting a relative increase in sympathetic tone. However, when approaching peak exercise, while heart rate further increased and the variance slightly decreased, the relative proportion of LF decreased and HF proportionally increased. At peak exercise HF accounted for 99.9% of heart rate variability in athletic subjects and for 88.9% in sedentary subjects (p less than 0.001 v baseline and v LF in both groups). In heart transplant subjects both the variance and the HF increased from the beginning of exercise (p less than 0.05), and showed a direct correlation with ventilatory variables and an inverse correlation with heart rate (r = 0.794, p less than 0.001, multiple regression analysis). No measurable LF components could be obtained in these subjects. During recovery, while the heart rate decreased and the RR interval variance increased, there was a relative increase in LF and a relative decrease in HF in normal subjects (either sedentary or athletic). Similarly, in heart transplant subjects, there was a decrease in HF during recovery. Thus the increase in HF at peak exercise in normal subjects contrasts with all the other data which suggest a prevalence in sympathetic tone during the entire exercise and the early recovery period, but appears similar to the increase in HF observed in heart transplant subjects due to the effect of increased ventilation during exercise. CONCLUSIONS: These findings suggest that at peak exercise a non-autonomic mechanism, possibly intrinsic to the heart muscle, may determine heart rate fluctuations in synchrony with ventilation in the intact as well as in the denervated human heart.

Adolescent↗
PubMed1989

Significance of hyperventilation-induced ST segment depression in patients with coronary artery disease.

To investigate the significance of hyperventilation-induced ST segment depression, 329 consecutive patients with angina and documented coronary artery disease who underwent hyperventilation and exercise tests during pharmacologic washout were studied. The hyperventilation test induced ST segment depression in 79 patients. In 36 of these 79 patients, the electrocardiographic changes occurred early during overbreathing (Group I), whereas in 26 they occurred late during recovery (Group II). Seventeen patients developed ST segment depression both during over-breathing and during recovery (Group III). Group I patients had a higher frequency of history of angina during exercise, multivessel disease and lower tolerance to exercise as compared with patients in Group II. In Group I, the rate-pressure product at the time to onset of ST depression during overbreathing was similar to that during exercise (152 +/- 24 versus 148 +/- 42; p = NS), whereas in Group II the rate-pressure product at the time to onset of ST depression during recovery was comparable with that under control conditions (104 +/- 30 versus 98 +/- 27; p = NS) and far less than that required to produce ischemia during exercise (104 +/- 30 versus 201 +/- 56; p less than 0.0011). In nine Group III patients, the acute administration of propranolol prevented the early hyperventilation-induced ST segment depression, whereas nifedipine abolished the delayed hyperventilation-induced ST segment depression. These findings suggest that early hyperventilation-induced ST segment depression is due to increased oxygen demand in patients with poor coronary reserve and may be prevented by beta-adrenergic blockers, which are useful for lowering oxygen consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

A gene-cloning system for Kluyveromyces lactis and isolation of a chromosomal gene required for killer toxin production.

A transformation system derived from the circular plasmid pKD1 has been developed for Kluyveromyces lactis. The principle is essentially equivalent to that of the 2 microns/Saccharomyces cerevisiae transformation system. The main features of the system are presented. Using a pKD1-based DNA bank of K. lactis, the KEX1 gene involved in the killer system was isolated by complementation.

Cloning, Molecular↗
PubMed1988

Correlation between beta-endorphin plasma levels and anginal symptoms in patients with coronary artery disease.

To verify whether beta-endorphin plasma levels influence the presence of anginal symptoms, 74 consecutive male patients were studied. All patients had previously documented coronary artery disease and reproducible exercise-induced myocardial ischemia. Thirty-five patients (Group I) had a history of angina and reported anginal symptoms during exercise stress testing; 39 patients (Group II) were asymptomatic and had documented silent myocardial ischemia during exercise. Baseline beta-endorphin plasma levels were measured in blood samples taken before exercise stress testing and analyzed by beta-endorphin-I125-RIA Kit-NEN (a radioimmunoassay method). The mean baseline beta-endorphin plasma level was 22.5 +/- 19 pg/ml in patients with anginal symptoms compared with 43.7 +/- 28 pg/ml in asymptomatic patients (p less than 0.001). Baseline blood pressure and heart rate-systolic pressure (rate-pressure) product at baseline and at ischemia threshold (1 mm ST segment depression) were similar in the two groups. Group II patients had a longer exercise duration (p less than 0.01), more pronounced ST segment depression (p less than 0.001) and a higher peak rate-pressure product (p less than 0.01). The extent of coronary artery disease, ejection fraction and left ventricular end-diastolic pressure were similar in the two groups. These data suggest that higher baseline beta-endorphin plasma levels may play a role in the decreased sensitivity to pain in patients with silent myocardial ischemia. In addition, different beta-endorphin levels can be associated with a different sensitivity to pain.

Adult↗
PubMed1988

Dental pain threshold and angina pectoris in patients with coronary artery disease.

One hundred eight consecutive patients with proved coronary artery disease and reproducible exercise-induced myocardial ischemia were studied. During repeated exercise testing, 52 patients (Group I) had myocardial ischemia in the absence of pain (silent ischemia) whereas 56 patients (Group II) experienced anginal symptoms in the presence of electrocardiographic signs of ischemia. A pulpal test was carried out in all patients using an electrical dental stimulator commonly used in dentistry. Electrical current was delivered in increasing intensity from 10 to 500 mA, and the dental pain threshold and the reaction of the patients to maximal stimulation were determined. During the pulpal test, 71.2% of the patients in Group I did not experience pain, even at maximal stimulation (threshold 0), 11.5% were sensitive at threshold I (10 to 200 mA) and 17.3% felt pain at threshold II (210 to 500 mA). In Group II, 69.7% of the patients complained of dental pain at the low intensity test current (threshold I), 10.7% at threshold II and 19.6% at threshold 0. In Group I, 71.2% of patients did not have discomfort (reaction -), even at maximal stimulation, 21.1% had a mild reaction (reaction +) and 7.7% had an intense painful reaction (reaction ++). In Group II, 80.4% of patients were sensitive to the pulpar test (67.9% reported intense painful sensation at maximal stimulation, 12.5% had a mild reaction); 19.6% of patients had no reaction. The two groups of patients were similar with respect to age, sex and angiographic features.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1988

[Reproducibility of ergometric parameters at the ischemic threshold: study of 160 patients with effort coronary insufficiency].

To assess the reproducibility of ergometric parameters at the ischemic threshold, 160 patients, with coronary artery disease and exercise-induced S-T segment depression (102 with previous AMI), were evaluated by means of two control exercise tests performed, in pharmacological wash-out, on different days within 48 hours. The mean values of work load (WL), heart rate (HR) and double product (DP) did not show any statistical difference between the two exercise tests at 0.1 mV S-T depression (ischemic threshold), recorded by a computer assisted electrocardiograph system (Marquette CASE); on the contrary blood pressure (BP) slightly, but significantly (p less than 0.05) decreased at the second test (173.9 +/- 27.2 vs 179.8 +/- 25.8). The variability of the DP values in each subject at 0.1 mV S-T depression, expressed as numerical (delta) and percentage (delta %) differences, exhibited normal distributions. The delta DP showed a mean +/- 1 SD of -157.5 +/- 3271.5 beats x mmHg/min and the delta % DP a mean of +/- 1 SD of 1.46 +/- 16.4%. The values within a standard deviation from the mean (from +3114 to -3429 when numerical differences and from +17.8 to -14.9 when percentage differences) were used for defining the reproducibility of the ischemic threshold. No correlation was found between the delta % DP and the percentage differences in work load at the ischemic threshold. So, DP being more strictly related to MVO2, appears more apt in defining the ischemic threshold reproducibility. A good correlation (r = 0.821) was found between delta DP and delta % DP.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1987

Clinical significance of exercise-induced silent myocardial ischemia in patients with coronary artery disease.

Exercise-induced silent myocardial ischemia is a frequent feature in patients with coronary artery disease. The purpose of this study was to compare the clinical and angiographic characteristics of 269 patients who complained of chest pain during an exercise test (group I) with those of 204 who developed exercise-induced silent myocardial ischemia (group II). Group I patients more frequently had anginal symptoms of class III and IV of the Canadian Cardiovascular Society than did group II patients, who had milder symptoms (p less than 0.001). The only angiographic difference observed between the two groups was a slightly but significantly higher left ventricular end-diastolic pressure in group II patients (p less than 0.05), who also showed a longer exercise duration (p less than 0.01) with a higher heart rate-systolic pressure product (p less than 0.01) and more pronounced ST segment depression at peak exercise (p less than 0.001). Moreover, ventricular ectopic beats during exercise were more frequently observed in group II patients (p less than 0.05). Coronary bypass surgery was performed in 45% of patients of group I and in 24% of patients of group II (p less than 0.05). Survival curves of medically treated patients did not show any statistically significant difference between the two groups. Thus, although patients with a defective anginal warning system may have more pronounced signs of myocardial ischemia and a greater incidence of ventricular arrhythmias during exercise, their long-term prognosis is not different from that of patients who are stopped by angina from the activity that is inducing myocardial ischemia.

Coronary Angiography↗
PubMed1987

Variable threshold of exertional ischaemia in patients with positive exercise test at low workload.

In order to determine individual variability of ischaemic threshold on different days, 18 patients with exertional ischaemia at low workload were studied. All patients performed two exercise tests during different days in the morning and three on the same day at 9 am, 2 pm and 5 pm. The test performed in the morning on different days resulted in a significant difference in the mean values of rate pressure product at the ischaemic threshold as a consequence of individual variability observed in 10 patients. In 8 of these patients the differences were greater than 4000 mmHg beats min-1. Two patients showed respectively, 1 and 5 negative exercise tests despite the greater values of rate pressure product reached. Only 3 patients showed circadian variation of the ischaemic threshold; in these 3 patients variations of rate pressure product at the ischaemic threshold were also observed between different days. These data indicate that in patients with exertional ischaemia at low workload the rate pressure product at the ischaemic threshold shows considerable variability between tests performed on different days.

Angina Pectoris↗